Square battery

Abstract

Provided is a square battery in which pressure is less likely to concentrate on a joint part of a case. According to the present invention, a square battery provided with a laminated electrode body having a positive electrode plate and a negative electrode plate can be provided. The negative electrode plate has a negative electrode active material layer containing an Si-containing material. The negative electrode active material layer has a sealing plate-side region provided at an end portion on the sealing plate side, and a central region provided in a belt shape at a central portion in the first direction. The sealing plate side region does not contain the Si-containing material, or the content of the Si-containing material is lower than that of the central region.

Description

Technical Field

[0001] This invention relates to prismatic batteries. Background Technology

[0002] Previously known energy storage devices include: a housing having a housing body with an opening and a sealing plate for sealing the opening; and an electrode body housed inside the housing (see, for example, Japanese Patent Application Publication No. 2006-040684 and International Publication No. 2021 / 261358).

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-040684

[0006] Patent Document 2: International Publication No. 2021 / 261358 Summary of the Invention

[0007] For example, as described in Japanese Patent Application Publication No. 2006-040684, the electrode body may expand due to repeated charging and discharging. In this case, for a prismatic battery with a square casing, the pressure applied to the casing tends to become uneven, with relatively high pressure tending to be applied to the larger surface area. Therefore, compared to cylindrical or laminated batteries, prismatic batteries are more prone to casing deformation or breakage.

[0008] Furthermore, according to the inventors of this application, in recent years, from the viewpoint of increasing energy density, the shape of the electrode body has become approximately the same as the internal dimensions of the casing. In particular, laminated electrodes, unlike wound electrodes, do not have curved portions (R-corners), and therefore, when they expand due to repeated charging and discharging, they tend to strongly compress the corners of the casing. This expansion is especially pronounced when the negative electrode plate contains Si-containing materials from the viewpoint of increasing capacity. Consequently, there is a problem that pressure tends to concentrate at the joint between the casing body and the sealing plate.

[0009] The present invention was made in view of the above circumstances, and its main objective is to provide a square battery in which pressure is difficult to concentrate at the joint of the casing.

[0010] According to the present invention, a prismatic battery is provided, comprising a prismatic casing and a laminated electrode body. The casing includes: a casing body having a first surface of a generally rectangular shape including a pair of long sides and a pair of short sides; a pair of second surfaces extending from the pair of long sides and having an area larger than the first surface; and one or more openings; and one or more sealing plates sealing the one or more openings. The laminated electrode body is housed inside the casing and has a positive electrode plate and a negative electrode plate arranged generally parallel to the second surfaces. The negative electrode plate includes a negative electrode active material layer comprising a Si-containing material as the negative electrode active material. The negative electrode active material layer has: one or more sealing plate side regions provided in a strip shape at the ends of the one or more sealing plate sides; and a central region provided in a strip shape at the center of a first direction orthogonal to the sealing plate. The sealing plate side regions do not contain the Si-containing material, or the content of the Si-containing material in the sealing plate side regions is lower than that in the central region.

[0011] In this invention, the sealing plate side region of the negative electrode plate does not contain Si-containing material, or has a lower Si-containing material content compared to the central region. This suppresses pressure concentration at the junction of the housing body and the sealing plate. Furthermore, it suppresses breakage at the junction. Additionally, by relatively increasing the Si-containing material content in the central region of the negative electrode plate, the energy density can be improved. Attached Figure Description

[0012] Figure 1 This is a schematic perspective view of a square battery 100 according to one embodiment.

[0013] Figure 2 It is along Figure 1 A schematic longitudinal section view of line II-II.

[0014] Figure 3 This is a schematic top view of the negative electrode plate.

[0015] Figure 4 The variations involve the same principles as those in the example. Figure 1 A fairly accurate diagram.

[0016] Figure 5 It is along Figure 4 A schematic longitudinal sectional view of the V-V line.

[0017] Figure 6 The variations involve the same principles as those in the example. Figure 3 A fairly accurate diagram. Detailed Implementation

[0018] Hereinafter, preferred embodiments of the technology disclosed herein will be described with appropriate reference to the accompanying drawings. Furthermore, matters other than those specifically mentioned in this specification that are essential for implementing the technology disclosed herein (e.g., the general structure and manufacturing process of a square battery that does not constitute a feature of the technology disclosed herein) can be understood as design matters by those skilled in the art based on prior art. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the art. Additionally, the expression "A to B" indicating scope in this specification includes meanings of A and below, and "preferably greater than A" and "preferably less than B".

[0019] Figure 1 This is a 3D diagram of a square battery (model 100). Figure 2 It is along Figure 1 A schematic longitudinal sectional view along line II-II. Furthermore, in the following description, components and parts that perform the same function will be labeled with the same reference numerals, and repeated descriptions will be omitted or simplified. Additionally, the symbols F, Rr, L, R, U, and D in the drawings represent front, back, left, right, top, and bottom, respectively; and the symbols X, Y, and Z represent the short side direction (thickness direction), the long side direction orthogonal to the short side direction, and the up / down direction orthogonal to both the short and long side directions, respectively. The up / down direction Z is typically the direction aligned with the vertical direction. However, these are merely for ease of explanation and do not impose any limitations on the arrangement of the square battery 100.

[0020] like Figure 2 As shown, the prismatic battery 100 includes a prismatic casing 10, a laminated electrode body 20, a positive terminal 30, and a negative terminal 40. Although not shown in the figure, the prismatic battery 100 also includes an electrolyte. The prismatic battery 100 is a secondary battery in this context. Specifically, it is a non-aqueous electrolyte secondary battery. The prismatic battery 100 is preferably a lithium-ion secondary battery. Furthermore, in this specification, "secondary battery" is a general term referring to an energy storage device that can be repeatedly charged and discharged, and includes the concepts of secondary batteries such as lithium-ion secondary batteries or nickel-metal hydride batteries, and capacitors that utilize chemical reactions, such as lithium-ion capacitors or pseudocapacitors.

[0021] The housing 10 is a frame that houses the laminated electrode body 20 and the electrolyte. For example... Figure 1 As shown, the housing 10 has a flat, bottomed cuboid shape (square). The housing 10 has a size corresponding to the size of the laminated electrode body 20. The material of the housing 10 can be the same as conventionally used materials, without particular limitation. The housing 10 is preferably made of metal, and more preferably of aluminum, aluminum alloy, iron, iron alloy, etc.

[0022] like Figure 2As shown, in this embodiment, the housing 10 includes: a bottomed square (box-shaped) housing body 12 having an opening 12h on one side (here, the upper side); and a sealing plate (cover) 14 that seals the opening 12h of the housing body 12. Here, there is one opening 12h and one sealing plate 14 on the housing body 12. The housing 10 is integrated by joining the sealing plate 14 to the periphery of the opening 12h of the housing body 12. In this embodiment, integration is achieved by welding the seam between the housing body 12 and the sealing plate 14, for example, by laser welding. Specifically, at the periphery of the opening 12h of the housing body 12, on the long side 12b (second side, see below) of the housing body 12 (described later). Figure 1 The short side 12c and the boundary between the sealing plate 14 form a joint (specifically, a welded joint WP). The housing 10 is hermetically sealed (closed).

[0023] like Figure 1 As shown, the main body 12 of the casing includes: a generally rectangular bottom surface 12a having a pair of long sides and a pair of short sides; a pair of long side surfaces 12b extending from the pair of long sides of the bottom surface 12a and facing each other; and a pair of short side surfaces 12c extending from the pair of short sides of the bottom surface 12a and facing each other. The bottom surface 12a faces the sealing plate 14. The bottom surface 12a is an example of a "first surface". The long side surfaces 12b are the surfaces with the largest area. That is, the area of ​​the long side surfaces 12b is larger than that of the bottom surface 12a. The area of ​​the long side surfaces 12b is larger than that of the short side surfaces 12c. The long side surfaces 12b are an example of a "second surface".

[0024] Furthermore, in this specification, the term "generally rectangular" means, in addition to a complete rectangle, it also includes, for example, a shape in which the corners connecting the long and short sides of a rectangle are R-shaped, or a shape with notches at the corners, etc.

[0025] The sealing plate 14 is a plate-shaped member that blocks the opening 12h of the housing body 12. Here, the sealing plate 14 faces the bottom surface 12a (first surface) of the housing body 12. The sealing plate 14 is approximately rectangular. Figure 2 As shown, the sealing plate 14 is provided with an injection hole 15, an vent valve 17, and two terminal outlet holes 18 and 19. The injection hole 15 is a through hole for injecting electrolyte into the interior of the housing 10 after the sealing plate 14 is assembled to the housing body 12. The injection hole 15 is sealed by the sealing member 16 after the electrolyte is injected. The vent valve 17 is configured to rupture when the pressure inside the housing 10 reaches a specified value or higher, allowing the pressure inside the housing 10 to escape to the outside. The terminal outlet holes 18 and 19 are respectively formed at both ends in the long side direction Y of the sealing plate 14. The terminal outlet holes 18 and 19 penetrate the sealing plate 14 in the vertical direction Z.

[0026] The positive terminal 30 is disposed at one end of the sealing plate 14 on the side in the Y direction along its long side. Figure 1 , Figure 2 (The left end). For example, Figure 2 As shown, the positive terminal 30 is inserted through the terminal lead-out hole 18 and extends from the inside to the outside of the sealing plate 14. Here, the positive terminal 30 is riveted and fixed to the periphery of the sealing plate 14 surrounding the terminal lead-out hole 18 by riveting. At the end of the positive terminal 30 on the housing body 12 side ( Figure 2 The lower end of the electrode has a riveting portion 30c. The positive terminal 30 is electrically connected to the positive electrode plate 22 of the laminated electrode body 20 inside the housing 10 via the positive current collector 50 and the positive electrode tab 22t described later. The positive terminal 30 is preferably made of metal, more preferably of, for example, aluminum or an aluminum alloy. The positive terminal 30 is insulated from the sealing plate 14 by a gasket 92 and an internal insulating member 94.

[0027] The negative terminal 40 is located at the end of the sealing plate 14 on the other side in the Y direction (long side). Figure 1 , Figure 2 (The right end). For example Figure 2 As shown, the negative terminal 40 is inserted through the terminal lead-out hole 19 and extends from the inside to the outside of the sealing plate 14. Here, the negative terminal 40 is riveted and fixed to the periphery of the sealing plate 14 surrounding the terminal lead-out hole 19 by riveting. At the end of the negative terminal 40 on the housing body 12 side ( Figure 2 The lower end of the electrode has a riveting portion 40c. The negative terminal 40 is electrically connected to the negative electrode plate 24 of the laminated electrode body 20 inside the housing 10 via the negative current collector 60 and the negative electrode tab 24t (described later). The negative terminal 40 is preferably made of metal, and more preferably, for example, copper or a copper alloy. The negative terminal 40 is insulated from the sealing plate 14 by a gasket 92 and an internal insulating member 94.

[0028] The electrolyte is contained inside the housing 10. The electrolyte can be the same as conventional electrolytes, without particular limitation. Typically, the electrolyte is a non-aqueous electrolyte containing a non-aqueous solvent and a supporting salt (electrolyte salt). However, in other embodiments, the electrolyte can also be an aqueous electrolyte containing an aqueous solvent. Examples of non-aqueous solvents include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorinated lithium salts such as lithium hexafluorophosphate (LiPF6). The electrolyte may also contain additives as needed. Furthermore, in other embodiments, the electrolyte can also be solid (solid electrolyte) and integrated with the laminated electrode body 20.

[0029] like Figure 2As shown, the laminated electrode 20 is housed inside the housing 10. Here, the laminated electrode 20 is housed inside the housing 10 covered by a resin insulating sheet (electrode support) 29. Having a positive electrode tab 22t and a negative electrode tab 24t, the laminated electrode 20 is disposed opposite each other on the lower side (bottom surface 12a (first surface) side) within the housing 10. In other words, the gap d1 between the bottom surface 12a (first surface) and the lower end of the laminated electrode 20 is smaller than the gap d3 between the sealing plate 14 and the upper end of the laminated electrode 20 (i.e., d1 < d3).

[0030] The laminated electrode body 20 has a positive electrode plate 22 and a negative electrode plate 24 arranged (laminated) substantially parallel to the long side surface 12b (second side) of the housing 10. The laminated electrode body 20 typically has multiple positive electrode plates 22 and multiple negative electrode plates 24. Here, the positive electrode plate 22 and the negative electrode plate 24 are square (specifically rectangular). The positive electrode plate 22 and the negative electrode plate 24 are arranged such that their long sides are along the long side direction Y and their short sides are along the vertical direction Z. The positive electrode plate 22 and the negative electrode plate 24 face each other in the short side direction X (lamination direction) in an insulated state separated by a separator (not shown) or the like.

[0031] Furthermore, the term "approximately parallel" in this specification is not parallel in the strict sense, but rather a wording that allows for a few degrees of inclination. For example, it means that the angle between the direction of the long side 12b (the second side) and the direction of the positive electrode plate 22 or the negative electrode plate 24 is 10° or less (preferably 5° or less).

[0032] The positive electrode plate 22 has: a positive electrode tab 22t protruding towards the sealing plate 14; and a positive electrode active material layer 22a. The positive electrode tab 22t protrudes upward from the laminated electrode body 20. Here, the positive electrode tab 22t is part of the positive electrode current collector. Specifically, the positive electrode tab 22t is a convex portion of the positive electrode current collector exposed where the positive electrode active material layer 22a is not formed. Here, the positive electrode tab 22t is electrically connected to the positive terminal 30 via the positive electrode current collector member 50. The positive electrode tab 22t (positive electrode current collector) is preferably made of metal foil, and particularly preferably of aluminum foil or aluminum alloy foil. However, in other embodiments, the positive electrode tab 22t may also be a component separately disposed from the positive electrode plate 22.

[0033] The positive electrode active material layer 22a is fixed on at least one (preferably both) face of the positive electrode current collector in the short-side direction X. The composition of the positive electrode active material layer 22a can be the same as conventionally used and is not particularly limited. The positive electrode active material layer 22a contains a positive electrode active material capable of reversibly adsorbing and discharging charge carriers. As the positive electrode active material, a lithium transition metal composite oxide is preferred; for example, a lithium nickel cobalt manganese composite oxide can be cited. The positive electrode active material layer 22a may also contain any components other than the positive electrode active material, such as conductive materials, positive electrode binders, various additives, etc. As a conductive material, carbon materials such as acetylene black (AB) are preferred, for example. As a positive electrode binder, polyvinylidene fluoride (PVdF) is preferred, for example.

[0034] The negative electrode plate 24 has: a negative electrode tab 24t protruding towards the sealing plate 14; and a negative electrode active material layer 24a. The negative electrode tab 24t protrudes upward from the laminated electrode body 20. Here, the negative electrode tab 24t is part of the negative electrode current collector. Specifically, the negative electrode tab 24t is a convex portion of the negative electrode current collector exposed where the negative electrode active material layer 24a is not formed. Here, the negative electrode tab 24t is electrically connected to the negative terminal 40 via the negative electrode current collector member 60. The negative electrode tab 24t (negative electrode current collector) is preferably made of metal foil, particularly preferably of copper foil or copper alloy foil. However, in other embodiments, the negative electrode tab 24t may also be a component separately disposed from the negative electrode plate 24.

[0035] The negative electrode active material layer 24a is fixed on at least one (preferably both) face of the negative electrode current collector in the short-side direction X. The composition of the negative electrode active material layer 24a can be the same as before and is not particularly limited. The negative electrode active material layer 24a contains a negative electrode active material capable of reversibly adsorbing and discharging charge carriers. The negative electrode active material layer 24a contains at least a Si-containing material as the negative electrode active material. The Si-containing material can be Si, or silicon-containing compounds such as silicon oxide, silicon carbide, and silicon nitride. The negative electrode active material layer 24a preferably also contains a carbon material such as graphite as the negative electrode active material. The graphite can be natural graphite, artificial graphite, or amorphous carbon-coated graphite in the form of graphite particles as a core coated with amorphous carbon material.

[0036] The negative electrode active material layer 24a may also contain any components other than the negative electrode active material, such as a negative electrode binder, a conductive material, and various additives. As a negative electrode binder, rubbers such as styrene-butadiene rubber (SBR) and cellulose-based materials such as carboxymethyl cellulose (CMC) are preferred. As a conductive material, carbon materials are preferred.

[0037] Figure 3 This is a schematic top view of the negative electrode plate 24. (See attached image.) Figure 3As shown, the negative electrode active material layer 24a has multiple portions with different compositions in the vertical direction Z. The vertical direction Z is an example of a "first direction orthogonal to the sealing plate". In this embodiment, the negative electrode active material layer 24a is divided into three regions in the vertical direction Z: a ​​sealing plate side region A3, a central region A2, and a bottom side region A1. However, in other embodiments, the negative electrode active material layer 24a (electrode active material layer) may have other regions (a fourth or fifth region) such as between the bottom side region A1 and the central region A2, or between the sealing plate side region A3 and the central region A2. The sealing plate side region A3 is a region that is provided in a strip shape at the end (upper end) of the sealing plate 14. The central region A2 is a region that is provided in a strip shape at the center of the vertical direction Z. The central region A2 includes the center of the negative electrode active material layer 24a in the vertical direction Z (first direction). Here, the central region A2 is the region located between the bottom side region A1 and the sealing plate side region A3. The bottom side region A1 is a strip-shaped region located at the end (lower end) of the bottom surface 12a (first surface). The bottom side region A1 can be any region, such as as described in the variant examples below, or it may not be provided. The bottom side region A1 is an example of the "first surface side region".

[0038] In some embodiments, it is preferred that the properties (e.g., density or thickness) of each region (here, the sealing plate side region A3, the central region A2, and the bottom side region A1) of the negative electrode active material layer 24a are identical. Furthermore, in this specification, "density" refers to the solid weight per unit volume (g / cm³) of the negative electrode active material layer 24a. 3 The density can be obtained by dividing the mass of the negative electrode active material layer 24a by the apparent volume of the negative electrode active material layer 24a.

[0039] In this embodiment, the sealing plate side region A3 does not contain Si-containing material, or the content of Si-containing material (the proportion of Si-containing material) is lower than that of the central region A2. The laminated electrode body 20 expands in the short side direction X (lamination direction) due to repeated charging and discharging. According to the inventors of this application, the higher the content of Si-containing material, the greater the expansion of the laminated electrode body 20. Therefore, in the technology disclosed herein, the content of Si-containing material in the sealing plate side region A3 of the negative electrode plate 24 is relatively reduced. As a result, pressure concentration at the weld joint WP between the housing body 12 and the sealing plate 14 of the housing 10 can be suppressed. Furthermore, damage to the weld joint WP of the housing 10 can be suppressed. In addition, by relatively increasing the content of Si-containing material in the central region A2 of the negative electrode plate 24, the weight per unit area of ​​each cell of the prismatic battery 100 can be relatively increased, thereby improving the energy density.

[0040] In some embodiments, the bottom side region A1 (first side region) does not contain Si-containing material, or the content of Si-containing material is lower than that in the central region A2. This suppresses pressure concentration at the boundary (lower corner) between the long side surface 12b (second side) and the bottom surface 12a (first side) of the housing 10. Furthermore, it better suppresses deformation or breakage of the housing 10.

[0041] In this embodiment, it is preferable that the negative electrode active material layer 24a further comprises graphite as the negative electrode active material, and the graphite content in the sealing plate side region A3 is higher than that in the central region A2. Furthermore, it is preferable that the graphite content in the bottom side region A1 is higher than that in the central region A2. This mitigates the differences in charge-discharge reactions in each region of the negative electrode active material layer 24a.

[0042] The sealing plate side region A3 may or may not contain Si-containing materials. The negative electrode active material in the sealing plate side region A3 may be configured to contain Si-containing materials and graphite, or it may consist only of graphite. From the viewpoint of high capacity, the sealing plate side region A3 is more preferably composed of Si-containing materials, and even more preferably, it contains both Si-containing materials and graphite. While not particularly limited, the content of Si-containing materials in the total negative electrode active material in the sealing plate side region A3 is preferably less than 20% by mass, more preferably 1 to 18% by mass, and even more preferably 5 to 15% by mass. By setting the content of Si-containing materials to a predetermined value or below, pressure concentration is less likely to occur at the weld joint WP of the casing 10, thus maximizing the effectiveness of the disclosed technology. Furthermore, by setting the content of Si-containing materials to a predetermined value or above, high energy density of the prismatic battery 100 can be achieved.

[0043] Furthermore, in the sealing plate side region A3, the content of graphite in the overall negative electrode active material is preferably greater than that of Si-containing materials, more preferably 50% by mass or more, and even more preferably 80 to 100% by mass, particularly preferably 85 to 95% by mass.

[0044] The central region A2 contains Si-containing material as an essential component. The negative electrode active material in the central region A2 can be composed of Si-containing material and graphite, or it can be composed of only Si-containing material. Although not particularly limited, the content of Si-containing material in the central region A2 is preferably 20% by mass or more, more preferably 20 to 60% by mass, for example, 50% by mass or less, and even more preferably 20 to 30% by mass. By setting the content of Si-containing material to a predetermined value or more, high energy density of the prismatic battery 100 can be achieved. In addition, by setting the content of Si-containing material to a predetermined value or more, strong pressure is less likely to be applied to the long side 12b (second side) of the casing 10, which can better suppress deformation or breakage of the casing 10 and maximize the effect of the technology disclosed herein.

[0045] Furthermore, in the central region A2, the overall content of graphite in the negative electrode active material is preferably higher than that of Si-containing materials, more preferably 40% by mass or more, and even more preferably 40 to 80% by mass, for example 50% by mass or more, and particularly preferably 70 to 80% by mass.

[0046] The bottom side region A1 may or may not contain Si-containing materials. The negative electrode active material in the bottom side region A1 may be composed of Si-containing materials and graphite, or only graphite. From the viewpoint of high capacity, it is preferable that the bottom side region A1 contains Si-containing materials, and more preferably, it contains both Si-containing materials and graphite. The content of Si-containing materials in the bottom side region A1 may be the same as or different from that in the sealing plate side region A3. Although not particularly limited, the content of Si-containing materials in the bottom side region A1 is preferably less than 20% by mass, more preferably 1 to 18% by mass, and even more preferably 5 to 15% by mass. By setting the content of Si-containing materials to a predetermined value or less, pressure concentration is less likely to occur at the weld joint WP of the casing 10, thus maximizing the effectiveness of the disclosed technology. Furthermore, by setting the content of Si-containing materials to a predetermined value or more, high energy density of the prismatic battery 100 can be achieved.

[0047] Furthermore, in the bottom side region A1, the content of graphite in the overall negative electrode active material is preferably greater than that of Si-containing materials, more preferably 50% by mass or more, and even more preferably 80 to 100% by mass, particularly preferably 85 to 95% by mass.

[0048] Furthermore, in each region of the negative electrode active material layer 24a (here, the sealing plate side region A3, the central region A2, and the bottom side region A1), the proportion of the negative electrode active material is preferably 95% by mass or more, more preferably 98% by mass or more. In this case, the content of the Si-containing material in the "total negative electrode active material" is approximately equal to its content in each region. Therefore, in some embodiments, in the sealing plate side region A3, the content of the Si-containing material in the entire sealing plate side region A3 is preferably less than 20% by mass, more preferably 1 to 18% by mass, and even more preferably 5 to 15% by mass. In the central region A2, the content of the Si-containing material in the entire central region A2 is preferably 20% by mass or more, more preferably 20 to 60% by mass, and even more preferably 20 to 30% by mass. In the bottom side region A1, the content of the Si-containing material in the entire bottom side region A1 is preferably less than 20% by mass, more preferably 1 to 18% by mass, and even more preferably 5 to 15% by mass.

[0049] While there are no specific limitations, the preferred option is, for example... Figure 3 As shown, in the vertical direction Z (first direction), when the overall width Wa of the negative electrode active material layer 24a is set to 100%, the proportions W3 (%) of the width of the sealing plate side region A3 and the proportions W1 (%) of the width of the bottom side region A1 are smaller than the proportions W2 (%) of the width of the central region A2 (i.e., W3 < W2 and W1 < W2). By suppressing the proportions W3 and W1 of the widths of the sealing plate side region A3 and the bottom side region A1, which have relatively low Si material content, high energy density of the prismatic battery 100 can be achieved.

[0050] The width ratio W3 of the sealing plate side region A3 and the width ratio W1 of the bottom side region A1 can be the same or different. While not particularly limited, it is preferable that the width ratio W3 of the sealing plate side region A3 and the width ratio W1 of the bottom side region A1 are both 5% or more, more preferably 10% or more. This makes it difficult for pressure to concentrate at the corners of the long side surface 12b (second side) of the housing 10, thus better suppressing deformation or damage to the housing 10. The width ratio W3 of the sealing plate side region A3 is more preferably 15-30%. The width ratio W1 of the bottom side region A1 is more preferably 10-30%. By setting the width ratios W3 and W1 of the sealing plate side region A3 and the bottom side region A1 to predetermined values ​​or below, high energy density of the prismatic battery 100 can be achieved.

[0051] When the negative electrode active material layer 24a is divided into three regions as in this embodiment, the width ratio W2 of the central region A2 can be calculated using the following formula: 100 - (W1 + W3). The width ratio W2 of the central region A2 is preferably larger than the width ratio W1 of the bottom side region A1 and the width ratio W3 of the sealing plate side region A3, preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more, for example, preferably 40-80%, and particularly preferably 40-75%. By setting the width ratio W2 of the central region A2 to a predetermined value or higher, high energy density of the prismatic battery 100 can be achieved.

[0052] In some embodiments, when the laminated electrode body 20 is disposed opposite to the bottom surface 12a (first surface) side in the vertical direction Z (first direction), it is preferable that the width ratio W1 of the bottom surface side region A1 is greater than the width ratio W3 of the sealing plate side region A3 (i.e., W3 < W1). This makes it less likely for pressure to concentrate at the corners near the bottom surface 12a (first surface) side of the laminated electrode body 20, thus better suppressing deformation or breakage of the housing 10. More preferably, the width ratios W1 to W3 of the negative electrode active material layer 24a satisfy W3 < W1 < W2. This allows for the simultaneous achievement of the effects of the technology disclosed herein and high energy density at a higher level.

[0053] The square battery 100 can be used for various purposes, such as serving as a power source (drive power source) for motors in passenger cars, trucks, and other vehicles. There are no particular limitations on the type of vehicle; examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0054] The preferred embodiments of the present invention have been described above, but these embodiments are merely examples. The present invention can be implemented in various other ways. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field. The technology described in the claims includes configurations obtained by various modifications and alterations to the embodiments illustrated above. For example, a portion of the above embodiments can be replaced with other modifications, and other modifications can be added to the above embodiments. Furthermore, if a technical feature is not described as an essential component, it can be appropriately omitted.

[0055] For example, in the above Figure 1 , Figure 2In this embodiment, the shell body 12 has one opening 12h and one sealing plate 14. However, it is not limited to this. Figure 4 The variations involve the same principles as those in the example. Figure 1 A fairly accurate diagram. Figure 5 It is along Figure 4 A schematic longitudinal sectional view of the V-V line.

[0056] Figure 4 , Figure 5 The square battery 200 shown has a square casing 110, a laminated electrode body 120, a positive terminal 130, and a negative terminal 140. For example... Figure 5 As shown, the housing 110 includes: a cylindrical housing body 112 having a pair (2) openings 112h at both ends in the long side direction Y; and two sealing plates 114 that block the pair of openings 112h of the housing body 112. That is, in this modified example, the housing body 112 has two openings 112h and two sealing plates 114.

[0057] like Figure 4 As shown, the housing body 112 includes: a generally rectangular bottom surface 112a (first surface) having a pair of long sides and a pair of short sides; a pair of long side surfaces 112b (second surfaces) extending from the pair of long sides of the bottom surface 112a and facing each other; and a top surface 112c facing the bottom surface 112a. The housing body 112 is formed, for example, by bending a metal sheet into a square tube shape and joining the seams (e.g., by welding). Two sealing plates 114 are arranged facing each other in a manner orthogonal to the bottom surface 112a (first surface) and the long side surfaces 112b (second surface).

[0058] Positive extreme 130 is set in the first ( Figure 4 , Figure 5 The sealing plate 114 on the right side, and the negative terminal 140 are set in the second ( Figure 4 , Figure 5 (Left side) Sealing plate 114. Additionally, the electrolyte injection hole 115, together with the positive terminal 130, is located on the first sealing plate 114. The electrolyte injection hole 115 is sealed by a sealing plug 116.

[0059] The laminated electrode 120 is housed inside the housing 110 and has a positive electrode 122 and a negative electrode 124 arranged substantially parallel to the long side surface 112b (second side). The positive electrode 122 (positive electrode tab 122t) is electrically connected to the positive terminal 130 via a positive current collector 150. The negative electrode 124 (negative electrode tab 124t) is electrically connected to the negative terminal 140 via a negative current collector 160.

[0060] Figure 6 The variations involve the same principles as those in the example. Figure 3The corresponding diagram is a schematic top view of the negative electrode plate 124. In this modified example, the long side direction Y is the "first direction orthogonal to the sealing plate." Figure 6 As shown, the negative electrode active material layer 124a of the negative electrode plate 124 is divided into a sealing plate side region A3 and a central region A2. In the negative electrode plate 124, the sealing plate side region A3 is respectively located in the first ( Figure 4 , Figure 5 The end of the sealing plate 114 on the right side and the second ( Figure 4 , Figure 5 The end of the sealing plate 114 on the left side. Here, the central region A2 is the region including the center of the long side direction Y (first direction) of the negative electrode active material layer 124a, and more preferably it is arranged symmetrically about the center of the long side direction Y.

[0061] Furthermore, for the sealing plate side region A3 and the central region A2, the width ratios W3 and W2 relative to the overall width Wa in the long side direction Y (first direction) can be the same as in the above-described embodiment. For example, in the long side direction Y (first direction), when the overall width Wa of the negative electrode active material layer 124a is set to 100%, it is preferable that the width ratios W3 (%) of the two sealing plate side regions A3 are each smaller than the width ratio W2 (%) of the central region A2. More preferably, the width ratios W3 of the two sealing plate side regions A3 are each 10% or more.

[0062] As described above, the following components can be listed as specific examples of the technology disclosed herein.

[0063] Item 1: A square battery, wherein the square battery comprises a square casing and a laminated electrode body, the casing comprising: a casing body having a first surface of a generally rectangular shape including a pair of long sides and a pair of short sides, a pair of second surfaces extending from the pair of long sides and having an area larger than the first surface, and one or more openings; and one or more sealing plates sealing the one or more openings, the laminated electrode body being housed inside the casing and having a positive electrode plate and a negative electrode plate arranged generally parallel to the second surface, the negative electrode plate having a negative electrode active material layer comprising a Si-containing material as a negative electrode active material, the negative electrode active material layer having: one or more sealing plate side regions provided in a strip shape at the ends of the one or more sealing plate sides; and a central region provided in a strip shape at the center of a first direction orthogonal to the sealing plate, the sealing plate side regions not containing the Si-containing material, or the content of the Si-containing material in the sealing plate side regions being lower than that in the central region.

[0064] Item 2: The square battery as described in Item 1, wherein the negative electrode active material layer further comprises graphite as the negative electrode active material, and the graphite content in the sealing plate side region is higher than that in the central region.

[0065] Item 3: The square battery as described in Item 1 or 2, wherein in the sealing plate side region, the Si-containing material accounts for less than 20% by mass of the total negative electrode active material, and in the central region, the Si-containing material accounts for more than 20% by mass of the total negative electrode active material.

[0066] Item 4: The square battery as described in any one of items 1 to 3, wherein the opening and the sealing plate of the casing body are each one, the sealing plate faces the first surface, and the negative electrode active material layer further has a first surface side region provided in a strip shape at the end of the first surface side, the first surface side region does not contain the Si-containing material, or the content of the Si-containing material in the first surface side region is lower than that in the central region.

[0067] Item 5: The square battery as described in Item 4, wherein, in the first direction, when the overall width of the negative electrode active material layer is set to 100%, the proportion of the width of the sealing plate side region and the proportion of the width of the first surface side region are respectively less than the proportion of the width of the central region.

[0068] Item 6: The square battery as described in Item 4 or 5, wherein the ratio of the width of the two sealing plate side regions is 10% or more respectively.

[0069] Item 7: The square battery as described in any one of items 4 to 6, wherein the laminated electrode is disposed closer to the first surface than the sealing plate in the first direction, and the proportion of the width of the first surface side region is greater than the proportion of the width of the sealing plate side region.

[0070] Item 8: The square battery as described in any one of Items 1 to 3, wherein the opening and the sealing plate of the casing body are two in number, the two sealing plates are arranged facing each other in a manner orthogonal to the first surface and the second surface, and the sealing plate side regions are respectively provided at the end of the first sealing plate side and the end of the second sealing plate side.

[0071] Item 9: The square battery as described in Item 7, wherein, in the first direction, when the overall width of the negative electrode active material layer is set to 100%, the width ratio of the two sealing plate side regions is less than the width ratio of the central region.

[0072] Item 10: A square battery as described in Item 7 or 8, wherein the ratio of the width of the two sealing plate side regions is 10% or more respectively.

[0073] Explanation of reference numerals in the attached figures

[0074] 10, 110 housing

[0075] 12a, 112a bottom surface (side 1)

[0076] Long side view (second side) of 12b and 112b

[0077] 14, 114 sealing board

[0078] 20 and 120 layered electrode bodies

[0079] 22, 122 positive electrode plates

[0080] 24, 124 negative electrode plates

[0081] 24a, 124a negative electrode active material layers

[0082] 24t, 124t negative electrode tabs

[0083] 100 and 200 square batteries

[0084] Z (up / down direction) (first direction in the implementation method)

[0085] Y-direction (the first direction in the variant example)

Claims

1. A prismatic battery, wherein the prismatic battery has a prismatic case and a laminated electrode body, the case has: a case main body having a first surface of a substantially rectangular shape including a pair of long sides and a pair of short sides, a pair of second surfaces each extending from the pair of long sides and having a larger area than the first surface, and one or a plurality of openings; and one or a plurality of sealing plates sealing the one or a plurality of openings, the laminated electrode body is housed inside the case and has a positive electrode plate and a negative electrode plate disposed substantially parallel to the second surfaces, the negative electrode plate has a negative electrode active material layer containing a Si-containing material as a negative electrode active material, the negative electrode active material layer has: one or a plurality of sealing plate side regions provided in end portions of the one or a plurality of sealing plates in a strip shape; and a central region provided in a central portion in a first direction orthogonal to the sealing plates in a strip shape, the sealing plate side regions do not contain the Si-containing material, or the Si-containing material is contained at a lower rate in the sealing plate side regions than in the central region.

2. The prismatic battery according to claim 1, wherein the negative electrode active material layer further contains graphite as the negative electrode active material, the rate of the graphite is higher in the sealing plate side regions than in the central region.

3. The prismatic battery according to claim 2, wherein in the sealing plate side regions, the proportion of the Si-containing material to the entire negative electrode active material is less than 20 mass%, in the central region, the proportion of the Si-containing material to the entire negative electrode active material is 20 mass% or more.

4. The prismatic battery according to any one of claims 1 to 3, wherein the openings of the case main body and the sealing plates are each one, the sealing plate faces the first surface, the negative electrode active material layer further has a first surface side region provided in an end portion of the first surface in a strip shape, the first surface side region does not contain the Si-containing material, or the Si-containing material is contained at a lower rate in the first surface side region than in the central region.

5. The prismatic battery according to claim 4, wherein in the first direction, when the entire width of the negative electrode active material layer is taken as 100%, the proportion of the width of the sealing plate side region and the proportion of the width of the first surface side region are each smaller than the proportion of the width of the central region.

6. The prismatic battery according to claim 5, wherein the proportion of the width of the two sealing plate side regions is each 10% or more.

7. The prismatic battery according to claim 5, wherein the laminated electrode body is disposed closer to the first surface than the sealing plate in the first direction, the proportion of the width of the first surface side region is larger than the proportion of the width of the sealing plate side region.

8. The prismatic battery according to any one of claims 1 to 3, wherein the openings of the case main body and the sealing plates are each two, the two sealing plates are disposed facing each other in a manner orthogonal to the first surface and the second surfaces, The above-mentioned side regions of the sealing plates are provided at the end of the first sealing plate and the end of the second sealing plate, respectively.

9. The prismatic battery according to claim 8, wherein In the above-mentioned first direction, when the entire width of the negative electrode active material layer is set to 100%, the proportion of the width of each of the two above-mentioned side regions of the sealing plates is less than the proportion of the width of the above-mentioned central region.

10. The prismatic battery according to claim 9, wherein The proportion of the width of each of the two above-mentioned side regions of the sealing plates is 10% or more.

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