JP2016018704A - All solid battery - Google Patents

Abstract

An object of the present invention is to suppress an increase in the temperature of a central portion in an all solid state battery. An all solid state battery includes a battery element including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. The all-solid-state battery is configured such that the amount of heat generated at the center of the battery element during charge / discharge is smaller than the amount of heat generated at the outer periphery of the battery element. [Selection] Figure 1

Description

  The present invention relates to an all solid state battery.

  Lithium batteries are used in various fields such as automobiles and portable devices because they have characteristics such as high voltage and energy density and low memory effect. As its use progresses, further improvements in performance and safety are desired for lithium batteries.

  As a method for improving performance and safety, an all-solid battery using a solid electrolyte instead of an organic solvent electrolyte has been studied. The all solid state battery includes a negative electrode, a positive electrode, and a solid electrolyte sandwiched between the negative electrode and the positive electrode. The negative electrode, the solid electrolyte, and the positive electrode are laminated in this order, and pressure is applied from both sides as necessary. For example, Patent Document 1 discloses an all-solid battery that applies a pressure of 1.5 to 200 MPa. This patent document 1 is intended to make it possible to apply uniform pressure to the entire surface of the solid electrolyte layer, to suppress the swelling of the battery at the center of the battery, and to increase the ionic conductivity.

JP 2008-103284 A

  When pressure is uniformly applied to the entire surface of the solid electrolyte layer of the all-solid-state battery as in Patent Document 1, it is considered that bonding at the electrode-solid electrolyte interface can be improved, and deterioration of battery characteristics due to poor contact can be suppressed. However, the center part and the outer peripheral part of the all-solid-state battery are different in heat dissipation performance, that is, heat dissipation, and the outer peripheral part is more likely to dissipate heat than the central part. Therefore, heat is dissipated at the outer peripheral portion and the temperature is lowered, but heat is not dissipated so much at the central portion and the temperature is increased. If so, there is a risk that the central electrode and the solid electrolyte having a high temperature deteriorate. Therefore, a technique capable of making the temperature difference between the central portion and the outer peripheral portion smaller in the all-solid battery than in the prior art is desired.

  According to the present invention, there is provided an all-solid battery comprising a battery element including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. An all-solid-state battery is provided that is configured such that the amount of heat generated at the center is smaller than the amount of heat generated at the outer periphery of the battery element.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature difference of a center part and an outer peripheral part in an all-solid-state battery can be made smaller than before.

FIG. 1 is a schematic side view illustrating a configuration example of an all-solid battery according to an embodiment. FIG. 2 is a schematic plan view showing a configuration example of the all solid state battery according to the embodiment. FIG. 3 is a schematic diagram showing the relationship between the central portion and the outer peripheral portion of the battery element. FIG. 4 is a graph conceptually showing the pressure distribution and IV resistance distribution of a conventional battery element. FIG. 5 is a graph conceptually showing a calorific value distribution and a temperature distribution of a conventional battery element. FIG. 6 is a graph conceptually showing the pressure distribution and IV resistance distribution of the battery element according to the present embodiment. FIG. 7 is a graph conceptually showing the calorific value distribution and temperature distribution of the battery element according to the present embodiment. FIG. 8 is a graph showing the relationship between the binding force and the battery resistance in the example.

  According to the present invention, there is provided an all-solid battery comprising a battery element including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. An all-solid-state battery is provided that is configured such that the amount of heat generated at the center is smaller than the amount of heat generated at the outer periphery of the battery element.

  According to such an all-solid-state battery, at the time of charging / discharging, the amount of heat generated at the central portion where it is difficult to release heat to the outside is smaller than the amount of heat generated at the outer peripheral portion where heat is easily released to the outside. It can suppress that the temperature of a center part rises rather than temperature of this. That is, since the outer peripheral portion easily releases heat to the outside, the temperature is likely to decrease even if the amount of heat generation is large, and the central portion has a small amount of heat generation, so that an increase in temperature can be suppressed even if it is difficult to release heat to the outside. Therefore, the temperature can be made uniform in the in-plane direction of the battery element. However, the “all-solid battery” in the present invention means a battery in which each element constituting the battery element such as the positive electrode, the negative electrode, and the electrolyte is solid. Further, the “outer peripheral portion” in the battery element is a region in the vicinity of the outer peripheral edge along the outer peripheral edge in the plane of the battery element. When the “peripheral part” is rectangular, the “peripheral part” is exemplified by a band-like region having a width of about 30 to 30% of the horizontal width and a width of about 10 to 30% of the vertical width. It may be a region having a width of 5 to 1.5 cm. The “central part” in the battery element is an inner region surrounded by the outer peripheral part in the plane of the battery element. The “central portion” may be a region in the vicinity of the center, for example, a region having a width of about 10 to 80% of the horizontal width including the center and a width of about 10 to 80% of the vertical width.

  As an example of a configuration in which the calorific value at the central part of the battery element is smaller than the calorific value at the outer peripheral part of the battery element, for example, pressure (binding force) applied to the central part of the battery element is applied to the outer peripheral part. There is a method of using a restraining member that restrains the battery element so as to be larger than the pressure (restraint force). For example, the pressure at the center can be 15 MPa or more, and the pressure at the outer periphery can be less than 15 MPa. The pressure at the center is preferably 2 times or more, more preferably 3 times or more than the pressure at the outer periphery. The upper limit of the pressure difference between the central portion and the outer peripheral portion is preferably 10 times or less.

  Hereinafter, an all-solid battery according to an embodiment of the present invention will be described with reference to the drawings.

  1 and 2 are a schematic side view and a schematic plan view showing a configuration example of the all solid state battery A according to the present embodiment, respectively. The all solid state battery A includes a battery element 1 and a restraining member 2.

  The battery element 1 is a chargeable / dischargeable cell, and includes a positive electrode 11, a negative electrode 12, and a solid electrolyte layer 13 that is disposed between the positive electrode 11 and the negative electrode 12 and contains a solid electrolyte. The positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13 are formed of solid. The positive electrode 11 includes a positive electrode active material layer 14 including a positive electrode mixture and a positive electrode current collector 16 that collects current from the positive electrode active material layer 14. The negative electrode 12 includes a negative electrode active material layer 15 including a negative electrode mixture; And a negative electrode current collector 17 for collecting current of the negative electrode active material layer 15.

  The restraining member 2 applies the pressure from the positive electrode 11 side and the negative electrode 12 side of the battery element 1 in the direction perpendicular to the laminate surface of the laminate including the positive electrode 11, the solid electrolyte layer 13, and the negative electrode 12, thereby to bound. The restraining member 2 includes restraining plates 23, 22, 24, a connecting rod 21, and nuts 26, 25, 27.

  The restraint plate 23 supports and restrains the battery element 1 from the negative electrode 12 side, and the restraint plate 22 supports and restrains the battery element 1 from the positive electrode 11 side. In other words, the battery element 1 is sandwiched between the restraining plate 23 and the restraining plate 22. The restraint plate 24 is disposed on the side of the restraint plate 22 opposite to the side in contact with the battery element 1. The restraint plate 24 includes a plate portion 24a similar to the restraint plate 22 and the restraint plate 23, and a protruding portion 24b provided at the center of the plate portion 24a and projecting from the plate portion 24a toward the battery element 1 side. The protruding portion 24 b is in contact with the central portion of the restraining plate 22. However, the restraint plate 24 may be disposed on the side of the restraint plate 23 opposite to the side in contact with the battery element 1, and in this case, the protruding portion 24 b is in contact with the central portion of the restraint plate 23. The plate portion 24a and the protruding portion 24b may be separate.

  The connecting rod 21 passes through holes provided in the restraining plates 23, 22, and 24. The nuts 26, 25, and 27 fix the restraining plates 23, 22, and 24 to desired positions of the connecting rod 21, respectively. Depending on the tightening positions of the nuts 26 and 25, the force with which the restraining plates 23 and 22 sandwich the battery element 1, that is, the pressure applied to the entire battery element 1 is set. Depending on the tightening position of the nut 27, the force by which the protruding portion 24 b of the restraint plate 24 pushes the central portion of the restraint plate 22, that is, the pressure applied to the central portion of the battery element 1 is set.

  Here, the restraint plate 24 is made of a highly rigid material that can push the protruding portion 24 b into the central portion of the restraint plate 22 by tightening the nut 27. For example, a metal material, a ceramic material, or a resin material is exemplified. The restraint plate 22 is made of a material that can be elastically deformed by the force of the protruding portion 24 b and apply pressure to the central portion of the battery element 1. For example, a resin material or a metal material is exemplified. The degree of elastic deformation can be adjusted not only by selecting the material but also by selecting the thickness. The restraint plate 23 is made of a highly rigid material that does not deform even when the pressure at the center of the battery element 1 is high due to deformation of the restraint plate 22. For example, a metal material, a ceramic material, or a resin material is exemplified. In terms of hardness, it can be said that the restraint plates 24 and 23 are relatively hard and the restraint plate 22 is relatively soft.

  For example, when the tightening of the nut 27 is increased, the force with which the protruding portion 24 b of the restraint plate 24 pushes the central portion of the restraint plate 22 increases. As a result, the central portion of the restraining plate 22 is strongly pressed, and the pressure applied to the central portion of the battery element 1 increases. As a result, the pressure applied to the central part of the battery element 1 is set higher than the pressure applied to the outer peripheral part of the battery element 1. However, the structure which pushes the center part of the battery element 1 in the restraint member 2 is an example, and if it can push the center part of the battery element 1, it will not be limited to the said example.

  FIG. 3 is a schematic diagram showing the relationship between the central portion and the outer peripheral portion of the battery element 1. This figure shows the battery element 1 viewed from the stacking direction, and the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13 in the battery element 1 are collectively shown as an element 30.

  In the following description, as the outer peripheral portion 32 of the battery element 1, a region along the outer peripheral edge of the element 30 (the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13) of the battery element 1, for example, a vertical width (longitudinal length) Let us consider a band-like region having a width of about 10 to 30% from both ends of the width L1) and a width of about 10 to 30% from both ends of the lateral width (lateral length L2). Further, as the central portion 31 of the battery element 1, a region including the center 31a of the element 30 of the battery element 1, that is, a center 31a of about 10 to 40% of the width from the center 31a of the longitudinal width to both ends and the center 31a of the lateral width. Consider a substantially rectangular region having a width of about 10 to 40% from the center to both ends. In addition, the area | region of these outer peripheral parts 32 and the center part 31 is an illustration, and even if it has another shape, an essential function is the same.

Next, the calorific value and temperature in the conventional battery element will be described.
FIG. 4 is a graph conceptually showing the pressure distribution and IV resistance distribution of a conventional battery element. This figure shows an example of pressure distribution and resistance distribution when the battery element is viewed from the side. However, the left vertical axis represents pressure (MPa), the right vertical axis represents IV resistance (surface resistance: Ω · cm ² ), and the horizontal axis represents the in-plane position.

  In a battery element such as Patent Document 1, as shown by a straight line P1, pressure is uniformly applied to the entire surface (PCON1). That is, the pressure applied to the central portion of the battery element is substantially the same as the pressure applied to the outer peripheral portion. In such a case, as indicated by the straight line R1, the IV resistance is uniform over the entire surface of the battery element (RCON1). That is, the IV resistance at the center of the battery element is substantially the same as the IV resistance at the outer periphery.

An example of the calorific value distribution and temperature distribution of the battery element at that time is conceptually shown in FIG. The left vertical axis indicates the temperature of the battery element, the right vertical axis indicates the amount of heat generated by the battery element, and the horizontal axis indicates the in-plane position. Here, in general, the relationship between resistance and calorific value is represented by Q = RI ² t (where Q: Joule heat, R: resistance, I: current, t: time). When this is applied to the battery element, the heat generation amount is proportional to the IV resistance if the current density is constant between the central portion and the outer peripheral portion. Therefore, if the in-plane distribution of the IV resistance is uniform (straight line R1: RCON1), the in-plane distribution of the heat generation amount is uniform (QCON1) as shown by the straight line A1.

  At that time, heat is dissipated in the outer peripheral portion having high heat dissipation and the temperature is lowered, but heat is hardly dissipated in the central portion having low heat dissipation and the temperature remains high. That is, as shown in the curve B1, the in-plane distribution of the temperature of the battery element has the maximum temperature TMAX1 at the center, the temperature decreases toward the outer periphery, and the minimum temperature TMIN1 at the outer periphery. At this time, the temperature difference Δ1 = TMAX1-TMIN1 between the central portion and the outer peripheral portion is a relatively large value, for example, a temperature difference of 3 ° C. or more.

Next, the heat generation amount and temperature in the battery element according to the present embodiment will be described.
FIG. 6 is a graph conceptually showing the pressure distribution and the resistance distribution applied to the battery element. This figure shows an example of pressure distribution and resistance distribution when the battery element is viewed from the side. However, the left vertical axis represents pressure (MPa), the right vertical axis represents IV resistance (surface resistance: Ω · cm ² ), and the horizontal axis represents the in-plane position.

  In the battery element 1 of the present embodiment, the pressure applied to the central part 31 of the battery element 1 is set higher than the pressure applied to the outer peripheral part 32 by the restraining member 2 as shown by the curve P2. Yes. That is, the pressure applied to the battery element 1 (element 30 thereof) reaches the maximum pressure PMAX2 at the central portion 31, decreases toward the outer peripheral portion 32, and reaches the minimum pressure PMIN2 at the outer peripheral portion 32. In other words, in the all solid state battery A, the restraining force is inclined so that the restraining force of the central portion 31 is stronger than the restraining force of the outer peripheral portion 32. In such a case, as indicated by the curve R2, the IV resistance of the central portion 31 of the battery element 1 is lower than the IV resistance of the outer peripheral portion 32. That is, the IV resistance of the battery element 1 becomes the minimum resistance RMIN2 at the central portion 31, increases toward the outer peripheral portion 32, and becomes the maximum resistance RMAX2 at the outer peripheral portion 32.

An example of the calorific value distribution and temperature distribution of the battery element 1 according to the present embodiment at that time is conceptually shown in FIG. The left and right vertical and horizontal axes are the same as in FIG. In the battery element 1 of the present embodiment, since the pressure applied to the central part 31 of the battery element 1 is higher than the pressure applied to the outer peripheral part 32, the IV resistance of the central part 31 of the battery element 1 is the outer peripheral part. It becomes lower than the IV resistance of 32 (FIG. 6). As a result, when the above Q = RI ² t is applied and the current density is constant between the central portion and the outer peripheral portion, the in-plane distribution of the calorific value of the battery element 1 is as shown in the curve A2. The amount of heat generated is lower than the amount of heat generated at the outer periphery. That is, the calorific value of the battery element 1 reaches the minimum value QMIN2 at the central portion 31, increases toward the outer peripheral portion 32, and reaches the maximum value QMAX2 at the outer peripheral portion 32.

  At that time, in the outer peripheral portion having high heat dissipation, the heat generation amount is large, but the heat is dissipated and the temperature decreases. In addition, in the central part where heat dissipation is low, the amount of heat generation is small, and even if the heat is not easily dissipated, the temperature is difficult to rise. Therefore, the temperature of the battery element 1 becomes, for example, the lowest temperature TMIN2 at the central portion 31, rises toward the outer peripheral portion 32, and becomes the lowest temperature TMAX2 at the outer peripheral portion 32, as shown by a curve B2. In this case, since the calorific value of the central portion 31 is small, the temperature difference Δ2 = TMAX2−TMIN2 between the central portion 31 and the outer peripheral portion 32 can be made very small compared to the temperature difference Δ1 in the case of FIG. it can. Δ2 is preferably within 2 ° C., more preferably within 1 ° C., further preferably within 0.5 ° C., and even more preferably substantially 0 ° C., that is, the temperature distribution of the battery element 1 is substantially substantially as a whole. It is uniform. Depending on the situation, the temperature at the central portion 31 may be higher than that at the outer peripheral portion 32, but even in this case, the temperature difference Δ2 between the maximum temperature and the minimum temperature is as shown in FIG. The temperature difference Δ1 can be made very small. That is, the temperature distribution of the battery element 1 is substantially uniform as a whole.

  In addition, when the relationship between the pressure (binding force) PMAX2 and PMIN2 of the battery element 1 according to the present embodiment is PCON1≈PMIN2 <PMAX2 with respect to the pressure (binding force) PCON1 of the conventional battery element, the conventional battery The relationship of the resistance values RMAX2 and RMIN2 of the battery element 1 with respect to the resistance value RCON1 of the element is RCON1≈RMAX2> RMIN2. As a result, the relationship between the heat generation amounts QMAX2 and QMIN2 of the battery element 1 with respect to the heat generation amount QCON1 of the conventional battery element is QCON1≈QMAX2> QMIN2. That is, compared with the conventional battery element, the calorific value of the battery element 1 can be reduced as a whole. Further, since the maximum temperature TMAX2 <the maximum temperature TMAX1 can be set, the maximum temperature in the battery element 1 can be lowered. Lowering the maximum temperature can reduce or simplify the cooling mechanism and also reduce the cost, considering the design of the battery system based on the maximum temperature to ensure safety. .

Next, the material of the battery element 1 will be described.
The material which comprises the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13 will not be specifically limited if a desired all-solid-state battery can be formed. Below, the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13 of an all-solid-state lithium secondary battery are demonstrated as a typical example.

(Positive electrode and negative electrode)
The positive electrode 11 includes the positive electrode active material layer 14 and the positive electrode current collector 16 as described above, and further includes a positive electrode lead (not shown) connected to the positive electrode current collector 16. The negative electrode 12 includes the negative electrode active material layer 15 and the negative electrode current collector 17 as described above, and further includes a negative electrode lead (not shown) connected to the negative electrode current collector 17.

(Positive electrode active material layer)
The positive electrode active material layer 14 includes a positive electrode mixture containing a positive electrode active material and a solid electrolyte.
The positive electrode active material is not particularly limited as long as it is an active material that can be used for a Li ion battery, and examples thereof include layered, olivine-based, and spinel type compounds. Specifically, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), lithium nickel manganese cobaltate (LiNi _1-yz Co _y Mn _z O ₂ , such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), lithium nickel cobaltate (LiNi _1-x Co _x O ₂ ), nickel lithium manganate (LiNi _1-x Mn _x O ₂ ), lithium manganate (LiMn) ₂ O ₄ ), a lithium manganate compound (Li _{1 + x} M _y Mn _2−xy O ₄ ; M = Al, Mg, Fe, Cr, Co, Ni, Zn), lithium metal phosphate (LiMPO ₄ , M = Fe, Mn, Co, Ni), lithium metal fluorophosphate (Li ₂ MPO ₄ F, M = Fe, Mn, Co, Ni ), Lithium metal phosphate (Li ₂ MP ₂ O ₇ , M = Fe, Mn, Co, Ni), lithium titanate (Li _x TiO _y ), and the like.

  The positive electrode mixture includes the positive electrode active material described above and a solid electrolyte, preferably a sulfide solid electrolyte, and may further include other components such as a conductive additive and a binder. The solid electrolyte will be described later. Examples of the conductive assistant include VGCF (vapor grown carbon fiber), carbon black, carbon materials such as graphite, and metal materials. Examples of the binder include polytetrafluoroethylene, styrene butadiene rubber, and polyvinylidene fluoride. Although content of a binder changes with kinds of binder, it is the range of 1-10 mass% normally. The proportion of each constituent material in 100% by mass of the positive electrode mixture is preferably in the range of 25 to 90% by mass of the positive electrode active material, in the range of 10 to 75% by mass of the solid electrolyte, and 0 to 10% of the conductive assistant. %, The binder is in the range of 0 to 10% by mass.

(Positive electrode current collector)
The positive electrode current collector 16 has a function of collecting the positive electrode active material layer 14 described above. Examples of the material of the positive electrode current collector 16 include aluminum, SUS, nickel, iron, and titanium. Examples of the shape of the positive electrode current collector 16 include a foil shape, a plate shape, and a mesh shape.

(Negative electrode active material)
The negative electrode active material is not particularly limited as long as it is an active material that can be used for a Li ion battery, and examples thereof include metals and carbon materials. Examples of the metal include metals such as Li, Sn, Si, Al, In, and Sb, alloys that combine some of these, and the like. As the carbon material, a carbon material including a graphite structure (layered structure) at least partially, specifically, natural or artificial graphite, soft carbon, hard carbon, low-temperature calcined carbon, or some of these The material which combined these is illustrated.

  The negative electrode mixture includes a negative electrode active material and a solid electrolyte, preferably a sulfide solid electrolyte, and may further include other components such as a conductive additive and a binder. About a solid electrolyte, a conductive support agent, and a binder, it is the same as that of the case of the above-mentioned positive electrode mixture.

(Negative electrode current collector)
The negative electrode current collector 17 has a function of collecting the negative electrode active material layer 15. As a material for the negative electrode current collector 17, copper can be used in addition to the material for the positive electrode current collector 16. As the shape of the negative electrode current collector 17, the same shape as that of the positive electrode current collector 16 described above can be adopted.

(Solid electrolyte layer)
The solid electrolyte of the solid electrolyte layer 13 is not particularly limited, and examples thereof include inorganic solid electrolytes such as sulfides, oxides, nitrides, and halides. The solid electrolyte may be crystalline, amorphous or glass ceramic. Examples of inorganic solid electrolytes include Li ₂ S—SiS ₂ , LiI—Li ₂ S—SiS ₂ , LiI—Li ₂ S—P ₂ S ₅ , LiI—Li ₂ S—B ₂ S ₃ , Li ₃ PO ₄ —. _{Li 2 S-Si 2 S,} Li 3 PO 4 -Li 2 S-SiS 2, LiPO 4 -Li 2 S-SiS, LiI-Li 2 S-P 2 O 5, LiI-Li 3 PO 4 -P 2 S ₅ , solid sulfide-based amorphous electrolyte powders such as Li ₇ P ₃ S ₁₁ , Li ₃ PS ₄ , and Li ₂ S—P ₂ S ₅ are exemplified. Examples of the inorganic solid electrolyte include solids such as Li ₂ O—B ₂ O ₃ —P ₂ O ₅ , Li ₂ O—SiO ₂ , Li ₂ O—B ₂ O ₃ , Li ₂ O—B ₂ O ₃ —ZnO. An oxide-based amorphous electrolyte powder is exemplified. The inorganic solid _{electrolyte, LiI, LiI-Al 2 O} 3, Li 3 N, Li 3 N-LiI-LiOH, Li 1.3 Al 0.3 Ti 0.7 (PO 4) 3, Li 1 + x + y A x Ti _2-x Si _y P _3-y O ₁₂ (A = Al or Ga, 0 ≦ x ≦ 0.4, 0 <y ≦ 0.6), [(B _1/2 Li _1/2 ) _1-z C _z ] TiO ₃ (B = La, Pr, Nd, Sm, C = Sr or Ba, 0 ≦ x ≦ 0.5), Li ₅ La ₃ Ta ₂ O ₁₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , LiPON Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₃ PO _{(4-3 / 2w)} N _w (w <1), Li _3.6 Si _0.6 P _0.4 O ₄ crystalline oxide powder, Examples thereof include halide powder, nitride powder, and oxynitride powder.

(Other components)
As another component, a separator (not shown) may be used for the all-solid lithium secondary battery. The separator is disposed between the positive electrode current collector 16 and the negative electrode current collector 17 described above. Examples of the material for the separator include polyethylene and polypropylene. The separator may have a single layer structure or a multilayer structure.

  Battery element 1 according to the present embodiment is not necessarily limited to the above-described all solid lithium secondary battery. Any solid battery unit that includes at least a positive electrode, a negative electrode, and a solid electrolyte interposed between the positive electrode and the negative electrode is included in battery element 1 according to the present embodiment.

  The all solid state battery of the present embodiment can suppress the temperature of the central portion of the battery element from excessively rising by making the heat generation amount at the central portion of the battery element larger than the heat generation amount of the outer peripheral portion. . As a result, deterioration at the center of the battery element can be suppressed, and the maximum temperature in the battery element can be reduced.

Examples of the present invention will be described below. The following examples are for illustrative purposes only and are not intended to limit the invention.
The charging / discharging operation and the measurement of the battery voltage at the time of discharging were performed by the following charging / discharging device in the examples.
Battery voltage measuring device during charging: TOSCAT-3200 manufactured by Toyo System

(1) Synthesis of solid electrolyte Li ₂ S (Nippon Chemical Industry Co., Ltd.) 0.7656 g and P ₂ S ₅ (Sigma-Aldrich Co.) 1.2344 g are weighed and mixed in an agate mortar for 5 minutes, and then heptane 4 g was added and mechanically milled for 40 hours using a planetary ball mill to obtain a sulfide solid electrolyte.

(2) Preparation of sulfide solid state battery (battery element) LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (Nichia Corporation) as positive electrode active material 12.03 mg, VGCF (Showa Denko Corporation) ) 0.51 mg and the above-mentioned sulfide solid electrolyte material 5.03 mg were weighed and mixed to obtain a positive electrode mixture.
9.06 mg of graphite (Mitsubishi Chemical Corporation) as a negative electrode active material and 8.24 mg of the above-mentioned sulfide solid electrolyte were weighed and mixed to obtain a negative electrode mixture.
1cm to mold ² was charged with sulfide solid electrolyte 18mg described above, and pressed at 1 ton / cm ² to form a solid electrolyte layer, placed above positive electrode mixture 17.57mg one side thereof, 1 ton / cm ² To form a positive electrode. On the opposite side, 17.3 mg of the negative electrode mixture described above was put and pressed at 4 ton / cm ² to form a negative electrode. Moreover, 15-micrometer-thick Al foil (made by UACJ Co., Ltd.) was used as a positive electrode collector, and 10-micrometer-thick Cu foil (made by UACJ Co., Ltd.) was used as a negative electrode collector.

(3) Battery evaluation The obtained sulfide solid state battery (battery element 1) is sandwiched between two constraining plates, and the constraining plate is interposed in a direction perpendicular to the laminate surface of the laminate including the positive electrode, the solid electrolyte layer, and the negative electrode. A restraining force was applied. Then, when the binding force is changed from 1 MPa to 45 MPa, the sulfide solid state battery is charged to 0.3 V at 0.3 mA and discharged at a current I ₀ of 3 C, and the voltage drop V ₀ after 5 seconds from the start of discharge. Was used to determine the IV resistance R _{0 according} to the formula R ₀ = V ₀ / I ₀ .

(4) Evaluation Results FIG. 8 is a graph showing the relationship between binding force and battery resistance in the examples. The horizontal axis represents restraining force (restraining load), that is, the pressure applied to the central portion of the battery element 1, and the vertical axis represents battery resistance (IV resistance R ₀ ). As shown in FIG. 8, it was found that the battery resistance decreases with increasing binding force. In particular, it was found that when the restraining force is 15 MPa or more, the battery resistance is reduced by about 10% compared to when the restraining force is less than 15 MPa. Here, from the relationship shown in the above Q = RI ² t, if the current (density) is constant, if the IV resistance can be reduced by 10%, the heat generation amount can also be reduced by 10%. Therefore, for example, in the all-solid-state battery A including the restraining member 2 as shown in FIG. 1, the restraining force at the central portion is 15 MPa or more, for example, 15 MPa, and the restraining force at the outer peripheral portion is less than 15 MPa, for example, 1 MPa. Since the battery resistance of the portion is lower by about 10% than the battery resistance of the outer peripheral portion, the calorific value of the central portion can be reduced by about 10% than the calorific value of the outer peripheral portion. As a result, the temperature rise is suppressed to a low level at the center of the battery element 1 having low heat dissipation. In addition, since heat is dissipated at the outer peripheral portion having high heat dissipation and the temperature rise is suppressed, the temperature rise of the entire battery element 1 can be suppressed.

DESCRIPTION OF SYMBOLS 1 Battery element 2 Subsequent member 11 Positive electrode 12 Negative electrode 13 Solid electrolyte layer 14 Positive electrode active material layer 15 Negative electrode active material layer 16 Positive electrode collector 17 Negative electrode collector 21 Connecting rod 22, 23, 24 Constraining plate 24a Plate part 24b Protrusion part 25, 26, 27 Nut 30 Element 31 Center part 31a Center 32 Outer part A All solid state battery L1 Vertical length L2 Horizontal length

Claims (2)

An all-solid battery comprising a battery element comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode,
The amount of heat generated at the center of the battery element during charging and discharging is configured to be smaller than the amount of heat generated at the outer periphery of the battery element.
All solid battery. A restraining member that applies pressure to the laminate from the positive electrode side and the negative electrode side of the battery element in a direction perpendicular to a laminate surface of the laminate including the positive electrode, the solid electrolyte layer, and the negative electrode;
The constraining member is configured such that a pressure applied to the central portion is higher than a pressure applied to the outer peripheral portion,
The all-solid-state battery according to claim 1.

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