Secondary battery and method of manufacturing the same

Abstract

To provide a secondary battery which achieves high energy density and high reliability, and to provide a method of manufacturing the secondary battery.SOLUTION: A case includes a case main body having a first opening at one end and a second opening at the other end. A step for accommodating an electrode body in the case includes inserting the electrode body into the case main body through the first opening. At an end on the positive electrode tab side of a main body portion of the electrode body, a positive electrode protective layer protrudes to the positive electrode tab side relative to an end of a negative electrode active material layer.SELECTED DRAWING: Figure 23

Description

[Technical field]

[0001] The present technology relates to a secondary battery and a manufacturing method thereof. [Background technology]

[0002] 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). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4537353 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for improving the energy density and reliability of secondary batteries. From this perspective, there is still room for improvement in the secondary battery described in Patent Document 1.

[0005] An object of the present technology is to provide a secondary battery having high energy density and high reliability, and a method for manufacturing the same. [Means for solving the problem]

[0006] The present technology provides the following secondary battery and method for manufacturing the same.

[0007] [1] A method for manufacturing an electrode body including a positive electrode plate and a negative electrode plate, and a step of housing the electrode body in a case, the case including a case body having a first opening at one end and a second opening at the other end, a first sealing plate that seals the first opening, and a second sealing plate that seals the second opening, the step of housing the electrode body in the case including inserting the electrode body into the case body from the first opening, the electrode body including a main body portion, a positive electrode tab located on the second sealing plate side of the main body portion and provided on the positive electrode plate, and a sealing plate located on the front side of the main body portion. a negative electrode tab provided on the negative electrode plate and located on the first sealing plate side, the positive electrode plate includes a positive electrode core, a positive electrode active material layer formed on the positive electrode core, and a positive electrode protection layer formed on the positive electrode core, in the positive electrode plate, the positive electrode protection layer is located on the positive electrode tab side of the positive electrode active material layer, the negative electrode plate includes a negative electrode core and a negative electrode active material layer formed on the negative electrode core, and in the main body portion of the electrode body, at an end portion on the positive electrode tab side, the positive electrode protection layer protrudes toward the positive electrode tab side beyond an end portion of the negative electrode active material layer.

[0008] [2] The method for manufacturing a secondary battery according to [1], wherein the electrode body is inserted into the case body from the end of the electrode body on which the positive electrode tab is arranged.

[0009] [3] The method for manufacturing a secondary battery according to [2], further comprising the steps of: connecting the negative electrode tab and the first sealing plate, and then inserting the electrode assembly into the case body.

[0010] [4] The method for manufacturing a secondary battery according to [2], further comprising the steps of: connecting the positive electrode tab and the second sealing plate after inserting the electrode body into the case body.

[0011] [5] The method for manufacturing a secondary battery according to any one of [1] to [4], wherein the negative electrode tab is electrically connected to the negative electrode terminal attached to the first sealing plate via a negative electrode current collector.

[0012] [6] The method for manufacturing a secondary battery according to any one of [1] to [5], wherein the positive electrode tab is electrically connected to the positive electrode terminal attached to the second sealing plate via a positive electrode current collector.

[0013] [7] The method for manufacturing a secondary battery according to any one of [1] to [6], wherein the positive electrode tab is joined to a first other member, the negative electrode tab is joined to a second other member, and a distance from a base of the positive electrode tab to a joint between the positive electrode tab and the first other member is longer than a distance from a base of the negative electrode tab to a joint between the negative electrode tab and the second other member.

[0014] [8] An electrode assembly including a positive electrode plate and a negative electrode plate, and a case that houses the electrode assembly, the case including a case body having a first opening at one end and a second opening at the other end, a first sealing plate that seals the first opening, and a second sealing plate that seals the second opening, the positive electrode plate having a positive electrode tab at an end on the second sealing plate side, the negative electrode plate having a negative electrode tab at an end on the first sealing plate side, the positive electrode plate including a positive electrode core, a positive electrode active material layer formed on the positive electrode core, and a positive electrode protective layer formed on the positive electrode core, in which, in the positive electrode plate, the positive electrode protective layer is located on the positive electrode tab side relative to the positive electrode active material layer; and the negative electrode plate includes a negative electrode core and a negative electrode active material layer formed on the negative electrode core, in which, in the electrode body, at an end portion on the positive electrode tab side, the positive electrode protective layer protrudes toward the positive electrode tab side relative to an end portion of the negative electrode active material layer.

[0015] [9] The secondary battery described in [8], wherein the positive electrode tab is joined to a first other member and the negative electrode tab is joined to a second other member, and a distance from a base of the positive electrode tab to a joint between the positive electrode tab and the first other member is longer than a distance from a base of the negative electrode tab to a joint between the negative electrode tab and the second other member.

[0016]

[10] The secondary battery according to [8] or [9], wherein the electrode assembly is a stacked electrode assembly including a plurality of the positive electrode plates and a plurality of the negative electrode plates.

[0017] When the electrode body has multiple positive electrode tabs or negative electrode tabs, the "distance from the root of the positive electrode tab to the joint between the positive electrode tab and the first other member" and the "distance from the root of the negative electrode tab to the joint between the negative electrode tab and the second other member" in [7] and [9] above refer to the distance from the "root" to the "joint" of the longest positive electrode tab or negative electrode tab among the multiple positive electrode tabs or negative electrode tabs included in the electrode body. In addition, the "distance from the root of the positive electrode tab to the joint between the positive electrode tab and the first other member" and the "distance from the root of the negative electrode tab to the joint between the negative electrode tab and the second other member" refer to the distance when the positive electrode tab or negative electrode tab is stretched without bending. Effect of the Invention

[0018] According to the present technology, it is possible to provide a secondary battery having high energy density and high reliability, and a method for manufacturing the secondary battery. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a front view showing a configuration of a secondary battery according to one embodiment. [Diagram 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Diagram 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. [Diagram 5] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. FIG. [Figure 6] 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] 1. FIG. 1 is a cross-sectional view of the secondary battery taken along the line XI-XI of FIG. [Figure 12] 2 is a cross-sectional view of the secondary battery shown in FIG. 1 taken along the line XII-XII. [Figure 13] 4 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment. [Figure 14] 1 is a perspective view showing a state before two electrode assemblies included in a secondary battery according to one embodiment are overlapped. [Figure 15] 15 is a cross-sectional view of the electrode body and the current collector shown in FIG. 14 along the line XV-XV. [Figure 16] FIG. 2 is a perspective view showing a state in which a holder and a spacer are attached to an electrode body. [Figure 17] FIG. 2 is a perspective view showing a state in which a sealing plate is attached to a negative electrode side current collector. [Figure 18] 18 is a cross-sectional view taken along the line XVIII-XVIII of the electrode body and current collector shown in FIG. 17. [Figure 19] 4 is a perspective view showing a state in which an electrode body is being inserted into a case main body. FIG. [Figure 20] FIG. 4 is a perspective view showing a state in which a sealing plate is attached to a current collector on the positive electrode side. [Figure 21] 21 is a cross-sectional view taken along the line XXI-XXI of the electrode body and current collector shown in FIG. 20. [Figure 22] FIG. 2 is a perspective view showing a configuration of a secondary battery. [Diagram 23] FIG. 2 is a schematic diagram showing the structure of an electrode body. [Figure 24] FIG. 24 is an enlarged view of a portion XXIV in FIG. [Diagram 25] 13 is a schematic diagram showing the structure of an electrode body according to a modified example. FIG. [Figure 26] FIG. 1 is a diagram (part 1) for explaining the dimensional relationship between an electrode assembly and a separator. [Figure 27] FIG. 2 is a second diagram for explaining the dimensional relationship between the electrode assembly and the separator. [Figure 28] FIG. 13 is a diagram (part 1) for explaining the dimensional relationship of the electrode tabs. [Figure 29] FIG. 2 is a second diagram for explaining the dimensional relationship of the electrode tabs. [Diagram 30] FIG. 11 is a cross-sectional view showing a configuration of a secondary battery according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof will not be repeated.

[0021] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0022] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0023] Furthermore, when geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, 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 one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0024] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0025] In the drawings, if the electrode body of the secondary battery is a laminated electrode body, the longitudinal direction of the laminated surface is the X direction, and if the electrode body is a wound electrode body, the direction along the winding axis is the X direction. Also, the short side direction of the electrode body as viewed from the X direction is the Y direction, and the longitudinal direction of the electrode body as viewed from the X direction is the Z direction. To facilitate understanding of the invention, the dimensions of each component in the drawings are sometimes shown differently from the actual dimensions.

[0026] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or the case body, the second direction (Z direction) may be referred to as the "height direction" of the secondary battery or the case body, and the third direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or the case body.

[0027] (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to one embodiment. Figs. 2 to 5 are views showing the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Fig. 6 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0028] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted on a vehicle.

[0029] 1 to 6, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case body 110, a sealing plate 120, and another sealing plate .

[0030] When configuring an assembled battery including the 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 direction) by a restraining member to form a battery module, or the assembled battery may be directly supported on the side surface of a battery pack case without using a restraining member.

[0031] 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.

[0032] As shown in Fig. 1 and Fig. 2, a sealing plate 120 (first wall) and a sealing plate 130 (second wall) 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 ends of bent plate-like members (joints 115 exemplified in Fig. 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may have an R shape. In addition, the secondary battery in the present technology is not necessarily limited to a rectangular secondary battery.

[0033] In this embodiment, the case body 110 is formed to be longer in the width direction (X direction) of the secondary battery 1 than in the thickness direction (Y direction) and height direction (Z direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X direction is preferably about 30 cm or more. This allows a relatively large (high capacity) secondary battery 1 to be configured. The dimension (height) of the case body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows a relatively low height (low height) secondary battery 1 to be configured, improving the mountability in a vehicle, for example.

[0034] The case body 110 includes a pair of first side surface portions 111 and a pair of second side surface portions 112. The pair of first side surface portions 111 constitute a part of the side surface of the case 100. The pair of second side surface portions 112 constitute the bottom surface portion and the top surface portion of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are provided so as to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. It is desirable that each of the pair of first side surface portions 111 has an area larger than each of the pair of second side surface portions 112.

[0035] 5, a gas release valve 150 is provided on one second side surface portion 112A of the pair of second side surface portions 112. The gas release valve 150 extends in the width direction (X direction) of the secondary battery 1. The gas release valve 150 extends in the X direction from the center of the case body 110 in the X direction but does not reach both ends. The gas release valve 150 can be modified as appropriate.

[0036] The thickness of the plate-like member in gas exhaust valve 150 is thinner than the thickness of the plate-like members of case body 110 other than gas exhaust valve 150. As a result, when the pressure inside case 100 reaches or exceeds a predetermined value, gas exhaust valve 150 breaks preferentially compared to other parts of case body 110, and exhausts gas inside case 100 to the outside.

[0037] 2, a joint 115 is formed on the other second side surface portion 112B of the pair of second side surface portions 112. The joint 115 extends in the width direction (X direction) of the secondary battery 1. At the joint 115, the ends of the plate-like members constituting the case body 110 are joined together.

[0038] 3, an opening 113 (first opening) is provided at an end of a first side in a first direction (X direction) of the case body 110. The opening 113 is sealed by a sealing plate 120. A joint 115 is formed in the opening 113 to seal the opening 113. The opening 113 and the sealing plate 120 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction. Note that the substantially rectangular shape includes a rectangular shape or a substantially rectangular shape with rounded corners of the rectangular shape.

[0039] A negative electrode terminal 301 is provided on the sealing plate 120 (first sealing plate). The position of the negative electrode terminal 301 can be changed as appropriate.

[0040] 4, an opening 114 (second opening) is provided at an end of a second side opposite to the first side in the first direction (X direction) of the case body 110. That is, the opening 114 is located at an end opposite to the opening 113, and the openings 113 and 114 face each other. The opening 114 is sealed by a sealing plate 130. A joint 115 is formed in the opening 114 to seal the opening 114. The opening 114 and the sealing plate 130 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0041] A positive electrode terminal 302 and a liquid injection hole 134 are provided on the sealing plate 130 (second sealing plate). The positions of the positive electrode terminal 302 and the liquid injection hole 134 can be changed as appropriate.

[0042] The sealing plate 120 and the sealing plate 130 are made of metal. Specifically, the sealing plate 120 and the sealing plate 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0043] The negative electrode terminal 301 (first electrode terminal) is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is attached to the sealing plate 120, that is, the case 100.

[0044] The positive electrode terminal 302 (second electrode terminal) is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is attached to the sealing plate 130, that is, the case 100.

[0045] The negative terminal 301 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0046] The positive terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0047] The liquid inlet 134 is sealed by a sealing member (not shown). As the sealing member, for example, a blind rivet or other metal members can be used.

[0048] The electrode body 200 is a flat-shaped electrode body in which positive and negative electrode plates, which will be described later, are stacked. Specifically, the electrode body 200 is a stacked electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked with a separator 800, which will be described later. However, in this specification, the "electrode body" is not limited to a stacked electrode body, and may be a wound electrode body in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are both wound with a strip-shaped separator. The separator can be made of, for example, a polyolefin microporous film. When the electrode body is a stacked electrode body including a plurality of positive electrode plates and a plurality of negative electrode plates, the positive electrode tabs provided on each positive electrode plate can be stacked to form a positive electrode tab group, and the negative electrode tabs provided on each negative electrode plate can be stacked to form a negative electrode tab group. The electrode body 200 may include a plurality of stacked electrode bodies, or may include a plurality of wound electrode bodies.

[0049] As shown in Fig. 6, case 100 houses electrode body 200. Fig. 6 illustrates a first electrode body 201, which will be described later. First electrode body 201 is housed in case 100 so that its longitudinal direction or winding axis is parallel to the X direction.

[0050] Specifically, one or more laminated electrode bodies or wound electrode bodies are accommodated together with an electrolytic solution (electrolyte) (not shown) inside an insulating sheet 700 (described later) arranged in the case 100. The electrolytic solution (non-aqueous electrolytic solution) is, for example, a non-aqueous solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed in a volume ratio (25° C.) of 30:30:40, and LiPF 6 A solution having a concentration of 1.2 mol / L can be used. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0051] The first electrode body 201 includes a substantially rectangular main body portion, a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group).

[0052] The main body is composed of a negative electrode plate 210 and a positive electrode plate 240, which will be described later. The negative electrode tab group 220 is located at an end of a first side of the first electrode body 201 in a first direction (X direction) with respect to the main body. The first side in this embodiment is the sealing plate 120 side. The positive electrode tab group 250 is located at an end of a second side of the first electrode body 201 in the first direction (X direction) with respect to the main body. The second side in this embodiment is the sealing plate 130 side.

[0053] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the central portion of the electrode body 200 towards the sealing plate 120 or the sealing plate 130, respectively.

[0054] The current collector 400 includes a negative electrode current collector 400A and a positive electrode current collector 400B. The negative electrode current collector 400A and the positive electrode current collector 400B are each made of a plate-shaped member. The electrode assembly 200 is electrically connected to a negative electrode terminal 301 and a positive electrode terminal 302 via the current collector 400.

[0055] The negative electrode current collector 400A is disposed on the sealing plate 120 via a resin insulating member. The negative electrode current collector 400A is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 400A is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. Details of the negative electrode current collector 400A will be described later.

[0056] The positive electrode current collector 400B is disposed on the sealing plate 130 via a resin insulating member. The positive electrode current collector 400B is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. The positive electrode current collector 400B is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy. The positive electrode tab group 250 may be electrically connected to the sealing plate 130 directly or via the positive electrode current collector 400B. In this case, the sealing plate 130 may play the role of the positive electrode terminal 302. The positive electrode current collector 400B will be described in detail later.

[0057] (Configuration of electrode body 200) 7 is a cross-sectional view of the negative electrode plate 210 (a cross-sectional view taken along line VII-VII in FIG. 8), and FIG. 8 is a front view showing the negative electrode plate 210. As shown in FIG.

[0058] 8, a plurality of negative electrode tabs 230 (first electrode tabs) made of a negative electrode core 211 are provided at one end in the width direction of the negative electrode plate 210. When the negative electrode plates 210 are stacked, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. The length in the protruding direction of each of the negative electrode tabs 230 in the plurality of negative electrode plates 210 is appropriately adjusted taking into consideration the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 400A. The shape of the negative electrode tab 230 is not limited to that exemplified in FIG.

[0059] FIG. 9 is a cross-sectional view of the positive electrode plate 240 (cross-sectional view taken along line IX-IX in FIG. 10), and FIG.

[0060] As shown in Fig. 10, a plurality of positive electrode tabs 260 (second electrode tabs) made of a positive electrode core 241 are provided at one end in the width direction of the molded positive electrode plate 240. When the positive electrode plates 240 are stacked, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. The length of each of the positive electrode tabs 260 in the protruding direction of the plurality of positive electrode plates 240 is appropriately adjusted taking into consideration the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 400B. The shape of the positive electrode tab 260 is not limited to the one exemplified in Fig. 10.

[0061] A positive electrode protective layer 243 is provided at the base of the positive electrode tab 260. The positive electrode protective layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0062] In a typical example, the thickness of the negative electrode tab 230 (one piece) is smaller than the thickness of the positive electrode tab 260 (one piece). In this case, the thickness of the negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0063] (Connection structure between electrode body 200 and current collector 400) Fig. 11 is a cross-sectional view of the secondary battery shown in Fig. 1 taken along line XI-XI. As shown in Fig. 11, the electrode body 200 includes a first electrode body 201 and a second electrode body 202. Each of the first electrode body 201 and the second electrode body 202 includes a positive electrode (second electrode) and a negative electrode (first electrode). The electrode body 200 may be composed of three or more electrode bodies.

[0064] The electrode body 200 is formed by stacking a first electrode body 201 and a second electrode body 202. The first electrode body 201 and the second electrode body 202 are aligned in the thickness direction (Y direction) of the first electrode body 201 and the second electrode body 202.

[0065] The first electrode body 201 includes a negative electrode tab group 220. The negative electrode tab group 220 is electrically connected to a current collector 410 (negative electrode current collector) at a first end 205 in the X direction. The second electrode body 202 includes a negative electrode tab group 270. The negative electrode tab group 270 is electrically connected to a current collector 430 (negative electrode current collector) at a third end 207 in the X direction.

[0066] The negative electrode tab group 220 has a curved portion 221 and a tip portion 222. The curved portion 221 is a portion where the negative electrode tab group 220 is curved on the side where the first electrode is connected, relative to the tip portion 222. The tip portion 222 is a portion located at the end of the negative electrode tab group 220 on the opposite side to the side where the first electrode is connected.

[0067] The negative electrode tab group 270 has a curved portion 271 and a tip portion 272. The curved portion 271 is a portion where the negative electrode tab group 270 is curved on the side where the first electrode is connected, relative to the tip portion 272. The tip portion 272 is a portion located at the end of the negative electrode tab group 270 on the opposite side to the side where the first electrode is connected.

[0068] The negative electrode tab group 220 and the negative electrode tab group 270 are curved in opposite directions so that the tip portions 222, 272 approach each other. In the present embodiment, the tip portions 222, 272 are spaced apart from each other, but this configuration is not limited thereto, and the tip portions 222, 272 may be in contact with each other.

[0069] The negative electrode current collector 400A electrically connects the negative electrode terminal 301 to the negative electrode tab group 220 and the negative electrode tab group 270. The negative electrode current collector 400A in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the sealing plate 120.

[0070] Negative electrode current collector 400A includes current collector 410, current collector 430 (third current collecting member), and current collector 440 (fourth current collecting member).

[0071] Current collector 410 is a plate-like member. Current collector 410 has a longitudinal direction in the Z direction and a transverse direction in the Y direction. Current collector 430 is a plate-like member. Current collector 430 has a longitudinal direction in the Z direction and a transverse direction in the Y direction. Current collector 410 and current collector 430 are arranged in parallel in the X direction. In this way, current collector 410 and current collector 430 are formed by separate parts.

[0072] The negative electrode tab group 220 is joined to the current collector 410 at a joining point 411, which will be described later. The negative electrode tab group 270 is joined to the current collector 430 at a joining point 431, which will be described later. The joining points 411, 431 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, the negative electrode tab group 220 and the current collector 410, and the negative electrode tab group 270 and the current collector 430 are joined by, for example, ultrasonic welding.

[0073] Current collector 440 is joined to current collector 410 and current collector 430 at joints (not shown) located at ends in the Z direction. Current collector 440 is connected to negative electrode terminal 301. The connection between current collector 440 and negative electrode terminal 301 can be formed by, for example, crimping and / or welding.

[0074] Negative electrode terminal 301 is provided so as to be exposed to the outside of sealing plate 120 and to reach current collector 440 of negative electrode current collector 400A provided on the inner surface side of sealing plate 120. Negative electrode terminal 301 is connected to plate-shaped member 303.

[0075] The plate-shaped member 303 is located outside the sealing plate 120. The plate-shaped member 303 is arranged so as to follow the sealing plate 120. The plate-shaped member 303 is conductive. The plate-shaped member 303 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to another adjacent secondary battery. The connection between the negative electrode terminal 301 and the plate-shaped member 303 can be formed by, for example, laser welding.

[0076] An insulating member 510 is disposed between the plate-shaped member 303 and the sealing plate 120. An insulating member 520 is disposed between the negative electrode terminal 301 and the sealing plate 120. An insulating member 530 is disposed between the current collector 440 and the sealing plate 120.

[0077] However, the negative electrode terminal 301 may be electrically connected to the sealing plate 120. Also, the sealing plate 120 may serve as the negative electrode terminal 301.

[0078] A spacer 600 is disposed between the sealing plate 120 and a main body of the electrode body 200 (not including the negative electrode tab group 220). The spacer 600 is made of an insulating resin member. The spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 engage with each other at engagement portions (not shown) at both ends in the Z direction.

[0079] The first component 610 and the second component 620 protrude in the Y direction at the end side on the electrode body 200 side in the X direction. In this way, the spacer 600 plays the role of a guide so that the bending portions 221, 271 can be easily bent when the bending portions 221, 271 are bent.

[0080] A resin insulating sheet 700 (electrode body holder) is disposed between the electrode body 200 and the case body 110. The insulating sheet 700 may be made of, for example, resin. More specifically, the material of the insulating sheet 700 is, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0081] Fig. 12 is a cross-sectional view taken along the line XII-XII of the secondary battery shown in Fig. 1. The connection structure between electrode body 200 and current collector 400 on the positive electrode side of secondary battery 1 in this embodiment differs from the structure on the negative electrode side in that portions corresponding to current collector 410 and current collector 430 on the negative electrode side are formed of a single part.

[0082] The first electrode body 201 includes a positive electrode tab group 250. The positive electrode tab group 250 is electrically connected to a current collector 420 (positive electrode current collector) at a second end 206 in the X direction. The second electrode body 202 includes a positive electrode tab group 280. The positive electrode tab group 280 is electrically connected to a current collector 420 (positive electrode current collector) at a fourth end 208 in the X direction.

[0083] The positive electrode tab group 250 has a curved portion 251 and a tip portion 252. The curved portion 251 is a portion where the positive electrode tab group 250 is curved on the side where the second electrode is connected, relative to the tip portion 252. The tip portion 252 is a portion located at the end of the positive electrode tab group 250 opposite the side where the second electrode is connected.

[0084] The positive electrode tab group 280 has a curved portion 281 and a tip portion 282. The curved portion 281 is a portion where the positive electrode tab group 280 is curved on the side where the second electrode is connected, relative to the tip portion 282. The tip portion 282 is a portion located at the end of the positive electrode tab group 280 on the opposite side to the side where the second electrode is connected.

[0085] The positive electrode tab group 250 and the positive electrode tab group 280 are curved in opposite directions so that the tip portions 252, 282 approach each other. In the present embodiment, the tip portions 252, 272 are spaced apart from each other, but this configuration is not limited thereto, and the tip portions 252, 282 may be in contact with each other.

[0086] The positive electrode current collector 400B electrically connects the positive electrode terminal 302 to the positive electrode tab group 250 and the positive electrode tab group 280. The positive electrode current collector 400B in this embodiment is connected to the positive electrode terminal 302 between the electrode body 200 and the sealing plate 130.

[0087] Positive electrode current collector 400B includes a current collector 420 (first current collecting member) and a current collector 450 (second current collecting member).

[0088] Current collector 420 is a plate-like member. Current collector 420 has a longitudinal direction in the Z direction and a lateral direction in the Y direction. Current collector 420 is configured as a single, integral part.

[0089] Positive electrode tab group 250 and positive electrode tab group 280 are joined to current collector 420, which is configured from one part, at joint 421, which will be described later. Joint 421 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, positive electrode tab group 250 and positive electrode tab group 280 are joined to current collector 420 by, for example, ultrasonic bonding.

[0090] The current collector 450 is joined to the current collector 420 at a joint (not shown) located at an end in the Z direction. The current collector 450 is connected to the positive electrode terminal 302. The connection between the current collector 450 and the positive electrode terminal 302 can be formed by, for example, crimping and / or welding.

[0091] The positive electrode terminal 302 is exposed to the outside of the sealing plate 130 and is provided so as to reach a current collector 450 of a positive electrode current collector 400B provided on the inner surface side of the sealing plate 130. The positive electrode terminal 302 is connected to a plate-shaped member 304.

[0092] The plate-shaped member 304 is located outside the sealing plate 130. The plate-shaped member 304 is arranged so as to follow the sealing plate 130. The plate-shaped member 304 is conductive. The plate-shaped member 304 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to another adjacent secondary battery. The connection between the positive electrode terminal 302 and the plate-shaped member 304 can be formed by, for example, laser welding.

[0093] An insulating member 510 is disposed between the plate-shaped member 304 and the sealing plate 130. An insulating member 520 is disposed between the positive electrode terminal 302 and the sealing plate 130. An insulating member 530 is disposed between the current collector 450 and the sealing plate 130.

[0094] However, the positive electrode terminal 302 may be electrically connected to the sealing plate 130. Also, the sealing plate 130 may serve as the positive electrode terminal 302.

[0095] A spacer 600 is disposed between the sealing plate 130 and the main body of the electrode body 200 (not including the positive electrode tab groups 250, 280). The spacer 600 is made of an insulating resin material. The spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 engage with each other at engagement portions (not shown) at both ends in the Z direction.

[0096] The first component 610 and the second component 620 protrude in the Y direction at the end side on the electrode body 200 side in the X direction. Thus, the spacer 600 plays the role of a guide so that the bending portions 251, 281 can be easily bent when the bending portions 251, 281 are bent.

[0097] Between the electrode body 200 and the case body 110, a resin insulating sheet 700 (electrode body holder) is disposed.

[0098] (Manufacturing process of secondary battery 1) Hereinafter, a method for manufacturing a secondary battery according to the present embodiment will be described. Fig. 13 is a flowchart showing a method for manufacturing a secondary battery according to the present embodiment. Fig. 14 is a perspective view showing a state before two electrode bodies included in the secondary battery according to the present embodiment are overlapped. Fig. 15 is a cross-sectional view taken along the line XV-XV of the electrode body and the current collector shown in Fig. 14.

[0099] 13, in the method for manufacturing a secondary battery according to the present embodiment, first, a first electrode body 201 and a second electrode body 202 are produced (step S1). A part of the tip of each of the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 is cut off so that the tips have the same length when bundled.

[0100] 13 to 15, after the first electrode body 201 and the second electrode body 202 are produced, the negative electrode tab group 220 is joined to the current collector 410 (S2 step). The negative electrode tab group 220 is joined to the current collector 410 at a joining portion 411. Next, the negative electrode tab group 270 is joined to the current collector 430 (S3 step). The negative electrode tab group 270 is joined to the current collector 430 at a joining portion 431.

[0101] Next, the first electrode body 201, the current collector 420, and the second electrode body 202 are arranged in this order in the first direction (DR1 direction). The positive electrode tab group 250 is arranged on one side of the current collector 420 in the first direction (DR1 direction). With the positive electrode tab group 280 arranged on the other side of the current collector 420 in the first direction (DR1 direction), the positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 (step S4). The positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 at joints 421.

[0102] In the height direction of the first electrode body 201 and the second electrode body 202, the current collector 410, the current collector 420, and the current collector 430 are arranged biased to one side from the center of the first electrode body 201 and the second electrode body 202. This allows the current collectors to be configured to be short, and therefore the current collectors can be made compact.

[0103] The current collector 410, the current collector 420, and the current collector 430 are not limited to this configuration. The current collector 410, the current collector 420, and the current collector 430 may be disposed at the center of the first electrode body 201 and the second electrode body 202 in the height direction of the first electrode body 201 and the second electrode body 202. In this case, the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 are disposed at the center of the first electrode body 201 and the second electrode body 202 in accordance with the current collector 410, the current collector 420, and the current collector 430 in the height direction of the first electrode body 201 and the second electrode body 202.

[0104] Furthermore, the order of the steps of joining the current collector 410, the current collector 420, and the current collector 430 to the first electrode body 201 and the second electrode body 202 is not limited to the above, and the order may be changed. The steps of joining the current collector 410 and the current collector 430 to the first electrode body 201 and the second electrode body 202 are preferably performed before the step of overlapping the first electrode body 201 and the second electrode body 202 described below, and preferably before the step of joining the current collector 420 to the first electrode body 201 and the second electrode body 202.

[0105] Next, after the positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420, the positive electrode tab group 250 and the positive electrode tab group 280 are folded in the thickness direction of the first electrode body 201 and the second electrode body 202 (the direction perpendicular to the DR1 direction in Figs. 14 and 15) to overlap the first electrode body 201 and the second electrode body 202 (step S5). In other words, the first electrode body 201 and the second electrode body 202 are put together.

[0106] "Overlapping the first electrode body and the second electrode body" means that the first electrode body and the second electrode body may be directly overlapped, or another member may be disposed between the first electrode body and the second electrode body. The first electrode body and the second electrode body may be fixed with tape or the like, or may not be fixed. Furthermore, the first electrode body, the current collector, and the second electrode body may not be disposed on a straight line in the first direction (DR1 direction), and the first electrode body or the second electrode body may be inclined with respect to the first direction (DR1 direction) with respect to the current collector.

[0107] The positive electrode tab group 250 and the positive electrode tab group 280 are bent so that their leading ends face each other. The negative electrode tab group 220 and the negative electrode tab group 270 are also bent so that their leading ends face each other.

[0108] 13 and 16 are perspective views showing a state in which the holder and the spacer are attached to the electrode assembly 200. As shown in Fig. 16, next, the spacer 600 and the insulating sheet 700 are assembled to the electrode assembly 200 (step S6).

[0109] The insulating sheet 700 does not necessarily have to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers an area of ​​about 50% or more, and more preferably about 70% or more, of the outer surface of the electrode body. Of the six faces of the substantially rectangular parallelepiped (flat) electrode body 200, the insulating sheet 700 preferably covers the entire four faces other than the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0110] 17 is a perspective view showing a state in which a sealing plate 120 is attached to the negative electrode side current collector. FIG 18 is a cross-sectional view taken along line XVIII-XVIII of the electrode assembly and current collector shown in FIG 17.

[0111] 13, 17, and 18, the negative electrode tab group 220 is joined to the current collector 410, the negative electrode tab group 270 is joined to the current collector 430, and the first electrode body 201 and the second electrode body 202 are overlapped, and then the current collector 410 and the current collector 430 are electrically connected to the negative electrode terminal 301 via the current collector 440 (step S7). Note that step S7 can also be performed before step S6.

[0112] Specifically, the negative electrode tab group 220 and the negative electrode tab group 270 are bent so that the tip portions 222, 272 face each other.

[0113] Negative electrode terminal 301 and current collector 440 are attached to sealing plate 120 via an insulating member. Current collector 440 is brought into contact with current collector 410 and current collector 430 in the X direction. Note that connection of plate-shaped member 303 to negative electrode terminal 301 may be made at any time. Current collector 440, current collector 410, and current collector 430 are joined by laser welding between sealing plate 120 and insulating sheet 700.

[0114] Fig. 19 is a perspective view showing a state in which the electrode bodies are being inserted into the case body. Next, as shown in Fig. 13 and Fig. 19, after the first electrode body 201 and the second electrode body 202 are overlapped, the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 from the opening 113, starting with the current collector 420 side (step S8).

[0115] The negative electrode tab group 220 and the negative electrode tab group 270 are curved by bringing the sealing plate 120 and the main body of the electrode body 200 (the first electrode body 201 and the second electrode body 202) closer to each other. It is preferable to bring the sealing plate 120 and the main body of the electrode body 200 arranged in the case body 110 closer to each other. As shown in FIG. 11 , the negative electrode tab group 220 and the negative electrode tab group 270 are curved along the shape of the spacer 600 so that the folded back portions of the curved portions 221, 271 approach the case body 110 in the Y direction.

[0116] After the sealing plate 120 is brought into contact with the case body 110, the sealing plate 120 is temporarily joined to the case body 110. By the temporary joining, the sealing plate 120 is partially joined to the opening 113 of the case body 110. As a result, the sealing plate 120 is positioned relative to the case body 110.

[0117] When the electrode body 200 is inserted into the case body 110, the electrode body 200 may be pulled from the current collector 420 side, or may be pushed from the current collector 410 and current collector 430 sides. When the electrode body 200 is pushed from the current collector 410 and current collector 430 sides, the negative electrode tab group 220 and the negative electrode tab group 270 can be bent at the same time.

[0118] Fig. 20 is a perspective view showing a state in which a sealing plate 130 is attached to the positive electrode side current collector. Fig. 21 is a cross-sectional view taken along line XXI-XXI of the electrode assembly and current collector shown in Fig. 20. Note that in Fig. 21, the case body 110 is omitted.

[0119] As shown in FIGS. 13, 20 and 21, after the first electrode body 201 and the second electrode body 202 are inserted into the case body 110, the current collector 420 is electrically connected to the positive electrode terminal 302 (step S9).

[0120] Specifically, the positive electrode terminal 302 and the current collector 450 are attached to the sealing plate 130 via an insulating member. After the first electrode body 201 and the second electrode body 202 are inserted into the case body 110, the current collector 450 is brought into contact with the current collector 420 protruding from the opening 114 in the X direction. Note that the connection of the plate-shaped member 304 to the positive electrode terminal 302 may be made at any time.

[0121] As shown in Fig. 21, the positive electrode tab group 250 and the positive electrode tab group 280 connected to the current collector 420 are bent so that the tip portions 252, 282 face each other. From the state shown in Fig. 21, the sealing plate 130 is brought into contact with the case body 110. At this time, the sealing plate 130 and the body portion of the electrode body 200 are brought close to each other, thereby bending the positive electrode tab group 250 and the positive electrode tab group 280. As shown in Fig. 12, the positive electrode tab group 250 and the positive electrode tab group 280 are bent along the shape of the spacer 600 so that the folded-back portions of the curved portions 251, 281 approach the case body 110 in the Y direction.

[0122] After the sealing plate 130 is brought into contact with the case body 110, the sealing plate 130 is temporarily welded to the case body 110. By the temporary joining, the sealing plate 130 is partially joined to the opening 114 of the case body 110. As a result, the sealing plate 130 is positioned relative to the case body 110.

[0123] Fig. 22 is a perspective view showing the configuration of the secondary battery 1. As shown in Fig. 13 and Fig. 22, next, the sealing plate 120 and the sealing plate 130 are joined to the case body 110 (step S10). The sealing plate 120 seals the opening 113 of the case body 110, and the sealing plate 130 seals the opening 114 of the case body 110. As a result, the first electrode body 201 and the second electrode body 202 are housed in the case 100.

[0124] After the above-mentioned steps, inspections such as a leak inspection are performed (step S11). After the leak inspection, the secondary battery 1 is dried to remove moisture from inside the case 100. Then, electrolyte is injected into the case 100 through the injection hole 134. When injecting the electrolyte, the case 100 is tilted with the sealing plate 130 facing up and the sealing plate 120 facing down, and the electrolyte is injected into the case 100 through the injection hole 134 of the sealing plate 130. Then, degassing charging is performed. During degassing charging, the injection hole 134 may be temporarily sealed. Then, the injection hole 134 is sealed, and the secondary battery 1 is completed.

[0125] The order of the electrode body 200 insertion step and the current collector connection step is not limited to the above example. For example, after only a part of the electrode body 200 is inserted into the case body 110 (first step) so that the end of the negative electrode active material layer 212 (second electrode active material layer) on the opening 113 side is arranged outside the case body 110, the negative electrode terminal 301 (first electrode terminal) provided on the sealing plate 120 (first sealing plate) and the negative electrode tab group 220, 270 (first electrode tab) may be electrically connected, and then the electrode body 200 may be inserted into the case body 110 until the end of the negative electrode active material layer 212 on the opening 113 side is arranged inside the case body 110 (second step). That is, the negative electrode terminal 301 and the electrode body 200 may be electrically connected during the insertion step of the electrode body 200 into the case body 110.

[0126] In this embodiment, the first electrode body 201 is provided with a negative electrode tab group 220 and a positive electrode tab group 250, and the second electrode body 202 is provided with a negative electrode tab group 270 and a positive electrode tab group 280, so that the first electrode body 201 and the second electrode body 202 have separate electrode tabs. With this configuration, the electrode tabs can be shortened compared to when the first electrode body 201 and the second electrode body 202 form a single electrode tab and bend the electrode tab. As a result, the volume occupied by the electrode tabs can be reduced, so that the energy density of the secondary battery 1 can be improved. In addition, the configuration in which separate electrode tabs are provided in the first electrode body 201 and the second electrode body 202 makes it easier to bend the electrode tabs compared to when the first electrode body 201 and the second electrode body 202 form a single electrode tab, so that the electrode tabs and the current collector can be easily joined, and the secondary battery can be stably manufactured. In particular, the secondary battery 1 can be stably manufactured, so that the reliability of the connection between the electrode tabs and the current collector can be increased.

[0127] (Structure of the End of the Electrode Body 200) FIG. 23 is a schematic diagram showing the structure of the electrode body 200, and FIG. 24 is an enlarged view of a portion XXIV in FIG.

[0128] 23 and 24, in the main body of the electrode body 200, at the end on the positive electrode tab group 250, 280 side, the positive electrode protection layer 243 protrudes toward the positive electrode tab group 250, 280 side beyond the end of the negative electrode active material layer 212. The positive electrode protection layer 243 protrudes toward the positive electrode tab group 250, 280 side (+X side) beyond the end of the negative electrode active material layer 212 by a distance G1.

[0129] Here, the positive electrode protection layer 243 protrudes beyond the end of the negative electrode active material layer 212 in the X direction (first direction) connecting the opening 113 and the opening 114. The positive electrode protection layer 243 protrudes beyond the end of the negative electrode active material layer 212 in the insertion direction of the electrode body 200. The positive electrode protection layer 243 protrudes beyond the end of the negative electrode active material layer 212 in a direction perpendicular to the sealing plates 120, 130.

[0130] The protrusion amount (G1) of the positive electrode protective layer 243 is preferably, for example, about 0.1 mm or more, more preferably about 0.5 mm or more, and even more preferably about 1.0 mm or more. The protrusion amount (G1) is, for example, preferably about 5.0 mm or less, more preferably about 3.0 mm or less, and even more preferably about 2.0 mm or less.

[0131] Furthermore, in the main body of the electrode body 200, at both ends in the Z direction, the negative electrode active material layer 212 protrudes beyond the positive electrode active material layer 242 and the positive electrode protective layer 243 by a distance G2.

[0132] Here, the negative electrode active material layer 212 protrudes further than the positive electrode active material layer 242 and the positive electrode protective layer 243 in the Z direction (second direction) perpendicular to the insertion direction (X direction) of the electrode body 200. The negative electrode active material layer 212 protrudes further than the positive electrode active material layer 242 and the positive electrode protective layer 243 in the Z direction perpendicular to the thickness direction (Y direction) of the electrode body 200. The negative electrode active material layer 212 protrudes further than the positive electrode active material layer 242 and the positive electrode protective layer 243 in a direction perpendicular to a pair of second side surface portions 112 (short side surfaces) of the case body 110.

[0133] The protrusion amount (G2) of the negative electrode active material layer 212 is preferably, for example, about 0.1 mm or more, more preferably about 3.0 mm or more, and even more preferably about 1.0 mm or more. The protrusion amount (G2) is, for example, preferably about 5.0 mm or less, more preferably about 3.0 mm or less, and even more preferably about 2.0 mm or less.

[0134] The ratio (G1 / G2) of the protrusion amount (G1) of the positive electrode protective layer 243 to the protrusion amount (G2) of the negative electrode active material layer 212 is preferably, for example, about 0.3 or more, more preferably about 1.0 or more (or greater than 1.0), and even more preferably about 1.5 or more. This makes it possible to more effectively suppress damage to the corners of the negative electrode active material layer 212. The ratio (G1 / G2) is, for example, preferably about 5.0 or less, more preferably about 3.0 or less, and even more preferably about 2.0 or less.

[0135] In the secondary battery 1 according to the present embodiment, even if a load such as a load that causes the electrode body 200 to move in the case body 110 due to vibration is applied to the vicinity of the end of the negative electrode active material layer 212 located in the +X direction when the electrode body 200 is inserted into the case body 110, damage to the end of the negative electrode active material layer 212 can be suppressed. Since burrs are easily formed on the end of the negative electrode active material layer 212, damage (falling off of the negative electrode active material) may occur during insertion into the case body 110. Here, since the positive electrode protective layer 243 protrudes toward the positive electrode tab group 250, 280 side from the end of the negative electrode active material layer 212, damage to the end of the negative electrode active material layer 212 during insertion into the case body 110 can be suppressed. As a result, a highly reliable secondary battery 1 can be obtained.

[0136] As described above, the electrode body 200 may be a wound type electrode body. However, in the stacked type electrode body exemplified in this embodiment, the problem of the negative electrode active material falling off when the electrode body 200 is inserted into the case body 110 is likely to occur. Therefore, in the case of a stacked type electrode body, by adopting the structure shown in Figures 23 and 24, it is possible to obtain a greater effect in suppressing damage to the end of the negative electrode active material layer 212.

[0137] (Positive and negative plates) Hereinafter, examples of suitable configurations of the positive and negative plates in the secondary battery 1 according to the present embodiment will be described, but the scope of the present technology is not limited thereto.

[0138] In the positive electrode plate, the positive electrode core 241 is made of a metal foil containing, for example, aluminum, an aluminum alloy, etc. The thickness of the positive electrode core 241 is, for example, about 3 μm or more, and preferably about 5 μm or more. The thickness of the positive electrode core 241 is, for example, about 30 μm or less, and preferably about 20 μm or less.

[0139] The positive electrode active material layer 242 includes a positive electrode active material. The positive electrode active material layer 242 may include a binder (PVDF or the like) and a conductive material (carbon material or the like) in addition to the positive electrode active material. The positive electrode active material is preferably a lithium transition metal composite oxide or the like. The positive electrode active material may be a mixture of multiple types of materials.

[0140] The thickness of the positive electrode active material layer 242 is preferably, for example, about 30 μm or more, more preferably about 40 μm or more, and even more preferably about 50 μm or more. The thickness of the positive electrode active material layer 242 is preferably, for example, about 500 μm or less, and more preferably about 300 μm or less.

[0141] The positive electrode protective layer 243 is a layer having a higher electrical resistance than the positive electrode active material layer 242. The positive electrode protective layer 243 contains substantially no positive electrode active material or contains only a trace amount of positive electrode active material. For example, the mass of the positive electrode active material relative to the total mass of the positive electrode protective layer 243 is about 5% or less, and preferably about 1% or less.

[0142] The positive electrode protective layer 243 preferably contains inorganic particles (such as alumina, boehmite, etc.). The positive electrode protective layer 243 preferably contains inorganic particles and a binder. The positive electrode protective layer 243 preferably contains about 50 mass % or more of inorganic particles. The positive electrode protective layer 243 may be an insulating resin layer, or may contain a conductive carbon material.

[0143] The positive electrode protective layer 243 is preferably formed on the positive electrode core 241 along the end of the portion where the positive electrode active material layer 242 is formed. The positive electrode protective layer 243 is preferably disposed so as to face the end of the negative electrode active material layer 212 via a separator (insulating sheet). This makes it possible to suppress a short circuit between the positive electrode core 241 and the end of the negative electrode active material layer 212.

[0144] The thickness of the positive electrode protective layer 243 is preferably thinner than the thickness of the positive electrode active material layer 242. The thickness of the positive electrode protective layer 243 is preferably about 10 μm or more, more preferably about 20 μm or more, and even more preferably about 30 μm or more. The thickness of the positive electrode protective layer 243 is preferably, for example, about 200 μm or less, more preferably about 100 μm or less, and even more preferably about 50 μm or less.

[0145] In the negative electrode plate, the negative electrode core 211 is preferably made of a metal including, for example, copper or a copper alloy, and more preferably made of a metal foil.

[0146] The negative electrode core 211 has a thickness of, for example, about 3 μm or more, and preferably about 5 μm or more. The negative electrode core 211 has a thickness of, for example, about 30 μm or less, and preferably about 20 μm or less.

[0147] The negative electrode active material layer 212 includes a negative electrode active material. In addition to the negative electrode active material, the negative electrode active material layer 212 may include a binder (SBR, CMC, etc.) and a conductive material (carbon material, etc.). The negative electrode active material is preferably a carbon material such as graphite, or a silicon material such as SiO or SiC. The negative electrode active material may be a mixture of multiple types of materials.

[0148] The thickness of the negative electrode active material layer 212 is preferably, for example, about 50 μm or more, more preferably about 60 μm or more, and even more preferably about 70 μm or more. The thickness of the negative electrode active material layer 212 is preferably, for example, about 500 μm or less, and more preferably about 300 μm or less.

[0149] (Modifications of the electrode body 200) Fig. 25 is a schematic diagram showing the structure of an electrode body 200 according to a modified example. As shown in Fig. 25, in the main body of the electrode body 200, the positive electrode protective layer 243 may protrude toward the positive electrode tab groups 250, 280 side beyond the separator 800 provided between the positive electrode plate 240 and the negative electrode plate 210.

[0150] (Dimensional Relationship Between Electrode Assembly 200 and Separator 800) Next, the dimensional relationship between the electrode assembly 200 and the separator 800 will be described with reference to FIGS.

[0151] 26, at the end on the positive electrode tab groups 250, 280 side in the X direction (first direction), the separator 800 preferably protrudes by a distance B from the positive electrode protection layer 243. In this case, when the electrode body 200 is inserted into the case body 110, in the electrode body 200 moving in the +X direction, the separator 800 having a thickness of, for example, about 16 μm comes into contact with other members such as the inner wall of the case body 110 before the positive electrode protection layer 243, and the negative electrode active material layer 212 can be protected more effectively.

[0152] The protruding amount (B) of separator 800 is preferably about 2.0 mm or more and 4.0 mm or less. By setting the protruding amount (B) to about 4.0 mm or less, it is possible to prevent separator 800 from covering the welding portion between case body 110 and sealing plate 130, which may cause an impediment to welding.

[0153] 27, at both ends in the Z direction (second direction), the separator 800 preferably protrudes by distances H1 and H2 from the ends of the negative electrode active material layer 212. In this case, when the electrode body 200 is inserted into the case body 110, the separator 800 comes into contact with other members, such as the inner wall of the case body 110, before the negative electrode active material layer 212 does, and the negative electrode active material layer 212 can be protected more effectively.

[0154] The protrusion amount (H1, H2) of the separator 800 is preferably about 0.1 mm or more and 2.0 mm or less. By setting the protrusion amount (H1, H2) to about 2.0 mm or less, it is possible to suppress a situation in which the separator 800 and the inner wall of the case body 110 interfere with each other, increasing friction, preventing the electrode body 200 from being smoothly inserted, and thus damaging the negative electrode active material layer 212.

[0155] (Dimensional relationship between positive electrode tab group and negative electrode tab group) Next, the dimensional relationship between the positive electrode tab groups 250, 280 and the negative electrode tab groups 220, 270 will be described with reference to FIGS.

[0156] Fig. 28 shows a state in which the longest positive electrode tab 260 among the multiple positive electrode tabs 260 included in the positive electrode tab groups 250, 280 is stretched without being curved. In the state shown in Fig. 28, there is a distance L1 between the base of the longest positive electrode tab 260 and a joint 421 (joint portion) with the current collector 420 (first other member).

[0157] Fig. 29 shows a state in which the longest negative electrode tab 230 is stretched without being curved among the multiple negative electrode tabs 230 included in the negative electrode tab groups 220, 270. In the state shown in Fig. 29, there is a distance L2 from the base of the longest negative electrode tab 230 to the joints 411, 431 (joints) with the current collectors 410, 430 (second other members).

[0158] It should be noted that the "first other member" and the "second other member" are not limited to the current collector 420 and the current collectors 410, 430. When the positive electrode tab groups 250, 280 and the negative electrode tab groups 220, 270 are directly joined to a member (such as an electrode terminal or a sealing plate) other than the current collector 420 and the current collectors 410, 430, the directly joined member becomes the "first other member" and the "second other member".

[0159] When comparing the distance L1 from the base of the positive electrode tab 260 shown in FIG. 28 to the joint point 421 with the current collector 420, with the distance L2 from the base of the negative electrode tab 230 shown in FIG. 29 to the joint points 411, 431 with the current collectors 410, 430, it is preferable that L1>L2.

[0160] In this manner, first, the relatively short negative electrode tab group 220, 270 is connected to the sealing plate 120, then the electrode body 200 is inserted into the case body 110 from the positive electrode tab group 250, 280 side, and then the relatively long positive electrode tab group 250, 280 can be connected to the sealing plate 130. Since the positive electrode tab group 250, 280 that is connected to the sealing plate 130 after the electrode body 200 insertion step is relatively long, the connection work is easy to perform, and the secondary battery 1 can be assembled more stably. However, the present technology is not limited to the example where L1>L2, and L1 <L2であってもよいし、L1=L2であってもよい。

[0161] In the above example, a case was described in which the positive electrode tab groups 250, 280 include multiple positive electrode tabs 260, and the negative electrode tab groups 220, 270 include multiple negative electrode tabs 230. However, the positive electrode tabs 260 and negative electrode tabs 230 are not limited to multiple, and for example, when a wound electrode body is adopted, one electrode body may be provided with one positive electrode tab or one negative electrode tab.

[0162] (Modification of Secondary Battery 1) Fig. 30 is a cross-sectional view showing the configuration of a secondary battery according to a modified example. As shown in Fig. 30, in the secondary battery according to the modified example, tip portions 222, 272 of negative electrode tab group 220 and negative electrode tab group 270 are bent in the same direction in the Y direction.

[0163] Thereafter, the first electrode body 201 and the second electrode body 202 are inserted into the case body, and the sealing plate 120 is abutted against the case body. As a result, the negative electrode tab group 220 and the negative electrode tab group 270 are curved in the same direction so that the tip portions 222, 272 face the same direction. In order to make it easier to curve the tip portions 222, 272 in the same direction, the third part 630 of the spacer 600 is provided between the negative electrode tab group 220 and the negative electrode tab group 270.

[0164] By making the tip portions 222, 272 of the negative electrode tab group 220 and the negative electrode tab group 270 curved in the same direction in the Y direction, it is possible to prepare the first electrode body 201 to which the current collector 410 is attached and the second electrode body 202 to which the current collector 430 is attached in the same configuration. This makes it possible to configure the first electrode body 201 to which the current collector 410 is attached and the second electrode body 202 to which the current collector 430 is attached as one type, thereby simplifying the manufacturing process.

[0165] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0166] 1 secondary battery, 100 case, 110 case body, 111 first side portion, 112, 112A, 112B second side portion, 113, 114 opening, 115 joint portion, 120, 130 sealing plate, 134 liquid inlet, 150 gas exhaust valve, 200 electrode body, 201 first electrode body, 202 second electrode body, 205 first end portion, 206 second end portion, 207 third end portion, 208 fourth end portion, 210 negative electrode plate, 211 negative electrode core body, 212 negative electrode active material layer, 220, 270 negative electrode tab group, 221, 251, 271, 281 curved portion, 222, 252, 272, 282 tip portion, 230 negative electrode tab, 240 positive electrode plate, 241 Positive electrode core, 242 positive electrode active material layer, 243 positive electrode protective layer, 250, 280 positive electrode tab group, 260 positive electrode tab, 300 electrode terminal, 301 negative electrode terminal, 302 positive electrode terminal, 303, 304 plate-shaped member, 400, 410, 420, 430, 440, 450 current collector, 400A negative electrode current collector, 400B positive electrode current collector, 411, 421, 431 joint portion, 510, 520, 530 insulating member, 600 spacer, 610 first part, 620 second part, 630 third part, 700 insulating sheet, 800 separator.

Claims

1. A step of preparing an electrode assembly including a positive electrode plate and a negative electrode plate; and housing the electrode body in a case. the case includes a case body having a first opening at one end and a second opening at the other end, a first sealing plate that seals the first opening, and a second sealing plate that seals the second opening, The step of housing the electrode body in the case includes inserting the electrode body into the case body from the first opening, the electrode body has a main body, a positive electrode tab located on the second sealing plate side of the main body and provided on the positive electrode plate, and a negative electrode tab located on the first sealing plate side of the main body and provided on the negative electrode plate, the positive electrode plate includes a positive electrode core, a positive electrode active material layer formed on the positive electrode core, and a positive electrode protective layer formed on the positive electrode core, In the positive electrode plate, the positive electrode protective layer is located closer to the positive electrode tab than the positive electrode active material layer, The negative electrode plate includes a negative electrode core and a negative electrode active material layer formed on the negative electrode core, a positive electrode protection layer protruding toward the positive electrode tab side beyond the end of the negative electrode active material layer at an end of the main body portion of the electrode body on the positive electrode tab side.

2. The method for manufacturing a secondary battery according to claim 1 , wherein the electrode assembly is inserted into the case body from an end of the electrode assembly on which the positive electrode tab is disposed.

3. The method for manufacturing a secondary battery according to claim 2 , wherein the electrode assembly is inserted into the case body after the negative electrode tab and the first sealing plate are connected to each other.

4. The method for manufacturing a secondary battery according to claim 2 , further comprising the steps of: connecting the positive electrode tab and the second sealing plate after inserting the electrode body into the case body.

5. 5 . The method for producing a secondary battery according to claim 1 , further comprising the step of electrically connecting the negative electrode tab to the negative electrode terminal attached to the first sealing plate via a negative electrode current collector.

6. 5 . The method for producing a secondary battery according to claim 1 , further comprising the step of electrically connecting the positive electrode tab to a positive electrode terminal attached to the second sealing plate via a positive electrode current collector.

7. The positive electrode tab is joined to a first other member, and the negative electrode tab is joined to a second other member, 5. The method for manufacturing a secondary battery according to claim 1, wherein a distance from a base of the positive electrode tab to a joint between the positive electrode tab and the first other member is longer than a distance from a base of the negative electrode tab to a joint between the negative electrode tab and the second other member.

8. An electrode assembly including a positive electrode plate and a negative electrode plate; A case for accommodating the electrode body, the case includes a case body having a first opening at one end and a second opening at the other end, a first sealing plate that seals the first opening, and a second sealing plate that seals the second opening, The positive electrode plate has a positive electrode tab at an end portion on the second sealing plate side, the negative electrode plate has a negative electrode tab at an end portion on the first sealing plate side, the positive electrode plate includes a positive electrode core, a positive electrode active material layer formed on the positive electrode core, and a positive electrode protective layer formed on the positive electrode core, In the positive electrode plate, the positive electrode protective layer is located closer to the positive electrode tab than the positive electrode active material layer, The negative electrode plate includes a negative electrode core and a negative electrode active material layer formed on the negative electrode core, a positive electrode protection layer protruding toward the positive electrode tab side beyond an end of the negative electrode active material layer in the electrode assembly;

9. The positive electrode tab is joined to a first other member, and the negative electrode tab is joined to a second other member, The secondary battery according to claim 8 , wherein a distance from a base of the positive electrode tab to a joint between the positive electrode tab and the first other member is longer than a distance from a base of the negative electrode tab to a joint between the negative electrode tab and the second other member.

10. 10. The secondary battery according to claim 8, wherein the electrode assembly is a laminated electrode assembly including a plurality of the positive electrode plates and a plurality of the negative electrode plates.

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