Lithium-ion secondary battery element and lithium-ion secondary battery

Abstract

To provide a small lithium ion secondary battery element having high energy density, and a lithium ion secondary battery.SOLUTION: In a lithium ion secondary battery element, a positive electrode and a negative electrode coated with a double-side active material of a current collector have a rectangular active material layer coated with an active material and an active material non-coated part coated with no active material; the active material non-coated part is located along a part of a peripheral part of the current collector; the active material layer is composed of a thin part and a flat part; a positive electrode active material layer and a negative electrode active material layer are layered so that they overlap each other; the positive electrode and the negative electrode active material non-coated parts are superimposed to be located on opposite sides of the rectangle; a boundary between the negative electrode active material coated part and the non-coated part is located nearer on a negative electrode current collector peripheral side than a positive electrode current collector peripheral part adjacent to the negative electrode active material non-coated part; a boundary between a negative electrode active material layer flat part and a thin part is located nearer on a central side of a negative electrode current collector than a positive electrode current collector peripheral part adjacent to the negative electrode active material non-coated part; and density of the negative electrode active material layer thin part is the same as or smaller than density of the flat part.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a non-aqueous electrolyte battery, particularly a lithium ion secondary battery and a lithium ion battery constituting the battery. The present invention relates to a lithium ion secondary battery element, and a method for manufacturing a lithium ion secondary battery element. [Background technology]

[0002] Non-aqueous electrolyte batteries are used in automobiles, including hybrid and electric vehicles. Lithium-ion secondary batteries are being used as the power supply batteries for such vehicles. Lithium-ion secondary batteries have various characteristics such as output characteristics, energy density, capacity, lifespan, and high-temperature stability. In particular, in order to make batteries smaller, Improving the product energy density is an urgent issue. Various improvements have been made to the construction of electrolyte-containing batteries.

[0003] Patent Document 1 discloses an electrode for a secondary battery. The electrode of Patent Document 1 includes an active material The coating layer has a coated portion and an uncoated portion, and a thin layer is formed on at least a part of the outer periphery of the coating portion. It is characterized by including a high density portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015-129320 Summary of the Invention [Problem to be solved by the invention]

[0005] The electrode proposed in Patent Document 1 is locally raised by an insulating member attached to the electrode end. In order to prevent the active material from becoming a curved shape, the thickness is thin and the density is high at the outer periphery of the active material application part. In Patent Document 1, a portion is provided at a location facing the insulating member provided on the positive electrode. The overlapping negative electrode portion is considered to have no substantial involvement in the operation of the battery, and lithium-ion batteries are used in this portion. To prevent the intrusion of on, a high density area is provided on the outer periphery of the negative electrode. If a high density portion is provided, that portion will not be involved in the operation of the battery, so the area of ​​the negative electrode can be increased. This would contradict the intention to increase the energy density of the battery.

[0006] The present invention relates to a small lithium ion secondary battery element having a high energy density, and The object is to provide a high-capacity lithium-ion secondary battery using this. [Means for solving the problem]

[0007] The lithium ion secondary battery element according to an embodiment of the present invention comprises: A positive electrode active material is applied to at least a portion of both surfaces of the positive electrode current collector in substantially the same shape. a positive electrode formed by The positive electrode current collector has a generally rectangular positive electrode active material layer coated with the positive electrode active material, and a positive electrode active material layer. and a positive electrode active material uncoated portion where no material is coated, and the positive electrode active material uncoated portion is located along at least a portion of the periphery of the current collector; the positive electrode active material layer is composed of a thin portion of the positive electrode active material layer and a flat portion of the positive electrode active material layer, the positive electrode; A negative electrode active material is applied to at least a part of both surfaces of the negative electrode current collector in substantially the same shape. a negative electrode formed by The negative electrode current collector is generally a layer having substantially the same shape as the positive electrode active material layer to which the negative electrode active material is applied. The negative electrode active material has a rectangular coated portion and a non-coated portion where the negative electrode active material is not coated. the negative electrode active material uncoated portion is located along at least a part of the peripheral edge portion of the negative electrode current collector, The negative electrode active material layer is composed of a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer. , the negative electrode; and the generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode. The positive electrode and the negative electrode are stacked together so that the rectangles of the positive electrode and the negative electrode are overlapped with each other. The present invention also provides a lithium ion secondary battery element, wherein the positive electrode active material uncoated portion of the positive electrode and the The positive electrode and the negative electrode are arranged so that the negative electrode active material uncoated portions of the negative electrode are positioned on opposite sides of the rectangle. The poles are superimposed, The boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is adjacent to the negative electrode active material uncoated portion. the negative electrode current collector is located closer to the periphery of the negative electrode current collector than the periphery of the positive electrode current collector that the negative electrode current collector faces; The boundary between the flat portion of the negative electrode active material layer and the thin portion of the negative electrode active material layer is the negative electrode active material uncoated portion. is located closer to the center of the negative electrode current collector than the peripheral edge portion of the adjacent positive electrode current collector, The density of the thin portion of the negative electrode active material layer is equal to or greater than the density of the flat portion of the negative electrode active material layer. It is characterized by being smaller than

[0008] Furthermore, a lithium ion secondary battery element according to another embodiment of the present invention comprises: A positive electrode active material is applied to at least a portion of both surfaces of the positive electrode current collector in substantially the same shape. a positive electrode formed by The positive electrode current collector has a generally rectangular positive electrode active material layer coated with the positive electrode active material, and a positive electrode active material layer. and a positive electrode active material uncoated portion where no material is coated, and the positive electrode active material uncoated portion is located along at least a portion of the periphery of the current collector; the positive electrode active material layer is composed of a thin portion of the positive electrode active material layer and a flat portion of the positive electrode active material layer, the positive electrode having an insulating member covering at least a part of the positive electrode active material uncoated portion; A negative electrode active material is applied to at least a part of both surfaces of the negative electrode current collector in substantially the same shape. a negative electrode formed by The negative electrode current collector is generally a layer having substantially the same shape as the positive electrode active material layer to which the negative electrode active material is applied. The negative electrode active material has a rectangular coated portion and a non-coated portion where the negative electrode active material is not coated. the negative electrode active material uncoated portion is located along at least a part of the peripheral edge portion of the negative electrode current collector, The negative electrode active material layer is composed of a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer. , the negative electrode; and the generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode. The positive electrode and the negative electrode are stacked together so that the rectangles of the positive electrode and the negative electrode are overlapped with each other. The present invention also provides a lithium ion secondary battery element, wherein the positive electrode active material uncoated portion of the positive electrode and the the negative electrode active material uncoated portion of the negative electrode is located on the same side of the rectangle, The boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is adjacent to the insulating member. Located in The boundary between the thin portion of the negative electrode active material layer and the flat portion of the negative electrode active material layer is Located next to each other, The density of the thin portion of the negative electrode active material layer is equal to or greater than the density of the flat portion of the negative electrode active material layer. It is characterized by being smaller than

[0009] Furthermore, a method for manufacturing a lithium ion secondary battery element according to another embodiment of the present invention includes the steps of: A positive electrode active material is applied to at least a portion of both surfaces of the positive electrode current collector in substantially the same shape. a positive electrode and A negative electrode active material is applied to at least a part of both surfaces of the negative electrode current collector in substantially the same shape. a negative electrode, A method for manufacturing a lithium ion secondary battery element by stacking A positive electrode active material-containing slurry containing a positive electrode active material and a solvent is extracted from a portion of the positive electrode current collector. The cathode active material is continuously applied in one direction to provide a positive electrode active material-coated portion and a positive electrode active material-uncoated portion, The active material coated portion is generally rectangular, and the positive electrode active material uncoated portion is a small portion of the peripheral edge of the positive electrode current collector. Located along at least part of the The entire positive electrode active material coated portion is generally uniformly pressed with a predetermined pressure to form a thin layer of the positive electrode active material. a step of simultaneously forming a positive electrode active material layer flat portion and a positive electrode active material layer flat portion to obtain the positive electrode; A negative electrode active material-containing slurry containing a negative electrode active material and a solvent is extracted from a portion of the negative electrode current collector. The negative electrode active material is continuously applied in one direction to provide a negative electrode active material-coated portion and a negative electrode active material-uncoated portion, The active material coated portion is generally rectangular in shape, which is substantially the same as the positive electrode active material coated portion, and the negative electrode active material uncoated portion is the fabric portion is located along at least a portion of the peripheral edge of the positive electrode current collector, The entire negative electrode active material application area is generally uniformly pressed with a predetermined pressure to form a thin negative electrode active material layer. a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer are simultaneously formed, and the density of the thin portion of the negative electrode active material layer is obtaining the negative electrode having a density equal to or less than that of the flat portion of the porous layer; The generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode, a step of overlapping the positive electrode and the negative electrode so that the rectangles substantially overlap each other, At this time, the positive electrode active material uncoated portion of the positive electrode and the negative electrode active material uncoated portion of the negative electrode are in the rectangular shape. The boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is located on the opposite sides of the shape. a portion of the negative electrode current collector adjacent to the peripheral edge of the positive electrode current collector adjacent to the portion not coated with the negative electrode active material; The boundary between the flat portion of the negative electrode active material layer and the thin portion of the negative electrode active material layer is the negative electrode active material uncoated portion. The positive electrode current collector is positioned closer to the center of the negative electrode current collector than the peripheral edge of the adjacent positive electrode current collector. the step of superposing the negative electrode on the At least includes.

[0010] Furthermore, a method for manufacturing a lithium ion secondary battery element according to another embodiment of the present invention includes the steps of: A positive electrode active material is applied to at least a portion of both surfaces of the positive electrode current collector in substantially the same shape. a positive electrode and A negative electrode active material is applied to at least a part of both surfaces of the negative electrode current collector in substantially the same shape. a negative electrode, A method for manufacturing a lithium ion secondary battery element by stacking A positive electrode active material-containing slurry containing a positive electrode active material and a solvent is extracted from a portion of the positive electrode current collector. The cathode active material is continuously applied in one direction to provide a positive electrode active material-coated portion and a positive electrode active material-uncoated portion, The active material coated portion is generally rectangular, and the positive electrode active material uncoated portion is a small portion of the peripheral edge of the positive electrode current collector. Located along at least part of the The entire positive electrode active material coated portion is generally uniformly pressed with a predetermined pressure to form a thin layer of the positive electrode active material. The positive electrode active material layer flat portion and the positive electrode active material layer flat portion are simultaneously formed, and at least a part of the positive electrode active material uncoated portion is covered. a step of providing an insulating member so as to obtain the positive electrode; A negative electrode active material-containing slurry containing a negative electrode active material and a solvent is extracted from a portion of the negative electrode current collector. The negative electrode active material is continuously applied in one direction to provide a negative electrode active material-coated portion and a negative electrode active material-uncoated portion, The active material coated portion is generally rectangular in shape, which is substantially the same as the positive electrode active material coated portion, and the negative electrode active material uncoated portion is the fabric portion is located along at least a portion of the peripheral edge of the positive electrode current collector, The entire negative electrode active material application area is generally uniformly pressed with a predetermined pressure to form a thin negative electrode active material layer. a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer are simultaneously formed, and the density of the thin portion of the negative electrode active material layer is obtaining the negative electrode having a density equal to or less than that of the flat portion of the porous layer; The generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode, a step of overlapping the positive electrode and the negative electrode so that the rectangles substantially overlap each other, At this time, the positive electrode active material uncoated portion of the positive electrode and the negative electrode active material uncoated portion of the negative electrode are in the rectangular shape. The boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is located on the same side of the shape of the insulating film. The negative electrode active material layer has a thin portion and a flat portion, and the thin portion is positioned adjacent to the edge member. The positive electrode and the negative electrode are stacked together so that the flat portion of the positive electrode active material layer is adjacent to the flat portion of the positive electrode active material layer. The combining step: At least includes. [Effects of the Invention]

[0011] The lithium ion secondary battery element of the present invention is characterized by the density of the active material layer of each electrode and the stacking of each member. By adjusting the ratio of the positive and negative electrodes to the charge capacity, the deposition of metallic lithium can be prevented. This makes it possible to provide a battery with high energy density while maintaining the safety of the battery. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a plan view of one surface of a positive electrode used in the embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a positive electrode used in the embodiment. [Figure 3] FIG. 3 is a plan view of one surface of the negative electrode used in the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a negative electrode used in the embodiment. [Figure 5] FIG. 5 is a cross-sectional view of a lithium ion secondary battery element of the first embodiment, which is configured by stacking a positive electrode and a negative electrode. [Figure 6]6A and 6B are a plan view (FIG. 6A) of the lithium ion secondary battery element of FIG. 5 as viewed from direction A, and a plan view (FIG. 6B) as viewed from direction B. In FIG. [Figure 7] FIG. 7 is a cross-sectional view of a lithium ion secondary battery element according to the first embodiment, which is configured by stacking a positive electrode and a negative electrode. [Figure 8] FIG. 8 is a cross-sectional view of a lithium ion secondary battery element according to the second embodiment, which is configured by stacking a positive electrode and a negative electrode. [Figure 9] 9A and 9B are a plan view (FIG. 9A) of the lithium ion secondary battery element of FIG. 8 as seen from direction A, and a plan view (FIG. 9B) as seen from direction B. In FIG. [Figure 10] FIG. 10 is a cross-sectional view illustrating a lithium ion secondary battery element according to the first embodiment in which the positive electrode and the negative electrode are superimposed in such a positional relationship that the portion uncoated with the positive electrode active material is adjacent to the portion coated with the negative electrode active material. DETAILED DESCRIPTION OF THE INVENTION

[0013] The embodiments of the present invention will be described below with reference to the accompanying drawings. The secondary battery element has a positive electrode current collector and a positive electrode formed on at least a part of the positive electrode current collector. The positive electrode current collector includes a positive electrode coated with a positive electrode active material. The cathode active material layer has a rectangular shape, and a cathode active material uncoated portion where the cathode active material is not coated. The electrode active material uncoated portion is located along at least a part of the peripheral edge of the positive electrode current collector, and The positive electrode active material layer is composed of a thin portion of the positive electrode active material layer and a flat portion of the positive electrode active material layer.

[0014] In the embodiment, the positive electrode is formed by applying or rolling a positive electrode current collector such as a metal foil and drying it. The positive electrode is a thin plate or sheet-like battery component on which an active material layer is formed. The positive electrode active material layer includes a positive electrode active material and is coated on both sides of the positive electrode active material layer. In the fine print, when we say "positive electrode active material," we mean the positive electrode in the original sense that is responsible for the conductivity during charging and discharging of the battery. It may refer to a mixture of an active material, a binder, and, if necessary, a conductive additive. When the two surfaces of the positive electrode current collector are viewed from each side, the quality is that the material is coated on the entire surface of the positive electrode current collector. It is not necessary for the coating material to be applied to the positive electrode current collector, but it is sufficient that the coating material is applied to at least a part of the positive electrode current collector. The cathode active material layer is generally rectangular and has a positive electrode active material layer coated with the positive electrode active material, and the cathode active material layer is not coated with the positive electrode active material. The positive electrode active material is not applied to the positive electrode.

[0015] In the embodiment, the positive electrode active material is applied in substantially the same shape to two positive electrode current collectors. When the surfaces are viewed from each side, the positive electrode active materials are arranged in substantially the same shape; In addition, when looking at the cross section of the positive electrode, the positive electrode active material has an almost symmetrical shape with the positive electrode current collector as the boundary. It means both that the

[0016] The positive electrode active material layer has a thin portion where the positive electrode active material is thin and a thin portion where the positive electrode active material is almost uniformly distributed. The positive electrode active material layer may be formed by applying a positive electrode active material layer having a flat portion to a uniform thickness. The thin portion and the flat portion of the positive electrode active material layer may be located anywhere in the positive electrode active material layer. For example, the thin portion of the positive electrode active material layer can be located at the periphery of the positive electrode active material layer. The thickness of the positive electrode active material layer gradually decreases toward the boundary between the material-coated portion and the positive electrode active material-uncoated portion. That is, the thin portion of the positive electrode active material layer may be a portion where the positive electrode active material is not applied and the positive electrode active material is not applied. The thickness of the positive electrode active material layer is gradually reduced toward the boundary with the coating area. The shape of the positive electrode active material layer is generally rectangular. Here, "generally rectangular" means When the two surfaces of the positive electrode current collector are viewed from each side, the shape of the positive electrode active material layer is a quadrilateral (rectangular). The positive electrode structure is as follows: The shape of the positive electrode current collector on which the positive electrode active material layer is provided is also generally rectangular. It is preferable to use a current collector having a shape such as an L-shape obtained by cutting out a part of a rectangle. It can also be done as follows.

[0017] A typical structure of a positive electrode will be explained using Fig. 1 and Fig. 2. Fig. 1 shows a positive electrode viewed from one side. In Fig. 1, 1 denotes a positive electrode; 11 denotes a positive electrode current collector; 12 denotes a positive electrode active material layer; The cathode active material coated portion 14 is a portion where the cathode active material is not coated. FIG. 2 is a cross-sectional view of the cathode. In the figure, 1 is a positive electrode; 21 is a positive electrode current collector; 22 is a positive electrode active material layer; 23 is a positive electrode active material coating portion; 24 In FIG. 1, one surface of the positive electrode current collector 11 is coated with the positive electrode active material. The positive electrode active material layer 12 is formed by spreading the positive electrode active material layer 12 over the The positive electrode active material coated portion 13 is a portion where the positive electrode active material layer 12 is not provided. 1, the positive electrode active material uncoated portion 14 is the peripheral portion of the positive electrode current collector 11. That is, in FIG. 1, the positive electrode current collector 1 has a roughly rectangular shape. A generally rectangular positive electrode active material layer 12 is provided on the positive electrode current collector 11, and a rectangular positive electrode active material layer 12 is provided on one side of the periphery of the positive electrode current collector 11. In FIG. 1, a positive electrode active material uncoated portion 14 is provided along the positive electrode current collector 11. On the other surface (the reverse side of the first surface, not shown), a positive electrode active material layer having substantially the same shape as that shown in FIG. It is being used.

[0018] On the other hand, in FIG. 2, a positive electrode active material is applied to the upper surface of a positive electrode current collector 21, and a positive electrode active material layer 22 The positive electrode active material is also applied to the lower surface of the positive electrode current collector 21 in the same manner. On each surface, the positive electrode active material layer 22 is formed. The portion where the positive electrode active material layer 22 is not provided is the positive electrode active material coated portion 23, and the portion where the positive electrode active material layer 22 is not provided is the positive electrode active material coated portion 23. As described above, in this embodiment, the positive electrode active material is substantially the same as that of the positive electrode active material. When the cross section of the positive electrode is viewed, the positive electrode current collector 21 is the boundary. This means that the electrode active material layers 22 are arranged in a substantially symmetrical shape.

[0019] The positive electrode active material layer may be composed of a thin portion of the positive electrode active material layer and a flat portion of the positive electrode active material layer. The thin portion of the positive electrode active material layer and the flat portion of the positive electrode active material layer are located at any position in the positive electrode active material layer. For example, the thin portion of the positive electrode active material layer may be located at the periphery of the positive electrode active material layer. FIG. 2 shows an example in which the thin portion of the positive electrode active material layer is provided on the periphery of the positive electrode active material layer. In FIG. 2, 25 denotes a thin portion of the positive electrode active material layer, and 26 denotes a flat portion of the positive electrode active material layer. The thin portion 25 of the positive electrode active material layer is a boundary portion between the positive electrode active material coated portion 23 and the positive electrode active material uncoated portion 24. The thickness of the positive electrode active material layer is formed so as to gradually decrease toward the center.

[0020] The lithium ion secondary battery element of the embodiment has a structure in which the negative electrode current collector is provided with a substantially identical shape on both sides thereof. The negative electrode includes a negative electrode having a negative electrode active material applied to at least a portion of both surfaces. The negative electrode active material layer is generally rectangular and has substantially the same shape as the positive electrode active material layer. a negative electrode active material uncoated portion where the negative electrode active material is not coated, The portion is located along at least a part of the peripheral edge of the negative electrode current collector, and further includes a negative electrode active material layer is composed of a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer.

[0021] In the embodiment, the negative electrode is formed by applying or rolling a negative electrode current collector such as a metal foil and then drying it. The negative electrode is a thin plate or sheet-like battery component on which an active material layer is formed. The negative electrode active material layer includes a negative electrode active material applied to both sides of the negative electrode active material layer. In the fine print, when we say negative electrode active material, we mean the negative electrode active material that is responsible for the conductivity of the battery, the binder, and the necessary In this case, it may mean a mixture with a conductive additive. When viewed from the negative electrode current collector side, it is not necessary for the coating to cover the entire surface of the negative electrode current collector. Preferably, the negative electrode current collector is a substantially solid negative electrode current collector coated with the negative electrode active material. The negative electrode active material layer has a rectangular shape, and a negative electrode active material uncoated portion where the negative electrode active material is not coated. are.

[0022] In the embodiment, the negative electrode active material is applied in substantially the same shape to two negative electrode current collectors. When the surface is viewed from each side, the negative electrode active material is arranged in substantially the same shape; In addition, when looking at the cross section of the negative electrode, the negative electrode active material has an almost symmetrical shape with the negative electrode current collector as the boundary. It means both that the

[0023] The negative electrode active material layer has a thin portion where the negative electrode active material is thin and a thin portion where the negative electrode active material is almost uniformly thick. The negative electrode active material layer may be formed by applying a flat portion of the negative electrode active material layer to a uniform thickness. The thin portion and the flat portion of the negative electrode active material layer may be located anywhere in the negative electrode active material layer. For example, the thin portion of the negative electrode active material layer can be located at the periphery of the negative electrode active material layer. The thickness of the negative electrode active material layer gradually decreases toward the boundary between the material-coated portion and the negative electrode active material-uncoated portion. That is, the thin portion of the negative electrode active material layer may be a portion between the negative electrode active material coated portion and the negative electrode active material uncoated portion. The thickness of the negative electrode active material layer is gradually reduced toward the boundary with the coating area. The negative electrode active material layer may have a generally rectangular shape. When the two surfaces of the negative electrode current collector are viewed from each side, the shape of the negative electrode active material layer is a quadrilateral (rectangular). The negative electrode structure is as follows: The shape of the negative electrode current collector on which the negative electrode active material layer is provided is also generally rectangular. It is preferable to use a current collector having a shape such as an L-shape obtained by cutting out a part of a rectangle. It can also be done as follows.

[0024] A typical structure of a negative electrode will be explained using Fig. 3 and Fig. 4. Fig. 3 shows a negative electrode viewed from one side. In Fig. 3, 2 is a negative electrode; 31 is a negative electrode current collector; 32 is a negative electrode active material layer; 33 is a negative The electrode active material coated portion 34 is a portion where the negative electrode active material is not coated. FIG. 4 is a cross-sectional view of the negative electrode. In the figure, 2 is a negative electrode; 41 is a negative electrode current collector; 42 is a negative electrode active material layer; 43 is a negative electrode active material coating portion; 44 In FIG. 3, one surface of the negative electrode current collector 31 is coated with the negative electrode active material. The negative electrode active material layer 32 is formed by spreading the negative electrode active material layer 32 over the surface of the negative electrode. The negative electrode active material coated portion 43 is a portion where the negative electrode active material layer 42 is not provided. 3, the negative electrode active material uncoated portion 44 is the peripheral portion of the negative electrode current collector 41. That is, in FIG. 3, the negative electrode current collector 31 has a roughly rectangular shape. The negative electrode active material layer 32 is generally rectangular and is disposed along one side of the peripheral edge of the negative electrode current collector 31. In FIG. 3, the negative electrode current collector 31 has a negative electrode active material uncoated portion 34. On one surface (the reverse side of the first surface, not shown) a negative electrode active material layer having substantially the same shape as that shown in FIG. It is being done.

[0025] On the other hand, in FIG. 4, a negative electrode active material is applied to the upper surface of a negative electrode current collector 41, and a negative electrode active material layer 42 The negative electrode active material is also applied to the lower surface of the negative electrode current collector 41 in the same manner. On each surface, the negative electrode active material layer 42 is formed. The portion where the negative electrode active material layer 42 is not provided is the negative electrode active material coated portion 43, and the portion where the negative electrode active material layer 42 is not provided is the negative electrode active material coated portion 43. As described above, in this embodiment, the negative electrode active material is applied to the non-coated portion 44. When the cross section of the negative electrode is viewed, the negative electrode current collector 41 is the boundary. This means that the electrode active material layers 42 are arranged in a substantially symmetrical shape.

[0026] The negative electrode active material layer may be composed of a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer. The thin portion of the negative electrode active material layer and the flat portion of the negative electrode active material layer are located at any position in the negative electrode active material layer. For example, the thin portion of the negative electrode active material layer may be located at the periphery of the negative electrode active material layer. FIG. 4 shows an example in which the thin portion of the negative electrode active material layer is provided on the periphery of the negative electrode active material layer. In FIG. 4, 45 denotes a thin portion of the negative electrode active material layer, and 46 denotes a flat portion of the negative electrode active material layer. The thin portion 45 of the electrode active material layer is located at the boundary between the negative electrode active material coated portion 43 and the negative electrode active material uncoated portion 44. The thickness of the negative electrode active material layer is formed so as to gradually decrease toward the negative electrode.

[0027] The lithium ion secondary battery element of the embodiment has the generally rectangular positive electrode active material layer of the positive electrode and The negative electrode active material layer is generally rectangular, and the rectangular portions of the negative electrode are arranged so that they overlap each other. The positive electrode and the negative electrode are stacked on top of each other. The generally rectangular negative electrode active material layer is formed by stacking the positive electrode and the negative electrode so that the rectangles are almost overlapping each other. The term "knead" refers to the state in which each side of the generally rectangular positive electrode active material layer and each side of the generally rectangular negative electrode active material layer are aligned. This means that the positive and negative electrodes are stacked so that they are roughly overlapping. When the shape of the material layer is rectangular, the shape of the negative electrode active material layer is approximately the same rectangle, The positive electrode active material layer and the negative electrode active material layer are arranged so that their long sides overlap each other. Here, the shape of the positive electrode active material layer and the shape of the negative electrode active material layer are The positive electrode active material layer and the negative electrode active material layer do not need to be exactly the same. There is no need to stack the positive electrode and the negative electrode so that they overlap exactly. The rectangle of the layer may have roughly the same shape, and the two may be roughly overlapped.

[0028] In this embodiment, the positive electrode active material uncoated portion of the positive electrode and the negative electrode active material uncoated portion of the negative electrode are: It is preferable that the positive electrode and the negative electrode are stacked so as to be positioned on opposite sides of a rectangle. The positive electrode active material uncoated portion and the negative electrode active material uncoated portion are positioned on opposite sides of the rectangle. The phrase "overlap the positive electrode and the negative electrode" means, for example, that the positive electrode active material uncoated portion is positioned at the corners of the positive electrode active material layer. When the negative electrode active material is located on the short side of the rectangular shape, the negative electrode active material uncoated portion is located on the opposite side of the rectangular shape of the negative electrode active material layer. This means that the part is located on the short side. Details will be described later with reference to the drawings.

[0029] In this embodiment, when the positive electrode and the negative electrode are stacked together, a thin film may be formed between the positive electrode and the negative electrode. A separator may also be disposed.

[0030] FIG. 5 shows a first embodiment of a lithium ion secondary battery constructed by stacking a positive electrode and a negative electrode. 5 is a cross-sectional view of the element. In FIG. 5, 1: positive electrode; 2: negative electrode; 3: separator; 151: positive Electrode current collector; 152: Positive electrode active material layer; 153: Positive electrode active material coated portion; 154: Positive electrode active material uncoated Fabric portion; 251: negative electrode current collector; 252: negative electrode active material layer; 253: negative electrode active material coating portion; 254 5: A portion where the negative electrode active material is not applied. In FIG. 5, the positive electrode 1, the separator 3, and the negative electrode 2 are Although they are written as if they are separated from each other, this is written for the sake of clarity in explaining each component. In an actual lithium ion secondary battery element, these components come into contact with each other. On the other hand, FIG. 6 shows the lithium ion secondary battery element of FIG. 5 in the A direction. 6a) is a plan view seen from direction B, and FIG. 6b) is a plan view seen from direction B. 1: positive electrode; 2: negative electrode; 3: separator; 161: positive electrode current collector; 162: positive electrode active material layer; 163: Positive electrode active material coated portion; 164: Positive electrode active material uncoated portion; 261: Negative electrode current collector; 262 : negative electrode active material layer; 263: negative electrode active material coated portion; 264: negative electrode active material uncoated portion.

[0031] In FIG. 6(a), the positive electrode active material uncoated portion 164 of the positive electrode is a rectangular positive electrode current collector 161. 6(b), the negative electrode active material uncoated portion 2 of the negative electrode is located along the short side. 64 is also positioned along the short side of the rectangular negative electrode current collector 261. 6(b) and the negative electrode are superimposed to form the battery element shown in FIG. The generally rectangular positive electrode active material layer 162 and the generally rectangular negative electrode active material layer 262 are The positive electrode 1 and the negative electrode 2 are stacked so that the rectangles substantially overlap each other. That is, in FIG. 6, the short side of the positive electrode active material layer 162 and the short side of the negative electrode active material layer 262 are in contact with each other. The positive electrode 1 and the negative electrode 2 are stacked so that they almost overlap. The negative electrode active material uncoated portion 164 of the negative electrode 2 and the negative electrode active material uncoated portion 264 of the negative electrode 2 are located on opposite sides of the rectangle. That is, they are stacked so as to be positioned along the short side of the positive electrode current collector 161 of the positive electrode 1. The positive electrode active material uncoated portion 164 is located along the short side of the negative electrode current collector 261 of the negative electrode 2. The negative electrode active material uncoated portion 264 is overlapped with the negative electrode active material uncoated portion 262 so as to be positioned on the opposing short sides. That is, in FIG. 5, the positive electrode active material uncoated portion 154 of the positive electrode is located on the left side of the drawing. The negative electrode active material uncoated portion 254 of the negative electrode is located on the right side of the drawing.

[0032] In the embodiment, the boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is The uncoated portion is located closer to the periphery of the negative electrode current collector than the periphery of the positive electrode current collector adjacent to the uncoated portion. It is preferable that the boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is The negative electrode active material is located closer to the periphery of the negative electrode current collector than the periphery of the adjacent positive electrode current collector. The boundary between the coated area and the area where the negative electrode active material is not coated (i.e., the edge of the coated area) overlaps the negative electrode. The negative electrode current collector is located closer to the periphery (i.e., the negative electrode current collector) than to the periphery of the positive electrode current collector of the adjacent overlapping positive electrodes. In this specification, the term "adjacent" means that the electrode is located on the outer side of the electrode current collector. refers to two things overlapping so that they are placed next to each other, and not touching. In other words, it is acceptable for two adjacent objects to be sandwiched between other objects. It shall be considered good.

[0033] Furthermore, in the embodiment, the boundary between the flat portion of the negative electrode active material layer and the thin portion of the negative electrode active material layer is The area is located closer to the center of the negative electrode current collector than the peripheral area of ​​the positive electrode current collector adjacent to the area where the active material is not applied. It is preferable that the boundary between the flat portion of the negative electrode active material layer and the thin portion of the negative electrode active material layer is The uncoated portion is located closer to the center of the negative electrode current collector than the peripheral edge of the positive electrode current collector adjacent to the uncoated portion. The boundary between the flat portion of the negative electrode active material layer and the thin portion of the negative electrode active material layer (i.e., the thickness of the negative electrode active material layer) The boundary between the negative electrode and the positive electrode is larger than the periphery of the positive electrode current collector of the adjacent positive electrode. This means that the negative electrode current collector is located closer to the center of the negative electrode current collector (that is, on the inside of the negative electrode current collector).

[0034] Further, in the embodiment, the density of the thin portion of the negative electrode active material layer is greater than the density of the flat portion of the negative electrode active material layer. It is preferable that the density of the thin portion of the negative electrode active material layer is equal to or smaller than that of the negative electrode active material. If there is a difference between the density of the thin part of the negative electrode active material layer and the density of the flat part of the negative electrode active material layer, As mentioned above, the density of the portion is smaller than that of the portion of the substrate. The electrode proposed here has a locally raised shape due to the insulating material attached to the electrode end. To prevent this, a thin, high-density portion is provided on the outer periphery of the active material application area. Generally, metallic lithium is deposited on the negative electrode during the charge and discharge of a lithium-ion secondary battery. To prevent this, the capacity of the negative electrode is made larger than that of the positive electrode. In other words, the area of ​​the negative electrode active material layer is usually larger than that of the positive electrode active material layer. In such a configuration, the starting end of the negative electrode active material layer is inevitably There will be a part of the current collector that is adjacent to the part that is not coated with the positive electrode active material. It is necessary to provide an insulating material to prevent lithium deposition. In order to prevent this, the invention of Patent Document 1 was proposed.

[0035] In Patent Document 1, the negative electrode portion adjacent to and overlapping with the insulating member provided on the positive electrode is not considered to be substantially involved in the operation of the battery, and lithium ions are prevented from entering the relevant part. In addition, a high density portion is provided on the outer periphery of the negative electrode. When the negative electrode is removed, the area of ​​the negative electrode is increased and the battery is no longer involved in the operation of the battery. This would be contrary to the intention of increasing energy density.

[0036] In the embodiment of the present invention, as described above, the density of the thin portion of the negative electrode active material layer is The density of the layer is set to be equal to or smaller than that of the flat part of the layer. When charging a lithium secondary battery, lithium ions move from the positive electrode to the negative electrode and The lithium metal reaches the negative electrode surface and is radiated into the negative electrode active material layer without being deposited on the surface. At this time, lithium ions also spread to the thin part of the negative electrode active material. Therefore, the thin portion of the negative electrode active material also substantially participates in the operation of the battery. The area of ​​the positive electrode active material layer provided on the electrode should not exceed the area of ​​the negative electrode active material layer. In other words, if the starting end of the positive electrode active material layer is The area of ​​the positive electrode active material layer can be increased to the extent that it does not extend beyond the starting end of the layer toward the periphery. In this embodiment, the area of ​​the positive electrode active material layer does not need to be made smaller than necessary. The capacity of a lithium ion secondary battery using this lithium ion secondary battery element can be increased. It becomes possible.

[0037] FIG. 7 shows a first embodiment of a lithium ion secondary battery constructed by stacking a positive electrode and a negative electrode. 7 is a cross-sectional view of the element. In FIG. 7, 1: positive electrode; 2: negative electrode; 3: separator; 171: positive Electrode current collector; 172: Positive electrode active material layer; 173: Positive electrode active material coated portion; 174: Positive electrode active material uncoated Cloth part; 175: Thin part of positive electrode active material layer; 176: Flat part of positive electrode active material layer; 177: Positive electrode current collector Periphery; 271: negative electrode current collector; 272: negative electrode active material layer; 273: negative electrode active material coating portion; 27 4: Uncoated part of negative electrode active material; 275: Thin part of negative electrode active material layer; 276: Flat part of negative electrode active material layer; 277: Boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion; 278: Flat negative electrode active material layer 7, the boundary between the positive electrode 1 and the separator 2 is shown. Although the negative electrode 3 and the negative electrode 2 are shown as being separated from each other, it is easy to understand from the viewpoint of explaining each component. In an actual lithium ion secondary battery element, these components are They are stacked so that they touch each other.

[0038] In FIG. 7, a boundary 277 between a negative electrode active material coated portion 273 and a negative electrode active material uncoated portion 274 is larger than the positive electrode current collector peripheral portion 177 of the positive electrode 1 adjacent to the negative electrode active material uncoated portion 274. , and is located on the peripheral edge side of the negative electrode current collector (on the right side as viewed in FIG. 7). The boundary 278 between the negative electrode active material layer thin portion 275 and the negative electrode active material uncoated portion 274 is adjacent to the boundary 278. The positive electrode 1 is positioned closer to the center of the negative electrode current collector (as viewed from the side of FIG. 7) than to the peripheral edge 177 of the positive electrode current collector. At this time, the density of the negative electrode active material layer thin portion 275 is The density of the negative electrode 2 is equal to or smaller than that of the support portion 276. and are stacked in the above-described positional relationship to form a lithium ion secondary battery element of the first type. do.

[0039] In the lithium ion secondary battery element of the first embodiment, the positive electrode active material uncoated portion The positive electrode 1 and the negative electrode 2 are overlapped in a positional relationship such that the negative electrode active material coating portion is adjacent to the negative electrode active material coating portion. When the positive electrode active material is not applied (see FIG. 10), the insulating layer is formed so as to cover at least a part of the positive electrode active material-unapplied portion. It is preferable to provide a member (1107) between the positive electrode active material uncoated portion and the negative electrode active material coated portion. When the two electrodes are in contact, a short circuit may occur in that area. Therefore, in order to prevent such inconvenience as much as possible, an insulating member is provided. The insulating member may be, for example, an adhesive tape having an adhesive layer on a polyolefin film. This can be achieved by using a filter or by coating it with an insulating material such as alumina. The insulating member is formed after forming the thin portion of the positive electrode active material layer and the flat portion of the positive electrode active material layer as described later. Alternatively, an insulating member may be first placed at a predetermined position on the current collector, and then one of the thin portions of the positive electrode active material layer may be provided. The thin portion of the positive electrode active material layer and the flat portion of the positive electrode active material layer may be formed so that the thin portion covers the insulating member.

[0040] Another embodiment of the present invention will be described. The lithium ion secondary battery element of the second embodiment comprises: A positive electrode active material is applied to at least a portion of both surfaces of the positive electrode current collector in substantially the same shape. The positive electrode current collector is a generally rectangular positive electrode active material layer coated with a positive electrode active material. and a positive electrode active material uncoated portion where the positive electrode active material is not coated, , located along at least a part of the peripheral edge of the positive electrode current collector, and the positive electrode active material layer is The positive electrode active material layer is composed of a thin portion and a flat portion. The coating device has an insulating member that covers at least a portion of the coating portion.

[0041] In the embodiment, the positive electrode is formed by applying or rolling a positive electrode current collector such as a metal foil and drying it. The positive electrode is a thin plate or sheet-like battery component on which an active material layer is formed. The positive electrode active material layer includes a positive electrode active material and is coated on both sides of the positive electrode active material layer. In the fine print, when we say positive electrode active material, we mean the positive electrode active material that is responsible for the conductivity of the battery, the binder, and the necessary In this case, it may mean a mixture with a conductive additive. When viewed from the other side, it is not necessary for the coating to cover the entire surface of the positive electrode current collector. Preferably, the positive electrode current collector is a generally coated positive electrode active material. The cathode active material layer has a rectangular shape, and a cathode active material uncoated portion where the cathode active material is not coated. are.

[0042] In the embodiment, the positive electrode active material is applied in substantially the same shape to two positive electrode current collectors. When the surfaces are viewed from each side, the positive electrode active materials are arranged in substantially the same shape; In addition, when looking at the cross section of the positive electrode, the positive electrode active material has an almost symmetrical shape with the positive electrode current collector as the boundary. It means both that the

[0043] The positive electrode active material layer has a thin portion where the positive electrode active material is thin and a thin portion where the positive electrode active material is almost uniformly distributed. The positive electrode active material layer may be formed by applying a positive electrode active material layer having a flat portion to a uniform thickness. The thin portion and the flat portion of the positive electrode active material layer may be located anywhere in the positive electrode active material layer. For example, the thin portion of the positive electrode active material layer can be located at the periphery of the positive electrode active material layer. The thickness of the positive electrode active material layer gradually decreases toward the boundary between the material-coated portion and the positive electrode active material-uncoated portion. That is, the thin portion of the positive electrode active material layer may be a portion where the positive electrode active material is not applied and the positive electrode active material is not applied. The thickness of the positive electrode active material layer is gradually reduced toward the boundary with the coating area. The shape of the positive electrode active material layer is generally rectangular. Here, "generally rectangular" means When the two surfaces of the positive electrode current collector are viewed from each side, the shape of the positive electrode active material layer is a quadrilateral (rectangular). This means that the shape is a polygon (e.g., a triangle, square, rhombus, parallelogram, etc.).

[0044] In the embodiment, an insulating member is provided so as to cover at least a part of the positive electrode active material uncoated portion. When a portion where the positive electrode active material is not applied is adjacent to a portion where the negative electrode active material is applied, A short circuit may occur in the area, which may increase the amount of heat generated in the area. In order to prevent such inconvenience as much as possible, an insulating member may be provided. For example, adhesive tape with an adhesive layer on a polyolefin film can be used. Cut.

[0045] The lithium ion secondary battery element of the embodiment has a structure in which the negative electrode current collector is provided with a substantially identical shape on both sides thereof. The negative electrode includes a negative electrode having a negative electrode active material applied to at least a portion of both surfaces. The negative electrode active material layer is generally rectangular and has substantially the same shape as the positive electrode active material layer. a negative electrode active material uncoated portion where the negative electrode active material is not coated, The portion is located along at least a part of the peripheral edge of the negative electrode current collector, and further includes a negative electrode active material layer is composed of a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer.

[0046] In the embodiment, the negative electrode is formed by applying or rolling a negative electrode current collector such as a metal foil and then drying it. The negative electrode is a thin plate or sheet-like battery component on which an active material layer is formed. The negative electrode active material layer includes a negative electrode active material and is coated on both sides of the negative electrode active material layer. In the fine print, when we say negative electrode active material, we mean the negative electrode active material that is responsible for the conductivity of the battery, the binder, and the necessary In this case, it may mean a mixture with a conductive additive. When viewed from the negative electrode current collector side, it is not necessary for the coating to cover the entire surface of the negative electrode current collector. Preferably, the negative electrode current collector is a substantially solid negative electrode current collector coated with the negative electrode active material. The negative electrode active material layer has a rectangular shape, and a negative electrode active material uncoated portion where the negative electrode active material is not coated. are.

[0047] In the embodiment, the negative electrode active material is applied in substantially the same shape to two negative electrode current collectors. When the surface is viewed from each side, the negative electrode active material is arranged in substantially the same shape; In addition, when looking at the cross section of the negative electrode, the negative electrode active material has an almost symmetrical shape with the negative electrode current collector as the boundary. It means both that the

[0048] The negative electrode active material layer has a thin portion where the negative electrode active material is thin and a thin portion where the negative electrode active material is almost uniformly distributed. The negative electrode active material layer may be formed by applying a flat portion of the negative electrode active material layer to a uniform thickness. The thin portion and the flat portion of the negative electrode active material layer may be located anywhere in the negative electrode active material layer. For example, the thin portion of the negative electrode active material layer can be located at the periphery of the negative electrode active material layer. The thickness of the negative electrode active material layer gradually decreases toward the boundary between the material-coated portion and the negative electrode active material-uncoated portion. That is, the thin portion of the negative electrode active material layer may be a portion between the negative electrode active material coated portion and the negative electrode active material uncoated portion. The thickness of the negative electrode active material layer is gradually reduced toward the boundary with the coating area. The negative electrode active material layer may have a generally rectangular shape. When the two surfaces of the negative electrode current collector are viewed from each side, the shape of the negative electrode active material layer is a quadrilateral (rectangular). This means that the shape is a polygon (e.g., a triangle, square, rhombus, parallelogram, etc.).

[0049] The lithium ion secondary battery element of the embodiment has the generally rectangular positive electrode active material layer of the positive electrode and The generally rectangular negative electrode active material layer of the negative electrode is placed on the positive electrode so that the rectangles are almost overlapping each other. The positive electrode has a generally rectangular positive electrode active material layer and the negative electrode has a generally rectangular positive electrode active material layer. The positive electrode and the negative electrode are stacked so that the rectangular shapes of the negative electrode active material layer and the rectangular shapes of the negative electrode active material layer are almost overlapping each other. In the example, each side of the generally rectangular positive electrode active material layer and each side of the generally rectangular negative electrode active material layer are approximately For example, the positive electrode active material layer When the shape is rectangular, the shape of the negative electrode active material layer is approximately the same rectangle, and the shape of the positive electrode active material layer is approximately the same rectangle. The positive and negative electrodes are arranged so that the long sides of the rectangular active material layer and the long sides of the negative electrode active material layer are roughly overlapping each other. Here, the shape of the positive electrode active material layer and the shape of the negative electrode active material layer may be slightly different. It is not necessary that the layers are exactly the same, and the positive electrode active material layer and the negative electrode active material layer are exactly overlapped without any difference. There is no need to stack the positive and negative electrodes so that the rectangular shape of the positive electrode active material layer and the rectangular shape of the negative electrode active material layer are The shapes need only be roughly the same, and the two need only roughly overlap.

[0050] In this embodiment, the positive electrode active material uncoated portion of the positive electrode and the negative electrode active material uncoated portion of the negative electrode are: It is preferable that the positive electrode and the negative electrode are stacked on top of each other so as to be located on the same side of a rectangle. The positive electrode active material uncoated portion and the negative electrode active material uncoated portion are positioned on the same side of the rectangle. The phrase "overlap the negative electrode" means that, for example, the positive electrode active material uncoated portion is aligned with the rectangular shape of the positive electrode active material layer. When the negative electrode active material uncoated portion is located on the short side, the negative electrode active material uncoated portion is located on the same short side of the rectangle of the negative electrode active material layer. This means that the device is located at the position indicated in the figure.

[0051] In this embodiment, when the positive electrode and the negative electrode are stacked, A separator may also be disposed.

[0052] In the embodiment, the boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is made of an insulating member. It is preferable that the negative electrode active material coated portion and the negative electrode active material uncoated portion are positioned adjacent to each other. The boundary between the negative electrode active material coating portion and the insulating member is located adjacent to the insulating member. The boundary between the negative electrode active material-uncoated portion (i.e., the edge of the negative electrode active material-coated portion) is adjacent to the portion. The insulating member is arranged to overlap with the insulating member that covers at least a part of the positive electrode active material uncoated portion. This means that there is

[0053] In the embodiment, the boundary between the thin portion of the negative electrode active material layer and the flat portion of the negative electrode active material layer is It is preferable that the thin portion of the negative electrode active material layer and the flat portion of the negative electrode active material layer are adjacent to each other. The boundary portion with the flat portion of the material layer is located adjacent to the flat portion of the positive electrode active material layer. The boundary between the thin part of the electrode active material layer and the flat part of the negative electrode active material layer (i.e., the area where the thickness of the negative electrode active material layer changes) The positive electrode active material layer is placed so that the boundary between the positive electrode and the flat portion of the positive electrode active material layer overlaps with the flat portion of the positive electrode active material layer. It means that it is placed.

[0054] Further, in the embodiment, the density of the thin portion of the negative electrode active material layer is greater than the density of the flat portion of the negative electrode active material layer. It is preferable that the density of the thin portion of the negative electrode active material layer is equal to or smaller than that of the negative electrode active material. If there is a difference between the density of the thin part of the negative electrode active material layer and the density of the flat part of the negative electrode active material layer, The density of the part is smaller.

[0055] In the second embodiment, a positive electrode having a shape shown in FIGS. 1 and 2 can be used, and a positive electrode having a shape shown in FIG. 3 can be used. 4. A negative electrode having the shape shown in FIG.

[0056] FIG. 8 shows a lithium ion battery according to a second embodiment, which is constructed by stacking the positive electrode and the negative electrode. 8 is a cross-sectional view of a secondary battery element, in which 1: positive electrode; 2: negative electrode; 3: separator; 181: positive electrode current collector; 182: positive electrode active material layer; 183: positive electrode active material coating portion; 184: positive electrode Active material uncoated portion; 185: thin portion of positive electrode active material layer; 186: flat portion of positive electrode active material layer; 187: Insulating member; 281: negative electrode current collector; 282: negative electrode active material layer; 283: negative electrode active material coating portion; 2 84: Uncoated part of negative electrode active material; 285: Thin part of negative electrode active material layer; 286: Flat part of negative electrode active material layer In FIG. 8, the positive electrode 1, the separator 3, and the negative electrode 2 are separated from each other. However, this is written in an easy-to-understand manner to explain each component. In the lithium-ion secondary battery element, these components are stacked so that they are in contact with each other. On the other hand, FIG. 9 is a plan view of the lithium ion secondary battery element of FIG. 8 as seen from the direction A (FIG. 9a) and a plan view from the direction B (Fig. 9b). In Fig. 9, 1: positive electrode; 2: negative electrode 191: positive electrode current collector; 192: positive electrode active material layer; 194: positive electrode active material uncoated portion; 197: Insulating member; 291: negative electrode current collector; 292: negative electrode active material layer; 294: negative electrode active material uncoated portion be.

[0057] First, in FIG. 9(a), the positive electrode active material uncoated portion 194 of the positive electrode is formed by a rectangular positive electrode current collector 1. 9(b), the negative electrode is positioned along the short side of the negative electrode active material uncoated. The fabric portion 294 is also positioned along the short side of the rectangular negative electrode current collector 291. The electrode active material uncoated portion 194 and the negative electrode active material uncoated portion 294 are arranged along the same side of the rectangle (see FIG. The positive electrode and the negative electrode are stacked so that they are positioned on the left side of the stack (9a).

[0058] In FIG. 8, as described above, the positive electrode active material uncoated portion 184 of the positive electrode is on the left side as viewed in FIG. 8, and the negative electrode active material uncoated portion 284 of the negative electrode is also located on the left side as viewed in FIG. The boundary 287 between the negative electrode active material coated portion and the negative electrode active material uncoated portion (i.e., the negative electrode active material uncoated portion) The end of the thin portion of the negative electrode active material layer is positioned adjacent to the insulating member 187. and the flat portion of the negative electrode active material layer (i.e., the boundary where the thickness of the negative electrode active material layer changes). The flat portion 183 of the positive electrode active material layer is located adjacent to the flat portion 183 of the positive electrode active material layer. The density of the thin portion 285 of the electrode active material layer is equal to or greater than the density of the flat portion 286 of the negative electrode active material layer. The negative electrode 2 is placed on the positive electrode 1 in the above-mentioned positional relationship. This constitutes a lithium ion secondary battery element of the second embodiment.

[0059] A lithium ion secondary battery is manufactured using the lithium ion secondary battery element of each of the above embodiments. Another embodiment of the present invention is a lithium ion battery according to any of the above embodiments. A lithium ion secondary battery device, which includes a power generating element including an ion secondary battery element and an electrolyte solution inside an exterior body, It is a secondary battery.

[0060] Here, the lithium ion secondary battery element and the lithium ion secondary battery element of all the embodiments The components constituting the battery will be described in detail. The positive electrode is a positive electrode coated with a positive electrode active material. The positive electrode comprises a positive electrode active material, a binder, and in some cases The positive electrode active material mixture containing the conductive additive is coated on a positive electrode current collector made of a metal foil such as aluminum foil. The positive electrode active material layer is formed by rolling or by drying. The positive electrode active material layer contains pores. It is preferably in a porous or microporous form. The material layer preferably contains a lithium-nickel composite oxide as a positive electrode active material. Li-nickel composite oxides are compounds with the general formula Li x Ni y Me (1-y) O2 (where Me is , Al, Mn, Na, Fe, Co, Cr, Cu, Zn, Ca, K, Mg, and Pb At least one metal selected from the group consisting of lithium and nickel. It is a transition metal composite oxide containing nickel.

[0061] The positive electrode active material layer may contain a lithium-manganese composite oxide as the positive electrode active material. Lithium-manganese composite oxides include, for example, lithium manganate with a zigzag layer structure. Lithium manganese oxide (LiMnO2), spinel type lithium manganese oxide (LiMn2O4), etc. By using lithium-manganese composite oxides in combination, it is possible to produce a positive electrode more cheaply. In particular, spinel-type manganese oxide, which has excellent crystal structure stability in an overcharged state, can be used. It is preferable to use lithium manganese oxide (LiMn2O4). When an active material is contained, it is preferably contained in an amount of 70% by weight or less based on the weight of the positive electrode active material, and It is more preferable that the content of the positive electrode active material is 0% by weight or less. If the amount of lithium-manganese composite oxide contained is too high, it may cause metal foreign matter to be mixed into the battery. A partial cell is easily formed between the deposits derived from the material and the mixed positive electrode, and short-circuit current easily flows. It becomes.

[0062] The positive electrode active material layer is particularly a compound represented by the general formula Li x Ni y Co z Mn (1-y-z) Represented by O2 A lithium nickel manganese cobalt composite oxide with a layered crystal structure is used as the positive electrode active material. In the general formula, x is 1≦x≦1.2, and y and z are y+ It is a positive number that satisfies z<1, and the value of y is 0.5 or more. If the value is too large, it becomes difficult to synthesize a single-phase composite oxide. Therefore, 1-yz≦0.4 should be set. In order to obtain a high capacity battery, it is particularly preferable that y>1-yz, y>z. The lithium-nickel composite oxide having this general formula is preferably Nickel-cobalt-manganese composite oxide (hereinafter referred to as "NCM") NCM is a lithium-nickel composite that is suitable for increasing the capacity of batteries. For example, the general formula Li x Ni y Co z Mn (1.0-y-z) O2 smell The composite oxide with x=1, y=0.8, and z=0.1 is called "NCM811" and the composite oxide with x=1, y=0.8, and z=0.1 is called "NCM811". The composite oxide with y=0.5 and z=0.2 is called "NCM523."

[0063] The binders used in the positive electrode active material layer are polyvinylidene fluoride (PVDF), poly Fluorine resins such as tetrafluoroethylene (PTFE) and polyvinyl fluoride (PVF), Conductive polymers such as lyanilines, polythiophenes, polyacetylenes, and polypyrroles Styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber bar (CR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR ), or synthetic rubber such as carboxymethyl cellulose (CMC), xanthan gum, Polysaccharides such as argum and pectin can be used.

[0064] As a conductive additive that may be used in the positive electrode active material layer, carbon nanofibers or the like may be used. Carbon fiber, acetylene black, ketjen black, activated carbon, Examples include carbon materials such as graphite, mesoporous carbon, fullerenes, and carbon nanotubes. In addition, the positive electrode active material layer contains other additives for forming the electrode, such as a thickener, a dispersant, and a stabilizer. Any commonly used electrode additive can be used as appropriate.

[0065] As described above, the positive electrode active material layer may have an uncoated portion where the positive electrode active material is not coated. The portion of the positive electrode current collector on which the positive electrode active material is not applied is provided particularly for connecting a positive electrode lead. The positive electrode active material layer may be provided with a uniform thickness, or the thickness may be varied depending on the application location. The positive electrode active material layer is formed toward the boundary between the positive electrode active material coated portion and the positive electrode active material uncoated portion. The positive electrode active material layer has a thin portion where the thickness thereof is reduced, and a flat portion where the positive electrode active material layer is flat. In some cases, the thin portion of the positive electrode active material layer thus provided may an insulating member is provided so as to cover at least a part of the positive electrode active material uncoated portion and at least a part of the positive electrode active material uncoated portion; The positive electrode active material uncoated portion may be adjacent to the negative electrode active material coated portion. In the case where the lithium ion secondary battery element is used (for example, in the case of the lithium ion secondary battery element of the second embodiment), A short circuit may occur in the area, which may increase the amount of heat generated in the area. In order to prevent such inconvenience as much as possible, an insulating member may be provided. For example, an adhesive tape having an adhesive layer on a polyolefin film can be used.

[0066] The negative electrode that can be used in all embodiments is a negative electrode coated with a negative electrode active material mixture. The negative electrode is a mixture of a negative electrode active material, a binder, and optionally a conductive additive. The negative electrode active material is obtained by applying or rolling the material onto a negative electrode current collector made of a metal foil such as copper foil, and then drying it. The negative electrode active material layer has a porous or microporous shape containing pores. In each embodiment, it is preferable that the negative electrode active material contains graphite. The inclusion of graphite improves the battery's output even when the battery's State of Charge (SOC) is low. Graphite is a carbon material with hexagonal plate-shaped crystals, and graphite , graphite, etc. The graphite is preferably in the form of particles.

[0067] There are two types of graphite: natural graphite and artificial graphite. Natural graphite is cheap and can be obtained in large quantities. It has a stable structure and excellent durability. Artificial graphite is graphite that is artificially produced. It has low electrical resistance due to its high purity (it contains almost no impurities such as allotropes). In the present embodiment, both natural graphite and artificial graphite can be suitably used as the carbon material. Natural graphite coated with amorphous carbon or artificial graphite coated with amorphous carbon can also be used.

[0068] Amorphous carbon is a material that may have a structure similar to that of graphite in part, but is composed of fine crystals. It is a carbon material that has a random network structure and is amorphous overall. Amorphous carbon includes carbon black, coke, activated carbon, carbon fiber, and hard carbon. Examples of such carbon include hard carbon, soft carbon, and mesoporous carbon.

[0069] These negative electrode active materials may be used in combination as needed. A mixed carbon material containing both graphite particles and amorphous carbon particles can also be used. When used as a negative electrode active material, it improves the regenerative performance of the battery. Natural graphite particles or artificial graphite coated with amorphous carbon are used as the carbon material for the negative electrode active material. When used as such, decomposition of the electrolyte is suppressed, and the durability of the negative electrode is improved.

[0070] When using artificial graphite, the interlayer distance d value (d 002 ) is 0.337 nm or more The crystal structure of artificial graphite is generally thinner than that of natural graphite. When used as a negative electrode active material for lithium ion secondary batteries, the layer into which lithium ions can be inserted is The interlayer distance that allows lithium ions to be inserted and removed is the d value ( d 002 ) and if the d value is 0.337 nm or more, there is no problem with lithium Ion insertion and desorption occurs.

[0071] As the negative electrode active material, any material that can occlude and release lithium ions can be used without particular limitation, and known materials can be used. Specific examples of the negative electrode active material include carbon materials such as graphite (natural graphite, artificial graphite, etc.), coke, and hard carbon as described above In addition, lithium alloys such as lithium-aluminum alloy, lithium-lead alloy, and lithium-tin alloy, lithium metal, Si, SnO2, SnO, TiO2, SiO, Li4Ti5O 12 and other metal oxides with a lower potential than the positive electrode active material can be mentioned. These can be used alone or in combination of two or more.

[0072] Among them, metals that form alloys with Li such as Li metal, Si, Sn, Al, etc., and silicon oxides (SiO x (0 < x ≦ 2)), Si composite oxides containing Si and other metal elements other than Si (for example, Li, B, Mg [[ID=reg]]Na, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, etc.), Sn oxides, Sn composite oxides containing Sn and other metal elements other than Sn, etc. By combining a negative electrode active material containing a metal oxide capable of occluding and releasing lithium ions with the positive electrode according to the present invention described above, a greater effect of improving the energy density can be obtained. These negative electrode active materials may form a composite with a carbon material. Further, they may be coated with a carbon material. The content of these negative electrode active materials is not particularly limited, but from the viewpoint of increasing the energy density, it is generally 5% by weight or more in the negative electrode active material, preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 40% by weight or more.

[0073] As the binder used for the negative electrode active material layer, polyvinylidene fluoride (PVDF), poly ​​​​​​​​Fluorine resins such as tetrafluoroethylene (PTFE) and polyvinyl fluoride (PVF), Conductive polymers such as lyanilines, polythiophenes, polyacetylenes, and polypyrroles Styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber bar (CR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR ), or synthetic rubber such as carboxymethyl cellulose (CMC), xanthan gum, Polysaccharides such as argum and pectin can be used.

[0074] As a conductive additive that may be used in the negative electrode active material layer, carbon nanofibers or the like may be used. Carbon fiber, acetylene black, ketjen black, activated carbon, Examples include carbon materials such as mesoporous carbon, fullerenes, and carbon nanotubes. In addition, the negative electrode active material layer contains thickeners, dispersants, stabilizers, and other additives that are generally used in electrode formation. Any electrode additives that can be used can be used as appropriate.

[0075] As described above, the negative electrode active material layer may have an uncoated portion where the negative electrode active material is not coated. The portion of the negative electrode current collector on which the negative electrode active material is not applied is provided particularly for connecting the negative electrode lead. The thickness of the negative electrode active material layer can be changed depending on the application location. The thickness of the negative electrode active material layer is smaller toward the boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion. The negative electrode active material layer may have a thin portion where the negative electrode active material layer is thinned and a flat portion where the negative electrode active material layer is flat.

[0076] The positive and negative electrodes that can be used in all embodiments are the positive electrodes described above. An electrode active material layer containing an active material or a negative electrode active material is disposed on an electrode current collector. In this case, the thickness of the flat portion of each electrode active material layer is 10 to 100 μm per side. The thickness of the flat portion of each electrode active material layer is preferably 50 to 80 μm. If the thickness is too small, it is difficult to form a uniform electrode active material layer. If the thickness of the flat portion of the active material layer is too large, the charge / discharge performance at high rates will be reduced. It is possible that the thickness of the negative electrode active material layer is greater than the thickness of the separator over the entire surface of the negative electrode active material layer. It is preferable that the thickness of each positive electrode active material layer is larger than the thickness of the adjacent positive electrode active material layer therebetween.

[0077] In all the embodiments of the lithium ion secondary battery element, a separator may be used in some cases. The separator can be made of, for example, a polyolefin film. Polyolefins are polymers of ethylene, propylene, butene, pentene, hexene, etc. It is a compound obtained by polymerizing or copolymerizing α-olefins, such as polyolefins. Ethylene, polypropylene, polybutene, polypentene, polyhexene, and other When a polyolefin film is used as the separator, The structure has pores that are closed when the battery temperature rises, i.e., porous or microporous polymers. It is advantageous if the polyolefin film has such a structure. By having this, even if the battery temperature rises, the separator will close (shut down) down), which can disrupt the ion flow. When the battery is heated, the film shrinks and closes the holes, preventing short circuits between the positive and negative electrodes. To achieve the shutdown effect, it is essential to use a porous polyethylene film. Always preferable.

[0078] Also, crosslinked films can be used as separators. Since the polyolefin film has the property of shrinking when heated, the film may shrink when the battery becomes overheated. However, if the film's thermal shrinkage rate is too large, The area of ​​the film will change significantly, which may result in a large current flow. Cross-linked polyolefin film has an appropriate heat shrinkage rate, so it does not shrink when overheated. Even if the surface area is large, the film can shrink by the amount required to close the holes without causing a large change in area.

[0079] The separator used in all embodiments has a surface on one or both sides of the separator. The battery may have a heat-resistant fine particle layer. The thermal particle layer is made of inorganic particles that are heat-resistant to temperatures of 150°C or higher and stable in electrochemical reactions. Such inorganic particles include silica, alumina (α-alumina, β-alumina, θ-alumina), iron oxide, titanium oxide, barium titanate, zirconium oxide Inorganic oxides such as aluminum; boehmite, zeolite, apatite, kaolin, spinel, magnesium Examples of minerals include quartz and mullite.

[0080] The positive electrode, separator, and negative electrode are all in the form of independent sheets. When stacking separators, place them between the positive and negative electrodes. In this way, a lithium ion secondary battery element can be formed.

[0081] Such a lithium ion secondary battery element is immersed in an electrolyte solution and further sealed with an exterior body. This allows the formation of a lithium-ion battery. The battery element is wrapped in a relatively flexible exterior material so that at least a part of the battery element is not exposed to the outside air. The exterior of the lithium ion secondary battery has gas barrier properties and The housing is made of a flexible material that can seal the lithium-ion secondary battery element. The outer packaging is made of aluminum cans or aluminum foil and polypropylene. An aluminum laminate sheet laminated with propylene or the like can be suitably used. Lithium-ion secondary batteries come in various types, including coin-type batteries, laminated batteries, and wound batteries. It may be in the form of:

[0082] An electrolyte is an electrically conductive solution in which ionic substances are dissolved in a solvent. In all embodiments, a non-aqueous electrolyte solution can be used. A lithium ion secondary battery containing an electrolyte is placed on the battery, and a separator is optionally placed on the battery. A battery element is a unit of the main components of a battery. Usually, a plurality of positive electrodes and a plurality of negative electrodes are connected to each other. The laminate formed by stacking the above-mentioned electrodes with a separator interposed therebetween is immersed in an electrolyte solution. The electrolyte that can be used in all the embodiments is a non-aqueous electrolyte, diethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate EMC, di-n-propyl carbonate, di-t-propyl carbonate, di-n -butyl carbonate, di-isobutyl carbonate, or di-t-butyl carbonate Chain carbonates such as propylene carbonate (PC), ethylene carbonate ( The electrolyte is preferably a mixture containing a cyclic carbonate such as ethylenediaminetetraacetic acid (EC). A mixture of various carbonates, lithium hexafluorophosphate (LiPF6), and lithium fluoroborate (LiBF4), lithium perchlorate (LiClO4), etc. be.

[0083] The electrolyte may also contain, as an additive, a cyclic carbonate other than the above-mentioned cyclic carbonate. The cyclic carbonate used as an additive may contain vinylene compounds. Carbonate (VC) is one of the additives. These cyclic carbonates also act as positive electrodes during the charge and discharge process of the battery. It is a compound that forms a protective coating on the electrode and the negative electrode. or sulfur-containing compounds such as disulfonate compounds, It is a compound that can prevent attack on the positive electrode active material containing the halogen-based composite oxide. Examples of cyclic carbonate compounds having the formula include fluoroethylene carbonate (FEC), diethylene carbonate (DEC), and Fluoroethylene carbonate, trifluoroethylene carbonate, chloroethylene carbonate Carbonate, dichloroethylene carbonate, trichloroethylene carbonate, etc. It is possible to use a cyclic carbonate compound having a halogen and an unsaturated bond. Oxyethylene carbonate is particularly preferably used.

[0084] The electrolyte may further contain a disulfonic acid compound as an additive. A sulfonic acid compound is a compound that has two sulfo groups in one molecule, and the sulfo groups are bonded to metal ions. Disulfonate compounds that form salts with sulfonates, or disulfonates in which the sulfo groups form esters It includes sulfonate ester compounds. One or two of the sulfo groups of disulfonic acid compounds may form a salt with a metal ion or may be in an anionic state. Examples of sulfonic acid compounds include methanedisulfonic acid, 1,2-ethanedisulfonic acid, and 1,3- Propanedisulfonic acid, 1,4-butanedisulfonic acid, benzenedisulfonic acid, naphthalene disulfonic acid, biphenyl disulfonic acid, and their salts (lithium methane disulfonate) ammonium, lithium 1,2-ethanedisulfonate, etc.), and their anions (methanedisulfonate, Examples of the anion include disulfonate anion, 1,2-ethanedisulfonate anion, etc. Examples of sulfonic acid compounds include disulfonic acid ester compounds, such as methane disulfonic acid, 1 ,2-ethanedisulfonic acid, 1,3-propanedisulfonic acid, 1,4-butanedisulfone acid, benzenedisulfonic acid, naphthalenedisulfonic acid, or biphenyldisulfonic acid Acyclic disulfonic acid esters such as alkyl diesters or aryl diesters; and Methylenemethane disulfonate, ethylene methane disulfonate, propylene Cyclic disulfonic acid esters such as methane disulfonic acid esters are preferably used. Ethylenemethane disulfonic acid ester (MMDS) is particularly preferably used.

[0085] The positive electrode and the negative electrode are stacked with a separator interposed therebetween, and the resulting mixture is mixed with the electrolyte. The lithium ion secondary battery can be formed by enclosing the battery in an exterior body. Any material may be used as long as it does not allow the electrolyte to leak out. The innermost layer is a heat-resistant protective layer made of polyester, polyamide, liquid crystal polymer, etc. Acid-modified polyethylene, polypropylene, ionomer, maleic acid-modified polyethylene, etc. acid-modified polypropylene such as maleic acid-modified polypropylene, polyethylene Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene terephthalate (PEN) Soft phthalate (PEI), PET and PEN blend, PET and PEI blend, Poly Amide resin, blend of polyamide resin and PET, xylylene-containing polyamide and PET A laminate film having a sealant layer made of a thermoplastic resin such as a blend of The exterior body can be made of one or more of these laminate films. It may also be formed by combining and bonding or welding multiple sheets together to form a multilayer structure. The barrier metal layer can be made of aluminum, tin, copper, nickel, or stainless steel. The thickness of the metal layer is preferably 30 to 50 μm. Aluminum foil is a laminate of aluminum foil and polymers such as polyethylene and polypropylene. A laminate can be used.

[0086] Next, a method for manufacturing the lithium ion secondary battery element according to the first embodiment of the present invention will be described. The method for manufacturing a lithium ion secondary battery element is to form a cathode current collector with substantially the same shape on both sides of the cathode current collector. A positive electrode having a positive electrode active material applied to at least a portion of its surface, and a negative electrode current collector having a substantially identical shape on both sides thereof. and a negative electrode having a negative electrode active material applied to at least a portion of both surfaces thereof, A method for manufacturing a lithium ion secondary battery element. The manufacturing method includes first applying a positive electrode active material-containing slurry containing a positive electrode active material and a solvent to a positive electrode current collector. The positive electrode active material is continuously applied in one predetermined direction from a part of the positive electrode active material coated portion and a part not coated with the positive electrode active material. Here, the positive electrode active material coated portion is generally rectangular, and the positive electrode active material uncoated portion is The positive electrode active material coating portion is then positioned along at least a portion of the periphery of the current collector. The entire assembly is uniformly pressed at a predetermined pressure to separate the thin portion of the positive electrode active material layer from the flat portion of the positive electrode active material layer. and are simultaneously formed to obtain a positive electrode. Next, a negative electrode active material-containing slurry containing a negative electrode active material and a solvent is removed from a portion of the negative electrode current collector. The negative electrode active material is continuously applied in one direction to provide a negative electrode active material-coated portion and a negative electrode active material-uncoated portion. The negative electrode active material coated portion is generally rectangular in shape, which is approximately the same as the positive electrode active material coated portion. The uncoated portion is positioned along at least a portion of the periphery of the positive electrode current collector. Then, the entire negative electrode active material coated portion is uniformly pressed with a predetermined pressure to form the thin negative electrode active material layer portion. and the flat portion of the negative electrode active material layer are simultaneously formed, and the density of the thin portion of the negative electrode active material layer is A negative electrode having a density equal to or less than that of the substrate is obtained. Next, the generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode are bonded to each other. The positive electrode and the negative electrode are stacked so that they are almost overlapping each other. The active material uncoated portion and the negative electrode active material uncoated portion of the negative electrode are located on opposite sides of the rectangle, and the negative electrode active material is The boundary between the material-coated portion and the negative electrode active material-uncoated portion is the positive electrode current collector adjacent to the negative electrode active material-uncoated portion. The negative electrode active material layer flat portion and the negative electrode active material layer thin portion are located closer to the peripheral edge of the negative electrode current collector than the peripheral edge of the negative electrode current collector. The boundary between the negative electrode active material-free area and the positive electrode current collector is closer to the negative electrode current collector than the peripheral edge of the positive electrode current collector adjacent to the negative electrode active material-free area. The positive electrode and the negative electrode are overlapped so that they are positioned at the center. The lithium ion secondary battery element of the first embodiment is manufactured by carrying out at least the above steps. When the positive electrode and the negative electrode are stacked, A separator may be disposed between them.

[0087] The method for producing a lithium ion secondary battery element first includes a step of obtaining a positive electrode. Active material (as mentioned above, a positive electrode active material and a positive electrode containing a binder and a conductive additive, etc., if necessary) A positive electrode active material-containing slurry is obtained, which contains the positive electrode active material (which may be a positive electrode active material mixture) and a solvent. The solvent is an organic solvent capable of dispersing the positive electrode active material, such as N-methylpyrrolidone. The obtained positive electrode active material-containing slurry is applied to one side of the positive electrode current collector. The slurry is applied continuously from the top of the surface toward a predetermined direction. Using a machine such as a bar coater that can coat the positive electrode active material on the surface of the positive electrode current collector, At this time, a part of the positive electrode current collector, for example, a generally rectangular positive electrode current collector, is coated with the slurry. When using a rectangular plate, the positive electrode active material-containing slurry is poured into a portion slightly inside the center from one side of the rectangle. The coating can be started and continued in the direction of the opposite side. The positive electrode active material coating portion is generally rectangular, and the positive electrode active material is positioned along one side of the positive electrode current collector. At this time, the positive electrode active material-containing slurry is applied to the surface of the substrate. The amount of the positive electrode active material-containing slurry applied to the other portions is usually slightly less. Next, the entire area where the positive electrode active material is applied is pressed uniformly at a predetermined pressure. Thereafter, if necessary, it is dried to form a thin layer of the positive electrode active material having a slightly smaller amount of the positive electrode active material applied. The positive electrode active material layer has a flat portion and a positive electrode active material layer flat portion on which the positive electrode active material is applied almost uniformly.

[0088] Next, there is a process for obtaining a negative electrode. First, a negative electrode active material (as described above, a negative electrode active material mixture containing a binder and a conductive additive, etc., In this case, the solvent is used to disperse the negative electrode active material. An organic solvent that can be used is, for example, N-methylpyrrolidone. The negative electrode active material-containing slurry is continuously applied from a part of the negative electrode current collector in one predetermined direction. Preferably, a machine such as a bar coater capable of applying the slurry onto a flat surface is used. The negative electrode active material-containing slurry is applied to the flat surface of the negative electrode current collector. For example, when a generally rectangular negative electrode current collector is used, the negative electrode current collector is located slightly from the center of one side of the rectangle. The application of the negative electrode active material slurry begins from the center of the electrode, and then spreads toward the opposite side. In this way, a generally rectangular negative electrode active material coated portion and A negative electrode active material uncoated portion is provided along one side of the negative electrode current collector. The amount of the slurry applied at the application start end of the slurry containing the inorganic substance is usually slightly less, The other portions are coated with the same amount of negative electrode active material-containing slurry. The entire coated area is pressed uniformly at a predetermined pressure. The negative electrode active material layer had a thin portion where the amount of applied active material was slightly less, and the negative electrode active material was applied almost uniformly. The flat portion of the negative electrode active material layer is formed at the same time. The pressure applied to the starting point of the application of the negative electrode active material-containing slurry is smaller than the pressure applied to other parts. Therefore, the thickness of the thin portion of the negative electrode active material layer where the amount of the negative electrode active material applied is slightly smaller than that of the thin portion of the negative electrode active material layer. The density is the same as or less than the density of the flat part of the negative electrode active material layer where the negative electrode active material is applied almost uniformly. It should be noted that other methods, such as coating a positive electrode active material-containing slurry onto a positive electrode current collector, may be used. In addition, even if the method involves applying a slurry containing a negative electrode active material to a negative electrode current collector, each embodiment of the present invention is Any method can be applied as long as it can obtain the positive electrode and negative electrode used in the embodiment.

[0089] The positive electrode and negative electrode thus obtained were stacked together to form a lithium ion secondary battery element. When the positive electrode and the negative electrode are stacked, the generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode are stacked. The positive electrode and the negative electrode are stacked so that the rectangular negative electrode active material layer and the rectangular negative electrode active material layer are almost overlapping each other. Putting the positive and negative electrodes together so that the rectangles are almost overlapping with each other generally means The rectangular positive electrode active material layer and the generally rectangular negative electrode active material layer are arranged so that their sides roughly overlap each other. For example, if the shape of the positive electrode active material layer is When the negative electrode active material layer has a rectangular shape, the negative electrode active material layer has a substantially rectangular shape. The positive electrode and the negative electrode are stacked so that the long sides of the rectangle and the long sides of the negative electrode active material layer are roughly overlapped with each other. Here, the shape of the positive electrode active material layer and the shape of the negative electrode active material layer are exactly the same. The positive and negative electrodes do not need to be aligned so that the positive and negative electrode active material layers overlap exactly. The rectangular shape of the positive electrode active material layer and the rectangular shape of the negative electrode active material layer are roughly the same. It is sufficient that they have the same shape and that they roughly overlap.

[0090] At this time, the positive electrode active material uncoated portion and the negative electrode active material uncoated portion were arranged in a rectangular shape facing each other. The boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is located on the side where the negative electrode active material is uncoated. The negative electrode active material layer is located closer to the periphery of the negative electrode current collector than the periphery of the positive electrode current collector adjacent to the fabric portion. The boundary between the uncoated portion and the thin portion of the negative electrode active material layer is the periphery of the positive electrode current collector adjacent to the portion not coated with the negative electrode active material. The positive and negative electrodes are overlapped so that the positive electrode is positioned closer to the center of the negative electrode current collector than the negative electrode. The positive electrode and the negative electrode can be arranged in a positional relationship as shown in FIG.

[0091] Next, a method for manufacturing a lithium ion secondary battery element according to a second embodiment of the present invention will be described. In the method for manufacturing the lithium ion secondary battery element of the second embodiment, substantially the same thickness is applied to both sides of the positive electrode current collector. A positive electrode having a shape in which a positive electrode active material is applied to at least a part of both sides thereof, and a negative electrode current collector and a negative electrode having substantially the same shape and having a negative electrode active material applied to at least a portion of both surfaces of the negative electrode. This is a method for manufacturing a lithium ion secondary battery element by stacking the electrodes. The manufacturing method includes first applying a positive electrode active material-containing slurry containing a positive electrode active material and a solvent to a positive electrode current collector. The positive electrode active material is continuously applied in one predetermined direction from a part of the positive electrode active material coated portion and a part not coated with the positive electrode active material. Here, the positive electrode active material coated portion is generally rectangular, and the positive electrode active material uncoated portion is The positive electrode active material coating portion is then positioned along at least a portion of the periphery of the current collector. The entire assembly is uniformly pressed at a predetermined pressure to separate the thin portion of the positive electrode active material layer from the flat portion of the positive electrode active material layer. and an insulating member is provided so as to cover at least a part of the positive electrode active material uncoated portion. , to obtain the positive electrode. Next, a negative electrode active material-containing slurry containing a negative electrode active material and a solvent is removed from a portion of the negative electrode current collector. The negative electrode active material is continuously applied in one direction to provide a negative electrode active material-coated portion and a negative electrode active material-uncoated portion. The negative electrode active material coated portion has a generally rectangular shape, which is substantially the same as the positive electrode active material coated portion. The uncoated portion is positioned along at least a portion of the periphery of the positive electrode current collector. The entire negative electrode active material application portion is generally uniformly pressed with a predetermined pressure to separate the thin portion of the negative electrode active material layer and the negative electrode active material. The flat portion of the negative electrode active material layer is formed at the same time, and the density of the thin portion of the negative electrode active material layer is The density of the negative electrode is equal to or less than that of the negative electrode. Next, the generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode are bonded to each other. The positive and negative electrodes are stacked so that they are almost overlapping each other. The negative electrode active material uncoated portion and the negative electrode active material uncoated portion are located on the same side of the rectangle, and the negative electrode active material The boundary between the coated portion and the portion not coated with the negative electrode active material is positioned adjacent to the insulating member, and the negative electrode active material The boundary between the thin portion of the negative electrode active material layer and the flat portion of the negative electrode active material layer is positioned adjacent to the flat portion of the positive electrode active material layer. The positive electrode and the negative electrode are placed one on top of the other so that they overlap. The lithium ion secondary battery element of the second embodiment is manufactured by carrying out at least the above steps. When the positive electrode and the negative electrode are stacked, A separator may be disposed between them.

[0092] The method for producing a lithium ion secondary battery element first includes a step of obtaining a positive electrode. Active material (as mentioned above, a positive electrode active material and a positive electrode containing a binder and a conductive additive, etc., if necessary) A positive electrode active material-containing slurry is obtained, which contains the positive electrode active material (which may be a positive electrode active material mixture) and a solvent. The solvent is an organic solvent capable of dispersing the positive electrode active material, such as N-methylpyrrolidone. The obtained positive electrode active material-containing slurry is applied to one side of the positive electrode current collector. The slurry is applied continuously from the top of the surface toward a predetermined direction. Using a machine such as a bar coater that can coat the positive electrode active material on the surface of the positive electrode current collector, At this time, a part of the positive electrode current collector, for example, a generally rectangular positive electrode current collector, is coated with the slurry. When using a rectangular plate, the positive electrode active material-containing slurry is poured into a portion slightly inside the center from one side of the rectangle. The coating can be started and continued in the direction of the opposite side. The positive electrode active material coating portion is generally rectangular, and the positive electrode active material is positioned along one side of the positive electrode current collector. At this time, the positive electrode active material-containing slurry is applied to the surface of the substrate. The amount of the positive electrode active material-containing slurry applied to the other portions is usually slightly less. Next, the entire area where the positive electrode active material is applied is pressed uniformly at a predetermined pressure. Thereafter, if necessary, it is dried to form a thin layer of the positive electrode active material having a slightly smaller amount of the positive electrode active material applied. The positive electrode active material layer has a flat portion and a positive electrode active material layer flat portion on which the positive electrode active material is applied almost uniformly.

[0093] Next, there is a process for obtaining a negative electrode. First, a negative electrode active material (as described above, a negative electrode active material mixture containing a binder and a conductive additive, etc., In this case, the solvent is used to disperse the negative electrode active material. An organic solvent that can be used is, for example, N-methylpyrrolidone. The negative electrode active material-containing slurry is continuously applied from a part of the negative electrode current collector in one predetermined direction. Preferably, a machine such as a bar coater capable of applying the slurry onto a flat surface is used. The negative electrode active material-containing slurry is applied to the flat surface of the negative electrode current collector. For example, when a generally rectangular negative electrode current collector is used, the negative electrode current collector is located slightly from the center of one side of the rectangle. The application of the negative electrode active material slurry begins from the center of the electrode, and then spreads toward the opposite side. In this way, a generally rectangular negative electrode active material coated portion and A negative electrode active material uncoated portion is provided along one side of the negative electrode current collector. The amount of the slurry applied at the application start end of the slurry containing the inorganic substance is usually slightly less, The other portions are coated with the same amount of negative electrode active material-containing slurry. The entire coated area is pressed uniformly at a predetermined pressure. The negative electrode active material layer had a thin portion where the amount of applied active material was slightly less, and the negative electrode active material was applied almost uniformly. The flat portion of the negative electrode active material layer is formed at the same time. The pressure applied to the starting point of the application of the negative electrode active material-containing slurry is smaller than the pressure applied to other parts. Therefore, the thickness of the thin portion of the negative electrode active material layer where the amount of the negative electrode active material applied is slightly smaller than that of the thin portion of the negative electrode active material layer. The density is the same as or less than the density of the flat part of the negative electrode active material layer where the negative electrode active material is applied almost uniformly. It should be noted that other methods, such as coating a positive electrode active material-containing slurry onto a positive electrode current collector, may be used. In addition, even if the method involves applying a slurry containing a negative electrode active material to a negative electrode current collector, each embodiment of the present invention is Any method can be applied as long as it can obtain the positive electrode and negative electrode used in the embodiment.

[0094] The positive electrode and negative electrode thus obtained were stacked together to form a lithium ion secondary battery element. When the positive electrode and the negative electrode are stacked, the generally rectangular positive electrode active material layer of the positive electrode and the generally rectangular negative electrode active material layer of the negative electrode are stacked. The positive electrode and the negative electrode are stacked so that the rectangular negative electrode active material layer and the rectangular negative electrode active material layer are almost overlapping each other. Putting the positive and negative electrodes together so that the rectangles are almost overlapping with each other generally means The rectangular positive electrode active material layer and the generally rectangular negative electrode active material layer are arranged so that their sides roughly overlap each other. For example, if the shape of the positive electrode active material layer is When the negative electrode active material layer has a rectangular shape, the negative electrode active material layer has a substantially rectangular shape. The positive electrode and the negative electrode are stacked so that the long sides of the rectangle and the long sides of the negative electrode active material layer are roughly overlapped with each other. Here, the shape of the positive electrode active material layer and the shape of the negative electrode active material layer are exactly the same. The positive and negative electrodes do not need to be aligned so that the positive and negative electrode active material layers overlap exactly. The rectangular shape of the positive electrode active material layer and the rectangular shape of the negative electrode active material layer are roughly the same. It is sufficient that they have the same shape and that they roughly overlap.

[0095] At this time, the positive electrode active material uncoated portion of the positive electrode and the negative electrode active material uncoated portion of the negative electrode were formed in the same rectangular shape. The boundary between the negative electrode active material coated portion and the negative electrode active material uncoated portion is adjacent to the insulating member. The boundary between the thin portion of the negative electrode active material layer and the flat portion of the negative electrode active material layer is located in the positive electrode active material layer. The positive electrode and the negative electrode are overlapped so that the flat portions are adjacent to each other. The positive electrode and the negative electrode can be disposed in a positional relationship as shown in FIG.

[0096] Manufacture of a lithium ion secondary battery using the lithium ion secondary battery element of the embodiment The method can be a conventional method and is not particularly limited. The lithium ion secondary battery element is made up of a laminate of a cathode and an anode. The wire is connected by ultrasonic welding or other methods, and then placed in a predetermined position on the exterior material. First, the overlapping portions (flanges) of the positive and negative electrode tabs are heat-sealed. One of the sides that is not the exposed part is heat-sealed to form a bag. Then, the electrolyte is poured into the bag. Finally, the remaining side is heat-sealed under reduced pressure. A lead is a terminal that transfers electricity between the positive or negative electrode in a battery and the outside. Nickel or nickel-plated copper conductors are used as negative electrode tabs for lithium-ion secondary batteries. and an aluminum conductor can be used as the positive electrode tab.

[0097] The embodiments of the present invention have been described above, but the above embodiments have been merely illustrative of the present invention. It is not intended to limit the technical scope of the present invention to any particular embodiment or specific configuration. do not have. [Explanation of symbols]

[0098] 1 positive electrode 11(21, 151, 161, 171, 181, 191, 1101) Positive electrode current collector 12(22, 152, 162, 172, 182, 192, 1102) Positive electrode active material layer 23 (153, 163, 173, 183, 193, 1103) Positive electrode active material coating part 24 (154, 164, 174, 184, 194, 1104) Positive electrode active material uncoated area 25(175, 185, 1105) Thin part of positive electrode active material layer 26(176, 186, 1106) Flat part of positive electrode active material layer 177 Positive electrode current collector periphery 187 (197, 1107) Insulating materials 2 negative electrode 31(41, 251, 261, 271, 281, 291, 2101) Negative electrode current collector 32(42, 252, 262, 272, 282, 292, 2102) Negative electrode active material layer 43 (253, 263, 273, 283, 293, 2103) Negative electrode active material coating part 44(254, 264, 274, 284, 294, 2104) Area not coated with negative electrode active material 45(275, 285, 2105) Thin part of negative electrode active material layer 46(276, 286, 2106) Flat part of negative electrode active material layer 277 (287, 2107) Boundary between the negative electrode active material coated area and the negative electrode active material uncoated area 278 (288, 2108) Boundary between the flat part of the negative electrode active material layer and the thin part of the negative electrode active material layer 3 Separator

Claims

1. A positive electrode in which a positive electrode active material is applied to both sides of a positive electrode current collector in substantially the same shape on at least a part of each of the two sides, the positive electrode current collector has a generally rectangular positive electrode active material layer coated with the positive electrode active material and a positive electrode active material uncoated portion where the positive electrode active material is not coated, the positive electrode active material uncoated portion being located along at least a portion of a peripheral edge portion of the positive electrode current collector; the positive electrode active material layer is composed of a thin portion of the positive electrode active material layer and a flat portion of the positive electrode active material layer; a negative electrode in which a negative electrode active material is applied to at least a portion of both surfaces of a negative electrode current collector in substantially the same shape, the negative electrode current collector has a generally rectangular negative electrode active material layer coated with the negative electrode active material and having substantially the same shape as the positive electrode active material layer, and a negative electrode active material uncoated portion that is not coated with the negative electrode active material, the negative electrode active material uncoated portion being located along at least a part of a peripheral edge portion of the negative electrode current collector, the negative electrode active material layer is composed of a thin portion of the negative electrode active material layer and a flat portion of the negative electrode active material layer; a positive electrode active material layer of a generally rectangular shape and a negative electrode active material layer of a generally rectangular shape, the positive electrode and the negative electrode being stacked together such that the rectangles substantially overlap each other; the positive electrode and the negative electrode are superimposed on each other such that the positive electrode active material uncoated portion of the positive electrode and the negative electrode active material uncoated portion of the negative electrode are located on opposing sides of the rectangle; a boundary between the negative electrode active material layer and the negative electrode active material uncoated portion is located closer to the peripheral edge of the negative electrode current collector than a peripheral edge of the positive electrode current collector adjacent to the negative electrode active material uncoated portion, a boundary portion between the flat portion of the negative electrode active material layer and the thin portion of the negative electrode active material layer is located closer to the center of the negative electrode current collector than a peripheral portion of the positive electrode current collector adjacent to the negative electrode active material uncoated portion, a boundary between the positive electrode active material layer and the positive electrode active material uncoated portion is located closer to the peripheral edge of the positive electrode current collector than a peripheral edge of the negative electrode current collector adjacent to the positive electrode active material uncoated portion, a boundary between the flat portion of the positive electrode active material layer and the thin portion of the positive electrode active material layer is located closer to the center of the positive electrode current collector than a peripheral portion of the negative electrode current collector adjacent to the positive electrode active material uncoated portion, the density of the thin portion of the negative electrode active material layer is lower than the density of the flat portion of the negative electrode active material layer; The lithium ion secondary battery element.

2. 2. The lithium ion secondary battery element according to claim 1, wherein the thickness of the positive electrode active material layer gradually decreases toward the boundary between the positive electrode active material layer and the positive electrode active material uncoated portion.

3. 3. The lithium ion secondary battery element according to claim 1, wherein the thickness of the negative electrode active material layer gradually decreases toward the boundary between the negative electrode active material layer and the negative electrode active material uncoated portion.

4. 4. The lithium ion secondary battery element according to claim 1, further comprising a separator disposed between the positive electrode and the negative electrode.

5. The lithium ion secondary battery element according to claim 4; An electrolyte; A lithium ion secondary battery including, inside an exterior body, a power generating element including the above.

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