Secondary battery and battery pack

Abstract

The present application relates to a secondary battery and a battery pack. A separator (600) has a pair of first portions (610) at both end sides in a second direction and a second portion (620) between the pair of first portions (610) in the second direction, a flat surface (600A) of the separator (600) is continuously formed from one of the pair of first portions (610) to the other, and the thickness of the pair of first portions (610) in a direction orthogonal to the flat surface (600A) is greater than that of the second portion (620) at least in a part of a first direction.

Description

Technical Field

[0001] This technology relates to secondary batteries and battery packs. Background Technology

[0002] Japanese Patent No. 4537353 discloses a square battery with a positive terminal on one side of the battery casing and a negative terminal at the other end. Summary of the Invention

[0003] The requirement is to suppress metal deposition in secondary batteries. When a battery pack is constructed from secondary batteries in a square-shaped outer can, the pressure load tends to be relatively small near the end edges of the roughly rectangular outer can. This deviation in pressure load creates a resistance difference within the electrode body, easily leading to metal deposition. Therefore, it is necessary to effectively suppress metal deposition in areas with relatively small pressure loads. From this perspective, there is still room for improvement in conventional secondary batteries.

[0004] The purpose of this technology is to provide a secondary battery with suppressed metal deposition and a battery pack having the secondary battery.

[0005] This technology provides the following secondary batteries and battery packs.

[0006] [1] A secondary battery, comprising: an electrode body having a pair of main surfaces; a spacer having a flat surface facing one of the pair of main surfaces; and an outer can having a square shape for housing the electrode body and the spacer, the outer can having a pair of first surfaces facing the pair of main surfaces, a pair of second surfaces substantially orthogonal to the first surfaces, and a pair of third surfaces substantially orthogonal to the first and second surfaces, the area of ​​the first surface being larger than the area of ​​the second surface and the area of ​​the third surface, the first surface having a surface including The spacer has a generally rectangular shape including a pair of first end edges extending along a first direction and a pair of second end edges extending along a second direction that is generally orthogonal to the first direction, the pair of first end edges being longer than the pair of second end edges, the spacer having a pair of first portions located at both ends in the second direction and a second portion located between the pair of first portions in the second direction, the flat surface of the spacer being continuously formed from one of the pair of first portions to the other, and the thickness of the pair of first portions in at least a portion of the first direction in a direction orthogonal to the flat surface being greater than that of the second portions.

[0007] [2] According to the secondary battery of [1], wherein the thickness of the pair of first portions in at least the central portion in the first direction is greater than that of the second portion in the direction orthogonal to the flat surface.

[0008] [3] According to the secondary battery of [1] or [2], wherein the thickness of the pair of first portions in the entire region of the first direction in the direction orthogonal to the flat surface is greater than that of the second portion.

[0009] [4] The secondary battery according to any one of [1] to [3], wherein the spacer extends to the outside of the electrode body in the second direction.

[0010] [5] The secondary battery according to any one of [1] to [4] further comprises an insulating member disposed on the outside of the electrode body.

[0011] [6] A battery pack, wherein the battery pack comprises: a plurality of secondary batteries, the plurality of secondary batteries being any one of [1] to [5], arranged in a third direction orthogonal to the first direction and the second direction; and a battery spacer disposed between the plurality of secondary batteries, wherein, when viewed from the third direction, the area of ​​the battery spacer is smaller than the area of ​​the first surface of the outer can.

[0012] The above and other objects, features, aspects and advantages of the present invention will become clear from the following detailed description relating to the invention, which will be understood in conjunction with the accompanying drawings. Attached Figure Description

[0013] Figure 1 This is a front view showing the structure of the secondary battery according to the embodiment.

[0014] Figure 2 This indicates viewing from the direction of arrow II. Figure 1 The diagram shows the state of the secondary battery.

[0015] Figure 3 This indicates viewing from the direction of arrow III. Figure 1 The diagram shows the state of the secondary battery.

[0016] Figure 4 This indicates viewing from the direction of arrow IV. Figure 1 The diagram shows the state of the secondary battery.

[0017] Figure 5 This indicates viewing from the direction of arrow V. Figure 1 The diagram shows the state of the secondary battery.

[0018] Figure 6 yes Figure 1 The image shows a front cross-sectional view of a secondary battery.

[0019] Figure 7 This is a cross-sectional view of the negative electrode plate.

[0020] Figure 8 This is the front view of the negative electrode plate.

[0021] Figure 9 This is a cross-sectional view of the positive electrode plate.

[0022] Figure 10 This is the front view of the positive electrode plate.

[0023] Figure 11 It is a three-dimensional diagram showing the state where a sealing plate is installed on the current collector on the positive side.

[0024] Figure 12 It is a three-dimensional diagram showing the structure of a secondary battery.

[0025] Figure 13 This is a diagram showing the secondary battery and the battery spacer adjacent to it, viewed from the stacking direction.

[0026] Figure 14 This is a diagram used to illustrate the flat surface of a stacked electrode.

[0027] Figure 15 This is a diagram used to illustrate the flat surface of a wound electrode.

[0028] Figure 16 It is a cross-sectional view of the electrode body and spacers housed in the outer can.

[0029] Figure 17 This is a cross-sectional view showing an example of the shape of the spacer adjacent to the main surface of the electrode body.

[0030] Figure 18 This is a cross-sectional view showing another example of the shape of the spacer adjacent to the main surface of the electrode body.

[0031] Figure 19 This is another example of a cross-sectional view showing the shape of a spacer adjacent to the main surface of the electrode body.

[0032] Figure 20 This is the front view of the electrode.

[0033] Figure 21 This is a front view showing the state where spacers are arranged on the main surface of the electrode body.

[0034] Figure 22 This is a front sectional view showing the state in which the electrode body and spacer are inserted into the housing body. Detailed Implementation

[0035] The following describes the implementation of this technology. It should be noted that the same or equivalent parts are labeled with the same reference numerals, and sometimes the description is not repeated.

[0036] It should be noted that, in the embodiments described below, when numbers, quantities, etc., are mentioned, the scope of this technology is not necessarily limited to those numbers, quantities, etc., unless specifically stated otherwise. Furthermore, in the embodiments described below, each constituent element is not necessarily essential to this technology, unless specifically stated otherwise. Additionally, this technology is not limited to technologies that must achieve all the effects mentioned in this embodiment.

[0037] It should be noted that in this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a structure is included, other structures besides that structure may be included, or they may not be included.

[0038] Furthermore, in this specification, when using geometric terms and terms indicating positional / directional relationships, such as "parallel," "orthogonal," "tilted at 45°," "coaxial," and "along," these terms are permissible with manufacturing errors or slight variations. In this specification, when using terms indicating relative positional relationships such as "upper side" and "lower side," these terms are used to indicate the relative positional relationship in a given state. Depending on the orientation of each mechanism (e.g., flipping the entire mechanism upside down), the relative positional relationship can be flipped or rotated to any angle.

[0039] Furthermore, the dimensions of the components illustrated in this specification, such as width, length, and diameter, are not limited to those shown in the illustrations and may be appropriately changed. In this specification, structures are sometimes labeled with ordinal numbers such as "first" or "second," but these ordinal numbers, except where explicitly specified, do not imply priority or order.

[0040] In this instruction manual, "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 instruction manual, "electrode" can be collectively referred to as the positive electrode and the negative electrode. Additionally, "electrode plate" can be collectively referred to as the positive plate and the negative plate.

[0041] In this manual, "battery" can be used in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). However, the use of "battery" is not limited to vehicle applications.

[0042] In this specification, the X direction (first direction) is sometimes referred to as the "width direction" of the secondary battery, electrode body and housing body, and similarly, the Z direction (second direction) is sometimes referred to as the "height direction" of the secondary battery, electrode body and housing body, and similarly, the Y direction (third direction) is sometimes referred to as the "thickness direction" of the secondary battery, electrode body and housing body.

[0043] (The overall structure of a secondary battery)

[0044] Reference Figures 1 to 6 The overall structure of the secondary battery 1 is described below. The secondary battery 1 includes a casing 100 (outer can), electrode bodies 200, electrode terminals 300, and current collector 400. The casing 100 includes a casing body 110, a sealing plate 120, and a sealing plate 130.

[0045] When constructing a battery pack including secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 can be constrained in the stacking direction (Y direction) by a limiting member to form a battery module, or the battery pack can be directly supported on the side of the battery pack housing without using a limiting member.

[0046] The casing body 110 is composed of a cylindrical, preferably square-cylindrical, component. This allows for the production of a secondary battery 1 with a square-shaped casing 100. The casing body 110 is made of metal. Specifically, it is made of aluminum, aluminum alloy, iron, or an iron alloy.

[0047] like Figure 1 as well as Figure 2 As shown, sealing plates 120 and 130 are respectively provided at both ends of the housing body. The housing body 110 is constructed, for example, by having the end edges of a bent plate-like component abut against each other. Figure 2 The illustrated joint 115 is joined together (e.g., by energy line irradiation such as laser welding) to form a square tube shape. The corners of the "square tube" may also have an R-shape (rounded corner shape).

[0048] In this embodiment, the housing body 110 is formed such that its width (X direction) is longer than its thickness (Y direction) and height (Z direction) of the secondary battery 1. The width of the housing body 110 in the X direction is preferably 300 mm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The height of the housing body 110 in the Z direction is preferably 100 mm or less. This allows for the construction of a relatively low-height (low-height) secondary battery 1, for example, improving vehicle mounting capability. However, the size of the secondary battery 1 is not limited to the above-described range.

[0049] The housing body 110 includes a first side surface 111 (first surface) and a second side surface 112 (second surface). The first side surface 111 is composed of a pair of first side surface portions 111A and 111B, and the second side surface 112 is composed of a pair of second side surface portions 112A and 112B. The first side surface portions 111A and 111B form part of the side surface of the housing 100. The pair of second side surface portions 112A and 112B form the bottom surface and the top surface of the housing 100. The first side surface portions 111 and 112 are arranged to intersect each other (approximately orthogonal). The first side surface portions 111 and 112 are connected at their respective ends.

[0050] like Figure 5 As shown, a gas discharge valve 150 is provided on one of the second side surfaces 112A. The gas discharge valve 150 extends along the width direction (X direction) of the secondary battery 1. The gas discharge valve 150 extends along the X direction to a degree that it does not extend from the center of the housing body 110 in the X direction to both ends. The shape of the gas discharge valve 150 can be appropriately modified.

[0051] The thickness of the plate-shaped component at the gas discharge valve 150 is thinner than the thickness of the plate-shaped components other than the gas discharge valve 150 in the housing body 110. As a result, when the pressure inside the housing 100 reaches a predetermined value or higher, the gas discharge valve 150 breaks first compared to other parts in the housing body 110, venting the gas inside the housing 100 to the outside.

[0052] like Figure 2 As shown, a joining portion 115 is formed on the other side of the second side portion 112, the second side portion 112B. The joining portion 115 extends along the width direction (X direction) of the secondary battery 1. At the joining portion 115, the end edges of the plate-shaped members constituting the housing body 110 are joined together.

[0053] like Figure 3 As shown, an opening 113 (first opening) is provided at one end of the housing body 110 in a first direction (X direction). The opening 113 is sealed by a sealing plate 120 (first sealing plate). A joint portion 115 is formed in the opening 113, and the opening 113 is sealed. The opening 113 and the sealing plate 120 have a generally rectangular shape with the short side in the Y direction and the long side in the Z direction. The generally rectangular shape includes a rectangular shape or a shape with rounded corners, etc., that is substantially rectangular.

[0054] A negative terminal 300A is provided on the sealing plate 120. The position of the negative terminal 300A can be changed as appropriate.

[0055] like Figure 4As shown, an opening 114 (second opening) is provided at the end of the housing body 110 on the opposite side in the X direction. That is, opening 114 is located at the end opposite to opening 113, and openings 113 and 114 face each other. Opening 114 is sealed by a sealing plate 130 (second sealing plate). A joint portion 115 is formed in opening 114, and opening 114 is sealed. Opening 114 and sealing plate 130 have a generally rectangular shape with the short side in the Y direction and the long side in the Z direction.

[0056] A positive terminal 300B and a liquid injection hole 140 are provided on the sealing plate 130. The positions of the positive terminal 300B and the liquid injection hole 140 can be changed as appropriate. The liquid injection hole 140 is sealed by a sealing component (not shown). As a sealing component, blind rivets and other metal components can be used, for example.

[0057] Sealing plates 120 and 130 are made of metal. Specifically, sealing plates 120 and 130 are made of aluminum, aluminum alloy, iron, or iron alloy.

[0058] Sealing plates 120 and 130 (third side) form part of housing 100. Sealing plates 120 and 130 are arranged in a manner that intersects (approximately orthogonal) with respect to the first side portion 111 and the second side portion 112.

[0059] In the housing 100, the area (first area) of each of the pair of first side portions 111 (first surfaces) is larger than the area (second area) of each of the pair of second side portions 112 (second surfaces) and the area (third area) of each of the sealing plates 120 and 130 (third surfaces).

[0060] The negative terminal 300A is electrically connected to the negative terminal of the electrode body 200. The negative terminal 300A is mounted on the sealing plate 120, i.e., the housing 100. The positive terminal 300B is electrically connected to the positive terminal of the electrode body 200. The positive terminal 300B is mounted on the sealing plate 130, i.e., the housing 100.

[0061] The negative terminal 300A is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. The positive terminal 300B is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy.

[0062] The electrode body 200 is a flat electrode body with the negative electrode plate 210 and positive electrode plate 220 (described later) stacked on top of each other. Specifically, the electrode body 200 is a stacked electrode body in which multiple negative electrode plates 210 and multiple positive electrode plates 220 are alternately stacked with a separator. The separator can be formed by folding a strip-shaped insulating sheet component or by individually setting multiple insulating sheets. In this specification, "electrode body" is not limited to a stacked electrode body; it can also be a wound electrode body formed by winding strip-shaped negative electrode plates and strip-shaped positive electrode plates together with a strip-shaped separator. The separator can be made of, for example, a microporous membrane of polyolefin.

[0063] like Figure 6 As shown, the housing 100 houses the electrode body 200. The electrode body 200 is housed within the housing 100 with its long side parallel to the X direction. Specifically, one or more stacked electrode bodies are housed in the housing 100 together with an electrolyte (not shown). As the electrolyte (non-aqueous electrolyte), for example, an electrolyte in which LiPF6 is dissolved in a non-aqueous solvent can be used. A solid electrolyte can also be used instead of the electrolyte.

[0064] The electrode body 200 includes a generally rectangular main body, a negative electrode tab group 200A, and a positive electrode tab group 200B.

[0065] The main body is composed of a negative electrode plate 210 and a positive electrode plate 220, which will be described later. The negative electrode tab assembly 200A is located at the end of the main body on one side (the sealing plate 120 side) of the electrode body 200 in the X direction. The positive electrode tab assembly 200B is located at the end of the main body on the other side (the sealing plate 130 side) of the electrode body 200 in the X direction.

[0066] The negative electrode tab group 200A and the positive electrode tab group 200B are formed to protrude from the central part of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0067] The current collector 400 includes a negative current collector 400A and a positive current collector 400B. The negative current collector 400A and the positive current collector 400B are each composed of plate-shaped components. The electrode body 200 is electrically connected to the negative terminal 300A and the positive terminal 300B via the current collector 400.

[0068] The negative current collector 400A is disposed on the sealing plate 120 through a resin insulating component. The negative current collector 400A is electrically connected to the negative electrode tab assembly 200A and the negative terminal 300A. The negative current collector 400A is made of a conductive material (more specifically, a metal), such as copper or a copper alloy.

[0069] The positive current collector 400B is disposed on the sealing plate 130 through a resin insulating component. The positive current collector 400B is electrically connected to the positive electrode tab assembly 200B and the positive terminal 300B. The positive current collector 400B is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. The positive electrode tab assembly 200B can also be electrically connected to the sealing plate 130 directly or via the positive current collector 400B. In this case, the sealing plate 130 can also function as the positive terminal 300B.

[0070] (Structure of electrode body 200)

[0071] like Figure 7 as well as Figure 8 As shown, the negative electrode plate 210 includes a negative electrode core 211 and a negative electrode active material layer 212. At one end of the negative electrode plate 210 in the width direction, a negative electrode tab 200A0 formed by the negative electrode core 211 is provided. When stacking the negative electrode plates 210, multiple negative electrode tabs 200A0 are stacked to form a negative electrode tab group 200A. The negative electrode tab group 200A is electrically connected to the negative electrode. The length of each negative electrode tab 200A0 in the protruding direction of the multiple negative electrode plates 210 is appropriately adjusted considering the connection state between the negative electrode tab group 200A and the negative electrode current collector 400A. The shape of the negative electrode tab 200A0 is not limited to... Figure 8 The illustrated shape.

[0072] like Figure 9 as well as Figure 10 As shown, the positive electrode plate 220 includes a positive electrode core 221, a positive electrode active material layer 222, and a positive electrode protective layer 223. At one end of the positive electrode plate 220 in the width direction, a positive electrode tab 200B0 composed of the positive electrode core 221 is provided. When stacking the positive electrode plates 220, multiple positive electrode tabs 200B0 are stacked to form a positive electrode tab assembly 200B. The positive electrode tab assembly 200B is electrically connected to the positive electrode. The length of each positive electrode tab 200B0 in the protruding direction of the multiple positive electrode plates 220 is appropriately adjusted considering the connection state between the positive electrode tab assembly 200B and the positive current collector 400B. The shape of the positive electrode tab 200B0 is not limited to... Figure 10 The illustrated shape.

[0073] A positive electrode protection layer 223 is provided at the root of the positive electrode tab 200B0. However, it is not always necessary to provide a positive electrode protection layer 223 at the root of the positive electrode tab 200B0.

[0074] (Containment of electrode body 200)

[0075] The electrode body 200, with the positive electrode tab group 200B side as the front, is inserted into the housing body 110 through the opening 113. For example... Figure 11As shown, a spacer 500 is provided between the electrode body 200 and the sealing plate 130 on the positive electrode side. A spacer 500 is also provided between the electrode body 200 and the sealing plate 120 on the negative electrode side, similar to the one on the positive electrode side.

[0076] Alternatively, the electrode body 200 can be electrically connected to the negative terminal 300A before being inserted into the housing body 110. After the electrode body 200 is inserted into the housing body 110, it can be electrically connected to the positive terminal 300B.

[0077] After inserting the electrode body 200 into the housing body 110, as Figure 12 As shown, sealing plates 120 and 130 are joined to the housing body 110. Sealing plate 120 seals the opening 113 of the housing body 110, and sealing plate 130 seals the opening 114 of the housing body 110. Thus, the electrode body 200 is housed in the housing 100.

[0078] (Structure of the battery pack)

[0079] like Figure 13 As shown, the first side portion 111 of the housing body 110 has a generally rectangular shape including a pair of first end edges 101 extending in the X direction and a pair of second end edges 102 extending in the Z direction. Here, the pair of first end edges 101 are longer than the pair of second end edges 102. That is, the first side portion 111 has a generally rectangular shape with the X direction being the long side direction and the Z direction being the short side direction.

[0080] In the configuration of the battery pack, multiple secondary batteries 1 are arranged side-by-side in the Y direction. Battery spacers 2 are disposed between the multiple secondary batteries 1. For example... Figure 13 As shown, when viewed from the Y direction, the area of ​​the battery spacer 2 is smaller than the area of ​​the first side portion 111 of the housing body 110. Preferably, the area of ​​the battery spacer 2 is smaller than the area of ​​the flat surface 2000 of the electrode body 200.

[0081] When the electrode body 200 is a stacked electrode body, such as Figure 14 As shown, a flat surface 2000 is formed over the entire area of ​​the electrode body 200.

[0082] In the case where the electrode body 200 is a wound type electrode body (with the winding shaft extending along the X direction), such as Figure 15 As shown, in the Z direction, a flat surface 2000 is formed in the region other than the circumferential portions formed at both ends of the electrode body 200.

[0083] (Structure of spacer 600)

[0084] like Figure 16As shown, the electrode body 200 has a pair of main surfaces 230. The main surfaces 230 extend in a direction orthogonal to the Y direction. In the Y direction, spacers 600 are provided on both sides of the electrode body 200. The spacers 600 are insulating plate-shaped components. The spacers 600 and the electrode body 200 are housed together in the housing 100. The spacers 600 may also be provided only on one side of the electrode body 200 in the Y direction.

[0085] Imagine Figure 16 The electrode body 200 shown is a stacked electrode body, with the main surface 230 corresponding to the flat surface 2000. In the case where the electrode body 200 is a wound electrode body, the portion forming the flat surface 2000 is equivalent to... Figure 16 The electrode body 200 is shown in the figure.

[0086] The spacer 600 has a flat surface 600A facing the main surface 230. Figure 16 In the example, the flat surface 600A of the spacer 600 on the left side of the figure faces the main surface 231 on the left side of the electrode body 200, and the flat surface 600A of the spacer 600 on the right side of the figure faces the main surface 232 on the right side of the electrode body 200.

[0087] The spacer 600 is made of an insulating material. Preferably, the spacer 600 is made of resin. For example, polyethylene, polypropylene, and resins having the same degree of elasticity as these can be used as the resin constituting the spacer 600. The spacer 600 may also be made of resin tape or cut resin sheets, etc.

[0088] The spacer 600 can be positioned by fixing the flat surface 600A of the spacer 600 to the electrode body 200 or to an electrode body holder (insulating member) provided on the outside of the electrode body 200. Methods for fixing the spacer 600 to the electrode body 200 or the electrode body holder include, for example, tape-based bonding, adhesive-based bonding, heat fusion, or ultrasonic bonding.

[0089] The spacer 600 has a first portion 610 located at both ends in the Z direction and a second portion 620 located at the center in the Z direction. The second portion 620 is located between the pair of first portions 610 in the Z direction (second direction). The thickness of the first portion 610 in the Y direction (first thickness) is greater than the thickness of the second portion 620 in the Y direction (second thickness).

[0090] exist Figure 16In this example, a second portion 620 with a relatively smaller thickness than the first portion 610 is formed by forming an arc-shaped recess 630 between the two ends of the first portion 610 located in the Z direction. The recess 630 is formed on the surface opposite to the flat surface 600A. The flat surface 600A is formed continuously from one of the pair of first portions 610 formed at both ends in the Z direction (the upper first portion 610 in the figure) to the other (the lower first portion 610 in the figure).

[0091] The maximum thickness (T1) of the first portion 610 is preferably 0.5 mm or more greater than the minimum thickness (T2) of the second portion 620. The maximum thickness (T1) of the first portion 610 is preferably 2.5 mm or less, more preferably 1.5 mm or less. By making the maximum thickness of the first portion 610 a predetermined value or more, the effect of suppressing metal precipitation described later can be improved. By making the maximum thickness of the first portion 610 a predetermined value or less, the reduction in space efficiency within the housing 100 can be suppressed.

[0092] The minimum thickness (T2) of the second part 620 is preferably between 0.05 mm and 0.5 mm, more preferably around 0.1 mm. By ensuring that the minimum thickness of the second part 620 is at or above a specified value, the strength of the spacer 600 can be ensured. By ensuring that the minimum thickness of the second part 620 is below a specified value, the reduction in space efficiency within the housing 100 can be suppressed.

[0093] However, the thickness of the first part 610 and the second part 620 is not limited to the above range.

[0094] The spacer 600 preferably has a spacer in its entire region in the X direction (first direction). Figure 16 The cross-sectional shape shown. However, the spacer 600 may also have a portion in the X direction that is similar to... Figure 16 Different cross-sectional shapes. Preferably, at least in the central portion of the spacer 600 in the X direction, the thickness of the first portion 610 is greater than the thickness of the second portion 620.

[0095] exist Figure 16 In the example, the spacer 600 is formed to be longer than the electrode body 200 in the Z direction, reaching the outer side of the electrode body 200 in the Z direction. Therefore, even if the electrode body 200 moves slightly in the Z direction within the housing 100, the first portion 610 of the spacer 600 can reliably overlap with the electrode body 200. When the electrode body 200 is a stacked electrode body, the spacer 600 can also reach, for example, a position approximately 2.5 mm outward from the electrode body 200 both vertically and horizontally in the Z direction. However, the spacer 600 can be positioned in the same area as the electrode body 200 in the Z direction, or it can be formed to be slightly shorter than the electrode body 200 in the Z direction.

[0096] like Figures 17 to 19 As shown, the cross-sectional shape of the spacer 600 can be appropriately modified. The first portion 610 preferably has a shape that thins towards the center in the Z direction (e.g., a straight conical shape or an arc shape), but the thickness of the first portion 610 can also be approximately constant.

[0097] Specifically, such as Figure 17 As shown, the cross-sectional shape of the arc-shaped recess 630 can also be set in the entire area in the Z direction, such as... Figure 18 As shown, it can also be a cross-sectional shape in which the thickness of the first portion 610 of the end spacer 600 in the Z direction is approximately constant. For example... Figure 19 As shown, it can also be a cross-sectional shape with a roughly rectangular recess 630.

[0098] Next, use Figures 20 to 22 The dimensional relationship between the electrode body 200 and the spacer 600 is explained.

[0099] exist Figures 20 to 22 In, also with Figure 16 Similarly, we can assume that electrode body 200 is a stacked electrode body. In the case where electrode body 200 is a wound electrode body, the portion forming the flat surface 2000 is equivalent to... Figures 20 to 22 The electrode body 200 is shown in the figure.

[0100] In addition, Figure 21 , Figure 22 In the first part 610, there is a region having a thickness that is 0.5 mm greater than the minimum thickness of the second part 620.

[0101] like Figure 20 As shown, the main body of the electrode body 200 (the rectangular portion excluding the negative electrode tab group 200A and the positive electrode tab group 200B) has a shape in which the dimension in the X direction (L0) is larger than the dimension in the Z direction (L1). For example, L0 is 250 mm or more and 300 mm or less, and L1 is 80 mm or more and 90 mm or less. The thickness of the electrode body 200 (the dimension in the Y direction) is 20 mm or more and 40 mm or less. In addition, the dimension ratio (L0 / L1) in the X direction to the Z direction is, for example, 1.5 or more, 2 or more, or 3 or more. L0 / L1 is, for example, 30 or less, 10 or less, or 5 or less. However, the dimensions of the electrode body 200 are not limited to the above ranges.

[0102] like Figure 21As shown, the first portion 610 is preferably formed in a region extending in a strip along the X direction to overlap with the electrode body 200. The Z-direction dimension (L2) of the region where the flat portion of the electrode body 200 overlaps with the first portion 610 is preferably at least 1 / 10 of the Z-direction dimension (L1) of the electrode body 200, more preferably at least 1 / 8. L2 is preferably at least 1 / 4 of L1. However, the relationship between L1 and L2 is not limited to the above ranges.

[0103] like Figure 22 As shown, the electrode body 200 preferably has a small gap between itself and the inner surface of the housing body 110 in the Z direction. Figure 22 In this design, the vertical gaps are assumed to be equal. Here, the dimension (L4) in the Z direction from the inner surface of the housing body 110 to the end (center side in the Z direction) of the first portion 610 is preferably at least 1 / 10 of the dimension (L3) in the Z direction of the internal space of the housing body 110, more preferably at least 1 / 8. L4 is preferably less than 1 / 4 of L3. However, the relationship between L3 and L4 is not limited to the above range.

[0104] exist Figure 21 , Figure 22 In this example, for ease of illustration, the electrode body 200 and the spacer 600 are made to be the same size, but the spacer 600 can also be formed to be shorter or longer than the electrode body 200 in the X or Z direction. Figure 21 , Figure 22 The diagram only shows the area in the first part 610 that overlaps with the electrode body 200 (flat surface 2000).

[0105] When a battery pack is constructed by constraining a square-shaped housing 100 in the Y direction, the pressure load tends to be relatively small, especially near the first end edge 101. If a deviation in the pressure load causes a deviation in the potential within the positive electrode plate 220 of the electrode body 200, metal deposition (lithium deposition in lithium-ion batteries) may occur.

[0106] In contrast, in the secondary battery 1 of this embodiment, by relatively increasing the thickness of the spacer 600 at the first portions 610 located at both ends in the Z direction, the reduction in pressure load near the first end edge 101 of the housing body 110 can be suppressed. Therefore, lithium deposition (metal deposition) can be effectively suppressed in the portion where the pressure load tends to be relatively small.

[0107] Embodiments of the invention have been described, but the embodiments disclosed herein should be considered illustrative rather than limiting in all respects. The scope of the invention is set forth in the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A secondary battery, wherein, The secondary battery has the following features: An electrode body having a pair of main surfaces; A spacer having a flat surface facing one of the pair of main surfaces; and An outer container, having a square shape, houses the electrode body and the spacer. The outer can has a pair of first faces facing the pair of main faces, a pair of second faces approximately orthogonal to the first faces, and a pair of third faces approximately orthogonal to the first and second faces, wherein the area of ​​the first faces is larger than the area of ​​the second faces and the area of ​​the third faces. The first surface has a generally rectangular shape including a pair of first end edges extending along a first direction and a pair of second end edges extending along a second direction substantially orthogonal to the first direction, wherein the pair of first end edges is longer than the pair of second end edges. The spacer has a pair of first portions located at both ends in the second direction and a second portion located between the pair of first portions in the second direction. The flat surface of the spacer is formed continuously from one of the pair of first portions to the other. At least a portion of the first portion in the first direction has a greater thickness than the second portion in a direction orthogonal to the flat surface.

2. The secondary battery as described in claim 1, wherein, The thickness of the first portion in at least its central portion in the first direction, in a direction orthogonal to the flat surface, is greater than that of the second portion.

3. The secondary battery as described in claim 1 or 2, wherein, The thickness of the first portion in the entire region of the first direction, in the direction orthogonal to the flat surface, is greater than that of the second portion.

4. The secondary battery as described in claim 1 or 2, wherein, The spacer extends to the outside of the electrode body in the second direction.

5. The secondary battery as described in claim 1 or 2, wherein, The secondary battery also includes an insulating component disposed on the outside of the electrode body.

6. A battery pack, wherein, The battery pack includes: A plurality of secondary batteries, wherein the plurality of secondary batteries are the secondary batteries as described in claim 1 or 2, are arranged in a third direction orthogonal to the first direction and the second direction; as well as A battery spacer is disposed between the plurality of secondary batteries. When viewed from the third-party perspective, the area of ​​the battery spacer is smaller than the area of ​​the first surface of the outer can.

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