Battery

Abstract

This battery has a negative electrode, a positive electrode, and a separator provided between the negative electrode and the positive electrode. The negative electrode has a negative electrode current collector layer and a negative electrode active material layer laminated on the negative electrode current collector layer. The positive electrode has a positive electrode current collector layer and a positive electrode active material layer laminated on the positive electrode current collector layer. The negative electrode active material layer has a first negative electrode mixture layer laminated on the negative electrode current collector layer, and a second negative electrode mixture layer laminated on the first negative electrode mixture layer. The negative electrode current collector layer is divided into a laminated part in which the first negative electrode mixture layer and / or the second negative electrode mixture layer are laminated, and a side part that is an exposed part in which the negative electrode current collector layer is exposed. The separator has an adhesion part that adheres to the second negative electrode mixture layer, and a contact part that contacts the side part.

Description

Battery

[0001] The present invention relates to a battery.

[0002] Conventionally, a battery including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode is known. For example, Patent Document 1 discloses a battery including a negative electrode having an electrode base, a first negative electrode mixture layer stacked on the electrode base, and a second negative electrode mixture layer stacked on the first negative electrode mixture layer.

[0003] Japanese National Publication of International Patent Application No. 2023-505132

[0004] However, in the above-described conventional technology, there is a risk of short circuit between the positive electrode and the negative electrode. Accordingly, there is a demand for suppressing short circuit between the positive electrode and the negative electrode.

[0005] A battery according to a preferred aspect of the present invention includes: a first electrode that is one of a positive electrode and a negative electrode; a second electrode that is the other of the positive electrode and the negative electrode; and a separator disposed between the first electrode and the second electrode, wherein the first electrode includes a first electrode base and a first active material layer stacked on the first electrode base, the second electrode includes a second electrode base and a second active material layer stacked on the second electrode base, the first active material layer includes a first mixture layer stacked on the first electrode base and a second mixture layer stacked on the first mixture layer, the first electrode base is divided into a stacked portion where one or both of the first mixture layer and the second mixture layer are stacked, and an exposed portion where the first electrode base is exposed, and the separator has an adhesion portion that adheres to the second mixture layer and a contact portion that contacts the exposed portion.

[0006] Short circuit between the positive electrode and the negative electrode can be suppressed.

[0007] A perspective view showing the battery 1 of the embodiment. A perspective view showing the battery 1 partially disassembled. A perspective view showing the charge / discharge body 100 of Figure 2. A perspective view showing the components around the positive terminal 310 and negative terminal 320 of the battery 1 disassembled. A side view showing a cross-sectional view of the components around the positive terminal 310 of the battery 1. A side view showing a cross-sectional view of the components around the negative terminal 320 of the battery 1. A perspective view showing a disassembled view of the components around the opening valve 430 and sealing plug 440 of the battery 1. A side view showing a cross-sectional view of a part of the charge / discharge body 100A in the comparative embodiment. A side view showing a cross-sectional view of a part of the charge / discharge body 100. A side view showing a cross-sectional view of a part of the charge / discharge body 101 in the second embodiment. A side view showing a cross-sectional view of a part of the charge / discharge body 102 in the first modified example. A side view showing a cross-sectional view of a part of the charge / discharge body 103 in the second modified example.

[0008] Embodiments for implementing this disclosure will be described with reference to the drawings. In order to facilitate understanding of each embodiment, the size and proportions of the components may be exaggerated in each drawing. In each drawing, the same reference numerals are used for the same components. In each drawing, the longitudinal direction X, the short direction Y, and the height direction Z of the battery 1 are indicated by arrows. In each drawing, the longitudinal direction X, the short direction Y, and the height direction Z of the battery 1 indicate the relative positional relationship within the same drawing. That is, if the battery 1 is rotated 180 degrees and the top and bottom surfaces are reversed, or if the battery 1 is rotated 90 degrees and the top surface is positioned as a side surface, the longitudinal direction X, the short direction Y, and the height direction Z of the battery 1 will change.

[0009] (Configuration of Battery 1 in the Embodiment) The configuration of Battery 1 will be described with reference to Figures 1 to 9.

[0010] Figure 1 is a perspective view showing a battery 1 of an embodiment. Note that Figure 1 shows an example of the external appearance of the battery 1. The battery 1 is, for example, a secondary battery. For example, the battery 1 is a lithium-ion battery.

[0011] The battery 1 has elements that can be seen from its appearance, such as electrode terminals 300, an outer casing 400 that houses or attaches the components of the battery 1, and a seal 600 that seals the components of the battery 1 and the outer casing 400. The details of the configuration of the battery 1 will be described later in Figure 2 and subsequent figures, but for example, the electrode terminals 300 have a positive electrode terminal 310 and a negative electrode terminal 320, and the seal 600 has a positive electrode gasket 610 and a negative electrode gasket 620. The outer casing 400 also has, for example, a container 410, a lid 420, a cleavage valve 430 provided on the lid 420, and a sealing plug 440. The lid 420 is welded to the container 410.

[0012] In this embodiment, one direction along the axis perpendicular to the surface of the lid 420 corresponds to the height direction Z. Note that "perpendicular" includes not only strictly perpendicular but also substantially perpendicular (for example, perpendicular within the margin of error). Also, when viewing the battery 1 from the height direction Z, the longitudinal direction and the short direction of the battery 1 correspond to the longitudinal direction X and the short direction Y, respectively. Hereafter, the height direction Z (the direction pointed to by the Z-axis arrow) may be referred to as "up," and the opposite direction of the height direction Z may be referred to as "down." Furthermore, "elements α and β are stacked" means that elements α and β are aligned vertically, and it is not necessary for elements α and β to be in direct contact.

[0013] Furthermore, the line A1-A2 in Figure 1 indicates the cross-sectional area of ​​the cross-sectional view shown in Figure 5, and the line B1-B2 in Figure 1 indicates the cross-sectional area of ​​the cross-sectional view shown in Figure 6.

[0014] Figure 2 is a perspective view showing a partially disassembled battery 1.

[0015] In addition to the electrode terminals 300, outer casing 400, and sealing body 600 shown in Figure 1, the battery 1 also includes a charge / discharge element 100 for charging and discharging electricity, a current collector 200 connected to the charge / discharge element 100, and an insulator 500 that insulates the components of the battery 1 from the outer casing 400.

[0016] The charge / discharge unit 100 charges and discharges electricity as described above. For example, the charge / discharge unit 100 has a positive electrode 110, a negative electrode 120, and a separator 130. Furthermore, the charge / discharge unit 100 has an electrolyte 140 as shown in Figures 5 and 6. Details of the charge / discharge unit 100 will be described later in Figure 3. The positive electrode 110 is an example of a "positive electrode," and the negative electrode 120 is an example of a "negative electrode."

[0017] As described above, the current collector 200 is connected to the charge / discharge unit 100. The current collector 200 is also referred to as a current collector plate. For example, the current collector 200 has a positive electrode current collector plate 210 and a negative electrode current collector plate 220. The positive electrode current collector plate 210 makes electrical contact between the positive electrode 110 and the positive electrode terminal 310 of the electrode terminal 300. For example, the positive electrode current collector plate 210 includes a joint portion 212ca joined to the positive electrode 110 of the charge / discharge unit 100. That is, the positive electrode current collector plate 210 is connected to the positive electrode 110 of the charge / discharge unit 100. The positive electrode current collector plate 210 is also connected to the positive electrode terminal 310. Similarly to the positive electrode current collector plate 210, the negative electrode current collector plate 220 makes electrical contact between the negative electrode 120 and the negative electrode terminal 320 of the electrode terminal 300. For example, the negative electrode current collector plate 220 includes a joint portion 222ca that is joined to the negative electrode 120 of the charge / discharge body 100. That is, the negative electrode current collector plate 220 is connected to the negative electrode 120 of the charge / discharge body 100. The negative electrode current collector plate 220 is also connected to the negative electrode terminal 320. Details of the positive electrode current collector plate 210 and the negative electrode current collector plate 220 will be described later in Figure 4.

[0018] Here, the joining of the joint portion 212ca of the positive electrode current collector plate 210 to the positive electrode 110, and the joining of the joint portion 222ca of the negative electrode current collector plate 220 to the negative electrode 120, are, for example, non-fusion joining. Examples of non-fusion joining include ultrasonic joining, friction joining, and pressure welding.

[0019] As explained in Figure 1, the electrode terminal 300 has a positive electrode terminal 310 and a negative electrode terminal 320. The electrode terminal 300 is also connected to the current collector 200. Specifically, as described above, the positive electrode terminal 310 of the electrode terminal 300 is connected to the positive electrode current collector plate 210, and the negative electrode terminal 320 of the electrode terminal 300 is connected to the negative electrode current collector plate 220. As a result, the positive electrode terminal 310 is electrically connected to the positive electrode 110 of the charge / discharge unit 100 via the positive electrode current collector plate 210, and the negative electrode terminal 320 is electrically connected to the negative electrode 120 of the charge / discharge unit 100 via the negative electrode current collector plate 220. The positive electrode terminal 310 is made of, for example, aluminum or an aluminum alloy. The negative electrode terminal 320 is made of, for example, copper or a copper alloy. Details of the positive electrode terminal 310 and the negative electrode terminal 320 will be described later in Figure 4.

[0020] As explained in Figure 1, the components of the battery 1 are housed or attached to the outer casing 400. For example, the outer casing 400 has a container 410, a lid 420, a detachable valve 430 provided on the lid 420, and a sealing plug 440.

[0021] The container 410 houses the charge / discharge unit 100, etc. For example, the container 410 is made of a rectangular metal can. The container 410 has an opening 410a that opens along the longitudinal direction X and a housing section 410b that is connected to the opening 410a. For example, the container 410 has two wide side walls 410c that are relatively large in area and face each other, two narrow side walls 410d that are relatively small in area and face each other, and a bottom section 410e that is perpendicular to the height direction Z. In the example shown in Figure 2, the two wide side walls 410c are spaced apart from each other in the short direction Y, and the two narrow side walls 410d are spaced apart from each other in the longitudinal direction X. The space partitioned by two wide side walls 410c arranged at intervals in the short direction Y, two narrow side walls 410d arranged at intervals in the long direction X, and the bottom 410e corresponds to the storage section 410b. The container 410 is made of, for example, aluminum or an aluminum alloy.

[0022] The lid 420 seals the opening 410a of the container 410. For example, the lid 420 is formed from a long, plate-shaped metal sheet. The lid 420 is made of, for example, aluminum or an aluminum alloy. Although hidden in Figure 2, the lid 420 has circular through-holes (positive electrode insertion hole 420a and negative electrode insertion hole 420b shown in Figure 4) that penetrate the lid 420 at both ends in the longitudinal direction X. Details will be described later in Figure 4, but a part of the positive electrode terminal 310 and a part of the positive electrode gasket 610 are inserted into the positive electrode insertion hole 420a, and a part of the negative electrode terminal 320 and a part of the negative electrode gasket 620 are inserted into the negative electrode insertion hole 420b. In addition, the cleavage valve 430 provided on the lid 420 cleavages outward from the battery 1 when the internal pressure of the battery 1 reaches a predetermined value, thereby reducing the internal pressure of the battery 1 to atmospheric pressure. Furthermore, the sealing plug 440 seals the liquid injection hole 420c of the lid 420 shown in Figure 7. Details of the cleavage valve 430 and the sealing plug 440 will be described later in Figure 7.

[0023] The insulator 500 insulates the components of the battery 1 from the outer casing 400. For example, the insulator 500 has an insulating cover 510. Furthermore, the insulator 500 has a positive electrode insulating plate 520 and a negative electrode insulating plate 530 as shown in Figure 4. Details of the positive electrode insulating plate 520 and the negative electrode insulating plate 530 will be described later in Figure 4. The insulating cover 510 covers the charge / discharge unit 100. However, the insulating cover 510 exposes the upper part of the charge / discharge unit 100 (in the direction indicated by the Z-axis arrow in Figure 2) to the outside. That is, the insulating cover 510 covers the part of the charge / discharge unit 100 excluding the upper part. For example, the insulating cover 510 has one bottom surface and four sides and is constructed by folding into a box shape. The insulating cover 510 is made of, for example, polypropylene.

[0024] The sealing body 600 seals the components of the battery 1 and the outer casing 400. For example, as explained in Figure 1, the sealing body 600 has a positive electrode gasket 610 and a negative electrode gasket 620. Details of the positive electrode gasket 610 and the negative electrode gasket 620 will be described later in Figure 4.

[0025] Figure 3 is a perspective view showing the charge / discharge unit 100 of Figure 2. Note that Figure 3 shows a partially unfolded state of the charge / discharge unit 100 before the current collector 200 is joined to it.

[0026] As shown in Figure 3, the charge / discharge body 100 is constructed by winding together components, each consisting of a positive electrode 110, a separator 130, a negative electrode 120, and another separator 130, in that order, into a rectangular shape.

[0027] For example, the positive electrode active material layer 112 is bonded to both sides of the positive electrode current collector layer 111. In Figure 3, the leader lines pointing to the positive electrode active material layer 112 that is hidden by the positive electrode current collector layer 111 in Figure 3 are shown as dashed lines. The positive electrode 110 is wound together with the negative electrode 120 and the separator 130 to form a rectangular prism shape with each end in the height direction Z curved in a convex shape. One side 111a of the positive electrode current collector layer 111 is not covered by the positive electrode active material layer 112 and is exposed to the outside. In the example shown in Figure 3, one side 111a of the positive electrode current collector layer 111 is the side opposite to the longitudinal direction X (the direction indicated by the arrow on the X axis) of the positive electrode current collector layer 111. Also, the positive electrode active material layer 112 is not bonded to the side 111a. As shown in Figure 2, the central portion of the side portion 111a is compressed along the short direction Y of the battery 1 when bundled. The side portion 111a is then joined to the positive electrode current collector plate 210.

[0028] As described above, the positive electrode active material layer 112 is bonded to the portion of the positive electrode current collector layer 111 excluding the side portion 111a. The positive electrode current collector layer 111 is formed of, for example, aluminum or an aluminum alloy. The positive electrode active material layer 112 is formed of a plurality of positive electrode mixture layers 11p, which will be described later. The positive electrode active material layer 112 will be described later in Figures 8 and 9.

[0029] Although Figure 3 illustrates a case where the positive electrode active material layer 112 is bonded to both sides of the positive electrode current collector layer 111, the positive electrode active material layer 112 may be bonded to only one side of the positive electrode current collector layer 111. In other words, the positive electrode 110 may be configured such that the positive electrode active material layer 112 is bonded to only one side of the positive electrode current collector layer 111.

[0030] The negative electrode 120 has a long negative electrode current collector layer 121 and a negative electrode active material layer 122 bonded to the negative electrode current collector layer 121. For example, the negative electrode active material layer 122 is bonded to both sides of the negative electrode current collector layer 121. In Figure 3, the leader lines pointing to the negative electrode active material layer 122 that is hidden by the negative electrode current collector layer 121 in Figure 3 are shown as dashed lines. The negative electrode 120 is wound together with the positive electrode 110 and the separator 130 to form a rectangular prism shape with each end in the height direction Z curved in a convex shape. One side 121a of the negative electrode current collector layer 121 is not covered by the negative electrode active material layer 122 and is exposed to the outside. In the example shown in Figure 3, one side 121a of the negative electrode current collector layer 121 is the side in the longitudinal direction X (direction indicated by the arrow on the X axis) of the negative electrode current collector layer 121. That is, the side of the charge / discharge body 100 in the longitudinal direction X corresponds to the side 121a of the negative electrode current collector layer 121, and the side of the charge / discharge body 100 in the opposite direction of the longitudinal direction X corresponds to the side 111a of the positive electrode current collector layer 111. Thus, the side 121a of the negative electrode current collector layer 121 is located in the longitudinal direction X relative to the side 111a of the positive electrode current collector layer 111 and faces the side 111a. Furthermore, the negative electrode active material layer 122 is not bonded to the side 121a. The central portion of the side 121a is compressed along the short direction Y of the battery 1 when bundled, as shown in Figure 2. The side portion 121a is then joined to the negative electrode current collector plate 220.

[0031] As described above, the negative electrode active material layer 122 is bonded to the portion of the negative electrode current collector layer 121 excluding the side portion 121a. The negative electrode current collector layer 121 is formed of, for example, copper or a copper alloy. The negative electrode active material layer 122 is formed of a plurality of negative electrode mixture layers 12m, which will be described later. The negative electrode active material layer 122 will be described later in Figures 8 and 9.

[0032] Although Figure 3 illustrates a case where the negative electrode active material layer 122 is bonded to both sides of the negative electrode current collector layer 121, the negative electrode active material layer 122 may be bonded to only one side of the negative electrode current collector layer 121. In other words, the negative electrode 120 may be configured such that the negative electrode active material layer 122 is bonded to only one side of the negative electrode current collector layer 121.

[0033] The separator 130 insulates the positive electrode 110 and the negative electrode 120 while allowing lithium ions to pass through. The separator 130 is formed in a long, rectangular shape. The separator 130 is made of, for example, a porous material. The shape of the separator 130 will be described later in Figure 9.

[0034] Here, although not specifically shown in Figure 3, the electrolyte 140 shown in Figures 5 and 6 is injected into the container 410 containing the charge / discharge unit 100, etc. The electrolyte 140 facilitates the flow of lithium ions between the positive electrode 110 and the negative electrode 120. The electrolyte 140 is also called an electrolyte solution. The electrolyte 140 contains a solvent and a solute. Additives may also be included in the electrolyte 140. The solvent may include, for example, an organic solvent. For example, a carbonate ester such as ethylene carbonate is used as the organic solvent. For example, a lithium salt may be included as the solute. For example, lithium hexafluoride phosphate (LiPF) ６ ) is used.

[0035] Figure 4 is a disassembled perspective view showing the components surrounding the positive terminal 310 and the negative terminal 320 of battery 1.

[0036] Figure 4 shows the positive electrode current collector plate 210 and the negative electrode current collector plate 220 of the current collector 200, the positive electrode terminal 310 and the negative electrode terminal 320 of the electrode terminal 300, the cover 420 of the outer casing 400, the positive electrode insulating plate 520 and the negative electrode insulating plate 530 of the insulator 500, and the positive electrode gasket 610 and the negative electrode gasket 620 of the sealing body 600.

[0037] The positive electrode current collector plate 210 has a base portion 211 and a current collector portion 212. The base portion 211 is formed in a plate shape. The base portion 211 also has an insertion hole 211a, which is a circular through-hole that penetrates the base portion 211. The current collector portion 212 is joined to the side portion 111a of the positive electrode 110 of the charge / discharge body 100 by, for example, non-melt bonding. The current collector portion 212 is formed by bending downward from the outer edge of the base portion 211 (in the opposite direction to the direction indicated by the Z-axis arrow in Figure 4). For example, the current collector portion 212 is formed integrally with the base portion 211. Also, the current collector portion 212 is formed to match the outer shape of the side portion 111a of the positive electrode 110. For example, the current collector portion 212 extends perpendicular to the base portion 211. Note that "perpendicular" includes not only strict perpendicularity but also substantial perpendicularity (for example, perpendicularity within the margin of error). Furthermore, the current collector 212 is bent in the opposite direction to the short direction Y (the direction indicated by the Y-axis arrow in Figure 4), following the outer shape of the side portion 111a of the positive electrode 110. In the example shown in Figure 4, the current collector 212 has an extended portion 212a connected to the base portion 211, an inclined portion 212b connected to the extended portion 212a, a positive electrode connection portion 212c connected to the inclined portion 212b, and an inclined portion 212d connected to the positive electrode connection portion 212c. The extended portion 212a is, for example, connected to the outer edge of the base portion 211 and extends perpendicular to the base portion 211. The inclined portion 212b is, for example, connected to the lower end of the extended portion 212a and is bent in the opposite direction to the short direction Y, following the outer shape of the side portion 111a of the positive electrode 110. The positive electrode connection portion 212c is, for example, connected to the lower end of the inclined portion 212b and is formed to face the central portion of the side portion 111a of the positive electrode 110 (the portion where the bundled positive electrode 110 is compressed along the short direction Y). A joining portion 212ca, which is a part of the positive electrode connection portion 212c, is joined to the side portion 111a of the positive electrode 110 by non-fusion bonding. The inclined portion 212d is, for example, connected to the lower end of the positive electrode connection portion 212c and is bent toward the short direction Y along the outer shape of the side portion 111a of the positive electrode 110. The positive electrode current collector plate 210 is formed of, for example, aluminum or an aluminum alloy.

[0038] The negative electrode current collector plate 220 is formed in the same manner as the positive electrode current collector plate 210. For example, the external shape of the negative electrode current collector plate 220 is symmetrical to the external shape of the positive electrode current collector plate 210 along the longitudinal direction X. The negative electrode current collector plate 220 has a base portion 221 and a current collector portion 222. The base portion 221 is formed in a plate shape. The base portion 221 also has an insertion hole 221a, which is a circular through-hole that penetrates the base portion 221. The current collector portion 222 is joined to the side portion 121a of the negative electrode 120 of the charge / discharge body 100 by, for example, non-melt joining. The current collector portion 222 is formed by bending downward from the outer edge of the base portion 221. For example, the current collector portion 222 is formed integrally with the base portion 221. Furthermore, the current collector portion 222, like the current collector portion 212 of the positive electrode current collector plate 210, is formed to match the external shape of the side portion 121a of the negative electrode 120. For example, the current collector portion 222 extends perpendicularly to the base portion 221. Also, the current collector portion 222 is bent in the opposite direction to the short direction Y, for example, along the external shape of the side portion 121a of the negative electrode 120. In the example shown in Figure 5, the current collector portion 222 has an extended portion 222a connected to the base portion 221, an inclined portion 222b connected to the extended portion 222a, a negative electrode connection portion 222c connected to the inclined portion 222b, and an inclined portion 222d connected to the negative electrode connection portion 222c. The extended portion 222a is, for example, connected to the outer edge of the base portion 221 and extends perpendicularly to the base portion 221. The inclined portion 222b is, for example, connected to the lower end of the extended portion 222a and is bent in the opposite direction to the short direction Y, following the outer shape of the side portion 121a of the negative electrode 120. The negative electrode connection portion 222c is, for example, connected to the lower end of the inclined portion 222b and is formed to face the central portion of the side portion 121a of the negative electrode 120 (the portion where the bundled negative electrode 120 is compressed along the short direction Y). A joint portion 222ca, which is a part of the negative electrode connection portion 222c, is joined to the side portion 121a of the negative electrode 120 by non-fuss bonding. The inclined portion 222d is, for example, connected to the lower end of the negative electrode connection portion 222c and is bent in the short direction Y, following the outer shape of the side portion 121a of the negative electrode 120. The negative electrode current collector plate 220 is made of, for example, copper or a copper alloy.

[0039] The positive terminal 310 has a rectangular plate-shaped base 311, a cylindrical insertion portion 312 protruding downward from the base 311, and a cylindrical joint portion 313 protruding downward from the outer circumference of the insertion portion 312. Similarly, the negative terminal 320 includes a rectangular plate-shaped base 321, a cylindrical insertion portion 322 protruding downward from the base 321, and a cylindrical joint portion 323 protruding downward from the outer circumference of the insertion portion 322. The external shape of the negative terminal 320 is the same as that of the positive terminal 310.

[0040] The lid 420, which is an element of the outer casing 400, has circular through-holes at both ends in the longitudinal direction X, namely a positive electrode insertion hole 420a and a negative electrode insertion hole 420b, respectively. For example, the positive electrode insertion hole 420a is formed at the end of the lid 420 opposite to the longitudinal direction X (the direction indicated by the arrow on the X axis in Figure 5), and the negative electrode insertion hole 420b is formed at the end in the longitudinal direction X. The insertion portion 312 of the positive electrode terminal 310 and the insertion portion 612 of the positive electrode gasket 610, which will be described later, are inserted into the positive electrode insertion hole 420a. The insertion portion 322 of the negative electrode terminal 320 and the insertion portion 622 of the negative electrode gasket 620, which will be described later, are inserted into the negative electrode insertion hole 420b.

[0041] The positive electrode insulating plate 520, which is an element of the insulator 500, insulates the positive electrode current collector plate 210 from the lid 420. For example, the positive electrode insulating plate 520 has a rectangular plate-shaped base portion 521 and an edge portion 522 that surrounds the base portion 521 in an annular shape and protrudes away from the lid 420. The base portion 211 of the positive electrode current collector plate 210 is housed in the space partitioned by the base portion 521 and the edge portion 522 of the positive electrode insulating plate 520. A circular through-hole 521a is formed in the base portion 521 of the positive electrode insulating plate 520, penetrating the base portion 521. The insertion portion 312 of the positive electrode terminal 310 and the insertion portion 612 of the positive electrode gasket 610 are inserted into the through-hole 521a of the base portion 521. The positive electrode insulating plate 520 is formed of, for example, an insulating resin.

[0042] The negative electrode insulating plate 530 insulates the negative electrode current collector plate 220 from the cover 420. The negative electrode insulating plate 530 is formed in the same way as the positive electrode insulating plate 520. For example, the negative electrode insulating plate 530 has a rectangular plate-shaped base portion 531 and an edge portion 532 that surrounds the base portion 531 in an annular shape and protrudes away from the cover 420. The base portion 221 of the negative electrode current collector plate 220 is housed in the space partitioned by the base portion 531 and the edge portion 532 of the negative electrode insulating plate 530. A circular through-hole 531a is formed in the base portion 531 of the negative electrode insulating plate 530, penetrating the base portion 531. The insertion portion 322 of the negative electrode terminal 320 and the insertion portion 622 of the negative electrode gasket 620 are inserted into the through-hole 531a of the base portion 531. The negative electrode insulating plate 530 is formed of, for example, an insulating resin.

[0043] The positive electrode gasket 610 seals the positive electrode terminal 310 and the cover 420 by being compressed by the positive electrode terminal 310 and the cover 420. The positive electrode gasket 610 has a rectangular plate-shaped base portion 611 and a cylindrical insertion portion 612 that protrudes inward from the central part of the base portion 611 into the battery 1 (in the opposite direction to the direction indicated by the Z-axis arrow in Figure 4). Furthermore, the positive electrode gasket 610 has an edge portion 613 that surrounds the base portion 611 in an annular shape and protrudes outward from the battery 1 (in the direction indicated by the Z-axis arrow in Figure 4). The base portion 611 has a through hole formed through it. For example, the cylindrical insertion portion 612 is connected to the through hole in the base portion 611. The space enclosed by the inner circumferential surface of the cylindrical insertion portion 612 and the through hole in the base portion 611 connect to each other, forming a single space (hereinafter also referred to as the through hole of the positive electrode gasket 610). The base portion 311 of the positive electrode terminal 310 is housed in the space partitioned by the base portion 611 and the edge portion 613 of the positive electrode gasket 610. The positive electrode gasket 610 is formed, for example, from an insulating resin that has insulating and elastic properties.

[0044] The negative electrode gasket 620 is also formed in the same manner as the positive electrode gasket 610. For example, the negative electrode gasket 620 seals between the negative electrode terminal 320 and the lid 420 by being compressed by the negative electrode terminal 320 and the lid 420. The outer shape of the negative electrode gasket 620 is the same as the outer shape of the positive electrode gasket 610. For example, the negative electrode gasket 620 includes a rectangular plate-shaped base portion 621, and a cylindrical insertion portion 622 protruding inward of the battery 1 from the central portion of the base portion 621. Furthermore, the negative electrode gasket 620 has an edge portion 623 that annularly surrounds the base portion 621 and protrudes outward of the battery 1. A through-hole penetrating the base portion 621 is formed in the base portion 621. For example, the cylindrical insertion portion 622 is continuous with the through-hole of the base portion 621. A space surrounded by the inner peripheral surface of the cylindrical insertion portion 622 and the through-hole of the base portion 621 are connected to each other, thereby forming one space (hereinafter also referred to as the through-hole of the negative electrode gasket 620). The base portion 321 of the negative electrode terminal 320 is accommodated in a space defined by the base portion 621 and the edge portion 623 of the negative electrode gasket 620. The negative electrode gasket 620 is formed of, for example, an insulating resin having insulating properties and elasticity.

[0045] Figure 5 is a side view cross-sectionally showing constituent members around the positive electrode terminal 310 of the battery 1. Figure 5 shows a cross-section of the battery 1 taken along line A1-A2 in Figure 1, as a cross-section around the positive electrode terminal 310.

[0046] In addition to the base portion 311, insertion portion 312, and joint portion 313 shown in FIG. 4, the positive electrode terminal 310 has a sealing portion 314 formed in an annular shape at the boundary between the base portion 311 and the insertion portion 312. The base portion 311 is provided on a base portion 611 of the positive electrode gasket 610. The insertion portion 312 is inserted into a through hole of the positive electrode gasket 610 (a space where the through hole of the base portion 611 and a space surrounded by the inner circumferential surface of the insertion portion 612 communicate with each other). The joint portion 313 protrudes downward (in a direction opposite to the direction indicated by the arrow of the Z-axis in FIG. 5) from an insertion hole 211a of a base portion 211 of the positive electrode current collector plate 210. The protruding portion of the joint portion 313 is spread outward in the radial direction and joined to the base portion 211. For example, the joint portion 313 is crimped to the base portion 211. Furthermore, the joint portion 313 is welded to the base portion 211. As described above, the joint portion 313 is joined to the base portion 211. In addition, the sealing portion 314 is a convex portion that protrudes from the base portion 311 toward the positive electrode gasket 610. The sealing portion 314, together with the lid 420, partially compresses the base portion 611 of the positive electrode gasket 610 along the height direction Z. Thereby, the positive electrode terminal 310 and the lid 420 are sealed via the positive electrode gasket 610. It should be noted that the positive electrode current collector plate 210 and the lid 420 are insulated by a positive electrode insulating plate 520.

[0047] As described above, the joint portion 313 of the positive electrode terminal 310 is inserted into the insertion hole 211a of the base portion 211 of the positive electrode current collector plate 210. Then, as described above, the base portion 211 is joined to the joint portion 313 by crimping the joint portion 313.

[0048] Furthermore, the insertion portion 612 of the positive electrode gasket 610 is inserted into a positive electrode insertion hole 420a of the lid 420. As described above, the insertion portion 312 of the positive electrode terminal 310 is inserted into the through hole of the base portion 611 of the positive electrode gasket 610 and the space surrounded by the inner circumferential surface of the insertion portion 612.

[0049] FIG. 6 is a side cross-sectional view of constituent members around the negative electrode terminal 320 of the battery 1. FIG. 6 shows a cross-section of the battery 1 taken along line B1-B2 in FIG. 1 as a cross-section around the negative electrode terminal 320.

[0050] The negative electrode terminal 320 has a base portion 321, an insertion portion 322, and a joint portion 323 as shown in Figure 4, as well as a sealing portion 324 formed in an annular shape at the boundary between the base portion 321 and the insertion portion 322. The base portion 321 is provided on the base portion 621 of the negative electrode gasket 620. The insertion portion 322 is inserted into the negative electrode gasket 620 (the space formed by the connection between the through hole of the base portion 621 and the space surrounded by the inner circumferential surface of the cylindrical insertion portion 622). The joint portion 323 protrudes downward (in the opposite direction to the direction indicated by the Z-axis arrow in Figure 6) from the insertion hole 221a of the base portion 221 of the negative electrode current collector plate 220. The protruding portion of the joint portion 323 is pushed outward radially and joined to the base portion 221. For example, the joint portion 323 is crimped to the base portion 221. Furthermore, the joint portion 323 is welded to the base portion 221. In this way, the joint portion 323 is joined to the base portion 221. The sealing portion 324 is a protrusion that extends from the base portion 321 toward the negative electrode gasket 620. Together with the lid 420, the sealing portion 324 partially compresses the base portion 621 of the negative electrode gasket 620 along the height direction Z. As a result, the negative electrode terminal 320 and the lid 420 are sealed together via the negative electrode gasket 620. The negative electrode current collector plate 220 and the lid 420 are insulated from each other by the negative electrode insulating plate 530.

[0051] As described above, the connecting portion 323 of the negative electrode terminal 320 is inserted into the insertion hole 221a of the base portion 221 of the negative electrode current collector plate 220. The base portion 221 is then joined to the connecting portion 323 by crimping the connecting portion 323.

[0052] Furthermore, the insertion portion 622 of the negative electrode gasket 620 is inserted into the negative electrode insertion hole 420b of the lid 420. As described above, the insertion portion 322 of the negative electrode terminal 320 is inserted into the space surrounded by the through hole in the base portion 621 of the negative electrode gasket 620 and the inner circumferential surface of the insertion portion 622.

[0053] Figure 7 is a disassembled perspective view showing the components surrounding the cleavage valve 430 and sealing plug 440 of the battery 1. As already described, the outer casing 400 includes a container 410, a lid 420, a cleavage valve 430, and a sealing plug 440.

[0054] The cleavage valve 430 is provided on the lid 420. For example, the cleavage valve 430 is formed integrally with the lid 420. The cleavage valve 430 is formed in an elliptical shape, for example. Also, the cleavage valve 430 is formed to be thinner than the lid 420. The cleavage valve 430 has a groove that serves as a reference for cleavage. For example, as explained in Figure 2, when the internal pressure of the battery 1 reaches a predetermined value, the cleavage valve 430 cleaves outward from the battery 1 to reduce the internal pressure of the battery 1 to atmospheric pressure. Note that the cleavage valve 430 does not have to be formed integrally with the lid 420. For example, the cleavage valve 430 may be formed separately from the lid 420 and then welded in an annular manner to a through hole provided in the lid 420.

[0055] The sealing plug 440 seals the liquid injection insertion hole 420c formed in the lid 420. The liquid injection insertion hole 420c is a circular through-hole formed between the positive electrode insertion hole 420a and the negative electrode insertion hole 420b of the lid 420. The insertion portion 440b of the sealing plug 440, described later, is inserted into the liquid injection insertion hole 420c. The sealing plug 440 is formed in a cylindrical shape. For example, the sealing plug 440 has a head 440a with a relatively large outer diameter, and an insertion portion 440b with a relatively small outer diameter that is continuous with the head 440a. The head 440a of the sealing plug 440 is welded to the lid 420. The insertion portion 440b is inserted into the liquid injection insertion hole 420c as described above. The sealing plug 440 is formed of, for example, aluminum or an aluminum alloy.

[0056] (Regarding dendrite formation) If the thickness of one or both of the positive electrode active material layer 112 and the negative electrode active material layer 122 is not uniform during the manufacturing of the positive electrode 110 and the negative electrode 120, lithium crystals may be deposited. The deposited lithium crystals may grow as dendritic crystals, or so-called dendrites. Dendrites are more likely to form on the positive electrode 110. When dendrites grow, a short circuit may occur between the positive electrode 110 and the negative electrode 120 via the dendrites. If a short circuit occurs, it may cause a voltage drop. An example of dendrite growth is illustrated using Figure 8.

[0057] Figure 8 is a side view showing a cross-section of a part of the charge / discharge body 100A in a comparative configuration. The charge / discharge body 100A differs from the charge / discharge body 100 in that it has a separator 130A instead of a separator 130. In Figure 8, the charge / discharge body 100 shown in Figure 3 is replaced with the charge / discharge body 100A, and a cross-section of the charge / discharge body 100A along the line C1-C2 in Figure 3 is shown. This cross-section is a view of the components stacked in the order of positive electrode 110, separator 130A, negative electrode 120, and separator 130A, when the charge / discharge body 100A is not unfolded, viewed in the opposite direction of the height Z.

[0058] The positive electrode active material layer 112 is formed by a first positive electrode mixture layer 11p1 and a second positive electrode mixture layer 11p2. The first positive electrode mixture layer 11p1 is laminated on the positive electrode current collector layer 111. The second positive electrode mixture layer 11p2 is laminated on the first positive electrode mixture layer 11p1. Hereinafter, the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2 may be referred to simply as the positive electrode mixture layer 11p. The positive electrode mixture layer 11p contains a positive electrode active material composed of a lithium-containing composite oxide, a binder, and a conductive additive. Examples of lithium-containing composite oxides include metallic elements such as nickel (Ni), cobalt (Co), and manganese (Mn), and lithium (Li). The component ratios of the first cathode mixture layer 11p1 and the component ratios of the second cathode mixture layer 11p2 are different from each other. Alternatively, the particle sizes of each component in the first cathode mixture layer 11p1 and the particle sizes of each component in the second cathode mixture layer 11p2 may be different from each other. An example of different component ratios is when the proportion of nickel in the first cathode mixture layer 11p1 is higher than the proportion of nickel in the second cathode mixture layer 11p2. Furthermore, when the proportion of cobalt in the second cathode mixture layer 11p2 is higher than the proportion of cobalt in the first cathode mixture layer 11p1.

[0059] The negative electrode active material layer 122 is formed by a first negative electrode mixture layer 12m1 and a second negative electrode mixture layer 12m2. The first negative electrode mixture layer 12m1 is laminated on the negative electrode current collector layer 121. The second negative electrode mixture layer 12m2 is laminated on the first negative electrode mixture layer 12m1. Hereinafter, the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2 may be referred to simply as the negative electrode mixture layer 12m. The negative electrode mixture layer 12m contains a negative electrode active material, a binder, and a conductive additive, etc., all composed of carbon-based materials. For example, graphite is used as the carbon-based material. The component ratios of the first negative electrode mixture layer 12m1 and the component ratios of the second negative electrode mixture layer 12m2 are different from each other. Alternatively, the particle sizes of each component in the first negative electrode mixture layer 12m1 and the particle sizes of each component in the second negative electrode mixture layer 12m2 may differ from each other. An example of differing particle sizes is that the graphite particles contained in the first negative electrode mixture layer 12m1 are smaller than the graphite particles contained in the second negative electrode mixture layer 12m2.

[0060] The manufacturer of battery 1 can produce a battery 1 with desired performance by appropriately combining two positive electrode mixture layers 11p and two negative electrode mixture layers 12m. For example, increasing the proportion of nickel in one or both of the two positive electrode mixture layers 11p can produce a battery 1 with increased capacity. Alternatively, increasing the proportion of cobalt in one or both of the two positive electrode mixture layers 11p can produce a battery 1 with improved output characteristics.

[0061] However, the inventors have discovered that if the balance of the thicknesses of the two positive electrode mixture layers 11p and the two negative electrode mixture layers 12m is disrupted, dendrites will form on one or both of the positive electrode mixture layers 11p and the positive electrode current collector layer 111. A disruption in thickness balance means that, when the charge / discharge body 100 is viewed in the short direction Y, the thicknesses of the two positive electrode mixture layers 11p and the two negative electrode mixture layers 12m in localized areas deviate from the thicknesses assumed by the manufacturer of the battery 1. Two factors, for example, can cause this disruption in thickness balance.

[0062] The first factor is that in one or more of the two positive electrode mixture layers 11p and the two negative electrode mixture layers 12m, the side surface facing the longitudinal direction X, which is perpendicular to the short direction Y, is formed to be inclined with respect to the short direction Y. Figure 8 shows an example in which the side surface 122a facing the longitudinal direction X of the negative electrode active material layer 122, which is bonded to the side surface of the negative electrode current collector layer 121 facing the opposite direction of the short direction Y, is formed to be inclined with respect to the short direction Y. When the side surface of the negative electrode active material layer 122 facing the longitudinal direction X is inclined with respect to the short direction Y, the balance of thickness is disrupted because there is no positive electrode active material layer 112 corresponding to this inclined portion.

[0063] The second factor is that the manufacturing method for producing the two positive electrode mixture layers 11p and the two negative electrode mixture layers 12m can result in a raised structure at the edges of the positive electrode mixture layer 11p. In Figure 8, a protrusion 11CP is formed at the longitudinal X end of the second positive electrode mixture layer 11p2, which is laminated on the surface of the positive electrode current collector layer 111 facing the short direction Y. The reason why the protrusion 11CP is formed is that, depending on the manufacturing method for the positive electrode mixture layer 11p, the thickness of the positive electrode mixture layer 11p may not be uniform. For example, there is a manufacturing method in which the material of the positive electrode mixture layer 11p is a liquid, and this liquid is coated onto the positive electrode current collector layer 111 to produce the positive electrode mixture layer 11p. In this manufacturing method, the properties of the liquid can result in a raised structure at the edges of the positive electrode mixture layer 11p. Furthermore, in this manufacturing method, a step is performed in which a liquid is coated onto the positive electrode current collector layer 111 and then pressed. However, even after pressing, the thickness of the positive electrode mixture layer 11p may not be completely uniform.

[0064] Figure 8 shows the state in which dendrites 11DE are formed due to the first factor. The dendrites 11DE grow in the direction of the shorter side Y. When the dendrites 11DE come into contact with the negative electrode active material layer 122 or the negative electrode current collector layer 121, a short circuit occurs between the positive electrode 110 and the negative electrode 120 via the dendrites 11DE.

[0065] Therefore, in this embodiment, the objective is to suppress short circuits between the positive electrode 110 and the negative electrode 120 even if dendrites 11DE are formed. The charge / discharge body 100 of this embodiment will be explained with reference to Figure 9.

[0066] Figure 9 is a side view showing a cross-section of a part of the charge / discharge body 100. Figure 9 shows a cross-section of the charge / discharge body 100 along the line C1-C2 in Figure 3, with the charge / discharge body 100 not yet unfolded. This cross-section is a view of the components stacked in the order of positive electrode 110, separator 130, negative electrode 120, and separator 130, in the opposite direction of the height Z.

[0067] The negative electrode current collector layer 121 is divided into a side portion 121a and a laminated portion 121b in which one or both of the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2 are laminated. The side portion 121a can also be described as an exposed portion in which the negative electrode current collector layer 121 is exposed. The side portion 121a is located closer to the end 121p in the longitudinal direction X of the negative electrode current collector layer 121 than the laminated portion 121b. The longitudinal direction X can also be described as the direction along the winding axis in which the charge / discharge body 100 is wound.

[0068] As shown in Figure 9, the separator 130 has an adhesive portion 130a that adheres to the second negative electrode mixture layer 12m2 and a contact portion 130b that contacts the side portion 121a. The adhesive portion 130a may be bonded to the second negative electrode mixture layer 12m2 by pressure contact, or it may be bonded to the second negative electrode mixture layer 12m2 via an adhesive. The contact portion 130b extends along the height direction Z, which is the extending direction of the side portion 121a. The contact portion 130b may contact the side portion 121a by pressure contact, or it may contact the side portion 121a via an adhesive. The contact portion 130b only needs to contact a part of the side portion 121a.

[0069] Furthermore, the separator 130 has a connecting portion 130c between the adhesive portion 130a and the contact portion 130b, which connects the adhesive portion 130a and the contact portion 130b. In the example of Figure 9, the connecting portion 130c contacts the side surface 122a of the second negative electrode mixture layer 12m2 and the first negative electrode mixture layer 12m1 facing the longitudinal direction X. The connecting portion 130c may contact the side surface 122a by pressure contact, may contact the side surface 122a via adhesive, or may simply be in contact with the side surface 122a. The short direction Y is the direction in which the negative electrode 120 and the positive electrode 110 are stacked, and the longitudinal direction X is the direction intersecting the short direction Y, and is an example of the "first direction".

[0070] Furthermore, it is preferable that the separator 130 has aramid fibers. For example, the separator 130 is formed from aramid fibers and a small amount of adhesive. Aramid fibers are porous resins and have heat resistance. The melting point of aramid fibers is about 400 degrees Celsius. However, the separator 130 does not have to have aramid fibers. For example, the separator 130 may be made of polyethylene (PE) or polypropylene (PP).

[0071] As shown in Figure 9, the end 122p in the longitudinal direction X of the negative electrode active material layer 122 is located closer to the end 121p in the longitudinal direction X of the negative electrode current collector layer 121 than the end 112p in the longitudinal direction X of the positive electrode active material layer 112.

[0072] Although not shown in Figure 9, the second positive electrode mixture layer 11p2 may have an adhesive or insulating layer on the surface facing the separator 130. Similarly, the second negative electrode mixture layer 12m2 may have an adhesive or insulating layer on the surface facing the separator 130.

[0073] In the first embodiment, the charge / discharge body 100 has two separators 130, but one of the two separators 130 may be separator 130A.

[0074] The positive electrode active material layer 112 has a first positive electrode mixture layer 11p1 and a second positive electrode mixture layer 11p2, but it may also have a positive electrode mixture layer between the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2 that is different from the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2. Alternatively, the positive electrode active material layer 112 may have a layer other than the positive electrode mixture layer, such as an adhesive layer, between the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2. Similarly, the negative electrode active material layer 122 has a first negative electrode mixture layer 12m1 and a second negative electrode mixture layer 12m2, but it may also have a negative electrode mixture layer between the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2 that is different from the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2. Alternatively, the negative electrode active material layer 122 may have a layer other than the negative electrode mixture layer, such as an adhesive layer, between the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2.

[0075] In the first embodiment, the negative electrode 120 is an example of a "first electrode," and the positive electrode 110 is an example of a "second electrode." The negative electrode current collector layer 121 is an example of a "first electrode base," and the negative electrode active material layer 122 is an example of a "first active material layer." The positive electrode current collector layer 111 is an example of a "second electrode base," and the positive electrode active material layer 112 is an example of a "second active material layer." The first negative electrode composite layer 12m1 is an example of a "first composite layer," and the second negative electrode composite layer 12m2 is an example of a "second composite layer."

[0076] (Effects of Battery 1 in the First Embodiment) The effects of Battery 1 in the first embodiment will be described below.

[0077] As described above, in the first embodiment, the battery 1 has a negative electrode 120, a positive electrode 110, and a separator 130 provided between the negative electrode 120 and the positive electrode 110. The negative electrode 120 has a negative electrode current collector layer 121 and a negative electrode active material layer 122 laminated on the negative electrode current collector layer 121. The positive electrode 110 has a positive electrode current collector layer 111 and a positive electrode active material layer 112 laminated on the positive electrode current collector layer 111. The negative electrode active material layer 122 has a first negative electrode mixture layer 12m1 laminated on the negative electrode current collector layer 121 and a second negative electrode mixture layer 12m2 laminated on the first negative electrode mixture layer 12m1. The negative electrode current collector layer 121 is divided into a laminated portion 121b in which one or both of the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2 are laminated, and a side portion 121a which is an exposed portion where the negative electrode current collector layer 121 is exposed. The separator 130 has an adhesive portion 130a that adheres to the second negative electrode mixture layer 12m2 and a contact portion 130b that comes into contact with the side portion 121a.

[0078] In the first embodiment, the contact portion 130b acts as a barrier to prevent the dendrite from coming into contact with the negative electrode current collector layer 121 or the negative electrode active material layer 122, thereby preventing a short circuit between the positive electrode 110 and the negative electrode 120.

[0079] Furthermore, it is preferable that the separator 130 has aramid fibers.

[0080] Contact between the dendrite and the negative electrode current collector layer 121 or the negative electrode active material layer 122 is suppressed by the separator 130, but the dendrite may penetrate the separator 130, causing a localized short circuit between the positive electrode 110 and the negative electrode 120. When the positive electrode 110 and the negative electrode 120 are short-circuited, heat is generated, and if the separator 130 does not have heat resistance, the heat may cause the through-hole in the separator 130 to enlarge. If the through-hole enlarges, the short-circuited area will also enlarge. In the first embodiment, even if the dendrite penetrates the separator 130, the heat resistance of the aramid fiber can suppress the enlargement of the through-hole, thus preventing the short-circuited area from enlargeing.

[0081] Furthermore, the separator 130 has a connecting portion 130c that connects the adhesive portion 130a and the contact portion 130b. The connecting portion 130c contacts the side surfaces 122a of the first negative electrode mixture layer 12m1 and the second negative electrode mixture layer 12m2 that face the longitudinal direction X. The longitudinal direction X is the direction that intersects the direction in which the negative electrode 120 and the positive electrode 110 are stacked.

[0082] By having the contact portion 130c contact the side surface 122a, the inclusion of foreign matter between the negative electrode active material layer 122 and the separator 130 can be suppressed compared to the configuration in which the contact portion 130c does not contact the side surface 122a. Furthermore, by having the contact portion 130c contact the side surface 122a, in the example of Figure 9, the contact portion 130b can be brought closer to the negative electrode active material layer 122, thereby shortening the length of the charge / discharge body 100 in the longitudinal direction X. Alternatively, if the length of the charge / discharge body 100 in the longitudinal direction X is maintained, the length of the negative electrode active material layer 122 in the longitudinal direction X can be increased, thereby increasing the battery capacity.

[0083] (Configuration of Battery 2 in the Second Embodiment) The configuration of Battery 2 in the second embodiment will be described with reference to Figure 10. Figure 10 is a side view showing a part of the charge / discharge body 101 in the second embodiment in cross-section. Battery 2 differs from Battery 1 in that it has a charge / discharge body 101 instead of a charge / discharge body 100. The charge / discharge body 101 differs from the charge / discharge body 100 in that it has a separator 130A and a separator 131 in the second embodiment instead of two separators 130. Figure 10 shows a cross-section of the charge / discharge body 101 along the line C1-C2 in Figure 3, with the charge / discharge body 101 not unfolded. This cross-section is a view of the components stacked in the order of positive electrode 110, separator 131, negative electrode 120, and separator 130A, in the opposite direction of the height Z.

[0084] The positive electrode current collector layer 111 is divided into a side portion 111a and a laminated portion 111b in which one or both of the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2 are laminated. The side portion 111a can also be described as an exposed portion in which the positive electrode current collector layer 111 is exposed. It is located closer to the end 111q in the direction opposite to the longitudinal direction X of the positive electrode current collector layer 111 than to the laminated portion 111b.

[0085] As shown in Figure 10, the separator 131 has an adhesive portion 131a that adheres to the second positive electrode mixture layer 11p2 and a contact portion 131b that contacts the side portion 111a. The adhesive portion 131a may be bonded to the second positive electrode mixture layer 11p2 by pressure contact, or it may be bonded to the second positive electrode mixture layer 11p2 via an adhesive. The contact portion 131b extends along the height direction Z, which is the extending direction of the side portion 111a. The contact portion 131b may contact the side portion 111a by pressure contact, or it may contact the side portion 111a via an adhesive.

[0086] Furthermore, the separator 131 has a connecting portion 131c between the adhesive portion 131a and the contact portion 131b, which connects the adhesive portion 131a and the contact portion 131b. In the example of Figure 10, the connecting portion 131c contacts the side surface 112a of the second positive electrode mixture layer 11p2 and the first positive electrode mixture layer 11p1 that faces in the opposite direction of the longitudinal direction X. The connecting portion 131c may contact the side surface 112a by pressure contact, may contact the side surface 112a via adhesive, or may simply be in contact with the side surface 112a. The short direction Y is the direction in which the negative electrode 120 and the positive electrode 110 are stacked, and in the second embodiment, the direction opposite to the longitudinal direction X is the direction intersecting the short direction Y, and is an example of the "first direction".

[0087] As shown in Figure 10, the end 122q of the negative electrode active material layer 122 in the opposite direction of the longitudinal direction X is located closer to the end 111q of the positive electrode current collector layer 111 in the opposite direction of the longitudinal direction X than the end 112q of the positive electrode active material layer 112 in the opposite direction of the longitudinal direction X. When viewed in the short direction Y, the region 122r where the side portion 111a and the negative electrode active material layer 122 overlap overlaps with the contact portion 131b. In the example of Figure 10, when viewed in the short direction Y, the entire region 122r overlaps with the contact portion 131b, but a part of region 122r may overlap with the contact portion 131b. However, it is preferable that the entire region 122r overlaps with the contact portion 131b when viewed in the short direction Y.

[0088] In the second embodiment, the end of the separator 131 in the longitudinal direction X is not in contact with the side portion 121a of the negative electrode current collector layer 121, but it may be in contact as in the first embodiment.

[0089] In the second embodiment, the positive electrode 110 is an example of a "first electrode," and the negative electrode 120 is an example of a "second electrode." The positive electrode current collector layer 111 is an example of a "first electrode base," and the positive electrode active material layer 112 is an example of a "first active material layer." The negative electrode current collector layer 121 is an example of a "second electrode base," and the negative electrode active material layer 122 is an example of a "second active material layer." The first positive electrode composite layer 11p1 is an example of a "first composite layer," and the second positive electrode composite layer 11p2 is an example of a "second composite layer."

[0090] (Effects of Battery 2 in the Second Embodiment) The effects of Battery 2 in the second embodiment will be described.

[0091] As described above, the battery 2 has a positive electrode 110, a negative electrode 120, and a separator 131 provided between the positive electrode 110 and the negative electrode 120. The positive electrode 110 has a positive electrode current collector layer 111 and a positive electrode active material layer 112 laminated on the positive electrode current collector layer 111. The negative electrode 120 has a negative electrode current collector layer 121 and a negative electrode active material layer 122 laminated on the negative electrode current collector layer 121. The positive electrode active material layer 112 has a first positive electrode mixture layer 11p1 laminated on the positive electrode current collector layer 111 and a second positive electrode mixture layer 11p2 laminated on the first positive electrode mixture layer 11p1. The positive electrode current collector layer 111 is divided into a laminated portion 111b in which one or both of the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2 are laminated, and a side portion 111a which is an exposed portion where the positive electrode current collector layer 111 is exposed. The separator 131 has an adhesive portion 131a that adheres to the second positive electrode mixture layer 11p2 and a contact portion 131b that contacts the side portion 111a.

[0092] In the second embodiment, similar to the first embodiment, the contact portion 131b can prevent the dendrite from short-circuiting the positive electrode 110 and the negative electrode 120.

[0093] Furthermore, the separator 131 has a connecting portion 131c that connects the adhesive portion 131a and the contact portion 131b. The connecting portion 131c contacts the side surfaces 112a of the first positive electrode mixture layer 11p1 and the second positive electrode mixture layer 11p2 that face in opposite directions to the longitudinal direction X. The direction opposite to the longitudinal direction X is the direction that intersects the direction in which the negative electrode 120 and the positive electrode 110 are stacked.

[0094] Similar to the first embodiment, the contact portion 131c contacts the side surface 112a, which suppresses the incorporation of foreign matter between the positive electrode active material layer 112 and the separator 130 compared to the configuration in which the contact portion 131c does not contact the side surface 122a.

[0095] Furthermore, when viewed in the short direction Y, which is the direction in which the positive electrode 110 and the negative electrode 120 are stacked, the region 122r where the side portion 111a, which is the exposed portion of the positive electrode current collector layer 111, and the negative electrode active material layer 122 overlap coincides with the contact portion 131b.

[0096] In the second embodiment, when viewed in the short direction Y, region 122r is prone to dendrite formation because the balance of the thicknesses of the two positive electrode mixture layers 11p and the two negative electrode mixture layers 12m is disrupted. Therefore, the contact portion 131b acts as a barrier to prevent dendrites formed in the portion of the positive electrode current collector layer 111 that overlaps with region 122r when viewed in the short direction Y from contacting the negative electrode current collector layer 121 and the negative electrode active material layer 122, thereby preventing a short circuit between the positive electrode 110 and the negative electrode 120.

[0097] (Batteries of other embodiments) The batteries of this disclosure are not limited to the configurations of the batteries described in each of the embodiments described above, but can be configured as appropriate based on the claims.

[0098] Each of the embodiments described above has been explained in detail or in a simplified manner for the purpose of making this disclosure easy to understand, and it is not necessary to have all of the described configurations, or to have configurations that are not shown. Furthermore, some of the configurations of each of the embodiments described above may be deleted, replaced with configurations from other embodiments, or combined with configurations from other embodiments.

[0099] (First Modification) In the first embodiment, the contact portion 130c contacts the side surface 122a, but it does not have to contact the side surface 122a. The battery 3 of the first modification will be described with reference to Figure 11. Figure 11 is a side view showing a cross-section of a part of the charge / discharge body 102 in the first modification. Battery 3 differs from battery 1 in that it has a charge / discharge body 102 instead of a charge / discharge body 100. The charge / discharge body 102 differs from the charge / discharge body 100 in that it has a separator 132 instead of two separators 130. Figure 12 shows a cross-section of the charge / discharge body 102 along the line C1-C2 in Figure 3, as a view of the components stacked in the order of positive electrode 110, separator 132, negative electrode 120, and separator 130 in the opposite direction of the height Z, with the charge / discharge body 102 not deployed.

[0100] The separator 132 has an adhesive portion 132a that adheres to the second negative electrode mixture layer 12m2 and a contact portion 132b that contacts the side portion 121a. Furthermore, the separator 132 has a connecting portion 132c between the adhesive portion 132a and the contact portion 132b that connects the adhesive portion 132a and the contact portion 132b. The connecting portion 132c does not contact the side portion 122a facing the longitudinal direction X of the second negative electrode mixture layer 12m2 and the first negative electrode mixture layer 12m1.

[0101] While the first modification is based on the first embodiment, an embodiment based on the second embodiment is also possible. Specifically, the connecting portion 131c of the second embodiment does not need to come into contact with the side surface 112a.

[0102] (Second Modification) In each of the above embodiments, the separator 130 has aramid fibers, but it may also have a layer having aramid fibers and a layer having lower heat resistance than aramid fibers. The configuration of the battery 4 of the second modification will be described with reference to Figure 12. Figure 12 is a side view showing a part of the charge / discharge body 103 in the second modification in cross-section. The battery 4 differs from the battery 1 in that it has a charge / discharge body 103 instead of the charge / discharge body 100. The charge / discharge body 103 differs from the charge / discharge body 100 in that it has a separator 133 in the second modification instead of a separator 130 located in the opposite direction to the short side Y from the negative electrode current collector layer 121, and has a separator 134 instead of a separator 130 located in the short side Y from the negative electrode current collector layer 121. Figure 12 shows a cross-section of the charge / discharge body 103 along the line C1-C2 in Figure 3, as viewed in the opposite direction to the height Z of the stacked components, which consist of the positive electrode 110, separator 133, negative electrode 120, and separator 134, in the state where the charge / discharge body 103 is not unfolded.

[0103] The separator 133 has a heat-resistant layer 133a having aramid fibers and a non-heat-resistant layer 133b having lower heat resistance than the aramid fibers. The non-heat-resistant layer 133b is made of a porous material that has lower heat resistance than the aramid fibers. The non-heat-resistant layer 133b is made of, for example, polyethylene and polypropylene. As shown in Figure 12, the heat-resistant layer 133a is located between the non-heat-resistant layer 133b and the positive electrode 110.

[0104] The separator 134 has a heat-resistant layer 134a having aramid fibers and a non-heat-resistant layer 134b having lower heat resistance than the aramid fibers. As shown in Figure 12, the non-heat-resistant layer 134b is located between the heat-resistant layer 134a and the negative electrode 120. The components, which are stacked in the order of positive electrode 110, separator 132, negative electrode 120, and separator 134, are wound into a rectangular shape, so that the heat-resistant layer 134a of the separator 134 is located between the non-heat-resistant layer 134b and the positive electrode 110.

[0105] In the second modified example, the charge / discharge body 103 may have a separator 130 instead of a separator 133, or it may have a separator 130A.

[0106] The second modification is based on the first embodiment, but an embodiment based on the second embodiment is also possible.

[0107] (Third Modification) In the first embodiment and each modification based on the first embodiment, the positive electrode active material layer 112 may have one positive electrode mixture layer 11p. Similarly, in the second embodiment and each modification based on the second embodiment, the negative electrode active material layer 122 may have one negative electrode mixture layer 12p.

[0108] (Fourth Modification) The battery 1 of this disclosure is not limited to a lithium-ion battery. The battery 1 of this disclosure can be applied to, for example, a nickel-metal hydride battery or a lead-acid battery. In this modification as well, the same effects as those of the embodiments described above can be obtained.

[0109] (Fifth Modification) The battery 1 of this disclosure is not limited to a secondary battery. The battery 1 of this disclosure can be applied to a primary battery. In this modification as well, the same effects as those of each embodiment described above can be obtained.

[0110] (Sixth Modification) The battery 1 of this disclosure is not limited to a configuration in which one charge / discharge element 100 is provided. The battery 1 of this disclosure can be applied to a configuration in which two or more charge / discharge elements 100 are provided. In this modification as well, the same effects as those of the embodiments described above can be obtained.

[0111] (Seventh Modification) The battery 1 of the present disclosure is not limited to a configuration in which the charge / discharge element 100 is sealed by a container 410 and a lid 420. The battery 1 of the present disclosure can be applied to a configuration in which the charge / discharge element 100 is sealed by a laminate film. In this modification as well, the same effects as those of the embodiments described above can be obtained.

[0112] 1, 2, 3, 4 Battery, 11p1 First positive electrode mixture layer, 11p2 Second positive electrode mixture layer, 12m1 First negative electrode mixture layer, 12m2 Second negative electrode mixture layer, 100, 100A, 101, 102, 103 Charge / discharge unit, 110 Positive electrode, 111 Positive electrode current collector layer, 111a Side (exposed part), 111b Laminated part, 112 Positive electrode active material layer, 112a Side surface, 120 Negative electrode, 121 Negative electrode current collector layer, 121a Side (exposed part), 121b Laminated part, 122 Negative electrode active material layer, 122a Side surface, 122r Region, 130, 130A, 131, 132, 133, 134 Separator, 130a Adhesive part, 130b Contact portion, 130c; connecting portion, 131a; adhesive portion, 131b; contact portion, 131c; connecting portion, 132a; adhesive portion, 132b; contact portion, 132c; connecting portion; X: longitudinal direction, Y: short direction, Z: height direction.

Claims

1. A battery comprising: a first electrode which is one of a positive electrode and a negative electrode; a second electrode which is the other electrode; and a separator provided between the first electrode and the second electrode, wherein the first electrode comprises a first electrode base and a first active material layer laminated on the first electrode base; the second electrode comprises a second electrode base and a second active material layer laminated on the second electrode base; the first active material layer comprises a first compound layer laminated on the first electrode base and a second compound layer laminated on the first compound layer; the first electrode base is divided into a laminated portion where one or both of the first compound layer and the second compound layer are laminated and an exposed portion where the first electrode base is exposed; and the separator comprises an adhesive portion that adheres to the second compound layer and a contact portion that contacts the exposed portion.

2. The battery according to claim 1, wherein the separator has aramid fibers.

3. The battery according to claim 1 or 2, wherein the separator has a connecting portion that connects the adhesive portion and the contact portion, the connecting portion contacts one or both of the first mixture layer and the second mixture layer facing a first direction, and the first direction is a direction that intersects the direction in which the first electrode and the second electrode are stacked.

4. The battery according to claim 1 or 2, wherein the first electrode is the negative electrode and the second electrode is the positive electrode.

5. The battery according to claim 1 or 2, wherein the first electrode is the positive electrode, the second electrode is the negative electrode, and the region where the exposed portion and the second active material layer overlap when viewed in the direction in which the positive electrode and the negative electrode are stacked overlaps with the contact portion.

Images