JP2020161467A - Electrode, secondary battery, battery pack, and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode excellent in input / output characteristics and life characteristics, and a secondary battery, a battery pack, and a vehicle provided with the electrodes. According to embodiments, electrodes are provided. The electrode comprises a current collector and an active material-containing layer. The active material-containing layer is provided on the current collector and includes a first active material part and a second active material part. The first active material portion and the second active material portion are laminated with each other along the thickness direction and contain active material particles, respectively. The first active material section is located between the current collector and the second active material section. The length of the first active material portion is in the range of 0.7 T or more and 0.95 T or less with respect to the thickness T of the active material-containing layer. The length of the first active material portion is the length along the first direction, which is a direction parallel to the thickness direction of the active material-containing layer. The second active material portion further contains solid electrolyte particles. The ratio E1 / E2 of the content E1 (including 0) of the solid electrolyte particles per unit area of the first active material part and the content E2 of the solid electrolyte particles per unit area of the second active material part is 0. It is 0.01 or less. [Selection diagram] Fig. 1

Description

The present invention relates to electrodes, secondary batteries, battery packs, and vehicles.

A lithium ion secondary battery such as a non-aqueous electrolyte battery is a rechargeable battery that charges and discharges by moving lithium ions between a positive electrode and a negative electrode. The positive electrode and the negative electrode hold a non-aqueous electrolyte containing lithium ions. This promotes the movement of lithium ions between the positive electrode and the negative electrode.

In addition to being used as a power source for small electronic devices, non-aqueous electrolyte batteries are also expected to be used as medium- and large-sized power sources for in-vehicle applications and stationary applications. In particular, in applications as medium- and large-sized power supplies, it is required that the capacity is less likely to decrease when charged and discharged with a high current, that is, the rate characteristics are excellent.

Examples of the method for improving the rate characteristics of the secondary battery include thinning and reducing the density of the active material-containing layer of the electrode. According to such a method, the conductivity of lithium ions in the active material-containing layer is increased, so that the rate characteristics are improved. However, according to such a method, the energy density of the secondary battery is lowered. Therefore, it has been difficult to realize a secondary battery having excellent both rate characteristics and energy density.

JP-A-2015-216101 JP-A-2018-049705

According to the present embodiment, an electrode having excellent rate characteristics and energy density, and a secondary battery, a battery pack, and a vehicle provided with the electrode are provided.

According to one embodiment, electrodes are provided. The electrode includes a current collector and an active material-containing layer. The active material-containing layer is provided on the current collector and includes a first active material part and a second active material part. The first active material part and the second active material part are laminated with each other along the thickness direction, and each contains active material particles. The first active material section is located between the current collector and the second active material section. The length of the first active material portion is in the range of 0.7 T or more and 0.95 T or less with respect to the thickness T of the active material-containing layer. The length of the first active material portion is a length along the first direction, which is a direction parallel to the thickness direction of the active material-containing layer. The second active material portion further contains solid electrolyte particles. The ratio E1 / E2 of the content E1 (including 0) of the solid electrolyte particles per unit area of the first active material part and the content E2 of the solid electrolyte particles per unit area of the second active material part is 0. It is 0.01 or less.

According to other embodiments, a secondary battery is provided. This secondary battery includes the electrodes according to the embodiment.

According to other embodiments, battery packs are provided. This battery pack comprises the secondary battery according to the embodiment.

According to other embodiments, a vehicle is provided. This vehicle is equipped with the battery pack according to the embodiment.

FIG. 5 is a cross-sectional view schematically showing an example of an electrode according to an embodiment. FIG. 5 is a cross-sectional view schematically showing an example of a secondary battery according to an embodiment. FIG. 2 is an enlarged cross-sectional view of part A of the secondary battery shown in FIG. Partial cutaway perspective view schematically showing another example of the secondary battery which concerns on embodiment. FIG. 4 is an enlarged cross-sectional view of a portion B of the secondary battery shown in FIG. The perspective view which shows typically an example of the assembled battery which concerns on embodiment. An exploded perspective view schematically showing an example of a battery pack according to an embodiment. The block diagram which shows an example of the electric circuit of the battery pack shown in FIG. FIG. 5 is a cross-sectional view schematically showing an example of a vehicle according to an embodiment. The figure which showed the other example of the vehicle which concerns on embodiment.

[First Embodiment]
According to embodiments, electrodes are provided. The electrode includes a current collector and an active material-containing layer. The active material-containing layer is provided on the current collector and includes a first active material part and a second active material part. The first active material part and the second active material part are laminated with each other along the thickness direction, and each contains active material particles. The first active material section is located between the current collector and the second active material section. The length of the first active material portion is in the range of 0.7 T or more and 0.95 T or less with respect to the thickness T of the active material-containing layer. The length of the first active material portion is a length along the first direction, which is a direction parallel to the thickness direction of the active material-containing layer. The second active material portion further contains solid electrolyte particles. The ratio E1 / E2 of the content E1 (including 0) of the solid electrolyte particles per unit area of the first active material part and the content E2 of the solid electrolyte particles per unit area of the second active material part is 0. It is 0.01 or less.

The electrode according to the embodiment includes an active material-containing layer including a first active material portion located on the current collector side and a second active material portion located on the surface side. The active material-containing layer may have a two-layer structure including a first active material part and a second active material part. The first active material part contains active material particles and optionally solid electrolyte particles. The second active material part includes active material particles and solid electrolyte particles. The amount of the solid electrolyte particles contained in the second active material portion is larger than the amount of the solid electrolyte particles contained in the first active material portion.

According to the electrode according to the embodiment, a secondary battery excellent in both rate characteristics and energy density can be realized. That is, when discharging is performed by separating the positive electrode and the negative electrode with a separator, lithium ions move from the negative electrode side to the positive electrode side, and from the interface between the separator and the positive electrode active material-containing layer to the positive electrode active material-containing layer. It is stored in the positive electrode active material particles toward the inside. When charging is performed, lithium ions move from the positive electrode side to the negative electrode side, and enter the negative electrode active material particles from the interface between the separator and the negative electrode active material-containing layer toward the inside of the negative electrode active material-containing layer. It is stored. However, when charging / discharging is performed with a large current, the concentration of lithium ions is locally increased at the interface between the separator and the active material-containing layer as compared with the case where charging / discharging is performed with a low current. Then, the occlusion or release reaction of lithium ions into the active material particles is concentrated at this interface. As a result, the movement of lithium ions from the surface side of the active material-containing layer to the inside is hindered, the charging or discharging reaction is not sufficiently performed on the current collector side of the active material-containing layer, and the charge / discharge capacity is reduced.

As a method for improving such a problem, there is a method of mixing the solid electrolyte particles with the active material-containing layer. Since the solid electrolyte particles have excellent lithium ion conductivity, when the solid electrolyte particles are mixed in the active material-containing layer, the lithium ion conductivity in the active material-containing layer becomes higher than that in the case where the solid electrolyte particles are not contained. Increase. On the other hand, when the proportion of the solid electrolyte particles in the active material-containing layer increases, the proportion of the active material particles decreases, so that the energy density of the electrode can decrease.

In the electrode according to the embodiment, the solid electrolyte particles are arranged on the surface side of the active material-containing layer in which lithium ions are locally concentrated. As a result, the intensive charging and discharging reactions between the lithium ions and the active material particles are suppressed on the surface side, and the movement of the lithium ions from the surface side to the inside of the active material-containing layer is promoted. Therefore, in the active material-containing layer located on the current collector side, the proportion of solid electrolyte particles is significantly lower than that in the active material-containing layer located on the surface side, or even if the solid electrolyte particles are not contained, lithium ions are formed. The storage or release reaction of the above can be sufficiently carried out. Therefore, the electrode according to the embodiment can reduce the amount of solid electrolyte particles contained in the active material-containing layer located on the current collector side. From the above, the electrode according to the embodiment can have both excellent rate characteristics and high energy density.

FIG. 1 is a cross-sectional view schematically showing an example of an electrode according to an embodiment. FIG. 1 is a cross-sectional view of the electrode 500 cut along an XZ plane perpendicular to the X direction which is the short side direction or the long side direction and the Z direction which is the thickness direction. The electrode 500 shown in FIG. 1 includes a current collector 50 and an active material-containing layer 51 provided on the current collector 50. The current collector 50 includes a portion that does not support the active material-containing layer 51, that is, a tab 50a. The active material-containing layer 51 includes a first active material portion 511 and a second active material portion 512 that are laminated with each other along the Z direction. The first active material section 511 is located between the current collector 50 and the second active material section 512 in the Z direction. The first active material section 511 can be rephrased as the current collector side portion of the active material-containing layer 51. Further, the second active material portion 512 can be rephrased as a surface side portion of the active material-containing layer 51.

The length L1 of the first active material section 511 in the Z direction is the length from the main surface of the current collector 50 to the boundary BO with the second active material section 512. The length L1 is in the range of 0.7T or more and 0.95T or less with respect to the thickness T of the active material-containing layer. The length L1 is, for example, 15 μm or more and 80 μm or less.

The length L2 of the second active material portion 512 in the Z direction is the length from the boundary BO, which is the surface of the first active material portion 511, to the main surface of the active material-containing layer 51. In other words, the length L2 is a value (TL1) obtained by subtracting the length L1 of the first active material portion from the thickness T of the active material-containing layer. The length L2 is, for example, 3 μm or more and 20 μm or less.

The thickness T of the active material-containing layer, the lengths L1 and L2 of the first and second active material parts, the content E1 of the solid electrolyte particles per unit area of the first active material part, and the second active material part. The content E2 of the solid electrolyte particles per unit area can be confirmed by the following method.

First, the electrode is taken out from the battery. When the active material particles of the electrode according to the embodiment are made of titanium dioxide, a titanium composite oxide, a niobium titanium composite oxide, and a sodium-containing titanium composite oxide, and when this electrode is used as a positive electrode, a battery is used. It is preferable to take it out after charging it. Further, when the electrode according to the embodiment is used as the negative electrode, it is preferable to take out the battery after discharging it.

The active material particles of the electrode according to the embodiment are lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, lithium manganese nickel composite oxide, lithium manganese cobalt composite oxide, and the like. In the case of composed of iron lithium phosphate and lithium nickel cobalt manganese composite oxide, when this electrode is used as a positive electrode, it is preferable to take out the battery after discharging it. Further, when the electrode according to the embodiment is used as the negative electrode, it is preferable to take out the battery after charging it.

The removed electrode is washed with an organic solvent such as ethyl methyl carbonate, and then the current collector is removed to obtain a test piece. In this test piece, the main surface of the active material-containing layer exposed by removing the current collector is set as the deepest surface. The main surface of the active material-containing layer on the opposite side of the deepest surface is the outermost surface. The length from the deepest surface to the outermost surface is measured using a scanning electron microscope (SEM), and the thickness T of the active material-containing layer is taken.

Next, the cross section of the active material-containing layer in the thickness direction is subjected to elemental analysis using Energy Dispersive X-ray spectroscopy (EDX). This confirms the elements contained in the active material-containing layer.

Next, the deepest surface is analyzed using X-ray Photoelectron Spectroscopy (XPS). In the XPS analysis, the elements confirmed by the above EDX analysis excluding lithium and oxygen are selected. The measurement area for XPS analysis is, for example, 200 μmφ. Further, since the surface is analyzed in the XPS analysis, the analysis depth of the measurement region is 5 nm or less. By this XPS analysis, the atomic concentration of each element on the deepest surface of the active material-containing layer can be measured. Then, by calculating the atomic concentration of the element peculiar to the solid electrolyte particles in the atomic concentration of the observed elements excluding lithium and oxygen, it can be regarded as the content per unit area of the solid electrolyte particles in the measurement region.

The element peculiar to the solid electrolyte particles is, for example, at least one element selected from the group consisting of La, Zr, Al and Ca. That is, the sum of the atomic concentrations of La, Zr, Al, and Ca in the atomic concentrations of the observed elements excluding lithium and oxygen in the measurement region on the deepest surface is calculated. When calculating the atomic concentration, the total atomic concentration of the solid electrolyte particles is calculated at five measurement points on the deepest surface, and the average value thereof is obtained. This average value is taken as the content of the solid electrolyte particles on the deepest surface. The five measurement points are provided, for example, at the center position in the short side direction of the deepest surface and at equal intervals along the long side direction.

Next, a region having a length of 1/10 of the thickness T of the active material-containing layer is removed from the deepest surface along the thickness direction of the active material-containing layer, and the thickness T of the active material-containing layer is removed from the deepest surface. The surface of the active material-containing layer, which is located at a depth of 1/10 of the above and is parallel to the deepest surface, is exposed. Hereinafter, this surface is referred to as the first surface. For cutting the active material-containing layer, for example, a surface cutting device such as SAICAS (registered trademark, Surface And Interfacial Cutting Analysis System) is used. The depth of the region to be removed may be a thickness of 3 μm. The first surface is subjected to XPS analysis in the same manner as the deepest surface to obtain the content of the solid electrolyte particles on the first surface.

A series of these operations is performed along the thickness direction of the active material-containing layer for each length of 1/10 of the thickness T of the active material-containing layer until the X-plane is reached. The X-th surface is an active material-containing layer parallel to the deepest surface located at a depth of 1/10 TX of the thickness T of the active material-containing layer from the deepest surface of the active material-containing layer obtained in the Xth operation. This is the surface where the average value of the content of the solid electrolyte particles exceeds the threshold value for the first time. The threshold value is, for example, 100 times the average value of the contents of the solid electrolyte particles on the first to X-1 planes. The threshold is, for example, 10 atm%. The X-1th plane is a plane obtained by the operation one time before the Xth plane. The average value of the contents of the solid electrolyte particles on the first surface to the X-1 surface is defined as the content E1 of the solid electrolyte particles per unit area of the first active material part.

Next, the position of the plane located between the X-th plane and the X-1 plane and parallel to the deepest plane is confirmed. That is, the surface located between the X-th surface and the X-1 surface is located (1/10 TX-1 / 20T) μm from the deepest surface. This surface is defined as the boundary surface between the first active material section and the second active material section.

Next, the above series of operations is performed from the Xth plane to the outermost surface. The average value of the contents of the solid electrolyte particles on the X-plane to the outermost surface is defined as the content E2 of the solid electrolyte particles per unit area of the second active material part.

Further, by the above method, the length L1 of the first active material part and the length L2 of the second active material part can be calculated. That is, the length of the first active material part is (1/10 TX-1 / 20T) μm, and the length of the second active material part is (T- (1/10 TX-1 / 20T)) μm. .. Here, T is the thickness of the active material-containing layer.

The content E1 of the solid electrolyte particles per unit area of the first active material portion is preferably lower than 0.1 atm%, more preferably 0.07 atm% or less. The content E1 of the solid electrolyte particles per unit area of the first active material portion is more preferably 0 atm%. When the content E1 is low, the proportion of active material particles can be increased to further increase the energy density of the secondary battery.

The content E2 of the solid electrolyte particles per unit area of the second active material portion is preferably 10 atm% or more, and more preferably 10.5 atm% or more. When the content E2 is high, the movement of lithium ions on the surface side of the active material-containing layer is promoted, so that the rate characteristics are enhanced. On the other hand, if the content E2 is excessively high, the proportion of active material particles and the energy density of the secondary battery may decrease. Therefore, the content E2 is preferably 18 atm% or less, and more preferably 15 atm% or less.

In the second active material part, it is preferable that the solid electrolyte particles are uniformly mixed in the active material-containing layer. In such a state, the conductivity of lithium ions is further enhanced. The term that the solid electrolyte particles are uniformly mixed in the second active material portion means that the average value of the solid electrolyte contents of each of the X-plane to the outermost surface is subtracted from the content E2 of the second active material portion. However, it means that they are within the range of -4% or more and 4% or less, respectively.

Further, even when the first active material portion contains solid electrolyte particles, it is preferable that the solid electrolyte particles are uniformly mixed in the active material-containing layer. When the solid electrolyte particles are uniformly mixed in the first active material portion, the content of each of the solid electrolyte particles on the deepest surface to the X-1 surface is defined as the content of the solid electrolyte particles in the second active material portion. It means that the values subtracted from E1 are within the range of -4% or more and 4% or less, respectively.

The content E3 of the active material particles per unit area of the first active material part is preferably 50 atm% or more, and more preferably 80 atm% or more. When the content E3 is high, the proportion of active material particles can be increased, and the energy density of the secondary battery can be further increased. According to one example, the upper limit of the content E3 is 90 atm% or less.

The content E4 of the active material particles per unit area of the second active material part is preferably 30 atm% or more, and more preferably 60 atm% or more. If the content E4 is high, the energy density of the secondary battery may decrease. On the other hand, if the content E4 is excessively high, the rate characteristics may deteriorate. Therefore, the content E4 is preferably 85 atm% or less, and more preferably 80 atm% or less.

The contents E3 and E4 of the active material particles per unit area of the first active material part and the second active material part shall be calculated by the same method as the above-mentioned contents E1 and E2 of the solid electrolyte particles per unit area. Can be done.

When the electrode is a positive electrode, the element peculiar to the positive electrode active material particles is at least one selected from the group consisting of Ni, Mn, Co, and Fe. Therefore, the sum of the atomic concentrations of these elements in the atomic concentrations of the observed elements except lithium and oxygen is regarded as the content of the active material particles.

When the electrode is a negative electrode, the element peculiar to the negative electrode active material particles is at least one selected from the group consisting of Ti, Nb, Si, and C. Therefore, the sum of the atomic concentrations of these elements in the atomic concentrations of the observed elements except lithium and oxygen is regarded as the content of the active material particles.

As the solid electrolyte particles, it is preferable to use an inorganic solid electrolyte. Examples of the inorganic solid electrolyte include an oxide-based solid electrolyte and a sulfide-based solid electrolyte.

The solid electrolyte particles are at least one selected from the group consisting of perovskite-type lithium lanthanum titanium-containing oxides, garnet-type lithium lanthanum zirconium-containing oxides, NASICON-type lithium aluminum titanium-containing oxides, and lithium calcium zirconium-containing oxides. Is preferably used.

As the oxide-based solid electrolyte, it is preferable to use a lithium phosphoric acid solid electrolyte having a NASICON type structure and represented by the general formula LiM ₂ (PO ₄ ) ₃ . M in the above general formula is at least selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). It is preferably one or more kinds of elements. The element M is more preferably at least one kind of element selected from the group consisting of Zr, Ca, Al and Ti.

Specific examples of the lithium phosphate solid electrolyte having a NASICON type structure include LATP (Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ ) and Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ , Li _{1 + x} Al _x Zr _2-x (PO ₄ ) ₃ . In the above formula, x is in the range of 0 <x ≦ 5, and preferably in the range of 0.1 ≦ x ≦ 0.5. It is preferable to use LATP as the solid electrolyte.

Further, as the oxide-based solid electrolyte, amorphous LIPON (Li _2.9 PO _3.3 N _0.46 ) or LLZ having a garnet-type structure (Li ₇ La ₃ Zr ₂ O ₁₂ ) may be used. The solid electrolyte may be used alone or in combination of two or more.

The active material-containing layer can be formed on one side or both sides of the current collector. The active material-containing layer can contain an active material and optionally a conductive agent and a binder. The active material-containing layer may contain the active material alone, or may contain two or more kinds of active materials. The electrode according to the embodiment may be used as a positive electrode or a negative electrode.

Details of the case where the electrode according to the embodiment is used as the negative electrode will be described.

Examples of the negative electrode active material include lithium titanate having a rams delite structure (for example, Li _{2 + y} Ti ₃ O ₇ , 0 ≦ y ≦ 3) and lithium titanate having a spinel structure (for example, Li _{4 + x} Ti ₅ O _12). , 0 ≦ x ≦ 3), monoclinic titanium dioxide (TiO ₂ ), anatase titanium dioxide, rutile titanium dioxide, hollandite titanium composite oxide, orthorhombic titanium composite oxide, and monoclinic It is preferable to use a crystalline niobium titanium composite oxide.

Examples of the above-mentioned orthorhombic titanium-containing composite oxide include a compound represented by Li _{2 + a} M (I) _2-b Ti _6-c M (II) _d O _{14 + σ} . Here, M (I) is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb and K. M (II) is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. Each subscript in the composition formula is 0 ≦ a ≦ 6, 0 ≦ b <2, 0 ≦ c <6, 0 ≦ d <6, −0.5 ≦ σ ≦ 0.5. Specific examples of the orthorhombic titanium-containing composite oxide include Li _{2 + a} Na ₂ Ti ₆ O ₁₄ (0 ≦ a ≦ 6).

Examples of the monoclinic niobium-titanium composite oxide include compounds represented by Li _x Ti _1-y M1 _y Nb _2-z M2 _z O _{7 + δ} . Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. The respective subscripts in the composition formula are 0 ≦ x ≦ 5, 0 ≦ y <1, 0 ≦ z ≦ 2, and −0.3 ≦ δ ≦ 0.3. Specific examples of the monoclinic niobium-titanium composite oxide include Li _x Nb ₂ TiO ₇ (0 ≦ x ≦ 5).

Another example of the monoclinic niobium-titanium composite oxide is a compound represented by Li _x Ti _1-y M3 _{y + z} Nb _2-z O _7-δ . Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. The respective subscripts in the composition formula are 0 ≦ x <5, 0 ≦ y <1, 0 ≦ z ≦ 2, and −0.3 ≦ δ ≦ 0.3.

The conductive agent is blended in order to improve the current collecting performance and suppress the contact resistance between the active material and the current collector. Examples of conductive agents include carbon blacks such as Vapor Grown Carbon Fiber (VGCF), acetylene black and carbonaceous materials such as graphite. One of these may be used as a conductive agent, or two or more of them may be used as a conductive agent in combination. Alternatively, instead of using a conductive agent, a carbon coat or an electron conductive inorganic material coat may be applied to the surface of the active material particles.

The binder is blended to fill the gaps between the dispersed active materials and to bind the active material to the negative electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene butagen rubber, polyacrylic acid compounds, imide compounds, and carboxymethyl cellulose. cellulose; CMC), and salts of CMC. One of these may be used as a binder, or a combination of two or more may be used as a binder.

The composition of the active material (negative electrode active material), the conductive agent and the binder in the active material-containing layer is 68% by mass or more and 96% by mass or less, 2% by mass or more and 30% by mass or less, and 2% by mass or more and 30% by mass, respectively. The ratio is preferably% or less. By setting the amount of the conductive agent to 2% by mass or more, the current collecting performance of the active material-containing layer can be improved. Further, by setting the amount of the binder to 2% by mass or more, the binding property between the active material-containing layer and the current collector becomes sufficient, and excellent cycle performance can be expected. On the other hand, it is preferable that the conductive agent and the binder are each 30% by mass or less in order to increase the capacity.

When a carbon material is used as the active material, the density of the negative electrode active material-containing layer is preferably 1.0 g / cm ³ or more and 1.5 g / cm ³ or less. When a titanium composite oxide is used as the active material, it is preferably 2.0 g / cm ³ or more and 2.8 g / cm ³ or less.
A negative electrode having a density of the negative electrode active material-containing layer within this range is excellent in energy density and electrolyte retention. When a carbon material is used as the active material, the density of the negative electrode active material-containing layer is more preferably 1.1 g / cm ³ or more and 1.3 g / cm ³ or less. When a titanium composite oxide is used as the active material, it is more preferably 2.1 g / cm ³ or more and 2.5 g / cm ³ or less.

As the current collector, a material that is electrochemically stable at the potential at which lithium (Li) is inserted into and desorbed from the active material is used. The current collector is preferably made of copper, nickel, stainless steel or aluminum, or an aluminum alloy containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. The thickness of the current collector is preferably 5 μm or more and 20 μm or less. A current collector having such a thickness can balance the strength and weight reduction of the electrodes.

Further, the current collector may include a portion on which the negative electrode active material-containing layer is not formed on the surface thereof. This portion can serve as a negative electrode current collector tab.

The electrode can be produced, for example, by the following method. First, a slurry is prepared by suspending an active material, a conductive agent and a binder in a solvent. This slurry is applied to one or both sides of the current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. Then, the laminate is pressed. In this way, the electrode is manufactured.

Alternatively, the electrode may be manufactured by the following method. First, the active material, the conductive agent and the binder are mixed to obtain a mixture. The mixture is then molded into pellets. The electrodes can then be obtained by arranging these pellets on the current collector.

Next, details of the case where the electrode according to the embodiment is used as the positive electrode will be described.
As the positive electrode active material, for example, an oxide or a sulfide can be used. The positive electrode may contain one kind of compound alone or may contain two or more kinds of compounds in combination as the positive electrode active material. Examples of oxides and sulfides include compounds capable of inserting and desorbing Li or Li ions.

Such compounds include, for example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (eg Li _x Mn ₂ O ₄ or Li _x MnO ₂ ; 0 <x ≦ 1). , Lithium-nickel composite oxide (eg Li _x NiO ₂ ; 0 <x ≦ 1), Lithium cobalt composite oxide (eg Li _x CoO ₂ ; 0 <x ≦ 1), Lithium nickel-cobalt composite oxide (eg Li _x Ni) _1-y Co _y O ₂ ; 0 <x ≦ 1, 0 <y <1), lithium manganese cobalt composite oxide (for example, Li _x Mn _y Co _1-y O ₂ ; 0 <x ≦ 1, 0 <y < 1), Lithium manganese nickel composite oxide having a spinel structure (for example, Li _x Mn _2-y N _y O ₄ ; 0 <x ≦ 1, 0 <y <2), Lithium phosphorus oxide having an olivine structure (for example, Li) _x FePO ₄ ; 0 <x≤1, Li _x Fe _1-y Mn _y PO ₄ ; 0 <x≤1, 0 <y <1, Li _x CoPO ₄ ; 0 <x≤1), iron sulfate (Fe ₂₎ (SO _{4) 3),} vanadium oxide (e.g. V ₂ O _5), and a lithium-nickel-cobalt-manganese composite oxide _{(Li x Ni 1-yz Co} y Mn z O 2; 0 <x ≦ 1,0 <y <1, 0 <z <1, y + z <1) are included.

Among the above, examples of compounds that are more preferable as the positive electrode active material include a lithium manganese composite oxide having a spinel structure (for example, Li _x Mn ₂ O ₄ ; 0 <x ≦ 1) and a lithium nickel composite oxide (for example, Li _{x). NiO 2; 0 <x ≦ 1} ), lithium-cobalt composite oxide (e.g., _{Li x CoO 2; 0 <x} ≦ 1), lithium-nickel-cobalt composite oxide (e.g., _{Li x Ni 1-y Co y} O 2; 0 < x ≦ 1, 0 <y <1), lithium manganese nickel composite oxide having a spinel structure (for example, Li _x Mn _2-y N _y O ₄ ; 0 <x ≦ 1, 0 <y <2), lithium manganese cobalt Composite oxides (eg Li _x Mn _y Co _1-y O ₂ ; 0 <x ≦ 1, 0 <y <1), iron lithium phosphate (eg Li _x FePO ₄ ; 0 <x ≦ 1), and lithium included; (0 <x ≦ 1,0 < y <1,0 <z <1, y + z <1 Li x Ni 1-yz Co y Mn z O 2) nickel-cobalt-manganese composite oxide. When these compounds are used as the positive electrode active material, the positive electrode potential can be increased.

When a room temperature molten salt is used as the electrolyte of the battery, lithium iron phosphate, Li _x VPO ₄ F (0 ≦ x ≦ 1), lithium manganese composite oxide, lithium nickel composite oxide, lithium nickel cobalt composite oxide, or these It is preferable to use a positive electrode active material containing a mixture of. Since these compounds have low reactivity with the molten salt at room temperature, the cycle life can be improved. Details of the room temperature molten salt will be described later.

The primary particle size of the positive electrode active material is preferably 100 nm or more and 1 μm or less. A positive electrode active material having a primary particle size of 100 nm or more is easy to handle in industrial production. A positive electrode active material having a primary particle size of 1 μm or less can smoothly promote the diffusion of lithium ions in a solid.

The specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more and 10 m ² / g or less. A positive electrode active material having a specific surface area of 0.1 m ² / g or more can sufficiently secure an occlusion / release site for Li ions. A positive electrode active material having a specific surface area of 10 m ² / g or less is easy to handle in industrial production and can ensure good charge / discharge cycle performance.

The binder is blended to fill the gaps between the dispersed positive electrode active materials and to bind the positive electrode active material and the positive electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, polyacrylic acid compounds, imide compounds, and carboxy methyl cellulose (CMC). , And CMC salts. One of these may be used as a binder, or a combination of two or more may be used as a binder.

The conductive agent is blended in order to improve the current collecting performance and suppress the contact resistance between the positive electrode active material and the positive electrode current collector. Examples of conductive agents include carbon blacks such as Vapor Grown Carbon Fiber (VGCF), acetylene black and carbonaceous materials such as graphite. One of these may be used as a conductive agent, or two or more of them may be used as a conductive agent in combination. Moreover, the conductive agent can be omitted.

In the positive electrode active material-containing layer, the positive electrode active material and the binder are preferably blended in a proportion of 80% by mass or more and 98% by mass or less and 2% by mass or more and 20% by mass or less, respectively.

Sufficient electrode strength can be obtained by setting the amount of the binder to 2% by mass or more. Also, the binder can function as an insulator. Therefore, when the amount of the binder is 20% by mass or less, the amount of the insulator contained in the electrode is reduced, so that the internal resistance can be reduced.

When a conductive agent is added, the positive electrode active material, the binder and the conductive agent are 77% by mass or more and 95% by mass or less, 2% by mass or more and 20% by mass or less, and 3% by mass or more and 15% by mass or less, respectively. It is preferable to mix in a ratio.

By setting the amount of the conductive agent to 3% by mass or more, the above-mentioned effect can be exhibited. Further, by setting the amount of the conductive agent to 15% by mass or less, the proportion of the conductive agent in contact with the electrolyte can be reduced. When this ratio is low, decomposition of the electrolyte can be reduced under high temperature storage.

The positive electrode current collector is preferably an aluminum foil or an aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu and Si.

The thickness of the aluminum foil or the aluminum alloy foil is preferably 5 μm or more and 20 μm or less, and more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. The content of transition metals such as iron, copper, nickel, and chromium contained in the aluminum foil or the aluminum alloy foil is preferably 1% by mass or less.

The density of the positive electrode active material-containing layer is preferably 2.6 g / cm ³ or more and 3.4 g / cm ³ or less. A positive electrode having a density of a positive electrode active material-containing layer within this range is excellent in energy density and electrolyte retention. The density of the positive electrode active material-containing layer is more preferably 2.8 g / cm ³ or more and 3.2 g / cm ³ or less.

Further, the positive electrode current collector may include a portion on the surface of which the positive electrode active material-containing layer is not formed. This portion can serve as a positive electrode current collector tab.

Next, a method for manufacturing the electrode according to the embodiment will be described.
First, a first slurry for forming the first active material portion is prepared. The first slurry is obtained by mixing the active material particles, optionally contained solid electrolyte particles, a conductive agent and a binder, and a solvent. The proportions of the active material particles, the solid electrolyte particles, the conductive agent, and the binder in the components excluding the solvent contained in the first slurry are 70% by mass or more and 90% by mass or less and 0% by mass or more and 0.1, respectively. It is preferably 1% by mass or less, 1% by mass or more and 15% by mass or less, and 1% by mass or more and 15% by mass or less.

Next, a second slurry for forming the second active material portion is prepared. The second slurry is obtained by mixing active material particles, solid electrolyte particles, a conductive agent and a binder optionally contained, and a solvent. The types of the active material particles, the solid electrolyte particles, the conductive agent and the binder contained in the second slurry may be the same as those contained in the first slurry, or may be different. The proportions of the active material particles, the solid electrolyte particles, the conductive agent, and the binder in the components excluding the solvent contained in the second slurry are 70% by mass or more and 90% by mass or less and 5% by mass or more and 20% by mass, respectively. Hereinafter, it is preferably 1% by mass or more and 10% by mass or less, and 1% by mass or more and 10% by mass or less.

Next, these are simultaneously coated on the current collector so that the second slurry overlaps the first slurry. For simultaneous coating of the first and second slurries, for example, a coating machine in which the first discharge port and the second discharge port are located vertically is used. The first discharge port communicates with the first accommodating portion for accommodating the first slurry. The second discharge port dries the first and second slurries coated on the current collector communicating with the second accommodating portion for accommodating the second slurry to obtain a laminated body. The laminate is pressed and cut to a predetermined size. By vacuum drying the cut laminate, an electrode containing the first and second active material portions is obtained.

The electrode according to the first embodiment described above has a second active material portion containing solid electrolyte particles and a first portion having a smaller content of solid electrolyte particles or not containing solid electrolyte particles as compared with the second active material portion. Includes active material section. Therefore, when this electrode is used, a secondary battery having excellent rate characteristics and energy density can be realized.

[Second Embodiment]
According to the second embodiment, a secondary battery including a negative electrode, a positive electrode, and an electrolyte is provided. At least one of the negative electrode and the positive electrode is the electrode according to the first embodiment.

The secondary battery according to the second embodiment may further include a separator arranged between the positive electrode and the negative electrode. The negative electrode, the positive electrode and the separator can form an electrode group. The electrolyte can be retained in the electrode group.

In addition, the secondary battery according to the second embodiment can further include an electrode group and an exterior member accommodating an electrolyte.

Further, the secondary battery according to the second embodiment can further include a negative electrode terminal electrically connected to the negative electrode and a positive electrode terminal electrically connected to the positive electrode.

The secondary battery according to the second embodiment can be, for example, a lithium secondary battery. Further, the secondary battery includes a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte.

Hereinafter, the electrolyte, the separator, the exterior member, the negative electrode terminal, and the positive electrode terminal will be described in detail.

1) Electrolyte As the electrolyte, for example, a liquid non-aqueous electrolyte or a gel-like non-aqueous electrolyte can be used. The liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt as a solute in an organic solvent. The concentration of the electrolyte salt is preferably 0.5 mol / L or more and 2.5 mol / L or less.

Examples of electrolyte salts include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoromethane. Includes lithium salts such as lithium sulfonate (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimide lithium (LiN (CF ₃ SO ₂ ) ₂ ), and mixtures thereof. The electrolyte salt is preferably one that is difficult to oxidize even at a high potential, and LiPF ₆ is most preferable.

Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate (VC); diethyl carbonate (DEC), dimethyl carbonate. (Dimethyl carbonate; DMC), chain carbonates such as methyl ethyl carbonate (MEC); tetrahydrofuran (tetrahydrofuran; THF), 2-methyl tetrahydrofuran (2MeTHF), dioxolane (DOX). Cyclic ethers such as; chain ethers such as dimethoxy ethane (DME), diethoxy ethane (DEE); γ-butyrolactone (GBL), acetonitrile (acetonitrile; AN), and sulfolanes. (Sulfolane; SL) is included. These organic solvents can be used alone or as a mixed solvent.

The gel-like non-aqueous electrolyte is prepared by combining a liquid non-aqueous electrolyte and a polymer material. Examples of polymeric materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

Alternatively, as the non-aqueous electrolyte, in addition to the liquid non-aqueous electrolyte and the gel-like non-aqueous electrolyte, a room temperature molten salt (ionic melt) containing lithium ions, a polymer solid electrolyte, an inorganic solid electrolyte and the like are used. May be good.

The room temperature molten salt (ionic melt) refers to a compound that can exist as a liquid at room temperature (15 ° C. or higher and 25 ° C. or lower) among organic salts composed of a combination of an organic cation and an anion. The room temperature molten salt includes a room temperature molten salt that exists as a liquid by itself, a room temperature molten salt that becomes a liquid when mixed with an electrolyte salt, a room temperature molten salt that becomes a liquid when dissolved in an organic solvent, or a mixture thereof. Is done. Generally, the melting point of a room temperature molten salt used in a secondary battery is 25 ° C. or lower. In addition, the organic cation generally has a quaternary ammonium skeleton.

Polymer solid electrolyte is prepared by dissolving an electrolyte salt in a polymer material and solidifying it.

The inorganic solid electrolyte is a solid substance having Li ion conductivity.

2) Separator The separator is formed of, for example, a porous film containing polyethylene (PE), polypropylene (PP), cellulose, or polyvinylidene fluoride (PVdF), or a non-woven fabric made of synthetic resin. From the viewpoint of safety, it is preferable to use a porous film made of polyethylene or polypropylene. This is because these porous films can be melted at a constant temperature to cut off an electric current.

3) Exterior member As the exterior member, for example, a container made of a laminated film or a metal container can be used.

The thickness of the laminated film is, for example, 0.5 mm or less, preferably 0.2 mm or less.

As the laminated film, a multilayer film including a plurality of resin layers and a metal layer interposed between the resin layers is used. The resin layer contains, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). The metal layer is preferably made of an aluminum foil or an aluminum alloy foil for weight reduction. The laminated film can be molded into the shape of an exterior member by sealing by heat fusion.

The wall thickness of the metal container is, for example, 1 mm or less, more preferably 0.5 mm or less, still more preferably 0.2 mm or less.

The metal container is made of, for example, aluminum or an aluminum alloy. The aluminum alloy preferably contains elements such as magnesium, zinc, and silicon. When the aluminum alloy contains a transition metal such as iron, copper, nickel, and chromium, the content thereof is preferably 100 mass ppm or less.

The shape of the exterior member is not particularly limited. The shape of the exterior member may be, for example, a flat type (thin type), a square type, a cylindrical type, a coin type, a button type, or the like. The exterior member can be appropriately selected according to the battery size and the application of the battery.

4) Negative electrode terminal The negative electrode terminal can be formed from a material that is electrochemically stable and has conductivity at the Li storage / release potential of the above-mentioned negative electrode active material. Specifically, the material of the negative electrode terminal contains at least one element selected from the group consisting of copper, nickel, stainless steel or aluminum, or Mg, Ti, Zn, Mn, Fe, Cu, and Si. Aluminum alloy can be mentioned. As the material of the negative electrode terminal, it is preferable to use aluminum or an aluminum alloy. The negative electrode terminal is preferably made of the same material as the negative electrode current collector in order to reduce the contact resistance with the negative electrode current collector.

5) Positive electrode terminal The positive electrode terminal shall be formed of a material that is electrically stable and conductive in the potential range (vs. Li ^/ Li ⁺ ) of 3 V or more and 4.5 V or less with respect to the oxidation-reduction potential of lithium. Can be done. Examples of the material of the positive electrode terminal include aluminum or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu and Si. The positive electrode terminal is preferably formed of the same material as the positive electrode current collector in order to reduce the contact resistance with the positive electrode current collector.

Next, the secondary battery according to the second embodiment will be described more specifically with reference to the drawings.

FIG. 2 is a cross-sectional view schematically showing an example of the secondary battery according to the second embodiment. FIG. 3 is an enlarged cross-sectional view of part A of the secondary battery shown in FIG.

The secondary battery 100 shown in FIGS. 2 and 3 includes a bag-shaped exterior member 2 shown in FIG. 2, an electrode group 1 shown in FIGS. 2 and 3, and an electrolyte (not shown). The electrode group 1 and the electrolyte are housed in the bag-shaped exterior member 2. The electrolyte (not shown) is held in the electrode group 1.

The bag-shaped exterior member 2 is made of a laminated film containing two resin layers and a metal layer interposed between them.

As shown in FIG. 2, the electrode group 1 is a flat wound type electrode group. As shown in FIG. 3, the flat and wound electrode group 1 includes a negative electrode 3, a separator 4, and a positive electrode 5. The separator 4 is interposed between the negative electrode 3 and the positive electrode 5.

The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode active material-containing layer 3b. As shown in FIG. 3, the negative electrode active material-containing layer 3b is formed only on the inner surface side of the negative electrode current collector 3a in the portion of the negative electrode 3 located in the outermost shell of the wound electrode group 1. In the other portion of the negative electrode 3, negative electrode active material-containing layers 3b are formed on both sides of the negative electrode current collector 3a.

The positive electrode 5 includes a positive electrode current collector 5a and a positive electrode active material-containing layer 5b formed on both surfaces thereof.

As shown in FIG. 2, the negative electrode terminal 6 and the positive electrode terminal 7 are located near the outer peripheral end of the winding type electrode group 1. The negative electrode terminal 6 is connected to a portion located in the outermost shell of the negative electrode current collector 3a. Further, the positive electrode terminal 7 is connected to a portion located in the outermost shell of the positive electrode current collector 5a. These negative electrode terminals 6 and positive electrode terminals 7 extend outward from the opening of the bag-shaped exterior member 2. A thermoplastic resin layer is installed on the inner surface of the bag-shaped exterior member 2, and the opening is closed by heat-sealing the layer.

The secondary battery according to the second embodiment is not limited to the secondary battery having the configuration shown in FIGS. 2 and 3, and may be, for example, the battery having the configuration shown in FIGS. 4 and 5.

FIG. 4 is a partially cutaway perspective view schematically showing another example of the secondary battery according to the second embodiment. FIG. 5 is an enlarged cross-sectional view of portion B of the secondary battery shown in FIG.

The secondary battery 100 shown in FIGS. 4 and 5 includes an electrode group 1 shown in FIGS. 4 and 5, an exterior member 2 shown in FIG. 4, and an electrolyte (not shown). The electrode group 1 and the electrolyte are housed in the exterior member 2. The electrolyte is held in the electrode group 1.

The exterior member 2 is made of a laminated film containing two resin layers and a metal layer interposed between them.

As shown in FIG. 5, the electrode group 1 is a laminated electrode group. The laminated electrode group 1 has a structure in which a negative electrode 3 and a positive electrode 5 are alternately laminated with a separator 4 interposed therebetween.

The electrode group 1 includes a plurality of negative electrodes 3. Each of the plurality of negative electrodes 3 includes a negative electrode current collector 3a and a negative electrode active material-containing layer 3b supported on both sides of the negative electrode current collector 3a. Further, the electrode group 1 includes a plurality of positive electrodes 5. Each of the plurality of positive electrodes 5 includes a positive electrode current collector 5a and a positive electrode active material-containing layer 5b supported on both sides of the positive electrode current collector 5a.

The negative electrode current collector 3a of each negative electrode 3 includes a portion 3c on one side thereof in which the negative electrode active material-containing layer 3b is not supported on any surface. This portion 3c functions as a negative electrode current collecting tab. As shown in FIG. 5, the portion 3c that acts as the negative electrode current collecting tab does not overlap with the positive electrode 5. Further, the plurality of negative electrode current collecting tabs (part 3c) are electrically connected to the strip-shaped negative electrode terminal 6. The tip of the strip-shaped negative electrode terminal 6 is pulled out to the outside of the exterior member 2.

Further, although not shown, the positive electrode current collector 5a of each positive electrode 5 includes a portion on one side thereof in which the positive electrode active material-containing layer 5b is not supported on any surface. This part acts as a positive electrode current collector tab. The positive electrode current collecting tab does not overlap with the negative electrode 3 like the negative electrode current collecting tab (part 3c). Further, the positive electrode current collecting tab is located on the opposite side of the electrode group 1 with respect to the negative electrode current collecting tab (part 3c). The positive electrode current collecting tab is electrically connected to the strip-shaped positive electrode terminal 7. The tip of the strip-shaped positive electrode terminal 7 is located on the opposite side of the negative electrode terminal 6 and is led out to the outside of the exterior member 2.

The secondary battery according to the second embodiment includes the electrodes according to the first embodiment. Therefore, the secondary battery according to the second embodiment is excellent in rate characteristics and energy density.

[Third Embodiment]
According to the third embodiment, an assembled battery is provided. The assembled battery according to the third embodiment includes a plurality of secondary batteries according to the second embodiment.

In the assembled battery according to the third embodiment, each cell may be electrically connected in series or in parallel, or may be arranged in combination with a series connection and a parallel connection.

Next, an example of the assembled battery according to the third embodiment will be described with reference to the drawings.

FIG. 6 is a perspective view schematically showing an example of the assembled battery according to the third embodiment. The assembled battery 200 shown in FIG. 6 includes five cell batteries 100a to 100e, four bus bars 21, a positive electrode side lead 22, and a negative electrode side lead 23. Each of the five cell batteries 100a to 100e is a secondary battery according to the second embodiment.

The bus bar 21 connects, for example, the negative electrode terminal 6 of one cell 100a and the positive electrode 7 of the adjacent cell 100b. In this way, the five cell batteries 100 are connected in series by the four bus bars 21. That is, the assembled battery 200 of FIG. 6 is a 5-series assembled battery. Although not shown in the example, in an assembled battery including a plurality of cells electrically connected in parallel, for example, a plurality of negative electrode terminals are connected by a bus bar and a plurality of positive electrode terminals are connected by a bus bar. As a result, a plurality of cells can be electrically connected.

The positive electrode terminal 7 of at least one of the five cells 100a to 100e is electrically connected to the positive electrode side lead 22 for external connection. Further, the negative electrode terminal 6 of at least one of the five single batteries 100a to 100e is electrically connected to the negative electrode side lead 23 for external connection.

The assembled battery according to the third embodiment includes the secondary battery according to the second embodiment. Therefore, the assembled battery according to the third embodiment is excellent in rate characteristics and energy density.

[Fourth Embodiment]
According to a fourth embodiment, a battery pack is provided. This battery pack includes the assembled battery according to the third embodiment. This battery pack may include a single secondary battery according to the second embodiment instead of the assembled battery according to the third embodiment.

The battery pack according to the fourth embodiment may further include a protection circuit. The protection circuit has a function of controlling charging / discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (for example, an electronic device, an automobile, etc.) may be used as a protection circuit of the battery pack.

Further, the battery pack according to the fourth embodiment may further include an external terminal for energization. The external terminal for energization is for outputting the current from the secondary battery to the outside and / or for inputting the current from the outside to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through an external terminal for energization. Further, when charging the battery pack, the charging current (including the regenerative energy of the power of an automobile or the like) is supplied to the battery pack through an external terminal for energization.

Next, an example of the battery pack according to the fourth embodiment will be described with reference to the drawings.

FIG. 7 is an exploded perspective view schematically showing an example of the battery pack according to the fourth embodiment. FIG. 8 is a block diagram showing an example of the electric circuit of the battery pack shown in FIG. 7.

The battery pack 300 shown in FIGS. 7 and 8 includes a storage container 31, a lid 32, a protective sheet 33, an assembled battery 200, a printed wiring board 34, wiring 35, and an insulating plate (not shown). ..

The storage container 31 shown in FIG. 7 is a bottomed square container having a rectangular bottom surface. The storage container 31 is configured to accommodate the protective sheet 33, the assembled battery 200, the printed wiring board 34, and the wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the storage container 31 to store the assembled battery 200 and the like. Although not shown, the storage container 31 and the lid 32 are provided with an opening, a connection terminal, or the like for connecting to an external device or the like.

The assembled battery 200 includes a plurality of cell cells 100, a positive electrode side lead 22, a negative electrode side lead 23, and an adhesive tape 24.

At least one of the plurality of cell 100 is the secondary battery according to the second embodiment. Each of the plurality of cell 100 is electrically connected in series as shown in FIG. The plurality of cell cells 100 may be electrically connected in parallel, or may be connected in combination with a series connection and a parallel connection. When a plurality of cell 100 are connected in parallel, the battery capacity is increased as compared with the case where a plurality of cell 100s are connected in series.

The adhesive tape 24 fastens a plurality of cell batteries 100. Instead of the adhesive tape 24, a heat shrinkable tape may be used to fix the plurality of cell cells 100. In this case, the protective sheets 33 are arranged on both side surfaces of the assembled battery 200, the heat-shrinkable tape is circulated, and then the heat-shrinkable tape is heat-shrinked to bind the plurality of cells 100.

One end of the positive electrode side lead 22 is connected to the assembled battery 200. One end of the positive electrode side lead 22 is electrically connected to the positive electrode of one or more cell cells 100. One end of the negative electrode side lead 23 is connected to the assembled battery 200. One end of the negative electrode side lead 23 is electrically connected to the negative electrode of one or more cell cells 100.

The printed wiring board 34 is installed along one of the inner side surfaces of the storage container 31 in the short side direction. The printed wiring board 34 includes a positive side connector 342, a negative side connector 343, a thermista 345, a protection circuit 346, wirings 342a and 343a, an external terminal 350 for energization, and positive side wiring (positive side wiring) 348a. And a minus side wiring (negative side wiring) 348b. One main surface of the printed wiring board 34 faces one side surface of the assembled battery 200. An insulating plate (not shown) is interposed between the printed wiring board 34 and the assembled battery 200.

The other end 22a of the positive electrode side lead 22 is electrically connected to the positive electrode side connector 342. The other end 23a of the negative electrode side lead 23 is electrically connected to the negative electrode side connector 343.

The thermistor 345 is fixed to one main surface of the printed wiring board 34. The thermistor 345 detects each temperature of the cell 100 and transmits the detection signal to the protection circuit 346.

The external terminal 350 for energization is fixed to the other main surface of the printed wiring board 34. The external terminal 350 for energization is electrically connected to a device existing outside the battery pack 300. The external terminal 350 for energization includes a positive terminal 352 and a negative terminal 353.

The protection circuit 346 is fixed to the other main surface of the printed wiring board 34. The protection circuit 346 is connected to the positive terminal 352 via the positive wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via the negative side wiring 348b. Further, the protection circuit 346 is electrically connected to the positive electrode side connector 342 via the wiring 342a. The protection circuit 346 is electrically connected to the negative electrode side connector 343 via the wiring 343a. Further, the protection circuit 346 is electrically connected to each of the plurality of cell cells 100 via the wiring 35.

The protective sheet 33 is arranged on both inner side surfaces of the storage container 31 in the long side direction and on the inner side surface in the short side direction facing the printed wiring board 34 via the assembled battery 200. The protective sheet 33 is made of, for example, resin or rubber.

The protection circuit 346 controls the charging / discharging of the plurality of cells 100. Further, the protection circuit 346 is an external terminal for energizing the protection circuit 346 and the external device based on the detection signal transmitted from the thermistor 345 or the detection signal transmitted from the individual cell 100 or the assembled battery 200. The electrical connection with the 350 (positive terminal 352, negative terminal 353) is cut off.

Examples of the detection signal transmitted from the thermistor 345 include a signal for detecting that the temperature of the cell 100 is equal to or higher than a predetermined temperature. Examples of the detection signal transmitted from the individual cell 100 or the assembled battery 200 include signals for detecting overcharge, overdischarge, and overcurrent of the cell 100. When detecting overcharge or the like for each cell 100, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each cell 100.

As the protection circuit 346, a circuit included in a device (for example, an electronic device, an automobile, etc.) that uses the battery pack 300 as a power source may be used.

Further, the battery pack 300 includes an external terminal 350 for energization as described above. Therefore, the battery pack 300 can output the current from the assembled battery 200 to the external device and input the current from the external device to the assembled battery 200 via the external terminal 350 for energization. In other words, when the battery pack 300 is used as a power source, the current from the assembled battery 200 is supplied to the external device through the external terminal 350 for energization. Further, when charging the battery pack 300, a charging current from an external device is supplied to the battery pack 300 through an external terminal 350 for energization. When the battery pack 300 is used as an in-vehicle battery, the regenerative energy of the vehicle power can be used as the charging current from an external device.

The battery pack 300 may include a plurality of assembled batteries 200. In this case, the plurality of assembled batteries 200 may be connected in series, may be connected in parallel, or may be connected by combining series connection and parallel connection. Further, the printed wiring board 34 and the wiring 35 may be omitted. In this case, the positive electrode side lead 22 and the negative electrode side lead 23 may be used as the positive side terminal and the negative side terminal of the external terminal for energization, respectively.

Such a battery pack is used, for example, in an application where excellent cycle performance is required when a large current is taken out. Specifically, this battery pack is used as, for example, a power source for electronic devices, a stationary battery, and an in-vehicle battery for various vehicles. Examples of electronic devices include digital cameras. This battery pack is particularly preferably used as an in-vehicle battery.

The battery pack according to the fourth embodiment includes the secondary battery according to the second embodiment or the assembled battery according to the third embodiment. Therefore, the battery pack according to the fourth embodiment is excellent in rate characteristics and energy density.

[Fifth Embodiment]
According to a fifth embodiment, a vehicle is provided. This vehicle is equipped with the battery pack according to the fourth embodiment.

In the vehicle according to the fifth embodiment, the battery pack recovers, for example, the regenerative energy of the power of the vehicle. The vehicle may include a mechanism (Regenerator) that converts the kinetic energy of the vehicle into regenerative energy.

Examples of vehicles according to the fifth embodiment include two-wheel to four-wheel hybrid electric vehicles, two-wheel to four-wheel electric vehicles, assisted bicycles, and railway vehicles.

The mounting position of the battery pack in the vehicle according to the fifth embodiment is not particularly limited. For example, when the battery pack is mounted in an automobile, the battery pack can be mounted in the engine room of the vehicle, behind the vehicle body, or under the seat.

The vehicle according to the fifth embodiment may be equipped with a plurality of battery packs. In this case, the batteries included in the respective battery packs may be electrically connected in series, electrically connected in parallel, or electrically connected by combining series connection and parallel connection. May be good. For example, when each battery pack contains an assembled battery, the assembled batteries may be electrically connected in series or electrically in parallel, and may be electrically connected by combining series connection and parallel connection. May be connected to. Alternatively, if each battery pack contains a single battery, the batteries may be electrically connected in series, electrically in parallel, or a combination of series and parallel connections. May be electrically connected.

Next, an example of the vehicle according to the fifth embodiment will be described with reference to the drawings.

FIG. 9 is a partial transmission diagram schematically showing an example of the vehicle according to the fifth embodiment.

The vehicle 400 shown in FIG. 9 includes a vehicle body 40 and a battery pack 300 according to a fourth embodiment. In the example shown in FIG. 9, the vehicle 400 is a four-wheeled vehicle.

The vehicle 400 may be equipped with a plurality of battery packs 300. In this case, the batteries included in the battery pack 300 (for example, a single battery or an assembled battery) may be connected in series, may be connected in parallel, or may be connected in combination of series connection and parallel connection.

FIG. 9 illustrates an example in which the battery pack 300 is mounted in an engine room located in front of the vehicle body 40. As described above, the battery pack 300 may be mounted, for example, behind the vehicle body 40 or under the seat. The battery pack 300 can be used as a power source for the vehicle 400. In addition, the battery pack 300 can recover the regenerative energy of the power of the vehicle 400.

Next, an embodiment of the vehicle according to the fifth embodiment will be described with reference to FIG.

FIG. 10 is a diagram schematically showing an example of a control system related to an electric system in a vehicle according to a fifth embodiment. The vehicle 400 shown in FIG. 10 is an electric vehicle.

The vehicle 400 shown in FIG. 10 includes a vehicle body 40, a vehicle power supply 41, a vehicle ECU (Electric Control Unit) 42 which is an upper control device of the vehicle power supply 41, and an external terminal (external). It is provided with a terminal) 43 for connecting to a power source, an inverter 44, and a drive motor 45.

The vehicle 400 mounts the vehicle power supply 41, for example, in the engine room, behind the vehicle body of the vehicle, or under the seat. In the vehicle 400 shown in FIG. 10, the mounting location of the vehicle power supply 41 is schematically shown.

The vehicle power supply 41 includes a plurality of (for example, three) battery packs 300a, 300b, and 300c, a battery management unit (BMU: Battery Management Unit) 411, and a communication bus 412.

The battery pack 300a includes an assembled battery 200a and an assembled battery monitoring device 301a (for example, VTM: Voltage Temperature Monitoring). The battery pack 300b includes an assembled battery 200b and an assembled battery monitoring device 301b. The battery pack 300c includes an assembled battery 200c and an assembled battery monitoring device 301c. The battery packs 300a to 300c are the same battery packs as the above-mentioned battery pack 300, and the assembled batteries 200a to 200c are the same assembled batteries as the above-mentioned assembled battery 200. The assembled batteries 200a to 200c are electrically connected in series. The battery packs 300a, 300b, and 300c can be removed independently and can be replaced with another battery pack 300.

Each of the assembled batteries 200a to 200c includes a plurality of single batteries connected in series. At least one of the plurality of cell cells is the secondary battery according to the second embodiment. The assembled batteries 200a to 200c are charged and discharged through the positive electrode terminal 413 and the negative electrode terminal 414, respectively.

The battery management device 411 communicates with the assembled battery monitoring devices 301a to 301c, and collects information on voltage, temperature, and the like for each of the cell cells 100 included in the assembled batteries 200a to 200c included in the vehicle power supply 41. To do. As a result, the battery management device 411 collects information on the maintenance of the vehicle power supply 41.

The battery management device 411 and the assembled battery monitoring devices 301a to 301c are connected to each other via the communication bus 412. In the communication bus 412, one set of communication lines is shared by a plurality of nodes (battery management device 411 and one or more set battery monitoring devices 301a to 301c). The communication bus 412 is, for example, a communication bus configured based on the CAN (Control Area Network) standard.

The assembled battery monitoring devices 301a to 301c measure the voltage and temperature of the individual cells constituting the assembled batteries 200a to 200c based on a command by communication from the battery management device 411. However, the temperature can be measured at only a few points per set battery, and it is not necessary to measure the temperature of all the cells.

The vehicle power supply 41 may also have an electromagnetic contactor (for example, the switch device 415 shown in FIG. 10) that switches the presence or absence of an electrical connection between the positive electrode terminal 413 and the negative electrode terminal 414. The switch device 415 is a precharge switch (not shown) that is turned on when the assembled batteries 200a to 200c are charged, and is turned on when the output from the assembled batteries 200a to 200c is supplied to the load. Includes a main switch (not shown). Each of the precharge switch and the main switch is provided with a relay circuit (not shown) that is switched on or off by a signal supplied to a coil arranged in the vicinity of the switch element. The magnetic contactor such as the switch device 415 is controlled based on the control signal from the battery management device 411 or the vehicle ECU 42 that controls the operation of the entire vehicle 400.

The inverter 44 converts the input direct current voltage into a high voltage of three-phase alternating current (AC) for driving the motor. The three-phase output terminals of the inverter 44 are connected to the input terminals of each of the three phases of the drive motor 45. The inverter 44 is controlled based on a control signal from the battery management device 411 or the vehicle ECU 42 for controlling the operation of the entire vehicle. By controlling the inverter 44, the output voltage from the inverter 44 is adjusted.

The drive motor 45 is rotated by the electric power supplied from the inverter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and the drive wheels W via, for example, a differential gear unit.

Although not shown, the vehicle 400 is provided with a regenerative braking mechanism (regenerator). The regenerative braking mechanism rotates the drive motor 45 when the vehicle 400 is braked, and converts kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to the inverter 44 and converted into a direct current. The converted direct current is input to the vehicle power supply 41.

One terminal of the connection line L1 is connected to the negative electrode terminal 414 of the vehicle power supply 41. The other terminal of the connection line L1 is connected to the negative electrode input terminal 417 of the inverter 44. The connection line L1 is provided with a current detection unit (current detection circuit) 416 in the battery management device 411 between the negative electrode terminal 414 and the negative electrode input terminal 417.

One terminal of the connection line L2 is connected to the positive electrode terminal 413 of the vehicle power supply 41. The other terminal of the connection line L2 is connected to the positive electrode input terminal 418 of the inverter 44. The connection line L2 is provided with a switch device 415 between the positive electrode terminal 413 and the positive electrode input terminal 418.

The external terminal 43 is connected to the battery management device 411. The external terminal 43 can be connected to, for example, an external power source.

The vehicle ECU 42 cooperatively controls the vehicle power supply 41, the switch device 415, the inverter 44, and the like together with other management devices and control devices including the battery management device 411 in response to an operation input by the driver or the like. By the coordinated control of the vehicle ECU 42 and the like, the output of electric power from the vehicle power supply 41 and the charging of the vehicle power supply 41 are controlled, and the entire vehicle 400 is managed. Data related to the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transferred between the battery management device 411 and the vehicle ECU 42 via a communication line.

The vehicle according to the fifth embodiment is equipped with the battery pack according to the fourth embodiment. Therefore, the vehicle according to the fifth embodiment is excellent in mileage and traveling performance.

(Example 1)
First, the active material, the conductive agent, the binder and the solvent were mixed to prepare a first slurry. As the active material, a powder of lithium cobalt nickel-manganese composite oxide (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) was used. Acetylene black was used as the conductive agent. PVdF was used as the binder. NMP was used as the solvent. The mass ratio of the active material, the conductive agent, and the binder was 90: 5: 5.

Next, the active material, the solid electrolyte, the conductive agent, the binder and the solvent were mixed to prepare a second slurry. As the solid electrolyte, a powder of a garnet-type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ) was used. As the active material, the conductive agent, the binder and the solvent, the same ones as those of the first slurry were used. The mass ratio of the active material, the solid electrolyte, the conductive agent, and the binder was 80: 10: 5: 5.

The first slurry and the second slurry were simultaneously applied onto the current collector so as to be laminated in this order, and dried to obtain a laminated body. As the current collector, an aluminum foil having a thickness of 15 μm was used. The coating amount of the first slurry per unit area was 105 g / m ² . The coating amount of the second slurry per unit area was 45 g / m ² .

The laminate was pressed and cut to a predetermined size. Then, the cut laminate was further vacuum dried to obtain an electrode. The density of the electrodes (excluding the current collector) was 3.0 g / cm ³ .

(Example 2)
Electrodes were produced in the same manner as in Example 1 except that LiNi _0.6 Co _0.2 Mn _0.2 O ₂ was used instead of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as the lithium cobalt nickel-manganese composite oxide.

(Example 3)
Electrodes were produced in the same manner as in Example 1 except that LiNi _0.8 Co _0.1 Mn _0.1 O ₂ was used instead of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as the lithium cobalt nickel-manganese composite oxide.

(Example 4)
Electrodes were produced in the same manner as in Example 1 except that LiNi _0.3 Co _0.4 Mn _0.3 O ₂ was used instead of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as the lithium cobalt nickel-manganese composite oxide.

(Example 5)
An electrode was produced in the same manner as in Example 1 except that the lithium cobalt composite oxide LiCoO ₂ was used instead of the lithium cobalt nickel-manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as the active material.

(Example 6)
As the active material, lithium aluminum manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ was used instead of lithium cobalt nickel manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and the electrode density was 2.6 g / cm ³ An electrode was produced in the same manner as in Example 1 except that.

(Example 7)
As the active material, lithium nickel-nickel-manganese composite oxide LiNi _0.5 Mn _1.5 O ₄ was used instead of Lithium cobalt nickel-manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and the electrode density was 2.6 g / cm. Electrodes were produced in the same manner as in Example 1 except that the value was ³ .

(Example 8)
As an active material, instead of lithium cobalt-nickel-manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O _2, a mixture of lithium cobalt-nickel-manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ and lithium-cobalt composite oxide LiCoO ₂ An electrode was prepared in the same manner as in Example 1 except that it was used.

_{Incidentally, LiNi 0.5 Co 0.2 Mn 0.3 O} 2, LiCoO 2 in the first slurry, a conductive agent, and the mass ratio of the binder is 45: 45: 5: 5. _{Further, LiNi 0.5 Co 0.2 Mn 0.3 O} 2 in the second slurry, LiCoO _2, a solid electrolyte, a conductive agent, and the mass ratio of the binder is 40: 40: 10: 5: 5.

(Example 9)
Similar to Example 8 except that the lithium aluminum manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ was used instead of the lithium cobalt composite oxide LiCoO ₂ and the electrode density was set to 2.8 g / cm ^3. Electrodes were made.

(Example 10)
Example 8 except that the lithium manganese iron-magnesium composite oxide Limn _0.8 Fe _0.15 Mg _0.05 PO ₄ was used instead of the lithium cobalt composite oxide LiCoO ₂ and the electrode density was set to 2.6 g / cm ^3. An electrode was prepared in the same manner as above.

(Example 11)
The mass ratio of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiCoO ₂ , conductive agent, and binder in the first slurry was changed to 80:10: 5: 5, and LiNi _0.5 Co in the second slurry. Electrodes were prepared in the same manner as in Example 8 except that the mass ratios of _0.2 Mn _0.3 O ₂ , LiCoO ₂ , solid electrolyte, conductive agent, and binder were changed to 72: 8: 10: 5: 5. did.

(Example 12)
As the solid electrolyte, a garnet-type lithium aluminum lanthanum zirconium-containing oxide (Li _6.25 Al _0.25 La ₃ Zr ₂ O ₁₂ ) was used instead of the garnet-type lithium aluminum lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ). Except for this, an electrode was prepared in the same manner as in Example 1.

(Example 13)
As the solid electrolyte, NASICON type lithium aluminum titanium-containing oxide (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ) was used instead of the garnet type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ). Except for this, an electrode was prepared in the same manner as in Example 1.

(Example 14)
As the solid electrolyte, NASICON-type lithium zirconium calcium-containing oxide (Li _1.2 Zr _1.9 Ca _0.1 (PO ₄ ) ₃ ) was used instead of the garnet-type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ). Except for this, an electrode was prepared in the same manner as in Example 1.

(Example 15)
Implemented except that perovskite-type lithium lanthanum titanium-containing oxide (Li _0.35 La _0.55 TIO ₃ ) was used instead of the garnet-type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ) as the solid electrolyte. An electrode was prepared in the same manner as in Example 1.

(Example 16)
Electrodes were produced in the same manner as in Example 1 except that the coating amount of the first slurry was 120 g / m ² and the coating amount of the second slurry was 30 g / m ² .

(Example 17)
Electrodes were produced in the same manner as in Example 1 except that the coating amount of the first slurry was 135 g / m ² and the coating amount of the second slurry was 15 g / m ² .

(Comparative Example 1)
Electrodes were produced in the same manner as in Example 1 except that the coating amount of the first slurry was 45 g / m ² and the coating amount of the second slurry was 105 g / m ² .

(Comparative Example 2)
Electrodes were produced in the same manner as in Example 1 except that the coating amount of the first slurry was 75 g / m ² and the coating amount of the second slurry was 75 g / m ² .

(Comparative Example 3)
Electrodes were produced in the same manner as in Example 1 except that the second slurry was used as the first slurry and the first slurry was used as the second slurry.

(Comparative Example 4)
As the active material, lithium aluminum manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ was used instead of lithium cobalt nickel manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and the electrode density was 2.6 g / cm ³ An electrode was produced in the same manner as in Comparative Example 3 except that.

(Comparative Example 5)
Electrodes were produced in the same manner as in Example 1 except that the first slurry was used as the second slurry.

(Comparative Example 6)
An electrode was produced in the same manner as in Example 1 except that the coating amount of the first slurry was set to 150 g / m ² and the coating of the second slurry was omitted.

(Comparative Example 7)
First, a binder was dissolved in a solvent, and then a conductive agent was dispersed to prepare a dispersion. NMP was used as the solvent. PVdF was used as the binder. Acetylene black was used as the conductive agent.

The active material and the solid electrolyte were mixed with this dispersion to obtain a mixed solution. As the active material, a powder of lithium nickel cobalt manganese composite oxide (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) was used. As the solid electrolyte, a powder of a garnet-type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ) was used. A solvent was further added to this mixed solution to obtain a slurry for forming an electrode. The solid content concentration in the slurry was 60% by mass. In the slurry, the mass ratio of the active material, the solid electrolyte, the conductive agent, and the binder was 100: 10: 5: 3.

After applying this slurry on the current collector, the current collector provided with the coating film was introduced into the drying furnace with the coating film as the upper surface. In the drying oven, rapid drying was performed in the first zone at a temperature of 150 ° C. for 1 minute. This rapid drying caused the movement (migration) of the solid electrolyte particles to the surface side in the coating film on the current collector. The remaining zones of the drying oven were dried at 130 ° C. for 2 minutes. The current collector provided with the dried coating film was pressed to obtain electrodes. The electrode density (excluding the current collector) was 3.0 g / cm ³ . In this electrode, the volume ratio of the solid electrolyte particles decreased along the thickness direction of the active material-containing layer. In addition, at least a part of the surface of the active material-containing layer was composed of solid electrolyte particles.

(Example 18)
As the active material, lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) was used instead of lithium cobalt nickel manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and the electrode density was 2.0 g / cm. Electrodes were produced in the same manner as in Example 1 except that the value was ³ .

(Example 19)
Electrodes were produced in the same manner as in Example 18 except that titanium oxide (Tio ₂ (B)) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) as the active material.

(Example 20)
Except for the fact that niobium titanium composite oxide (TiNb ₂ O ₇ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) as the active material, and that the electrode density was 2.5 g / cm ^3. Made an electrode in the same manner as in Example 18.

(Example 21)
As the active material, iron-containing niobium titanium composite oxide (TiNb _1.95 Fe _0.05 O ₇ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ), and the electrode density was 2.5 g / cm ³ An electrode was produced in the same manner as in Example 18 except that.

(Example 22)
As the active material, tantalum-containing niobium titanium composite oxide (TiNb _1.95 Ta _0.05 O ₇ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ), and the electrode density was 2.5 g / cm ³ An electrode was produced in the same manner as in Example 18 except that.

(Example 23)
As the active material, molybdenum-containing niobium titanium composite oxide (TiNb _1.95 Mo _0.05 O ₇ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ), and the electrode density was 2.5 g / cm ³ An electrode was produced in the same manner as in Example 18 except that.

(Example 24)
As the active material, sodium-containing lithium titanium composite oxide (Li ₂ Na ₂ Ti ₆ O ₁₄ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ), and the electrode density was 2.2 g. / cm ³ and to except the were prepared in the same manner as the electrode of example 18.

(Example 25)
As the active material, sodium-containing lithium niobium titanium composite oxide (Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ), and the electrode density was determined. Electrodes were prepared in the same manner as in Example 18 except that the temperature was 2.2 g / cm ³ .

(Example 26)
Electrodes as in Example 18 except that graphite was used instead of lithium-titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) as the active material and the electrode density was 1.2 g / cm ^3. Was produced.

(Example 27)
As the active material, a mixture of graphite and silicon composite oxide (SiO) was used instead of lithium-titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ), and the electrode density was 1.2 g / cm ³ . Electrodes were produced in the same manner as in Example 18 except for the above.

The mass ratio of graphite, SiO, the conductive agent, and the binder in the first slurry was 80: 10: 5: 5. The mass ratio of graphite, SiO, solid electrolyte, conductive agent, and binder in the second slurry was 72: 8: 10: 5: 5.

(Example 28)
As the solid electrolyte, a garnet-type lithium aluminum lanthanum zirconium-containing oxide (Li _6.25 Al _0.25 La ₃ Zr ₂ O ₁₂ ) was used instead of the garnet-type lithium aluminum lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ). Except for this, an electrode was prepared in the same manner as in Example 18.

(Example 29)
As the solid electrolyte, NASICON type lithium aluminum titanium-containing oxide (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ) was used instead of the garnet type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ). Except for this, an electrode was prepared in the same manner as in Example 18.

(Example 30)
As the solid electrolyte, NASICON-type lithium zirconium calcium-containing oxide (Li _1.2 Zr _1.9 Ca _0.1 (PO ₄ ) ₃ ) was used instead of the garnet-type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ). Except for this, an electrode was prepared in the same manner as in Example 18.

(Example 31)
Implemented except that perovskite-type lithium lanthanum titanium-containing oxide (Li _0.35 La _0.55 TIO ₃ ) was used instead of the garnet-type lithium lanthanum zirconium-containing oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ) as the solid electrolyte. An electrode was prepared in the same manner as in Example 18.

(Example 32)
Use as an active material, instead of the lithium-titanium composite oxide (Li ₄ Ti ₅ O _12), lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂₎ and titanium oxide A mixture of (TiO ₂ (B)) An electrode was prepared in the same manner as in Example 18 except that it was present.

The mass ratio of Li ₄ Ti ₅ O ₁₂ , TiO ₂ (B), the conductive agent, and the binder in the first slurry was set to 45:45: 5: 5. The mass ratio of Li ₄ Ti ₅ O ₁₂ , TiO ₂ (B), solid electrolyte, conductive agent, and binder in the second slurry was set to 40:40: 10: 5: 5.

(Example 33)
Except for the fact that niobium-titanium composite oxide (TiNb ₂ O ₇ ) was used instead of titanium oxide (TiO ₂ (B)) as the active material and that the electrode density was set to 2.3 g / cm ³ . An electrode was produced in the same manner as in Example 32.

(Example 34)
As the active material, sodium-containing lithium niobium titanium composite oxide (Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ ) was used instead of titanium oxide (TiO ₂ (B)), and the electrode density was 2. Electrodes were produced in the same manner as in Example 32, except that the value was 1 g / cm ³ .

(Example 35)
As the active material, sodium-containing lithium niobium titanium composite oxide (Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ ) was used instead of titanium oxide (TiO ₂ (B)), and the electrode density was 2. Electrodes were produced in the same manner as in Example 32, except that the value was 1 g / cm ³ .

The mass ratio of Li ₄ Ti ₅ O ₁₂ , Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ , the conductive agent, and the binder in the first slurry was 80: 10: 5: 5. The mass ratio of Li ₄ Ti ₅ O ₁₂ , Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ , solid electrolyte, conductive agent, and binder in the second slurry was 71: 8: 10: 5: 5. ..

(Example 36)
Electrodes were produced in the same manner as in Example 18 except that the coating amount of the first slurry was 120 g / m ² and the coating amount of the second slurry was 30 g / m ² .

(Example 37)
Electrodes were produced in the same manner as in Example 18 except that the coating amount of the first slurry was 135 g / m ² and the coating amount of the second slurry was 15 g / m ² .

(Comparative Example 8)
Electrodes were produced in the same manner as in Example 18 except that the coating amount of the first slurry was 45 g / m ² and the coating amount of the second slurry was 105 g / m ² .

(Comparative Example 9)
Electrodes were produced in the same manner as in Example 18 except that the second slurry was used as the first slurry and the first slurry was used as the second slurry.

(Comparative Example 10)
Except for the fact that niobium titanium composite oxide (TiNb ₂ O ₇ ) was used instead of lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) as the active material, and that the electrode density was 2.5 g / cm ^3. Made an electrode in the same manner as in Comparative Example 9.

(Comparative Example 11)
Electrodes were produced in the same manner as in Example 18 except that the first slurry was used as the second slurry.

(Comparative Example 12)
An electrode was produced in the same manner as in Example 18 except that the coating amount of the first slurry was set to 150 g / m ² and the coating of the second slurry was omitted.

(Comparative Example 13)
As the active material, lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) was used instead of lithium cobalt nickel manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and the electrode density was 2.0 g / cm. Electrodes were produced in the same manner as in Comparative Example 7 except that the value was ³ . In this electrode, the volume ratio of the solid electrolyte particles decreased along the thickness direction of the active material-containing layer. In addition, at least a part of the surface of the active material-containing layer was composed of solid electrolyte particles.

(Example 38)
The non-aqueous electrolyte batteries shown in FIGS. 2 and 3 were obtained by the following methods.
First, the positive electrode, the first separator, the negative electrode, and the second separator were laminated in this order to obtain a laminated body. After winding this laminated body in a spiral shape, a press treatment was performed at a temperature of 90 ° C. to prepare a flat electrode group. The width of the flat electrode group was 30 mm, and the thickness was 3.0 mm. As the positive electrode, the electrode obtained in Example 1 was used. As the negative electrode, the electrode obtained in Example 18 was used. As the first and second separators, polyethylene porous films having a thickness of 25 μm were used.

Next, the flat electrode group was housed in a pack made of a laminated film, and then vacuum dried at a temperature of 80 ° C. for 24 hours. The laminated film was formed by forming polypropylene layers on both sides of an aluminum foil having a thickness of 40 μm, and had an overall thickness of 0.1 mm.

After injecting a liquid non-aqueous electrolyte into the vacuum-dried laminated film pack, the pack was completely sealed by heat sealing. As the liquid non-aqueous electrolyte, one in which the electrolyte was dissolved in a mixed solvent at a concentration of 1 M was used. As the mixed solvent, a mixture of propylene carbonate (PC) and diethyl carbonate (DEC) in a volume ratio of 1: 1 was used. LiPF ₆ was used as the electrolyte.

In this way, the non-aqueous electrolyte batteries shown in FIGS. 2 and 3 were obtained. The width of the non-aqueous electrolyte battery was 35 mm, the thickness was 3.2 mm, and the height was 65 mm. The capacity of the non-aqueous electrolyte battery was 500 mAh.

(Example 39)
A non-aqueous electrolyte battery was obtained in the same manner as described in Example 38, except that the electrode obtained in Comparative Example 12 was used as the negative electrode.

(Example 40)
A non-aqueous electrolyte battery was obtained in the same manner as described in Example 38, except that the electrode obtained in Comparative Example 6 was used as the positive electrode.

(Example 41)
A non-aqueous electrolyte battery was obtained in the same manner as described in Example 38, except that the electrode obtained in Example 8 was used as the positive electrode.

(Example 42)
A non-aqueous electrolyte battery was obtained in the same manner as described in Example 38, except that the electrode obtained in Example 32 was used as the negative electrode.

(Comparative Example 14)
Non-aqueous in the same manner as described in Example 38, except that the electrode obtained in Comparative Example 6 was used as the positive electrode and the electrode obtained in Comparative Example 12 was used as the negative electrode. Obtained an electrolyte battery.

(Comparative Example 15)
Non-aqueous in the same manner as described in Example 38, except that the electrode obtained in Comparative Example 3 was used as the positive electrode and the electrode obtained in Comparative Example 12 was used as the negative electrode. Obtained an electrolyte battery.

(Comparative Example 16)
Non-aqueous in the same manner as described in Example 38, except that the electrode obtained in Comparative Example 6 was used as the positive electrode and the electrode obtained in Comparative Example 9 was used as the negative electrode. Obtained an electrolyte battery.

<Various measurements>
By the method described above, the thickness T of the active material-containing layer, the length L1 of the first active material part, the length L2 of the second active material part, the ratio L1 / T, and the solid per unit area of the first active material part. Content of electrolyte particles E1, content of solid electrolyte particles per unit area of the second active material part E2, content of active material particles per unit area of the first active material part E3, unit of the second active material part The content E4, the ratio E1 / E2, and the uniformity of the active material particles per area were calculated.

In Comparative Examples 7 and 13, the solid electrolyte particles per unit area obtained for the cross section parallel to the deepest surface obtained by cutting a part of the active material-containing layer having a thickness of 5 μm from the deepest surface. The content was defined as the content E1. Further, the content of solid electrolyte particles per unit area obtained for a cross section parallel to the outermost surface obtained by cutting a part of an active material-containing layer having a thickness of 5 μm from the outermost surface is defined as the content E2. did.

The results are shown in Tables 3 and 4.

<Rate characteristics>
The rate characteristics were evaluated using the electrodes obtained in Examples 1-37 and Comparative Examples 1-13. Specifically, first, a triode cell was produced. The electrodes obtained in Examples 1 to 37 and Comparative Examples 1 to 13 were used as the working electrodes of the three-pole cell. Lithium metal was used as the counter electrode and the reference electrode of the 3-pole cell. As the non-aqueous electrolyte, one in which LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) was used. The volume ratio of EC to DEC in the mixed solvent was 1: 2. The concentration of LiPF ₆ was 1.0 mol / L.

Next, constant current and constant voltage charging was performed at a temperature of 25 ° C. Examples 1 to 6, 8 to 17 and Comparative Examples 1 to 7 are charged to a voltage of 4.3 V at a current value of 1 C, and Example 7 is charged to a voltage of 4.9 V at a current value of 1 C to a predetermined voltage. The constant voltage charging was performed until the current value reached 0.05 C. Examples 18 to 25, 28 to 37 and Comparative Examples 8 to 13 are charged to a voltage of 1.0 V at a current value of 1 C, and Examples 26 and 27 are charged to a voltage of 0.05 V at a current value of 1 C. Constant voltage charging was performed until the current value reached 0.05 C in voltage. After charging, Examples 18 to 37 and Comparative Examples 8 to 13 have a current value of 0.2 C until they reach 3.2 V at a current value of 0.2 C in Examples 1 to 17 and Comparative Examples 1 to 7. The cell was discharged until it reached 0 V. The discharge capacity obtained at this time was defined as the discharge capacity W1.

Next, Examples 1 to 6, 8 to 17 and Comparative Examples 1 to 7 are charged with a current value of 1C of 4.3V, and Example 7 is charged with a current value of 1C until a voltage of 4.9V is reached. Constant voltage charging was performed until the current value reached 0.05 C at the voltage of. Examples 18 to 25, 28 to 37 and Comparative Examples 8 to 13 are charged to a voltage of 1.0 V at a current value of 1 C, and Examples 26 and 27 are charged to a voltage of 0.05 V at a current value of 1 C. The cell was recharged with a voltage of 0.05 C. After charging, Examples 1 to 17 and Comparative Examples 1 to 7 reach 3.2 V at a current value of 10 C, and Examples 18 to 37 and Comparative Examples 8 to 13 reach 3.0 V at a current value of 10 C. The cell was discharged. The discharge capacity obtained at this time was defined as the discharge capacity W2.
The discharge capacity W2 / W1 was obtained by dividing the discharge capacity W2 by the discharge capacity W1.

The non-aqueous electrolyte batteries obtained in Examples 38 to 42 and Comparative Examples 14 to 15 were evaluated in the same manner at a temperature of 25 ° C. Charging was constant current constant voltage charging, constant current charging was performed up to 2.8 V with a current value of 1 C, and after reaching 2.8 V, constant voltage charging was performed until the current value reached 0.05 C. The discharge was a constant current discharge of 0.2 C or 10 C at a temperature of 25 ° C. The discharge was carried out until the cell voltage became 1.5 V. From the obtained values, the discharge capacity ratio W2 / W1 was calculated.
The results are shown in Tables 3, 4 and 5.

<Measurement of energy density>
For the electrodes obtained in Examples 1 to 37 and Comparative Examples 1 to 13, the capacity per weight of the active material-containing layer at the time of 0.2C discharge was defined as the energy density (mAh / g). From Tables 3 and 4 below, it can be seen that when the same active material is compared, the energy density in the examples is higher than that in the comparative example. This is because the amount and the presence position of the solid electrolyte particles are optimized, and it is shown that the energy density and the rate characteristics can be compatible with each other without excessively containing the solid electrolyte particles in the electrode layer.
The results are shown in Table 2.

The methods for manufacturing the electrodes according to the examples and comparative examples are summarized in Tables 1 and 2 below.

In Tables 1 and 2 above, the types of active materials are described in the columns described as "first active material" and "second active material". The column labeled "Solid Electrolyte" describes the type of solid electrolyte. In the column labeled "1st mass ratio", the mass ratios of the first active material, the second active material, the solid electrolyte, the conductive agent, and the binder in the first slurry are described. The column labeled "second mass ratio" describes the mass ratio of the first active material, the second active material, the solid electrolyte, the conductive agent, and the binder in the second slurry. In the column described as "first coating amount", the coating amount of the first slurry per unit area of the current collector is described. In the column described as "second coating amount", the coating amount of the second slurry per unit area of the current collector is described.

The characteristics of the electrodes according to the examples and comparative examples are summarized in Tables 3 and 4 below.

In Tables 3 and 4 above, the column labeled "Thickness T" indicates the thickness of the active material-containing layer. In the column described as "length L1", the length of the first active material portion along the first direction, which is a direction parallel to the thickness direction of the active material-containing layer, is described. In the column described as "length L2", the length of the second active material portion along the first direction, which is a direction parallel to the thickness direction of the active material-containing layer, is described. In the column described as "L1 / T", the ratio of the length L1 of the first active material portion to the thickness T of the active material-containing layer is described. In "Content E1" and "Content E2", the contents of the solid electrolyte particles per unit area in the first active material part and the second active material part are described, respectively. In "content E3" and "content E4", the contents of the active material particles per unit area in the first active material part and the second active material part are described, respectively. The column labeled "E1 / E2" describes the ratio of the content E1 to the content E2. In the column labeled "uniformity", it is described whether or not the solid electrolyte particles are uniformly dispersed in the first and second active material parts. In the column labeled "Density", the density of the active material-containing layer is described. In the column described as "discharge capacity ratio", the discharge capacity when discharged at a current value of 10 C with respect to the discharge capacity when discharged at a current value of 0.2 C is described. In the column labeled "Energy Density", the weight energy density of the electrodes is listed.

The characteristics of the non-aqueous electrolyte battery according to Examples and Comparative Examples are summarized in Table 5 below.

As is clear from the comparison between Example 1 and Comparative Examples 1 and 2, the comparison between Example 6 and Comparative Example 4, and the comparison between Example 18 and Comparative Examples 8 and 9, the first active material part An electrode having a length of 0.7 T or more and a content E1 / E2 of 0.01 or less has both a high discharge capacity rate and an energy density as compared with an electrode that does not meet any of these requirements. Was done. Further, as is clear from the comparison between Example 1 and Comparative Example 3 and the comparison between Example 18 and Comparative Example 10, the length of the first active material portion is 0.7 T or more, and the content E1. An electrode having a / E2 of 0.01 or less was able to achieve both a higher discharge capacity rate and an energy density as compared with an electrode that did not meet these requirements.

Further, as shown in Examples 2 to 11, 19 to 27, and 32 to 35, it was possible to achieve both a high discharge capacity ratio and an energy density even when the type of active material was changed. Further, as shown in Examples 12 to 15 and 28 to 31, it was possible to achieve both a high discharge capacity rate and an energy density even when the types of the solid electrolyte particles were changed.

Further, the electrodes according to Comparative Examples 7 and 13 could not achieve both a high discharge capacity ratio and an energy density. The reason for this is that it is important that the solid electrolyte exists on the separator side of the electrode layer in order to improve the rate characteristics, but in Comparative Examples 7 and 13, not only the surface side of the electrode layer but also the collection of the electrode layers. It is probable that the energy density decreased, although a certain improvement in the rate characteristics was observed because the density gradient was applied to the electric foil side.

The electrode according to at least one embodiment described above has a second active material portion containing solid electrolyte particles and a second active material portion having a smaller content of solid electrolyte particles as compared with the second active material portion or containing no solid electrolyte particles. 1 Includes active material part. Therefore, when this electrode is used, a secondary battery having excellent rate characteristics and energy density can be realized.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Electrode group, 2 ... Exterior member, 3 ... Negative electrode, 3a ... Negative electrode current collector, 3b ... Negative electrode active material-containing layer, 3c ... Negative electrode current collector tab, 4 ... Separator, 5 ... Positive electrode, 5a ... Positive electrode current collector 5, 5b ... positive electrode active material-containing layer, 6 ... negative electrode terminal, 7 ... positive electrode terminal, 21 ... bus bar, 22 ... positive electrode side lead, 22a ... other end, 23 ... negative electrode side lead, 23a ... other end, 24 ... adhesive tape, 31 ... storage container, 32 ... lid, 33 ... protective sheet, 34 ... printed wiring board, 35 ... wiring, 40 ... vehicle body, 41 ... vehicle power supply, 42 ... electric control device, 43 ... external terminal, 44 ... inverter, 45 ... drive motor, 100 ... secondary battery, 200 ... assembled battery, 200a ... assembled battery, 200b ... assembled battery, 200c ... assembled battery, 300 ... battery pack, 300a ... battery pack, 300b ... battery pack, 300c ... battery pack , 301a ... Assembly battery monitoring device, 301b ... Assembly battery monitoring device, 301c ... Assembly battery monitoring device, 342 ... Positive electrode side connector, 343 ... Negative electrode side connector, 345 ... Thermista, 344 ... Protection circuit, 342a ... Wiring, 343a ... Wiring , 350 ... External terminal for energization, 352 ... Positive terminal, 353 ... Negative terminal, 348a ... Positive side wiring, 348b ... Negative side wiring, 400 ... Vehicle, 411 ... Battery management device, 412 ... Communication bus, 413 ... Positive electrode terminal, 414 ... Negative electrode terminal, 415 ... Switch device, 416 ... Current detector, 417 ... Negative electrode input terminal, 418 ... Positive electrode input terminal, L1 ... Connection line, L2 ... Connection line, W ... Drive wheel.

Claims (15)

A current collector and an active material-containing layer provided on the current collector are provided.
The active material-containing layers are laminated with each other along the thickness direction, and include a first active material portion and a second active material portion containing active material particles, respectively.
The first active material section is located between the current collector and the second active material section, and is the length of the first active material section along the first direction parallel to the thickness direction. The dimension is in the range of 0.7T or more and 0.95T or less with respect to the thickness T of the active material-containing layer.
The second active material portion further contains solid electrolyte particles and contains
The ratio E1 / E2 of the content E1 (including 0) of the solid electrolyte particles per unit area of the first active material part and the content E2 of the solid electrolyte particles per unit area of the second active material part is , 0 or more and 0.01 or less. The electrode according to claim 1, wherein the active material particles and the solid electrolyte particles are uniformly mixed in the second active material part. The electrode according to claim 1 or 2, wherein the content E1 of the solid electrolyte particles per unit area of the first active material portion is 0.1 atm% or less (including 0). The electrode according to any one of claims 1 to 3, wherein the content E2 of the solid electrolyte particles per unit area of the second active material portion is 7 atm% or more and 20 atm% or less. The electrode according to any one of claims 1 to 4, wherein the content of the active material particles per unit area of the first active material part is 50 atm% or more and 90 atm% or less. The electrode according to any one of claims 1 to 5, wherein the content of the active material particles per unit area of the second active material part is 30 atm% or more and 85 atm% or less. The active material particles include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, lithium manganese nickel composite oxide, lithium manganese cobalt composite oxide, and iron lithium phosphate. The electrode according to any one of claims 1 to 6, which comprises at least one selected from the group consisting of lithium nickel cobalt manganese composite oxide. The active material particle according to any one of claims 1 to 6, which contains at least one selected from the group consisting of titanium dioxide, titanium composite oxide, niobium titanium composite oxide, and sodium-containing titanium composite oxide. Electrodes. The solid electrolyte particles are at least one selected from the group consisting of perovskite-type lithium lanthanum titanium-containing oxides, garnet-type lithium lanthanum zirconium-containing oxides, NASICON-type lithium aluminum titanium-containing oxides, and lithium calcium zirconium-containing oxides. The electrode according to any one of claims 1 to 8, which comprises. It has a positive electrode, a negative electrode, and an electrolyte.
A secondary battery in which at least one of the positive electrode and the negative electrode is the electrode according to any one of claims 1 to 9. A battery pack comprising the secondary battery according to claim 10. With an external terminal for energizing
The battery pack according to claim 11, further comprising a protection circuit. Equipped with the plurality of the secondary batteries
The battery pack according to claim 11 or 12, wherein the secondary batteries are electrically connected in series, in parallel, or in series and in parallel. A vehicle equipped with the battery pack according to any one of claims 11 to 13. The vehicle according to claim 14, further comprising a mechanism for converting the kinetic energy of the vehicle into regenerative energy.