JP2014191876A - Electrode for lithium ion secondary battery, lithium ion secondary battery, and apparatus and method for manufacturing electrode for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for a battery having a high capacity, excellent charge and discharge characteristics, and good cycle characteristics, and a technique for manufacturing the same.SOLUTION: The electrode comprises: a collector 11; a first active material structure, including a first active material, that includes a plurality of protrusions 121 protruding from a collector surface at a plurality of points on the collector surface; and a second active material structure, including a second active material having a composition different from that of the first active material and a plurality of protrusions 122 protruding from the collector surface at a plurality of points of the collector surface, which is arranged separately from the first active material on the collector surface. The first active material has a theoretical capacity larger than that of the second active material, and the volume change of the second active material during an insertion and withdrawal reaction of lithium ions is smaller than that of the first active material.

Description

  The present invention relates to a structure of an electrode suitable for a lithium ion secondary battery and a technique for producing an electrode having the structure.

  As a negative electrode active material in a lithium ion secondary battery, a carbon material having a low discharge potential and a relatively large specific capacity has been widely put into practical use. On the other hand, in order to further increase the battery capacity, in recent years, for example, silicon and tin have been attracting attention as active material materials. These materials occlude lithium by an alloying reaction with lithium, and have a considerably larger theoretical capacity than carbon materials. However, these materials have a large volume change in the insertion / extraction reaction of lithium, and there is a problem that the cycle life is short due to the progress of material decay due to repeated charge / discharge, and it is put to practical use as a material for a secondary battery. It has not reached.

  In order to cope with this problem, for example, in the technique described in Patent Document 1, a negative electrode active material layer having a plurality of layers having different porosity and including a polymer binder is formed, and is expanded by the voids formed in the layer. And the volume change at the time of contraction is eased. However, the negative electrode active material layer in this technique has a flat surface, has a small surface area relative to the amount of active material used, and has a large internal porosity, so there is room for improvement in terms of high-speed charge / discharge characteristics.

  On the other hand, the applicants of the present application described the technique described in Patent Document 2 as a method of forming a three-dimensional active material layer having irregularities on the surface in order to increase the surface area of the active material layer and improve the charge / discharge characteristics. Disclosed earlier. In this technology, a nozzle scan method is adopted as a coating method, and a coating liquid containing an active material is discharged from each discharge port while relatively moving a nozzle in which a large number of discharge ports are arranged with respect to a substrate functioning as a current collector. By continuously discharging, the coating liquid is applied to the surface of the substrate in a line shape. Thus, an active material layer having a so-called line-and-space structure in which a large number of linear active material patterns are arranged along the surface of the substrate is formed. In such a structure, a large surface area with respect to the amount of active material used can be obtained, so that an electrode with better charge / discharge characteristics can be formed.

JP 2009-289586 A JP 2011-258367 A

  For example, by using an active material material having a large volume change such as a silicon-based material and creating an active material layer having a line-and-space structure by the technique described in Patent Document 2, the material has high capacity characteristics and a three-dimensional structure. It is expected to achieve both high-speed charge / discharge characteristics. However, according to the knowledge of the inventors of the present application, since insertion / extraction of lithium ions is actively performed in various places due to an increase in surface area, there is still a problem of deterioration of the active material layer due to expansion / contraction. Further, further improvement is required for the cycle characteristics.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a battery electrode having high capacity, excellent charge / discharge characteristics, and good cycle characteristics, and a manufacturing technique thereof.

  In order to achieve the above object, an electrode for a lithium ion secondary battery according to the present invention includes a current collector and a plurality of first active materials and a plurality of protrusions protruding from the current collector surface at a plurality of locations on the current collector surface. A first active material structure having a convex portion and a second active material having a composition different from that of the first active material, and a plurality of convex portions protruding from the current collector surface at a plurality of locations on the current collector surface, respectively The first active material structure is disposed on the current collector surface, and the first active material has a theoretical capacity larger than that of the second active material, and The second active material has a smaller volume change in the lithium ion insertion / release reaction than the first active material.

  In the invention configured as described above, each of the first active material structure and the second active material structure has a plurality of protrusions protruding from the surface of the current collector. Since the surface area can be increased, an electrode having excellent charge / discharge characteristics can be formed. Moreover, high capacity | capacitance is obtained by providing the 1st active material structure containing the 1st active material with a large theoretical capacity | capacitance. Here, since an active material having a large theoretical capacity tends to have a large volume change in the lithium ion insertion / release reaction, an electrode including only the first active material as an active material has cycle characteristics resulting from the collapse of the active material. Deterioration becomes a problem.

  Therefore, in the present invention, the second active material structure is provided side by side with the second active material having a small theoretical capacity but a smaller volume change. Since the second active material, together with the first active material, is responsible for occlusion / release of lithium ions, the expansion / contraction of the first active material is relaxed, and the cycle characteristics are improved. That is, the electrode for a lithium ion secondary battery according to the present invention has high capacity, excellent charge / discharge characteristics, and good cycle characteristics.

  In order to achieve the above object, a battery electrode manufacturing apparatus according to the present invention includes a holding means for holding a base material functioning as a current collector, a first coating liquid containing a first active material, A coating means for individually applying a second coating liquid containing a second active material having a composition different from that of the active material, and coating the base material and the coating means in a predetermined relative movement direction. Relative movement means for moving, and the coating means alternately coats the first coating liquid and the second coating liquid on the substrate in a direction orthogonal to the relative movement direction.

  In the invention configured as described above, by using the first coating liquid containing the first active material as described above and the second coating liquid containing the second active material as described above, It is possible to efficiently produce a lithium ion secondary battery electrode having characteristics.

  In this battery electrode manufacturing apparatus, the coating means includes, for example, a plurality of first discharge ports capable of continuously sending the first coating liquid and a plurality of second discharge ports capable of continuously sending the second coating liquid. May be configured to include nozzle bodies alternately arranged in a direction orthogonal to the relative movement direction. In such a configuration, the structure body made of the first active material and the structure body made of the second active material can be formed using a single nozzle body.

  Further, for example, the coating means includes a first nozzle body in which a plurality of first discharge ports capable of continuously delivering the first coating liquid are arranged in a direction orthogonal to the relative movement direction, and the first nozzle body in the relative movement direction. And a plurality of second discharge ports arranged continuously in a direction perpendicular to the relative movement direction, and orthogonal to the relative movement direction. The positions of the plurality of first discharge ports and the positions of the plurality of second discharge ports in the direction may be different from each other. In such a configuration, each of the first and second nozzle bodies only needs to have a configuration capable of discharging a single coating liquid, and a known configuration can be applied as such a configuration.

  Further, for example, in these electrode manufacturing apparatuses, for example, a pair of roller members that hold a long sheet-like base material wound in a roll shape and wind up the base material drawn from the roll at a constant speed are provided. The roller member may have a function as a holding unit and a relative moving unit. In such a configuration, the first active material structure and the second active material structure described above are continuously formed on a long sheet-like base material, so that the lithium ion secondary battery having the above excellent characteristics can be obtained. It is possible to efficiently produce secondary battery electrodes.

  In addition, in order to achieve the above object, the battery electrode manufacturing method according to the present invention applies a first coating liquid containing a first active material to the surface of a base material that functions as a current collector. A step of forming a first active material structure having a plurality of convex portions projecting from the current collector surface at a plurality of locations on the surface, and a volume change and a theoretical capacity in a lithium ion insertion / desorption reaction on the surface of the substrate; A second active material having a plurality of protrusions that protrude from the current collector surface at a plurality of locations on the current collector surface by applying a second coating liquid containing a second active material smaller than the first active material Forming a structure, and forming the first active material structure and the second active material structure separately from each other on the current collector surface.

  In the invention configured as described above, it is possible to efficiently manufacture an electrode for a lithium ion secondary battery having excellent characteristics as described above. In addition, any of the process of forming a 1st active material structure and the process of forming a 2nd active material structure may be performed previously, and may be performed simultaneously.

  In each of the above-described inventions, for example, each of the protrusions of the first active material structure is formed in a line extending in a predetermined extending direction along the current collector surface, while the second active material Each of the convex portions of the structure is formed in a line extending in the extending direction, and in the direction orthogonal to the extending direction, the convex portion of the first active material structure and the convex portion of the second active material structure And may be arranged alternately.

  In such a configuration, the convex portions of the first active material structures each formed in a line shape expand in a direction orthogonal to the line extending direction, that is, a direction of expanding the line cross section, and around each convex portion. Since there is a space for absorbing the volume change, the collapse of the first active material structure is suppressed. And since the convex part of a 2nd active material structure is provided adjacent to the convex part of a 1st active material structure, occlusion of lithium ion can be shared effectively. These characteristics further improve the cycle characteristics.

  For example, the cross-sectional area of the convex part of the 2nd active material structure in the cross section orthogonal to the extending direction may be larger than the cross-sectional area of the convex part of the 1st active material structure in the extending direction. . Since the second active material has a smaller theoretical capacity than the first active material, the capacity as an electrode is smaller than that of an electrode having the same structure constituted only by the first active material. By increasing the cross-sectional area of the convex portion of the second active material structure, it is possible to compensate for the low theoretical capacity and suppress the decrease in electrode capacity.

In this case, for example, the theoretical capacity per unit volume of the first active material is Q1, the width of the convex portion of the first active material structure that contacts the current collector surface, and the height from the current collector surface Is W1 and H1, respectively, the theoretical capacity per unit volume of the second active material is Q2, the width of the portion of the convex portion of the second active material structure that contacts the current collector surface and the current from the current collector surface When the height is W2 and H2, respectively, the following relational expression:
W1 / H1 ≦ W2 / H2 (Q2 / Q1)
A configuration in which the above relationship is established may be adopted. Although details will be described later, in such a configuration, a capacity equivalent to that of an electrode using only the first active material as an active material can be obtained, and the cycle characteristics are further improved.

  For example, the first active material may include a material that occludes lithium by an alloying reaction with lithium. An active material of a type that occludes lithium in such a form generally has a high capacity but a large volume change. Therefore, when the present invention is applied to an electrode using such a material, the above-described effects are particularly remarkable. More specifically, a material containing silicon or a silicon compound can be suitably used as the first active material.

  On the other hand, as the second active material, for example, carbon or a metal oxide can be included. These active material materials are of a type that occludes lithium in the crystal lattice, and the capacity cannot be increased, but the volume change is small. Therefore, it is particularly suitable as the second active material of the present invention.

  In order to achieve the above object, a lithium ion secondary battery according to the present invention has a negative electrode having the same configuration as any of the above-described lithium ion secondary battery electrodes, an electrolyte layer, a positive electrode active material layer, It has a structure in which a positive electrode formed by laminating a positive electrode current collector is laminated in order. In the invention configured as described above, by providing the negative electrode having both high capacity, high-speed charge / discharge characteristics and excellent cycle characteristics as described above, a lithium ion secondary battery having good characteristics can be configured. Is possible.

  According to the present invention, the first active material structure having the first active material having a large theoretical capacity, and the second active material having a smaller capacity than the first active material structure but having a small volume change in the lithium insertion / elimination reaction can be obtained. By mixing the two active material structures on the surface of the current collector, it is possible to provide a battery electrode having high capacity, excellent charge / discharge characteristics, and good cycle characteristics.

It is a figure which shows the structural example of the battery manufactured using this invention. It is a figure which shows the dimension of a line required in order to avoid the reduction | decrease in capacity | capacitance. It is a schematic diagram which shows two embodiment of the electrode manufacturing apparatus concerning this invention. It is a figure which shows the structure of the coating nozzle in the electrode manufacturing apparatus of 1st Embodiment. It is a figure which shows the structure of the coating nozzle in the electrode manufacturing apparatus of 2nd Embodiment.

  FIG. 1 is a diagram showing a configuration example of a battery manufactured using the present invention. More specifically, FIG. 1A is a schematic diagram showing a cross-sectional structure of a lithium ion secondary battery module that employs an embodiment of an electrode for a lithium ion secondary battery according to the present invention as a negative electrode, and FIG. b) is a perspective view showing the negative electrode. In this lithium ion secondary battery module 1, a negative electrode active material layer 12, an electrolyte layer 13, a positive electrode electrode 15 including a positive electrode active material layer 16 and a positive electrode current collector 17 are sequentially arranged on a negative electrode current collector 11. It has a laminated structure.

  FIG. 1B shows the structure of a negative electrode 10 formed by forming a negative electrode active material layer 12 on the surface of the negative electrode current collector 11. As shown in FIG. 1B, the negative electrode active material layer 12 has linear patterns 121 and 122 extending along a direction perpendicular to the paper surface of FIG. A line-and-space structure with a large number of lines. More specifically, the negative electrode active material layer 12 has a structure in which the relatively narrow first lines 121 and the wider second lines 122 are alternately arranged on the surface of the negative electrode current collector 11. In this example, the height of the first line 121 and the second line 122 from the surface of the current collector 11 is the same, but is not limited thereto.

  The negative electrode active material layer 12 having the above structure faces the positive electrode active material layer 16 with the electrolyte layer 13 interposed therebetween. The positive electrode active material layer 16 is a thin film having a substantially uniform thickness formed on the surface of the positive electrode current collector 17 by a positive electrode active material. The electrolyte layer 13 may be either a solid electrolyte filled in a gap space between the positive electrode 15 and the negative electrode 10 or a separator and an electrolytic solution. The lithium ion secondary battery module 1 thus formed is provided with a tab electrode as appropriate, or a plurality of modules are stacked and accommodated in a package to constitute the lithium ion secondary battery B.

Here, as the material constituting each layer of the lithium ion secondary battery module 1, for example, an aluminum foil or a copper foil can be used as the positive electrode current collector 17 and the negative electrode current collector 11, respectively. Further, as the active material constituting the positive electrode active material layer 16, a known material as the positive electrode active material, for example, a material mainly composed of LiCoO ₂ (LCO), LiNiO ₂ or LiFePO ₄ , LiMnPO ₄ , LiMn ₂ O ₄ , A compound typically represented by LiMeO ₂ (Me = MxMyMz; Me, M is a transition metal, x + y + z = 1), such as LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ etc. can be used.

The separator constituting the electrolyte layer 13 is, for example, a polypropylene (PP) sheet, and the electrolytic solution is, for example, a lithium salt as a supporting salt, such as ethylene carbonate and diethyl carbonate containing lithium hexafluorophosphate (LiPF ₆ ). (EC / DEC) can be used. When the electrolyte layer 13 is composed of a solid electrolyte, for example, a copolymer of polyethylene oxide and polystyrene can be used. The material of each functional layer is not limited to these.

  On the other hand, the negative electrode active material layer 12 is composed of two kinds of active material materials. More specifically, the first line 121 and the second line 122 constituting the negative electrode active material layer 12 have active material materials having different compositions. Among these, the narrow first line 121 includes an active material having a relatively large theoretical capacity (hereinafter referred to as “first active material”). As a negative electrode active material having a large theoretical capacity, a material that occludes lithium by an alloying reaction with lithium is known. Typically, for example, silicon (Si) and its compound (for example, SiO), tin (Sn) and its compound (for example, SnO), and the like. Other than these, metals (metals) or metalloids that form alloys with lithium metal include magnesium (Mg), calcium (Ca), aluminum (Al), germanium (Ge), lead (Pb), arsenic (As), and antimony (Sb). )and so on. In the following, single crystal silicon fine particles will be taken as an example.

The second line 122 wider than the first line 121 has an active material (hereinafter referred to as “second material”) that has a smaller theoretical capacity than the active material constituting the first line 121 but has a smaller volume change during lithium insertion and desorption. "Active material"). Ideally, there should be almost no volume change. As a material having a small volume change in the lithium insertion / extraction reaction, a material that occludes lithium between crystal lattices is known. For example, a carbon-based material such as graphite or a metal oxide-based active material is representative. It is. Examples of the metal oxide include Li ₄ Ti ₅ O ₁₂ (LTO), Nb ₂ O ₅ , TiO ₂ , WO ₂ , MoO ₂ , and Fe ₂ O ₃ . In the following, graphite is taken as an example.

  The active material having a large theoretical capacity such as silicon constituting the first line 121 generally has a large volume change in the lithium insertion / extraction reaction. When such a material is used as the negative electrode active material, there is a problem in that the cycle life is short because the active material layer collapses due to expansion / contraction associated with charge / discharge. In particular, when the surface area is increased with a three-dimensional structure of the active material layer as in the line-and-space structure of the present embodiment, the charge / discharge characteristics are improved as the surface area is increased, and the expansion is caused by the gap between the lines. Can be absorbed. However, since the insertion / extraction of lithium ions into / from the active material layer becomes active at various locations on the surface, the expansion / contraction becomes intense, and thus it is still necessary to improve the cycle characteristics.

  Therefore, in this embodiment, for example, the first line 121 composed of the first active material having a large theoretical capacity such as silicon but a large volume change, and a small theoretical capacity such as graphite but a small volume change are present. By forming the second line 122 composed of the second active material on the negative electrode current collector 11, the cycle characteristics can be improved while ensuring high capacity and high-speed charge / discharge characteristics. Yes.

  The negative electrode 10 of this embodiment includes a plurality of first lines 121 extending in a predetermined direction by a first active material having a large theoretical capacity. By forming the active material layer in a plurality of lines separated from each other, expansion due to lithium insertion mainly occurs in a direction orthogonal to the extending direction of the line, that is, in a direction of expanding the cross section of the line. In this way, the expansion direction of the line is regulated, and a space capable of absorbing the expansion is provided around each line, so that the active material layer is compared with a case where expansion in a random direction is allowed. It is hard to collapse.

  Moreover, the volume change of the 1st line 121 is carried out by making the part of the line which comprises the active material layer 12 the 2nd line 122 comprised by the 2nd active material with a smaller volume change bears the effect | action which occludes lithium. Is more relaxed. In particular, when the second line 122 is disposed adjacent to the first line 121, that is, when the first line 121 and the second line 122 are alternately arranged, the occlusion of lithium ions is performed between the first line 121 and the second line 122. Can be distributed and carried effectively.

  In addition, since the second line 122 is less expanded, most of the gap between the first line 121 and the second line 122 can be used for absorbing the expansion of the first line 121. In addition, it is possible to reduce the gap between the lines and increase the line density as compared with the case where the adjacent lines expand together. In addition, by disposing the first line 121 and the second line 122 apart from each other, the first line 121 is allowed to expand and the second line 122 is expanded from the side by the expanded first line 121. It can be prevented from collapsing under pressure.

  Thus, the electrode which has a favorable cycling characteristic can be comprised with high capacity | capacitance and the outstanding charging / discharging characteristic by making the negative electrode active material layer 12 into the said structure. The improvement of the cycle characteristics is due to the effect of suppressing the collapse of the first line 121 itself by the above-described three-dimensional structure and the effect of the second line 122 having a small volume change slowing the progress of the capacity decrease as the whole electrode. is there. However, since the second line 122 includes an active material having a small theoretical capacity, simply replacing a part of the line made of a material having a large theoretical capacity reduces the capacity of the entire electrode. Next, the design of the line dimension for avoiding this will be described.

  FIG. 2 is a diagram showing the dimensions of a line necessary for avoiding a decrease in capacity. In the figure, a dotted line schematically shows a state in which the first line 121 is expanded by insertion of lithium. First, as shown in FIG. 2A, a case is considered in which all of the lines constituting the active material layer are the first lines 121 formed of an active material having a high theoretical capacity. Each first line 121 is assumed to have the same cross-sectional shape, and the line width at the portion in contact with the current collector 11 is denoted by reference sign W1 and the height from the surface of the current collector 11 is denoted by reference sign H1.

When the theoretical capacity per unit volume of the first active material is Q1, the capacity C1 of the first line 121 per unit length in the direction perpendicular to the paper surface is given by the following formula:
C1 = W1, H1, Q1 (Formula 1)
Can be represented by

On the other hand, as shown in FIG. 2B, a case is considered in which half of the lines constituting the active material layer is replaced with a second line 122 having a lower theoretical capacity. The line width at the portion of the second line 122 in contact with the current collector 11 is represented by a symbol W2, and the height from the surface of the current collector 11 is represented by a symbol H2. When the theoretical capacity per unit volume of the second active material constituting the second line 122 is Q2 (<Q1), the capacity C2 of the second line 122 per unit length in the direction perpendicular to the paper surface is given by :
C2 = W2, H2, Q2 (Formula 2)
Can be represented by In order to avoid a decrease in capacity due to replacement, the capacity C2 expressed by (Expression 2) needs to be equal to or greater than the capacity C1 expressed by (Expression 1). From these conditions:
W1 / H1 ≦ W2 / H2 (Q2 / Q1) (Formula 3)
Is obtained. In addition, in order to secure a gap between the first line 121 and the second line 122, the following formula is established between each line width and the line pitch P:
W2 <(2P-W1) (Formula 4)
The relationship needs to be satisfied. In addition, when it thinks that the width | variety of the 1st line 121 expands to the maximum n times with lithium occlusion, the conditions for the 1st line 121 and the 2nd line 122 not contacting in the state expanded to the maximum, The following formula:
W2 <(2P-n · W1) (Formula 5)
It is represented by

  As described above, when the first line 121 and the second line 122 have the same height, the width W2 of the second line 122 including the second active material having a small theoretical capacity is made larger than the width W1 of the first line 121. There is a need. In principle, it is sufficient if the cross-sectional area of the line is adjusted according to the size of the theoretical capacity, as indicated by the above (Equation 3). Then, the surface area of the second line 122 in contact with the electrolyte layer 13 is increased, so that lithium ions in the electrolyte layer 13 can be efficiently stored, and the amount of lithium ions that the first line 121 should store is reduced. The expansion can be mitigated.

  Next, a technique for manufacturing the negative electrode 10 having the above structure will be described. As a technique for forming an active material layer having such a line-and-space structure, for example, as previously disclosed in the above-mentioned Patent Document 2 (Japanese Patent Laid-Open No. 2011-258367) by the applicant of the present application, so-called nozzle scanning is performed. It is possible to apply a coating technique of the method.

  FIG. 3 is a schematic view showing two embodiments of the electrode manufacturing apparatus according to the present invention. More specifically, FIG. 3 (a) is a diagram showing a main configuration of the first embodiment of the electrode manufacturing apparatus according to the present invention, and FIG. 3 (b) is a diagram of the second embodiment of the electrode manufacturing apparatus according to the present invention. It is a figure which shows main structures.

  The electrode manufacturing apparatus 100 according to the first embodiment uses a metal sheet S functioning as the negative electrode current collector 11 in a completed electrode and battery as a base material, and applies an active material to the surface to form an active material layer. It is an apparatus for manufacturing the battery electrode 10 in which the current collector and the active material are laminated by forming. The sheet S may be a single metal foil or a thin plate, but for example, a sheet made of a resin sheet bonded to a resin sheet or a sheet obtained by chemically depositing a metal may be suitably used.

  For the following explanation, XYZ coordinate axes are set as shown in FIG. Here, the XY plane is a horizontal plane, and the Z axis coincides with the vertical axis. The positive direction on the Z-axis is a vertically upward direction.

  The electrode manufacturing apparatus 100 holds the sheet S before forming the active material wound in a roll shape and feeds the sheet S after the active material layer is formed, and the supply roller 101 that feeds the sheet S at a constant speed. A winding roller 102. The sheet S is stretched around these rollers and is conveyed at a constant speed in the arrow direction Dt as the rollers rotate. In the example of FIG. 3, the supply roller 101 and the take-up roller 102 each have a rotation axis parallel to the X axis, and the sheet S is conveyed in a direction parallel to the Y axis as the rollers 101 and 102 rotate. Is done. That is, in this example, the transport direction Dt of the sheet S is the Y direction.

  The electrode manufacturing apparatus 100 is provided with a control unit 110 that controls the operation of each part of the apparatus, and the rollers 101 and 102 rotate in accordance with a control command from a conveyance control unit 114 provided in the control unit 110 to rotate the sheet. Transport S.

  Along the conveyance path of the sheet S conveyed in the conveyance direction Dt, the first application nozzle 150, the second application nozzle 160, and the drying heater 170 are sequentially opposed to the upper surface of the sheet S from the upstream side. Has been placed. Accordingly, when focusing on one point on the surface of the sheet S, the point is fed from the supply roller 101 and is opposed to the first coating nozzle 150, opposed to the second coating nozzle 160, and opposed to the drying heater 170. Will be passed in order. Backup rollers 103 and 104 are provided at positions corresponding to the first application nozzle 150 and the second application nozzle 160 on the lower surface side of the sheet S, respectively.

  The first coating nozzle 150 receives the supply of the paste-like first coating liquid containing the first active material fed from the first coating liquid supply unit 111 provided in the control unit 110, and removes the coating liquid on the lower surface. It is discharged from the discharge port and applied to the surface of the sheet S. The first coating liquid supply unit 111 includes a storage unit that stores the first coating liquid, and a liquid feeding unit such as a mono pump that controls and stops the feeding of the first coating liquid to the first coating nozzle 150. Thereby, the first application nozzle 150 can continuously discharge the first application liquid at a constant flow rate.

  The second coating nozzle 160 receives the supply of the paste-like second coating liquid containing the second active material fed from the second coating liquid supply unit 112 provided in the control unit 110, and transfers the coating liquid to the sheet. Apply to S surface. Similarly to the first coating liquid supply unit, the second coating liquid supply unit 112 stores a second coating liquid, and pumps and stops the second coating liquid to the second coating nozzle 160, for example, a MONO pump. And a liquid feeding part. Accordingly, the second application nozzle 160 can continuously discharge the second application liquid at a constant flow rate.

  The drying heater 170 is controlled to a predetermined temperature by a heater control unit 113 provided in the control unit 20. The drying heater 170 heats the coating liquid applied to the surface of the sheet S from the first coating nozzle 150 and the second coating nozzle 160 to accelerate the drying and solidification thereof. The dried sheet S is again wound up into a roll by the winding roller 102.

  On the other hand, the electrode manufacturing apparatus 200 of the second embodiment shown in FIG. 3B is different from that of the first embodiment described above in the structure of the coating nozzle and the arrangement of the backup roller associated therewith. Except for these points, the configuration of each part is the same as that of the first embodiment. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As will be described later, the coating nozzle 250 of this embodiment has two types of discharge ports that are independent of each other in a single casing, and the first coating liquid and the second coating solution are respectively supplied from these two types of discharge ports. It is possible to discharge. Accordingly, only one application nozzle 250 is provided, and accordingly, only one backup roller 203 is provided. The first coating liquid from the first coating liquid supply unit 111 and the second coating liquid from the second coating liquid supply unit 112 are both supplied to the coating nozzle 250.

  In these two embodiments, as the first coating liquid and the second coating liquid containing the active material, in addition to the first active material or the second active material described above, acetylene black or kettle as a conductive auxiliary agent, respectively. Chain black, polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) or polytetrafluoroethylene (PTFE) as binder, N-methyl-2 as solvent -What mixed pyrrolidone (NMP) etc. can be used. In addition, about the 1st coating liquid containing the silicon | silicone or its compound as a 1st active material, a polyamideimide can be used suitably as a binder.

  By changing the composition ratio of the coating liquid obtained by mixing such materials, the viscosity can be adjusted appropriately. As the coating liquid for continuously forming from the coating nozzle to form the structure as in the present embodiment, a paste-like liquid having a viscosity of 500 Pa · s to 10000 Pa · s is suitable, for example.

  FIG. 4 is a view showing the structure of the coating nozzle in the electrode manufacturing apparatus of the first embodiment. More specifically, FIG. 4A is a side view showing the internal structure of the first application nozzle 150, and FIG. 4B is a view showing the structure of the lower surface of each of the first application nozzle 150 and the second application nozzle 160. It is. FIG. 4C is a view showing a state of application by the first application nozzle 150 and the second application nozzle 160.

  As shown in FIG. 4A, the first application nozzle 150 has a manifold space 151 in which the first application liquid can be temporarily stored, and a plurality of lower surfaces 152 are provided on the lower surface 152 as shown in FIG. The discharge port 153 is provided. Each discharge port 153 has the same opening shape corresponding to the cross-sectional shape of the first line 121, and is arranged on the lower surface 152 of the first application nozzle 150 at regular intervals in the X direction. The first coating liquid fed from the first coating liquid supply unit 111 is supplied to the manifold space 151, and each discharge port 153 communicates with the manifold space 151. Therefore, when the first coating liquid is pumped from the first coating liquid supply unit 111 to the first coating nozzle 150, the first coating liquid is discharged from each discharge port 153 via the manifold space 151.

  The internal structure of the second application nozzle 160 is basically the same as that of the first application nozzle 150, but the shape and arrangement of the discharge ports are different. That is, as shown in FIG. 4B, the opening dimension in the X direction is lower on the lower surface 162 of the second application nozzle 160 than the discharge port 153 of the first application nozzle 150 corresponding to the cross-sectional shape of the second line 122. The large discharge ports 163 are arranged at equal intervals in the X direction. However, the position in the X direction of each discharge port 163 is shifted by half the arrangement pitch of the discharge ports 153 of the first application nozzle 150.

  FIG. 4C shows that the first application liquid and the second application liquid are continuously discharged from the discharge ports 153 and 163 provided in the first application nozzle 150 and the second application nozzle 160, respectively, at a constant flow rate. As described above, the active material layer 12 in which the first lines 121 formed by the first coating liquid and the second lines 122 formed by the second coating liquid are arranged in parallel and alternately in the X direction is the sheet S. Formed on top. The sheet S on which the active material layer 12 is formed is finally cut into an appropriate size and functions as the negative electrode current collector 11.

  FIG. 5 is a view showing the structure of the coating nozzle in the electrode manufacturing apparatus of the second embodiment. More specifically, FIG. 5A is a side view showing the internal structure of the application nozzle 250, and FIG. 5B is a view showing the structure of the lower surface of the application nozzle 250. FIG. 5C is a view showing a state of application by the application nozzle 250.

  As shown in FIG. 5A, the application nozzle 250 according to the second embodiment has two independent manifold spaces 251 and 252 inside. Among these, the first coating liquid from the first coating liquid supply unit 111 is supplied to the first manifold space 251, while the second coating liquid from the second coating liquid supply unit 112 is supplied to the second manifold space 252. Is supplied. The first manifold space 251 communicates with a first discharge port 254 formed in the nozzle lower surface 253, and the second manifold space 252 communicates with a second discharge port 255 formed in the nozzle lower surface 253.

  As shown in FIG. 5B, the first discharge port 254 and the second discharge port 255 are arranged in a row in the X direction on the lower surface 253 of the nozzle, and the first discharge port 254 and the second discharge port 255 are arranged. They are arranged alternately at equal intervals in the X direction.

  By continuously discharging the first coating liquid from the first discharge port 254 and the second coating liquid from the second discharge port 255 at a constant flow rate, as shown in FIG. The active material layer 12 in which the first lines 121 formed by the above and the second lines 122 formed by the second coating liquid are alternately arranged in parallel and in the X direction is formed on the sheet S.

  Thus, it is possible to manufacture the negative electrode 10 having the structure shown in FIG. 1B by using either the electrode manufacturing apparatus 100 of the first embodiment or the electrode manufacturing apparatus 200 of the second embodiment. . That is, these electrode manufacturing apparatuses 100 and 200 can manufacture a negative electrode having high capacity, excellent charge / discharge characteristics, and good cycle characteristics.

  Among these, in the first embodiment, since the arrangement pitch of the discharge ports is large in each of the first application nozzle 150 and the second application nozzle 160, the periphery of the discharge ports can be formed relatively thick. For this reason, sufficient intensity | strength can be ensured to discharge the pressurized highly viscous coating liquid. However, the relative mounting position accuracy of the first coating nozzle 150 and the second coating nozzle 160 in the electrode manufacturing apparatus 100 affects the accuracy of the line arrangement. On the other hand, the coating nozzle 250 of the second embodiment does not have a problem of positional accuracy, but the thickness is thin because the arrangement pitch of the discharge ports is small. It is desirable to use these as needed.

  As described above, in this embodiment, the negative electrode current collector 11 corresponds to the “base material” and “current collector” of the present invention. Further, the plurality of first lines 121 as a whole correspond to the “first active material structure” of the present invention, and each first line 121 corresponds to the “projection of the first active material structure”. On the other hand, the plurality of second lines 122 as a whole corresponds to the “second active material structure” of the present invention, and each second line 122 corresponds to “a convex portion of the second active material structure”.

  In the electrode manufacturing apparatuses 100 and 200 described above, the supply roller 101 and the take-up roller 102 function as “a pair of roller members” of the present invention. It has the function of “moving means”. In addition, the first application nozzle 150 and the second application nozzle 160 in the first embodiment function as the “first nozzle body” and the “second nozzle body” of the present invention, respectively. Further, the application nozzle 250 in the second embodiment functions as a “nozzle body” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the electrode manufacturing apparatus 100 according to the first embodiment described above, after the first coating liquid containing the first active material is applied to the substrate S, the second coating liquid containing the second active material is applied. However, this order may be reversed.

  Further, for example, in the electrode manufacturing apparatus 100 or the like of the above-described embodiment, a so-called roll-to-roll coating is performed by applying a coating liquid containing an active material to the base material S of a long sheet wound in a roll shape and winding it again. The electrodes are continuously manufactured by a roll manufacturing method. However, the present invention is not limited to this, and can be applied to, for example, a single-wafer manufacturing apparatus and a manufacturing method for applying a coating liquid to an independent single-wafer substrate. In this case, the substrate may be fixed and the application nozzle may be moved.

  Moreover, the cross-sectional shape of the active material pattern in the said embodiment shows the example, Comprising: It is not limited to this, It is possible to use arbitrary cross-sectional shapes. Moreover, the opening shape of the discharge port provided in the nozzle body is not limited to the rectangular shape as in the above embodiment, and various types can be used.

  According to the present invention, it is possible to provide a negative electrode for a lithium ion secondary battery having high capacity, excellent charge / discharge characteristics, and good cycle characteristics, and the performance of a lithium ion secondary battery using the same. It is possible to improve.

1 Lithium ion secondary battery module 10 Negative electrode 11 Negative electrode current collector (base material, current collector)
100, 200 Electrode manufacturing apparatus 101 Supply roller (roller member, holding means, relative moving means)
102 Winding roller (roller member, holding means, relative moving means)
121 1st line (1st active material structure, convex part)
122 2nd line 122 (2nd active material structure, convex part)
150 First application nozzle (first nozzle body)
160 Second application nozzle (second nozzle body)
250 Application nozzle (nozzle body)
B Lithium ion secondary battery

Claims (15)

A current collector,
A first active material structure including a first active material and having a plurality of protrusions protruding from the current collector surface at a plurality of locations on the current collector surface;
A second active material having a composition different from that of the first active material, and having a plurality of convex portions respectively projecting from the current collector surface at a plurality of locations on the current collector surface; A second active material structure spaced apart from the first active material structure,
The first active material has a theoretical capacity larger than that of the second active material, and the second active material has lithium ions whose volume change in the lithium ion insertion / desorption reaction is smaller than that of the first active material. Secondary battery electrode.   Each of the convex portions of the first active material structure is formed in a line extending in a predetermined extending direction along the surface of the current collector, while the convex of the second active material structure is formed. Each of the portions is formed in a line extending in the extending direction, and in the direction perpendicular to the extending direction, the convex portion of the first active material structure and the second active material structure The electrode for a lithium ion secondary battery according to claim 1, wherein the convex portions are alternately arranged.   The cross-sectional area of the said convex part of the said 2nd active material structure in the cross section orthogonal to the said extending direction is larger than the cross-sectional area of the said convex part of the said 1st active material structure in the said extending direction. Or the electrode for lithium ion secondary batteries of 2. The theoretical capacity per unit volume of the first active material is Q1, the width of the portion of the first active material structure that contacts the current collector surface, and the height from the current collector surface. Are W1 and H1, respectively, Q2 is the theoretical capacity per unit volume of the second active material, and the width of the portion of the convex portion of the second active material structure that contacts the current collector surface and the current collector When the height from the electrical surface is W2 and H2, respectively, the following relational expression:
W1 / H1 ≦ W2 / H2 (Q2 / Q1)
The electrode for a lithium ion secondary battery according to claim 1, wherein:   The electrode for a lithium ion secondary battery according to any one of claims 1 to 4, wherein the first active material includes a material that occludes lithium by an alloying reaction with lithium.   The electrode for a lithium ion secondary battery according to claim 1, wherein the first active material contains silicon or a silicon compound.   The electrode for a lithium ion secondary battery according to claim 1, wherein the second active material contains carbon or a metal oxide.   A negative electrode having the same configuration as the electrode for a lithium ion secondary battery according to any one of claims 1 to 7, an electrolyte layer, and a positive electrode formed by laminating a positive electrode active material layer and a positive electrode current collector in order. Lithium ion secondary battery having a structure laminated on. Holding means for holding a base material that functions as a current collector;
Application in which a first coating liquid containing a first active material and a second coating liquid containing a second active material having a composition different from that of the first active material are individually ejected and applied to the substrate. Means,
A relative movement means for relatively moving the base material and the coating means in a predetermined relative movement direction;
The battery electrode manufacturing apparatus for applying the first coating liquid and the second coating liquid to the base material alternately in the direction orthogonal to the relative movement direction.   The first active material has a larger theoretical capacity than the second active material, and the second active material has a smaller volume change in a lithium ion insertion / desorption reaction than the first active material. The battery electrode manufacturing apparatus according to 9.   In the coating unit, a plurality of first discharge ports capable of continuously feeding the first coating liquid and a plurality of second discharge ports capable of continuously feeding the second coating liquid are orthogonal to the relative movement direction. The apparatus for manufacturing a battery electrode according to claim 9 or 10, comprising nozzle bodies arranged alternately in a direction in which the battery electrode is arranged.   The coating means includes a first nozzle body in which a plurality of first discharge ports capable of continuously delivering the first coating liquid are arranged in a direction orthogonal to the relative movement direction, and the first nozzle body in the relative movement direction. A plurality of second discharge ports arranged at positions different from the nozzle body and capable of continuously delivering the second coating liquid are arranged in a direction perpendicular to the relative movement direction, and the relative The battery electrode manufacturing apparatus according to claim 9 or 10, wherein positions of the plurality of first discharge ports and positions of the plurality of second discharge ports in a direction orthogonal to a moving direction are different from each other.   A long sheet-like base material wound in a roll shape is held, and a pair of roller members for winding the base material drawn from the roll at a constant speed are provided. The battery electrode manufacturing apparatus according to any one of claims 9 to 12, which has a function as a relative movement means. Applying a first coating liquid containing a first active material to the surface of a base material functioning as a current collector, a plurality of protrusions projecting from the current collector surface respectively at a plurality of locations on the current collector surface Forming a first active material structure having:
A surface of the current collector is coated with a second coating liquid containing a second active material whose volume change and theoretical capacity in the lithium ion insertion / desorption reaction is smaller than that of the first active material. Forming a second active material structure having a plurality of convex portions projecting from the surface of the current collector at a plurality of locations of the first active material structure and the second active material structure, The battery electrode manufacturing method which forms mutually spaced apart on the said collector surface.   Each of the convex portions of the first active material structure is formed in a line shape extending in a predetermined extending direction along the surface of the current collector, while each of the convex portions of the second active material structure is formed. Formed in a line extending in the extending direction, and alternately arranging the convex portions of the first active material structure and the convex portions of the second active material structure in a direction perpendicular to the extending direction. The battery electrode manufacturing method according to claim 14.

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