Membrane shell and battery

Abstract

The application relates to the technical field of batteries, in particular to a film shell and a battery. The film shell is provided with a cavity, 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; along the length direction of the ridge part, the ridge part comprises a first arc segment, a second arc segment and a transition arc segment; the first arc segment has a first end point and a second end point on a section perpendicular to the length direction of the first arc segment, the first end point is connected with the bottom wall, and the second end point is connected with the side wall; along the cavity depth direction, the first end point and the second end point have a first distance; along a preset direction, the first end point and the second end point have a second distance, the preset direction is perpendicular to the cavity depth direction and the length direction of the ridge part; the size of the first distance is greater than the size of the second distance. In the cycle process of the battery, the battery film shell is not prone to depression, and the ridge part near the depression part is not prone to over-thickness caused by buckling.

Description

TECHNICAL FIELD

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

[0002] Soft package 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 living quality, people not only pursue high energy density (ED) and long cycle life, but also pay attention to the safety of lithium ion batteries.

[0003] At present, the soft package lithium ion battery includes a film shell and a battery cell. The film shell forms a cavity, and the battery cell is installed inside the cavity. When designing the film shell, a certain space is usually reserved in the length, width and thickness directions of the cavity of the film shell and the battery cell.

[0004] However, when the reserved space is too large, the area between the battery cell and the film shell that is not in contact becomes larger. During the cycle process of the battery, the side wall of the cavity is easily depressed under the action of atmospheric pressure, and the side wall of the cavity near the edge of the cavity is easily warped in the opposite direction, resulting in over-thickness failure. SUMMARY

[0005] Therefore, the present application provides a film shell and a battery to solve the problem that the side wall of the cavity of the film shell is easily depressed under the action of atmospheric pressure during the cycle process of the battery, and the side wall of the cavity near the edge of the cavity is easily warped in the opposite direction, resulting in over-thickness failure.

[0006] In one aspect, the present application provides a film shell, which is provided with a cavity. The cavity includes a bottom wall, a side wall arranged around the bottom wall, and a corner portion connected between the bottom wall and the side wall.

[0007] The corner portion includes a first arc segment, second arc segments respectively located at opposite ends of the first arc segment, and a transition arc segment connected between the first arc segment and the second arc segments along the length direction of the corner portion.

[0008] The first arc segment has a first end point and a second end point in 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] The first distance between the first end point and the second end point is greater than the second distance between the first end point and the second end point along the preset direction.

[0010] The size of the first distance is greater than the size of the second distance.

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

[0012] The third distance is between the third end point and the fourth end point along the depth direction of the cavity; and the fourth distance is between the third end point and the fourth end point along the preset direction.

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

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

[0015] The fifth distance is between the fifth end point and the sixth end point along the depth direction of the cavity; and the sixth distance is between the fifth end point and the sixth end point along the preset direction.

[0016] The fifth distance is between the third distance and the second distance, and the sixth distance is between the fourth distance and 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 segment is tangent to the bottom wall and the side wall 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 ridge, the length of the first arc segment accounts for 30%-70% of the length of the ridge; and / or,

[0023] Along the length direction of the ridge, the length of the second arc segment accounts for 5%-30% of the length of the ridge.

[0024] And / or,

[0025] Along the length direction of the ridge, the length of the transition arc segment accounts for 5%-25% of the length of the ridge.

[0026] In a possible implementation, the membrane shell includes a first shell and a second shell, and the first shell 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 a ridge connected between the bottom wall and the side wall.

[0028] In a possible implementation, along the length direction of the ridge, the lengths of the second arc segments at the two ends of the first arc segment are the same.

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

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

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

[0032] In a possible implementation, the edge comprises a first edge and a second edge, the first edge is located at the end of the cavity in the first direction, and the first edge is arranged opposite to the edge of the battery cell in the first direction.

[0033] The first edge and the second edge each comprise a first arc segment, a second arc segment and a transition arc segment, the second arc segment has a third end point and a fourth end point in the cross section perpendicular to the length direction of the second arc segment, and the third end point and the fourth end point have a third distance in the depth direction of the cavity; the third end point and the fourth end point have a fourth distance in the preset direction; the transition arc segment has a fifth end point and a sixth end point in the cross section perpendicular to the length direction of the transition arc segment, and the fifth end point and the sixth end point have a fifth distance in the depth direction of the cavity; the fifth end point and the sixth end point have a sixth distance in the preset direction.

[0034] The size of the first distance on the first edge is 1.2mm-3mm; and / or,

[0035] The size of the second distance on the first edge is 0.4mm-1.2mm; and / or,

[0036] The size of the third distance on the first edge is 0.4mm-1.2mm; and / or,

[0037] The size of the fourth distance on the first edge is 0.4mm-1.2mm; and / or,

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

[0039] The size of the sixth distance on the first edge is 0.4mm-1.2mm.

[0040] In a possible implementation, the battery cell comprises a bending segment, the bending segment of the battery cell is located on the opposite sides of the battery cell in the second direction, and the second edge located on either side of the film shell in the second direction is arranged opposite to the bending segment on the opposite sides of the battery cell in the second direction.

[0041] The first distance on the second edge portion has a size a2, and a2 satisfies T / 2+B≤a2≤T, 0.5mm≤B≤2T / 5, and T is the thickness of the battery cell; and / or,

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

[0043] The third distance on the second edge portion has a size r3, and r3 satisfies T / 2-A≤r3≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell; and / or,

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

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

[0046] The sixth distance on the second edge portion has a size R4, and R4 satisfies T / 2-A≤R4≤T / 2, 0.5mm≤A≤2T / 5, and 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] The first distance on the second edge portion has a size of 1.2mm-3mm; and / or,

[0049] The second distance on the second edge portion has a size of 0.4mm-1.2mm; and / or,

[0050] The third distance on the second edge portion has a size of 0.4mm-1.2mm; and / or,

[0051] The fourth distance on the second edge portion has a size of 0.4mm-1.2mm; and / or,

[0052] The fifth distance on the second edge portion has a size of 0.4mm-1.2mm; and / or,

[0053] The sixth distance on the second edge portion has a size of 0.4mm-1.2mm.

[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 film shell and the battery provided by the application are provided with a cavity, and the battery cell can be accommodated through the cavity. The cavity includes a bottom wall, a side wall arranged around the bottom wall, and a ridge 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 through the ridge. Along the length direction of the ridge, the ridge includes a first arc segment, a second arc segment respectively located at the opposite ends of the first arc segment, and a transition arc segment connected between the first arc segment and the second arc segment. The first distance between two end points on the cross section of the first arc segment in the cavity depth direction, the second distance between the two end points on the cross section of the first arc segment in the preset direction, and the preset direction is perpendicular to the cavity depth direction and the length direction of the ridge. 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 the end of the cavity side wall facing the battery cell than the arc segment with the first distance equal to the second distance, and the first arc segment can better fit the battery cell. During the battery cycle process, the risk of over-thickness failure caused by the depression of the battery film shell and the buckling of the ridge near the depression part is not easy to occur, so that the battery is not easy to appear over-thickness. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0058] Figure 1 The structure schematic diagram of the film shell in the related art;

[0059] Figure 2 The structure schematic diagram of the film shell before packaging provided by the embodiment of the present application Figure 1 ;

[0060] Figure 3 The structure schematic diagram of the film shell before packaging provided by the embodiment of the present application Figure 2 ;

[0061] Figure 4 The structure schematic diagram of the film shell before packaging provided by the embodiment of the present application Figure 3 ;

[0062] Figure 4 The structure schematic diagram of the film shell before packaging provided by the embodiment of the present application Figure 6 ;

[0063] Figure 1 The structure schematic diagram of the film shell provided by the embodiment of the present application Figure 7 ;

[0064] Figure 8 A schematic view of the membrane shell provided by the embodiment of the present application at a position of one of the edges;

[0065] Figure 9 A schematic view of the membrane shell provided by the embodiment of the present application at a position of the first arc segment;

[0066] Figure 10 A schematic view of the membrane shell provided by the embodiment of the present application at a position of the second arc segment;

[0067] Figure 2 A schematic view of the structure of the membrane shell provided by the embodiment of the present application Figure 11 ;

[0068] Figure 12 A schematic view of the membrane shell provided by the embodiment of the present application at a position of another edge;

[0069] Figure 13 A schematic view of the membrane shell provided by the embodiment of the present application at a position of the edge;

[0070] Figure 1 A schematic view of the structure of the convex mold provided by the embodiment of the present application

[0071] Explanation of reference signs:

[0072] 100 - first shell;

[0073] 200 - second shell;

[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 - convex mold; 510 - bottom surface; 520 - edge surface; 530 - arc surface; 531 - first arc surface; 532 - second arc surface; 533 - transition arc surface. DETAILED DESCRIPTION

[0077] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be combined with the accompanying drawings for the preferred embodiments of the present application to make the technical solutions in the embodiments of the present application more clearly described in more details. In the drawings, the same or similar notations represent the same or similar components or components with the same or similar functions throughout. The described embodiments are part of the embodiments of the present application, not all the embodiments. The embodiments described below by referring to the drawings are exemplary, and are intended to explain the present application, and cannot be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work under the premise of the present application, all belong to the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0078] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or indirect connection through an intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0079] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship 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 device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

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

[0081] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or display including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or displays.

[0082] In the prior art, for example, Figures 2 to 8As shown, the soft package lithium ion battery includes a film shell made of aluminum plastic film and an electric core. The film shell forms a cavity, and the electric core is installed inside the cavity. The cavity is generally formed by punch stamping, and the bottom wall and the side wall of the cavity are connected by a single radius arc-shaped edge 401. Generally, when designing the film shell, a certain space is reserved in the length, width and thickness directions of the cavity of the film shell and the electric core. However, when the reserved space is too large, the area between the electric core and the film shell that is not in contact becomes larger, and during the battery cycle process, the side wall of the cavity is easily depressed under the action of atmospheric pressure, and the side wall of the cavity near the edge of the cavity is easily raised in the opposite direction, causing over-thickness failure.

[0083] Although shaping the side edge of the battery film shell with a clamp or the like can improve the protrusion of the edge of the battery film shell, the improvement effect on the battery expansion is limited, and the pole piece of the electric core inside the cavity is easily damaged, the film shell is damaged, and the appearance of the battery is poor. In addition, after a period of shaping, the edges are easily rebounded and protruded again, causing cycle thickness expansion failure.

[0084] At present, the side edge (bending section) of the winding type battery is actually an arc surface (not a perfect circle) close to a perfect circle, so the transition surface designed with a circular arc surface cannot perfectly fit the electric core. In order to reduce the risk of angle cracking of the battery during long cycle, generally, when designing the film shell, a certain space is reserved in the length, width and thickness directions of the film shell and the battery. When the reserved space is too large, the reserved space between the end of the electric core towards 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, and the side wall of the cavity will be depressed towards the electric core under the action of atmospheric pressure, and the edge of the film shell near the depressed part will be raised in the opposite direction, causing over-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 of the middle part of the edge can better fit the electric core in the cavity. In this way, the middle part of the edge can better fit the electric core, and the battery is not easy to cause the depression of the battery film shell and the over-thickness failure caused by the edge near the depressed part during the cycle process, so that the battery is not easy to cause over-thickness.

[0086] Therefore, the inventors design a film shell and a battery. The bottom wall of the cavity of the film shell is connected with the side wall through a ridge. The middle part of the ridge is provided with a first arc segment, and the two ends of the ridge are provided with a second arc segment. The first arc segment and the second arc segment are connected through a transition arc segment. In the depth direction of the cavity, the first arc segment has a first distance between two end points in the cross section perpendicular to the length direction of the first arc segment. In the direction perpendicular to the depth direction of the cavity and the length direction of the ridge, the first arc segment has a second distance between two end points in the cross section perpendicular to the length direction of the first arc segment. The size of the first distance is greater than the size of the second distance. The first arc segment in the middle part of the ridge is more suitable for the battery cell in the cavity, and the risk of over-thickness failure caused by the depression of the battery film shell and the warping of the ridge near the depression part during the cycle of the battery is reduced.

[0087] The technical solutions of the film shell and the battery provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0088] Referring to Figure 7 The film shell provided by the embodiments of the present application is provided with a cavity 300. The cavity 300 of the film shell can be used to accommodate a battery cell. The material of the film shell can be an aluminum plastic film. A punch can be used to stamp the aluminum plastic film to form the cavity 300 on the film shell.

[0089] The cavity 300 includes a bottom wall 410, a side wall 420 surrounding the bottom wall 410, and a ridge 430 connected between the bottom wall 410 and the side wall 420. For example, the cavity 300 includes a bottom wall 410 and four side walls 420 surrounding the bottom wall 410. After the film shell is formed with the cavity 300, the film shell also has an opening communicating with the cavity 300, and the bottom wall 410 of the cavity 300 is located away from the opening. The ridge 430 of the film shell forms a ridge edge on the side of the cavity 300 away from the opening.

[0090] In one possible implementation, each side wall 420 is connected with the bottom wall 410 through the ridge 430, that is, the number of ridges 430 can be the same as the number of side walls 420. In another possible implementation, part of the side walls 420 are connected with the bottom wall 410 through the ridge 430, that is, the number of ridges 430 can be less than the number of side walls 420. For example, when the cavity 300 has four side walls 420, the number of ridges 430 can be one, two or three, etc.

[0091] 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 transition arc segments 433 connected between the first arc segment 431 and the second arc segments 432 along the length direction of the ridge 430. 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. For example, the cross sections of the second arc segments 432 and the transition arc segments 433 can be circular arcs respectively, the curvatures of the cross sections of the second arc segments 432 are consistent, and the curvatures of the cross sections of the transition arc segments 433 are consistent. 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 corner of the diaphragm case.

[0092] The first arc segment 431 has a first end point and a second end point in the cross section perpendicular to the length direction of the first arc segment 431, the first end point is connected with the bottom wall 410, and the second end point is connected with the side wall 420. It can be understood that the first end point is the connection point between the first arc segment 431 and the bottom wall 410, and the second end point is the connection point between the first arc segment 431 and the side wall 420. For example, the diaphragm case can be cut to obtain the cross section of the first arc segment 431, and the positions and distances of the first end point and the second end point in the cross section can be obtained by a profile measuring instrument. Of course, in another mode, the profile curves of different arc segments on the diaphragm case can be scanned by a laser sensor on the profile measuring instrument to obtain the positions and distances of the two end points of different arc segments.

[0093] The first distance between the first end point and the second end point along the depth direction of the cavity 300, and the second distance between the first end point and the second end point along the preset direction, the preset direction is perpendicular to the depth direction of the cavity 300 and the length direction of the ridge 430 respectively. Figure 7 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 4 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 5 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 4 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 5 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 4 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 5 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 4 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 5 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5. Figure 8 The depth direction of the cavity 300 is the direction indicated by the Q-axis in FIG. 4, and the preset direction is the direction indicated by the P-axis in FIG. 4. The preset direction can be set according to the length direction of the ridge 430 to be cut, for example, for the longer ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the Y-axis in FIG. 4 and FIG. 5, and for the shorter ridge 430 in FIG. 4 and FIG. 5, the preset direction is the direction indicated by the X-axis in FIG. 4 and FIG. 5.

[0094] The dimension of the first distance is greater than the dimension of the second distance. For example, a profile measuring instrument can be used to obtain the dimensions of the first distance and 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 can be placed on the profile measuring platform of the profile measuring instrument; the laser sensor of the profile measuring instrument scans the membrane shell to obtain the profile diagram and dimension data of the membrane shell, and then obtains the dimensions of the first distance and the second distance.

[0095] like Figure 13 As shown, the cross-section of the first arc segment 431 is consistent at all points along its length.

[0096] In one possible implementation, the first arc segment 431 has an elliptical arc in its cross-section perpendicular to the length direction of the edge 430. 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 a predetermined direction. In another possible implementation, the first arc segment 431 has a circular arc in its cross-section perpendicular to the length direction of the edge 430. The distance between the center of this circular arc and the side wall 420 is greater than the distance between the center of this circular arc and the bottom wall 410.

[0097] Those skilled in the art will understand that a membrane shell can be formed by stamping the membrane shell material with a punch. For example... Figures 2-9 As shown, the punch 500 includes a bottom surface 510, a side surface 520, and an arc surface 530 connecting the bottom surface 510 and the side surface 520. The structure of the first ridge 434 matches the arc surface 530, that is, the arc surface 530 includes a first arc surface 531, second arc surfaces 532 located at opposite ends of the first arc surface 531, and a transition arc surface 533 connecting the first arc surface 531 and the second arc surface 532. The first arc surface 531 forms a first arc segment 431, the second arc surface 532 forms a second arc segment 432, and the transition arc surface 533 forms a transition arc segment 433. Along the stamping direction of the punch 500, the first arc surface 531 has two endpoints in its cross-section perpendicular to its own length direction, one endpoint connecting to the bottom surface 510 and the other endpoint connecting to the side surface 520. Along the stamping direction of the punch 500, there is a first gap between the two endpoints; along a predefined direction, there is a second gap between the two endpoints, the predefined direction being perpendicular to both the stamping direction of the punch 500 and the extension direction of the arc surface 530. The first gap is greater than the second gap.

[0098] The film shell provided by the embodiment is connected between the bottom wall 410 and the side wall 420 of the cavity 300 through the 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 respectively, and a transition arc segment 433 connected between the first arc segment 431 and the second arc segment 432. The 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, the second distance between the two end points on the cross section of the first arc segment 431 in the preset direction, and the preset direction is perpendicular to the depth direction of the cavity 300 and the length direction of the edge 430 respectively. The size of the first distance is greater than the size of the second distance. The first arc segment 431 arranged in this way is closer to the end of the side wall 420 of the cavity 300 facing the battery cell than the arc segment with the first distance equal to the second distance, and the first arc segment 431 can better fit the battery cell. During the battery cycle process, the risk of over-thickness failure caused by the depression of the battery film shell and the warping of the edge 430 near the depression part is not easy to occur, so that the battery is not easy to appear over-thickness.

[0099] In one embodiment, as shown in Figure 8 The second arc segment 432 has a third end point and a fourth end point on the cross section perpendicular to the length direction of the second arc segment 432, the third end point is connected with the bottom wall 410, and the fourth end point is connected with the side wall 420. It can be understood that the third end point is the connection point between the second arc segment 432 and the bottom wall 410, and the fourth end point is the connection point between the second arc segment 432 and the side wall 420. For example, the film shell can be cut to obtain the cross section of the second arc segment 432, and the positions of the third end point and the fourth end point in the cross section can be obtained by a profile measuring instrument.

[0100] Along the depth direction of the cavity 300, the third distance between the third end point and the fourth end point. Along the preset direction, the fourth distance between the third end point and the fourth end point. 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 size relationship between the size of the third distance and the size of the fourth distance is not limited in this embodiment, and those skilled in the art can set it according to the needs. As shown in Figures 2-7 The cross section of the second arc segment 432 is consistent along the length direction of the second arc segment 432.

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

[0102] When the battery cell is placed in the cavity 300 of the film shell, due to the size of the first distance being greater than the size of the second distance, and the size of the third distance and the size of the fourth distance being 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. Those skilled in the art can understand that the end of the rib 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 rib edge with a single radius. If a small reserved space is provided between the cavity 300 of the film shell and the battery cell, the battery cell will swell during long cycle, repeatedly pressing and stretching the aluminum plastic film, which can easily cause angular cracking at the angular position of the cavity 300. The film shell provided in the embodiment can reduce the redundancy of the aluminum plastic film at each transition surface by using arc segments with different radii in combination. The battery is not easy to cause over-thickness due to the warping of the rib portion 430 of the film shell, and the second arc segment 432 can provide a larger space between the angular position of the cavity 300 and the battery cell. The film shell is not easy to crack during the long cycle of the battery, and the number of cycles of the battery is increased.

[0104] In a specific embodiment, as shown in Figures 2-5 The fifth end point is the connection point between the cross section of the transition arc segment 433 perpendicular to the length direction thereof and the bottom wall 410, and the sixth end point is the connection point between the cross section of the transition arc segment 433 perpendicular to the length direction thereof and the side wall 420. For example, the transition arc segment 433 of the film shell can be cut to obtain the cross section of the transition arc segment 433, and the positions of the fifth end point and the sixth end point in the cross section can be obtained by a profile measuring instrument.

[0105] The fifth distance between the fifth end point and the sixth end point in the depth direction of the cavity 300. The sixth distance between the fifth end point and the sixth end point in 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 dimensions of the third and fourth distances are smaller than the dimension of the second distance, the dimensions of the fifth and sixth distances both tend to increase in the direction from the second arc segment 432 to the first arc segment 431. The dimensions of the fifth and sixth distances can be obtained using a profilometer. At the end of the transition arc segment 433 facing 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 the end of the transition arc segment 433 facing the second arc segment 432, the fifth and sixth distances can each be equal to the second distance.

[0108] With the above configuration, the edge 430 gradually transitions between the first arc segment 431 and the second arc segment 432, and the membrane shell is less likely to wrinkle at the edge 430 position, which helps to ensure the overall structural strength of the membrane shell.

[0109] like Figure 7 As shown, the membrane shell includes a first shell 100 and a second shell 200, with the first shell 100 covering the second shell 200. The first shell 100 and the second shell 200 can each be sheet-like structures. After the first shell 100 is placed on the second shell 200, it can be fixed by adhesive bonding or heat sealing. In one possible implementation, the first shell 100 and the second shell 200 can be interconnected; for example, the middle portion of the aluminum-plastic film can be bent, with the portions of the aluminum-plastic film on either side of the bent area defining the first shell 100 and the second shell 200, respectively. In another possible implementation, the first shell 100 and the second shell 200 can also be separate structures, meaning the first shell 100 is not connected to the second shell 200 before being placed on top of it.

[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 a rib 430 connected between the bottom wall 410 and the side wall 420. Specifically, the first shell 100 can be stamped to form the cavity 300, the second shell 200 can be stamped to form the cavity 300, or the first shell 100 and the second shell 200 can be respectively stamped to form the cavity 300 on the first shell 100 and the second shell 200. When the first shell 100 and the second shell 200 are respectively provided with the cavity 300, the cavity 300 on the first shell 100 is opposite to the cavity 300 on the second shell 200 after the first shell 100 is covered on the second shell 200. That is, the film shell can be a single-pit film shell or a double-pit film shell. When the first shell 100 is provided with the cavity 300, the cavity 300 has at least one rib 430 described above; when the second shell 200 is provided with the cavity 300, the cavity 300 has at least one rib 430 described above. That is, the bottom wall 410 and the side wall 420 of the cavity 300 are transitioned through the rib 430, and the rib 430 includes a first arc segment 431, a transition arc segment 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 film shell is relatively diverse, and can be specifically arranged according to the to-be-contained battery cell. The battery is not prone to have a depression in the battery film shell and an over-thickness caused by the rib 430 near the depression part during the cycle process.

[0112] In a specific embodiment, as shown in Figure 8 and Figure 8 , the first arc segment 431 is tangent to the bottom wall 410 and the side wall 420, respectively. As shown in Figure 7 , the cross section of the first arc segment 431 is an elliptical arc, L1 and L2 are two tangent lines 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 with point P. The major axis of the elliptical arc is a, the minor axis of the elliptical arc is b, the two foci F1 and F2 of the elliptical arc are located on the straight line where the major axis a is located, the focal distance of the two foci is 2c, and a 2 =b 2 +c 2 . The size of the first distance is equal to the length of the minor axis of the elliptical arc, and the size of the second distance is equal to the length of the major axis of the elliptical arc.

[0113] As shown in Figure 7As shown, the transition arc segment 433 is tangent to the bottom wall 410 and the side wall 420, respectively. For example, the cross-section of the transition arc segment 433 is a circular arc, and the dimensions of the fifth distance and the sixth distance are both equal to the radius of the aforementioned circular arc.

[0114] like Figure 9 and Figure 9 As shown, the second arc segment 432 is tangent to both the bottom wall 410 and the side wall 420. For example, the cross-section of the second arc segment 432 is a circular arc, and the dimensions of the third and fourth distances are both equal to the radius of the aforementioned circular arc. Figure 7 As shown, L3 and L4 are two tangents to the circular arc 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 perpendicular line T3 corresponding to L3 and the perpendicular line T4 corresponding to L4 are relative to point O.

[0115] With the above configuration, the arc segment of the ridge 430 is tangent to the bottom wall 410 and the side wall 420, respectively, so that there are no obvious ridges between the arc segment of the ridge 430 and the bottom wall 410 and the side wall 420. This ensures the appearance of the battery and makes it less likely for the membrane to wrinkle at the ridge 430 position.

[0116] In a specific embodiment, such as Figure 11 and Figure 7 As shown, along the length direction of the edge 430, the ratio of the length (H1 or W1) of the first arc segment 431 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 a range of 30%, 40%, 50%, 60%, 70%, or any two of these, and is not limited to a single value here.

[0117] When the ratio of the length of the first arc segment 431 to the length of the edge 430 is less than 30%, it indicates that the length of the portion with a small gap between the middle of the edge 430 and the cell is small. This has a limited effect on improving the membrane shell depression and the resulting warping of the edge 430, and may lead to membrane shell depression and excessive thickness due to warping of the edge 430 near the depression. When the ratio of the length of the first arc segment 431 to the length of the edge 430 is greater than 70%, the lengths of the transition arc segment 433 and the second arc segment 432 are small, which may cause corner cracks and membrane shell wrinkles during long-cycle operation. In other words, by controlling the ratio between the length of the first arc segment 431 and the length of the edge 430, it is possible to prevent membrane shell depression, prevent excessive battery thickness, and prevent corner cracks or wrinkles in the membrane shell. Preferably, the length of the first arc segment 431 accounts for 30%-60% of the length of the edge 430. The above design makes the edges less prone to dents, the corners of the battery less prone to cracking, and the membrane casing less prone to wrinkles.

[0118] As shown in Figure 11 and Figure 7 shown, along the length direction of the edge portion 430, the length (H1, H5, W1 or W5) of the second arc segment 432 accounts for 5%-30% of the length of the edge portion 430. For example, the length of the second arc segment 432 can account for 5%, 10%, 15%, 20%, 25%, 30% or a range formed by any two of the above percentages of the length of the edge portion 430, without being limited to the above percentages.

[0119] When the length of the second arc segment 432 accounts for less than 5% of the length of the edge portion 430, it means that the length of the space between the end of the edge portion 430 and the battery cell is small, and the battery may have a corner crack during long cycle; when the length of the second arc segment 432 accounts for more than 30% of the length of the edge portion 430, it means that the lengths of the transition arc segment 433 and the first arc segment 431 are small, and the improvement effect of the membrane shell depression and the depression caused by the edge portion 430 is small. That is to say, by setting the ratio of the length of the second arc segment 432 to the length of the edge portion 430, the battery is less likely to have a corner crack during long cycle, and the battery is less likely to have an over-thickness. Preferably, the length of the second arc segment 432 accounts for 10%-25% of the length of the edge portion 430, and the battery is less likely to have a corner crack during long cycle, and the membrane shell is less likely to have a depression that causes the battery to have an over-thickness.

[0120] As shown in Figure 11 and Figure 10 shown, along the length direction of the edge portion 430, the length (H2, H4, W2 or W4) of the transition arc segment 433 accounts for 5%-25% of the length of the edge portion 430. For example, the length of the transition arc segment 433 can account for 5%, 10%, 15%, 20%, 25% or a range formed by any two of the above percentages of the length of the edge portion 430, without being limited to the above percentages.

[0121] When the length of the transition arc segment 433 accounts for less than 5% of the length of the edge portion 430, 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 have a wrinkle; when the length of the transition arc segment 433 accounts for more than 25% of the length of the edge portion 430, the length of the transition arc segment 433 accounts for too large a proportion, which affects the length proportions of the first arc segment 431 and / or the second arc segment 432, so that the battery may have a corner crack and / or an over-thickness. The above settings can ensure the length proportions of the first arc segment 431 and / or the second arc segment 432, so that the membrane shell of the battery is less likely to have a depression and the depression caused by the edge portion 430 is less likely to cause the battery to have an over-thickness, and the membrane shell is less likely to have a wrinkle. Preferably, the length of the transition arc segment 433 accounts for 8%-22% of the length of the edge portion 430, and the battery is less likely to have an over-thickness or a corner crack.

[0122] In one embodiment, as shown in FIG. 4A, the length of the first arc segment 431 relative to the two ends of the second arc segment 432 along the length direction of the edge portion 430 is the same. Figure 10

[0123] Specifically, the length of the two second arc segments 432 of the edge portion 430 is the same, i.e., W1=W5 and H1=H5. Those skilled in the art can understand that during the cycle of the battery, the cells of the battery expand synchronously at the position of the edge 401. The above setting can make the pressing force of the cells on the two second arc segments 432 of the edge portion 430 consistent, which is conducive to ensuring the structural integrity and electrochemical performance of the battery. Moreover, the above setting is conducive to making the two corner positions of the film shell on both sides of the first arc segment 431 not prone to damage (corner cracking).

[0124] In one embodiment, as shown in FIG. 4A, the length of the first arc segment 431 relative to the two ends of the second arc segment 432 along the length direction of the edge portion 430 is the same. Figure 6 The length of the two transition arc segments 433 of the edge portion 430 is the same. The above setting can make the pressing force of the cells on the two transition arc segments 433 of the edge portion 430 consistent, which is conducive to ensuring the structural integrity and electrochemical performance of the battery.

[0125] In one possible implementation, the length of the two second arc segments 432 of the edge portion 430 is the same, and the length of the two transition arc segments 433 of the edge portion 430 is the same. The above setting can make the first arc segment 431 of the edge portion 430 located at the central position of the edge portion 430, which is conducive to reliably avoiding the film shell from being concave.

[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 in the punched area of the film shell material will be stretched.

[0127] The thickness of the aluminum layer of the film shell at the position of the first arc segment 431 is greater than the thickness of the aluminum layer of the film shell at the position of the transition arc segment 433. Specifically, after the film shell material is punched, the stretching degree of the aluminum layer of the film shell corresponding to the position of the transition arc segment 433 is greater than the stretching degree of the aluminum layer of the film shell material corresponding to the position of the first arc segment 431. The greater the stretching degree of the aluminum layer, the smaller the thickness of the aluminum layer. Therefore, the thickness of the aluminum layer of the film shell at the position of the first arc segment 431 is greater than the thickness of the aluminum layer of the film shell at the position of the transition arc segment 433. The cross section of the film shell at the position of the first arc segment 431 and the cross section of the film shell at the position of the transition arc segment 433 can be obtained by cutting the film shell at the position of the first arc segment 431 and the position of the transition arc segment 433, respectively. The thickness of the aluminum layer at the position of the first arc segment 431 and the position of the transition arc segment 433 of the film shell can be obtained by a 3D microscope.

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

[0129] As can be understood by those skilled in the art, the deformation amount of the film shell material at the position of the transition arc segment 433 is greater than that at the position of the first arc segment 431, and the rib 430 at the position of the first arc segment 431 can be more closely attached to the battery cell, so that the battery is less likely to have a film shell depression and a rib 430 near the depression position during the cycle process.

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

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

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

[0133] As can be understood by those skilled in the art, the deformation amount of the film shell material at the position of the transition arc segment 433 is less than that at the position of 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 film shell of the battery is less likely to have a corner crack during the long cycle process.

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

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

[0136] The battery provided by the application can ensure the energy density of the battery, because the above-mentioned film shell is used, and the battery is less likely to have a film shell depression and a rib 430 near the depression position during the cycle process.

[0137] In one embodiment, as Figure 7 , Figure 10 , Figure 11 andFigure 6 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. Wherein, the extension direction of the tab of the battery cell in the cavity 300 is parallel to the first direction, that is, the tab of the battery cell extends out of the cavity 300 along the first direction. The second direction is perpendicular to the first direction. For example, 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 in the figure, Figure 10 and Figure 11 As shown, the cavity 300 can have two first edge portions 434 and two second edge portions 435, the two first edge portions 434 are arranged opposite to each other along the first direction, and the two second edge portions 435 are arranged opposite to each other along the 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 end point and a fourth end point in the cross section perpendicular to the length direction of the second arc segment 432. Along the depth direction of the cavity 300, the third end point and the fourth end point have a third distance therebetween. Along the preset direction, the third end point and the fourth end point have a fourth distance therebetween. The transition arc segment 433 has a fifth end point and a sixth end point in the cross section perpendicular to the length direction of the transition arc segment 433. Along the depth direction of the cavity 300, the fifth end point and the sixth end point have a fifth distance therebetween. Along the preset direction, the fifth end point and the sixth end point have a sixth distance therebetween.

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

[0140] When the size a1 of the first distance is greater than 3mm, the first arc segment 431 of the first edge portion 434 can interfere with the battery cell, affecting the entry of the battery cell into the shell. When the size a1 of the first distance is less than 1.2mm, the gap between the first arc segment 431 of the first edge portion 434 and the battery cell is large, and the shell can be concave, causing the edge portion 430 to be raised. By setting the size of the first distance, the battery cell can be smoothly entered into the shell, and the shell is not easy to be concave, causing the edge portion 430 to be raised and the battery to be too thick. Preferably, 1.5mm≤a1≤2.5mm, which is further convenient for the entry of the battery cell into the shell while avoiding the battery being too thick.

[0141] As shown in the figure, Figure 11As shown, on the first edge 434, the dimension b1 of the second distance is 0.4mm-1.2mm. For example, the size of b1 can be 0.4mm, 0.6mm, 0.8mm, 1mm or 1.2mm, etc., and is not limited to a single value here.

[0142] When the second distance b1 is greater than 1.2 mm, the first arc segment 431 of the first ridge 434 may interfere with the battery cell, affecting the insertion of the battery cell into the casing. When the second distance b1 is less than 0.4 mm, the gap between the first arc segment 431 of the first ridge 434 and the battery cell is large, and the casing may dent, causing the ridge 430 to warp. In other words, by setting the second distance b1 of the first ridge 434, the battery cell can be smoothly inserted into the casing, and the casing is less likely to dent, causing the ridge 430 to warp and resulting in an excessively thick battery. Preferably, 0.6 mm ≤ b1 ≤ 1.0 mm, further facilitating the insertion of the battery cell into the casing while avoiding an excessively thick battery.

[0143] like Figure 11 As shown, the dimension r1 of the third distance on the first ridge 434 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 to a single value. When r1<0.4mm, the radius of the arc of the second arc segment 432 of the first ridge 434 is small, and the membrane shell is prone to breakage at the position of the second arc segment 432 of the first ridge 434 during the stamping process of the cavity 300. When r1>1.2mm, the gap between the second arc segment 432 of the first ridge 434 and the battery cell is small, and the battery may crack at the corner. In other words, through the above settings, the breakage of the second arc segment 432 of the first ridge 434 during the processing can be avoided, and the battery is less prone to corner cracking. Preferably, 0.6mm≤r1≤1.0mm further avoids damage to the second arc segment 432 of the first ridge 434 during processing, and also makes the battery less prone to corner cracks.

[0144] like Figure 7 As shown, on the first ridge 434, the dimension 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., and is not limited to a single value. The above setting can avoid damage to the second arc segment 432 of the first ridge 434 during processing, and at the same time make the battery less prone to corner cracks. Preferably, 0.6mm≤r2≤1.0mm.

[0145] Illustratively, the first edge portion 434, the fifth distance R1 is 0.4mm-1.2mm, i.e. 0.4mm≤R1≤1.2mm. In 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<0.4mm, a clear edge will appear between the transition arc segment 433 and the second arc segment 432 on the bottom wall 410 of the cavity 300, and the membrane shell is prone to wrinkle between the transition arc segment 433 and the second arc segment 432 of the edge portion 430. When R1>1.2mm, a clear edge will appear between the transition arc segment 433 and the first arc segment 431 on the bottom wall 410 of the cavity 300, and the membrane shell is prone to wrinkle between the transition arc segment 433 and the first arc segment 431 of the edge portion 430. The above setting can avoid a clear edge between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432, and the membrane shell is not prone to wrinkle between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432 of the edge portion 430.

[0146] Illustratively, the first edge portion 434, the sixth distance R2 is 0.4mm-1.2mm, i.e. 0.4mm≤R2≤1.2mm. In 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<0.4mm, a clear edge will appear between the transition arc segment 433 and the second arc segment 432 on the side wall 420 of the cavity 300, and the membrane shell is prone to wrinkle between the transition arc segment 433 and the second arc segment 432 of the edge portion 430. When R2>1.2mm, a clear edge will appear between the transition arc segment 433 and the first arc segment 431 on the side wall 420 of the cavity 300, and the membrane shell is prone to wrinkle between the transition arc segment 433 and the first arc segment 431 of the edge portion 430. The above setting can avoid a clear edge between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432, and the membrane shell is not prone to wrinkle between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432 of the edge portion 430.

[0147] In a possible implementation, the battery cell includes a bending segment, the bending segment of the battery cell is located on 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 segments on opposite sides of the battery cell in the second direction. Specifically, the battery cell is a winding type battery cell, which is formed by stacking and winding a positive electrode sheet, a separator and a negative electrode sheet, and includes two opposite bending segments and a flat segment between the two bending segments.

[0148] As Figure 10 , Figure 12 and Figure 7As shown, the dimension of the first distance on the second ridge 435 is a2, which satisfies: T / 2+B≤a2≤T, 0.5mm≤B≤2T / 5, where T is the thickness of the battery cell. Since the position of the second ridge 435 is opposite to the bent section of the battery cell, the dimension of the first distance on the second ridge 435 is set according to the thickness of the battery cell. B is a radius adjustment value, which can be adjusted 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 ridge 435 and the battery cell is large, and the membrane shell may dent, causing the second ridge 435 to warp and resulting in an excessively thick battery. When a2>T, the first arc segment 431 of the second ridge 435 may interfere with the battery cell, affecting the insertion of the battery cell into the casing. The above design makes it less likely for the second ridge 435 to warp, leading to an excessively thick battery, and allows the battery cell to be smoothly inserted into the casing. Preferably, T / 2+B≤a2≤3T / 4, the above setting makes the second ridge 435 less likely to warp and the battery cell can be inserted into the casing more smoothly.

[0149] like Figure 10 , Figure 12 and Figure 7 As shown, the second distance on the second ridge 435 is dimension b2, where 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 ridge 435 and the battery cell is large, and the membrane shell may dent, causing the second ridge 435 to warp and resulting in an excessively thick battery. When b2>T / 2, the first arc segment 431 of the second ridge 435 may interfere with the battery cell, affecting the insertion of the battery cell into the casing. By setting the dimension of the second distance on the second ridge 435, the second ridge 435 is less likely to warp, leading to an excessively thick battery, and the battery cell can be inserted into the casing smoothly. Preferably, T / 2-0.5≤b2≤T / 2, the second ridge 435 is even less likely to warp, and the battery cell can be inserted into the casing more smoothly.

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

[0151] That is to say, the third distance size r3 of the second arc segment 432 on the second ridge portion 435 is set according to the thickness of the battery cell. When r3 < T / 2-A, the radius of the circular arc of the second arc segment 432 of the second ridge portion 435 is small, and the film shell is prone to damage at the position of the second arc segment 432 of the second ridge portion 435 in the process of machining the cavity 300 by stamping; when r3 > T / 2, the gap between the second arc segment 432 of the second ridge portion 435 and the battery cell is small, and the battery is prone to corner cracking. That is to say, through the above setting, the second arc segment 432 of the second ridge portion 435 can be prevented from being damaged in the machining process, and at the same time, the battery is less prone to corner cracking. Preferably, the radius r3 of the circular arc 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 ridge portion 435 from being damaged in the machining process, and at the same time, the battery is less prone to corner cracking.

[0152] When the battery cell is a wound battery cell, the fourth distance size on the second ridge portion 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. According to the thickness T of the battery cell, the size r4 of the fourth distance can be set to prevent the second arc segment 432 of the second ridge portion 435 from being damaged in the machining process, and at the same time, the battery is less prone to corner cracking. Preferably, T / 2-0.5 ≤ r4 ≤ T / 2.

[0153] When the battery cell is a wound battery cell, the fifth distance size on the second ridge portion 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. Wherein, R3 gradually increases from the direction of 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 obvious ridges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432, so that the second ridge portion 435 is less prone to wrinkles.

[0154] When the battery cell is a wound battery cell, the sixth distance size on the second ridge portion 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. Wherein, R4 gradually increases from the direction of 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 obvious ridges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432, so that the second ridge portion 435 is less prone to wrinkles.

[0155] In another possible implementation, the battery cell is a jelly-roll battery cell, and the second edge 435 is arranged opposite to an edge of the battery cell in the second direction. Specifically, the jelly-roll battery cell is formed by interleaving and stacking a plurality of positive electrode sheets, a plurality of negative electrode sheets, and separators.

[0156] When the cavity 300 is used to accommodate the jelly-roll battery cell, the size a2 of the first distance on the second edge 435 is 1.2 mm-3 mm, i.e., 1.2 mm≤a2≤3 mm. Illustratively, when the cavity 300 is used to accommodate the jelly-roll battery cell, the cross-sectional shape and size of the first arc segment 431 of the second edge 435 are the same as those of the first arc segment 431 of the first edge 434. The size a2 of the first distance on the second edge 435 makes the second edge 435 less likely to be warped to cause the battery to be excessively thick, and the battery cell can be smoothly accommodated in the cavity 300.

[0157] When the cavity 300 is used to accommodate the jelly-roll battery cell, the size b2 of the second distance on the second edge 435 is 0.4 mm-1.2 mm. The size b2 of the second distance on the second edge 435 makes the second edge 435 less likely to be warped to cause the battery to be excessively thick, and the battery cell can be smoothly accommodated in the cavity 300.

[0158] When the cavity 300 is used to accommodate the jelly-roll battery cell, the size r3 of the third distance on the second edge 435 is 0.4 mm-1.2 mm, i.e., 0.4 mm≤r3≤1.2 mm. By setting the size 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 less likely to be cracked.

[0159] When the cavity 300 is used to accommodate the jelly-roll battery cell, the size r4 of the fourth distance on the second edge 435 is 0.4 mm-1.2 mm, i.e., 0.4 mm≤r4≤1.2 mm. By setting the size r4 of the fourth 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 less likely to be cracked.

[0160] When the cavity 300 is used to accommodate the jelly-roll battery cell, the size R3 of the fifth distance on the second edge 435 is 0.4 mm-1.2 mm, i.e., 0.4 mm≤R3≤1.2 mm. The above setting can prevent the transition arc segment 433 on the second edge 435 from having a clear edge between the first arc segment 431 or the second arc segment 432, so that the second edge 435 is less likely to be wrinkled.

[0161] When the cavity 300 is used to accommodate the laminated battery cell, the size of the sixth distance R4 on the second edge portion 435 is 0.4mm-1.2mm, i.e. 0.4mm≤R4≤1.2mm. The above setting can avoid the occurrence of obvious edges between the transition arc segment 433 and the first arc segment 431 or the second arc segment 432 on the second edge portion 435, thereby avoiding the occurrence of wrinkles on the second edge portion 435.

[0162] As shown in Figure 9 , Figure 11 and Figure 7 , the size of the third distance on the same second arc segment 432 is equal to the size of the fourth distance. For example, the cross section of the second arc segment 432 in the length direction of itself is a circular arc, and the circular 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 equal to the radius of the circular arc, respectively. Through the above setting, it is convenient to set the arc surface of the convex mold, thereby facilitating the setting of the second arc segment 432.

[0163] As shown in Figure 11 and Figure 12 , the size of the fifth distance on the same transition arc segment 433 is equal to the size of the sixth distance. For example, the cross section of the transition arc segment 433 in the length direction of itself is a circular arc, and the circular 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 equal to the radius of the circular arc, respectively. Through the above setting, it is convenient to set the arc surface of the convex mold, thereby facilitating the setting of the transition arc segment 433.

[0164] As shown in ​ , the intersection line of the edge portion 430 and the bottom wall 410 is a line segment M (composed of line segments M1-M5), and the intersection line of the edge portion 430 and the side wall 420 is a line segment N (composed of line segments N1-N5). The distance from M1-M5 to the reference plane (the plane where the opening of the cavity 300 is located) is equal to the depth D of the cavity 300, the distance from N1 and N5 to the reference plane is D-r (the difference between the depth of the cavity 300 and the third distance), the distance from N2 and N4 to the reference plane is D-R (the difference between the depth of the cavity 300 and the fifth distance), and the distance from N3 to the reference plane is D-a (the difference between the depth of the cavity 300 and the first distance).

[0165] Hereinafter, the film shell and the battery of the present application will be described in detail through specific embodiments. The specific differences of the following batteries are shown in Tables 1 and 2.

[0166] Example 1

[0167] 1. Preparation of positive electrode sheet:

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

[0169] The preparation method of the positive active material coating is as follows: the conductive agent and the PVDF glue solution are uniformly mixed, then the lithium cobaltate is added and stirred uniformly to obtain the positive active material layer slurry.

[0170] The positive active material layer is composed of 97.6 parts by mass of lithium cobaltate, 1.05 parts by mass of PVDF, and 1.35 parts by mass of 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] The negative electrode slurry is prepared, the negative electrode slurry is coated on the carbon-coated copper foil, and the negative electrode sheet is obtained after baking, rolling, and slitting.

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

[0174] 3. Preparation of battery cell:

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

[0176] 4. Preparation of film shell:

[0177] The aluminum plastic film is punched to obtain the first shell 100 and the second shell 200, the first shell 100 has a cavity 300, the cavity 300 has four edge portions 430, each edge portion 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 at the middle of the corresponding edge portion 430, the two second arc segments 432 are respectively located at the two ends of the corresponding edge portion 430, and 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 end point and a second end point in a cross section perpendicular to the length direction of the first arc segment 431. The first distance is between the first end point and the second end point along the depth direction of the cavity 300. The second distance is between the first end point and the second end point along the preset direction, which is perpendicular to the depth direction of the cavity 300 and the length direction of the edge portion 430. The second arc segment 432 has a third end point and a fourth end point in a cross section perpendicular to the length direction of the second arc segment 432. The third distance is between the third end point and the fourth end point along the depth direction of the cavity 300. The fourth distance is between the third end point and the fourth end point along the preset direction. The transition arc segment 433 has a fifth end point and a sixth end point in a cross section perpendicular to the length direction of the transition arc segment 433. The fifth distance is between the fifth end point and the sixth end point along the depth direction of the cavity 300. The sixth distance is between the fifth end point and the sixth end point along the preset direction.

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

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

[0181] 5. Assembly:

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

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

[0184] Among them, the active material of the positive active material layer includes one or more of lithium cobaltate, lithium iron phosphate, lithium nickel cobalt manganese, lithium nickel cobalt aluminum, lithium manganate and lithium-rich manganese-based lithium.

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

[0186] The positive electrode adhesive is mainly a polyvinylidene fluoride (PVDF) adhesive, and the negative electrode adhesive is mainly a butadiene-styrene 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] Examples 2-31

[0189] The difference from Example 1 is that the number of the ribs 430 of the cavity 300 in the film shell (the number of the ribs 430 in Example 30 is two, the two ribs 430 are oppositely arranged along the first direction, and the tabs of the battery cell extend out of the cavity 300 along the first direction; the number of the ribs 430 in Example 31 is one, the rib 430 is located on one side of the cavity 300 along the first direction, and the tabs of the battery cell extend out of the cavity 300 along the first direction), the first distance, the second distance, the length ratio of the first arc segment 431 in the corresponding rib 430, the third distance, the fourth distance, the length ratio of the second arc segment 432 in the corresponding rib 430, the fifth distance, the sixth distance, and the length ratio of the transition arc segment 433 in the corresponding rib 430 of each rib 430 are different, and specific conditions are shown in Tables 1 and 2. In addition to the differences shown in Table 1, the remaining conditions are the same as those in Example 1.

[0190] Example 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 ribs 434 and two second ribs 435, the two first ribs 434 are oppositely arranged along the first direction, the two second ribs 435 are oppositely arranged along the second direction, and the tabs of the battery cell extend out of the cavity 300 along the first direction. Each first rib 434 and each second rib 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 length ratio of the first arc segment 431 to the corresponding first edge portion 434 is 35%. 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 length ratio of the second arc segment 432 to the corresponding first edge portion 434 is 20%. 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, and 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, and the minimum value of the sixth distance is 0.8 mm, and the maximum value of the sixth distance is 1 mm. The length ratio of the transition arc segment 433 to the corresponding first edge portion 434 is 10%.

[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 length ratio of the first arc segment 431 to the corresponding second edge portion 435 is 35%. 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 length ratio of the second arc segment 432 to the corresponding second edge portion 435 is 20%. 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, and 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, and the minimum value of the sixth distance is 2 mm, and the maximum value of the sixth distance is 2.5 mm. The length ratio of the transition arc segment 433 to the corresponding second edge portion 435 is 10%.

[0195] Examples 33-40

[0196] The difference from Example 32 is that the first distance, the second distance of the first arc segment 431 of each second edge portion 435, the third distance, the fourth distance of the second arc segment 432 of each second edge portion 435, the fifth distance, and the sixth distance of the transition arc segment 433 of each second edge portion 435 are different, and specific conditions are shown in Table 1 and Table 2. In addition to the differences shown in Table 1, the remaining conditions are the same as those in Example 1.

[0197] Comparative Example 1

[0198] The difference from Example 1 is that the edge of the cavity 300 is a circular arc segment with a circular arc radius of 0.4 mm (without setting a circular arc segment with a different circular arc radius). The remaining conditions are the same as those in Example 1.

[0199] Comparative Example 2

[0200] The difference from Example 1 is that the first distance of the first arc segment 431 of each ridge portion 430 is 2 mm, and the second distance is 2 mm. The third distance of the second arc segment 432 of each ridge 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 ridge portion 430 gradually increases from the direction of the second arc segment 432 to the first arc segment 431, and 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 ridge portion 430 gradually increases from the direction of the second arc segment 432 to the first arc segment 431, and 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 ridge portion 430 is 0.8 mm, and the second distance is 2 mm. The third distance of the second arc segment 432 of each ridge 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 ridge portion 430 gradually increases from the direction of the second arc segment 432 to the first arc segment 431, and 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 ridge portion 430 gradually increases from the direction of the second arc segment 432 to the first arc segment 431, and 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 related performances of the batteries in the above examples and comparative examples were tested, and the test results are recorded in Table 3, and the test methods are as follows:

[0211] 1. 25℃ cycle test: charge to 4.5V at 1.5C rate and then discharge to 3.0V at 0.5C rate at 25℃; follow the process to perform charge-discharge cycle, detect the cycle number of lithium ion battery when edge lifting occurs, or detect whether edge lifting occurs after 1200 cycles of lithium ion battery, and detect whether corner cracking occurs after 1000 cycles of battery, or detect the cycle number when corner cracking occurs.

[0212] 2. 45℃ cycle test: charge to 4.5V at 1.8C rate and then discharge to 3.0V at 0.8C rate at 45℃; follow the process to perform charge-discharge cycle, detect the cycle number of lithium ion battery when edge lifting occurs, or detect whether edge lifting occurs after 1200 cycles of lithium ion battery, and detect whether corner cracking occurs after 800 cycles of battery, or detect the cycle number when corner cracking occurs.

[0213] Wherein, the edge lifting refers to the lifting part beyond the outer side of the bottom wall 410 in the thickness direction of the battery, resulting in the battery being too thick.

[0214] 3. After the cell is placed in the cavity 300 of the film shell and the battery is made, the appearance of the battery is observed to detect the area of the film shell where the wrinkle occurs. When the wrinkle area is not more than 2mm 2 , it indicates that the cell shell process is normal; when the wrinkle area is more than 2mm 2 but not more than 4mm 2 , it indicates that the cell shell process is slightly difficult; when the wrinkle area is more than 4mm 2 , it indicates that the cell shell process is difficult.

[0215] Table 3:

[0216]

[0217]

[0218] Compared with Comparative Examples 1-3, in Examples 1-31, the edge part 430 of the film shell is designed with different arc segments, the edge part 430 includes a first arc segment 431, two second arc segments 432 located at both ends of the edge part 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 problem of battery film shell lifting and improve the cycle life of the battery.

[0219] Further, compared with Embodiment 1 and Embodiment 5, Embodiments 2-4 control the first distance of the first arc segment 431 of each ridge portion 430 to be in the range of 1.2mm-3mm, which is beneficial to solve the problem of battery film shell buckling while the folding area of the film shell is small, which is convenient for the cell to enter the shell while ensuring the appearance of the battery.

[0220] Further, compared with Embodiment 6 and Embodiment 10, Embodiments 7-9 control the second distance of the first arc segment 431 of each ridge portion 430 to be in the range of 0.4mm-1.2mm, which is beneficial to solve the problem of battery film shell buckling while the folding area of the film shell is small, which is convenient for the cell to enter the shell while ensuring the appearance of the battery.

[0221] Embodiments 11-14 show that by controlling the third distance and the fourth distance of the second arc segment 432 of each ridge portion 430 to be in the range of 0.4mm-1.2mm, it is beneficial to solve the problem of battery film shell buckling and corner cracking while the folding area of the film shell is small, which is convenient for the cell to enter the shell while ensuring the appearance of the battery.

[0222] Further, compared with Embodiment 15 and Embodiment 19, Embodiments 16-18 control the ratio of the length of the first arc segment 431 to the length of the ridge portion 430 to be 30%-70%, which takes into account the improvement of the corner cracking and buckling problems of the battery film shell, improves the cycle life of the battery, and the folding area of the film shell is small, which is convenient for the cell to enter the shell while ensuring the appearance of the battery.

[0223] Further, compared with Embodiment 20 and Embodiment 24, Embodiments 21-23 control the ratio of the length of the second arc segment 432 to the length of the ridge portion 430 to be 5%-30%, which takes into account the improvement of the corner cracking and buckling problems of the battery film shell, improves the cycle life of the battery, and the folding area of the film shell is small, which is convenient for the cell to enter the shell while ensuring the appearance of the battery.

[0224] Further, compared with Embodiment 25 and Embodiment 29, Embodiments 26-28 control the ratio of the length of the transition arc segment 433 to the length of the ridge portion 430 to be 5%-25%, which takes into account the improvement of the corner cracking and buckling problems of the battery film shell, improves the cycle life of the battery, and the folding area of the film shell is small, which is convenient for the cell to enter the shell while ensuring the appearance of the battery.

[0225] Further, compared with Embodiment 12, Embodiment 30 and Embodiment 31, the more the number of ridge portions 430, the better the improvement of the battery film shell buckling problem, and after increasing the number of ridge portions 430, the folding area of the film shell can be reduced, which is more convenient for the cell to enter the shell and ensures the appearance of the battery.

[0226] It can be concluded from Examples 32 to 34 that when the battery cell is a winding cell, by controlling the first distance of the first arc segment 431 of each edge portion 430 to be within the range of T / 2+B to T (0.5mm≤B≤2T / 5), the problems of corner cracking and warping of the battery film shell can be improved, the wrinkle area of the film shell is small, the cell is facilitated to enter the shell, and the appearance of the battery can be ensured.

[0227] It can be concluded from Examples 35 to 37 that when the battery cell is a winding cell, by controlling the second distance of the first arc segment 431 of each edge portion 430 to be within the range of T / 2-A to T / 2 (0.5mm≤A≤2T / 5), the problems of corner cracking and warping of the battery film shell can be improved, the cycle life of the battery is improved, the wrinkle area of the film shell is small, the cell is facilitated to enter the shell, and the appearance of the battery can be ensured.

[0228] It can be concluded from Examples 38 to 40 that when the battery cell is a winding cell, by controlling the third distance and the fourth distance of the first arc segment 431 of each edge portion 430 to be within the range of T / 2-A to T / 2 (0.5mm≤A≤2T / 5) respectively, the problems of corner cracking and warping of the battery film shell can be improved, the cycle life of the battery is improved, the wrinkle area of the film shell is small, the cell is facilitated to enter the shell, and the appearance of the battery can be ensured.

[0229] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A film can of a pouch battery, characterized by, The membrane shell is provided with a cavity (300), the cavity (300) comprises a bottom wall (410), a side wall (420) provided around the bottom wall (410), and a rib (430) connected between the bottom wall (410) and the side wall (420); Along the length direction of the rib (430), the rib (430) comprises a first arc segment (431), a second arc segment (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); The first arc segment (431) has a first end point and a second end point in a cross section perpendicular to the length direction of the first arc segment (431), the first end point is connected with the bottom wall (410), and the second end point is connected with the side wall (420); Along the depth direction of the cavity (300), the first distance between the first end point and the second end point is greater than the second distance between the first end point and the second end point along a preset direction, the preset direction is perpendicular to the depth direction of the cavity (300) and the length direction of the rib (430) respectively. The size of the first distance is greater than the size of the second distance.

2. The membrane housing of claim 1, wherein, The second arc segment (432) has a third end point and a fourth end point in a cross section perpendicular to the length direction of the second arc segment (432), the third end point is connected with the bottom wall (410), and the fourth end point is connected with the side wall (420); Along the depth direction of the cavity (300), the third distance between the third end point and the fourth end point is less than or equal to the size of the second distance; along the preset direction, the fourth distance between the third end point and the fourth end point is less than or equal to the size of the second distance. The size of the third distance and the size of the fourth distance are less than or equal to the size of the second distance.

3. The membrane housing of claim 2, wherein, The fifth end point and the sixth end point of the transition arc segment (433) are connected with the bottom wall (410) and the side wall (420) respectively in a cross section perpendicular to the length direction of the transition arc segment (433); Along the depth direction of the cavity (300), the fifth distance between the fifth end point and the sixth end point is between the third distance and the second distance; along the preset direction, the sixth distance between the fifth end point and the sixth end point is between the fourth distance and the second distance. The first arc segment (431) is tangent to the bottom wall (410) and the side wall (420) respectively; 4. The membrane housing of claim 2, wherein, 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. Along the length direction of the rib (430), the length of the first arc segment (431) is 30%-70% of the length of the rib (430); and / or, 5. The membrane housing of claim 2, wherein, ​ Along the length direction of the edge (430), the ratio of the length of the second arc segment (432) to the length of the edge (430) is 5%-30%; And / or, Along the length direction of the edge (430), the ratio of the length of the transition arc segment (433) to the length of the edge (430) is 5%-25%.

6. The membrane housing according to any one of claims 1-5, wherein, The membrane shell includes a first shell (100) and a second shell (200), with the first shell (100) covering the second shell (200); At least one of the first housing (100) and the second housing (200) is provided with the cavity (300) and has the bottom wall (410), the side wall (420) and the ridge (430) connecting the bottom wall (410) and the side wall (420).

7. The membrane housing according to any one of claims 1-5, wherein, Along the length direction of the ridge (430), the first arc segment (431) has the same length as the second arc segment (432) at both ends; And / or, along the length direction of the ridge (430), the first arc segment (431) has the same length as the transition arc segments (433) at both ends.

8. The membrane housing according to any one of claims 1-5, wherein, The membrane shell includes an aluminum layer; the thickness of the aluminum layer at the first arc segment (431) is greater than the thickness of the aluminum layer 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) position is greater than the thickness of the aluminum layer of the membrane shell at the second arc segment (432) position.

9. A battery, characterized by It includes a battery cell and a membrane housing as described in any one of claims 1-8, wherein the battery cell is disposed in a cavity (300) of the membrane housing.

10. The battery of claim 9, wherein, The ridge portion includes a first ridge portion (434) and a second ridge portion (435). The first ridge portion (434) is located at the end of the cavity along a first direction, and the first ridge portion (434) is disposed opposite to the edge of the battery cell in the first direction. Both the first ridge (434) and the second ridge (435) 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 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. On the first ridge (434), the dimension of the first distance is 1.2mm-3mm; and / or, On the first ridge (434), the dimension of the second distance is 0.4mm-1.2mm; and / or, On the first ridge (434), the dimension of the third distance is 0.4mm-1.2mm; and / or, The fourth distance on the first edge (434) is 0.4mm-1.2mm; and / or, The fifth distance on the first edge (434) is 0.4mm-1.2mm; and / or, The sixth distance on the first edge (434) is 0.4mm-1.2mm.

11. The battery of claim 10, wherein, The second edge (435) is located on the side of the film shell in the second direction, and the second edge (435) is opposite to the bending section of the battery cell in the second direction; The first distance on the second edge (435) is a2, and the a2 satisfies: T / 2+B≤a2≤T, 0.5mm≤B≤2T / 5, and T is the thickness of the battery cell; and / or, The second distance on the second edge (435) is b2, and the b2 satisfies: T / 2-A≤b2≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell; and / or, The third distance on the second edge (435) is r3, and the r3 satisfies: T / 2-A≤r3≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell; and / or, The fourth distance on the second edge (435) is r4, and the r4 satisfies: T / 2-A≤r4≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell; and / or, The fifth distance on the second edge (435) is R3, and the R3 satisfies: T / 2-A≤R3≤T / 2, 0.5mm≤A≤2T / 5, and T is the thickness of the battery cell; and / or, The sixth distance on the second edge (435) is R4, and the 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 of claim 10, wherein, The battery cell is a laminated battery cell, and the second edge (435) is opposite to the edge of the battery cell in the second direction; The first distance on the second edge (435) is 1.2mm-3mm; and / or, The second distance on the second edge (435) is 0.4mm-1.2mm; and / or, The third distance on the second edge (435) is 0.4mm-1.2mm; and / or, The fourth distance on the second edge (435) is 0.4mm-1.2mm; and / or, The fifth distance on the second edge (435) is 0.4mm-1.2mm; and / or, The sixth distance on the second edge (435) is 0.4mm-1.2mm.

13. The battery of any one of claims 10-12, wherein, 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.

Images