Battery

Abstract

The invention relates to the technical field of batteries, and discloses a battery, comprising: a battery cell; the shell comprises a shell body and a cover body, and the cover body and the shell body are connected to form a sealing cavity for accommodating the battery cell; wherein the shell comprises a shell main body and a first reinforcing part, and the first reinforcing part is connected to the edge of the shell main body; in the thickness direction of the shell, the shell main body is provided with a first wall surface and a second wall surface which are opposite; the first reinforcing part is provided with a first side surface and a second side surface which are opposite; the first side surface is positioned on one side surface of the first reinforcing part away from the sealing cavity; the first side surface comprises a connecting surface and a first cambered surface, the second side surface comprises a second cambered surface, two ends of the first cambered surface are respectively connected with the connecting surface and the first wall surface, and one end of the second cambered surface is connected with the second wall surface; the length of the connecting surface is greater than the thickness of the shell main body. According to the invention, the risks of shell deformation and sealing failure can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery. BACKGROUND

[0002] With the rapid development of battery technology, secondary batteries have become an indispensable part of daily life, such as mobile phones, tablets, laptops and digital cameras, etc. electronic devices, which need secondary batteries to provide power. Among them, the hard shell battery belongs to one of the secondary batteries.

[0003] The shell of the hard shell battery usually includes a shell and a cover body (top cover) covering the opening of the two ends of the shell. The cover body and the two ends of the shell are respectively welded to form a sealed cavity containing the battery cell.

[0004] However, in the battery drop test, the cover body is forced to the two ends of the shell, resulting in deformation of the shell, and the combination of the shell and the cover body is weak. When the shell is deformed under stress, the joint between the cover body and the shell is prone to cracking, resulting in sealing failure. SUMMARY

[0005] Therefore, the present application provides a battery to solve the problem that the shell of the battery is prone to deformation and the joint between the cover body and the shell is prone to cracking.

[0006] The present application provides a battery, comprising: a battery cell; a shell comprising a shell and a cover body, the shell being provided with an opening along at least one side in a first direction, the cover body being connected with the shell and covering the opening, the shell and the cover body forming a sealed cavity containing the battery cell; wherein the shell comprises a shell body and a first reinforcing part, the first reinforcing part being connected to the edge of the shell body along the first direction, the first reinforcing part being folded towards the side close to the sealed cavity or folded towards the side away from the sealed cavity, at least part of the first reinforcing part surrounding the periphery of the shell body; along the thickness direction of the shell body, the shell body has opposite first and second wall surfaces; the first reinforcing part has opposite first and second side surfaces, the first side surface being located on the side surface of the first reinforcing part away from the sealed cavity; the first side surface comprises a connecting surface and a first curved surface, the second side surface comprises a second curved surface, the two ends of the first curved surface being connected with the connecting surface and the first wall surface respectively, one end of the second curved surface being connected with the second wall surface; along the thickness direction of the shell body, the cover body is connected with the connecting surface, and the length of the connecting surface is greater than the thickness of the shell body.

[0007] In some embodiments, the length of the connecting surface along the thickness direction is L, satisfying 0.1mm≤L≤0.5mm; and / or, the thickness of the shell body along the thickness direction is D1, satisfying 0.075mm≤D1≤0.4mm; and / or, the angle between the connecting surface and the first wall surface is α1, satisfying 85°≤α1≤95°.

[0008] In some embodiments, the radius of the arc corresponding to the first arc surface is R1, and the radius of the arc corresponding to the second arc surface is R2, satisfying that R2 < R1, 1mm ≤ R1 ≤ 3mm, and 0.5mm ≤ R2 ≤ 3mm; and / or, the angle between the tangent at the connection point of the first arc surface and the connecting surface and the connecting surface is α3, satisfying that α3 ≥ 0; and / or, the angle between the tangent at the connection point of the second arc surface and the connecting surface and the connecting surface is α4, satisfying that α4 ≥ 0.

[0009] In some embodiments, the cover and the connecting surface are welded together by a connecting portion. On a first cross-section parallel to the first direction and passing through the connecting portion, along the thickness direction, the connecting portion has a first point located at the connection between the cover and the connecting surface and close to the sealing cavity, and a second point away from the sealing cavity. The distance between the first point and the second point is W, and the thickness of the shell body is D1, satisfying W≥0.2D1; and / or, the first reinforcing portion is bent toward the side close to the sealing cavity; along the thickness direction, the distance between the first point and the end of the connecting surface away from the first arc surface is b, satisfying b≥10μm; and / or, the first reinforcing portion is bent toward the side away from the sealing cavity; along the thickness direction, the distance between the second point and the end of the connecting surface close to the first arc surface is b, satisfying b≥10μm; and / or, along the thickness direction, the distance between the second point and the second wall surface is e, satisfying e≤0.5D1.

[0010] In some embodiments, the end of the connecting surface away from the first arc surface intersects the end of the second arc surface away from the second wall surface; or, the first reinforcing part further includes a first positioning surface, the two ends of which are respectively connected to the end of the connecting surface away from the first arc surface and the end of the second arc surface away from the second wall surface.

[0011] In some embodiments, the cover is provided with a protruding structure that protrudes toward one side of the battery cell, the protruding structure being located inside the opening and abutting against the first positioning surface.

[0012] In some embodiments, the protruding structure is in a continuous ring shape; or, multiple protruding structures are provided, and the multiple protruding structures are distributed intermittently in a ring shape along the circumferential distance of the opening; and / or, the surface of the protruding structure is an arc surface; and / or, the included angle between the first positioning surface and the connecting surface is α2, satisfying 80°≤α2≤120°; and / or, along the first direction, the thickness of the first positioning surface is D2, and the thickness of the shell body is D1, satisfying 0.1D1≤D2≤D1.

[0013] In some embodiments, on the same projection plane perpendicular to the first direction, the orthographic projection of the first arc surface is located on the inner side of the orthographic projection of the first wall surface near the cell; and / or, on the same projection plane perpendicular to the first direction, the orthographic projection of the second arc surface is located on the inner side of the orthographic projection of the second wall surface near the cell; and / or, both the first arc surface and the second arc surface protrude outwards away from the cell.

[0014] In some embodiments, an electrolyte is disposed within the accommodating space of the outer casing. The electrolyte includes ethylene carbonate, and the ethylene carbonate accounts for 5% to 30% of the mass of the electrolyte, based on the mass of the electrolyte.

[0015] In some embodiments, the housing is provided with openings on opposite sides along the first direction; two covers are provided, the two covers are respectively connected to opposite sides of the housing along the first direction and close the corresponding openings; the housing further includes a second reinforcing part, the first reinforcing part and the second reinforcing part are respectively connected to opposite sides of the housing body along the first direction, the second reinforcing part is bent toward the side away from the sealing cavity, and the first reinforcing part is bent toward the side close to the sealing cavity.

[0016] Beneficial effects: The present invention has a first reinforcing part in the shell that bends toward or away from the sealing cavity. The cover is connected to the first reinforcing part to close the shell opening. In the battery drop test, the first reinforcing part can alleviate or offset the force of the drop, reducing the risk of shell deformation. Moreover, the length of the connecting surface is greater than the thickness of the shell body, which can increase the joint area (such as the welding area) between the cover and the first reinforcing part. This can not only facilitate the machine to position the connecting surface, but also reduce the risk of sealing failure due to cracking at the joint between the cover and the first reinforcing part. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the battery structure according to an embodiment of the present invention; Figure 2 This is an exploded view of the battery according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the shell structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the shell portion structure according to another embodiment of the present invention; Figure 5 for Figure 3 Enlarged view of a portion of the image; Figure 6 for Figure 4 Enlarged view of a portion of the image; Figure 7 This is a schematic diagram of the positioning structure of the shell and cover in an embodiment of the present invention; Figure 8 This is a schematic diagram of the connection structure between the shell and the cover in an embodiment of the present invention; Figure 9 This is a simplified diagram of the protruding structure on the cover according to an embodiment of the present invention; Figure 10 This is a simplified diagram of the protruding structure on the cover according to another embodiment of the present invention; Figure 11 This is a simplified diagram of the protruding structure on the cover according to another embodiment of the present invention; Figure 12 This is a simplified diagram of the protruding structure on the cover of another embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 100 - Battery; 10 - Cell; 20 - Outer shell; 21 - Housing; 21a - Opening; 211 - Shell body; 212a - First reinforcing part; 212b - Second reinforcing part; 2111 - First wall surface; 2112 - Second wall surface; 2121 - First side surface; 2121a - First arc surface; 2121b - Connecting surface; 2122 - Second side surface; 2122a - Second arc surface; 22 - Cover; 221 - Protruding structure; 2123a - First positioning surface; c1 - First point; c2 - Second point. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In related technologies, the casing of a hard-shell battery typically includes a shell and a cover (top cover) with openings at both ends of the shell. The cover is welded to both ends of the shell to form a sealed cavity for accommodating the battery cells. However, in battery drop tests, the cover exerts force on both ends of the shell, causing deformation of the shell. Moreover, as the demand for high energy density in batteries increases, the shell wall thickness is being compressed to make the battery cells larger, thereby achieving higher energy density. However, the thinner shell wall thickness results in a narrower welding area between the cover and the shell ends, leading to weaker bonding force between the shell and the cover. When the shell is deformed under stress, the joint between the cover and the shell is prone to cracking, causing seal failure.

[0022] In response, the present invention has a reinforcing part in the shell that bends toward or away from the sealing cavity. The cover is connected to the reinforcing part to close the shell opening. In the battery drop test, the reinforcing part can alleviate or offset the force of the drop, reducing the risk of shell deformation. Moreover, the width of the reinforcing part is greater than the thickness of the shell, which can increase the joint area (such as the welding area) between the cover and the reinforcing part, reducing the risk of cracking at the joint between the cover and the reinforcing part, which leads to sealing failure.

[0023] Below, refer to Figures 1-12 The embodiments of the present invention will be described below.

[0024] This invention provides a battery 100, including a battery cell 10 and a casing 20.

[0025] In one specific example, the cell includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the positive electrode includes a positive current collector, a positive active layer, and a positive electrode tab extending from one side of the positive current collector; the negative electrode includes a negative current collector and a negative electrode tab extending from one side of the negative current collector; the negative electrode also includes a negative active layer located on at least one side surface of the negative current collector.

[0026] In some embodiments, the battery cell may be a wound core formed by stacking and winding a positive electrode sheet, a separator, and a negative electrode sheet; in other embodiments, the battery cell may be a stacked core formed by stacking a positive electrode sheet, a separator, and a negative electrode sheet. In a further embodiment, the stacked core includes a top layer and a bottom layer of electrode sheets along the thickness direction, the top layer and / or the bottom layer of electrode sheets may be a single-sided negative electrode sheet, the single-sided negative electrode sheet including a negative current collector and a negative active layer on the side surface of the negative current collector near the center of the battery cell.

[0027] In a specific example, the positive current collector may be, for example, aluminum foil, aluminum alloy foil, or composite current collector (e.g., aluminum-carbon composite current collector), and the thickness of the positive current collector may be, for example, 6μm-15μm (e.g., 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm).

[0028] In a specific example, the positive electrode active layer may include a positive electrode active material, such as lithium nickel cobalt manganese oxide (LiNi). 0.90 Co 0.05 Mn 0.05 At least one of the following: O2 (NCM955), NCM811, NCM622, NCM523, NCM111, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO2), lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel-type lithium manganese oxide, spinel-type lithium nickel manganese oxide, and lithium titanate.

[0029] In one specific example, the negative electrode current collector may be, for example, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a composite current collector. In one example, the thickness of the negative electrode current collector may be, for example, 4μm-10μm (e.g., 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm).

[0030] In one specific example, the negative electrode active layer may include a negative electrode active material, such as at least one selected from graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, spherical silicon-carbon, bulk silicon-carbon, Li-Al alloys, and metallic lithium. In embodiments where the negative electrode active material layer includes a silicon-carbon composite, the silicon content by mass fraction is 5%-50% (e.g., 5%, 5.5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%).

[0031] In one specific example, the separator includes a base membrane and adhesive layers on both sides of the base membrane. In a further embodiment, a ceramic layer and an adhesive layer are sequentially formed on a first side of the base membrane, and an adhesive layer is formed on a second side. The first side surface of the base membrane is disposed opposite to the positive electrode, and the second side surface of the base membrane is disposed opposite to the negative electrode. In some embodiments, the thickness of the separator is 5 μm-20 μm (e.g., 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, or 20 μm).

[0032] In one specific example, the battery also includes an electrolyte comprising a lithium salt and a solvent, wherein the solvent comprises at least one selected from ethylene carbonate, diethyl carbonate, or fluoroethylene carbonate. In another embodiment, the electrolyte further includes a nitrile additive. The nitrile additive comprises a C3 percentage based on the total mass of the electrolyte. C3 is 0.5%-8%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, or 8%. In some embodiments, the nitrile additive comprises, for example, at least one selected from butadionitrile, adiponitrile, and 1,3,6-hexanetrionitrile.

[0033] The outer casing 20 is a rigid casing, and its material can be metals such as aluminum, aluminum alloy, or stainless steel. The outer casing 20 includes a housing 21 and a cover 22. The housing 21 has an opening 21a on at least one side along the first direction X. The cover 22 is connected to the housing 21 and seals the opening 21a. The housing 21 and the cover 22 form a sealed cavity for accommodating the battery cell 10. In a specific example, the outer casing 20 can be L-shaped, stepped, rectangular, or arc-shaped.

[0034] The housing 21 includes a housing body 211 and a first reinforcing portion 212a. The first reinforcing portion 212a is connected to the edge of the housing body 211 along a first direction X, bent towards the side near the sealing cavity or towards the side away from the sealing cavity. At least a portion of the first reinforcing portion 212a surrounds the periphery of the housing body 211. As an example, the housing body 211 has the first reinforcing portion 212a on one edge along the first direction X. In another example, the housing body 211 has the first reinforcing portion 212a on both edges along the first direction X. The first reinforcing portion 212a may be integrally formed with the housing 21.

[0035] Along the thickness direction Y of the shell 21, the shell body 211 has a first wall surface 2111 and a second wall surface 2112. The first wall surface 2111 is the outer wall surface of the shell body 211 away from the sealing cavity, and the second wall surface 2112 is the inner wall surface of the shell body 211 near the sealing cavity.

[0036] The first reinforcing part 212a has a first side surface 2121 and a second side surface 2122, with the first side surface 2121 located on the side surface of the first reinforcing part 212a away from the sealing cavity. The first side surface 2121 includes a connecting surface 2121b and a first arcuate surface 2121a, and the second side surface 2122 includes a second arcuate surface 2122a. The two ends of the first arcuate surface 2121a are respectively connected to the connecting surface 2121b and the first wall surface 2111, and one end of the second arcuate surface 2122a is connected to the second wall surface 2112. In one example, refer to... Figure 6 The other end of the second arc surface 2122a can intersect with the connecting surface 2121b. In another example, refer to... Figure 5 The other end of the second arc surface 2122a can be connected to the connecting surface 2121b through the first positioning surface 2123a.

[0037] The cover 22 is connected to the connecting surface 2121b, and the length of the connecting surface 2121b is greater than the thickness of the shell body 211 along the thickness direction Y. The cover 22 and the connecting surface 2121b are connected to close the opening, and the two can be welded together. In other embodiments, the cover 22 and the connecting surface 2121b can also be glued together.

[0038] The present invention has a first reinforcing part 212a that bends toward the sealing cavity in the shell 21. The cover 22 is connected to the first reinforcing part 212a to close the opening of the shell 21. In the battery drop test, the first reinforcing part 212a can alleviate or offset the force of the drop, reducing the risk of deformation of the shell 21. Moreover, the length of the connecting surface 2121b is greater than the thickness of the shell body 211, which can increase the bonding area (such as the welding area) between the cover 22 and the first reinforcing part 212a, reducing the risk of cracking at the bonding point between the cover 22 and the first reinforcing part 212a, which leads to sealing failure.

[0039] In some embodiments, refer to Figure 5 Along the thickness direction Y, the length of the connecting surface 2121b is L, which satisfies 0.1mm≤L≤0.5mm. L can be any one of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm or any value between two of them.

[0040] If L is too small (less than 0.1 mm), the contact area between the cover 22 and the first reinforcing part 212a is too small, increasing the risk of sealing failure of the casing 21. If L is too large (greater than 0.5 mm), it occupies a large amount of internal space in the casing 21, resulting in low volume utilization and hindering the improvement of battery volumetric energy density. Therefore, 0.1 mm ≤ L ≤ 0.5 mm is beneficial for both improving the sealing effect and increasing battery volumetric energy density.

[0041] In some embodiments, the thickness of the shell body 211 along the thickness direction Y is D1, satisfying 0.075mm≤D1≤0.4mm. D1 can be any one of 0.075mm, 0.1mm, 0.15mm, 0.2mm, 0.3mm, 0.4mm, or a value between any two of them.

[0042] If D1 is too small, less than 0.075mm, the strength of the casing body 211 will be insufficient, and the risk of deformation will be high; if D1 is too large, greater than 0.4, it will encroach on the size of the cell 10, which is not conducive to improving the volumetric energy density of the battery; therefore, 0.075mm≤D1≤0.4mm is beneficial to improving the strength of the casing body 211, reducing the risk of deformation, and also improving the volumetric energy density of the battery.

[0043] In some embodiments, the angle between the connecting surface 2121b and the first wall surface 2111 is α1, satisfying 85°≤α1≤95°. α1 can be 85°, 86°, 87°, 88°, 89°, 90°, or 95°.

[0044] If α1 is too small, less than 85°, the first reinforcing part 212a is insufficient to offset the force of a drop, resulting in a high risk of deformation of the shell 21. If α1 is too large, greater than 95°, positioning the cover 22 and the first reinforcing part 212a during welding becomes difficult, negatively impacting welding quality and increasing the risk of seal failure. Therefore, by controlling α1 to be between 85° and 90°, the first reinforcing part 212a can effectively mitigate or offset the force of a drop, reducing the risk of deformation of the shell 21. Simultaneously, it reduces the difficulty of positioning the cover 22 and the first reinforcing part 212a, improving welding quality and thus enhancing seal reliability.

[0045] In some embodiments, the radius of the arc corresponding to the first arc surface 2121a is R1, and the radius of the arc corresponding to the second arc surface 2122a is R2, satisfying that R2 < R1, 1mm ≤ R1 ≤ 3mm, and 0.5mm ≤ R2 ≤ 3mm. R1 can be any one of 1mm, 1.3mm, 1.5mm, 2mm, 2.5mm, and 3mm, or any value between any two. R2 can be any one of 0.5mm, 1.3mm, 1.5mm, 2mm, 2.5mm, and 3mm, or any value between any two.

[0046] The values ​​1mm≤R1≤3mm and 0.5mm≤R2≤3mm ensure that the thickness of the first reinforcing part 212a is reduced, thereby reducing space occupation, improving space utilization, and increasing the volumetric energy density of the battery. R2<R1 means that the radius of the arc corresponding to the second arc surface 2122a on the inner side near the sealing cavity is greater than the radius of the arc corresponding to the first arc surface 2121a on the outer side away from the sealing cavity. This makes the thinning degree on the inner side of the first reinforcing part 212a greater than the thinning degree on the outer side. On the one hand, this reduces the space occupied by the first reinforcing part 212a inside the shell 21, and on the other hand, it ensures the strength of the first reinforcing part 212a.

[0047] Optionally, the angle between the tangent P1 at the connection point between the first arc surface 2121a and the connecting surface 2121b and the connecting surface 2121b is α3, satisfying α3≥0. This ensures the thinning of the first arc surface 2121a in the thickness direction.

[0048] Optionally, the angle between the tangent P2 at the connection point between the second arc surface 2122a and the connecting surface 2121b and the connecting surface 2121b is α4, satisfying α4≥0. This ensures the thinning of the second arc surface 2122a in the thickness direction.

[0049] In some embodiments, refer to Figure 8 The cover 22 and the connecting surface 2121b are welded together by the connecting part C. On the first cross section parallel to the first direction X and passing through the connecting part C, along the thickness direction Y, the connecting part C has a first point c1 located at the connection between the cover 22 and the connecting surface 2121b and close to the sealing cavity and a second point c2 far away from the sealing cavity. The distance between the first point c1 and the second point c2 is W. The thickness of the shell body 211 is D1, which satisfies that W≥0.2D1.

[0050] The larger W is (W≥0.2D1), the larger the welding area between the cover 22 and the first reinforcing part 212a, the higher the welding strength, and the better the sealing effect. However, W should not be too large. If it is close to the edge of the side wall, the risk of incomplete welding is high. Therefore, W≤D1 is required.

[0051] Along the thickness direction Y, the distance between the first point c1 and the end of the connecting surface 2121b away from the first arc surface 2121a is b, which satisfies b≥10μm. And / or, along the thickness direction Y, the distance between the second point c2 and the second wall surface 2112 is e, which satisfies e≤0.5D1.

[0052] In some embodiments, the first reinforcing part 212a is bent toward the side away from the sealing cavity; along the thickness direction Y, the distance between the second point c2 and the end of the connecting surface 2121b near the first arc surface 2121a is b, which satisfies b≥10μm.

[0053] The first reinforcing part 212a is bent toward the side closer to the sealing cavity; along the thickness direction Y, the distance between the first point c1 and the end of the connecting surface 2121b away from the first arc surface 2121a is b, which satisfies b≥10μm. The greater the distance between the first point c1 and the end of the connecting surface 2121b away from the first arc surface 2121a, the lower the risk of welding through the first reinforcing part 212a and the risk of false welding is also reduced; e≤0.5D1, the closer the second point c2 is to the second wall surface 2112, the more effective the welding area is ensured and the sealing effect is improved.

[0054] In some embodiments, refer to Figure 7 The cover 22 is provided with a protruding structure 221 that protrudes toward the side of the battery cell 10. The protruding structure 221 is located inside the opening 21a and abuts against the first positioning surface 2123a.

[0055] The raised structure 221 facilitates the positioning of the cover 22 and the first reinforcing part 212a, helps to ensure the bonding area between the cover 22 and the connecting surface 2121b, and improves the density effect.

[0056] Optional, refer to Figure 9 and Figure 11 The raised structure 221 is in a continuous ring shape. Alternatively, refer to... Figure 10 and Figure 12 Multiple protrusions 221 are provided, and the multiple protrusions 221 are distributed intermittently in a ring shape along the circumferential interval of the opening 21a.

[0057] The raised structure 221 is in a continuous ring shape, which facilitates one-time processing and improves manufacturing efficiency. Multiple raised structures 221 are in a discontinuous ring shape, which can improve the strength of the cover 22 and reduce the risk of deformation of the cover 22 compared to the raised structure 221.

[0058] Optionally, the surface of the raised structure 221 is curved. The curved surface can reduce stress concentration and ensure the strength of the cover 22.

[0059] Optionally, the included angle between the first positioning surface 2123a and the connecting surface 2121b is α2, satisfying 80°≤α2≤120°. α2 can be any one of 80°, 90°, 100°, 110°, and 120°, or a value between any two of them.

[0060] If α2 is too small (less than 80°) or too large (greater than 120°), the contact area between the first positioning surface 2123a and the protruding structure 221 will be too small, resulting in a large positioning deviation, which is not conducive to welding quality.

[0061] Optionally, along the first direction X, the thickness of the first positioning surface 2123a is D2, and the thickness of the shell body 211 is D1, satisfying 0.1D1≤D2≤D1.

[0062] The larger the thickness D2 of the first positioning surface 2123a, the better it is to increase the penetration depth during welding and improve the welding quality. However, if D2 is too large, it will encroach on the internal space of the battery and will not be conducive to improving the volumetric energy density of the battery. Therefore, 0.1D1≤D2≤D1 is beneficial to both improving the welding quality and improving the volumetric energy density of the battery.

[0063] In some embodiments, on the same projection plane perpendicular to the first direction X, the orthographic projection of the first arc surface 2121a is located on the inner side of the orthographic projection of the first wall surface 2111, closer to the cell 10. Thus, the first arc surface 2121a has a suitable thinning amount without occupying additional space.

[0064] In some embodiments, on the same projection plane perpendicular to the first direction X, the orthographic projection of the second arc surface 2122a is located on the inner side of the orthographic projection of the second wall surface 2112, closer to the cell 10. Thus, the second arc surface 2122a has a suitable thinning amount without occupying additional space.

[0065] In some embodiments, both the first arc surface 2121a and the second arc surface 2122a protrude outwards away from the battery cell 10. This results in the first arc surface 2121a and the second arc surface 2122a having a suitable amount of thinning.

[0066] In some embodiments, an electrolyte is disposed within the accommodating space of the outer casing 20. The electrolyte includes ethylene carbonate, and the mass percentage A of ethylene carbonate in the electrolyte is 5% to 30% based on the mass of the electrolyte. It can be any one or any combination of 5%, 10%, 15%, 20%, 25%, and 30%. Preferably, it is 5.5% to 25.7%.

[0067] The electrolyte includes ethylene carbonate (EC), which can prevent the electrolyte from corroding the first reinforcing part 212a, causing localized weakening of the material of the first reinforcing part 212a and affecting the consistency of strength.

[0068] In some embodiments, the housing 21 has openings 21a on opposite sides along the first direction X; two covers 22 are provided, each connected to opposite sides of the housing 21 along the first direction X and closing the corresponding openings 21a. The housing 21 also includes a second reinforcing part 212b, the first reinforcing part 212a and the second reinforcing part 212b are respectively connected to opposite sides of the housing body 211 along the first direction X, the second reinforcing part 212b is bent toward the side away from the sealing cavity, and the first reinforcing part 212a is bent toward the side closer to the sealing cavity.

[0069] The bending directions of the first reinforcing part 212a and the second reinforcing part 212b are opposite, so that when the first reinforcing part 212a and the second reinforcing part 212b are subjected to the force when the battery is dropped, the force acting on the shell body 211 cancels each other out, preventing the two sides of the shell body 211 from bending in the same direction and improving the bending strength of the shell body 211.

[0070] For example, the second reinforcing part 212b has a connecting surface 2121b, a first arc surface 2121a, and a second arc surface 2122a. In the second reinforcing part 212b, the two ends of the first arc surface 2121a are respectively connected to the connecting surface 2121b and the second wall surface 2112, and one end of the second arc surface 2122a is connected to the first wall surface 2111. The two covers 22 are respectively connected to the connecting surface 2121b of the first reinforcing part 212a and the connecting surface 2121b of the second reinforcing part 212b.

[0071] Example 1: Battery preparation: I. Preparation of the positive electrode sheet Lithium cobalt oxide (LCO), polyvinylidene fluoride (PVDF), and conductive carbon (SuperP) are dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 98:1:1 and stirred evenly to form a positive electrode slurry. This slurry is then uniformly coated onto both sides of the positive electrode current collector along its thickness direction. After drying and rolling, the positive electrode sheet is formed.

[0072] II. Preparation of the negative electrode sheet Silicon-carbon composite material, graphite, conductive carbon black, polyacrylic acid, sodium carboxymethyl cellulose and styrene-butadiene rubber are mixed in a mass ratio of 43.5:53.5:0.5:1.2:0.4:0.9. After being mixed with deionized water and stirred evenly to form a negative electrode slurry, it is uniformly coated on both sides of the copper foil of the negative electrode current collector along its thickness direction to form a negative electrode active material layer. After drying and rolling, it is made into a negative electrode sheet.

[0073] III. Preparation of Electrolyte An electrolyte was obtained by using 1M lithium hexafluorophosphate (LiPF6) as the lithium salt and ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a mass ratio of 1:1:1 as solvents. The total amount of electrolyte was counted, and ethylene carbonate with a mass content of 20% was used as a non-aqueous organic solvent.

[0074] IV. Battery Assembly The negative electrode, the first separator, the positive electrode, and the second separator are stacked in sequence and wound to form a battery cell. The battery cell is then encapsulated in a casing 20, followed by processes such as electrolyte injection, secondary sealing, formation, and sorting to obtain the battery. The casing 20 has covers 22 on both sides of its openings. The casing 21 includes a main body 211 and a first reinforcing part 212a. The cover 22 is connected to the first reinforcing part 212a via a connecting surface 2121b, the length of which is greater than the thickness of the main body 211. The length L of the connecting surface 2121b is 0.2 mm, the thickness D1 of the main body 211 is 0.1 mm, and the angle α1 between the connecting surface 2121b and the first wall surface 2111 is 90°.

[0075] The battery preparation methods in Examples 2-4 are the same as those in Example 1 and will not be described in detail here. Some parameter changes are shown in Table 1 below.

[0076] Test method for cell drop test pass rate: Twenty rechargeable batteries were randomly selected from each experimental group for drop testing: 1. Fully charge the battery cells, then place them in the fixture and drop them from a height of 1.5m. Drop each of the six sides of the battery cell six times. Test 10 battery cells per group and repeat the test 3 times per group.

[0077] 2. Test the change in open-circuit voltage of the battery cell before and after the drop test, and whether the battery cell catches fire. Record the battery cells that show a voltage drop or catch fire as failing. Record the number of qualified batteries and calculate the pass rate of the drop test. Record the results in Table 1. For example, 19 / 20 in Table 1 means that 19 out of 20 secondary batteries are qualified.

[0078] Battery sealing test method: Twenty rechargeable batteries were randomly selected from each experimental group for a sealing test, and no further tests were conducted on the selected batteries.

[0079] The sealing test specifically includes the following steps: 1) Determine the testing standards In the experiments of this application, the acceptable threshold for leakage rate was set to be less than or equal to 1×10-7 Pa·m3 / s; 2) Prepare equipment and materials The required equipment includes: a helium mass spectrometer leak detector (sensitivity ≤1×10-8Pa·m3 / s), a special fixture or vacuum chamber (suitable for the size of the battery cell to avoid deformation), high-purity helium (≥99.999%), a vacuum pump set, and battery cell pretreatment equipment.

[0080] 3) Battery pretreatment Cleaning: Removes residual electrolyte and dust from the surface; Drying: Bake at 70℃ for 2 hours to reduce internal moisture interference; Let stand: Cool to room temperature.

[0081] 4) Use the vacuum chamber method to detect leaks in the battery. The vacuum chamber method involves placing the battery in a sealed vacuum chamber, evacuating it, filling it with helium, and then monitoring the change in helium concentration inside the chamber to reflect the sealing performance of the battery casing. The method specifically includes the following steps: ① Secure the battery inside the vacuum chamber, ensuring the sealing ring fits snugly to prevent deformation caused by external pressure; ② Start the vacuum pump group and evacuate in stages. Specifically, first use a mechanical pump to pre-evacuate to 1 Pa, and then use a molecular pump to evacuate to ≤1×10-3 Pa. ③ Inject helium into the vacuum chamber to the set pressure, which is 500 Pa in this experiment; ④ Monitor the leakage rate with a helium mass spectrometer for 5 minutes; ⑤ Record and calculate the peak leakage rate Q. If it exceeds the threshold, it is considered unqualified. The calculation formula is: Q=(ΔC˙V) / t; where, ΔC: helium concentration change, V: vacuum chamber volume, t: detection time; ⑥ Use a helium recovery system to reduce losses and discharge residual helium to a safe concentration (<1%).

[0082] 5) Result Determination and Processing If the leakage rate is ≤1×10-7Pa·m3 / s, it is considered that there is no concentrated leakage point and it is qualified; otherwise, it is unqualified. Record the number of qualified batteries and calculate the pass rate of the sealing test, and record it in Table 1.

[0083] Table 1: Influence of various battery parameters on drop test pass rate and sealing pass rate

[0084] As shown in Table 1, by comparing Example 1 and Comparative Example 1, L is greater than D1, that is, the length of the connecting surface is greater than the thickness of the shell body, which can effectively reduce the risk of sealing failure caused by cracking during the drop test of the battery.

[0085] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application, are intended to cover non-exclusive inclusion. In the description of embodiments of this application, technical terms such as "first," "second," etc., are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of embodiments of this application, "a plurality of" means two or more, unless otherwise expressly and specifically defined. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0086] In the description of the embodiments of this application, the technical terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "circumferential," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed, operated, or used in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0087] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0088] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery (100) characterized in that, The battery comprises: an electric core (10); a shell (20) comprising a shell body (21) and a cover (22), the shell body (21) is provided with an opening (21a) on at least one side in a first direction (X), the cover (22) is connected with the shell body (21) and covers the opening (21a), and the shell body (21) and the cover (22) form a sealed cavity accommodating the electric core (10); wherein the shell body (21) comprises a shell main body (211) and a first reinforcing part (212a), the first reinforcing part (212a) is connected to the edge of the shell main body (211) in the first direction (X), and the first reinforcing part (212a) is bent towards the side close to the sealed cavity or bent towards the side away from the sealed cavity, and at least part of the first reinforcing part (212) surrounds the periphery of the shell main body (211); in the thickness direction (Y) of the shell body (21), the shell main body (211) has opposite first and second wall surfaces (2111 and 2112), and the first reinforcing part (212a) has opposite first and second side surfaces (2121 and 2122), and the first side surface (2121) is located on the side surface of the first reinforcing part (212a) away from the sealed cavity; the first side surface (2121) comprises a connecting surface (2121b) and a first arc surface (2121a), the second side surface (2122) comprises a second arc surface (2122a), and the two ends of the first arc surface (2121a) are connected with the connecting surface (2121b) and the first wall surface (2111) respectively, and one end of the second arc surface (2122a) is connected with the second wall surface (2112); the cover (22) is connected with the connecting surface (2121b), and the length of the connecting surface (2121b) in the thickness direction (Y) of the shell body (21) is greater than the thickness of the shell main body (211).

2. The battery according to claim 1, wherein in the thickness direction (Y), the length of the connecting surface (2121b) is L, and 0.1mm≤L≤0.5mm is satisfied; and / or in the thickness direction (Y), the thickness of the shell main body (211) is D1, and 0.075mm≤D1≤0.4mm is satisfied; and / or the included angle between the connecting surface (2121b) and the first wall surface (2111) is α1, and 85°≤α1≤95° is satisfied.

3. The battery according to claim 1, wherein the circular arc radius corresponding to the first arc surface (2121a) is R1, and the circular arc radius corresponding to the second arc surface (2122a) is R2, and R2<R1, 1mm≤R1≤3mm, and 0.5mm≤R2≤3mm are satisfied; and / or the included angle between the tangent line (P1) at the connecting position of the connecting surface (2121b) on the first arc surface (2121a) and the connecting surface (2121b) is α3, and α3≥0 is satisfied; and / or the connecting surface (2121b) is connected with the first wall surface (2111) and the second wall surface (2112) respectively, and the included angle between the connecting surface (2121b) and the first wall surface (2111) is α1, and the included angle between the connecting surface (2121b) and the second wall surface (2112) is α2, and 85°≤α1≤95° and 85°≤α2≤95° are satisfied. An included angle between a tangent line (P2) at a connection of the second curved surface (2122a) with the connecting surface (2121b) and the connecting surface (2121b) is α4, and α4≥0 is satisfied.

4. The battery of claim 1, wherein, The cover (22) and the connecting surface (2121b) are connected through a connecting portion (C). On a first cross section parallel to the first direction (X) and passing through the connecting portion (C), along the thickness direction (Y), the connecting portion (C) has a first point (c1) located at a connection of the cover (22) and the connecting surface (2121b) and close to the sealed cavity, and a second point (c2) away from the sealed cavity. A distance between the first point (c1) and the second point (c2) is W, a thickness of the shell body (211) is D1, and W≥0.2D1 is satisfied. And / or, the first reinforcing portion (212a) is bent towards a side close to the sealed cavity; along the thickness direction (Y), a distance between the first point (c1) and an end of the connecting surface (2121b) away from the first curved surface (2121a) is b, and b≥10μm is satisfied. And / or, the first reinforcing portion (212a) is bent towards a side away from the sealed cavity. Along the thickness direction (Y), a distance between the second point (c2) and an end of the connecting surface (2121b) close to the first curved surface (2121a) is b, and b≥10μm is satisfied. And / or, along the thickness direction (Y), a distance between the second point (c2) and the second wall surface (2112) is e, and e≤0.5D1 is satisfied.

5. The battery of any one of claims 1-4, wherein, An end of the connecting surface (2121b) away from the first curved surface (2121a) intersects with an end of the second curved surface (2122a) away from the second wall surface (2112). Or, the first reinforcing portion (212a) further comprises a first positioning surface (2123a), two ends of the first positioning surface (2123a) are connected to the end of the connecting surface (2121b) away from the first curved surface (2121a) and the end of the second curved surface (2122a) away from the second wall surface (2112) respectively.

6. The battery of claim 5, wherein, The cover (22) is provided with a protruding structure (221) protruding towards a side of the battery cell (10), and the protruding structure (221) abuts against the first positioning surface (2123a).

7. The battery of claim 6, wherein, The protruding structure (221) is continuous annular; or the protruding structure (221) is provided with a plurality of protruding structures (221), and the plurality of protruding structures (221) are discontinuous annular and spaced apart along a circumferential direction of the opening (21a); And / or, A surface of the protruding structure (221) is a curved surface; And / or, An included angle between the first positioning surface (2123a) and the connecting surface (2121b) is α2, and 80°≤α2≤120° is satisfied. And / or, In the first direction (X), a thickness of the first positioning surface (2123a) is D2, and a thickness of the shell body (211) is D1, and 0.1D1≤D2≤D1 is satisfied.

8. The battery of any one of claims 1-4, wherein, In the same projection plane perpendicular to the first direction (X), a projection of the first curved surface (2121a) is located on an inner side of a projection of the first wall surface (2111) close to the battery cell (10). And / or, In the same projection plane perpendicular to the first direction (X), a projection of the second curved surface (2122a) is located on an inner side of a projection of the second wall surface (2112) close to the battery cell (10). And / or, The first curved surface (2121a) and the second curved surface (2122a) are both convex towards an outer side away from the battery cell (10).

9. The battery of any one of claims 1-4, wherein, The accommodation space of the shell (20) is provided with an electrolyte, and the electrolyte includes ethylene carbonate, and a mass ratio A of the ethylene carbonate in the electrolyte is 5%-30%.

10. The battery of any one of claims 1-4, wherein, The shell body (21) is provided with the opening (21a) on opposite sides in the first direction (X), and the cover body (22) is provided with two, and the two cover bodies (22) are respectively connected to the shell body (21) on opposite sides in the first direction (X) and close the corresponding openings (21a); The shell body (21) further includes a second reinforcing portion (212b), and the first reinforcing portion (212a) and the second reinforcing portion (212b) are respectively connected to opposite sides of the shell body (211) in the first direction (X), and the second reinforcing portion (212b) is bent towards a side away from the sealed cavity; The first reinforcing portion (212a) is bent towards a side close to the sealed cavity.

Images