JP7733697B2 - Secondary battery manufacturing method - Google Patents

Description

This technology relates to secondary batteries and manufacturing methods thereof.

Japanese Patent No. 4537353 (Patent Document 1) shows a rectangular secondary battery in which an electrode group (25) is housed in a case (14) having openings (14a, 14b) at both ends, and electrode terminals (21, 23) are attached to cap plates (33, 33') that seal the openings (14a, 14b).

Furthermore, Japanese Patent Application Laid-Open No. 2021-048141 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2016-103425 (Patent Document 3) disclose a method in which the separator interposed between the positive and negative electrode plates is folded zigzag and the separator is arranged to surround the outer periphery of the stack of positive and negative electrode plates.

Patent No. 4537353 Japanese Patent Application Laid-Open No. 2021-048141 JP 2016-103425 A

It is necessary to efficiently house the electrode assembly in a case while minimizing damage to the laminated electrode assembly, which consists of stacked positive and negative electrode plates.

The purpose of this technology is to provide a secondary battery and a manufacturing method thereof that can meet these demands.

This technology provides the following secondary batteries and manufacturing methods:

[1] A secondary battery comprising: a laminated electrode assembly in which multiple positive electrode plates and multiple negative electrode plates are stacked with separators interposed between them; and a case for housing the electrode assembly; the multiple positive electrode plates and multiple negative electrode plates each have a main surface where they are stacked in the stacking direction of the multiple positive electrode plates and multiple negative electrode plates, and an end surface that intersects with the main surface; the separator includes a first region that is arranged on the end surface around the outermost periphery of the electrode assembly; and a sheet member that is arranged between the first region of the separator and the end surfaces of the multiple positive electrode plates and multiple negative electrode plates and is made of a material separate from the separator.

[2] The secondary battery described in [1], wherein the separator includes a second region that is zigzag folded along the plurality of positive electrode plates and the plurality of negative electrode plates.

[3] A secondary battery according to [1] or [2], wherein the end surfaces include a first end surface and a second end surface that face each other, and the sheet member is disposed on only one side of the first end surface or the second end surface.

[4] A secondary battery described in any one of [1] to [3], wherein the first region of the separator directly faces the inner circumferential surface of the case, with only gas, only electrolyte, or only gas and electrolyte interposed therebetween.

[5] A secondary battery according to any one of [1] to [4], further comprising a positive electrode terminal and a negative electrode terminal electrically connected to a plurality of positive electrode plates and a plurality of negative electrode plates, respectively, and the case includes a case body having a first opening and a second opening facing the first opening, a first sealing plate provided with a positive electrode terminal and sealing the first opening, and a second sealing plate provided with a negative electrode terminal and sealing the second opening.

[6] A method for manufacturing a secondary battery, comprising: a step of preparing a case body having a first opening and a second opening facing the first opening; a step of preparing a stacked electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are stacked with a separator interposed therebetween; a step of accommodating the electrode body in the case body; and a step of sealing the first opening and the second opening with a first sealing plate and a second sealing plate after accommodating the electrode body in the case body, wherein the plurality of positive electrode plates and the plurality of negative electrode plates each have a main surface where they are stacked in a stacking direction of the plurality of positive electrode plates and the plurality of negative electrode plates and an end surface intersecting the main surface, the step of preparing the electrode body includes arranging a first region of a separator on the end surface around the outermost periphery of the electrode body, and further comprising a step of arranging a sheet member made of a material separate from the separator between the first region of the separator and the end surfaces of the plurality of positive electrode plates and the plurality of negative electrode plates, and the step of accommodating the electrode body in the case body includes inserting the electrode body together with the sheet member into the case body with the sheet member positioned vertically below the electrode body.

This technology allows for efficient housing of a laminated electrode assembly, consisting of positive and negative plates, while minimizing damage to the electrode assembly by placing a sheet member made of a separate material from the separator between the first region of the separator arranged at the outermost periphery of the electrode assembly and the end faces of the positive and negative plates.

FIG. 2 is a front view of the secondary battery. 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. FIG. 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. FIG. FIG. 2 is a diagram showing an electrode assembly taken out from the electrode assembly shown in FIG. 1 . FIG. 6 is a cross-sectional view of the electrode body shown in FIG. 5 . FIG. 2 is a front view showing a negative electrode blank before being formed into a negative electrode plate. 8 is a cross-sectional view of the negative electrode plate taken along line VIII-VIII of FIG. 7. FIG. 2 is a front view showing a negative electrode plate formed from a negative electrode original plate. FIG. 2 is a front view showing a positive electrode plate before it is formed into a positive electrode plate. 11 is a cross-sectional view of the positive electrode plate shown in FIG. 10 taken along the line XI-XI. FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. FIG. 2 is a cross-sectional view of a connection structure between a negative electrode tab group and a negative electrode current collector. FIG. 2 is a cross-sectional view of a connection structure between a positive electrode tab group and a positive electrode current collector. FIG. 1 is a top view (part 1) of a sheet member according to an example. FIG. 10 is a second top view of a sheet member according to an example. 17 is a cross-sectional view of the sheet member shown in FIGS. 15 and 16 taken along line AA. FIG. FIG. 18 is a diagram showing a modified example of the AA cross section shown in FIG. 17. FIG. 10 is a top view (part 3) of a sheet member according to an example. 20 is a cross-sectional view of the sheet member shown in FIG. 19 taken along the line BB. FIG. 10 is a diagram (part 1) showing a state in which the electrode body is held by a holding member. FIG. 2 is a diagram (part 2) showing the state in which the electrode body is held by the holding member. 10A and 10B are diagrams (part 1) showing the process of inserting an electrode body held by a holding member into a case. FIG. 10 is a diagram (part 2) showing the process of inserting the electrode assembly held by the holding member into the case. FIG. 2 is a flow chart showing each step of a method for manufacturing a secondary battery.

The following describes an embodiment of the present technology. Note that the same or corresponding parts are designated by the same reference symbols, and their descriptions may not be repeated.

Note that in the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the embodiments described below, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects mentioned in the present embodiments.

In this specification, the terms "comprise," "include," and "have" are open-ended. In other words, when a certain feature is included, other features may or may not be included.

In addition, when geometric terms and terms expressing positional or directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

In this specification, "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, "electrode" may collectively refer to positive and negative electrodes. Also, "electrode plate" may collectively refer to positive and negative plates.

(Overall battery configuration)
Fig. 1 is a front view of a secondary battery 1 according to this embodiment. Figs. 2 to 4 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, and IV, respectively.

The secondary battery 1 can be installed in electric vehicles (BEVs: Battery Electric Vehicles), plug-in hybrid electric vehicles (PHEVs: Plug-in Hybrid Electric Vehicles), and hybrid electric vehicles (HEVs: Hybrid Electric Vehicles), etc. However, the use of the secondary battery 1 is not limited to vehicle use.

As shown in Figures 1 to 4, the secondary battery 1 includes an exterior body 100 and an electrode assembly 200. The exterior body 100 includes a case main body 110, a sealing plate 121 (first sealing plate), and a sealing plate 122 (second sealing plate).

In this specification, the X-axis direction (first direction) shown in Figures 1 to 4 may be referred to as the "width direction" of the secondary battery 1 or case body 110, the Y-axis direction (second direction) may be referred to as the "thickness direction" of the secondary battery 1 or case body 110, and the Z-axis direction (third direction) may be referred to as the "height direction" of the secondary battery 1 or case body 110.

When constructing a battery pack including secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y-axis direction) by a restraining member to form a battery module, or the battery pack may be supported directly on the side of the battery pack case without using a restraining member.

The case body 110 is made of a cylindrical, preferably rectangular, member. This results in a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

As shown in Figures 1 and 2, sealing plates 121, 122 are provided at both ends of the case body. The case body 110 can be formed into a rectangular tube shape, for example, by abutting the edges of bent plate-shaped members (joint 110A shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may be rounded.

In this embodiment, the case body 110 is formed so that it is longer in the width direction (X-axis direction) of the secondary battery 1 than in the thickness direction (Y-axis direction) and height direction (Z-axis direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X-axis direction is preferably approximately 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z-axis direction is preferably approximately 20 cm or less, more preferably approximately 15 cm or less, and even more preferably approximately 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, which improves mountability in a vehicle, for example.

As shown in FIG. 3 , an opening 111 (first opening) is provided at one end of the case body 110. The opening 111 is sealed by a sealing plate 121. The sealing plate 121 is provided with a negative electrode terminal 131 (first electrode terminal), a liquid inlet 141, and a gas exhaust valve 151. The positions of the negative electrode terminal 131, the liquid inlet 141, and the gas exhaust valve 151 can be changed as appropriate. The opening 111 and the sealing plate 121 have a generally rectangular shape with the Y-axis direction as the short side and the Z-axis direction as the long side.

As shown in FIG. 4, an opening 112 (second opening) is provided at one end of the case body 110. The opening 112 is sealed by a sealing plate 122. The sealing plate 122 is provided with a positive electrode terminal 132 (second electrode terminal), a liquid inlet 142, and a gas exhaust valve 152. The positions of the positive electrode terminal 132, the liquid inlet 142, and the gas exhaust valve 152 can be changed as appropriate. The opening 112 and the sealing plate 122 have a generally rectangular shape with the Y-axis direction as the short side and the Z-axis direction as the long side.

The sealing plates 121 and 122 are made of metal. Specifically, the sealing plates 121 and 122 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

The negative electrode terminal 131 is electrically connected to the negative electrode of the electrode body 200. The positive electrode terminal 132 is electrically connected to the positive electrode of the electrode body 200.

The negative electrode terminal 131 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. The outer surface of the negative electrode terminal 131 may also be provided with a portion or layer made of aluminum or an aluminum alloy.

The positive electrode terminal 132 is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy.

The liquid inlet holes 141 and 142 are sealed with a sealing member (not shown). Examples of sealing members that can be used include blind rivets and other metal members.

The gas exhaust valves 151 and 152 break when the pressure inside the exterior body 100 reaches or exceeds a predetermined value, releasing the gas inside the exterior body 100 to the outside.

(Configuration of electrode body 200)
Fig. 5 is a diagram showing the electrode body 200 housed in the exterior body 100. Fig. 6 is a cross-sectional view of the electrode body 200. The electrode body 200 is housed in the exterior body 100 so that its longitudinal direction is parallel to the X-axis direction.

The electrode assembly 200 includes a negative electrode tab group 210A (first electrode tab group) provided at the end (first end) on the sealing plate 121 side, and a positive electrode tab group 220A (second electrode tab group) provided at the end (second end) on the sealing plate 122 side. The negative electrode tab group 210A and positive electrode tab group 220A are connected to the negative electrode plate 210 and positive electrode plate 220 of the electrode assembly 200, respectively. The negative electrode tab group 210A and positive electrode tab group 220A are formed to protrude from the main body portion of the electrode assembly 200 (the portion where the positive electrode plate and negative electrode plate are stacked with a separator interposed between them) toward the sealing plates 121 and 122, respectively.

The electrode assembly 200 is housed together with an electrolytic solution (electrolyte) (not shown). The electrolytic solution (non-aqueous electrolytic solution) may be, for example, a non-aqueous solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio (25°C) of 30:30:40, with _LiPF6 dissolved at a concentration of 1.2 mol/L. A solid electrolyte may be used instead of the electrolytic solution.

As shown in Figures 5 and 6, the electrode assembly 200 includes a negative electrode plate 210, a positive electrode plate 220, and a separator 230. The negative electrode plate 210 and the positive electrode plate 220 each have a main surface (a surface extending in the vertical direction in Figure 6) and an end surface (a surface extending in the horizontal direction in Figure 6). The main surface and the end surface intersect each other approximately perpendicularly. The main surfaces of the negative electrode plate 210 and the positive electrode plate 220 are stacked in the stacking direction (Y-axis direction).

The number of negative electrode plates 210 and positive electrode plates 220 stacked is not limited to that shown in Figure 6. In one example, 30 or more negative electrode plates 210 and 30 or more positive electrode plates 220 are stacked.

The negative electrode plates 210 and positive electrode plates 220 are stacked via a separator 230. The separator 230 has a first region 231, a second region 232, and a third region 233. The first region 231 is a region located on the outermost periphery of the electrode assembly 200 on one end face (first end face) of the negative electrode plates 210 and the positive electrode plates 220 (lower side in FIG. 6). The second region 232 is a region folded zigzag along the multiple positive electrode plates 220 and the multiple negative electrode plates 210. The third region 233 is a region located on the outermost periphery of the electrode assembly 200 on the other end face (second end face) of the negative electrode plates 210 and the positive electrode plates 220 (upper side in FIG. 6).

In the cross-sectional view of Figure 6, the first region 231, second region 232, and third region 233 of the separator 230 are composed of continuous, strip-shaped insulating sheets, but the scope of the present technology is not limited to this. For example, the first region 231 and third region 233 (peripheral portions) and the second region 232 (laminated portion) may be composed of separate insulating sheets.

More specifically, for example, the second region 232 of the separator 230 may be formed from a rectangular or bag-shaped insulating sheet, and the first region 231 and third region 233 of the separator 230 may be formed by covering (wrapping) the outer periphery of the electrode assembly 200 with a strip-shaped insulating sheet. Tape, adhesive bonding, or welding of the separators 230 to each other may be used to secure the edges of the separator 230 wrapped around the outer periphery of the electrode assembly 200.

In addition, the insulating sheet may be overlapped in the first region 231 and the third region 233, i.e., the portion extending from the zigzag second region 232 may be wound multiple times around the outer periphery of the negative electrode plate 210 and the positive electrode plate 220.

In one example, the separator 230 faces the inner circumferential surface of the case body 110 without any other components in between. In this case, the separator 230 directly faces the inner circumferential surface of the case body 110 via only gas, only electrolyte, or only gas and electrolyte. However, the scope of the present technology is not limited to this, and other components, such as an insulating electrode holder, may be provided between the separator 230 and the case body 110.

As shown in Figures 5 and 6, a sheet member 500 is disposed between the first region 231 of the separator 230 and the end faces of the multiple negative electrode plates 210 and positive electrode plates 220. The sheet member 500 is formed from a separate member from the separator 230. The sheet member 500 is formed from an insulating material. In one example, the sheet member 500 is formed from a resin such as polypropylene (PP).

In the example shown in Figures 5 and 6, the sheet member 500 is arranged only on the first region 231 side (first end face side) of the separator 230's first region 231 side and third region 233 side. However, the scope of the present technology is not limited to this, and the separator 230 may be arranged on both the first region 231 and the third region 233.

The length (L2) of the sheet member 500 in the Y-axis direction is preferably at least 0.7 times the length of the negative electrode active material layer 212 in the Y-axis direction, which will be described later, and is more preferably greater than the length of the negative electrode active material layer 212 in the Y-axis direction. Even more preferably, as shown in FIG. 5, the length (L2) of the sheet member 500 in the Y-axis direction is greater than the length (L1) of the long side of the electrode body 200, i.e., the width of the strip-shaped separator 230.

As shown in FIG. 6, the width (W2) of the sheet member 500 in the X-axis direction is preferably smaller than the thickness (W1) of the electrode assembly 200 including the outermost separator 230. The width (W2) of the sheet member 500 is preferably at least 0.5 times the thickness (W1) of the electrode assembly 200, and more preferably at least 0.7 times the thickness (W1).

The thickness of the sheet member 500 is preferably greater than the thickness of the separator 230. In one example, the thickness of the sheet member 500 is preferably approximately 100 μm (0.1 mm) or more, or approximately 200 μm (0.2 mm) or more. The thickness of the sheet member 500 is, for example, approximately 500 μm (0.5 mm) or less. In one example, the sheet member 500 is made of a non-porous material or a material with a porosity of approximately less than 10%. In one example, the sheet member 500 has grooves formed therein or multiple openings (e.g., five or more) with a diameter of approximately 5 mm or more formed therein. In one example, the sheet member 500 is arranged in a direction approximately perpendicular to the negative electrode plate 210 and the positive electrode plate 220. However, the scope of the present technology is not limited to these examples.

(Configuration of electrode plate)
FIG. 7 is a front view showing a negative electrode original plate 210S before the negative electrode plate 210 (first electrode) is formed, FIG. 8 is a cross-sectional view of the negative electrode original plate 210S shown in FIG. 7 taken along line VIII-VIII, and FIG. 9 is a front view showing the negative electrode plate 210 formed from the negative electrode original plate 210S.

The negative electrode plate 210 is manufactured by processing a negative electrode base plate 210S. As shown in Figures 7 and 8, the negative electrode base plate 210S includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is copper foil or copper alloy foil.

Anode active material layers 212 are formed on both sides of the anode substrate 211, except for one end. The anode active material layers 212 are formed by applying anode active material layer slurry using a die coater.

The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders, and water as a dispersion medium in a graphite:SBR:CMC mass ratio of approximately 98:1:1.

The negative electrode substrate 211 coated with the negative electrode active material layer slurry is dried to remove the water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. The negative electrode active material layer 212 is then compressed to form the negative electrode base plate 210S, which includes the negative electrode substrate 211 and the negative electrode active material layer 212. The negative electrode base plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode base plate 210S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

As shown in Figure 9, a plurality of negative electrode tabs 210B, each made of a negative electrode core 211, are provided at one widthwise end of the negative electrode plate 210 formed from the negative electrode original plate 210S. When the negative electrode plates 210 are stacked, the plurality of negative electrode tabs 210B are stacked to form a negative electrode tab group 210A. Note that the shape of the negative electrode tabs 210B is not limited to the example shown in Figure 9.

Figure 10 is a front view showing the positive electrode plate 220S before the positive electrode plate 220 (second electrode) is formed, Figure 11 is an X-X cross-sectional view of the positive electrode plate 220S shown in Figure 10, and Figure 12 is a front view showing the positive electrode plate 220 formed from the positive electrode plate 220S.

The positive electrode plate 220 is manufactured by processing a positive electrode base plate 220S. As shown in Figures 10 and 11, the positive electrode base plate 220S includes a positive electrode core 221, a positive electrode active material layer 222, and a positive electrode protective layer 223. The positive electrode core 221 is aluminum foil or aluminum alloy foil.

A positive electrode active material layer 222 is formed on both sides of the positive electrode core 221, except for one end. The positive electrode active material layer 222 is formed on the positive electrode core 221 by applying a positive electrode active material layer slurry using a die coater.

The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as the positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium so that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

The positive electrode protective layer 223 is in contact with the positive electrode core 221 and is formed on one end of the positive electrode active material layer 222 in the width direction. The positive electrode protective layer 223 is formed on the positive electrode core 221 by applying a positive electrode protective layer slurry using a die coater. The positive electrode protective layer 223 has a higher electrical resistance than the positive electrode active material layer 222.

The positive electrode protective layer slurry is prepared by kneading alumina powder, a carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium so that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

The positive electrode substrate 221 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed, thereby forming the positive electrode active material layer 222 and the positive electrode protective layer 223. The positive electrode active material layer 222 is then compressed to form the positive electrode substrate 220S, which includes the positive electrode substrate 221, the positive electrode active material layer 222, and the positive electrode protective layer 223. The positive electrode substrate 220S is cut into a predetermined shape to form the positive electrode plate 220. The positive electrode substrate 220S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

As shown in Figure 12, a plurality of positive electrode tabs 220B made of positive electrode cores 221 are provided at one widthwise end of the positive electrode plate 220 formed from the positive electrode original plate 220S. When the positive electrode plates 220 are stacked, the plurality of positive electrode tabs 220B are stacked to form a positive electrode tab group 220A. Note that the shape of the positive electrode tabs 220B is not limited to the example shown in Figure 12.

A positive electrode protective layer 223 is provided at the base of each of the multiple positive electrode tabs 220B. It is not necessary for the positive electrode protective layer 223 to be provided at the base of the positive electrode tab 220B.

In a typical example, the thickness of the negative electrode tab 210B (one tab) is smaller than the thickness of the positive electrode tab 220B (one tab). In this case, the thickness of the negative electrode tab group 210A is smaller than the thickness of the positive electrode tab group 220A.

(Connection structure between electrode body 200 and current collector)
13 is a cross-sectional view of the connection structure between the negative electrode tab group 210A and the negative electrode current collector 310. As shown in FIG. 13 , the negative electrode tab group 210A is joined to the negative electrode current collector 310 at a joint 310A. The joint 310A can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. The joint 310A forms a conductive path between the negative electrode tab group 210A and the negative electrode terminal 131.

The negative electrode current collector 310 is connected to the negative electrode terminal 131 between the electrode assembly 200 and the sealing plate 121. The negative electrode current collector 310 includes a first conductive member 311 and a second conductive member 312. The first conductive member 311 and the second conductive member 312 are joined at a joint 313.

The negative electrode tab group 210A is joined to the first conductive member 311 of the negative electrode current collector 310 at joint 310A. The first conductive member 311 is connected to the second conductive member 312 at joint 313. Joint 313 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc.

The first conductive member 311 and the second conductive member 312 are attached to the inner surface of the sealing plate 121 via a resin insulating member 410.

The negative electrode terminal 131 is attached to the sealing plate 121 via a resin insulating member 410A. The negative electrode terminal 131 is exposed to the outside of the sealing plate 121 and is positioned so as to reach the second conductive member 312 of the negative electrode current collector 310, which is positioned on the inside of the sealing plate 121. The negative electrode terminal 131 and the second conductive member 312 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, or crimping. In this embodiment, a through hole is formed in the second conductive member 312, the negative electrode terminal 131 is inserted into the through hole, the negative electrode terminal 131 is crimped onto the second conductive member 312, and then the crimped portion is welded to the second conductive member 312 at the joint 131A, thereby connecting the negative electrode terminal 131 and the second conductive member 312.

The assembly procedure for each component is as follows: first, the negative electrode terminal 131 and second conductive member 312 are attached to the sealing plate 121 along with the insulating members 410 and 410A. Next, the first conductive member 311 connected to the electrode body 200 is attached to the second conductive member 312. At this time, the first conductive member 311 is placed on the insulating member 410 so that a portion of the first conductive member 311 overlaps the second conductive member 312. Next, the first conductive member 311 and the second conductive member 312 are welded together at the joint 313. Note that the insulating members 410 and 410A may be composed of a single member.

However, the negative electrode terminal 131 may be electrically connected to the sealing plate 121. Alternatively, the sealing plate 121 may serve as the negative electrode terminal 131.

Note that while Figure 13 illustrates an example of a negative electrode current collector 310 made up of two components (first conductive member 311 and second conductive member 312), the negative electrode current collector 310 may also be made up of a single component.

Figure 14 is a cross-sectional view of the connection structure between the positive electrode tab group 220A and the positive electrode current collector 320. As shown in Figure 14, the positive electrode current collector 320 is provided on the inner surface of the sealing plate 122 and is connected to the electrode assembly 200 and the positive electrode terminal 132. The positive electrode current collector 320 includes a first conductive member 321 (first component) and a second conductive member 322 (second component). The first conductive member 321 and the second conductive member 322 are joined at a joint 323. The first conductive member 321 and the second conductive member 322 are attached to the inner surface of the sealing plate 122 via a resin insulating member 420.

The first conductive member 321 has a stepped portion 321A. The stepped portion 321A extends in the long side direction (Z-axis direction) of the rectangular sealing plate 122. As shown in FIG. 14 , in a region (first region) on one side (left side in FIG. 14 ) of the stepped portion 321A, the first conductive member 321 is arranged along the sealing plate 122 and is joined to the positive electrode tab group 220A (joint portion 320A). In a region (second region) on the other side (right side in FIG. 14 ) of the stepped portion 321A, the first conductive member 321 is arranged to overlap the second conductive member 322.

The positive electrode tab group 220A is joined to the first conductive member 321 of the positive electrode current collector 320 at joint 320A. The first conductive member 321 is connected to the second conductive member 322 at joint 323. Joint 323 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc.

The positive electrode terminal 132 is attached to the sealing plate 122 via a resin insulating member 420A. The positive electrode terminal 132 is exposed to the outside of the sealing plate 122 and is positioned so as to reach the second conductive member 322 of the positive electrode current collector 320, which is positioned on the inside of the sealing plate 122. The positive electrode terminal 132 and the second conductive member 322 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, or crimping. In this embodiment, a through hole is formed in the second conductive member 322, the positive electrode terminal 132 is inserted into the through hole, the positive electrode terminal 132 is crimped onto the second conductive member 322, and then the crimped portion is welded to the second conductive member 322 at the joint 132A, thereby connecting the positive electrode terminal 132 and the second conductive member 322.

The assembly procedure for each component involves first attaching the positive electrode terminal 132 and second conductive member 322 to the sealing plate 122 along with the insulating members 420 and 420A. Next, the first conductive member 321 connected to the electrode body 200 is attached to the second conductive member 322. At this time, the first conductive member 321 is placed on the insulating member 420 so that a portion of the first conductive member 321 overlaps the second conductive member 322. Next, the first conductive member 321 and the second conductive member 322 are welded together at the joint 323. Note that the insulating members 420 and 420A may be constructed from a single member.

However, the positive electrode terminal 132 may be electrically connected to the sealing plate 122. Alternatively, the sealing plate 122 may serve as the positive electrode terminal 132.

Note that while Figure 14 illustrates a positive electrode current collector 320 made up of two components (first conductive member 321 and second conductive member 322), the positive electrode current collector 320 may also be made up of a single component.

In the present technology, the connection structure between the electrode assembly 200 and the current collector is not limited to the structure shown in Figures 13 and 14. For example, the positive electrode tab group 220A may be electrically connected to the sealing plate 122 directly or via the positive electrode current collector 320. In this case, the sealing plate 122 may also serve as the positive electrode terminal 132.

(Configuration of sheet member 500)
15 and 16 are top views of an example of a sheet member 500. Fig. 17 is a cross-sectional view taken along line AA of the sheet member 500 shown in Figs. 15 and 16, and Fig. 18 is a diagram showing a modified example of the cross-section AA shown in Fig. 17.

As shown in Figures 15 to 18, the sheet member 500 may have an uneven surface including protrusions 510 and grooves 520. The protrusions 510 and grooves 520 extend across the entire sheet member 500 in the insertion direction (X-axis direction) of the electrode body 200. By forming the protrusions 510 and grooves 520, frictional resistance between the electrode body 200, with the sheet member 500 interposed therebetween, and the inner surface of the case body 110 is reduced, allowing the electrode body 200 to be inserted more smoothly.

The convex portion 510 and the groove portion 520 may be formed on both the top and bottom surfaces as shown in Figure 17, or may be formed only on the bottom surface (the case body 110 side) as shown in Figure 18.

The depth of the groove 520 is preferably, for example, approximately 100 μm (0.1 mm) or more, and more preferably approximately 200 μm (0.2 mm) or more.

In the example of Figure 16, a through hole 500A is provided in the sheet member 500. By forming the through hole 500A in the sheet member 500, the flow of the electrolyte solution is promoted after the electrode body 200 is housed in the outer casing 100, and as a result, the penetration of the electrolyte solution into the electrode body 200 can be promoted.

Figure 19 is a top view of an example sheet member 500, and Figure 20 is a cross-sectional view of the sheet member 500 shown in Figure 19 taken along line B-B.

In the example shown in Figures 19 and 20, a through hole 530 is formed extending in the X-axis direction over almost the entire X-axis direction. Similar to the uneven shape described above, the through hole 530 reduces the frictional resistance between the electrode body 200 and the inner surface of the case body 110 when inserting the electrode body 200, and promotes the flow of electrolyte after inserting the electrode body 200, thereby facilitating the penetration of the electrolyte into the electrode body 200.

(Insertion of electrode body 200 into case body 110)
21 and 22 are diagrams showing a state in which the electrode assembly 200 is held by a holding member 600. As shown in Fig. 21 and 22, the electrode assembly 200 is sandwiched by the holding members 600 from both sides in the thickness direction (Y-axis direction). In Fig. 21, the negative electrode tab group 210A and the positive electrode tab group 220A are in a state in which the negative electrode plates 210 and the positive electrode plates 220 remain stacked.

From the state shown in Figure 21, as shown in Figure 22, while the electrode body 200 is held by the holding member 600, the negative electrode tab group 210A and the positive electrode tab group 220A are collected into foil.

Figures 23 and 24 show the process of inserting the electrode assembly 200 held by the holding member 600 into the case body 110.

As shown in Figures 23 and 24, after the negative electrode tab group 210A and the positive electrode tab group 220A are collected, the electrode body 200 is inserted into the case body 110 together with the holding member 600 while still being held by the holding member 600.

As shown in Figure 23, the electrode body 200 may be inserted with the longitudinal direction (X-axis direction) of the case body 110 held horizontal, or as shown in Figure 24, the electrode body 200 may be inserted with the longitudinal direction (X-axis direction) of the case body 110 tilted obliquely with respect to the horizontal (tilted by an angle θ (0° < θ < 90°) so that the insertion opening is facing upward).

In this way, by continuing to hold the electrode body 200 with the holding member 600 from the time the negative electrode tab group 210A and positive electrode tab group 220A are collected until they are inserted into the case body 110, it is possible to prevent the negative electrode plates 210 and positive electrode plates 220 from shifting in their stacking due to processing and transportation up to insertion into the case body 110.

The process of housing the electrode body 200 in the case body 110 is performed by inserting the electrode body 200 together with the holding member 600 into the case body 110 with the sheet member 500 positioned vertically below the electrode body 200, as shown in Figures 23 and 24. After the electrode body 200 has been inserted into the case body 110, the holding (chuck) of the electrode body 200 by the holding member 600 is released, and only the holding member 600 is pulled out from the case body 110, leaving the electrode body 200 in the case body 110.

This prevents the negative electrode plate 210 and the positive electrode plate 220 from shifting when stacked during the process of inserting the electrode body 200 into the case body 110, reduces the load acting on the ends of the electrode body 200, and prevents damage to the electrode body 200.

(Manufacturing process of secondary battery 1)
25 is a flow chart showing the steps of the manufacturing method of the secondary battery 1. As shown in Fig. 25, in S10, the case body 110 is prepared. Next, in S20, the electrode body 200 is fabricated, in S30, the sheet member 500 is arranged, and in S40, the electrode body 200 is inserted into the case body 110.

First, multiple negative electrode plates 210 and positive electrode plates 220 are stacked with separators 230 interposed between them (S21), and then a sheet member 500 is placed between the electrode assembly 200 and the first region 231 of the separator 230 (S30). Next, the electrode assembly 200 is held by a holding member 600 (S41). While holding the electrode assembly 200, the negative electrode tab group 210A and the positive electrode tab group 220A are each collected (S22), and then the electrode assembly 200 together with the holding member 600 is inserted into the case body 110 (S42). After the electrode assembly 200 and holding member 600 are inserted into the case body 110, only the holding member 600 is pulled out of the case body 110, leaving the electrode assembly 200 inside the case body 110 (S43).

After the electrode assembly 200 has been inserted into the case body 110 (S40), the negative electrode tab group 210A and positive electrode tab group 220A are electrically connected to the negative electrode terminal 131 and positive electrode terminal 132, respectively. This electrical connection process may be performed before inserting the electrode assembly 200 into the case body 110. Furthermore, the openings 111 and 112 are sealed with sealing plates 121 and 122, respectively (S50). The sealing process using sealing plates 121 and 122 is performed, for example, by laser welding.

The process (S51) of sealing the opening 111 with the negative electrode sealing plate 121 may be performed after the process (S52) of sealing the opening 112 with the positive electrode sealing plate 122, or at least some of the processes (S51, S52) of sealing with the sealing plates 121, 122 may be performed simultaneously. Furthermore, one of the processes (S51, S52) of sealing with the sealing plates 121, 122 may be performed before inserting the electrode assembly 200 into the case body 110 (S40).

After the sealing step (S50) using the sealing plates 121, 122 is completed, electrolyte is poured into the exterior body 100 through the liquid filling holes 141, 142, which are then sealed. After the liquid filling holes 141, 142 are sealed, the secondary battery 1 is completed after undergoing a predetermined inspection process.

(Action and effect)
According to the secondary battery 1 of this embodiment, the electrode body 200 is inserted into the case body 110 having openings 111 and 112 facing each other, and the negative terminal 131 and the positive terminal 132 are respectively provided on the sealing plates 121 and 122 that seal the openings 111 and 112, thereby reducing the height of the secondary battery 1 and improving the mountability of the secondary battery 1 in a vehicle.

Furthermore, by disposing a sheet member 500 made of a separate material from the separator 230 between the first region 231 of the separator 230 arranged at the outermost periphery of the electrode body 200 and the end faces of the negative electrode plate 210 and positive electrode plate 220, and having the sheet member 500 function as a guide when inserting the electrode body 200 into the case body 110, it is possible to suppress misalignment of the negative electrode plate 210 and positive electrode plate 220 in the laminated electrode body 200 and reduce the load acting on the end of the electrode body 200.

Furthermore, by using a strip-shaped separator 230 in which the first region 231 and third region 233 provided at the outermost periphery of the electrode assembly 200 are continuous with the second region 232 folded zigzag along the multiple negative electrode plates 210 and positive electrode plates 220, it is possible to more effectively suppress stacking misalignment of the negative electrode plates 210 and positive electrode plates 220.

Furthermore, by providing the sheet member 500 only on the first region 231 side of the separator 230's first region 231 and third region 233, it is possible to suppress stacking misalignment of the negative electrode plate 210 and the positive electrode plate 220 while suppressing a decrease in the volumetric energy density of the secondary battery 1.

Furthermore, by directly opposing the electrode body 200 to the inner surface of the case body 110 without using other components such as an insulator holder, it is possible to suppress stacking misalignment of the negative electrode plate 210 and the positive electrode plate 220 while suppressing a decrease in the volumetric energy density of the secondary battery 1.

Furthermore, by continuing to hold the electrode body 200 using the holding member 600 from the time the negative electrode tab group 210A and positive electrode tab group 220A are collected until they are inserted into the case body 110, stacking misalignment of the negative electrode plates 210 and positive electrode plates 220 can be more effectively suppressed.

As a result of the above, the secondary battery 1 and its manufacturing method according to this embodiment enable the electrode body 200 to be efficiently housed in the case body 110 while minimizing damage to the electrode body 200.

The above describes embodiments of the present technology, but the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

1 Secondary battery, 100 Exterior body, 110 Case body, 110A Joint, 111, 112 Opening, 121, 122 Sealing plate, 131 Negative electrode terminal, 131A Joint, 132 Positive electrode terminal, 132A Joint, 141, 142 Inlet hole, 151, 152 Gas release valve, 200 Electrode body, 210 Negative electrode plate, 210A Negative electrode tab group, 210B Negative electrode tab, 210S Negative electrode base plate, 211 Negative electrode core, 212 Negative electrode active material layer, 220 Positive electrode plate, 220A Positive electrode tab group, 220B Positive electrode tab, 220S Positive electrode base plate, 221 Positive electrode core, 222 Positive electrode active material layer, 223 Positive electrode protective layer, 230 Separator, 231 First region, 232, second region, 233, third region, 310, negative electrode current collector, 310A, joint portion, 311, 321, first conductive member, 312, 322, second conductive member, 313, 323, joint portion, 320, positive electrode current collector, 320A, joint portion, 321A, step portion, 410, 410A, 420, 420A, insulating member, 500, sheet member, 500A, through hole, 510, convex portion, 520, groove portion, 530, through hole, 600, holding member.

Claims (4)

preparing a case body having a first opening and a second opening opposite the first opening;
preparing a stacked electrode assembly in which a plurality of positive electrode plates and a plurality of negative electrode plates are stacked with separators interposed therebetween;
a step of housing the electrode body in the case body;
and after accommodating the electrode body in the case body, sealing the first opening and the second opening with a first sealing plate and a second sealing plate, respectively.
the plurality of positive electrode plates and the plurality of negative electrode plates each have a main surface that is stacked in a stacking direction of the plurality of positive electrode plates and the plurality of negative electrode plates, and an end surface that intersects with the main surface;
the step of preparing the electrode assembly includes disposing the first region of the separator on the end surface at the outermost periphery of the electrode assembly;
A method for manufacturing a secondary battery, further comprising a step of placing a sheet member made of a material separate from the separator between the first region of the separator and the end faces of the plurality of positive electrode plates and the plurality of negative electrode plates, wherein the step of accommodating the electrode body in the case main body includes inserting the electrode body together with the sheet member into the case main body with the sheet member positioned vertically below the electrode body. The method for manufacturing a secondary battery according to claim 1 , wherein the separator includes a second region that is zigzag folded along the plurality of positive electrode plates and the plurality of negative electrode plates. the end surfaces include a first end surface and a second end surface that face each other;
The method for manufacturing a secondary battery according to claim 1 or 2, wherein the sheet member is disposed on only one side of the first end surface and the second end surface. 3. The method for manufacturing a secondary battery according to claim 1, wherein the first region of the separator directly faces the inner circumferential surface of the case body via only gas, only electrolytic solution, or only gas and electrolytic solution.