Battery

Abstract

To provide a battery that is unlikely to be damaged or broken at a joint between a battery case and a sealing member.SOLUTION: A battery disclosed herein includes an electrode body including a positive electrode and a negative electrode, an electrolyte, a battery case 10 that houses the electrode body and the electrolyte and has an electrolyte injection hole 15, and a sealing member 16 that is joined to the periphery of the electrolyte injection hole 15 of the battery case 10 and seals the electrolyte injection hole 15. The battery case 10 includes a protrusion 14a that protrudes toward the electrode body around the electrolyte injection hole 15 on the side surface of the electrode body.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a battery.

Background Art

[0002] Conventionally, a battery is known that includes an exterior body having an opening, a sealing plate having an electrolyte injection hole and sealing the opening of the exterior body, a sealing member for sealing the electrolyte injection hole, and an electrode body and an electrolyte housed in the exterior body. In this regard, for example, in Patent Document 1, first, an electrode body is housed inside an exterior body and the opening of the exterior body is sealed with a sealing plate. Next, an electrolyte is injected through an electrolyte injection hole. Next, a sealing member is welded and joined to the periphery of the electrolyte injection hole to hermetically seal (seal) the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a battery having an electrolyte, for example, due to repeated charge and discharge or storage in a high-temperature environment, the electrolyte may volatilize and the battery may be filled with gas. As a result, when the internal pressure of the battery increases, the sealing plate may warp and the vicinity of the electrolyte injection hole may deform. As a result, there is a risk that the portion where the sealing member is welded and joined may be damaged or broken. According to the study by the present inventor, particularly in a high-capacity or large-sized battery used as a power source for vehicle driving or the like, such a tendency is remarkable because the size of the sealing plate becomes large or the amount of the electrolyte increases.

[0005] The present invention has been made in view of the above circumstances, and its main object is to provide a battery that suppresses deformation in the vicinity of the electrolyte injection hole of the battery case and is less likely to cause damage or breakage at the joint between the battery case and the sealing member. [Means for solving the problem]

[0006] The present invention provides a battery comprising: an electrode body including a positive electrode and a negative electrode; an electrolyte; a battery case housing the electrode body and the electrolyte and having an electrolyte injection hole; and a sealing member joined to the periphery of the electrolyte injection hole of the battery case and sealing the electrolyte injection hole. The battery case has a projection on the side surface of the electrode body that protrudes toward the electrode body around the electrolyte injection hole.

[0007] In this invention, a protrusion is provided on the electrode side surface of the battery case, projecting toward the electrode. This increases the rigidity of the sealing plate near the electrolyte injection hole, and relatively suppresses deformation when the internal pressure rises compared to a configuration without a protrusion. Therefore, damage or breakage of the joint between the battery case and the sealing member can be suppressed, and the reliability of the joint can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view showing a battery according to one embodiment. [Figure 2] This is a schematic longitudinal cross-section along the line II-II in Figure 1. [Figure 3] Figure 2 is a schematic longitudinal cross-sectional view showing the vicinity of the electrolyte injection hole. [Figure 4] This is a schematic perspective view of a partially fractured section showing the vicinity of the electrolyte injection hole. [Figure 5] This is a schematic perspective view showing the group of electrodes attached to the sealing plate. [Figure 6] This is an explanatory diagram illustrating a laser welding method according to one embodiment, where (A) represents the trajectory of the first welding and (B) represents the trajectory of the second welding. [Modes for carrying out the invention]

[0009] Hereinafter, preferred embodiments of the battery disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned herein but necessary for carrying out the present invention (e.g., general configuration and manufacturing process of a battery not characterizing the present invention) can be understood as design matters for those skilled in the art based on the prior art. The battery disclosed herein can be carried out based on the contents disclosed herein and common technical knowledge in the art.

[0010] In this specification, "battery" refers to all energy storage devices capable of extracting electrical energy, and is a concept that encompasses both primary and secondary batteries. Furthermore, in this specification, "secondary battery" refers to all energy storage devices capable of repeated charging and discharging, and is a concept that encompasses both so-called rechargeable batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as electric double-layer capacitors.

[0011] Furthermore, in the following drawings, the same reference numerals are used for members and parts that perform the same function, and redundant explanations may be omitted or simplified. In addition, in this specification, the notation "A~B" indicating a range shall encompass not only the meaning of A or greater and B or less, but also the meaning of "preferably greater than A" and "preferably less than B".

[0012] <Battery 100> Figure 1 is a perspective view of battery 100. Figure 2 is a schematic longitudinal cross-sectional view along line II-II in Figure 1. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, back, up, and down, respectively, and the symbols X, Y, and Z in the drawings represent the short side direction, the long side direction perpendicular to the short side direction, and the up and down direction of battery 100, respectively. However, these directions are merely for the convenience of explanation and do not in any way limit the installation configuration of battery 100.

[0013] As shown in Figure 2, the battery 100 comprises a battery case 10, an electrode group 20, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode current collector 50, a negative electrode current collector 60, and an electrolyte (not shown). The battery 100 is preferably a secondary battery, and more preferably a non-aqueous electrolyte secondary battery. In this case, the battery 100 is a lithium-ion secondary battery.

[0014] The battery case 10 is a housing that contains the electrode group 20 and the electrolyte. As shown in Figure 1, the battery case 10 has a flattened, bottomed rectangular parallelepiped (square) shape. A square shape is preferred for the battery case 10. The material of the battery case 10 can be the same as that used conventionally, and there are no particular restrictions. The battery case 10 is preferably made of metal, and more preferably of aluminum, aluminum alloy, iron, iron alloy, etc. The battery case 10 comprises an outer casing 12 having an opening 12h and a sealing plate (lid) 14 that seals the opening 12h. The battery case 10 preferably comprises an outer casing 12 having an opening 12h and a sealing plate 14 that seals the opening 12h, as in this embodiment.

[0015] As shown in Figure 1, the exterior body 12 comprises a bottom wall 12a, a pair of long side walls 12b extending from the bottom wall 12a and facing each other, and a pair of short side walls 12c extending from the bottom wall 12a and facing each other. The bottom wall 12a is substantially rectangular in shape. The bottom wall 12a faces the opening 12h. In a plan view, the area of ​​the long side walls 12b is larger than the area of ​​the short side walls 12c.

[0016] The sealing plate 14 is attached to the outer casing 12 so as to close the opening 12h of the outer casing 12. The sealing plate 14 faces the bottom wall 12a of the outer casing 12. The sealing plate 14 is substantially rectangular in plan view. The battery case 10 is integrated with the outer casing 12 by joining (preferably by welding) the sealing plate 14 to the periphery of the opening 12h. The battery case 10 is airtightly sealed.

[0017] As shown in FIG. 2, the sealing plate 14 is provided with an electrolyte injection hole 15, a discharge valve 17, and two terminal lead-out holes 18 and 19. The discharge valve 17 is configured to break when the pressure in the battery case 10 reaches or exceeds a predetermined value and discharge the gas in the battery case 10 to the outside. The terminal lead-out holes 18 and 19 penetrate the sealing plate 14 in the vertical direction Z. The terminal lead-out holes 18 and 19 have an inner diameter large enough to allow insertion of the positive electrode terminal 30 and the negative electrode terminal 40 before being attached to the sealing plate 14 (before caulking).

[0018] The electrolyte injection hole 15 is for injecting electrolyte after the sealing plate 14 is assembled to the exterior body 12. The electrolyte injection hole 15 is preferably formed in the sealing plate 14. Although not particularly limited, in the case of a high-capacity type used for in-vehicle applications or the like, in the battery case 10, the length in the short side direction X of the surface where the electrolyte injection hole 15 is formed (here, the sealing plate 14) is preferably 20 mm or more, and more preferably 25 mm or more. When the length in the short side direction X is long in this way, the sealing plate 14 is particularly likely to deform and warp when the internal pressure rises, and the load near the electrolyte injection hole 15 increases. Therefore, applying the technology disclosed herein is particularly effective.

[0019] FIG. 3 is a longitudinal sectional view schematically showing the vicinity of the electrolytic solution injection hole 15. FIG. 4 is a partially broken perspective view schematically showing the vicinity of the electrolytic solution injection hole 15. As shown in FIGS. 1 to 4, the electrolytic solution injection hole 15 is sealed with a sealing member (sealing cap) 16. The sealing member 16 is preferably made of metal, and more preferably made of, for example, aluminum or an aluminum alloy. As shown in FIG. 4, in a plan view, the outer shapes of the electrolytic solution injection hole 15 and the sealing member 16 are each substantially circular. The outer shape of the sealing member 16 is preferably circular. However, in other embodiments, it may have a shape other than circular. As shown in FIG. 3, the outer diameter R2 of the sealing member 16 is larger than that of the electrolytic solution injection hole 15. As shown in FIGS. 3 and 4, the electrolytic solution injection hole 15 is sealed here by joining (for example, welding) the sealing member 16 to the periphery of the electrolytic solution injection hole 15 of the sealing plate 14. The joining of the sealing member 16 can be performed by a method such as conventionally known laser welding.

[0020] As shown in FIG. 3, the sealing plate 14 of the battery case 10 has a protruding portion 14a, a recessed portion 14b, a first protrusion 14c1, and a second protrusion 14c2. The recessed portion 14b includes a first recessed portion 14b1, a second recessed portion 14b2, and a third recessed portion 14b3. The third recessed portion 14b3 is an example of a liquid retention recessed portion.

[0021] The protruding portion 14a is provided on the surface of the battery case 10 (specifically, the sealing plate 14) facing the electrode body group 20, that is, on the inner surface of the battery case 10 (the lower surface 14d of the sealing plate 14 in FIG. 3). The protruding portion 14a protrudes from the base portion (portion without irregularities) of the sealing plate 14 toward the side of the electrode body group 20 (downward in FIG. 3). By having the protruding portion 14a, the rigidity in the vicinity of the electrolytic solution injection hole 15 of the sealing plate 14 can be increased. Thereby, deformation in the vicinity of the sealing plate 14 can be suppressed. Therefore, it is possible to prevent the joint portion W between the sealing plate 14 and the sealing member 16 from being damaged or broken, and the reliability of the joint portion W can be enhanced.

[0022] As can be seen from Figures 3 and 4, in plan view, the outer shape of the projection 14a is approximately annular (specifically, approximately circular). As shown in Figure 3, the outer diameter R1 of the projection 14a is larger than that of the electrolyte injection hole 15. The projection 14a is provided around the electrolyte injection hole 15 so as to surround it. The electrolyte injection hole 15 penetrates the projection 14a in the vertical direction Z. Here, the outer diameter R1 of the projection 14a is larger than the outer diameter R2 of the sealing member 16. It is preferable that the outer diameter R1 of the projection 14a is larger than the outer diameter R2 of the sealing member 16. This allows for more effective suppression of deformation of the sealing plate 14 near the electrolyte injection hole 15. However, in other embodiments, the outer diameter R1 of the projection 14a may be the same as the outer diameter R2 of the sealing member 16, or it may be smaller than the outer diameter R2 of the sealing member 16.

[0023] As shown in Figure 3, in a cross-sectional view, when the thickness of the base portion (the portion without irregularities) of the sealing plate 14 is T1 and the thickness of the protruding portion 14a is T2, the ratio of T2 to T1 (T2 / T1) is preferably 0.6 or more, and more preferably 0.8 or more. The above ratio (T2 / T1) may be approximately 2 or less, for example, 1 or less. Furthermore, the thickness T2 of the protruding portion 14a is preferably 1 mm or more, and more preferably 1.5 mm or more. This makes it possible to more effectively suppress deformation near the electrolyte injection hole 15, and to demonstrate the effects of the technology disclosed herein at a higher level.

[0024] The recess 14b is provided on the outer surface of the battery case 10 (specifically the sealing plate 14) (the upper surface 14u of the sealing plate 14 in Figure 3). As can be seen from Figures 3 and 4, in plan view, the outer diameter of the recess 14b is larger than the electrolyte injection hole 15. The recess 14b is provided around the electrolyte injection hole 15 so as to surround it. In plan view, the outer diameter of the recess 14b is larger here than the outer diameter R1 of the protrusion 14a. The sealing member 16 is positioned in the recess 14b so as to close the second recess 14b2 and the third recess 14b3. By positioning the sealing member 16 inside the recess 14b, the protrusion height of the sealing member 16 can be suppressed. As a result, the joint W between the sealing plate 14 and the sealing member 16 is less likely to protrude from the upper surface of the battery case 10 (specifically the upper surface 14u of the sealing plate 14). Therefore, interference between the joint W and other members, which can cause damage or breakage to the joint W, can be better suppressed. However, in other embodiments, the sealing member 16 may be placed in addition to the recess 14b.

[0025] The first projection 14c1 is provided within the recess 14b. As can be seen from Figures 3 and 4, in plan view, the outer shape of the first projection 14c1 is approximately annular (specifically, approximately circular). The first projection 14c1 may have a portion of its approximately annular shape missing. The outer diameter of the first projection 14c1 is larger than that of the electrolyte injection hole 15. The first projection 14c1 is provided around the electrolyte injection hole 15 so as to surround it. As shown in Figure 3, the outer diameter of the first projection 14c1 is smaller here than the outer diameter R1 of the protruding portion 14a. The inner diameter of the first projection 14c1 is approximately the same as the outer diameter R2 of the sealing member 16. The inner circumferential wall surface of the first projection 14c1 (the side of the electrolyte injection hole 15) extends vertically from the upper surface 14u. The sealing member 16 is fitted inside the first projection 14c1. The first projection 14c1 also functions as a guide to indicate the position for fitting the sealing member 16. The inner edge of the first projection 14c1 is flush with the upper surface 16u of the sealing member 16.

[0026] The first projection 14c1 is joined (preferably by welding) to the outer edge of the sealing member 16. A joint W is formed at the boundary between the first projection 14c1 and the outer edge of the sealing member 16. The presence of the first projection 14c1 stabilizes the penetration shape when welding is performed and suppresses the occurrence of undercuts. Therefore, the joint W can be formed with high precision. The joint W is formed in a substantially annular shape (specifically, a substantially circular shape) along the first projection 14c1. As described in the manufacturing method described later, the joint W may have a substantially annular portion and an overhanging portion formed at a position protruding from the substantially annular portion. As shown in Figure 3, in a cross-sectional view, it is preferable that the joint W is formed to be shorter than the thickness (length in the vertical direction Z) of the sealing member 16.

[0027] Within the recess 14b, a first recess 14b1 is provided on the outer periphery side of the first projection 14c1. The first recess 14b1 is not closed by the sealing member 16 and is open to the outside. Having the first recess 14b1 improves workability when forming the joint W. It also prevents the joint W from being damaged or broken by interference with other components when using the battery, etc.

[0028] The second projection 14c2 is provided within the recess 14b. The second projection 14c2 is provided so as to face the surface of the sealing member 16 on the electrode group 20 side (the inner surface, the lower surface 16d in Figure 3). Preferably, the second projection 14c2 is in contact with the lower surface 16d of the sealing member 16. The second projection 14c2 separates the second recess 14b2 and the third recess 14b3. As shown in Figure 3, the outer diameter of the second projection 14c2 is smaller here than the outer diameter R1 of the protruding portion 14a. The outer diameter of the second projection 14c2 is smaller than the outer diameter R2 of the sealing member 16. Having the second projection 14c2 allows the position of the sealing member 16 to be stabilized. In particular, the height of the sealing member 16 (position in the vertical direction Z) can be adjusted to stably make the first projection 14c1 and the upper surface 16u of the sealing member 16 flush.

[0029] As can be seen from Figures 3 and 4, in plan view, the outer shape of the second projection 14c2 is approximately annular (specifically, approximately circular). It is preferable that the outer shape of the second projection 14c2 is approximately annular. The outer diameter of the second projection 14c2 is larger than that of the electrolyte injection hole 15. The second projection 14c2 is located on the inner circumference side of the first projection 14c1. The second projection 14c2 is located between the outer edge of the electrolyte injection hole 15 and the first projection 14c1. The second projection 14c2 is located around the electrolyte injection hole 15 so as to surround it. According to the inventor's research, in the manufacturing process of the battery 100, when the battery 100 is transported or restrained before the electrolyte injection hole 15 is sealed with the sealing member 16, the electrolyte may reach the upper end of the electrolyte injection hole 15. The presence of the second projection 14c2 prevents the first projection 14c1 or the joint W from coming into contact with the electrolyte, even when the electrolyte reaches the upper end of the electrolyte injection hole 15. Therefore, the occurrence of welding defects can be suppressed, and the reliability of the joint W can be further improved.

[0030] As shown in Figure 4, it is preferable that the second projection 14c2 has a notch N formed in a part of it. The notch N may be one or two or more. The notches N may be provided point-symmetrically in a plan view. The notch N can function as an escape route for electrolyte gases that have vaporized due to the heat during laser welding or for expanded gases. In addition, even if the electrolyte reaches the second projection 14c2, the electrolyte can be returned to the outer casing 12 side through the notch N. The wall surface of the second projection 14c2 on the side of the electrolyte injection hole 15 is inclined linearly toward the electrolyte injection hole 15. The second projection 14c2 is sloped. This allows the electrolyte that has reached the second projection 14c2 to flow quickly and appropriately toward the side of the electrolyte injection hole 15, making it difficult for electrolyte to accumulate near the second projection 14c2.

[0031] A second recess 14b2 is provided on the outer circumference of the second projection 14c2. The second recess 14b2 is provided with a first space S1, which is partitioned by the outer wall surface of the second projection 14c2 and the lower surface 16d of the sealing member 16. The first space S1 is the space enclosed by the second recess 14b2 and the lower surface 16d of the sealing member 16. More specifically, it is the space enclosed by the upper surface 14u of the sealing plate 14, the outer wall surface of the second projection 14c2, the vertical wall surface on the inner circumference of the first projection 14c1, and the lower surface 16d of the sealing member 16. In plan view, the outer shape of the first space S1 is preferably approximately annular (specifically, approximately circular). The first space S1 is located directly below the joint W. The first space S1 can function as a reservoir for accumulating electrolyte that has entered the gap between the second projection 14c2 and the lower surface 16d of the sealing member 16. This prevents the electrolyte from crawling up the lower surface 16d of the sealing member 16 to the first projection 14c1 or the joint W. The volume of the first space S1 is 2 mm 3 The above is preferable, 5 mm 3 The above is preferable.

[0032] A third recess 14b3 is provided on the inner circumference side (the side of the electrolyte injection hole 15) of the second projection 14c2. In the third recess 14b3, the portion where the electrolyte injection hole 15 is provided is defined by the extension of the base portion (the portion without irregularities) at the bottom of the third recess 14b3. A second space S2 is provided in the third recess 14b3, partitioned by the lower surface 16d of the sealing member 16. The second space S2 is the space enclosed by the third recess 14b3 and the lower surface 16d of the sealing member 16. The second space S2 is in communication with the electrolyte injection hole 15. The second space S2 can function as a reservoir for the electrolyte that has reached the upper end of the electrolyte injection hole 15. By having the third recess 14b3, it becomes more difficult for the electrolyte to reach the second projection 14c2, and consequently, it is possible to suppress the electrolyte from adhering to the joint W. It is preferable that the volume of the second space S2 is larger than the volume of the first space S1. The volume of the second space S2 is 30 mm 3 The above is preferable, 50 mm 3 The above is preferable.

[0033] As shown in Figure 3, a central projection 16a is formed on the inner surface of the sealing member 16 (lower surface 16d in Figure 3), projecting toward the electrolyte injection hole 15 at its center. The outer shape of the central projection 16a is approximately circular. As shown in Figure 3, the outer diameter of the central projection 16a is smaller than that of the electrolyte injection hole 15. The central projection 16a is located directly above the electrolyte injection hole 15. The lower end of the central projection 16a is located above the upper end of the electrolyte injection hole 15. A central recess 16b is provided on the outer surface of the portion where the central projection 16a is formed (upper surface 16u in Figure 3). This makes it more difficult for the sealing member 16 to deform when the internal pressure rises, and the reliability of the joint W can be further improved.

[0034] The electrolyte can be the same as conventional electrolytes and is not particularly limited. Typically, the electrolyte is a non-aqueous electrolyte containing a non-aqueous solvent and a supporting salt (electrolyte salt). However, it may also be an aqueous electrolyte containing an aqueous solvent. The non-aqueous solvent includes, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. It is preferable that the non-aqueous solvent contains carbonates. In particular, it is preferable that it contains cyclic carbonates and linear carbonates. The supporting salt is, for example, a fluorine-containing lithium salt such as lithium hexafluoride phosphate (LiPF6). The electrolyte may further contain additives as needed.

[0035] The positive terminal 30 is located at one end of the sealing plate 14 in the long side direction Y (the left end in Figures 1 and 2). The negative terminal 40 is located at the other end of the sealing plate 14 in the long side direction Y (the right end in Figures 1 and 2). As shown in Figure 2, the positive terminal 30 and the negative terminal 40 extend from the inside to the outside of the sealing plate 14 through terminal lead holes 18 and 19. The positive terminal 30 and the negative terminal 40 are crimped to the peripheral portion surrounding the terminal lead holes 18 and 19 of the sealing plate 14 by a crimping process. Crimped portions 30c and 40c are formed at the ends of the positive terminal 30 and the negative terminal 40 on the side of the outer casing 12 (the lower end in Figure 2).

[0036] As shown in Figure 2, the positive terminal 30 is electrically connected to the positive electrode (not shown) of the electrode group 20 via the positive current collector 50 inside the casing 12. The negative terminal 40 is electrically connected to the negative electrode (not shown) of the electrode group 20 via the negative current collector 60 inside the casing 12. The positive terminal 30 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90. The negative terminal 40 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90.

[0037] Figure 5 is a schematic perspective view showing an electrode group 20 attached to a sealing plate 14. The electrode group 20 has multiple electrodes. The configuration and shape of the electrodes can be the same as in the conventional design and are not particularly limited. Here, the electrode group 20 has three electrodes 20a, 20b, and 20c. However, the number of electrodes arranged inside one outer casing 12 is not particularly limited and may be one, two, or four or more. When multiple electrodes are provided inside one outer casing 12, the size of the sealing plate 14 increases, or the amount of electrolyte increases, which can easily cause an increase in internal pressure. Therefore, applying the technology disclosed herein is particularly effective. Here, the electrodes 20a, 20b, and 20c are electrically connected in parallel. The electrodes 20a, 20b, and 20c each have a flattened shape. Here, the electrodes 20a, 20b, and 20c are wound electrodes. The electrode bodies 20a, 20b, and 20c are each positioned inside the outer casing 12 with their winding axes oriented approximately parallel to the long side direction Y.

[0038] Although not shown in the diagram, the electrode bodies 20a, 20b, and 20c each have a positive electrode, a negative electrode, and a separator. In this embodiment, the electrode bodies 20a, 20b, and 20c are constructed by stacking a strip-shaped positive electrode and a strip-shaped negative electrode with a strip-shaped separator in between, and winding them around a winding axis. The winding axis direction is approximately parallel to the long side direction Y. However, in other embodiments, the electrode bodies 20a, 20b, and 20c may be laminated electrode bodies in which multiple rectangular (typically rectangular) positive electrodes and multiple rectangular (typically rectangular) negative electrodes are stacked in an insulated state.

[0039] The positive electrode can be the same as conventional ones and is not particularly limited. Typically, the positive electrode has a positive electrode core and a positive electrode active material layer fixed to at least one surface of the positive electrode core. The positive electrode core is strip-shaped. The positive electrode core is preferably made of metal, and more preferably of metal foil. In this case, the positive electrode core is aluminum foil. Multiple positive electrode tabs protruding toward one side in the long side direction Y (left side in Figures 2 and 5) are stacked on the positive electrode core to form a positive electrode tab group 23. The positive electrode tab group 23 is electrically connected to the positive electrode terminal 30 via a positive electrode current collector 50. The positive electrode active material layer contains a positive electrode active material capable of reversibly intercepting and releasing charge carriers. Examples of positive electrode active materials include lithium transition metal composite oxides. The positive electrode active material layer may also contain various additives other than the positive electrode active material, such as binders and conductive materials.

[0040] The negative electrode can be the same as conventional ones and is not particularly limited. Typically, the negative electrode has a negative electrode core and a negative electrode active material layer fixed to at least one surface of the negative electrode core. The negative electrode core is strip-shaped. The negative electrode core is preferably made of metal, and more preferably of metal foil. In this case, the negative electrode core is copper foil. A plurality of negative electrode tabs are laminated on the negative electrode core, protruding toward one end in the long side direction Y (right side in Figures 2 and 5), forming a negative electrode tab group 25. The negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via a negative electrode current collector 60. The negative electrode active material layer contains a negative electrode active material capable of reversibly intercepting and releasing charge carriers. Examples of negative electrode active materials include carbon materials such as graphite. The negative electrode active material layer may also contain various additive components other than the negative electrode active material, such as binders, thickeners, dispersants, etc.

[0041] The separator is placed between the positive electrode and the negative electrode. The separator is a component that insulates the positive electrode from the negative electrode. As the separator, a porous sheet made of polyolefin resin such as polyethylene (PE) or polypropylene (PP) is preferred.

[0042] As shown in Figures 2 and 5, the positive electrode current collector 50 constitutes a conductive path that electrically connects the positive electrode tab group 23 and the positive electrode terminal 30. The positive electrode current collector 50 comprises a positive electrode first current collector 51 and a positive electrode second current collector 52. The positive electrode first current collector 51 is attached to the inner surface of the sealing plate 14. The positive electrode second current collector 52 extends along the short side wall 12c of the outer casing 12. The positive electrode second current collector 52 is attached to the electrode bodies 20a, 20b, and 20c, respectively.

[0043] As shown in Figures 2 and 5, the negative electrode current collector 60 constitutes a conductive path that electrically connects the negative electrode tab group 25 and the negative electrode terminal 40. The negative electrode current collector 60 comprises a negative electrode first current collector 61 and a negative electrode second current collector 62. The configuration of the negative electrode first current collector 61 and the negative electrode second current collector 62 may be equivalent to that of the positive electrode first current collector 51 and the positive electrode second current collector 52 of the positive electrode current collector 50.

[0044] <Method for manufacturing battery 100> The battery 100 can be manufactured, for example, by a manufacturing method that includes a battery case 10 (i.e., an outer casing 12 and a sealing plate 14) as described above, a sealing member 16, an electrode group 20, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode current collector 50, a negative electrode current collector 60, and an electrolyte (not shown), and includes a housing step and a sealing step.

[0045] In the housing process, for example, first the positive electrode second current collector 52 is joined to the positive electrode tab group 23 of the electrode body group 20, and the negative electrode second current collector 62 is joined to the negative electrode tab group 25. Next, the positive electrode terminal 30, the negative electrode terminal 40, the positive electrode first current collector 51, and the negative electrode first current collector 61 are attached to the sealing plate 14. This integrates the sealing plate 14, the positive electrode terminal 30, the negative electrode terminal 40, and the electrode body group 20. Next, the electrode body group 20 integrated with the sealing plate 14 is housed in the internal space of the outer casing 12, and the opening 12h of the outer casing 12 is sealed with the sealing plate 14. Sealing can be performed by welding, such as laser welding.

[0046] In the sealing process, first, the electrolyte is injected through the electrolyte injection hole 15. Next, the sealing member 16 is joined to the periphery of the electrolyte injection hole 15 of the sealing plate 14 to form a joint W. This seals the electrolyte injection hole 15 and seals the battery 100. In one embodiment, the sealing joint is formed by welding the interface between the sealing plate 14 and the sealing member 16 by laser welding, which involves irradiating the interface with laser light. When forming an annular joint W along the first projection 14c1, it is preferable to weld the annular portion in two or more stages. Welding in multiple stages makes it easier to release the electrolyte gas that has evaporated due to the heat during laser welding, thereby suppressing the occurrence of welding defects.

[0047] Figure 6 is an explanatory diagram illustrating the laser welding method, where (A) shows the trajectory of the first welding and (B) shows the trajectory of the second welding. In this embodiment, as shown in Figure 6(A), in the first laser welding, welding is started at a position away from the interface between the sealing plate 14 and the sealing member 16, as shown in (1), and the laser light is irradiated to draw a line-shaped trajectory on the interface between the sealing plate 14 and the sealing member 16. Next, after folding back as shown in (2), a semicircular trajectory is drawn further as shown in (3). Then, welding is ended at a position away from the interface, as shown in (4). Also, as shown in Figure 6(B), in the second laser welding, welding is started at a position away from the interface between the sealing plate 14 and the sealing member 16, as shown in (1), and a semicircular trajectory is drawn on the interface between the sealing plate 14 and the sealing member 16, as shown in (2). Then, welding is ended at a position away from the interface, as shown in (3).

[0048] In this way, by starting welding at a position away from the interface between the sealing plate 14 and the sealing member 16, and ending the welding at a position away from the interface, it is possible to prevent excessive laser beam irradiation at the starting and ending points. Therefore, it is possible to prevent holes from forming in the battery case 10 (sealing plate 14) or the sealing member 16, which would result in insufficient airtightness of the battery 100. In this embodiment, the welding trajectory is changed between the first and second passes, but in other embodiments, for example, the laser welding shown in Figure 6(A) may be performed twice to form the annular joint W, or the laser welding shown in Figure 6(B) may be performed twice to form the annular joint W. Furthermore, the laser welding can be divided into three or more passes.

[0049] <Uses of Battery 100> Battery 100 can be used for various purposes, but it is particularly suitable as a power source (driving power supply) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0050] 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 forms. The present invention can be implemented based on the contents disclosed herein and common technical knowledge in the art. The technologies described in the claims include various modifications and changes to the embodiments illustrated above. For example, it is possible to replace parts of the above embodiments with other modifications, and it is also possible to add other modifications to the above embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0051] For example, in the embodiment described above, as shown in Figure 3, the joint W was formed to be shorter than the thickness of the sealing member 16. In other words, the joint W was formed so as not to reach the first space S1. However, it is not limited to this. In other embodiments, the joint W may be formed to be longer than the thickness of the sealing member 16 and reach the first space S1. Furthermore, the joint W may be formed to be longer than the length of the vertical wall surface on the inner circumference side of the first projection 14c1. According to the inventors' research, even if laser welding is performed with an electrolyte present in the first space S1, the sealing plate 14 and the sealing member 16 are separated by the first space S, so the risk of welding defects is low. Therefore, even in such embodiments, the effects of the technology disclosed herein can be appropriately demonstrated, as in the embodiment described above.

[0052] As described above, specific embodiments of the technology disclosed herein include those described in the following sections. Item 1: A battery comprising an electrode body including a positive electrode and a negative electrode, an electrolyte, a battery case housing the electrode body and the electrolyte and having an electrolyte injection hole, and a sealing member joined to the periphery of the electrolyte injection hole of the battery case and sealing the electrolyte injection hole, wherein the battery case has a projection on the side surface of the electrode body that protrudes toward the electrode body around the electrolyte injection hole. Item 2: The battery according to Item 1, wherein the battery case has a recess on its outer surface, and the electrolyte injection hole is located in the recess. Item 3: The battery according to item 1 or 2, wherein a first projection is provided in the recess so as to surround the electrolyte injection hole, and the outer edge of the sealing member and the first projection are welded together. Item 4: The battery according to item 2 or 3, wherein the recess is provided with a second projection that faces the side of the sealing member facing the electrode body, around the electrolyte injection hole. Item 5: The battery described in Item 4, wherein the second projection is substantially annular in plan view. Item 6: The battery according to item 4 or 5, wherein the second projection has a notch formed in part. Item 7: The battery according to any one of items 4 to 6, wherein the recess has a first space partitioned by the outer peripheral wall surface of the second projection of the battery case and the electrode side surface of the sealing member. Item 8: A battery according to any one of items 4 to 7, having a fluid retention recess located on the side of the electrolyte injection hole than the second projection. Item 9: The battery according to item 8, having a second space enclosed by the liquid-retaining recess and the side of the sealing member on the electrode body side. Item 10: A battery according to any one of items 1 to 9, wherein, in a plan view, the outer shape of the protrusion is larger than the outer shape of the sealing member. [Explanation of Symbols]

[0053] 10 Battery Case 12 Exterior 14 Sealing plate 14a Protrusion 14b recess 14c1 1st protrusion 14c2 2nd protrusion 15 Electrolyte injection hole 16 Sealing member 20 Electrode group 20a, 20b, 20c electrode body 100 batteries

Claims

1. An electrode body including a positive electrode and a negative electrode, Electrolyte and A battery case containing the electrode body and the electrolyte, and having an electrolyte injection port, A sealing member is joined to the periphery of the electrolyte injection hole of the battery case and seals the electrolyte injection hole, Equipped with, The battery case has a projection on the electrode side that protrudes toward the electrode around the electrolyte injection hole, The battery case has a recess on its outer surface, The electrolyte injection hole is located in the recess, The recess is provided with a first projection that surrounds the electrolyte injection hole. The outer edge of the sealing member and the first projection are welded together. A battery in which the sealing member has an outer surface on the side opposite to the surface facing the electrolyte injection hole, and in a cross-sectional view along the penetrating direction of the electrolyte injection hole, the entire sealing member including the outer surface is located within the recess.

2. An electrode body including a positive electrode and a negative electrode, Electrolyte and A battery case containing the electrode body and the electrolyte, and having an electrolyte injection port, A sealing member is joined to the periphery of the electrolyte injection hole of the battery case and seals the electrolyte injection hole, Equipped with, The battery case has a projection on the electrode side that protrudes toward the electrode around the electrolyte injection hole, The battery case has a recess on its outer surface, The electrolyte injection hole is located in the recess, The recess is provided with a second projection facing the electrode-side surface of the sealing member around the electrolyte injection hole, and a space exists between the electrode-side surface of the sealing member and the bottom surface of the recess of the battery case, located closer to the electrolyte injection hole than the second projection, and is separated by the electrode-side surface of the sealing member and the bottom surface of the recess of the battery case, and is in communication with the electrolyte injection hole. A battery in which the sealing member has an outer surface on the side opposite to the surface facing the electrolyte injection hole, and in a cross-sectional view along the penetrating direction of the electrolyte injection hole, the entire sealing member including the outer surface is located within the recess.

3. When the thickness of the base portion of the surface of the battery case where the electrolyte injection hole is provided is T1, and the thickness of the protruding portion is T2, the ratio of T2 to T1 (T2 / T1) is 0.8 or more. The battery according to claim 1 or 2.

4. The sealing member has a protrusion in the portion facing the electrolyte injection hole, The battery according to claim 1 or 2.

5. The sealing member has a recess in the center of its outer surface, The battery according to claim 1 or 2.

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