Membrane shell and battery

Abstract

The invention relates to the technical field of batteries, in particular to a membrane shell and a battery. The membrane shell is provided with a cavity, and the cavity comprises a bottom wall, a side wall arranged around the bottom wall and a ridge part connected between the bottom wall and the side wall; the edge part comprises a first arc section, a second arc section and a transition arc section in the length direction of the edge part; the section, perpendicular to the length direction of the first arc section, of the first arc section is provided with a first end point and a second end point, the first end point is connected with the bottom wall, and the second end point is connected with the side wall. A first distance is formed between the first end point and the second end point along the depth direction of the cavity; a second distance is formed between the first end point and the second end point along a preset direction, and the preset direction is respectively vertical to the depth direction of the cavity and the length direction of the edge part; the first distance is larger than the second distance. And in the circulating process of the battery, the phenomena that the battery membrane shell is sunken and the edge part close to the sunken part is upwarped to cause super-thickness are not easily caused are avoided.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a membrane housing and a battery. Background Art

[0002] Soft-pack lithium-ion batteries have been widely used in portable electronic devices and electric vehicles due to their high energy density. However, with the improvement of quality of life, while people are pursuing high ED (energy density) and long cycle life, the safety of lithium-ion batteries has also become a focus of attention.

[0003] At present, soft-pack lithium-ion batteries include a membrane shell and a battery cell. The membrane shell forms a cavity, and the battery cell is installed inside the cavity. Usually, when designing the membrane shell, a certain amount of space is reserved in the length, width and thickness directions of the cavity of the membrane shell and the battery cell.

[0004] However, when the reserved space is too large, the non-contact area between the battery cell and the membrane shell becomes larger. During the battery cycle, the side walls of the cavity are easily dented due to the atmospheric pressure, while the side walls of the cavity near the edge of the cavity are warped in the opposite direction, resulting in excessive thickness failure. Summary of the invention

[0005] Based on this, the present application provides a membrane shell and a battery to solve the problem that during the battery cycle of the related technology, the side wall of the cavity of the membrane shell is easily dented due to the atmospheric pressure, while the side wall of the cavity is warped in the opposite direction near the edge of the cavity, resulting in excessive thickness failure.

[0006] In one aspect, the present application provides a membrane shell, wherein the membrane shell is provided with a cavity, wherein the cavity comprises a bottom wall, a side wall arranged around the bottom wall, and an edge portion connected between the bottom wall and the side wall;

[0007] Along the length direction of the edge portion, the edge portion includes a first arc segment, second arc segments located at opposite ends of the first arc segment, and a transition arc segment connected between the first arc segment and the second arc segment;

[0008] The first arc segment has a first end point and a second end point on a cross section perpendicular to the length direction of the first arc segment, the first end point is connected to the bottom wall, and the second end point is connected to the side wall;

[0009] Along the depth direction of the cavity, there is a first distance between the first endpoint and the second endpoint; along a preset direction, there is a second distance between the first endpoint and the second endpoint, and the preset direction is perpendicular to the depth direction of the cavity and the length direction of the edge portion respectively;

[0010] The first distance is larger than the second distance.

[0011] In a possible implementation, the second arc segment has a third endpoint and a fourth endpoint in a cross section perpendicular to the length direction of the second arc segment, the third endpoint is connected to the bottom wall, and the fourth endpoint is connected to the side wall;

[0012] Along the depth direction of the cavity, there is a third distance between the third endpoint and the fourth endpoint; along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint;

[0013] The size of the third distance and the size of the fourth distance are both smaller than or equal to the size of the second distance.

[0014] In a possible implementation, the transition arc segment has a fifth endpoint and a sixth endpoint in a cross section perpendicular to its length direction, the fifth endpoint is connected to the bottom wall, and the sixth endpoint is connected to the side wall;

[0015] Along the depth direction of the cavity, there is a fifth distance between the fifth endpoint and the sixth endpoint; along the preset direction, there is a sixth distance between the fifth endpoint and the sixth endpoint;

[0016] The size of the fifth distance is between the size of the third distance and the size of the second distance, and the size of the sixth distance is between the size of the fourth distance and the size of the second distance.

[0017] In a possible implementation, the first arc segment is tangent to the bottom wall and the side wall respectively;

[0018] and / or,

[0019] The transition arc segments are tangent to the bottom wall and the side walls respectively;

[0020] and / or,

[0021] The second arc segment is tangent to the bottom wall and the side wall respectively.

[0022] In a possible implementation, along the length direction of the edge portion, the ratio of the length of the first arc segment to the length of the edge portion is 30%-70%; and / or,

[0023] Along the length direction of the edge, the ratio of the length of the second arc segment to the length of the edge is 5%-30%;

[0024] and / or,

[0025] Along the length direction of the edge portion, the ratio of the length of the transition arc segment to the length of the edge portion is 5%-25%.

[0026] In a possible implementation, the membrane shell includes a first shell and a second shell, and the first shell cover is arranged on the second shell;

[0027] At least one of the first shell and the second shell is provided with a cavity, and has a bottom wall, a side wall and an edge portion connected between the bottom wall and the side wall.

[0028] In a possible implementation, along the length direction of the edge portion, the second arc segments at opposite ends of the first arc segment have the same length;

[0029] And / or, along the length direction of the edge portion, the lengths of transition arc segments at two opposite ends of the first arc segment are the same.

[0030] In a possible implementation, the membrane shell includes an aluminum layer; the thickness of the aluminum layer of the membrane shell at the first arc segment position is greater than the thickness of the aluminum layer of the membrane shell at the transition arc segment position;

[0031] And / or, the membrane shell includes an aluminum layer; the thickness of the aluminum layer of the membrane shell at the transition arc segment position is greater than the thickness of the aluminum layer of the membrane shell at the second arc segment position.

[0032] In a possible implementation, the edge portion includes a first edge portion and a second edge portion, the first edge portion is located at an end of the cavity along a first direction, and the first edge portion is arranged opposite to an edge of the battery cell in the first direction;

[0033] The first edge portion and the second edge portion each include a first arc segment, a second arc segment and a transition arc segment, the second arc segment has a third endpoint and a fourth endpoint on a cross section perpendicular to its own length direction, along the depth direction of the cavity, there is a third distance between the third endpoint and the fourth endpoint; along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint; the transition arc segment has a fifth endpoint and a sixth endpoint on a cross section perpendicular to its own length direction, along the depth direction of the cavity, there is a fifth distance between the fifth endpoint and the sixth endpoint; along the preset direction, there is a sixth distance between the fifth endpoint and the sixth endpoint;

[0034] On the first edge, the first distance is 1.2 mm to 3 mm; and / or,

[0035] On the first edge, the second distance is 0.4 mm to 1.2 mm; and / or,

[0036] On the first edge portion, the third distance is 0.4 mm to 1.2 mm; and / or,

[0037] On the first edge, the fourth distance is 0.4 mm to 1.2 mm; and / or,

[0038] On the first edge portion, the size of the fifth distance is 0.4 mm-1.2 mm; and / or,

[0039] On the first edge portion, a dimension of the sixth distance is 0.4 mm-1.2 mm.

[0040] In a possible implementation, the battery cell includes a bending section, the bending section of the battery cell is located on two opposite sides of the battery cell in the second direction, and the second edge portion located on either side of the membrane shell in the second direction is arranged opposite to the bending section on two opposite sides of the battery cell in the second direction;

[0041] On the second edge portion, the dimension of the first distance is a2, and a2 satisfies: T / 2+B≤a2≤T, 0.5mm≤B≤2T / 5, where T is the thickness of the battery cell; and / or,

[0042] On the second edge portion, the size of the second distance is b2, b2 satisfies: T / 2-A≤b2≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery cell; and / or,

[0043] On the second edge portion, the dimension of the third distance is r3, r3 satisfies: T / 2-A≤r3≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery cell; and / or,

[0044] On the second edge portion, the size of the fourth distance is r4, r4 satisfies: T / 2-A≤r4≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery cell; and / or,

[0045] On the second edge portion, the size of the fifth distance is R3, R3 satisfies: T / 2-A≤R3≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery cell; and / or,

[0046] On the second edge portion, the dimension of the sixth distance is R4, and R4 satisfies: T / 2-A≤R4≤T / 2, 0.5mm≤A≤2T / 5, where T is the thickness of the battery cell.

[0047] In a possible implementation, the battery cell is a laminated battery cell, and the second edge portion is arranged opposite to an edge of the battery cell in the second direction;

[0048] On the second edge portion, the first distance is 1.2 mm to 3 mm; and / or,

[0049] On the second edge portion, the second distance is 0.4 mm to 1.2 mm; and / or,

[0050] On the second edge portion, the third distance is 0.4 mm to 1.2 mm; and / or,

[0051] On the second edge portion, the fourth distance is 0.4 mm to 1.2 mm; and / or,

[0052] On the second edge portion, the size of the fifth distance is 0.4 mm-1.2 mm; and / or,

[0053] On the second edge portion, the sixth distance is 0.4 mm-1.2 mm.

[0054] In a possible implementation, the size of the third distance on the same second arc segment is equal to the size of the fourth distance; and / or,

[0055] The size of the fifth distance on the same transition arc segment is equal to the size of the sixth distance.

[0056] The membrane shell and battery provided in the present application are provided with a cavity, through which a battery cell can be accommodated. The cavity includes a bottom wall, a side wall arranged around the bottom wall, and an edge connected between the bottom wall and the side wall. That is to say, the bottom wall and the side wall of the cavity are connected by an edge. Along the length direction of the edge, the edge includes a first arc segment, a second arc segment located at opposite ends of the first arc segment, and a transition arc segment connected between the first arc segment and the second arc segment. There is a first distance between the two end points on the cross section of the first arc segment in the depth direction of the cavity, and there is a second distance between the two end points on the cross section of the first arc segment in a preset direction, and the preset direction is respectively perpendicular to the depth direction of the cavity and the length direction of the edge. The size of the first distance is greater than the size of the second distance. The first arc segment arranged in this way is closer to one end of the battery cell facing the side wall of the cavity than the arc segment with the first distance equal to the second distance. The first arc segment can better fit the battery cell, and the risk of over-thickness failure caused by the depression of the battery membrane shell and the tilting of the edge near the depression is not easy to occur during the battery cycle, so that the battery is not easy to be over-thick. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 It is a structural schematic diagram of a membrane shell in the related art;

[0059] Figure 2 Schematic diagram of the structure of the membrane shell before packaging provided in the embodiment of the present application Figure 1 ;

[0060] Figure 3 Schematic diagram of the structure of the membrane shell before packaging provided in the embodiment of the present application Figure 2 ;

[0061] Figure 4 Schematic diagram of the structure of the membrane shell before packaging provided in the embodiment of the present application Figure 3 ;

[0062] Figure 5 Schematic diagram of the structure of the membrane shell before packaging provided in the embodiment of the present application Figure 4 ;

[0063] Figure 6 Schematic diagram of the structure of the membrane shell provided in the embodiment of the present application Figure 1 ;

[0064] Figure 7 A schematic diagram of a membrane shell provided in an embodiment of the present application at one of its edges;

[0065] Figure 8 A schematic diagram of a membrane shell provided in an embodiment of the present application at a first arc segment position;

[0066] Fig. 9 A schematic diagram of a membrane shell provided in an embodiment of the present application at a second arc segment position;

[0067] Fig.10 Schematic diagram of the structure of the membrane shell provided in the embodiment of the present application Figure 2 ;

[0068] Fig.11 A schematic diagram of a membrane shell provided in an embodiment of the present application at another edge position;

[0069] Fig.12 A schematic diagram of the membrane shell provided in an embodiment of the present application at the edge position;

[0070] Fig.13 A schematic diagram of the structure of the male mold provided in an embodiment of the present application.

[0071] Description of reference numerals:

[0072] 100-first housing;

[0073] 200- second housing;

[0074] 300-Cavity;

[0075] 410 - bottom wall; 420 - side wall; 430 - edge; 431 - first arc segment; 432 - second arc segment; 433 - transition arc segment; 434 - first edge; 435 - second edge; 401 - edge;

[0076] 500 - punch; 510 - bottom surface; 520 - side surface; 530 - arc surface; 531 - first arc surface; 532 - second arc surface; 533 - transition arc surface. DETAILED DESCRIPTION

[0077] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0078] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0079] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0080] The terms "first", "second" and "third" (if any) in the specification and claims of this application and the above drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0081] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display comprising a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0082] In the prior art, such as Figure 1As shown, the soft-pack lithium-ion battery includes a membrane shell made of aluminum-plastic film and a battery cell, the membrane shell forms a cavity, and the battery cell is installed inside the cavity. The cavity is generally formed by punching, and the bottom wall and the side wall of the cavity are connected by an arc edge 401 of a single radius. Usually, when designing the membrane shell, a certain amount of space is reserved in the length, width and thickness directions of the cavity of the membrane shell and the battery cell. However, when the reserved space is too large, the area without contact between the battery cell and the membrane shell becomes larger. Then, during the battery cycle, the side wall of the cavity is easily concave due to the atmospheric pressure, and the side wall of the cavity is tilted in the opposite direction near the edge of the cavity, resulting in over-thickness failure.

[0083] Although the use of fixtures and other components to shape the sides of the battery membrane shell can improve the bulging of the battery membrane shell edges, the improvement effect on battery expansion is limited, and it is easy to damage the pole pieces of the battery cells inside the cavity, damage the membrane shell, and cause problems with the appearance of the battery. In addition, after a period of shaping, the edges are prone to rebound and bulge again, causing cyclic thickness expansion failure.

[0084] At present, the side edge (bend section) of the wound battery is actually an arc surface that is close to a perfect circle (not a perfect circle), so the arc surface design of the transition surface cannot perfectly fit the battery cell. In order to reduce the risk of corner cracks in long-term battery cycles, a certain amount of space is usually reserved in the length, width and thickness directions of the membrane shell and the battery when designing the membrane shell. When the reserved space is too large, the reserved space between the end of the battery cell facing the side wall of the cavity and the side wall of the cavity causes the side wall of the cavity to have no effective support. Under the action of atmospheric pressure, the side wall of the cavity will be concave close to the battery cell, and the edge of the membrane shell close to the concave part will be tilted in the opposite direction, resulting in excessive thickness failure.

[0085] After repeated thinking and verification, the inventor found that if the shape of the edge of the cavity is changed, the arc shape in the middle of the edge can better fit the battery cell in the cavity. In this way, the middle of the edge can better fit the battery cell, and the battery is less likely to have the risk of over-thickness failure caused by the depression of the battery membrane shell and the warping of the edge near the depression during the cycle, making the battery less likely to be over-thick.

[0086] In view of this, the inventor has designed a membrane shell and a battery, in which the bottom wall and the side wall of the cavity of the membrane shell are connected by an edge, the middle of the edge is set as a first arc segment, the two ends of the edge are set as second arc segments, and the first arc segment and the second arc segment are transitioned by a transition arc segment. In the depth direction of the cavity, the first arc segment has a first distance between the two endpoints on the cross section perpendicular to its own length direction; in the direction perpendicular to the depth direction of the cavity and the length direction of the edge respectively, the first arc segment has a second distance between the two endpoints on the cross section perpendicular to its own length direction, and the size of the first distance is greater than the size of the second distance. The first arc segment in the middle of the edge is more closely fitted to the battery cell in the cavity, and the risk of over-thickness failure caused by the depression of the battery membrane shell and the warping of the edge near the depression is not likely to occur during the battery cycle.

[0087] The technical solutions of the membrane housing and the battery provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0088] Reference Figures 2 to 8 As shown, the membrane shell provided in the embodiment of the present application is provided with a cavity 300. The cavity 300 of the membrane shell can be used to accommodate the battery cell. The material of the membrane shell can be an aluminum-plastic film, and the aluminum-plastic film can be stamped using a convex mold to form the cavity 300 on the membrane shell.

[0089] The cavity 300 includes a bottom wall 410, a side wall 420 disposed around the bottom wall 410, and an edge portion 430 connected between the bottom wall 410 and the side wall 420. Exemplarily, the cavity 300 includes a bottom wall 410 and four side walls 420 disposed around the bottom wall 410. After the membrane shell forms the cavity 300, the membrane shell also has an opening connected to the cavity 300, and the bottom wall 410 of the cavity 300 is disposed away from the opening. The edge portion 430 of the membrane shell forms an edge of the cavity 300 away from the opening.

[0090] In a possible implementation, each side wall 420 is connected to the bottom wall 410 via an edge portion 430, that is, the number of the edges 430 may be the same as the number of the side walls 420. In another possible implementation, some side walls 420 are connected to the bottom wall 410 via an edge portion 430, that is, the number of the edges 430 may be less than the number of the side walls 420. For example, when the cavity 300 has four side walls 420, the number of the edges 430 may be one, two, or three.

[0091] Along the length direction of the ridge 430, the ridge 430 includes a first arc segment 431, second arc segments 432 respectively located at opposite ends of the first arc segment 431, and a transition arc segment 433 connected between the first arc segment 431 and the second arc segment 432. Among them, the number of the second arc segments 432 and the number of the transition arc segments 433 are both two, the two second arc segments 432 are respectively located at the two ends of the ridge 430, and each transition arc segment 433 is connected between the first arc segment 431 and the corresponding second arc segment 432. Exemplarily, the cross section of the second arc segment 432 and the cross section of the transition arc segment 433 can be circular arcs, and the curvature of the cross section of the second arc segment 432 is consistent at all places, and the curvature of the cross section of the transition arc segment 433 is consistent at all places. It can be understood that the end of the second arc segment 432 away from the first arc segment 431 is used to define the angular position of the membrane shell.

[0092] The first arc segment 431 has a first endpoint and a second endpoint on a cross section perpendicular to its length direction, the first endpoint is connected to the bottom wall 410, and the second endpoint is connected to the side wall 420. It can be understood that the first endpoint is the connection point between the first arc segment 431 and the bottom wall 410, and the second endpoint is the connection point between the first arc segment 431 and the side wall 420. Exemplarily, the membrane shell can be cut to obtain a cross section of the first arc segment 431, and the position and distance of the first endpoint and the second endpoint in the above cross section can be obtained by a profile measuring instrument. Of course, in some other ways, the contour curves of different arc segments on the membrane shell can also be directly scanned and points can be obtained by a laser sensor on the profile measuring instrument to obtain the position and distance of the two endpoints of different arc segments.

[0093] Along the depth direction of the cavity 300, there is a first distance between the first end point and the second end point. Along a preset direction, there is a second distance between the first end point and the second end point, and the preset direction is perpendicular to the depth direction of the cavity 300 and the length direction of the edge 430. The depth direction of the cavity 300 is Figure 7 The direction of the Q axis is the preset direction. Figure 7 The preset direction can be set according to the length direction of the cut edge portion 430, for example, Figure 4 and Figure 5 The longer edge 430 is preset in the direction Figure 4 and Figure 5 The direction of the Y axis is Figure 4 and Figure 5 The shorter edge 430 is in the preset direction Figure 4 and Figure 5 The first distance is the space occupied by the cross section of the first arc segment 431 in the depth direction of the cavity 300, and the second distance is the space occupied by the cross section of the first arc segment 431 in the preset direction.

[0094] The size of the first distance is greater than the size of the second distance. Exemplarily, a profilometer can be used to obtain the size of the first distance and the size of the second distance. Specifically, the membrane shell can be cut to obtain the cross section of the first arc segment 431, and the membrane shell to be measured with the cross section of the first arc segment 431 is placed on the profilometer measurement platform; the laser sensor of the profilometer scans the membrane shell to obtain points, obtains the contour diagram and size data of the membrane shell, and then obtains the size of the first distance and the size of the second distance.

[0095] like Figure 8 As shown, the cross sections of the first arc segment 431 along its length are consistent.

[0096] In a possible implementation, the cross section of the first arc segment 431 in the direction perpendicular to the length of the edge 430 is an elliptical arc, the major axis of the elliptical arc is parallel to the depth direction of the cavity 300, and the minor axis of the elliptical arc is parallel to the preset direction. In a possible implementation, the cross section of the first arc segment 431 in the direction perpendicular to the length of the edge 430 is a circular arc, and the distance between the center of the circular arc and the side wall 420 is greater than the distance between the center of the circular arc and the bottom wall 410.

[0097] Those skilled in the art will appreciate that the membrane shell can be formed by punching the membrane shell material through a convex die. Fig.13 As shown, the punch 500 includes a bottom surface 510, a side surface 520, and a curved surface 530 connected between the bottom surface 510 and the side surface 520. The structure of the first edge portion 434 matches the curved surface 530, that is, the curved surface 530 includes a first curved surface 531, a second curved surface 532 located at opposite ends of the first curved surface 531, and a transition curved surface 533 connected between the first curved surface 531 and the second curved surface 532, the first curved surface 531 forms a first arc segment 431, the second curved surface 532 forms a second arc segment 432, and the transition curved surface 533 forms a transition arc segment 433. Along the stamping direction of the punch 500, the first curved surface 531 has two endpoints in a cross section perpendicular to its own length direction, one of which is connected to the bottom surface 510, and the other is connected to the side surface 520. There is a first interval between the two endpoints along the punching direction of the punch 500 and a second interval between the two endpoints along a predefined direction, the predefined direction being perpendicular to the punching direction of the punch 500 and the extending direction of the arc surface 530. The first interval is greater than the second interval.

[0098] The membrane shell provided in this embodiment has a bottom wall 410 and a side wall 420 of the cavity 300 connected by an edge 430. Along the length direction of the edge 430, the edge 430 includes a first arc segment 431, a second arc segment 432 located at opposite ends of the first arc segment 431, and a transition arc segment 433 connected between the first arc segment 431 and the second arc segment 432. There is a first distance between the two end points on the cross section of the first arc segment 431 in the depth direction of the cavity 300, and there is a second distance between the two end points on the cross section of the first arc segment 431 in a preset direction, and the preset direction is respectively perpendicular to the depth direction of the cavity 300 and the length direction of the edge 430. The size of the first distance is greater than the size of the second distance. The first arc segment 431 configured in this way is closer to the end of the battery cell facing the side wall 420 of the cavity 300 than the arc segment in which the first distance is equal to the second distance. The first arc segment 431 can better fit the battery cell, and the risk of over-thickness failure caused by the depression of the battery membrane shell and the warping of the edge 430 near the depressed part is not likely to occur during the battery cycle, so that the battery is not prone to being over-thick.

[0099] In one embodiment, Figure 2-Figure 9 As shown, the second arc segment 432 has a third endpoint and a fourth endpoint in a cross section perpendicular to its length direction, the third endpoint is connected to the bottom wall 410, and the fourth endpoint is connected to the side wall 420. It can be understood that the third endpoint is the connection point between the second arc segment 432 and the bottom wall 410, and the fourth endpoint is the connection point between the second arc segment 432 and the side wall 420. Exemplarily, the membrane shell can be cut to obtain a cross section of the second arc segment 432, and the positions of the third endpoint and the fourth endpoint in the cross section can be obtained by a profilometer.

[0100] Along the depth direction of the cavity 300, there is a third distance between the third endpoint and the fourth endpoint. Along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint. The third distance is the space occupied by the cross section of the second arc segment 432 in the depth direction of the cavity 300, and the fourth distance is the space occupied by the cross section of the second arc segment 432 in the preset direction. The present embodiment does not limit the size relationship between the size of the third distance and the size of the fourth distance, and those skilled in the art can set it as needed. Figure 8 As shown, the cross sections of the second arc segment 432 are consistent at various locations along its length.

[0101] The size of the third distance and the size of the fourth distance are both smaller than or equal to the size of the second distance.

[0102] When the battery cell is placed in the cavity 300 of the membrane shell, since the size of the first distance is greater than the size of the second distance, and the sizes of the third distance and the fourth distance are both less than or equal to the size of the second distance, the gap between the battery cell and the first arc segment 431 is smaller than the gap between the battery cell and the second arc segment 432. It can be understood by those skilled in the art that the end of the edge portion 430 can define the angular position of the cavity 300, and the end of the second arc segment 432 away from the first arc segment 431 can ensure the reserved space between the cavity 300 and the battery cell at the angular position.

[0103] In the related art, the bottom wall 410 and the side wall 420 of the cavity 300 are connected by an arc-shaped edge with a single radius. If a small reserved space is set between the cavity 300 of the membrane shell and the battery cell, the battery cell will expand during a long cycle of the battery, and the aluminum-plastic film will be repeatedly squeezed and stretched, which may easily cause corner cracks at the corners of the cavity 300. The membrane shell provided in this embodiment has an edge 430 that is combined with arc segments of different radii, which can reduce the redundancy of the aluminum-plastic film on each transition surface. While the battery is not easy to be over-thick due to the tilting of the edge 430 of the membrane shell, the second arc segment 432 can make the corner of the cavity 300 have a larger space between the battery cell, and the membrane shell is not easy to crack during a long cycle of the battery, which increases the number of cycles that the battery can be circulated.

[0104] In a specific embodiment, Figure 2-Figure 7 As shown, the transition arc segment 433 has a fifth endpoint and a sixth endpoint on a cross section perpendicular to its own length direction, the fifth endpoint is connected to the bottom wall 410, and the sixth endpoint is connected to the side wall 420. The fifth endpoint is the connection point between the cross section perpendicular to the length direction of the transition arc segment 433 and the bottom wall 410, and the sixth endpoint is the connection point between the cross section perpendicular to the length direction of the transition arc segment 433 and the side wall 420. Exemplarily, the transition arc segment 433 of the membrane shell can be cut at the position to obtain the cross section of the transition arc segment 433, and the positions of the fifth endpoint and the sixth endpoint in the above cross section can be obtained by a profilometer.

[0105] There is a fifth distance between the fifth endpoint and the sixth endpoint along the depth direction of the cavity 300. There is a sixth distance between the fifth endpoint and the sixth endpoint along the preset direction. The fifth distance is the space occupied by the cross section of the transition arc segment 433 in the depth direction of the cavity 300, and the sixth distance is the space occupied by the cross section of the transition arc segment 433 in the preset direction.

[0106] The size of the fifth distance is between the size of the third distance and the size of the second distance, and the size of the sixth distance is between the size of the fourth distance and the size of the second distance.

[0107] When the size of the third distance and the size of the fourth distance are respectively smaller than the size of the second distance, the size of the fifth distance and the size of the sixth distance both increase in the direction from the second arc segment 432 to the first arc segment 431. The size of the fifth distance and the size of the sixth distance can be obtained by a profilometer. At one end of the transition arc segment 433 toward the second arc segment 432, the fifth distance can be equal to the third distance, and the sixth distance can be equal to the fourth distance. At one end of the transition arc segment 433 toward the second arc segment 432, the fifth distance and the sixth distance can be equal to the second distance, respectively.

[0108] Through the above arrangement, the edge portion 430 gradually transitions between the first arc segment 431 and the second arc segment 432 , and wrinkles are less likely to appear on the membrane shell at the edge portion 430 , which is beneficial to ensuring the overall structural strength of the membrane shell.

[0109] like Figure 2-Figure 5 As shown, the membrane shell includes a first shell 100 and a second shell 200, and the first shell 100 is covered on the second shell 200. Among them, the first shell 100 and the second shell 200 can be sheet structures respectively. After the first shell 100 is covered on the second shell 200, it can be fixed by bonding or thermal packaging. In a possible implementation, the first shell 100 and the second shell 200 can be connected to each other, for example, the middle part of the aluminum-plastic film can be bent, and the parts of the aluminum-plastic film on both sides of the bending area respectively define the first shell 100 and the second shell 200. In another possible implementation, the first shell 100 and the second shell 200 can also be a split structure, that is, the first shell 100 is not connected to the second shell 200 before being covered on the second shell 200.

[0110] At least one of the first shell 100 and the second shell 200 is provided with a cavity 300, and has a bottom wall 410, a side wall 420, and an edge 430 connected between the bottom wall 410 and the side wall 420. Specifically, only the first shell 100 can be punched to form the cavity 300, or only the second shell 200 can be punched to form the cavity 300, or the first shell 100 and the second shell 200 can be punched separately, so as to form the cavity 300 on the first shell 100 and the second shell 200 respectively. When the first shell 100 and the second shell 200 are respectively provided with the cavity 300, after the first shell 100 is covered on the second shell 200, the cavity 300 on the first shell 100 and the cavity 300 on the second shell 200 are located opposite to each other. That is to say, the membrane shell can be a single-pit membrane shell or a double-pit membrane shell. When the first housing 100 is provided with a cavity 300, the cavity 300 has at least one ridge 430; when the second housing 200 is provided with a cavity 300, the cavity 300 has at least one ridge 430. That is, the bottom wall 410 and the side wall 420 of the cavity 300 are transitioned through the ridge 430, and the ridge 430 includes a first arc segment 431, transition arc segments 433 located on both sides of the first arc segment 431, and a second arc segment 432 located on the side of the two transition arc segments 433 away from the first arc segment 431.

[0111] Through the above arrangement, the structure of the membrane shell is more diverse, and can be specifically arranged according to the battery cells to be accommodated. During the battery cycle, the battery membrane shell is not prone to depression and the edge portion 430 near the depression is not prone to tilting, resulting in excessive thickness.

[0112] In a specific embodiment, Figure 7 and Figure 8 As shown, the first arc segment 431 is tangent to the bottom wall 410 and the side wall 420 respectively. Figure 8 As shown, the cross section of the first arc segment 431 is an elliptical arc, L1 and L2 are two tangents of the elliptical arc, the extension direction of L1 is parallel to the bottom wall 410, and the extension direction of L2 is parallel to the side wall 420. The perpendicular line T1 corresponding to L1 and the perpendicular line T2 corresponding to L2 are compared to point P. The major semi-axis of the elliptical arc is a, the minor semi-axis of the elliptical arc is b, and the two foci F1 and F2 of the elliptical arc are located on the straight line where the major semi-axis a is located, and the focal length of the two foci is 2c, and a satisfies 2 =b 2 +c 2 The first distance is equal to the length of the minor semi-axis of the ellipse arc, and the second distance is equal to the length of the major semi-axis of the ellipse arc.

[0113] like Figure 7As shown, the transition arc segment 433 is tangent to the bottom wall 410 and the side wall 420. Exemplarily, the cross section of the transition arc segment 433 is an arc, and the size of the fifth distance and the size of the sixth distance are both equal to the radius of the arc.

[0114] like Figure 7 and Fig. 9 As shown, the second arc segment 432 is tangent to the bottom wall 410 and the side wall 420 respectively. Exemplarily, the cross section of the second arc segment 432 is an arc, and the size of the third distance and the size of the fourth distance are both equal to the radius of the arc. Fig. 9 As shown, L3 and L4 are two tangent lines of the arc of the cross section of the second arc segment 432, the extension direction of L3 is parallel to the bottom wall 410, and the extension direction of L4 is parallel to the side wall 420. The vertical line T3 corresponding to L3 and the vertical line T4 corresponding to L4 are compared to point O.

[0115] Through the above arrangement, the arc segments of the edge 430 are tangent to the bottom wall 410 and the side wall 420, respectively, so that no obvious edges appear between the arc segments of the edge 430 and the bottom wall 410 and the side wall 420, respectively, thereby ensuring the appearance of the battery and preventing wrinkles from easily appearing on the membrane shell at the edge 430.

[0116] In a specific embodiment, Figure 7 and Fig.11 As shown, along the length direction of the edge 430, the ratio of the length of the first arc segment 431 (H1 or W1) to the length of the edge 430 is 30%-70%. For example, the ratio of the length of the first arc segment 431 to the length of the edge 430 can be 30%, 40%, 50%, 60%, 70% or a range consisting of any two thereof, which is not limited here.

[0117] When the ratio of the length of the first arc segment 431 to the length of the ridge 430 is less than 30%, it indicates that the length of the portion with a small gap space between the middle of the ridge 430 and the battery cell is small, and the improvement effect on the depression of the membrane shell and the warping of the ridge 430 caused by the depression is small, and the depression of the membrane shell and the warping of the ridge 430 near the depression may cause over-thickness; when the ratio of the length of the first arc segment 431 to the length of the ridge 430 is greater than 70%, the length of the transition arc segment 433 and the second arc segment 432 will be small, so that the battery may have corner cracks and wrinkles in the membrane shell during a long cycle. That is to say, by controlling the ratio between the length of the first arc segment 431 and the length of the ridge 430, it is possible to make the membrane shell less likely to be depressed, the battery less likely to be over-thick, and the membrane shell less likely to have corner cracks or wrinkles. Preferably, the length of the first arc segment 431 accounts for 30%-60% of the length of the ridge 430. The above arrangement makes it less likely that the edges will be dented, and the corners of the battery will be less likely to crack, and the membrane shell will not be wrinkled.

[0118] Indicatively, Figure 7 and Fig.11 As shown, along the length direction of the edge 430, the ratio of the length of the second arc segment 432 (H1, H5, W1 or W5) to the length of the edge 430 is 5%-30%. For example, the ratio of the length of the second arc segment 432 to the length of the edge 430 can be 5%, 10%, 15%, 20%, 25%, 30% or a range consisting of any two thereof, which is not limited here.

[0119] When the ratio of the length of the second arc segment 432 to the length of the edge 430 is less than 5%, it indicates that the length of the portion with a larger space between the end of the edge 430 and the battery cell is smaller, and the battery may crack during a long cycle; when the ratio of the length of the second arc segment 432 to the length of the edge 430 is greater than 30%, the lengths of the transition arc segment 433 and the first arc segment 431 are smaller, and the improvement effect on the membrane shell depression and the tilting of the edge 430 caused by the depression is smaller. In other words, by setting the ratio between the length of the second arc segment 432 and the length of the edge 430, the battery is not prone to cracking during a long cycle, and the battery is not prone to being too thick. Preferably, the length of the second arc segment 432 accounts for 10%-25% of the length of the edge 430, and the battery is less likely to crack during a long cycle, and the membrane shell is not prone to depression, resulting in an over-thick battery.

[0120] Indicatively, Figure 7 and Fig.11 As shown, along the length direction of the edge 430, the ratio of the length of the transition arc segment 433 (H2, H4, W2 or W4) to the length of the edge 430 is 5%-25%. For example, the ratio of the length of the transition arc segment 433 to the length of the edge 430 can be 5%, 10%, 15%, 20%, 25%, or a range consisting of any two thereof, which is not limited here.

[0121] When the ratio between the length of the transition arc segment 433 and the length of the edge 430 is less than 5%, the length of the transition arc segment 433 accounts for too small a proportion, the transition angle between the first arc segment 431 and the second arc segment 432 is sharp, and the membrane shell is prone to wrinkles; when the ratio between the length of the transition arc segment 433 and the length of the edge 430 is greater than 25%, the length of the transition arc segment 433 accounts for too large a proportion, affecting the length proportion of the first arc segment 431 and / or the second arc segment 432, so that the battery may have corner cracks and / or be too thick. The above-mentioned setting can ensure the length proportion of the first arc segment 431 and / or the second arc segment 432, so that the membrane shell of the battery is not prone to depression and the edge 430 caused by the depression is tilted to cause the battery to be too thick, and wrinkles are not easy to appear on the membrane shell. Preferably, the length of the transition arc segment 433 accounts for 8%-22% of the length of the edge 430, and the battery is less likely to have problems of overthickness or corner cracks.

[0122] In one embodiment, Fig.10 As shown, along the length direction of the edge portion 430 , the second arc segments 432 at opposite ends of the first arc segment 431 have the same length.

[0123] Specifically, the lengths of the two second arc segments 432 of the edge 430 are the same, that is, W1=W5, H1=H5. It can be understood by those skilled in the art that during the cycle of the battery, the battery cells expand synchronously at the edge 401. The above arrangement can make the squeezing force of the battery cells on the two second arc segments 432 of the edge 430 consistent, which is conducive to ensuring the structural integrity and electrochemical performance of the battery. In addition, the above arrangement is conducive to making the two corners of the membrane shell on both sides of the first arc segment 431 less likely to be damaged (corner cracks).

[0124] In one embodiment, Fig.10 As shown, along the length direction of the edge 430, the transition arc segments 433 at the two opposite ends of the first arc segment 431 have the same length. That is, W2 = W4, H2 = H4. The above arrangement can make the two transition arc segments 433 of the edge 430 receive the same extrusion force from the battery cell, which is conducive to ensuring the structural integrity and electrochemical performance of the battery.

[0125] In a possible implementation, the two second arc segments 432 of the edge 430 have the same length, and the two transition arc segments 433 of the edge 430 have the same length. The above arrangement allows the first arc segment 431 of the edge 430 to be located in the middle of the edge 430, which is conducive to reliably avoiding the membrane shell from sinking.

[0126] In one embodiment, the film shell includes an aluminum layer, specifically, the film shell material (aluminum-plastic film) includes an aluminum layer, a protective layer such as a nylon layer located on one side of the aluminum layer, and a heat-sealing layer such as a PP layer located on the other side of the aluminum layer. After the film shell material is punched, the aluminum layer of the punched area of ​​the film shell material will be extended.

[0127] The thickness of the aluminum layer of the membrane shell at the first arc segment 431 is greater than the thickness of the aluminum layer of the membrane shell at the transition arc segment 433. Specifically, after the membrane shell material is stamped, the degree of ductility of the aluminum layer of the membrane shell at the transition arc segment 433 is greater than the degree of ductility of the aluminum layer of the membrane shell material at the first arc segment 431. The greater the degree of ductility of the aluminum layer, the smaller its thickness, and thus the thickness of the aluminum layer of the membrane shell at the first arc segment 431 is greater than the thickness of the aluminum layer of the membrane shell at the transition arc segment 433. The membrane shell can be cut at the first arc segment 431 and the transition arc segment 433 to obtain the cross section of the membrane shell at the first arc segment 431 and the cross section of the transition arc segment 433, and the thickness of the aluminum layer of the membrane shell at the first arc segment 431 and the transition arc segment 433 is obtained by a 3D microscope.

[0128] Exemplarily, when the thickness of the aluminum-plastic film is 70 μm-120 μm, the thickness of the aluminum layer of the film shell material at the first arc segment 431 may be 35 μm-40 μm, and the thickness of the aluminum layer of the film shell material at the transition arc segment 433 may be 30 μm-35 μm.

[0129] Those skilled in the art can understand that the deformation of the membrane shell material at the transition arc segment 433 is larger than the deformation at the first arc segment 431, and the edge 430 at the first arc segment 431 can fit the battery cell more closely, so that the membrane shell is not easily concave during the battery cycle, and the edge 430 of the membrane shell near the concave position is not easy to warp up, causing the battery to be too thick.

[0130] In one embodiment, the membrane shell includes an aluminum layer, and the thickness of the aluminum layer of the membrane shell at the transition arc segment 433 is greater than the thickness of the aluminum layer of the membrane shell at the second arc segment 432 .

[0131] That is to say, the extension degree of the aluminum layer of the membrane shell at the second arc segment 432 is greater than the extension degree of the aluminum layer of the membrane shell at the transition arc segment 433, and the deformation amount of the aluminum layer of the membrane shell at the second arc segment 432 is greater than the deformation amount of the aluminum layer of the membrane shell at the transition arc segment 433.

[0132] Exemplarily, when the thickness of the aluminum-plastic film is 70 μm-120 μm, the thickness of the aluminum layer of the film shell material at the transition arc segment 433 may be 30 μm-35 μm, and the thickness of the aluminum layer of the film shell material at the second arc segment 432 may be 25 μm-30 μm.

[0133] It can be understood by those skilled in the art that the deformation of the membrane shell material at the transition arc segment 433 is smaller than the deformation at the second arc segment 432, so that there is a larger space between the corner of the cavity 300 and the battery cell, and the membrane shell of the battery is not prone to corner cracks during long cycles.

[0134] The present application also provides a battery, comprising a battery cell and the above-mentioned membrane shell, wherein the battery cell is arranged in the cavity 300 of the membrane shell.

[0135] The battery cell may be a laminated battery cell or a wound battery cell. After the battery cell is placed in the cavity 300 of the membrane shell, a battery is formed by sequentially performing processes such as liquid injection and packaging.

[0136] The battery provided in the present application adopts the above-mentioned membrane shell, so the membrane shell is not easily sunken during the cycle of the battery, and the edge 430 near the sunken part is not easily lifted up to cause excessive thickness, and the energy density of the battery can be guaranteed.

[0137] In one embodiment, Figure 6 , Figure 7 , Fig.10 and Fig.11 As shown, the edge portion 430 includes a first edge portion 434 and a second edge portion 435. The first edge portion 434 is located at the end of the cavity 300 along the first direction, and the first edge portion 434 is arranged opposite to the edge of the battery cell in the first direction. Among them, the extension direction of the pole ear of the battery cell in the cavity 300 is parallel to the first direction, that is, the pole ear of the battery cell extends out of the cavity 300 along the first direction. The second direction is perpendicular to the first direction. Exemplarily, the first direction is the direction indicated by the X-axis, that is, the length direction of the cavity 300. The second direction is the direction indicated by the Y-axis, that is, the width direction of the cavity 300. As shown Figure 6 and Fig.10 As shown, the cavity 300 may have two first edges 434 and two second edges 435 , wherein the two first edges 434 are disposed opposite to each other along a first direction, and the two second edges 435 are disposed opposite to each other along a second direction.

[0138] The first edge portion 434 and the second edge portion 435 each include a first arc segment 431, a second arc segment 432 and a transition arc segment 433. The second arc segment 432 has a third endpoint and a fourth endpoint in a cross section perpendicular to its length direction. Along the depth direction of the cavity 300, there is a third distance between the third endpoint and the fourth endpoint; along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint; the transition arc segment 433 has a fifth endpoint and a sixth endpoint in a cross section perpendicular to its length direction. Along the depth direction of the cavity 300, there is a fifth distance between the fifth endpoint and the sixth endpoint; along the preset direction, there is a sixth distance between the fifth endpoint and the sixth endpoint;

[0139] like Fig.11 As shown, the size a1 of the first distance is 1.2 mm-3 mm. For example, the size of a1 can be 1.2 mm, 1.5 mm, 1.8 mm, 2.2 mm, 2.5 mm, 2.8 mm or 3 mm, etc., which is not limited here.

[0140] When the dimension a1 of the first distance is greater than 3mm, the first arc segment 431 of the first edge 434 may interfere with the battery cell, affecting the battery cell's entry into the shell; when the dimension a1 of the first distance is less than 1.2mm, the gap between the first arc segment 431 of the first edge 434 and the battery cell is large, and the membrane shell may be dented, causing the edge 430 to tilt. By setting the dimension of the first distance, the battery cell can be smoothly inserted into the shell and the membrane shell is not prone to being dented, causing the edge 430 to tilt and make the battery too thick. Preferably, 1.5mm≤a1≤2.5mm, which further facilitates the insertion of the battery cell into the shell while preventing the battery from being too thick.

[0141] like Fig.11As shown, on the first edge portion 434, the size b1 of the second distance is 0.4 mm-1.2 mm. For example, the size of b1 can be 0.4 mm, 0.6 mm, 0.8 mm, 1 mm or 1.2 mm, etc., which is not limited here.

[0142] When the size b1 of the second distance is greater than 1.2mm, the first arc segment 431 of the first edge 434 may interfere with the battery cell, affecting the battery cell's entry into the shell; when the size b1 of the second distance is less than 0.4mm, the gap between the first arc segment 431 of the first edge 434 and the battery cell is large, and the membrane shell may be dented, causing the edge 430 to tilt. In other words, by setting the size b1 of the second distance of the first edge 434, the battery cell can be smoothly inserted into the shell and the membrane shell is not likely to be dented, causing the edge 430 to tilt and make the battery too thick. Preferably, 0.6mm≤b1≤1.0mm, which further facilitates the insertion of the battery cell into the shell while preventing the battery from being too thick.

[0143] like Fig.11 As shown, on the first edge 434, the dimension r1 of the third distance is 0.4mm-1.2mm. That is, 0.4mm≤r1≤1.2mm. The size of r1 can be 0.4mm, 0.6mm, 0.8mm or 1.2mm, etc., and is not limited here. When r1<0.4mm, the arc radius of the second arc segment 432 of the first edge 434 is small. During the process of processing the cavity 300 by stamping, the membrane shell is prone to damage at the position of the second arc segment 432 of the first edge 434; when r1>1.2mm, the gap between the second arc segment 432 of the first edge 434 and the battery cell is small, and the battery may crack at the corner. In other words, through the above-mentioned setting, the second arc segment 432 of the first edge 434 can be prevented from being damaged during the processing, and the battery is not prone to crack at the corner. Preferably, 0.6 mm ≤ r1 ≤ 1.0 mm, which further prevents the second arc segment 432 of the first edge portion 434 from being damaged during processing and makes the battery less likely to have corner cracks.

[0144] like Fig.11 As shown, on the first edge 434, the size r2 of the fourth distance is 0.4mm-1.2mm. That is, 0.4mm≤r2≤1.2mm. The size of R2 can be 0.4mm, 0.6mm, 0.8mm or 1.2mm, etc., which is not limited here. The above setting can prevent the second arc segment 432 of the first edge 434 from being damaged during the processing, and at the same time make the battery less likely to crack at the corners. Preferably, 0.6mm≤r2≤1.0mm.

[0145] Schematically, on the first ridge 434, the dimension R1 of the fifth distance is 0.4mm-1.2mm, that is, 0.4mm≤R1≤1.2mm. Along the direction from the second arc segment 432 to the first arc segment 431, R1 gradually increases, the maximum value of R1 is set according to the second distance, and the minimum value of R1 is set according to the third distance. When R1 is less than 0.4mm, an obvious ridge will appear on the bottom wall 410 of the cavity 300 between the transition arc segment 433 and the second arc segment 432, and wrinkles are likely to appear on the membrane shell between the transition arc segment 433 and the second arc segment 432 of the ridge 430. When R1 is greater than 1.2mm, an obvious ridge will appear on the bottom wall 410 of the cavity 300 between the transition arc segment 433 and the first arc segment 431, and wrinkles are likely to appear on the membrane shell between the transition arc segment 433 and the first arc segment 431 of the ridge 430. The above arrangement can avoid obvious edges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432 , and wrinkles are not likely to appear on the membrane shell between the transition arc segment 433 of the edge portion 430 and the first arc segment 431 or the second arc segment 432 .

[0146] Schematically, on the first edge portion 434, the dimension R2 of the sixth distance is 0.4mm-1.2mm, that is, 0.4mm≤R2≤1.2mm. Along the direction from the second arc segment 432 to the first arc segment 431, R2 gradually increases, the maximum value of R2 is set according to the second distance, and the minimum value of R2 is set according to the fourth distance. When R2 is less than 0.4mm, an obvious edge will appear on the side wall 420 of the cavity 300 between the transition arc segment 433 and the second arc segment 432, and wrinkles are likely to appear on the membrane shell between the transition arc segment 433 and the second arc segment 432 of the edge portion 430. When R2 is greater than 1.2mm, an obvious edge will appear on the side wall 420 of the cavity 300 between the transition arc segment 433 and the first arc segment 431, and wrinkles are likely to appear on the membrane shell between the transition arc segment 433 and the first arc segment 431 of the edge portion 430. The above arrangement can avoid obvious edges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432 , and wrinkles are not likely to appear on the membrane shell between the transition arc segment 433 of the edge portion 430 and the first arc segment 431 or the second arc segment 432 .

[0147] In a possible implementation, the battery cell includes a bent section, the bent section of the battery cell is located on two opposite sides of the battery cell in the second direction, and the second edge portion 435 located on either side of the membrane shell in the second direction is arranged opposite to the bent sections on the two opposite sides of the battery cell in the second direction. Specifically, the battery cell is a wound battery cell, which is formed by stacking and winding a positive electrode sheet, a separator, and a negative electrode sheet, and the battery cell includes two bent sections arranged opposite to each other and a straight section located between the two bent sections.

[0148] like Figure 7 , Fig.10 and Fig.12As shown, on the second edge 435, the dimension of the first distance is a2, and a2 satisfies: T / 2+B≤a2≤T, 0.5mm≤B≤2T / 5, and T is the thickness of the battery cell. Since the position of the second edge 435 is opposite to the bending section of the battery cell, the dimension a2 of the first distance on the second edge 435 is set according to the thickness of the battery cell. B is the radius adjustment value, which can be adjusted and designed according to the actual thickness T of the battery cell. When a2<T / 2+B, the gap between the first arc segment 431 of the second edge 435 and the battery cell is large, and the membrane shell may be concave, causing the second edge 435 to tilt and cause the battery to be too thick; when a2>T, the first arc segment 431 of the second edge 435 may interfere with the battery cell, affecting the battery cell's entry into the shell. The above setting makes it difficult for the second edge 435 to tilt and cause the battery to be too thick, and the battery cell can be smoothly inserted into the shell. Preferably, T / 2+B≤a2≤3T / 4. The above arrangement makes it less likely for the second edge portion 435 to warp up and the battery cell can be inserted into the shell more smoothly.

[0149] like Figure 7 , Fig.10 and Fig.12 As shown, on the second edge 435, the size of the second distance is b2, and b2 satisfies: T / 2-A≤b2≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell. When b2<T / 2-A, the gap between the first arc segment 431 of the second edge 435 and the battery cell is large, and the membrane shell may be concave, causing the second edge 435 to tilt and cause the battery to be too thick; when b2>T / 2, the first arc segment 431 of the second edge 435 may interfere with the battery cell, affecting the battery cell's entry into the shell. By setting the size of the second distance on the second edge 435, the second edge 435 is not prone to tilting, causing the battery to be too thick, and the battery cell can be smoothly inserted into the shell. Preferably, T / 2-0.5≤b2≤T / 2, the second edge 435 is less likely to tilt and the battery cell can be more smoothly inserted into the shell.

[0150] When the battery cell is a wound battery cell, on the second edge portion 435 , the dimension of the third distance is r3, and r3 satisfies: T / 2-A≤r3≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell.

[0151] That is to say, the third distance dimension r3 of the second arc segment 432 on the second edge 435 is set according to the thickness of the battery cell. When r3<T / 2-A, the arc radius of the second arc segment 432 of the second edge 435 is small, and the membrane shell is easily damaged at the position of the second arc segment 432 of the second edge 435 during the processing of the cavity 300 by stamping; when r3>T / 2, the gap between the second arc segment 432 of the second edge 435 and the battery cell is small, and the battery may crack at an angle. In other words, through the above setting, the second arc segment 432 of the second edge 435 can be prevented from being damaged during the processing, and the battery is not prone to crack at an angle. Preferably, the arc radius r3 of the second arc segment 432 satisfies: T / 2-0.5≤r3≤T / 2. The above setting can further prevent the second arc segment 432 of the second edge 435 from being damaged during the processing, and the battery is less likely to crack at an angle.

[0152] When the battery cell is a wound battery cell, the size of the fourth distance on the second edge 435 is r4, and r4 satisfies: T / 2-A≤r4≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell. The size r4 of the fourth distance is set according to the thickness T of the battery cell to avoid damage to the second arc segment 432 of the second edge 435 during processing, and at the same time, the battery is not prone to corner cracks. Preferably, T / 2-0.5≤r4≤T / 2.

[0153] When the battery cell is a wound battery cell, the size of the fifth distance on the second edge 435 is R3, and R3 satisfies: T / 2-A≤R3≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell. Among them, R3 gradually increases from the second arc segment 432 to the first arc segment 431. The minimum value of R3 can be set according to r3, and the maximum value of R3 can be set according to b2. T / 2-A≤R3≤T / 2 can avoid the appearance of obvious edges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432, so that the second edge 435 is not prone to wrinkles.

[0154] When the battery cell is a wound battery cell, on the second edge portion 435, the size of the sixth distance is R4, and R4 satisfies: T / 2-A≤R4≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell. Among them, R4 gradually increases from the second arc segment 432 to the first arc segment 431. The minimum value of R4 can be set according to r4, and the maximum value of R4 can be set according to b2. T / 2-A≤R4≤T / 2 can avoid the appearance of obvious edges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432, so that the second edge portion 435 is not prone to wrinkles.

[0155] In another possible implementation, the battery cell is a laminated battery cell, and the second edge portion 435 is arranged opposite to the edge of the battery cell in the second direction. Specifically, the laminated battery cell is formed by staggered stacking of a plurality of positive electrode sheets, a plurality of negative electrode sheets, and a separator.

[0156] When the cavity 300 is used to accommodate a laminated battery cell, the dimension a2 of the first distance on the second edge 435 is 1.2 mm-3 mm, that is, 1.2 mm ≤ a2 ≤ 3 mm. Schematically, when the cavity 300 is used to accommodate a laminated battery cell, the cross-sectional shape and size of the first arc segment 431 of the second edge 435 are respectively the same as the first arc segment 431 of the first edge 434. The dimension a2 of the first distance on the second edge 435 makes it difficult for the second edge 435 to warp up, resulting in an excessively thick battery, and the battery cell can be smoothly inserted into the shell.

[0157] When the cavity 300 is used to accommodate a laminated battery cell, the second distance b2 on the second edge 435 is 0.4 mm to 1.2 mm. The second distance b2 on the second edge 435 makes it difficult for the second edge 435 to warp and cause the battery to be too thick, and the battery cell can be smoothly inserted into the shell.

[0158] When the cavity 300 is used to accommodate a laminated battery cell, the dimension r3 of the third distance on the second edge 435 is 0.4 mm-1.2 mm, that is, 0.4 mm ≤ r3 ≤ 1.2 mm. By setting the dimension r3 of the third distance on the second edge 435, the second arc segment 432 of the first edge 434 can be prevented from being damaged during processing, and the battery is not prone to corner cracking.

[0159] When the cavity 300 is used to accommodate a laminated battery cell, the fourth distance r4 on the second edge 435 is 0.4 mm-1.2 mm, that is, 0.4 mm ≤ r4 ≤ 1.2 mm. By setting the fourth distance r4 on the second edge 435, the second arc segment 432 of the first edge 434 can be prevented from being damaged during processing, and the battery is not prone to corner cracking.

[0160] When the cavity 300 is used to accommodate a laminated battery cell, the dimension R3 of the fifth distance on the second edge portion 435 is 0.4 mm-1.2 mm, that is, 0.4 mm ≤ R3 ≤ 1.2 mm. The above arrangement can avoid the appearance of obvious edges between the transition arc segment 433 on the second edge portion 435 and the first arc segment 431 or the second arc segment 432, resulting in wrinkles on the second edge portion 435.

[0161] When the cavity 300 is used to accommodate a laminated battery cell, the sixth distance R4 on the second edge portion 435 is 0.4 mm-1.2 mm, that is, 0.4 mm ≤ R4 ≤ 1.2 mm. The above arrangement can avoid the appearance of obvious edges between the transition arc segment 433 on the second edge portion 435 and the first arc segment 431 or the second arc segment 432, resulting in wrinkles on the second edge portion 435.

[0162] Indicatively, Figure 7 , Fig. 9 and Fig.11 As shown, the size of the third distance on the same second arc segment 432 is equal to the size of the fourth distance. Exemplarily, the cross section of the second arc segment 432 in its own length direction is an arc, and the arc is tangent to the bottom wall 410 and the side wall 420 of the cavity 300, respectively, and the size of the third distance and the size of the fourth distance are respectively equal to the radius of the arc. Through the above arrangement, it is convenient to set the arc surface of the punch, and then to set the second arc segment 432.

[0163] Indicatively, Figure 7 and Fig.11 As shown, the size of the fifth distance on the same transition arc segment 433 is equal to the size of the sixth distance. Exemplarily, the cross section of the transition arc segment 433 in its own length direction is an arc, and the arc is tangent to the bottom wall 410 and the side wall 420 of the cavity 300, respectively, and the size of the fifth distance and the size of the sixth distance are respectively equal to the radius of the arc. Through the above arrangement, it is convenient to set the arc surface of the punch, and then to facilitate the arrangement of the transition arc segment 433.

[0164] like Fig.12 As shown, the boundary line between the ridge 430 and the bottom wall 410 is a line segment M (composed of line segments M1 to M5), and the boundary line between the ridge 430 and the side wall 420 is a line segment N (composed of line segments N1 to N5). The distances from M1 to M5 to the reference plane (the plane where the opening of the cavity 300 is located) are equal to the depth D of the cavity 300, the distances from N1 and N5 to the reference plane are Dr (the difference between the depth of the cavity 300 and the third distance), the distances from N2 and N4 to the reference plane are DR (the difference between the depth of the cavity 300 and the fifth distance), and the distance from N3 to the reference plane is Da (the difference between the depth of the cavity 300 and the first distance).

[0165] The membrane housing and the battery of the present application are described in detail below through specific embodiments. The specific differences between the following batteries are shown in Table 1 and Table 2.

[0166] Example 1

[0167] 1. Preparation of positive electrode:

[0168] A positive electrode active material slurry is prepared, the positive electrode active material is coated on the surface of the aluminum foil, and the positive electrode sheet is obtained through baking, rolling and slitting.

[0169] The preparation method of the positive electrode active material coating provided in this embodiment is as follows: after the conductive agent and PVDF glue are evenly mixed, lithium cobalt oxide is added and stirred evenly to obtain a positive electrode active material layer slurry.

[0170] The positive electrode active material layer is composed of 97.6 parts by mass of lithium cobalt oxide, 1.05 parts by mass of PVDF, and 1.35 parts by mass of a conductive agent, wherein the conductive agent is composed of conductive carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0171] 2. Preparation of negative electrode sheet:

[0172] A negative electrode slurry is prepared, coated on a carbon-coated copper foil, and then baked, rolled and cut to obtain a negative electrode sheet.

[0173] The preparation method of the negative electrode active material coating is as follows: 0.5% by mass of a conductive agent and 97% by mass of graphite powder are mixed evenly, and then deionized water, 1.3% by mass of carboxymethyl cellulose and 1.2% by mass of styrene-butadiene rubber adhesive are added respectively and stirred evenly to obtain a negative electrode active material layer slurry.

[0174] 3. Cell preparation:

[0175] The positive and negative electrode sheets are prepared and stacked to obtain a battery cell (battery cell thickness T, T=5.0 mm), wherein the battery cell is a stacked battery cell.

[0176] 4. Membrane shell preparation:

[0177] After the aluminum-plastic film is punched, a first shell 100 and a second shell 200 are obtained. The first shell 100 has a cavity 300, and the cavity 300 has four edges 430. Each edge 430 includes a first arc segment 431, two second arc segments 432 and two transition arc segments 433. The first arc segment 431 is located in the middle of the corresponding edge 430, and the two second arc segments 432 are respectively located at both ends of the corresponding edge 430. The transition arc segment 433 is connected between the first arc segment 431 and the second arc segment 432.

[0178] The first arc segment 431 has a first endpoint and a second endpoint on a cross section perpendicular to its own length direction. Along the depth direction of the cavity 300, there is a first distance between the first endpoint and the second endpoint. Along a preset direction, there is a second distance between the first endpoint and the second endpoint, and the preset direction is perpendicular to the depth direction of the cavity 300 and the length direction of the edge 430. The second arc segment 432 has a third endpoint and a fourth endpoint on a cross section perpendicular to its own length direction. Along the depth direction of the cavity 300, there is a third distance between the third endpoint and the fourth endpoint. Along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint. The transition arc segment 433 has a fifth endpoint and a sixth endpoint on a cross section perpendicular to its own length direction. Along the depth direction of the cavity 300, there is a fifth distance between the fifth endpoint and the sixth endpoint. Along the preset direction, there is a sixth distance between the fifth endpoint and the sixth endpoint.

[0179] The first distance dimension of the first arc segment 431 of each edge portion 430 is 1 mm, the second distance dimension is 0.8 mm, and the first arc segment 431 accounts for 35% of the length of the corresponding edge portion 430. The third distance dimension of the second arc segment 432 of each edge portion 430 is 0.4 mm, and the fourth distance dimension is 0.4 mm. The second arc segment 432 accounts for 20% of the length of the corresponding edge portion 430. The fifth distance dimension of the transition arc segment 433 of each edge portion 430 is between the third distance dimension and the second distance dimension, and the sixth distance dimension is between the fourth distance dimension and the second distance dimension. The transition arc segment 433 accounts for 10% of the length of the corresponding edge portion 430.

[0180] It is worth mentioning that the two ends of the edge portion 430 form an angle, so that the sum of the lengths of the first arc segment 431 of the first edge portion 434 , the two transition arc segments 433 and the two second arc segments 432 is less than 100%.

[0181] 5. Assembly:

[0182] The battery cell is placed in the cavity 300 of the first shell 100, the first shell 100 and the second shell 200 are packaged, and the lithium-ion battery is obtained through baking, liquid injection, formation, sorting, secondary sealing, OCV and packaging. Among them, the P-JR GAP is 0.4 and the PA GAP is 1.3.

[0183] Among them, the thickness of the aluminum-plastic film shell is 70-200μm.

[0184] The active material of the positive electrode active material layer includes one or more of lithium cobalt oxide, lithium iron phosphate, nickel cobalt manganese lithium, nickel cobalt aluminum lithium, lithium manganese oxide and lithium-rich manganese-based lithium.

[0185] The negative electrode active material layer includes, but is not limited to, one or more of natural graphite, artificial graphite, mesophase carbon microbeads, lithium titanate, silicon negative electrode, silicon-carbon negative electrode and alloy negative electrode.

[0186] Among them, the positive electrode adhesive is mainly polyvinylidene fluoride (PVDF) adhesive, and the negative electrode adhesive is mainly styrene-butadiene rubber.

[0187] The conductive agent includes at least one of conductive carbon black, Ketjen black, single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0188] Example 2 to Example 31

[0189] The difference from Example 1 lies in that the number of edges 430 of the cavity 300 in the membrane shell (the number of edges 430 in Example 30 is two, the two edges 430 are arranged opposite to each other along the first direction, and the pole ear of the battery cell extends out of the cavity 300 along the first direction; the number of edges 430 in Example 31 is one, and the edge 430 is located on one side of the cavity 300 along the first direction, and the pole ear of the battery cell extends out of the cavity 300 along the first direction), the first distance, the second distance, the length ratio of the first arc segment 431 to the corresponding edge 430 of each edge 430, the third distance, the fourth distance, the length ratio of the second arc segment 432 to the corresponding edge 430 of each edge 430, the fifth distance, the sixth distance of the transition arc segment 433 of each edge 430, and the length ratio of the transition arc segment 433 to the corresponding edge 430 are different. See Table 1 and Table 2 for details. Except for the differences shown in Table 1, the other conditions are the same as those in Example 1.

[0190] Embodiment 32

[0191] The difference from Example 1 is that the battery cell is a wound battery cell, and the thickness T of the battery cell is 5.0 mm.

[0192] The cavity 300 of the first shell 100 has two first edges 434 and two second edges 435. The two first edges 434 are arranged opposite to each other along the first direction, and the two second edges 435 are arranged opposite to each other along the second direction. The tabs of the battery cell extend out of the cavity 300 along the first direction. Each first edge 434 and each second edge 435 includes a first arc segment 431, two second arc segments 432 and two transition arc segments 433.

[0193] The first distance of the first arc segment 431 of each first edge portion 434 is 1.5 mm, the second distance is 1 mm, and the first arc segment 431 accounts for 35% of the length of the corresponding first edge portion 434. The third distance of the second arc segment 432 of each first edge portion 434 is 0.8 mm, and the fourth distance is 0.8 mm. The second arc segment 432 accounts for 20% of the length of the corresponding first edge portion 434. The fifth distance of the transition arc segment 433 of each first edge portion 434 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the fifth distance is 0.8 mm, and the maximum value of the fifth distance is 1 mm. The sixth distance of the transition arc segment 433 of each first edge portion 434 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the sixth distance is 0.8 mm, and the maximum value of the sixth distance is 1 mm. The transition arc segment 433 accounts for 10% of the length of the corresponding first edge portion 434.

[0194] The first distance of the first arc segment 431 of each second edge portion 435 is 3 mm, the second distance is 2.5 mm, and the first arc segment 431 accounts for 35% of the length of the corresponding second edge portion 435. The third distance of the second arc segment 432 of each second edge portion 435 is 2 mm, and the fourth distance is 2 mm. The second arc segment 432 accounts for 20% of the length of the corresponding second edge portion 435. The fifth distance of the transition arc segment 433 of each second edge portion 435 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the fifth distance is 2 mm, and the maximum value of the fifth distance is 2.5 mm. The sixth distance of the transition arc segment 433 of each second edge portion 435 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the sixth distance is 2 mm, and the maximum value of the sixth distance is 2.5 mm. The transition arc segment 433 accounts for 10% of the length of the corresponding second edge portion 435.

[0195] Embodiment 33 to Embodiment 40

[0196] The difference from Example 32 is that the first distance, the second distance of the first arc segment 431 of each second edge 435, the third distance, the fourth distance of the second arc segment 432 of each second edge 435, the fifth distance and the sixth distance of the transition arc segment 433 of each second edge 435 are different, see Table 1 and Table 2 for details. Except for the differences shown in Table 1, the other conditions are the same as those of Example 1.

[0197] Comparative Example 1

[0198] The difference from the first embodiment is that the edge of the cavity 300 is an arc segment with an arc radius of 0.4 mm (arc segments with different arc radii are not provided). The other conditions are the same as the first embodiment.

[0199] Comparative Example 2

[0200] The difference from Example 1 is that the first distance of the first arc segment 431 of each edge portion 430 is 2 mm, and the second distance is 2 mm. The third distance of the second arc segment 432 of each edge portion 430 is 0.4 mm, and the fourth distance is 0.4 mm. The fifth distance of the transition arc segment 433 of each edge portion 430 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the fifth distance is 0.4 mm, and the maximum value of the fifth distance is 2 mm. The sixth distance of the transition arc segment 433 of each edge portion 430 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the sixth distance is 0.4 mm, and the maximum value of the sixth distance is 2 mm. The remaining conditions are the same as those of Example 1.

[0201] Comparative Example 3

[0202] The difference from Example 1 is that the first distance of the first arc segment 431 of each edge portion 430 is 0.8 mm, and the second distance is 2 mm. The third distance of the second arc segment 432 of each edge portion 430 is 0.4 mm, and the fourth distance is 0.4 mm. The fifth distance of the transition arc segment 433 of each edge portion 430 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the fifth distance is 0.4 mm, and the maximum value of the fifth distance is 0.8 mm. The sixth distance of the transition arc segment 433 of each edge portion 430 gradually increases from the second arc segment 432 to the first arc segment 431, the minimum value of the sixth distance is 0.4 mm, and the maximum value of the sixth distance is 0.8 mm. The remaining conditions are the same as those of Example 1.

[0203] Table 1:

[0204]

[0205]

[0206]

[0207] Table 2:

[0208]

[0209]

[0210] The relevant performances of the batteries in the above embodiments and comparative examples were tested, and the test results are recorded in Table 3. The test method is as follows:

[0211] 1. 25℃ cycle test: At 25℃, charge to 4.5V at 1.5C rate, and then discharge to 3.0V at 0.5C rate; perform charge and discharge cycles according to this process to detect the number of cycles when the edge of the lithium-ion battery is warped, or detect whether the edge of the lithium-ion battery is warped after 1200 cycles, and detect whether the battery has corner cracks after 1000 cycles, or detect the number of cycles when corner cracks occur.

[0212] 2. 45℃ cycle test: At 45℃, charge to 4.5V at 1.8C rate, and then discharge to 3.0V at 0.8C rate; perform charge and discharge cycles according to this process to detect the number of cycles when the edge of the lithium-ion battery is warped, or detect whether the edge of the lithium-ion battery is warped after 1200 cycles, and detect whether the battery has corner cracks after 800 cycles, or detect the number of cycles when corner cracks occur.

[0213] The edge warping means that, in the thickness direction of the battery, the warped portion exceeds the outer side surface of the bottom wall 410, resulting in an excessively thick battery.

[0214] 3. After placing the battery cell in the cavity 300 of the membrane shell and manufacturing the battery, observe the appearance of the battery and detect the area where the membrane shell has wrinkles. The wrinkle area should not exceed 2mm. 2 When the battery is inserted into the shell normally, the wrinkle area exceeds 2mm. 2 But not more than 4mm 2 When the wrinkle area exceeds 4mm, it indicates that the battery cell is slightly difficult to insert into the shell; 2 , it indicates that the process of inserting the battery cell into the shell is difficult.

[0215] Table 3:

[0216]

[0217]

[0218] Compared with Comparative Examples 1 to 3, in Examples 1 to 31, the edge 430 of the membrane shell adopts a different arc segment design. The edge 430 includes a first arc segment 431, two second arc segments 432 located at both ends of the edge 430, and a transition arc segment 433 located between the first arc segment 431 and the second arc segment 432, which can effectively solve the warping problem of the battery membrane shell and improve the cycle life of the battery.

[0219] Further, compared with Example 1 and Example 5, Example 2 to Example 4 control the first distance of the first arc segment 431 of each edge portion 430 within the range of 1.2 mm-3 mm, which is beneficial to solve the problem of the battery membrane shell warping while the wrinkle area of ​​the membrane shell is small, which is convenient for the battery cell to enter the shell while ensuring the appearance of the battery. The wrinkle area of ​​the membrane shell is small, which is beneficial to ensure the overall structural strength of the membrane shell.

[0220] Furthermore, compared with Example 6 and Example 10, Examples 7 to 9 control the second distance of the first arc segment 431 of each edge 430 within the range of 0.4 mm-1.2 mm, which is beneficial for solving the problem of battery membrane shell warping while reducing the wrinkle area of ​​the membrane shell, making it easier for the battery cell to enter the shell while ensuring the appearance of the battery.

[0221] Embodiments 11 to 14 show that by controlling the third distance and the fourth distance of the second arc segment 432 of each edge portion 430 to be within the range of 0.4 mm-1.2 mm, it is beneficial to solve the problems of battery membrane shell warping and corner cracking while the wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0222] Furthermore, compared with Example 15 and Example 19, Example 16 to Example 18 control the ratio of the length of the first arc segment 431 to the length of the edge 430 to be 30%-70%, thereby improving the corner cracking and warping problems of the battery membrane shell and increasing the battery cycle life. The wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0223] Furthermore, compared with Example 20 and Example 24, Example 21 to Example 23 control the ratio of the length of the second arc segment 432 to the length of the edge 430 to be 5%-30%, thereby improving the corner cracking and warping problems of the battery membrane shell and increasing the battery cycle life. The wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0224] Furthermore, compared with Example 25 and Example 29, Example 26 to Example 28 control the ratio of the length of the transition arc segment 433 to the length of the edge 430 to be 5%-25%, thereby improving the corner cracking and warping problems of the battery membrane shell and increasing the battery cycle life. The wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0225] Furthermore, by comparing Example 12, Example 30 and Example 31, the greater the number of the edges 430 , the better the improvement effect on the warping problem of the battery membrane shell. When the number of the edges 430 increases, the wrinkle area of ​​the membrane shell can be reduced, which makes it easier to put the battery cell into the shell and ensure the appearance of the battery.

[0226] It can be concluded from Examples 32 to 34 that when the battery cell is a rolled core, by controlling the first distance of the first arc segment 431 of each edge 430 to be within the range of T / 2+B~T (0.5mm≤B≤2T / 5), the corner cracking and warping problems of the battery membrane shell can be improved. The wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0227] It can be concluded from Examples 35 to 37 that when the battery cell is a rolled core, by controlling the second distance of the first arc segment 431 of each edge 430 to be within the range of T / 2-A to T / 2 (0.5mm≤A≤2T / 5), it is possible to improve the corner cracking and warping problems of the battery membrane shell and increase the battery cycle life. The wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0228] It can be concluded from Examples 38 to 40 that when the battery cell is a rolled core, by controlling the third distance dimension and the fourth distance dimension of the first arc segment 431 of each edge 430 to be respectively within the range of T / 2-A to T / 2 (0.5mm≤A≤2T / 5), the corner cracking and warping problems of the battery membrane shell can be improved, and the battery cycle life can be improved. The wrinkle area of ​​the membrane shell is small, which facilitates the insertion of the battery cell into the shell while ensuring the appearance of the battery.

[0229] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A membrane shell, characterized in that: The membrane shell is provided with a cavity (300), and the cavity (300) includes a bottom wall (410), a side wall (420) arranged around the bottom wall (410), and an edge portion (430) connected between the bottom wall (410) and the side wall (420); Along the length direction of the edge portion (430), the edge portion (430) includes a first arc segment (431), second arc segments (432) located at two opposite ends of the first arc segment (431), and a transition arc segment (433) connected between the first arc segment (431) and the second arc segment (432); The first arc segment (431) has a first end point and a second end point in a cross section perpendicular to its length direction, the first end point is connected to the bottom wall (410), and the second end point is connected to the side wall (420); Along the depth direction of the cavity (300), there is a first distance between the first endpoint and the second endpoint; along a preset direction, there is a second distance between the first endpoint and the second endpoint, and the preset direction is perpendicular to the depth direction of the cavity (300) and the length direction of the edge (430) respectively; The first distance is larger than the second distance.

2. The membrane housing according to claim 1, characterized in that The second arc segment (432) has a third endpoint and a fourth endpoint in a cross section perpendicular to its length direction, the third endpoint is connected to the bottom wall (410), and the fourth endpoint is connected to the side wall (420); Along the depth direction of the cavity (300), there is a third distance between the third endpoint and the fourth endpoint; along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint; The size of the third distance and the size of the fourth distance are both smaller than or equal to the size of the second distance.

3. The membrane housing according to claim 2, characterized in that The transition arc segment (433) has a fifth end point and a sixth end point on a cross section perpendicular to its length direction, the fifth end point is connected to the bottom wall (410), and the sixth end point is connected to the side wall (420); Along the depth direction of the cavity (300), there is a fifth distance between the fifth endpoint and the sixth endpoint; along the preset direction, there is a sixth distance between the fifth endpoint and the sixth endpoint; The size of the fifth distance is between the size of the third distance and the size of the second distance, and the size of the sixth distance is between the size of the fourth distance and the size of the second distance.

4. The membrane housing according to claim 2, characterized in that The first arc segment (431) is tangent to the bottom wall (410) and the side wall (420) respectively; and / or, The transition arc segment (433) is tangent to the bottom wall (410) and the side wall (420) respectively; and / or, The second arc segment (432) is tangent to the bottom wall (410) and the side wall (420) respectively.

5. The membrane housing according to claim 2, characterized in that Along the length direction of the edge portion (430), the ratio of the length of the first arc segment (431) to the length of the edge portion (430) is 30%-70%; and / or, Along the length direction of the edge portion (430), the ratio of the length of the second arc segment (432) to the length of the edge portion (430) is 5%-30%; and / or, Along the length direction of the edge portion (430), the ratio of the length of the transition arc segment (433) to the length of the edge portion (430) is 5%-25%.

6. The membrane housing according to any one of claims 1 to 5, characterized in that: The membrane shell comprises a first shell (100) and a second shell (200), wherein the first shell (100) is covered on the second shell (200); At least one of the first shell (100) and the second shell (200) is provided with the cavity (300), and has the bottom wall (410), the side wall (420) and the edge portion (430) connected between the bottom wall (410) and the side wall (420).

7. The membrane housing according to any one of claims 1 to 5, characterized in that: Along the length direction of the edge portion (430), the second arc segments (432) at two opposite ends of the first arc segment (431) have the same length; And / or, along the length direction of the edge portion (430), the transition arc segments (433) at two opposite ends of the first arc segment (431) have the same length.

8. The membrane housing according to any one of claims 1 to 5, characterized in that: The membrane shell comprises an aluminum layer; the thickness of the aluminum layer of the membrane shell at the first arc segment (431) is greater than the thickness of the aluminum layer of the membrane shell at the transition arc segment (433); And / or, the membrane shell includes an aluminum layer; the thickness of the aluminum layer of the membrane shell at the transition arc segment (433) is greater than the thickness of the aluminum layer of the membrane shell at the second arc segment (432).

9. A battery, characterized in that: It comprises a battery cell and a membrane shell according to any one of claims 1 to 8, wherein the battery cell is arranged in a cavity (300) of the membrane shell.

10. The battery according to claim 9, characterized in that The edge portion comprises a first edge portion (434) and a second edge portion (435), the first edge portion (434) being located at an end of the cavity along a first direction, and the first edge portion (434) being arranged opposite to an edge of the battery cell in the first direction; The first edge portion (434) and the second edge portion (435) both include a first arc segment (431), a second arc segment (432) and a transition arc segment (433); the second arc segment (432) has a third endpoint and a fourth endpoint in a cross section perpendicular to its own length direction; along the depth direction of the cavity (300), there is a third distance between the third endpoint and the fourth endpoint; along the preset direction, there is a fourth distance between the third endpoint and the fourth endpoint; the transition arc segment (433) has a fifth endpoint and a sixth endpoint in a cross section perpendicular to its own length direction; along the depth direction of the cavity (300), there is a fifth distance between the fifth endpoint and the sixth endpoint; along the preset direction, there is a sixth distance between the fifth endpoint and the sixth endpoint; On the first edge portion (434), the first distance is 1.2 mm to 3 mm; and / or, On the first edge portion (434), the second distance is 0.4 mm to 1.2 mm; and / or, On the first edge portion (434), the third distance is 0.4 mm to 1.2 mm; and / or, On the first edge portion (434), the fourth distance is 0.4 mm to 1.2 mm; and / or, On the first edge portion (434), the size of the fifth distance is 0.4 mm-1.2 mm; and / or, On the first edge portion (434), the size of the sixth distance is 0.4 mm-1.2 mm.

11. The battery according to claim 10, characterized in that The battery cell comprises a bending section, the bending section of the battery cell is located on two opposite sides of the battery cell in the second direction, and the second edge portion (435) located on either side of the membrane shell in the second direction is arranged opposite to the bending section on two opposite sides of the battery cell in the second direction; On the second edge portion (435), the dimension of the first distance is a2, and a2 satisfies: T / 2+B≤a2≤T, 0.5mm≤B≤2T / 5, T is the thickness of the battery core; and / or, On the second edge portion (435), the size of the second distance is b2, and b2 satisfies: T / 2-A≤b2≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery core; and / or, On the second edge portion (435), the dimension of the third distance is r3, and r3 satisfies: T / 2-A≤r3≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery core; and / or, On the second edge portion (435), the size of the fourth distance is r4, and r4 satisfies: T / 2-A≤r4≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery core; and / or, On the second edge portion (435), the size of the fifth distance is R3, and R3 satisfies: T / 2-A≤R3≤T / 2, 0.5mm≤A≤2T / 5, T is the thickness of the battery core; and / or, On the second edge portion (435), the dimension of the sixth distance is R4, and R4 satisfies: T / 2-A≤R4≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell.

12. The battery according to claim 10, characterized in that The battery core is a laminated battery core, and the second edge portion (435) is arranged opposite to the edge of the battery core in the second direction; On the second edge portion (435), the first distance is 1.2 mm to 3 mm; and / or, On the second edge portion (435), the second distance is 0.4 mm to 1.2 mm; and / or, On the second edge portion (435), the third distance is 0.4 mm to 1.2 mm; and / or, On the second edge portion (435), the fourth distance is 0.4 mm to 1.2 mm; and / or, On the second edge portion (435), the size of the fifth distance is 0.4 mm-1.2 mm; and / or, On the second edge portion (435), the size of the sixth distance is 0.4 mm-1.2 mm.

13. The battery according to any one of claims 10 to 12, characterized in that: The size of the third distance on the same second arc segment is equal to the size of the fourth distance; and / or, The size of the fifth distance on the same transition arc segment (433) is equal to the size of the sixth distance.

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