JP2012174959A - Power storage cell and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem of a power storage cell pre-doped with lithium ions that enhancement of workability and shortening of the pre-dope time are required when forming an active material layer.SOLUTION: Each positive electrode plate of a power storage cell includes a positive electrode collector, and a positive electrode active material layer formed on both surfaces of the positive electrode collector. A first cut is formed from the edge toward the inside of the positive electrode plate. The positive electrode active material layer can carry lithium ions or anions reversibly. Each negative electrode plate includes a negative electrode collector, and a negative electrode active material layer formed on both surfaces of the negative electrode collector. A second cut is formed from the edge toward the inside of the negative electrode plate. The negative electrode active material layer contains a material which can occlude and release lithium ions, and is occluding lithium ions.

Description

  The present invention relates to a storage cell that has been pre-doped with lithium ions, and a method for manufacturing a storage cell that has been pre-doped with lithium.

  2. Description of the Related Art Lithium ion capacitors and lithium ion secondary batteries are attracting attention as power storage devices for storing regenerative power in hybrid work machines and the like. Generally, a carbon-based material capable of inserting and extracting lithium ions is used for the negative electrode of the lithium ion capacitor. A large voltage can be obtained by pre-doping lithium ion in the negative electrode. As the positive electrode, the same one as the positive electrode of the electric double layer capacitor is used. The negative electrode and the positive electrode are alternately stacked with a separator interposed therebetween.

  A technique for forming a positive electrode and a negative electrode by forming a slurry containing an active material on both sides of a mesh current collector is known. The negative electrode can be pre-doped with lithium ions by bringing lithium metal into contact with the laminate of the positive electrode, the negative electrode, and the separator and leaving it in the electrolytic solution. Lithium ions are transported in the thickness direction through the voids of the mesh current collector.

  There has been proposed a method in which a part of a negative electrode active material layer applied to a negative electrode current collector is peeled off and metallic lithium is attached to the part, thereby pre-doping lithium ions into the negative electrode active material. In this method, lithium ions are transported in the in-plane direction within the negative electrode active material layer.

JP 2009-187753 A

  In the method of applying a slurry containing an active material to a mesh-like current collector, the slurry passes through the mesh voids. Since the slurry that has passed through the voids of the mesh needs to be held in the mesh, the coating method is restricted. In the method of transporting lithium ions in the in-plane direction, since the distance to be transported becomes long, it is difficult to shorten the pre-doping time.

According to one aspect of the invention,
A positive electrode plate and a negative electrode plate are alternately stacked, and a storage cell in which a separator is inserted between the positive electrode plate and the negative electrode plate adjacent to each other, each of the positive electrode plates includes a positive electrode current collector, A positive electrode active material layer formed on both surfaces of the positive electrode current collector, penetrating the positive electrode current collector from the outer surface of one of the positive electrode active material layers, and outside of the other positive electrode active material layer At least one first opening reaching the surface is provided, and the positive electrode active material layer can reversibly carry lithium ions or anions,
Each of the negative electrode plates includes a negative electrode current collector and a negative electrode active material layer formed on both surfaces of the negative electrode current collector, and the negative electrode current collector is disposed from one outer surface of the negative electrode active material layer. At least one second opening penetrating to the outer surface of the other negative electrode active material layer is provided, and the negative electrode active material layer contains a material capable of occluding and releasing lithium ions, A power storage cell that stores ions is provided.

According to another aspect of the invention,
Forming a positive electrode active material layer on both sides of the positive electrode current collector;
Forming a negative electrode active material layer on both sides of the negative electrode current collector;
A first opening reaching the positive electrode current collector and the positive electrode active material layer formed on both surfaces thereof from the outer surface of one of the positive electrode active material layers to the outer surface of the other positive electrode active material layer Forming a positive electrode plate by forming
A second active material layer formed on both sides of the negative electrode current collector and both sides thereof, from the outer surface of one of the negative electrode active material layers to the outer surface of the other negative electrode active material layer. Forming a negative electrode plate by forming an opening;
The positive electrode plate and the negative electrode plate are alternately laminated, a separator is inserted between the positive electrode plate and the negative electrode plate adjacent to each other, and a lithium material is disposed so as to contact at least one of the negative electrode plates Forming the electrode laminate,
There is provided a method of manufacturing a storage cell comprising: a step of pre-doping lithium into the negative electrode active material layer in a state where the electrode laminate is housed in a container and the container is filled with an electrolytic solution.

  By forming the first opening and the second opening in the positive electrode plate and the negative electrode plate, respectively, the lithium doping time can be shortened. In addition, the opening is formed after the positive electrode active material layer and the negative electrode active material layer are formed. For this reason, at the time of formation of a positive electrode active material layer and a negative electrode active material layer, the fall of workability | operativity by the raw material of an active material layer passing opening can be prevented.

1A is an exploded plan view of a storage cell according to the embodiment, and FIG. 1B is a cross-sectional view taken along one-dot chain line 1B-1B in FIG. 1A. 2 is a cross-sectional view taken along one-dot chain line 2-2 in FIG. 1A. FIG. 3 is a cross-sectional view illustrating an active material layer forming step in the method for manufacturing a storage cell according to the embodiment. FIG. 4 is a plan view showing a copper foil punching process in the method of manufacturing a storage cell according to the embodiment. FIG. 5A is a cross-sectional view showing a lithium pre-doping step in the method of manufacturing a storage cell according to the embodiment, and FIG. 5B is a cross-sectional view showing a lithium ion transport route. FIG. 6 is a cross-sectional view illustrating a lithium pre-doping step in a method for manufacturing a storage cell according to a modification of the embodiment. 7A to 7D are plan views of a negative electrode plate of a storage cell according to a modification of the embodiment.

  FIG. 1A is an exploded plan view of a power storage cell according to the embodiment. The electrode laminate 15 is sandwiched and sealed between a pair of laminate films. FIG. 1A is a plan view showing a state in which one of the laminate films is removed. An electrode laminate 15 is disposed on the first laminate film 10.

  The electrode laminate 15 includes negative plates 11 and positive plates 12 that are alternately laminated. A separator 13 is inserted between the negative electrode plate 11 and the positive electrode plate 12 adjacent to each other.

  Each negative electrode plate 11 includes a square or rectangular negative electrode storage region 11A and a smaller negative electrode connection region 11B. The negative electrode connection region 11B extends outward from a region of one edge of the negative electrode storage region 11A that is biased to one end from the center. Similarly, the positive electrode plate 12 includes a positive electrode storage region 12A and a positive electrode connection region 12B.

  The negative electrode plate 11 and the positive electrode plate 12 are aligned so that the negative electrode storage region 11A and the positive electrode storage region 12A overlap. Further, the negative electrode connection regions 11B of the negative electrode plate 11 overlap each other, and the positive electrode connection regions 12B of the positive electrode plate 12 overlap each other. The negative electrode connection region 11B and the positive electrode connection region 12B do not overlap. The separator 13 is slightly larger than the negative electrode storage region 11A and the positive electrode storage region 12A. The negative electrode connection region 11 </ b> B and the positive electrode connection region 12 </ b> B extend outward from the edge of the separator 13.

  A negative electrode tab 17 is connected to the negative electrode connection region 11B, and a positive electrode tab 18 is connected to the positive electrode connection region 12B. The negative electrode tab 17 and the positive electrode tab 18 are drawn out to the outside of the edge of the first laminate film 10.

  Each of the negative electrode plate 11 and the positive electrode plate 12 has at least one (seven in FIG. 1A) opening 11C and opening 12C. The opening 11C and the opening 12C have a slit-like planar shape that is long in one direction. The negative electrode plate 11 and the positive electrode plate 12 are aligned so that the opening 11C and the opening 12C overlap. That is, the opening 11C and the opening 12C are arranged at the same position in the in-plane direction.

  FIG. 1B is a cross-sectional view taken along one-dot chain line 1B-1B in FIG. 1A. The electrode laminate 15 is sandwiched between the first laminate film 10 and the second laminate film 20. The second laminate film 20 is thermally welded to the first laminate film 10 in the vicinity of the outer periphery. The first laminate film 10 and the second laminate film 20 constitute a container for a storage cell. The container is filled with the electrolytic solution 22.

  The first laminate film 10 is substantially flat, and the second laminate film 20 is deformed according to the outer shape of the electrode laminate 15. In addition, it is good also as a structure where both laminate films deform | transform according to the external shape of the electrode laminated body 15. FIG.

  The negative electrode plates 11 and the positive electrode plates 12 are alternately stacked. A separator 13 is inserted between the negative electrode plate 11 and the positive electrode plate 12. An opening 11 </ b> C is formed in the negative electrode plate 11, and an opening 12 </ b> C is formed in the positive electrode plate 12.

  The negative electrode plate 11 includes a negative electrode current collector 11D and a negative electrode active material layer 11E formed on both surfaces thereof. The negative electrode active material layer 11E is formed over the entire area of the negative electrode storage region 11A illustrated in FIG. 1A. The opening 11C penetrates the negative electrode current collector 11D in the thickness direction from the outer surface of one negative electrode active material layer 11E and reaches the outer surface of the other negative electrode active material layer 11E. The positive electrode plate 12 includes a positive electrode current collector 12D and a positive electrode active material layer 12E formed on both surfaces thereof. The positive electrode active material layer 12E is formed over the entire area of the positive electrode storage region 12A illustrated in FIG. 1A. The opening 12C penetrates the positive electrode current collector 12D in the thickness direction from the outer surface of one positive electrode active material layer 12E and reaches the outer surface of the other positive electrode active material layer 12E.

  FIG. 2 shows a cross-sectional view taken along one-dot chain line 2-2 in FIG. 1A. The electrode laminate 15 and the electrolytic solution 22 are accommodated in a container composed of the first laminate film 10 and the second laminate film 20. Negative electrode plates 11 and positive electrode plates 12 are alternately stacked, and a separator 13 is inserted between them. A negative electrode active material layer 11E is formed on both surfaces of the negative electrode storage region 11A in the negative electrode current collector 11D. The negative electrode active material layer 11E is not formed on both surfaces of the negative electrode connection region 11B.

  The negative electrode connection regions 11 </ b> B of the plurality of negative electrode plates 11 are stacked and connected to the negative electrode tab 17. For example, ultrasonic welding is applied to these connections. The negative electrode tab 17 passes through between the first laminate film 10 and the second laminate film 20 and is led out of the container.

  Similarly, the positive electrode connection regions 12B shown in FIG. 1A are also stacked on each other and ultrasonically welded to the positive electrode tab 18.

  Metal foil is used for the negative electrode current collector 11D and the positive electrode current collector 12D. As an example, a copper foil having a thickness of about 14 μm is used for the negative electrode current collector 11D, and an aluminum foil or a copper foil having a thickness of about 20 μm is used for the positive electrode current collector 12D.

  The negative electrode active material layer 11E is formed by applying a slurry containing a powder of a material capable of occluding and releasing lithium ions to the surface of the negative electrode current collector 11D and then drying the slurry. Examples of such materials include graphite, non-graphitizable carbon, and graphitizable carbon. As an example, a mixture containing spherical artificial graphite, acetylene black, carboxymethyl cellulose (CMC), and styrene butadiene rubber (SBR) can be used for the negative electrode active material layer 11E. The positive electrode active material layer 12E is formed by applying a slurry containing a powder of a material capable of reversibly supporting lithium ions or anions to the surface of the positive electrode current collector 11D and then drying the slurry. An example of such a material is activated carbon. As an example, a mixture containing activated carbon, ketjen black, CMC, and SBR can be used for the positive electrode active material layer 12E.

  For the separator 13, a material having ion permeability and capable of electrically separating the positive electrode plate 11 and the negative electrode plate 12 is used. As an example, a porous film made of polyethylene, polypropylene, aramid, polyethylene terephthalate, cellulose, cellophane, or the like is used.

  With reference to FIG.3 and FIG.4, the preparation methods of the negative electrode plate 11 are demonstrated. The positive electrode plate 12 is also produced by the same method.

  As shown in FIG. 3, a copper foil 35 serving as the negative electrode current collector 11 </ b> D is wound around the feeding roll 30. The copper foil 35 fed out from the feeding roll 30 is wound around the winding roll 33 via the rollers 31 and 32. A slurry reservoir 36 containing a powder of a negative electrode active material is accommodated in the slurry reservoir 36. The slurry 37 is in contact with the surface of the copper foil 35 along the cylindrical surface of the roller 31. When the copper foil 35 passes through the slurry reservoir 36, the slurry 37 is applied to the surface of the copper foil 35.

  When the copper foil 35 coated with the slurry 37 passes through the drying device 39, the solvent of the slurry 37 is vaporized, and the negative electrode active material layer 40 is formed. The copper foil 35 on which the negative electrode active material layer 40 is formed is wound around the winding roll 33 via the roller 32. The negative electrode active material layer 40 can be formed on both surfaces of the copper foil 35 by inverting the front and back of the copper foil 35 and performing the same treatment.

  The slurry 37 is produced by mixing a carbon material powder serving as a negative electrode active material and a polyvinylidene fluoride resin in a weight ratio of 95: 5, and adding N-methyl-2-pyrrolidinone (NMP) as a solvent. By adjusting the amount of the solvent, the viscosity of the slurry 37 can be adjusted.

  In the embodiment, no openings or voids are formed in the copper foil 35 when the slurry 37 is applied. Since the slurry 37 does not drip through the opening or the gap, workability when applying the slurry 37 can be improved.

  In FIG. 4, the top view of the copper foil 35 in which the negative electrode active material layer 40 was formed is shown. The negative electrode active material layer 40 is not applied in the vicinity of both ends in the width direction of the strip-shaped copper foil 35. The negative electrode plate 11 is obtained by punching the copper foil 35 and the negative electrode active material layer 40 using the punching die 42. Simultaneously with the punching, an opening 11C is formed.

  In the example, in order to punch the copper foil 35 after forming the negative electrode active material layer 40, as shown in FIG. It penetrates 11D and reaches the outer surface of the other negative electrode active material layer 11E. The cross-sectional shape perpendicular to the thickness direction and the size of the cross section of the opening 11 </ b> C are substantially the same at any position in the thickness direction of the negative electrode plate 11.

  Next, with reference to FIG. 5A, the manufacturing method of the electrical storage cell by an Example is demonstrated. A lithium foil 23 is placed on the first laminate film 10, and a negative electrode plate 11, a separator 13, a positive electrode plate 12, and a separator 13 are stacked on the lithium foil 23 in this order. A separator 13 may be inserted between the lithium foil 23 and the negative electrode plate 11. At the top, the positive electrode plate 12 is disposed. At this time, alignment is performed so that the opening 11C of the negative electrode plate 11 and the opening 12C of the positive electrode plate 12 are arranged at the same position in the in-plane direction. Normally, the opening 11C and the opening 12C are arranged so that the alignment of the openings 11C and 12C is completed when the outer peripheral lines of the negative electrode plate 11 and the positive electrode plate 12 are aligned.

The second laminate film 20 is disposed on the electrode laminate 15 including the negative electrode plate 11, the positive electrode plate 12, and the separator 13, and is thermally welded to the first laminate film 10 at the outer peripheral portion. At this time, an opening is left in a part of the outer periphery. An electrolytic solution 22 is filled into the container composed of the first laminate film 10 and the second laminate film 20 through the opening. By filling the electrolytic solution 22, the lithium foil 23 is electrically connected to the negative electrode plate 11 and the positive electrode plate 12. As an example, LiPF ₆ is used as the solute of the electrolytic solution 22, and a mixed solution of ethylene carbonate and dimethyl carbonate is used as the solvent. In addition, you may use a propylene carbonate as a solvent. The concentration of the solute is, for example, 1 mol / L. After filling with the electrolytic solution 22, the opening of the container is vacuum-sealed by heat welding. In this state, the negative electrode active material layer 11E is pre-doped with lithium by leaving it in a room temperature environment. The thickness of the lithium foil 23 is set so that the lithium foil 23 disappears after pre-doping. After the pre-doping, lithium ions are occluded in the negative electrode active material layer 11E.

  As shown in FIG. 5B, lithium atoms in the lithium foil 23 are ionized and transported in the thickness direction through the opening 11C, the separator 13, and the opening 12C. Lithium ions are doped into the negative electrode active material layer 11E of the negative electrode plate 11 from the side surface of the opening 11C.

  The dimension in the thickness direction of the electrode laminate 15 is smaller than the dimension in the in-plane direction. The required time when lithium ions are transported in the thickness direction through the opening 11C, the separator 13, and the opening 12C is shorter than the required time when transported in the negative electrode active material layer 11E in the in-plane direction. . For this reason, the doping time of lithium can be shortened.

  In the embodiment, the lithium foil 23 is used as the lithium supply source, but other members that can supply lithium ions to the electrolyte 22 may be used.

  Moreover, in the said Example, the negative electrode active material layer 11E is formed in both surfaces of the negative electrode plate 11 arrange | positioned at the bottom of the electrode laminated body 15, and the positive electrode active material is formed in both surfaces of the positive electrode plate 12 arrange | positioned at the top. Layer 12E was formed. The outermost surfaces of the outermost negative electrode plate 11 and the positive electrode plate 12 of the electrode laminate 15 do not face the positive electrode plate 12 and the negative electrode plate 11, respectively. For this reason, the negative electrode active material layer 11E may not be formed on the outer surface of the outermost negative electrode plate 11. Similarly, the positive electrode active material layer 12E may not be formed on the outer surface of the outermost positive electrode plate 12.

  With reference to FIG. 6, the manufacturing method of the electrical storage cell by the modification of an Example is demonstrated. Description will be made by paying attention to different points as compared with the embodiment shown in FIG. 5A. In the above example, as shown in FIG. 5A, the lithium foil 23 was in contact with the outer surface of the outermost negative electrode plate 11 of the electrode laminate 15. In the modification shown in FIG. 6, the lithium foil 23 is in contact with the negative electrode plate 11 disposed inside the electrode laminate 15. In this modification, lithium ions are transported from the lithium foil 23 in the vertical direction.

  Thus, the position where the lithium foil 23 is disposed is not particularly limited. However, the lithium foil 23 is preferably in contact with the negative electrode plate 11 in order to dope the negative electrode active material layer 11E with lithium ions.

  In the above-described embodiment, the opening 11C formed in the negative electrode plate 11 and the opening 12C formed in the positive electrode plate 12 are formed into slits that are long in one direction, but other shapes may be used. For example, as shown in FIG. 7A, the planar shape of the openings 11C may be a circle or an ellipse, and the openings 11C may be arranged in a matrix.

  Furthermore, unlike the circle or ellipse shown in FIG. 7A, one end of the opening 11C may reach the edge of the negative electrode plate 11, as shown in FIG. 7B. The opening 11C illustrated in FIG. 7B can also be referred to as “cut”. As shown in FIG. 7C, the longitudinal directions of the openings 11C do not need to be aligned. An opening 11C that is long in the vertical direction and an opening 11C that is long in the horizontal direction may be formed. As shown in FIG. 7D, the widths of the openings 11C may be uneven.

  Moreover, although the example in which the electrode laminate 15 has a flat plate shape has been described in the above embodiment, lithium ion pre-doping may be performed while the electrode laminate 15 is wound and inserted into a cylindrical container. Thereby, a cylindrical power storage device is obtained.

  In the above embodiment, the lithium ion capacitor is adopted as the storage cell. However, the storage cell and the manufacturing method thereof according to the above embodiment can also be applied to the lithium ion secondary battery.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 1st laminated film 11 Negative electrode plate 11A Negative electrode electrical storage area | region 11B Negative electrode connection area | region 11C Opening 11D Negative electrode collector 11E Negative electrode active material layer 12 Positive electrode plate 12A Positive electrode electrical storage area | region 12B Positive electrode connection area | region 12C Opening 12D Positive electrode collector 12E Material layer 13 Separator 15 Electrode laminate 17 Negative electrode tab 18 Positive electrode tab 20 Second laminate film 22 Electrolytic solution 23 Lithium foil 30 Feeding rolls 31, 32 Roller 33 Winding roll 35 Copper foil 36 Slurry reservoir 37 Slurry 39 Drying device 40 Positive electrode active material layer 42 Punching die

Claims (8)

A positive electrode plate and a negative electrode plate are alternately stacked, and a storage cell in which a separator is inserted between the positive electrode plate and the negative electrode plate adjacent to each other, each of the positive electrode plates includes a positive electrode current collector, A positive electrode active material layer formed on both surfaces of the positive electrode current collector, wherein a first cut is formed inward from an edge of the positive electrode plate, and the positive electrode active material layer contains lithium ions or anions. Reversibly supportable,
Each of the negative electrode plates includes a negative electrode current collector and a negative electrode active material layer formed on both surfaces of the negative electrode current collector, and a second cut is formed inward from the edge of the negative electrode plate. The negative electrode active material layer includes a material capable of inserting and extracting lithium ions, and stores lithium ions.   The electrical storage cell according to claim 1, wherein the first cut and the second cut have a slit shape that is long in one direction.   The electrical storage cell according to claim 1 or 2, wherein the first cut and the second cut are arranged at positions overlapping in the stacking direction. A positive electrode plate and a negative electrode plate are alternately stacked, and a storage cell in which a separator is inserted between the positive electrode plate and the negative electrode plate adjacent to each other, each of the positive electrode plates includes a positive electrode current collector, A positive electrode active material layer formed on both surfaces of the positive electrode current collector, penetrating the positive electrode current collector from the outer surface of one of the positive electrode active material layers, and outside of the other positive electrode active material layer At least one first opening reaching the surface is provided, and the positive electrode active material layer can reversibly carry lithium ions or anions,
Each of the negative electrode plates includes a negative electrode current collector and a negative electrode active material layer formed on both surfaces of the negative electrode current collector, and the negative electrode current collector is disposed from one outer surface of the negative electrode active material layer. At least one second opening penetrating to the outer surface of the other negative electrode active material layer is provided, and the negative electrode active material layer contains a material capable of occluding and releasing lithium ions, A storage cell that stores ions.   The storage cell according to claim 4, wherein the first opening and the second opening have a slit shape that is long in one direction.   The electrical storage cell according to claim 4 or 5, wherein the first opening and the second opening are arranged at positions overlapping in the stacking direction. Forming a positive electrode active material layer on both sides of the positive electrode current collector;
Forming a negative electrode active material layer on both sides of the negative electrode current collector;
A step of forming a positive electrode plate from the positive electrode current collector and the positive electrode active material layer formed on both surfaces thereof, wherein the first cut is formed from the edge of the positive electrode plate toward the inside. Forming a positive electrode plate;
The step of forming a negative electrode plate from the negative electrode current collector and the negative electrode active material layer formed on both surfaces thereof, wherein the second cut is formed inward from the edge of the negative electrode plate. Forming a negative electrode plate;
The positive electrode plate and the negative electrode plate are alternately laminated, and a separator is inserted between the positive electrode plate and the negative electrode plate adjacent to each other, so that at least one of the negative electrode plates is in contact, or the separator Forming an electrode laminate in which a lithium material is disposed so as to face the negative electrode plate via
A process for producing a storage cell, comprising: storing the electrode laminate in a container, and pre-doping lithium into the negative electrode active material layer in a state in which the container is filled with an electrolyte solution. Forming a positive electrode active material layer on both sides of the positive electrode current collector;
Forming a negative electrode active material layer on both sides of the negative electrode current collector;
A first opening reaching the positive electrode current collector and the positive electrode active material layer formed on both surfaces thereof from the outer surface of one of the positive electrode active material layers to the outer surface of the other positive electrode active material layer Forming a positive electrode plate by forming
A second opening extending from the outer surface of one of the negative electrode active material layers to the outer surface of the other negative electrode active material layer to the negative electrode current collector and the negative electrode active material layers formed on both sides thereof Forming a negative electrode plate by forming
The positive electrode plate and the negative electrode plate are alternately laminated, and a separator is inserted between the positive electrode plate and the negative electrode plate adjacent to each other, so that at least one of the negative electrode plates is in contact, or the separator Forming an electrode laminate in which a lithium material is disposed so as to face the negative electrode plate via
A process for producing a storage cell, comprising: storing the electrode laminate in a container, and pre-doping lithium into the negative electrode active material layer in a state in which the container is filled with an electrolyte solution.

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