Battery and manufacturing method of battery

Abstract

To hardly cause short-circuiting between an end at one side in a width direction of a portion positioned at an outermost peripheral side in an anode sheet in a long belt shape and an end at one side in a width direction of a portion positioned at an outermost peripheral side in a cathode sheet in the long belt shape holding a separator in the long belt shape between the cathode sheet and the anode sheet.SOLUTION: A portion positioned at an outermost peripheral side in a cathode sheet 50 is an outer periphery constitutive part 50X. A separator 60A includes a first opposite part 60A-X which is opposed from an inner peripheral side to the outer periphery constitutive part. An anode sheet 40 includes a second opposite part 40X which is opposed from an inner peripheral side to the first opposite part. An end of the separator at one side G1 protrudes from the anode sheet to one side. An end of a wound body 30 at one side is deformed so as to be closer to a virtual axis IAX. A thickness of an end, at one side in the second opposite part, of a first anode active material 52 which is an anode active material opposed to the first opposite part is smaller than a thickness of the other portion of the first anode active material.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a battery and a method for manufacturing a battery. [Background technology]

[0002] The following Patent Document 1 discloses a battery including a wound electrode assembly. This electrode assembly includes a long strip-shaped positive electrode sheet, a long strip-shaped negative electrode sheet, and a long strip-shaped separator located between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet includes a negative electrode electrode body and a negative electrode active material coated on both sides of the negative electrode electrode body. The wound electrode assembly is formed by winding a laminate of the positive electrode sheet, the negative electrode sheet, and the separator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-57587 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the wound electrode body of the battery of Patent Document 1, there is a risk that one end in the width direction of the outermost part of the negative electrode sheet may come into contact with one end in the width direction of the outermost part of the positive electrode sheet, breaking through a part of the separator that faces this part from the outer periphery. In other words, there is a risk of a short circuit occurring between the negative electrode active material constituting one end in the width direction of the outermost part of the negative electrode sheet and one end in the width direction of the outermost part of the positive electrode sheet.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a battery and a method for manufacturing the battery in which a short circuit is less likely to occur between one end in the width direction of the outermost portion of a long, strip-shaped negative electrode sheet and one end in the width direction of the outermost portion of a long, strip-shaped positive electrode sheet that sandwiches a long, strip-shaped separator between the negative electrode sheet and the battery. [Means for solving the problem]

[0006] A battery according to a first aspect of the present invention is a battery having a wound body obtained by winding a laminate including a negative electrode sheet having a negative electrode body and a negative electrode active material coated on both sides of the negative electrode body, a positive electrode sheet having a positive electrode active material coated on an area of ​​both sides of the positive electrode body except for an end on one side in the width direction, and a long strip-shaped separator located between the negative electrode sheet and the positive electrode sheet, around a virtual axis extending in the width direction, and the outermost portion of the positive electrode sheet is an outer peripheral component portion, and the separator the separator has a first opposing portion facing the outer peripheral component from the inner circumferential side, the negative electrode sheet has a second opposing portion facing the first opposing portion from the inner circumferential side, the one end of the separator protrudes toward the one side from the negative electrode sheet, the one end of the wound body is deformed to approach the imaginary axis, and the thickness of the one end of the first negative electrode active material, which is the negative electrode active material facing the first opposing portion, at the second opposing portion is smaller than the thickness of other portions of the first negative electrode active material.

[0007] In the battery of the second aspect of the present invention, the thickness of the second negative electrode active material, which is the negative electrode active material that does not face the first opposing portion, at the end portion on one side of the battery of the first aspect of the present invention is smaller than the thickness of other portions of the second negative electrode active material.

[0008] In a third aspect of the battery of the present invention, in the first or second aspect of the battery of the present invention, the thickness of the first negative electrode active material at the end on one side is smaller than the thickness of other parts of the first negative electrode active material over the entire longitudinal direction of the negative electrode body.

[0009] A fourth aspect of the battery of the present invention is the battery of the first or third aspect, wherein the thickness of the second negative electrode active material, which is the negative electrode active material that does not face the first opposing portion, at the end portion on one side is smaller than the thickness of other portions of the second negative electrode active material over the entire longitudinal direction of the negative electrode body.

[0010] A manufacturing method for a battery according to a fifth aspect of the present invention includes a negative electrode sheet constructing step of coating one surface of a long strip-shaped negative electrode body with a first negative electrode active material so that a thickness at one end of the negative electrode body in a width direction is smaller than a thickness at other portions, and coating the other surface of the negative electrode body with a second negative electrode active material to construct a negative electrode sheet; a stack constructing step of stacking the negative electrode sheet, a long strip-shaped positive electrode sheet, and a long strip-shaped separator located between the negative electrode sheet and the positive electrode sheet, and constructing a stack by causing the one end of the separator to protrude toward the one side beyond the negative electrode sheet; and a wound body constructing step of winding the laminate around a virtual axis extending in the width direction to construct a wound body, and deforming the one end of the wound body so as to approach the virtual axis.

[0011] A sixth aspect of the present invention relates to a method for manufacturing a battery of the fifth aspect of the battery, and the negative electrode sheet constructing step includes the steps of: applying the first negative electrode active material to the one surface of the negative electrode body; making the thickness of the first negative electrode active material at a central portion in the width direction smaller than the thickness of the first negative electrode active material at any portion other than the central portion over the entire longitudinal area of ​​the negative electrode sheet; and cutting the negative electrode sheet along midpoints of both side edges of the central portion over the entire area. Effect of the Invention

[0012] In the battery according to the first aspect of the present invention, the thickness of the first negative electrode active material, which is the negative electrode active material facing the first opposing portion in the second opposing portion of the negative electrode sheet, at one end in the width direction is smaller than the thickness of the other portion of the first negative electrode active material. Therefore, there is little risk that the end of the first negative electrode active material on one side in the width direction will come into contact with the first opposing portion of the separator with a strong force. Therefore, there is little risk that the end of the first negative electrode active material on one side in the width direction will come into contact with the peripheral component of the positive electrode sheet while breaking the first opposing portion located on the outer periphery side of the end. Therefore, it is difficult for a short circuit to occur between the end of the second opposing portion on one side in the width direction, which is the portion located on the outermost side of the negative electrode sheet, and the end of the peripheral component on one side in the width direction, which is the portion located on the outermost side of the positive electrode sheet.

[0013] In the battery according to the second aspect of the present invention, the thickness of one end of the second negative electrode active material, which is the negative electrode active material not facing the first opposing portion, is smaller than the thickness of the other portion of the second negative electrode active material, and therefore there is little risk that the one end of the second negative electrode active material will break the portion of the separator located on the inner periphery of the end and come into contact with a part of the positive electrode sheet located on the inner periphery of the broken portion.

[0014] According to the battery of the third aspect of the present invention, a short circuit is unlikely to occur between the first negative electrode active material of the negative electrode sheet and the positive electrode sheet over the entire longitudinal area of ​​the negative electrode body.

[0015] According to the battery of the fourth aspect of the present invention, the second negative electrode active material of the negative electrode sheet and the positive electrode sheet are less likely to short-circuit over the entire lengthwise area of ​​the negative electrode body.

[0016] According to the battery manufacturing method of the fifth aspect of the present invention, it is possible to manufacture a battery that is less likely to short-circuit between one end in the width direction of the outermost portion of the long strip-shaped negative electrode sheet and one end in the width direction of the outermost portion of the long strip-shaped positive electrode sheet that sandwiches a long strip-shaped separator between the negative electrode sheet and the long strip-shaped positive electrode sheet.

[0017] In the battery of the sixth aspect of the present invention, it becomes easy to manufacture a negative electrode sheet so that the thickness at one end in the width direction of the first negative electrode active material, which is the negative electrode active material facing the first opposing portion, is smaller than the thickness of other parts of the first negative electrode active material. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a front view showing a lithium-ion secondary battery according to an embodiment. [Diagram 2] FIG. 1 is an exploded perspective view of a lithium-ion secondary battery according to an embodiment. [Diagram 3] FIG. 2 is an exploded perspective view of a positive electrode sheet, a separator, and a negative electrode sheet. [Figure 4] FIG. 2 is a schematic side view of a manufacturing apparatus. [Diagram 5] 5 is a cross-sectional view taken along the line 5-5 in FIG. [Figure 6] FIG. 2 is a plan view of the negative electrode sheet after passing through a coating device of the manufacturing apparatus. [Figure 7] FIG. 2 is a plan view of the negative electrode sheet after it has passed through a cutting tool of the manufacturing equipment. [Figure 8] FIG. 2 is a plan view of the negative electrode sheet after it has passed through a cutting tool of the manufacturing equipment. [Figure 9] 2 is a cross-sectional view taken along a plane perpendicular to the longitudinal direction of a laminate of a positive electrode sheet, a separator, and a negative electrode sheet. FIG. [Figure 10] 10 is a perspective view showing the wound body cut along the arrow line 10-10 in FIG. 2. [Figure 11] FIG. 2 is a vertical sectional front view of a main part of a wound body, with the vertical center portion omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, a battery according to an embodiment will be described with reference to the drawings. The battery according to the embodiment is, for example, a lithium-ion secondary battery serving as a cell battery constituting a battery module used as an on-board power source for electric vehicles, hybrid vehicles, etc. In each drawing, arrow D indicates the longitudinal direction of the lithium-ion secondary battery (battery) 10, arrow E indicates the depth direction of the lithium-ion secondary battery 10, and arrow F indicates the up-down direction of the lithium-ion secondary battery 10.

[0020] [Configuration of lithium-ion secondary battery 10] As shown in FIGS. 1 and 2, the lithium ion secondary battery 10 includes a lid assembly 20, a wound body (electrode body) 30, and a battery case 70.

[0021] (battery case 70) The battery case 70 is made of, for example, aluminum, and has a rectangular parallelepiped shape with an open top.

[0022] (Lid Assembly 20) The lid assembly 20 includes a lid member 21, a negative electrode current collector terminal 22 as a current collector terminal, a positive electrode current collector terminal 23 as a current collector terminal, a negative electrode external terminal 24 as an external terminal, and a positive electrode external terminal 25 as an external terminal.

[0023] <Cover member 21> The lid member 21 is made of, for example, aluminum, and is a plate-like member extending in the longitudinal direction D. The lid member 21 is provided with a safety valve 21A and a cap 26 that closes the injection port 21B.

[0024] The safety valve 21A opens when the internal pressure of the battery case 70 reaches a predetermined pressure, and discharges gas generated inside the battery case 70.

[0025] The injection port 21B is a through-hole that passes through the lid member 21 in the vertical direction. The injection port 21B is used when injecting an electrolyte (not shown) into the battery case 70. A cap 26 is attached to the injection port 21B in an airtight and liquid-tight manner, for example, by laser welding.

[0026] <Negative electrode current collector terminal 22 and negative electrode external terminal 24> The negative electrode current collector terminal 22 and the negative electrode external terminal 24 are formed of, for example, copper, and are provided at the other end of the cover member 21 in the longitudinal direction D. The negative electrode current collector terminal 22 is a rectangular plate-like member whose plate thickness direction is the depth direction E. The negative electrode external terminal 24 is electrically connected to the negative electrode current collector terminal 22 and exposed to the outside of the cover member 21.

[0027] <Positive electrode current collector terminal 23 and positive electrode external terminal 25> The positive electrode current collector terminal 23 and the positive electrode external terminal 25 are made of, for example, aluminum, and are provided at one end of the cover member 21 in the longitudinal direction D. The positive electrode current collector terminal 23 is a rectangular plate-like member whose plate thickness direction is the depth direction E. The positive electrode external terminal 25 is electrically connected to the positive electrode current collector terminal 23, and is exposed to the outside of the cover member 21.

[0028] (Wound body 30) As shown in FIGS. 2 and 9, the wound body 30 has a power generating body 31, a negative electrode current collecting portion 46, and a positive electrode current collecting portion .

[0029] As shown in Figs. 3 and 9, the wound body 30 is composed of a laminate 62 having a long strip-shaped negative electrode sheet 40 as an electrode sheet, a long strip-shaped positive electrode sheet 50 as an electrode sheet, and two long strip-shaped separators 60A and 60B. The negative electrode sheet 40, the positive electrode sheet 50, and the separators 60A and 60B are flexible. As shown in Figs. 10 and 11, the wound body 30 is composed by winding the laminate 62 around a virtual axis IAX (see Figs. 2, 10, and 11) extending in the width direction G of the negative electrode sheet 40, the positive electrode sheet 50, and the separators 60A and 60B. As shown in Figs. 2 and 10, the wound body 30 has a flat shape.

[0030] <Negative electrode sheet 40> 3, the negative electrode sheet 40 includes a long strip-shaped negative electrode body 41, a first negative electrode active material 42 coated on one surface of the negative electrode body 41, and a second negative electrode active material 43 coated on the other surface of the negative electrode body 41. The negative electrode body 41 is made of, for example, copper foil. The first negative electrode active material 42 and the second negative electrode active material 43 each include an inner periphery side negative electrode active material which is a portion on the negative electrode body 41 side, and an outer periphery side negative electrode active material which is a portion on the opposite side to the negative electrode body 41.

[0031] The negative electrode sheet 40 is manufactured using a manufacturing apparatus 80 shown in Fig. 4. The manufacturing apparatus 80 includes a pair of upper and lower transport rollers 81 and a pair of upper and lower transport rollers 82 arranged downstream of the transport rollers 82. The long strip-shaped negative electrode body 41 (negative electrode sheet 40) is sandwiched between the upper and lower transport rollers 81 and the upper and lower transport rollers 82, and the transport rollers 81 and 82 rotate in the direction of arrow R in Fig. 4, thereby transporting the negative electrode body 41 from the upstream side to the downstream side along the arrow A in Fig. 4. Therefore, tension is always applied to the negative electrode body 41 (negative electrode sheet 40) between the transport rollers 81 and the transport rollers 82 in a direction parallel to the transport direction.

[0032] As shown in FIG. 4, the manufacturing apparatus 80 includes, in order from the upstream side, a coating device 83, a drying furnace 84, a pressing device 85, a cutting tool 86, and a cutting tool 87. The coating device 83 coats the first negative electrode active material 42 on the upper surface of the negative electrode body 41 transported downstream by the transport roller 81, and coats the second negative electrode active material 43 on the lower surface of the negative electrode body 41. As shown in FIG. 6, the coating device 83 coats the first negative electrode active material 42 only on the region excluding both sides in the width direction G of the upper surface of the negative electrode body 41. Similarly, although not shown, the coating device 83 coats the second negative electrode active material 43 only on the region excluding both sides in the width direction G of the lower surface of the negative electrode body 41. Therefore, a negative electrode current collecting portion 46 to which the first negative electrode active material 42 and the second negative electrode active material 43 are not coated is formed on both sides in the width direction G of the negative electrode body 41.

[0033] The drying furnace 84 has a function of drying the first negative electrode active material 42 and the second negative electrode active material 43 applied to both sides of the negative electrode body 41. The pressing device 85 is composed of, for example, a pair of upper and lower pressure rollers. The pressing device 85 adjusts the thickness of the negative electrode sheet 40 by applying pressure to both sides of the negative electrode body 41 (the first negative electrode active material 42, the second negative electrode active material 43).

[0034] As shown in FIG. 5, the pair of upper and lower cutting tools 86 are metal members having a substantially U-shaped cross section. The lower part of the upper cutting tool 86 is located at the same height as the first negative active material 42, and the upper part of the lower cutting tool 86 is located at the same height as the second negative active material 43. As shown in FIG. 7, the dimensions of the upper and lower cutting tools 86 in the width direction G are shorter than the dimensions of the negative electrode body 41 in the width direction G. Furthermore, the upper and lower cutting tools 86 are located at the center of the width direction G of the negative electrode body 41 in a plan view. Therefore, as shown in FIG. 7, the first negative active material 42 is cut from a portion located downstream of the upper cutting tool 86 on the upper surface of the negative electrode body 41, and a removed portion 44 is formed in the center of the width direction G on the upper surface of the negative electrode body 41. Although not shown in the figure, the second negative electrode active material 43 is cut from a portion of the lower surface of the negative electrode body 41 that is located downstream of the lower cutting tool 86, and a removed portion 44 is formed in the center of the width direction G of the lower surface of the negative electrode body 41.

[0035] The pair of upper and lower cutting tools 87 are made of metal, for example. The lower end of the upper cutting tool 87 and the upper end of the lower cutting tool 87 are located at the same height as the negative electrode body 41. Furthermore, as shown in FIG. 8, the upper and lower cutting tools 87 are located at the center position CP of the width direction G of the negative electrode body 41 in a plan view. Therefore, as shown in FIG. 8, the part of the negative electrode body 41 located downstream of the upper and lower cutting tools 87 is cut along the center position CP, and the negative electrode body 41 (negative electrode sheet 40) is separated into two parts. This completes the negative electrode sheet 40 shown in FIG. 3 and FIG. 9. As described above, the cutting tool 86 is a member having a cross-sectional shape that is approximately U-shaped. Therefore, as shown in FIG. 9, the cross-sectional shape of the removed part 44 formed above and below the end on one side in the width direction G of the completed negative electrode sheet 40 is a shape similar to a circular arc with a central angle of 90°. In the following description, one side in the width direction G is referred to as "one side G1". The removed portion 44 in this embodiment is constituted by the ends of one side G1 of the first negative electrode active material 42 and the second negative electrode active material 43. That is, the ends of one side G1 of the first negative electrode active material 42 and the second negative electrode active material 43 are gradually reduced in thickness toward the one side G1, but both surfaces of the negative electrode body 41 are not exposed at the ends of one side G1 of the negative electrode sheet 40.

[0036] <Positive electrode sheet 50> As shown in FIG. 3, the positive electrode sheet 50 includes a long strip-shaped positive electrode body 51, a first positive electrode active material (positive electrode active material) 52 coated on one side of the positive electrode body 51, and a second positive electrode active material (positive electrode active material) 53 coated on the other side of the positive electrode body 51. The first positive electrode active material 52 and the second positive electrode active material 53 have an inner periphery side positive electrode active material which is a portion on the positive electrode body 51 side, and an outer periphery side positive electrode active material which is a portion on the opposite side to the positive electrode body 51. The positive electrode body 51 is made of, for example, aluminum foil. As shown in FIG. 3, the first positive electrode active material 52 and the second positive electrode active material 53 are coated only on the regions of both sides of the positive electrode body 51 except for the side portions on one side G1. Therefore, at the end of one side G1 of the positive electrode body 51, a positive electrode current collecting portion 54 on which the first positive electrode active material 52 and the second positive electrode active material 53 are not applied is formed.

[0037] <Separator 60A, 60B> The separators 60A and 60B are made of an insulating material such as polypropylene or polyethylene.

[0038] As shown in Fig. 3 and Fig. 9, the dimensions of the separators 60A and 60B in the width direction G are larger than those of the negative electrode sheet 40 and the positive electrode sheet 50. The separator 60A faces the first negative electrode active material 42 of the negative electrode sheet 40 and the second positive electrode active material 53 of the positive electrode sheet 50, and the separator 60B faces the first positive electrode active material 52 of the positive electrode sheet 50. That is, the negative electrode sheet 40, the separator 60A, the positive electrode sheet 50, and the separator 60B are laminated in this order, and the negative electrode sheet 40, the positive electrode sheet 50, and the separators 60A and 60B form a laminate 62. As shown in Fig. 9, the end of one side G1 of the positive electrode current collecting portion 54 of the positive electrode body 51 is located on one side G1 of the separators 60A and 60B. The other end in the width direction of the negative electrode current collecting portion 46 of the negative electrode body 41 is located on the other side in the width direction G of the separators 60A, 60B.

[0039] The laminate 62 is wound around an imaginary axis IAX (see FIGS. 2, 10, and 11) extending in the width direction G to form the wound body 30 shown in FIGS. 2 and 10. The positive electrode current collector 54 is wound to form an end portion on one side G1 of the wound body 30, and the negative electrode current collector 46 is wound to form an end portion on the other side of the wound body 30. Furthermore, the region between the negative electrode current collector 46 and the positive electrode current collector 54 of the wound body 30 is the power generating body 31. The power generating body 31 has a function of storing electric energy of the lithium ion secondary battery 10.

[0040] The lower end of the negative electrode collector terminal 22 is connected to the vertical center of the negative electrode collector 46 of the wound body 30 by resistance welding, and the lower end of the positive electrode collector terminal 23 is connected to the vertical center of the positive electrode collector 54 by ultrasonic welding. Therefore, as shown in FIG. 2, the other end of the wound body 30 is deformed to approach the imaginary axis IAX, and the other end of the wound body 30 is collected. That is, the dimension in the depth direction E of the other end of the width direction G of the wound body 30 including the negative electrode collector 46 becomes smaller. More specifically, the dimension in the depth direction E of the center of the other end of the width direction G of the wound body 30 including the negative electrode collector 46 becomes smaller than the upper and lower parts of the other end. Also, the end of one side G1 of the wound body 30 is deformed to approach the imaginary axis IAX, and the end of one side G1 of the wound body 30 is collected. That is, the dimension in the depth direction E of the end of one side G1 of the wound body 30 including the positive electrode current collector 54 is reduced. More specifically, the dimension in the depth direction E of the center of the end of one side G1 of the wound body 30 including the positive electrode current collector 54 is smaller than the upper and lower parts of the end of the one side G1. Furthermore, the negative electrode current collector terminal 22, the positive electrode current collector terminal 23, and the wound body 30 are housed together in the internal space of the battery case 70 filled with the electrolyte. Furthermore, the lid member 21 is fixed to the upper end of the battery case 70 by laser welding, thereby completing the lithium ion secondary battery 10 shown in FIG. 1. The upper end opening of the battery case 70 is closed by the lid member 21 in an airtight and liquid-tight state.

[0041] [Functions and Effects of Lithium-Ion Secondary Battery 10] When the lithium ion secondary battery 10 is completed as described above, the negative electrode current collector 46 is deformed by the lower end of the negative electrode current collector terminal 22 inside the battery case 70, and the positive electrode current collector 54 is deformed by the positive electrode current collector terminal 23. Therefore, as shown in FIG. 11, the end 60B-1 on one side G1 of the separator 60B, the positive electrode current collector 54 of the positive electrode body 51, and the end 60A-1 on one side G1 of the separator 60A are bent so as to approach the imaginary axis IAX. Therefore, the parts of the end 60B-1, the positive electrode current collector 54, and the end 60A-1 adjacent to each other in the radial direction centered on the imaginary axis IAX contact each other with a predetermined force. However, the removed part 44 is formed at the end of the one side G1 of the first negative electrode active material 42 over the entire area of ​​the longitudinal direction LD (see FIG. 3, FIG. 6-FIG. 8) of the negative electrode sheet 40. That is, the thickness of the end of the one side G1 of the first negative electrode active material 42 facing the end 60A-1 (separator 60A) is smaller than the thickness of the other portion of the first negative electrode active material 42. Therefore, there is little risk that the end of the one side G1 of the first negative electrode active material 42 will contact the end 60A-1 with a strong force. That is, in the entire area of ​​the longitudinal direction LD of the negative electrode sheet 40, there is little risk that the end of the one side G1 of the first negative electrode active material 42 will break the end 60A-1 and contact the positive electrode current collector 54 located on the outer periphery side of the end 60A-1. Therefore, a short circuit is unlikely to occur between the negative electrode sheet 40 and the positive electrode sheet 50 at the end of the one side G1 of the wound body 30.

[0042] In particular, the positive electrode current collector 54 of the outer peripheral component 50X (see FIG. 11) of the positive electrode sheet 50 is more likely to bend toward the virtual axis IAX side than the positive electrode current collector 54 of the positive electrode sheet 50 at a portion other than the outer peripheral component 50X. Here, the outer peripheral component 50X is a part of the positive electrode sheet 50 exposed on the outer peripheral surface of the wound body 30 when the separator 60B is omitted from the wound body 30 and the wound body 30 is viewed from the outer peripheral side. Furthermore, here, a part of the separator 60A facing the outer peripheral component 50X from the inner peripheral side is referred to as the first opposing portion 60A-X (see FIG. 11). In other words, the first opposing portion 60A-X is a part of the separator 60A exposed on the outer peripheral surface of the wound body 30 when the separator 60B and the positive electrode sheet 50 are omitted from the wound body 30 and the wound body 30 is viewed from the outer peripheral side. The end 60A-1 of the first opposing portion 60A-X is more likely to bend toward the imaginary axis IAX than the end 60A-1 of the separator 60A other than the first opposing portion 60A-X. Furthermore, a part of the negative electrode sheet 40 that faces the first opposing portion 60A-X from the inner circumferential side is referred to as the second opposing portion 40X (see FIG. 11). That is, the second opposing portion 40X is a part of the negative electrode sheet 40 that is exposed on the outer circumferential surface of the wound body 30 when the separator 60B, the positive electrode sheet 50, and the separator 60A are omitted from the wound body 30 and the wound body 30 is viewed from the outer circumferential side. Although the end 60A-1 of the first opposing portion 60A-X is more likely to bend toward the imaginary axis IAX than the end 60A-1 of a portion of the separator 60A other than the first opposing portion 60A-X, since the removed portion 44 is formed at the end of one side G1 of the first negative electrode active material 42 of the second opposing portion 40X, there is little risk that the end of one side G1 of the first negative electrode active material 42 of the second opposing portion 40X will come into contact with the positive electrode current collecting portion 54 of the outer peripheral component 50X while breaking the end 60A-1 of the first opposing portion 60A-X.

[0043] Furthermore, in the entire area of ​​the longitudinal direction DL of the negative electrode sheet 40, a removed portion 44 is formed at the end of one side G1 of the second negative electrode active material 43. That is, the thickness of the end of one side G1 of the second negative electrode active material 43 facing the end 60B-1 (separator 60B) is smaller than the thickness of other parts of the second negative electrode active material 43. Therefore, there is little risk that the end of one side G1 of the second negative electrode active material 43 will contact the end 60B-1 with a strong force. That is, in the entire area of ​​the longitudinal direction DL of the negative electrode sheet 40, there is little risk that the end of one side G1 of the second negative electrode active material 43 will break the end 60B-1 and contact the positive electrode current collector 54 located on the inner periphery side of the end 60B-1.

[0044] Furthermore, the force acting from the second opposing portion 40X to the separator 60B located on the inner periphery side of the second opposing portion 40X is likely to be greater than the force acting from the remainder, which is a portion other than the second opposing portion 40X of the negative electrode sheet 40, to the separator 60B located on the inner periphery side of the remainder. However, since the removed portion 44 is formed at the end of one side G1 of the second negative electrode active material 43 of the second opposing portion 40X, there is little risk that the end of one side G1 of the second negative electrode active material 43 of the second opposing portion 40X will break the end 60B-1 located on the inner periphery side of the second opposing portion 40X and come into contact with the positive electrode current collector 54 located on the inner periphery side of the end 60B-1.

[0045] Furthermore, when the negative electrode sheet 40 is manufactured by the manufacturing apparatus 80, the cutting tool 86 cuts the first negative electrode active material 42 and the second negative electrode active material 43 at the center in the width direction G of the negative electrode body 41 that is subjected to tension in a direction parallel to the transport direction. Therefore, the cutting tool 86 can cut the first negative electrode active material 42 and the second negative electrode active material 43 more easily than when the cutting tool 86 cuts the first negative electrode active material 42 and the second negative electrode active material 43 at the side edge portions in the width direction G of the negative electrode body 41. Therefore, it is easy to make the shape of the part to be removed 44 provided in the negative electrode sheet 40 closer to the designed shape of the part to be removed 44.

[0046] Furthermore, after the first negative electrode active material 42 and the second negative electrode active material 43 are dried by the drying furnace 84, the thickness of the negative electrode sheet 40 is adjusted by the pressing device 85. Therefore, the manufacturing device 80 can adjust the thickness of the negative electrode sheet 40 with high accuracy, compared to a case in which the thickness of the negative electrode sheet 40 is adjusted by the pressing device 85 before the first negative electrode active material 42 and the second negative electrode active material 43 are dried.

[0047] Although the battery and the method for manufacturing the battery according to the embodiment have been described above, the design of the battery can be appropriately modified without departing from the gist of the present invention.

[0048] For example, the removed portion 44 may be provided only in the second opposing portion 40X of the negative electrode sheet 40.

[0049] Furthermore, the second negative electrode active material 43 may not be provided with the portion to be removed 44, and only the first negative electrode active material 42 may be provided with the portion to be removed 44.

[0050] Furthermore, the shape of the removed portion 44 may be different from that of the embodiment. For example, the cross-sectional shape of the removed portion 44 may be a shape other than a circular arc. Furthermore, the first negative electrode active material 42 may be completely removed from the end of one side G1 of the first negative electrode active material 42. However, in either case, the end of one side G1 of the negative electrode active material needs to be located closer to one side G1 than the end of one side G1 of the positive electrode active material.

[0051] Furthermore, the cutting tool 86 may be omitted from the manufacturing apparatus 80, and the coating device 83 may coat the first negative electrode active material 42 and the second negative electrode active material 43 only in areas excluding the central and both side portions in the width direction G on both sides of the negative electrode body 41.

[0052] Furthermore, when manufacturing the negative electrode sheet 40 by the manufacturing apparatus 80, the dimension in the width direction G of the negative electrode body 41 transported by the transport rollers 81 and 82 may be set to half that of the above-mentioned negative electrode body 41, and the first negative electrode active material 42 and the second negative electrode active material 43 may be provided in an area excluding one side edge portion in the width direction G on both sides of this negative electrode body 41.

[0053] Furthermore, a cutting tool 86 may be provided downstream of the coating device 83 and upstream of the drying furnace 84 in the manufacturing apparatus 80. In this case, the cutting tool 86 cuts the first negative electrode active material 42 and the second negative electrode active material 43 in an undried state, so that the cutting tool 86 can more easily cut the first negative electrode active material 42 and the second negative electrode active material 43 compared to the above embodiment. [Explanation of symbols]

[0054] 10 Lithium-ion secondary battery (battery) 30 Wound body (electrode body) 40 Negative electrode sheet 40X 2nd opposing part 41 Negative electrode body 42 First negative electrode active material (negative electrode active material) 43 Second negative electrode active material (negative electrode active material) 50 Positive electrode sheet 50X Outer periphery 60A Separator 60A-X 1st opposing part 60B Separator G1 One side

Claims

1. A battery having a wound body formed by winding a laminate including a long strip-shaped negative electrode sheet having a negative electrode body and a negative electrode active material coated on both surfaces of the negative electrode body, a long strip-shaped positive electrode sheet having a positive electrode body and a positive electrode active material coated on a region excluding one end portion in the width direction on both surfaces of the positive electrode body, and a long strip-shaped separator positioned between the negative electrode sheet and the positive electrode sheet around a virtual axis extending in the width direction, wherein a portion located on the outermost peripheral side among the positive electrode sheets is an outer peripheral component portion, the separator has a first facing portion facing the outer peripheral component portion from the inner peripheral side, the negative electrode sheet has a second facing portion facing the first facing portion from the inner peripheral side, one end portion of the separator on one side protrudes to the one side from the negative electrode sheet, one end portion of the wound body is deformed so as to approach the virtual axis, and a battery in which a thickness of one end portion in the second facing portion of a first negative electrode active material, which is the negative electrode active material facing the first facing portion, is smaller than a thickness of other portions of the first negative electrode active material.

2. The battery according to claim 1, wherein a thickness of one end portion in the second negative electrode active material, which is the negative electrode active material not facing the first facing portion, is smaller than a thickness of other portions of the second negative electrode active material.

3. The battery according to claim 1 or claim 2, wherein a thickness of one end portion in the first negative electrode active material is smaller than a thickness of other portions of the first negative electrode active material throughout a longitudinal direction of the negative electrode body.

4. The battery according to claim 1, wherein a thickness of one end portion in the second negative electrode active material, which is the negative electrode active material not facing the first facing portion, is smaller than a thickness of other portions of the second negative electrode active material throughout a longitudinal direction of the negative electrode body.

5. A negative electrode sheet forming step of forming a negative electrode sheet by coating a first negative electrode active material on one surface of a long strip-shaped negative electrode body such that a thickness of one end portion in the width direction of the negative electrode body is smaller than a thickness of other portions, and coating a second negative electrode active material on the other surface of the negative electrode body, a laminate forming step of laminating the negative electrode sheet, a long strip-shaped positive electrode sheet, and a long strip-shaped separator positioned between the negative electrode sheet and the positive electrode sheet, and protruding one end portion of the separator to the one side from the negative electrode sheet to form a laminate, and A winding body forming step of winding the laminate around a virtual axis extending in the width direction to form a winding body, and deforming one end portion of the winding body to approach the virtual axis. A method for manufacturing a battery having the same.

6. The negative electrode sheet forming step includes: A step of coating the first negative electrode active material on one surface of the negative electrode body; A step of making the thickness of the central portion in the width direction of the first negative electrode active material smaller than the thickness of portions other than the central portion of the first negative electrode active material over the entire longitudinal direction of the negative electrode sheet; and A step of cutting the negative electrode sheet along an intermediate position between both side edges of the central portion over the entire area. The method for manufacturing a battery according to claim 5, having the same.

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