Membrane shell and battery

Abstract

The invention provides a membrane shell and a battery, the membrane shell comprises a first side part, an edge part and a ridge wall connected between the first side part and the edge part, and the plane where the first side part is located intersects with the plane where the edge part is located; the edge wall comprises a first arc section, second arc sections located at the two opposite ends of the first arc section and transition arc sections connected between the first arc section and the second arc sections, and the arc radius R137 of the first arc section is larger than the arc radius R135 of the second arc sections. According to the invention, the problems of battery membrane shell corner cracking, battery membrane shell edge bulge and battery expansion caused by the corner cracking and the battery membrane shell edge bulge can be inhibited.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a membrane shell and a battery. Background Art

[0002] Soft-pack batteries (such as soft-pack lithium-ion batteries) have been widely used in portable electronic devices and electric vehicles due to their high energy density and other characteristics. With the development of science and technology, while pursuing high energy density and long cycle life of batteries, higher and higher requirements are also put forward for battery safety and other performance.

[0003] Soft-pack batteries usually use soft packaging materials (such as aluminum-plastic film) to encapsulate the battery cells. Specifically, a mold core (convex film) is usually used to punch the soft packaging material into a film shell with an inner pit (a cavity for accommodating the battery cell), and the battery cell is placed in the inner pit of the film shell to achieve encapsulation of the battery cell.

[0004] In order to improve the energy density (ED) of the battery, the membrane shell is required to have a smaller size, especially for high ED soft-pack batteries, because their size design is more extreme. During the long cycle of the battery, the membrane shell is easily squeezed and stretched repeatedly due to factors such as cell expansion, causing problems such as corner cracks at the corners of the battery membrane shell, and then allowing water vapor and other components to enter the membrane shell and corrode electrode materials and other materials, causing the battery thickness to expand beyond the standard, internal resistance to increase, inflation and leakage, resulting in battery cycle failure, and even causing safety problems such as combustion and explosion.

[0005] Therefore, how to suppress the cracking of the battery membrane shell corners and the bulging of the battery membrane shell edges and the resulting battery expansion are technical problems that need to be solved urgently in this field. Summary of the invention

[0006] The present invention provides a membrane shell and a battery, which can suppress problems such as cracking of the battery membrane shell corners and bulging of the battery membrane shell edges and battery expansion caused thereby, and effectively overcome the defects of the prior art.

[0007] In one aspect of the present invention, a membrane shell is provided, comprising a first side portion, an edge portion, and an edge wall connected between the first side portion and the edge portion, wherein the edge wall comprises a first arc segment, second arc segments located at opposite ends of the first arc segment, and a transition arc segment connected between the first arc segment and the second arc segment, wherein the arc radius R of the first arc segment is 137 is greater than the radius R of the second arc segment 135 .

[0008] According to one embodiment of the present invention, the ratio of the length of the second arc segment to the length of the prism is 10% to 32%; and / or, the ratio of the length of the transition arc segment to the length of the prism is 5% to 27%; and / or, the ratio of the length of the first arc segment to the length of the prism is 30% to 74%.

[0009] According to one embodiment of the present invention, the arc radius R of the transition arc segment is 136 The radius R of the arc between the second arc segment 135 The arc radius R of the first arc segment 137 and increases along the direction from the second arc segment to the first arc segment.

[0010] According to one embodiment of the present invention, the membrane shell includes the edge located on at least one side of the membrane shell in the first direction, and the edge located on at least one side of the membrane shell in the second direction, each of the edge portions and the first side portion are respectively connected to the edge wall, the first direction intersects with the second direction; the edge wall existing on any side of the membrane shell in the first direction satisfies: 1<R 137 / R 135 ≤8, preferably 1<R 137 / R 135 ≤5; and / or, R 135 0.2 to 1.5 mm, preferably 0.4 to 1 mm; and / or, R 137 0.8 to 5 mm; and / or the arc radius R of the transition arc segment 136 Between 0.2mm and 5mm.

[0011] According to one embodiment of the present invention, the edge wall existing on either side of the membrane shell in the second direction satisfies: 1<R 137 / R 135 ≤5; and / or, R 135 H / 2-A to H / 2+A; and / or, R 137 H / 2-A~H / 2+B; and / or, the arc radius R of the transition arc segment 136 Between H / 2-A and H / 2+B; wherein A is 0.5 to 2H / 5, B is 0.5 to 2H / 5, H is the depth of the cavity of the membrane shell, R 135 , R 136 , R 137 The units of A and H are mm.

[0012] According to one embodiment of the present invention, the membrane shell includes a first main body portion and a second main body portion connected to each other, at least one of the first main body portion and the second main body portion has a cavity, and the first side portion, the edge portion and the edge wall connected between the first side portion and the edge portion that surround the cavity.

[0013] Another aspect of the present invention provides a battery, comprising the above-mentioned membrane shell and a battery cell located in the membrane shell.

[0014] According to one embodiment of the present invention, the battery cell is a laminated battery cell or a wound battery cell.

[0015] According to one embodiment of the present invention, the battery cell comprises a bent portion, the bent portion of the battery cell is located on two opposite sides of the battery cell in the second direction, and the edge wall located on either side of the membrane shell in the second direction satisfies: 1<R 137 / R 135 ≤5; and / or, R 135 T / 2-A~T / 2+A; and / or, R 137 T / 2-A~T / 2+B; and / or, the arc radius R of the transition arc segment 136 Between T / 2-A and T / 2+B; wherein A is 0.5 to 2T / 5, B is 0.5 to 2T / 5, T is the thickness of the battery cell, R 135 , R 136 , R 137 The unit of and T is mm.

[0016] According to one embodiment of the present invention, the edge wall located on any side of the membrane shell in the first direction satisfies: 1<R 137 / R 135 ≤8, preferably 1<R 137 / R 135 ≤5; and / or, R 135 0.2 mm to 1.5 mm, preferably 0.4 to 1 mm; and / or, R 137 is 0.8 mm to 5 mm; and / or the arc radius R of the transition arc segment 136 Between 0.2mm and 5mm.

[0017] The implementation of the present invention has at least the following beneficial effects: in the membrane shell, the intersecting first side portion and the edge portion are connected by an edge wall, the arc radius of the end area (small arc segment) of the edge wall is smaller, the arc radius of the middle area (large arc segment) is larger, and the middle area and the end area are transitioned by a transition arc segment. After the membrane shell is used to encapsulate the battery cell, it is beneficial for the battery cell and the middle area of ​​the edge wall of the membrane shell to have a relatively small gap space, which can avoid the occurrence of the edge wall (edge) of the battery membrane shell being concave, the edge edge near the concave part being warped (convex), and the resulting increase in the battery expansion rate (especially the increase in the thickness expansion rate, causing the battery to be too thick) during the battery cycle process. At the same time, compared with the large arc segment, the small arc segment of the edge wall is close to the corner of the membrane shell, which is beneficial for the battery cell and the membrane shell to have a relatively large gap space at the corner, which can suppress the battery cell from squeezing and stretching the membrane shell due to factors such as battery cell expansion, and the resulting rupture (corner crack) at the corner of the membrane shell. Therefore, the present invention can provide battery safety and cycle life (cycle stability) and other performance, and avoid problems such as battery cycle failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram showing any arc segment of the edge wall of the membrane shell according to an embodiment of the present invention;

[0019] Figure 2 A schematic diagram showing the arc radius of any arc segment of a prism wall in one embodiment of the present invention;

[0020] Figure 3 Schematic diagram of each arc segment of the prism wall in one embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of the structure of the membrane shell before encapsulating the battery cell in one embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of a membrane shell structure of a battery in one embodiment of the present invention;

[0023] Figure 6 A schematic diagram of a battery structure according to an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of a battery cell structure according to an embodiment of the present invention;

[0025] Figure 8 A schematic diagram of a mold core structure according to an embodiment of the present invention;

[0026] Fig. 9 A schematic diagram showing any arc surface of the edge surface of the mold core according to an embodiment of the present invention;

[0027] Fig.10 A schematic diagram showing the arc radius of any arc surface of an edge face in one embodiment of the present invention;

[0028] Description of reference numerals:

[0029] 1: membrane shell; 11: first side; 12: side; 13: prism; 14: second main body; 15: extension; 100: inner pit; 101: first corner; 102: second corner; 103: third corner; 104: fourth corner; 121: first side; 122: second side; 123: third side; 124: fourth side; 131: first prism; 132: second prism; 133: third prism; 134: fourth prism; 135: small arc segment; 136: transition arc segment; 137: large arc segment; 2, battery cell; 211: positive 1. Pole tab; 200: end face of electrode sheet; 221: negative pole tab; 201: straight section; 202: bending section; 3. mold core; 31: main side; 32: side surface; 33: prism; 300: recessed area; 301: first vertex; 302: second vertex; 303: third vertex; 304: fourth vertex; 321: first side surface; 322: second side surface; 331: first prism; 332: second prism; 333: third prism; 334: fourth prism; 335: small arc surface; 336: transition arc surface; 337: large arc surface; L 135 : length of the small arc segment; L 136 : The length of the transition arc; L 137 : length of the large arc segment; L1, L2, L3, L4: tangents; T1, T2, T3, T4: perpendiculars; A, B: circular arc curves; O1, O2: center of the circle; r1, r2: radius; x: first direction; y: second direction; z: third direction. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] like Figure 4 As shown, the membrane shell includes a first main body part and a second main body part 14 that are connected to each other. In the process of using a mold core to punch the membrane shell material into a membrane shell, the mold core is usually placed in the first main body part and / or the second main body part 14 of the membrane shell material to punch out a cavity (or inner pit) 100 in the first main body part and / or the second main body part 14 to obtain the membrane shell.

[0032] The following is a specific description using the process of punching out the cavity 100 in the first main body as an example. The process of punching out the cavity 100 in the second main body 14 and packaging the battery cell is similar and will not be described in detail.

[0033] The mold core is placed in the first main body of the membrane shell material, and the main side of the mold core faces the first main body of the membrane shell material. Then, the first main body of the membrane shell material is pressed by the mold core, and a cavity 100 is punched out in the first main body of the membrane shell material. At this time, the first main body is surrounded by the cavity 100; then, the battery cell is placed in the cavity 100 surrounded by the first main body of the membrane shell, and then the second main body 14 is covered at the opening of the cavity 100 and connected to the first main body, thereby closing the cavity 100 and realizing the packaging of the battery cell.

[0034] Specifically, the film shell after encapsulating the battery cell includes a first main body portion and a second main body portion 14, the first main body portion includes a first side portion 11 and an edge portion 12 that are connected to each other, so that the first main body portion is enclosed to form a cavity 100; after encapsulating the battery cell, the second main body portion 14 covers the cavity 100 and is connected to the edge portion 12, thereby closing the cavity 100 (the first side portion 11 is located on one side in the depth direction of the cavity 100, the second main body portion 14 is located on the other side in the depth direction of the cavity 100, and the edge portion 12 is located on the peripheral side of the cavity 100).

[0035] like Figure 4 As shown, the membrane shell 1 generally includes a plurality of side portions 12 , which are distributed along the circumference of the first main body portion of the membrane shell 1 , and two adjacent side portions 12 are connected to each other and intersect with the first side portion 11 to form a corner portion of the membrane shell 1 .

[0036] Continue to refer Figure 4 The connection portion between the first side portion 11 and the edge portion 12 forms an edge, and the cross section of the edge perpendicular to the length direction of the edge can generally be an arc surface, that is, the first side portion 11 transitions to the edge portion 12 through the arc-shaped edge.

[0037] According to the inventor's research, when the entire edge is set with a fixed radius (that is, the radius of the arc surface in each area of ​​the entire edge is basically equal) (correspondingly, the edge surface 33 in the mold core 3 corresponding to the edge of the membrane shell 1 is also set with a fixed radius), it is difficult to take into account both the corner crack problem and the edge warping problem of the battery membrane shell 1.

[0038] Specifically, increasing the gap between the battery cell and the membrane shell is a common method to improve the corner cracking of the battery membrane shell. For example, when using a mold core to punch the flexible packaging film into a membrane shell, the difference between the width of the punch and the width of the battery cell (P-JR GAP)) and the difference between the length of the punch and the width of the widest electrode sheet in the battery cell (usually the width of the negative electrode sheet) (PA GAP)) are increased to correspondingly increase the gap between the battery cell and the membrane shell in the width direction and the gap between the battery cell and the membrane shell in the length direction. However, the gap space between the battery cell and the membrane shell becomes larger, making the surrounding side of the battery cell empty, which not only reduces the energy density of the battery, but also during the long cycle of the battery, the edges of the battery membrane shell (such as the edges of the side edges of the membrane shell (side edges), the top edge and the bottom edge) are easily concave due to factors such as atmospheric pressure. At the same time, the edges close to the concave part are warped, causing a sudden increase in battery expansion (especially a sudden increase in thickness expansion, resulting in an excessively thick battery), causing battery failure and other problems.

[0039] Although the periphery of the battery membrane shell is reshaped by means of a clamp or other components (for example, a clamp is used to press the convex membrane shell in the direction toward the battery cell to reduce the thickness and other dimensions of the battery), the effect of improving the battery expansion is limited. The edges of the shaped membrane shell are prone to rebound and bulge again, causing the battery cycle expansion to exceed the standard, leading to battery failure. At the same time, in the process of reshaping the periphery of the battery membrane shell, the membrane shell and components such as the battery cell located inside the membrane shell are easily damaged, such as damaging the electrode sheets (positive sheet, negative sheet), affecting the battery performance.

[0040] Therefore, when the gap between the battery cell 2 and the membrane shell 1 is small (for example, the P-JR GAP and the PA GAP are reduced), although the problem of the edges being sunken during the battery cycle and the edges being bulged near the sunken parts can be suppressed to a certain extent, the corners of the battery membrane shell 1 (that is, the corners formed by the intersection of the first side portion 11 and the edge portion 12 in the first main body of the membrane shell 1, which usually have four corners (four corners)) are easily squeezed by the battery cell 2 and cracked, resulting in battery cycle failure and battery safety problems; and when the gap between the battery cell 2 and the membrane shell 1 is large (for example, the P-JR GAP and the PA GAP are increased), the battery cell 2 and the membrane shell 1 are easily sunken. Although the corner crack problem of the battery membrane shell 1 can be suppressed to a certain extent, the edges of the battery membrane shell 1 are easily concave (concave toward the cavity 100 (i.e. concave toward the inside of the membrane shell 1)) due to factors such as atmospheric pressure, and the edges close to the concave parts are raised (the edges are raised toward the outside of the membrane shell 1), causing a sudden increase in battery expansion (especially a sudden increase in thickness expansion, resulting in an excessively thick battery), causing battery failure and other problems.

[0041] In view of this, an embodiment of the present invention provides a mold shell, such as Figures 1 to 5As shown, the membrane shell 1 includes a first side portion 11, an edge portion 12, and an edge wall 13 connected between the first side portion 11 and the edge portion 12; the plane where the first side portion 11 is located intersects with the plane where the edge portion 12 is located; the edge wall 13 includes a first arc segment 137, a second arc segment 135 located at opposite ends of the first arc segment 137, and a transition arc segment 136 connected between the first arc segment 137 and the second arc segment 135; the arc radius R of the first arc segment 137 137 Greater than the arc radius R of the second arc segment 135 135 .

[0042] Thus, in the above-mentioned membrane shell 1, the intersecting first side portion 11 and the edge portion 12 are connected by the ridge wall 13, and different areas of the ridge wall 13 have different arc radii (the arc radius of the end area (the second arc segment 135) is smaller, and the arc radius of the middle area (the first arc segment 137) is larger, and the middle area and the end area are transitioned by the transition arc segment 136). After the membrane shell 1 is used to encapsulate the battery cell 2, it is beneficial for the battery cell 2 and the middle area of ​​the ridge wall 13 of the membrane shell 1 to have a relatively small gap space, which can avoid the battery membrane shell 1 from occurring during the battery cycle and the like. The edges (edge ​​walls 13) are sunken, the edges near the sunken parts are warped (convex), and the resulting battery expansion rate increases (especially the thickness expansion rate increases, causing the battery to be too thick); at the same time, compared with the first arc segment 137, the second arc segment 135 of the edge wall 13 is close to the corner of the membrane shell 1, which is conducive to the battery core 2 and the corner of the membrane shell 1 having a relatively large gap space, which can inhibit the battery core 2 from squeezing and stretching the membrane shell 1 due to the expansion of the battery core 2 and other factors, and the resulting rupture (corner crack) of the corner of the membrane shell 1. Therefore, the present invention can provide battery safety and cycle life (cycle stability) and other performance, and avoid battery cycle failure and other problems.

[0043] As mentioned above, the membrane shell 1 includes a first main body and a second main body 14, at least one of which has a cavity 100, and a first side portion 11, an edge portion 12, and a prism 13 connected between the first side portion 11 and the edge portion 12 that surround the cavity 100. That is, the membrane shell 1 can be a single-pit membrane shell (i.e., one of the first main body and the second main body 14 has a cavity 100), or a double-pit membrane shell (i.e., the first main body and the second main body 14 each have a cavity 100). The structure of the membrane shell 1 is specifically described below by taking the first main body having a cavity 100 as an example. When the second main body has a cavity 100, its structure is similar to the structure of the first main body having a cavity 100 described below, and will not be described in detail.

[0044] The first main body portion includes a cavity 100, a first side portion 11 and an edge portion 12 which are connected to each other, the edge portion 12 is located on the peripheral side of the cavity 100, the first side portion 11 is located on one side of the edge portion 12 in the depth direction (third direction z) of the cavity 100, and the second main body portion 14 is located on the other side of the edge portion 12 in the depth direction of the cavity 100; after encapsulating the battery cell 2, the second main body portion 14 covers the cavity 100 and is connected to the edge portion 12, and can be specifically bonded to close the cavity 100.

[0045] Continue to refer Figure 4 and Figure 5 The membrane shell 1 includes an edge portion 12 located on at least one side of the membrane shell 1 in the first direction x, and an edge portion 12 located on at least one side of the membrane shell 1 in the second direction y, and an edge wall 13 is connected to each edge portion 12 and the first side portion 11 respectively.

[0046] Specifically, the membrane shell 1 (first main body) may include a plurality of side portions 12 and a plurality of prisms 13, and these side portions 12 are distributed along the circumference of the membrane shell 1 (also the circumference of the first main body), that is, these side portions 12 are connected in sequence and arranged around the circumference of the cavity 100. Among them, each two adjacent side portions 12 are connected to each other, and the planes where each two adjacent side portions 12 are located intersect (that is, the plane where one side portion 12 is located intersects with the plane where the other side portion 12 is located), and specifically, they may be substantially perpendicular to each other; each side portion 12 is connected to the first side portion 11 through a prism 13. Among them, each two adjacent side portions 12, and the prism 13 connected to the two side portions 12, intersect with the first side portion 11 (specifically, intersect with a top corner of the first side portion 11) to form an angular portion of the first main body of the membrane shell 1.

[0047] Continue to refer Figure 4 and Figure 5 The ribs 13 in the above-mentioned membrane shell 1 (first main body) are distributed along the circumference of the membrane shell 1, and every two adjacent ribs 13 are connected to each other, and the two adjacent ribs 13 are specifically connected to each other through their second arc segments 135 (that is, the second arc segment 135 at one end of one rib wall 13 is connected to the second arc segment 135 at one end of the other rib wall 13); the length directions of every two adjacent ribs 13 intersect, and specifically can be basically perpendicular to each other.

[0048] Generally, every two adjacent edge walls 13 are connected by an arc portion (the arc portion is located at the corner portion of the membrane shell 1), that is, the two adjacent edge walls 13 are transitioned by an arc, and the outer side surface of the arc portion (the side surface facing away from the cavity 100) is a convex arc surface, and correspondingly, the inner side surface of the arc portion (the side surface facing the cavity 100) is a concave arc surface.

[0049] In the embodiment of the present invention, two adjacent side portions 12 refer to two adjacent side portions 12 along the circumferential direction of the membrane shell 1 , and two adjacent edge walls 13 refer to two adjacent edge walls 13 along the circumferential direction of the membrane shell 1 .

[0050] Continue to refer Figure 4 and Figure 5 , there is a prism 13 on at least one side of the membrane shell 1 (first main body) in the first direction x, and specifically, there may be prism walls 13 on both sides of the membrane shell 1 in the first direction x; and / or, there is a prism wall 13 on at least one side of the membrane shell 1 (first main body) in the second direction y, and specifically, there may be prism walls 13 on both sides of the membrane shell 1 in the second direction y.

[0051] In the embodiment of the present invention, the first direction x and the second direction y intersect and may be perpendicular to each other. For example, the first direction x is the length direction of the membrane shell 1, and the second direction y is the width direction of the membrane shell 1 (eg Figure 4 and Figure 5 As shown); or, the first direction x is the width direction of the membrane shell 1, and the second direction y is the length direction of the membrane shell 1.

[0052] Specifically, the length direction of the membrane shell 1, the length direction of the first main body, and the length direction of the first side portion 11 are parallel to each other; the width direction of the membrane shell 1, the width direction of the first main body, and the width direction of the first side portion 11 are parallel to each other.

[0053] In addition, the first direction x intersects with the third direction z, and may be perpendicular to each other; the second direction y intersects with the third direction z, and may be perpendicular to each other. The depth direction of the cavity 100, the thickness direction of the membrane shell 1, and the third direction z are substantially parallel to each other.

[0054] In some specific embodiments, Figure 4 and Figure 5 As shown, there is a ridge wall 13 on at least one side of the membrane shell 1 (first main body) in the length direction, and specifically, there may be ridge walls 13 on both sides of the length direction of the membrane shell 1; there is a ridge wall 13 on at least one side of the membrane shell 1 (first main body) in the width direction, and specifically, there may be ridge walls 13 on both sides of the width direction of the membrane shell 1.

[0055] In general, if Figure 4 and Figure 5As shown, the membrane shell 1 (first main body) may include four side portions 12 (the number of the side portions 12 is four), and the four side portions 12 are respectively a first side portion 121, a second side portion 122, a third side portion 123 and a fourth side portion 124 which are sequentially distributed and sequentially connected along the circumference of the membrane shell 1, the first side portion 121 and the third side portion 123 are respectively located on the opposite sides of the first direction x of the membrane shell 1, and the second side portion 122 and the fourth side portion 124 are respectively located on the opposite sides of the second direction y of the membrane shell 1.

[0056] Accordingly, if Figure 4 and Figure 5 As shown, the membrane shell 1 includes four edge walls 13, which are respectively a first edge wall 131, a second edge wall 132, a third edge wall 133 and a fourth edge wall 134 which are distributed and connected in sequence along the circumference of the membrane shell 1, the first edge portion 121 and the first side portion 11 are connected via the first edge wall 131, the second edge portion 122 and the first side portion 11 are connected via the second edge wall 132, the third edge portion 123 and the first side portion 11 are connected via the third edge wall 133, and the fourth edge portion 124 and the first side portion 11 are connected via the fourth edge wall 134.

[0057] Accordingly, if Figure 4 and Figure 5 As shown, the membrane shell 1 includes four corner portions, namely: a first corner portion 101 formed by the intersection of the first side portion 11, the first edge portion 121, the first prism wall 131, the second edge portion 122, and the second prism wall 132; a second corner portion 102 formed by the intersection of the first side portion 11, the second edge portion 122, the second prism wall 132, the third edge portion 123, and the third prism wall 133; a third corner portion 103 formed by the intersection of the first side portion 11, the third edge portion 123, the third prism wall 133, the fourth edge portion 124, and the fourth prism wall 134; and a fourth corner portion 104 formed by the intersection of the first side portion 11, the fourth edge portion 124, the fourth prism wall 134, the first edge portion 121, and the first prism wall 131.

[0058] Continue to refer Figure 4 and Figure 5 The first side 121 and the first prism 131 connected between the first side portion 11 and the first side 121 are located on one side of the membrane shell 1 in the first direction x, the third side 123 and the third prism 133 connected between the first side portion 11 and the third side 123 are located on the other side of the membrane shell 1 in the first direction x, the length direction of the first prism 131 intersects with the first direction x, and specifically can be basically perpendicular to each other; the length direction of the third prism 133 intersects with the first direction x, and specifically can be basically perpendicular to each other.

[0059] Continue to refer Figure 4 and Figure 5The second side 122 and the second edge wall 132 connected between the first side 11 and the second side 122 are located on one side of the membrane shell 1 in the second direction y, the fourth side 124 and the fourth edge wall 134 connected between the first side 11 and the fourth side 124 are located on the other side of the membrane shell 1 in the second direction y, the length direction of the second edge wall 132 intersects with the second direction y, and specifically can be basically perpendicular to each other; the length direction of the fourth edge wall 134 intersects with the second direction y, and specifically can be basically perpendicular to each other.

[0060] In the embodiment of the present invention, among these prisms 13 in the above-mentioned membrane shell 1 (first main body), at least one prism 13 is designed with different arcs (that is, the prism 13 includes a first arc segment 137, a second arc segment 135 located at opposite ends of the first arc segment 137, and a transition arc segment 136 located between the second arc segment 135 and the first arc segment 137). Each prism 13 in the membrane shell 1 may be designed with a different arc, or some of the prisms 13 in the membrane shell 1 may be designed with different arcs (that is, not all of the prisms 13 in the membrane shell 1 are designed with different arcs).

[0061] In some embodiments, each of the prism walls 13 in the membrane shell 1 (first main body) includes a first arc segment 137, second arc segments 135 located at opposite ends of the first arc segment 137, and a transition arc segment 136 located between the second arc segment 135 and the first arc segment 137. Figure 4 and Figure 5 In the membrane shell 1 shown, each of the first prism 131, the second prism 132, the third prism 133 and the fourth prism 134 includes a first arc segment 137, a second arc segment 135 located at opposite ends of the first arc segment 137, and a transition arc segment 136 located between the second arc segment 135 and the first arc segment 137. At this time, the four edges (prisms 13) of the membrane shell 1 are all designed with different arcs, which is conducive to the balanced distribution of the gap space between the membrane shell 1 and the battery cell 2. Specifically, the reserved space near the four corners of the membrane shell 1 (four corners) is relatively large, that is, the gap space between the four corners of the membrane shell 1 (four corners) and the battery cell 2 is relatively large. The space between the edges of the membrane shell 1 and the battery cell 2 is relatively large, and the four corners of the membrane shell 1 are not easily compressed due to the expansion of the battery cell 2, thereby causing problems such as corner cracks. At the same time, the gap space between the middle area of ​​the edge wall 13 and the battery cell 2 is relatively small, which is conducive to the battery cell 2 and the middle area of ​​the four sides of the membrane shell 1 having a good fit. During the battery cycle, this area is not easy to be dented due to factors such as atmospheric pressure, and the edges are not easily warped, which leads to battery thickness expansion, battery failure and other problems. Therefore, the problems of corner cracks and edge protrusions of the battery membrane shell 1 can be improved, thereby improving the safety of the battery, inhibiting the thickness expansion during the battery cycle, and improving the battery's cycle life and other performance.

[0062] Continue to refer Figures 1 to 5 For any prism 13, there is a transition arc segment 136 between each second arc segment 135 and the first arc segment 137, that is, the second arc segment 135 located at one end of the first arc segment 137 is connected to the first arc segment 137 through a transition arc segment 136, and the second arc segment 135 located at the other end of the first arc segment 137 is connected to the first arc segment 137 through another transition arc segment 136. That is, the prism 13 includes the second arc segment 135, the transition arc segment 136, the first arc segment 137, the transition arc segment 136 and the second arc segment 135 distributed in sequence along the length direction of the prism 13, and the length L of the prism 13 is 13 is substantially equal to the length L of the second arc segment 135 located at one end of the first arc segment 137 135 , the length L of the transition arc segment 136 at one end of the first arc segment 137 136 , the length L of the first arc segment 137 137 , the length L of the transition arc segment 136 at the other end of the first arc segment 137 136 , the length L of the second arc segment 135 located at the other end of the first arc segment 137 135 sum.

[0063] For any prism 13, the length L of the transition arc segments 136 at the two opposite ends of the first arc segment 137 is 136 The length L of the second arc segment 135 at the opposite ends of the first arc segment 137 may be the same or different. 135 Can be the same or different.

[0064] In the embodiment of the present invention, unless otherwise specified, for any edge wall 13 with different arc designs, the length of any arc segment (such as the length L of the second arc segment 135) 135 , the length L of the transition arc 136 136 , the length L of the first arc segment 137 137 ) refer to the length of the arc segment in the length direction of the edge wall 13 where the arc segment is located.

[0065] Generally, for any edge wall 13, its length L 13 Slightly less than or substantially equal to the length of the membrane shell 1 in the length direction of the prism 13, the length L of the prism 13 13 The ratio of the length of the membrane shell 1 in the length direction of the rib wall 13 is, for example, about 90% to 97%. For example, the length of the membrane shell 1 in the length direction of any rib wall 13 may be substantially equal to the length L of the rib wall 13. 13 , the sum of the length of the arc portion connected to one end of the rib wall 13 in the longitudinal direction of the rib wall 13 and the length of the arc portion connected to the other end of the rib wall 13 in the longitudinal direction of the rib wall 13.

[0066] In some embodiments, for any prism 13, the length L of the second arc segment 135 thereof is 135 The length L of the prism 13 13 The ratio (L 135 / L 13 ) can be 10% to 32%, such as 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 32% or any two thereof, such as 15.8% to 26.4%. 135 / L 13 If L is too small, the proportion of the second arc segment 135 is too small, and the improvement effect on the corner crack problem of the membrane shell 1 is limited. 135 / L 13 If L is too large, the proportion of the second arc segment 135 will be too large, which will also affect the improvement effect of the edge protrusion of the membrane shell 1 to a certain extent. Therefore, by controlling L 135 / L 13 Within the above range, the proportion of the second arc segment 135 is within an appropriate range, which is beneficial to further improve the corner crack problem and edge protrusion problem of the battery membrane shell 1 and improve the safety and cycle life of the battery.

[0067] In some embodiments, for any prism 13, the length L of the transition arc segment 136 is 136 The length L of the prism 13 13 The ratio (L 136 / L 13 ) can be 5% to 27%, such as 5%, 8%, 10%, 13%, 15%, 18%, 20%, 22%, 25%, 27% or any two thereof, such as 8.4% to 23.2%. 136 / L 13 If L is too small, the transition arc segment 136 will account for a small proportion, which may easily lead to wrinkles on the appearance of the membrane shell 1, and affect the width and thickness of the battery to a certain extent, thereby affecting the energy density of the battery. 136 / L 13 If L is too large, the transition arc segment 136 will account for a large proportion, which will also affect the improvement effect of the corner cracks and edge protrusions of the membrane shell 1 to a certain extent. Therefore, by controlling L 136 / L 13 Within the above range, the battery can have a better appearance and avoid wrinkles, while further improving the corner cracks and edge protrusions of the battery membrane shell 1, thereby improving the safety and cycle life of the battery.

[0068] In some embodiments, for any prism 13, the length L of the first arc segment 137 thereof is 137The length L of the prism 13 13 The ratio (L 137 / L 13 ) can be 30% to 74%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 74% or any two thereof, such as 31.5% to 63.2%. 137 / L 13 If L is too small, the first arc segment 137 accounts for too small a proportion, and the improvement effect on the edge protrusion of the membrane shell 1 is limited. 137 / L 13 If L is too large, the first arc segment 137 will account for too large a proportion, which will also affect the improvement effect of the corner crack problem of the membrane shell 1 to a certain extent, and will also increase the battery wrinkle area to a certain extent, which is not conducive to the appearance of the battery. Therefore, by controlling L 137 / L 13 Within the above range, the proportion of the first arc segment 137 is within an appropriate range, which is beneficial to reducing the wrinkle area of ​​the battery membrane shell 1, making the battery have a better appearance, and at the same time further improving the corner crack problem and edge protrusion problem of the battery membrane shell 1, thereby improving the safety and cycle life of the battery.

[0069] Specifically, for any prism 13, the arc radius R of the first arc segment 137 is 137 The arc radius R of the second arc segment 135 135 The ratio (R 137 / R 135 ) can satisfy 1<R 137 / R 135 ≤8, R 137 / R 135 For example, it is 1.5, 2, 3, 4, 5, 6, 7, 8 or any two thereof, preferably 1<R 137 / R 135 ≤5, which is conducive to further improving the corner crack problem and edge protrusion problem of the battery membrane shell 1, and improving the safety and cycle life of the battery.

[0070] In some embodiments, the ridge wall 13 existing in the length direction of the membrane shell 1 may satisfy: 1<R 137 / R 135 ≤8, for example, 1<R 137 / R 135 ≤5, that is, for the edge wall 13 existing on either side of the length direction of the membrane shell 1, the arc radius R of the first arc segment 137 137 The arc radius R of the second arc segment 135 135 The ratio (R 137 / R 135 ) satisfies 1<R 137 / R 135 ≤8, for example, 1<R 137 / R 135 ≤5.

[0071] In some embodiments, the ridge wall 13 existing in the length direction of the membrane shell 1 satisfies: R 135 is 0.2 to 1.5 mm (i.e., for the edge wall 13 on either side of the length direction of the membrane shell 1, the arc radius R of the second arc segment 135 is 135 The thickness of the nanostructured carbon foam is 0.2 to 1.5 mm), for example, 0.2 mm, 0.4 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm or a range consisting of any two of them, for example, 0.4 to 1 mm.

[0072] In some embodiments, the edge wall 13 on either side of the length direction of the membrane shell 1 satisfies: R 137 is 0.8 to 5 mm (i.e., for the edge wall 13 on either side of the length direction of the membrane shell 1, the arc radius R of the first arc segment 137 is 137 The diameter of the optical fiber can be 0.8 to 5 mm), for example, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm or a range consisting of any two of them, for example, 1.2 to 3 mm.

[0073] In some embodiments, the edge wall 13 existing on either side of the width direction of the membrane shell 1 satisfies: 1<R 137 / R 135 ≤3, that is, for the edge wall 13 existing on either side in the width direction of the membrane shell 1, the arc radius R of the first arc segment 137 137 The arc radius R of the second arc segment 135 135 The ratio (R 137 / R 135 ) satisfies 1<R 137 / R 135 ≤5, further can be 1<R 137 / R 135 ≤3.

[0074] In some embodiments, the edge wall 13 on either side of the membrane shell 1 in the width direction satisfies: R 135 H / 2-A~H / 2+A (i.e., for the edge wall 13 existing on either side in the width direction of the membrane shell 1, the arc radius R of the second arc segment 135 135 Satisfy H / 2-A≤R 135 ≤H / 2+A), and can further be H / 2-A~H / 2, wherein A is 0.5~2H / 5, H is the depth of the cavity 100, and R 135The units of A and H are both in mm.

[0075] In some embodiments, the edge wall 13 on either side of the membrane shell 1 in the width direction satisfies: R 137 =H / 2-A~H / 2+B (i.e., for the edge wall 13 on either side of the membrane shell 1 in the width direction, the arc radius R of the first arc segment 137 is 137 Satisfy H / 2-A≤R 137 ≤H / 2+B), preferably H / 2 to H / 2+B, wherein A is 0.5 to 2H / 5, B is 0.5 to 2H / 5, H is the depth of the cavity 100, R 137 The units of A and H are both in mm.

[0076] In the embodiment of the present invention, the depth H of the cavity 100 is substantially equal to or slightly greater than the thickness T of the battery cell 2 placed in the cavity 100 , and H / T is, for example, 1 to 1.06.

[0077] For example, Figure 4 and Figure 5 As shown, the edge walls 13 on either side of the length direction of the membrane shell 1 are, for example, the first edge wall 131 and the third edge wall 133 , and the edge walls 13 on either side of the width direction of the membrane shell 1 are, for example, the second edge wall 132 and the fourth edge wall 134 .

[0078] In the embodiment of the present invention, for any edge wall 13, the arc radius R of the transition arc segment 136 is 136 The arc radius R between the second arc segment 135 135 and the arc radius R of the first arc segment 137 137 and increases along the direction from the second arc segment 135 to the first arc segment 137. The arc radius R of the transition arc segment 136 at one end close to the second arc segment 135 is 136 The arc radius R is substantially equal to the second arc segment 135 135 The arc radius of the transition arc segment 136 close to the first arc segment 137 is substantially equal to the arc radius R of the first arc segment 137. 137 , the arc radius R of the transition arc segment 136 136 Specifically, it can gradually increase (i.e., gradually increase) from the second arc segment 135 to the first arc segment 137, so that the intersection of the second arc segment 135 and the first arc segment 137 gradually transitions, which is conducive to balancing the second arc segment and the first arc segment, so that the membrane shell has a better appearance and is not easy to wrinkle.

[0079] In the embodiment of the present invention, for any prism 13, its cross section perpendicular to its length direction is a curved surface, its outer side surface (the side surface facing away from the cavity 100) is a convex curved surface, and correspondingly, its inner side surface (the side surface facing the cavity 100) is a concave curved surface. Correspondingly, for any arc segment on the prism 13 (such as the second arc segment 135, the transition arc segment 136, and the first arc segment 137), the cross section of the arc segment perpendicular to the length direction of the prism 13 where it is located is a curved surface, the outer side surface of the arc segment (the side surface facing away from the cavity 100) is a convex curved surface, and correspondingly, the inner side surface of the arc segment (the side surface facing the cavity 100) is a concave curved surface.

[0080] Continue to refer Figure 1 , Figure 2 and Figure 3 For any rib wall 13, the rib wall 13 is substantially tangent to the first side portion 11 connected to one side of the rib wall 13, and substantially tangent to the edge portion 12 connected to the other side of the rib wall 13. Specifically, the outer side surface of the rib wall 13 (such as Figures 1 to 3 03 surface in the middle) and the outer side surface of the first side portion 11 connected to one side of the edge wall 13 (such as Figures 1 to 3 The 01 surface in the figure is substantially tangent to the outer side surface of the edge portion 12 connected to the other side of the edge wall 13 (such as Figures 1 to 3 02) is basically tangent. For example, in Figure 4 and Figure 5 In the membrane shell 1 shown, one side of the first prism 131 is basically tangent to the first side portion 11, and the other side is basically tangent to the first edge portion 121, one side of the second prism 132 is basically tangent to the first side portion 11, and the other side is basically tangent to the second edge portion 122, one side of the third prism 133 is basically tangent to the first side portion 11, and the other side is basically tangent to the third edge portion 123, and one side of the fourth prism 134 is basically tangent to the first side portion 11, and the other side is basically tangent to the fourth edge portion 124.

[0081] Accordingly, if Figures 1 to 3 As shown, for any arc segment on the prism 13 (such as the second arc segment 135, the transition arc segment 136, and the first arc segment 137), it is substantially tangent to the first side portion 11 connected to one side of the arc segment, and substantially tangent to the edge portion 12 connected to the other side of the arc segment. Specifically, the outer side surface of the arc segment (such as Figures 1 to 3 03 surface in the middle) and the outer side surface of the first side portion 11 connected to one side of the arc segment (such as Figures 1 to 3 The 01 surface in the circle is substantially tangent (forming a tangent line L1) and is connected to the outer side surface of the edge 12 on the other side of the arc segment (such as Figures 1 to 3 The 02 surface in the figure is basically tangent (forming the tangent line L2).

[0082] In the embodiment of the present invention, for any arc segment on the prism wall 13, the arc radius (such as R 135 , R 136 , R 137 ) may specifically refer to the radius of the arc curve A corresponding to the outer side surface of the arc segment in the orthographic projection of the arc segment. The orthographic projection of the arc segment refers to the projection of the arc segment on a plane perpendicular to the length direction of the prism 13 where the arc segment is located (i.e., the orthographic projection of the arc segment is perpendicular to the length direction of the prism 13 where the arc segment is located).

[0083] Specifically, if Figures 1 to 3 As shown, for any arc segment on the ridge wall 13, the outer side surface of the arc segment forms a corresponding arc curve A in the orthographic projection of the arc segment. The center O1 corresponding to the arc curve A is the intersection of the perpendicular line T1 of the tangent line L1 and the perpendicular line T2 of the tangent line L2. The arc radius r1 (such as R 135 , R 136 , R 137 ) is the distance from the center O1 to the tangent line L1 (or tangent line L2).

[0084] In the embodiment of the present invention, for any prism 13, the length L of the second arc segment 135 located at the two opposite ends of the first arc segment 137 is 135 The arc radius R of the second arc segment 135 located at the opposite ends of the first arc segment 137 may be the same or different. 135 The lengths L of the transition arc segments 136 at opposite ends of the first arc segment 137 may be the same or different. 136 Can be the same or different.

[0085] In the embodiment of the present invention, when the mold core 3 includes a plurality of rib walls 13, the length L of the first arc segment 137 of every two rib walls 13 is 137 The arc radius R of the first arc segment 137 of each two prism walls 13 may be the same or different. 137 The length L of the second arc segment 135 of each two prism walls 13 may be the same or different. 135 The arc radius R of the second arc segment 135 of each two prism walls 13 may be the same or different. 135 The length L of the transition arc 136 between each two prism walls 13 may be the same or different. 136 Can be the same or different.

[0086] In the embodiment of the present invention, the film shell 1 is a soft packaging film shell 1 (ie, the film shell 1 is punched out of a soft packaging film), which may specifically include an aluminum-plastic film shell 1 (ie, the film shell 1 is punched out of an aluminum-plastic film).

[0087] In some embodiments, the thickness of the flexible packaging film may be 70-200 μm, for example, 70 μm, 90 μm, 100 μm, 120 μm, 140 μm, 150 μm, 170 μm, 200 μm, or a range consisting of any two thereof.

[0088] The present invention also provides a battery. Figures 1 to 7 As shown, the battery comprises the membrane shell 1 and the battery cell 2 in the membrane shell 1. The battery has the advantages corresponding to the membrane shell 1, which will not be described in detail. For the introduction of the membrane shell 1, please refer to the above content, which will not be described in detail below.

[0089] Specifically, the battery cell 2 includes electrode sheets and separators, some of which are positive electrode sheets and other electrode sheets are negative electrode sheets. The separator is located between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet and the negative electrode sheet to avoid short circuit between the positive electrode sheet and the negative electrode sheet.

[0090] In some embodiments, the battery cell has a bending portion, and the bending portion of the battery cell is located on at least one side of the battery cell 2 in the second direction y, and specifically can be located on two opposite sides of the battery cell 2 in the second direction y. In the bending portion of the battery cell 2, the positive electrode sheet and the negative electrode sheet each have a corresponding bending section 202 (for example, a first straight section and a first bending section of the positive electrode sheet, and a second straight section and a second bending section of the negative electrode sheet).

[0091] In some specific embodiments, Figure 7 As shown, the battery cell 2 can be a wound battery cell 2 (wound core), that is, the positive electrode sheet and the negative electrode sheet each have a wound structure. The positive electrode sheet includes a plurality of first straight sections and a first bending section connected between each two adjacent first straight sections. The number of the first bending sections is at least one, and can be multiple. The positive electrode sheet is bent through the first bending section to form a wound structure; the negative electrode sheet includes a plurality of second straight sections and a second bending section connected between each two adjacent second straight sections. The number of the second bending sections is at least one, and can be multiple. The negative electrode sheet is bent through the second bending section to form a wound structure. The first straight section and the second straight section are stacked in the thickness direction of the battery cell 2.

[0092] In other embodiments, the battery cell 2 can be a stacked battery cell 2 (stacked core). Specifically, the battery cell 2 can include multiple positive electrode sheets and multiple negative electrode sheets, which are alternately stacked, and each positive electrode sheet is separated from the negative electrode sheet by a separator, and each negative electrode sheet is separated from the positive electrode sheet by a separator.

[0093] Specifically, at least one side of the battery cell 2 exposes the end surface 200 of the electrode sheet (the end surface is parallel to the thickness direction of the electrode sheet). Specifically, the battery cell 2 may expose the end surface 200 of the electrode sheet on two opposite sides in the first direction x and / or expose the end surface 200 of the electrode sheet on two opposite sides in the second direction y.

[0094] Exemplarily, when the battery cell 2 is a laminated battery cell 2 , the end surfaces 200 of the electrode sheets are exposed at two opposite sides in the first direction x and two opposite sides in the second direction y, respectively.

[0095] In addition, if Figure 7 As shown, when the battery cell 2 is a wound battery cell 2, the electrode sheets therein include a straight section 201 and a bent section 202 that are interconnected (for example, a first straight section and a first bent section of the positive electrode sheet, and a second straight section and a second bent section of the negative electrode sheet), and the bent sections 202 are located on opposite sides of the battery cell 2 in the second direction y, so that the opposite sides of the battery cell 2 in the second direction y are the bent sections 202 (the end faces 200 of the electrode sheets are not exposed), and the end faces 200 of the electrode sheets (the end faces of the positive electrode sheets and the end faces of the negative electrode sheets) are exposed on opposite sides of the battery cell 2 in the first direction x.

[0096] In some embodiments, the edge wall 13 (such as Figures 4 to 6 The first edge wall 131 and the third edge wall 133 in the embodiment may satisfy: 1<R 137 / R 135 ≤8, preferably 1<R 137 / R 135 ≤5.

[0097] In some embodiments, the edge wall 13 (such as Figures 4 to 6 The first prism 131 and the third prism 133 in the embodiment may satisfy: R 135 The diameter is 0.2 to 1.5 mm, for example, 0.2 mm, 0.4 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm or a range consisting of any two thereof, and preferably 0.4 to 1 mm.

[0098] In some embodiments, the edge wall 13 (such as Figures 4 to 6 The first prism 131 and the third prism 133 in the embodiment may satisfy: R 137 The diameter is 0.8 to 5 mm, for example, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm or a range consisting of any two thereof, and preferably 1.2 to 3 mm.

[0099] In some embodiments, the edge wall 13 of the membrane shell 1 located on the side of the battery core 2 having the bent section 202 (i.e., the edge wall 13 located on the side of the membrane shell 1 in the second direction y (e.g., Figures 4 to 6 The second edge wall 132 and the fourth edge wall 134 in the embodiment may satisfy: 1<R 137 / R 135 ≤5, further can be 1<R 137 / R 135 ≤3.

[0100] In some embodiments, the edge wall 13 (eg, Figures 4 to 6 The second prism 132 and the fourth prism 134 in the embodiment may satisfy: R 135 It is T / 2-A to T / 2+A, and can further be H / 2-A to H / 2, wherein A is 0.5 to 2T / 5, T is the thickness of the battery cell 2, and R 135 The units of and T are both in mm.

[0101] In some embodiments, the edge wall 13 (eg, Figures 4 to 6 The second prism 132 and the fourth prism 134 in the embodiment may satisfy: R 137 It is T / 2-A to T / 2+B, preferably T / 2 to T / 2+B, wherein A is 0.5 to 2T / 5, B is 0.5 to 2T / 5, T is the thickness of the battery 2, and R 137 The units of and T are both in mm.

[0102] In some embodiments, the thickness T of the battery cell 2 can be 1 to 200 mm, for example, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 30 mm, 50 mm, 70 mm, 100 mm, 130 mm, 150 mm, 180 mm, 200 mm or a range consisting of any two thereof.

[0103] Specifically, for any edge wall in the membrane shell, the arc radius R of the first arc segment is 137 Not exceeding the thickness T of the battery cell, generally R 137 <T.

[0104] In addition, if Figure 6 and Figure 7 As shown, the battery further includes a pole ear arranged on the battery cell 2, and the pole ear extends out of the membrane shell 1. The pole ear can be specifically arranged on a side of the end face 200 of the battery cell 2 where the electrode sheet is exposed, and extends out of the membrane shell 1 from a side of the end face 200 of the battery cell 2 where the electrode sheet is exposed.

[0105] Specifically, Figure 6 and Figure 7As shown, the tabs provided on the battery cell 2 include a positive tab 211 connected to the positive electrode sheet, and a negative tab 221 connected to the negative electrode sheet, and the positive tab 211 and the negative tab 221 are respectively extended out of the membrane shell 1. The positive tab 211 and the negative tab 221 can be provided on the same side of the battery cell 2, for example, the positive tab 211 and the negative tab 221 are both provided on one side of the battery cell 2 in the first direction x, and extend out of the membrane shell 1 from one side of the battery cell 2 in the first direction x.

[0106] As mentioned above, the membrane shell 1 includes a cavity 100, and the battery cell 2 is located in the cavity 100 of the membrane shell 1. The first main body of the membrane shell 1 includes a first side portion 11 and an edge portion 12 connected to each other, and the edge portion 12 is located on the peripheral side of the cavity 100. The first side portion 11 is located on one side of the edge portion 12 in the depth direction (third direction z) of the cavity 100, and the second main body portion 14 is located on the other side of the edge portion 12 in the depth direction of the cavity 100, and the second main body portion 14 covers the cavity 100 and is connected to the edge portion 12 to close the cavity 100.

[0107] Specifically, Figure 4 As shown, the first main body portion of the membrane shell 1 may include an extension portion 15 which is arranged on a side of the edge portion 12 facing the second main body portion 14 and extends outward in a direction away from the cavity 100. The second main body portion 14 is connected to the extension portion 15, for example, by bonding, to close the cavity 100 and simultaneously form a sealed edge of the membrane shell 1 (the sealed edge is formed by connecting the second main body portion 14 and the extension portion 15).

[0108] Generally, the edge seal of the membrane shell 1 includes a top edge seal and a side edge seal, and there are side edge seals on opposite sides of the top edge seal in the length direction. Figure 4 As shown, the top seal can be located on one side of the film shell 1 in the first direction x, and on the other side of the film shell 1 in the first direction x, the second main body 14 and the first main body are connected in an integrally formed manner (that is, the second main body 14 is formed by extending outward from the first main body, and before the flexible packaging film is punched into the film shell 1, the second main body 14 and the first main body together form a complete flexible packaging film), and the side seals are located on the opposite sides of the film shell 1 in the second direction y (that is, there are side seals on both opposite sides of the film shell 1 in the second direction y).

[0109] Specifically, Figure 4 , Figure 6 and Figure 7As shown, the above-mentioned tabs (positive tab 211, negative tab 221) extend out of the membrane shell 1 from the top seal, and at the top seal, the second main body 14 is located on one side of the tabs (positive tab 211, negative tab 221) in the third direction z, and the extension 15 of the first main body is located on the other side of the tabs (positive tab 211, negative tab 221) in the third direction z. At this time, in the membrane shell 1 of the battery, the first side 121 (the side 12 located on the side of the membrane shell 1 with the top seal) is the top side (the first edge wall 131 is the edge of the top side), the third side 123 is the bottom side (the third edge wall 133 is the edge of the bottom side), and the second side 122 and the fourth side 124 are side sides (the second edge wall 132 and the fourth edge wall 134 are the edges of the side side).

[0110] In the embodiment of the present invention, the edge wall 13 (such as Figures 4 to 6 In the first edge wall 131), the arc radius of the middle area is relatively large, which is beneficial to improve the consistency of the height of the entire battery cavity and the top sealing edge of the battery, so that the width of the top sealing edge can be further reduced, thereby improving the energy density (ED) of the battery.

[0111] Specifically, the thickness direction of the battery, the thickness direction of the membrane shell 1, and the thickness direction of the battery cell 2 (also the thickness direction of the electrode sheet in the stacked core or the thickness direction of the straight section 201 of the electrode sheet in the rolled core) are parallel to each other, the width direction of the battery, the width direction of the membrane shell 1, and the width direction of the battery cell 2 are parallel to each other, and the length direction of the battery, the length direction of the membrane shell 1, and the length direction of the battery cell 2 are parallel to each other.

[0112] Specifically, when the battery cell 2 is a winding core, the width direction of the electrode sheet (positive electrode sheet, negative electrode sheet) (also the width direction of the straight section 201) can be parallel to the length direction of the battery cell 2 (such as Figures 4 to 7 or, the width direction of the electrode sheet (positive electrode sheet, negative electrode sheet) (also the width direction of the straight section 201) is parallel to the width direction of the battery cell 2.

[0113] The battery of the embodiment of the present invention may be a lithium-ion battery, specifically a soft-pack lithium-ion battery.

[0114] Specifically, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer located on the surface of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, a conductive agent and a binder, and the positive electrode active material may include one or more of lithium cobalt oxide, lithium iron phosphate, nickel cobalt manganese lithium, nickel cobalt aluminum lithium, lithium manganese oxide and lithium-rich manganese-based lithium.

[0115] Specifically, the negative electrode sheet may include a negative electrode current collector, and a negative electrode active material layer located on the surface of the negative electrode current collector, the negative electrode active material layer includes a negative electrode active substance, a conductive agent and a binder, the negative electrode active substance may include one or more of graphite, mesophase carbon microbeads, lithium titanate, silicon negative electrode, silicon-carbon negative electrode and alloy negative electrode, wherein the graphite may include natural graphite and / or artificial graphite, and the graphite used may specifically be graphite powder.

[0116] In an embodiment of the present invention, the conductive agent and the binder in the negative electrode sheet and the positive electrode sheet may be conventional conductive materials and binder materials in the art. For example, the conductive agent may include at least one of conductive carbon black, Ketjen black, single-walled carbon nanotubes, and multi-walled carbon nanotubes. The binder in the positive electrode sheet may include a polyvinylidene fluoride (PVDF)-based adhesive, such as PVDF. The binder in the negative electrode sheet may include styrene-butadiene rubber (SBR) and / or carboxymethyl cellulose, etc.

[0117] In the embodiment of the present invention, the flexible packaging film can be punched into a film shell 1 using a mold core 3 through conventional processes in the field, and the film shell 1 and battery cells 2 and other components can be assembled into a battery through conventional processes in the field. For example, after the flexible packaging film is punched into a film shell 1 having a cavity 100, the battery cell 2 is placed in the cavity 100 of the film shell 1, and then the battery is obtained through processes such as packaging, baking, liquid injection, formation, sorting, secondary sealing, open circuit voltage testing (OCV) and packaging. The processes involved are all conventional operations in the field and are not particularly limited thereto.

[0118] In the embodiment of the present invention, the film shell material (such as a flexible packaging film) is punched into the above-mentioned film shell 1 through the mold core 3, such as Figures 8 to 10 As shown, the mold core 3 includes a main side surface 31, a side surface 32, and an edge surface 33 connected between the main side surface 31 and the side surface 32; the plane where the main side surface 31 is located intersects with the plane where the side surface 32 is located; the edge surface 33 includes a first arc surface 337, a second arc surface 335 located at opposite ends of the first arc surface 337, and a transition arc surface 336 connected between the first arc surface 337 and the second arc surface 335; the arc radius R of the first arc surface 337 337 Greater than the arc radius R of the second arc surface 335 335 ; The arc radius R of the transition arc surface 336 336 The arc radius R between the second arc surface 335 335 The arc radius R of the first arc surface 337 337 The mold core 3 has the same advantages as the membrane shell 1, which will not be described in detail.

[0119] Among them, the main side surface 31 of the mold core 3 corresponds to the first side portion 11 of the membrane shell 1, the side surface 32 corresponds to the side portion 12 of the membrane shell 1 (one side surface 32 corresponds to one side portion 12), the edge surface 33 corresponds to the edge wall 13 of the membrane shell 1 (one edge surface 33 corresponds to one edge wall 13), the first arc surface 337 of the edge surface 33 corresponds to the first arc segment 137 of the edge wall 13, the second arc surface 335 of the edge surface 33 corresponds to the second arc segment 135 of the edge wall 13 (one second arc surface 335 corresponds to one second arc segment 135), and the transition arc surface 336 of the edge surface 33 corresponds to the transition arc segment 136 of the membrane shell 1 (one transition arc surface 336 corresponds to one transition arc segment 136).

[0120] Specifically, in the process of using the above-mentioned mold core 3 to punch the flexible packaging film into the film shell 1, the main side surface 31 of the mold core 3 is placed in the area corresponding to the first side portion 11 on the flexible packaging film, and the flexible packaging film is punched into the film shell 1 with the cavity 100. The width of the mold core 3 is substantially equal to the width of the formed cavity 100, and the length of the mold core 3 is substantially equal to the length of the formed cavity 100. After the punching is completed, before the mold core 3 is taken out from the cavity 100 of the film shell 1, the main side surface 31 of the mold core 3 and the first side portion 11 of the film shell 1 are in contact with each other, and each side surface 32 of the mold core 3 and the side portion 12 of the film shell 1 corresponding to the side surface 32 are in contact with each other. Fitting, each edge face 33 of the mold core 3 is fitted with the edge wall 13 corresponding to the edge face 33 in the membrane shell 1 (correspondingly, each arc surface of the edge face 33 (such as the second arc surface 335, the transition arc surface 336, the first arc surface 337) and the arc segment corresponding to the arc surface in the edge wall 13 are fitted (the second arc surface 335 and the second arc segment 135 are fitted, the transition arc surface 336 and the transition arc segment 136 are fitted, and the first arc surface 337 and the first arc segment 137 are fitted)); after the mold core 3 is removed from the cavity 100 of the membrane shell 1, the battery cell 2 is placed in the cavity 100, and the battery cell 2 packaging and other processes are carried out to obtain a battery.

[0121] Generally, for any edge face 33 in the mold core 3, the length L of the edge face 33 is 33 It is substantially equal to the length L of the edge wall 13 corresponding to the edge face 33 in the membrane shell 1 punched by the mold core 3. 13 , the length L of the first arc surface 337 337 is substantially equal to the length L of the first arc segment 137 corresponding to the first arc surface 337 in the membrane shell 1 punched by the mold core 3. 137 , the arc radius R of the first arc surface 337 337 The radius R of the first arc segment 137 corresponding to the first arc surface 337 is substantially equal to 137 , the length L of the second arc surface 335 335The length L of the second arc segment 135 corresponding to the second arc surface 335 in the membrane shell 1 formed by punching the mold core 3 is substantially equal to 135 , the arc radius R of the second arc surface 335 335 The arc radius R is substantially equal to the arc radius R of the second arc segment 135 corresponding to the first arc surface 337. 135 , the length L of the transition arc surface 336 336 It is substantially equal to the length L of the transition arc segment 136 corresponding to the transition arc surface 336 in the membrane shell 1 formed by punching the mold core 3. 136 .

[0122] like Figure 8 As shown, the core 3 includes a recessed area 300 located on the same side of the core 3 in the thickness direction as the main side 31, the recessed area 300 does not penetrate the core 3 in the thickness direction of the core 3, the main side 31 is arranged on the circumferential side of the recessed area 300, and the edge surface 33 is located on the side of the main side 31 away from the recessed area 300.

[0123] Continue to refer Figure 8 The core 3 may include a plurality of side surfaces 32 and a plurality of edge surfaces 33, and these side surfaces 32 are distributed along the circumference of the core 3 and are connected in sequence. Among them, each two adjacent side surfaces 32 are connected to each other, and the planes where each two adjacent side surfaces 32 are located intersect (that is, the plane where one side surface 32 is located intersects with the plane where the other side surface 32 is located), and specifically, they may be substantially perpendicular to each other; an edge surface 33 is respectively connected between each side surface 32 and the main side surface 31 (that is, each side surface 32 is connected to the main side surface 31 through an edge surface 33). Among them, each two adjacent side surfaces 32, the two edge surfaces 33 connected to the two side surfaces 32, and the main side surface 31 intersect to form a top corner of the core 3, and the top corner of the core 3 corresponds to the corner portion of the membrane shell 1 (one top corner portion corresponds to one corner portion).

[0124] Continue to refer Figure 8 The facets 33 in the above-mentioned core 3 are distributed along the circumference of the core 3, and every two adjacent facets 33 are connected to each other, and the two adjacent facets 33 are specifically connected to each other through their second curved surfaces 335 (that is, the second curved surface 335 at one end of one facet 33 is connected to the second curved surface 335 at one end of another facet 33); the length directions of every two adjacent facets 33 intersect, and specifically can be basically perpendicular to each other.

[0125] In general, if Figure 8 As shown, every two adjacent edge faces 33 are connected by an arc surface, which is a convex arc surface, and the arc surface corresponds to the arc portion of the formed membrane shell 1 (one arc surface corresponds to one arc portion).

[0126] In the embodiment of the present invention, two adjacent side surfaces 32 refer to two adjacent side surfaces 32 along the circumferential direction of the mold core 3 , and two adjacent edge surfaces 33 refer to two adjacent edge surfaces 33 along the circumferential direction of the mold core 3 .

[0127] Continue to refer Figure 8 There is a facet 33 on at least one side of the mold core 3 in the first direction x, specifically, there may be facets 33 on both sides of the mold core 3 in the first direction x; there is a facet 33 on at least one side of the mold core 3 in the second direction y, specifically, there may be facets 33 on both sides of the mold core 3 in the second direction y.

[0128] Specifically, the first direction x can be the length direction of the mold core 3, and the second direction y can be the width direction of the mold core 3 (eg Figure 8 or, the first direction x is the width direction of the mold core 3, and the second direction y is the length direction of the mold core 3. The thickness direction of the mold core 3 is parallel to the third direction z.

[0129] In some specific embodiments, Figure 8 As shown, there is an edge face 33 on at least one side in the length direction of the core 3, and specifically, there may be an edge face 33 on both sides of the length direction of the core 3; there is an edge face 33 on at least one side in the width direction of the core 3, and specifically, there may be an edge face 33 on both sides of the width direction of the core 3.

[0130] In general, if Figure 8 As shown, the core 3 may include four side surfaces 32 (the number of the side surfaces 32 is four), and the four side surfaces 32 are respectively a first side surface 321, a second side surface 322, a third side surface and a fourth side surface which are distributed and connected in sequence along the circumference of the core 3, the first side surface 321 and the third side surface are respectively located on the opposite sides of the core 3 in the first direction x, and the second side surface 322 and the fourth side surface are respectively located on the opposite sides of the core 3 in the second direction y.

[0131] Accordingly, if Figure 8 As shown, the core 3 includes four edge faces 33, which are respectively a first edge face 331, a second edge face 332, a third edge face 333 and a fourth edge face 334 which are distributed and connected in sequence along the circumference of the core 3. The first side surface 321 and the main side surface 31 are connected via the first edge face 331, the second side surface 322 and the main side surface 31 are connected via the second edge face 332, the third side surface and the main side surface 31 are connected via the third edge face 333, and the fourth side surface and the main side surface 31 are connected via the fourth edge face 334.

[0132] Accordingly, if Figure 8As shown, the mold core 3 includes four vertex corners, which are: a first vertex corner 301 formed by the intersection of the main side surface 31, the first side surface 321, the first edge surface 331, the second side surface 322, and the second edge surface 332; a second vertex corner 302 formed by the intersection of the main side surface 31, the second side surface 322, the second edge surface 332, the third side surface, and the third edge surface 333; a third vertex corner 303 formed by the intersection of the main side surface 31, the third side surface, the third edge surface 333, the fourth side surface, and the fourth edge surface 334; and a fourth vertex corner 304 formed by the intersection of the main side surface 31, the fourth side surface, the fourth edge surface 334, the first side surface 321, and the first edge surface 331.

[0133] Continue to refer Figure 8 The first side surface 321 and the first edge surface 331 connected between the main side surface 31 and the first side surface 321 are located on one side of the core 3 in the first direction x, the third side surface and the third edge surface 333 connected between the main side surface 31 and the third side surface are located on the other side of the core 3 in the first direction x, the length direction of the first edge surface 331 intersects with the first direction x, and specifically can be basically perpendicular to each other; the length direction of the third edge surface 333 intersects with the first direction x, and specifically can be basically perpendicular to each other.

[0134] Continue to refer Figure 8 The second side surface 322 and the second edge surface 332 connected between the main side surface 31 and the second side surface 322 are located on one side of the mold core 3 in the second direction y, the fourth side surface and the fourth edge surface 334 connected between the main side surface 31 and the fourth side surface are located on the other side of the mold core 3 in the second direction y, the length direction of the second edge surface 332 intersects with the second direction y, and specifically can be basically perpendicular to each other; the length direction of the fourth edge surface 334 intersects with the second direction y, and specifically can be basically perpendicular to each other.

[0135] Each of the facets 33 in the mold core 3 includes a first arc surface 337, second arc surfaces 335 located at opposite ends of the first arc surface 337, and a transition arc surface 336 located between the second arc surface 335 and the first arc surface 337. Figure 8 In the mold core 3 shown, each of the first edge surface 331, the second edge surface 332, the third edge surface 333 and the fourth edge surface 334 respectively includes a first arc surface 337, a second arc surface 335 located at opposite ends of the first arc surface 337, and a transition arc surface 336 located between the second arc surface 335 and the first arc surface 337. At this time, the four edges (edge ​​surfaces 33) of the mold core 3 are all designed with different arcs, so that the four edges (edge ​​walls 13) of the formed membrane shell 1 are all designed with different arcs.

[0136] Continue to refer Figure 8For any edge face 33, there is a transitional arc surface 336 between each second arc surface 335 and the first arc surface 337, that is, the second arc surface 335 located at one end of the first arc surface 337 is connected to the first arc surface 337 through a transitional arc surface 336, and the second arc surface 335 located at the other end of the first arc surface 337 is connected to the first arc surface 337 through another transitional arc surface 336. That is, the edge face 33 includes the second arc surface 335, the transitional arc surface 336, the first arc surface 337, the transitional arc surface 336 and the second arc surface 335 distributed in sequence along the length direction of the edge face 33, and the length L of the edge face 33 is 33 The length L of the second arc surface 335 is substantially equal to the length L of the second arc surface 335 located at one end of the first arc surface 337 335 , the length L of the transition arc surface 336 at one end of the first arc surface 337 336 , the length L of the first arc surface 337 337 , the length L of the transition arc surface 336 at the other end of the first arc surface 337 336 , the length L of the second arc surface 335 located at the other end of the first arc surface 337 335 sum.

[0137] In the embodiment of the present invention, unless otherwise specified, for any edge face 33, the length of any arc surface thereof (such as the length L of the second arc surface 335) 335 , the length L of the transition arc surface 336 336 , the length L of the first arc surface 337 337 ) refer to the length of the arc surface in the length direction of the edge surface 33 where the arc surface is located.

[0138] Generally, for any edge face 33, its length L 33 Slightly less than or substantially equal to the length L of the mold core 3 in the length direction of the edge face 33 30 , the length L of the edge face 33 33 The length L of the core 3 in the length direction of the edge surface 33 30 For example, the length L of the core 3 in the longitudinal direction of any edge face 33 is about 93% to 97% (such as 95%). 30 It can be substantially equal to the length L of the face 33 33 , the sum of the length of the arc surface connected to one end of the edge surface 33 in the length direction of the edge surface 33 and the length of the arc surface connected to the other end of the edge surface 33 in the length direction of the edge surface 33.

[0139] In some embodiments, for any edge face 33, the length L of the second curved surface 335 is 335 The length L of the core 3 in the length direction of the edge surface 33 30 The ratio (L 335 / L 30) can be 10% to 30%, for example, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% or any two thereof, preferably 15% to 25%.

[0140] In some embodiments, for any edge face 33, the length L of the transition arc surface 336 is 336 The length L of the core 3 in the length direction of the edge surface 33 30 The ratio (L 336 / L 30 ) can be 5% to 25%, for example, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 22%, 25% or a range consisting of any two of them, preferably 8% to 22%.

[0141] In some embodiments, for any edge face 33, the length L of the first arc surface 337 is 337 The length L of the core 3 in the length direction of the edge surface 33 30 The ratio (L 337 / L 30 ) can be 30% to 70%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or a range consisting of any two of them, preferably 30% to 60%.

[0142] In some embodiments, for any edge face 33, the length L of the second curved surface 335 is 335 The length L of the edge face 33 33 The ratio (L 335 / L 33 ) can be 10% to 32%, for example, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 32% or a range consisting of any two of them.

[0143] In some embodiments, for any edge face 33, the length L of the transition arc surface 336 is 336 The length L of the edge face 33 33 The ratio (L 336 / L 33 ) can be in the range of 5% to 27%, for example, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 22%, 25% / 27% or any two thereof.

[0144] In some embodiments, for any edge face 33, the length L of the first arc surface 337 is 337 The length L of the edge face 33 33 The ratio (L 337 / L 33) can be 30% to 74%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 74% or a range consisting of any two of them.

[0145] Specifically, for any edge face 33, the arc radius R of the first arc surface 337 is 337 The arc radius R of the second arc surface 335 335 The ratio (R 337 / R 335 ) can satisfy 1<R 337 / R 335 ≤8, R 137 / R 135 For example, it is 1.5, 2, 3, 4, 5, 6, 7, 8 or any two thereof, preferably 1<R 137 / R 135 ≤5, which is beneficial to improving the corner crack problem and edge protrusion problem of the battery membrane shell 1, and improving the safety and cycle life of the battery.

[0146] In some embodiments, the edge faces 33 on either side of the length direction of the mold core 3 may satisfy: 1<R 337 / R 335 ≤8, preferably 1<R 337 / R 335 ≤5, that is, for any edge face 33 existing in the length direction of the core 3, the arc radius R of the first arc surface 337 337 The arc radius R of the second arc surface 335 335 The ratio (R 337 / R 335 ) satisfies 1<R 337 / R 335 ≤8, preferably 1<R 337 / R 335 ≤5.

[0147] In some embodiments, the edge faces 33 on either side of the length direction of the mold core 3 satisfy: R 335 is 0.2 to 1.5 mm (i.e., for the edge face 33 on either side of the length direction of the mold core 3, the arc radius R of the second arc face 335 is 335 The diameter of the nanostructured carbon foam is preferably 0.2 to 1.5 mm), for example, 0.2 mm, 0.4 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm or a range consisting of any two thereof, preferably 0.4 to 1 mm.

[0148] In some embodiments, the edge faces 33 existing in the length direction of the mold core 3 satisfy: R 3370.8 to 5 mm (i.e., for the edge face 33 on either side of the length direction of the mold core 3, the arc radius R of the first arc face 337 is 337 The diameter of the optical disc is preferably 0.8 to 5 mm), for example, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm or a range consisting of any two thereof, preferably 1.2 to 3 mm.

[0149] In some embodiments, the edge faces 33 existing on either side of the width direction of the mold core 3 satisfy: 1<R 337 / R 335 ≤3, that is, for the edge face 33 existing on any side in the width direction of the mold core 3, the arc radius R of the first arc surface 337 337 The arc radius R of the second arc surface 335 335 The ratio (R 337 / R 335 ) satisfies 1<R 137 / R 135 ≤5, further can be 1<R 337 / R 335 ≤3.

[0150] In some embodiments, the edge faces 33 existing on either side of the width direction of the mold core 3 satisfy: R 335 H / 2-A~H / 2+A (i.e., for the edge face 33 existing on any side in the width direction of the mold core 3, the arc radius R of the second arc face 335 335 Satisfy H / 2-A≤R 335 ≤H / 2+A), and can further be H / 2-A~H / 2, wherein A is 0.5~2H / 5, H is the depth of the cavity 100 of the membrane shell 1 punched by the mold core 3, and R 335 The units of A and H are both in mm.

[0151] In some embodiments, the edge faces 33 existing on either side of the width direction of the mold core 3 satisfy: R 337 =H / 2-A~H / 2+B (i.e., for the edge face 33 existing on any side in the width direction of the mold core 3, the arc radius R of the first arc face 337 is 337 Satisfy H / 2-A≤R 337 ≤H / 2+B), preferably H / 2 to H / 2+B, wherein A is 0.5 to 2H / 5, B is 0.5 to 2H / 5, R 337 The units of A and H are both in mm.

[0152] For example, Figure 8As shown, the edge faces 33 existing on either side of the length direction of the core 3 are, for example, the first edge face 331 and the third edge face 333 , and the edge faces 33 existing on either side of the width direction of the core 3 are, for example, the second edge face 332 and the fourth edge face 334 .

[0153] In the embodiment of the present invention, for any edge face 33, the arc radius R of the transition arc face 336 is 336 The arc radius R3 of the second arc surface 335 135 and the arc radius R of the first arc surface 337 337 The arc radius R of one end of the transition arc surface 336 close to the second arc surface 335 is 336 The arc radius R is substantially equal to the arc radius R of the second arc surface 335 335 The arc radius of the transition arc surface 336 close to the first arc surface 337 is substantially equal to the arc radius R of the first arc surface 337. 337 , the arc radius R of the transition arc surface 336 336 Specifically, the arc may gradually increase (ie, gradually increase) along the direction from the second arc surface 335 to the first arc surface 337 , so that the intersection of the second arc surface 335 and the first arc surface 337 is gradually transitioned.

[0154] In the embodiment of the present invention, Figures 8 to 10 As shown, for any edge face 33, any arc surface on the edge face 33 (such as the second arc surface 335, the transition arc surface 336, and the first arc surface 337) are all convex arc surfaces.

[0155] Continue to refer Figures 8 to 10 For any edge face 33, the edge face 33 is substantially tangent to the main side face 31 connected to one side of the edge face 33, and substantially tangent to the side face 32 connected to the other side of the edge face 33. Specifically, the edge face 33 (such as Fig. 9 and Fig.10 033 face in the figure) and the main side surface 31 connected to one side of the edge face 33 (such as Fig. 9 and Fig.10 013 surface in the figure) is substantially tangent to the side surface 32 (such as Fig. 9 and Fig.10 023 surface in the figure) is basically tangent. For example, in Figure 8 In the mold core 3 shown, one side of the first edge surface 331 is basically tangent to the main side surface 31, and the other side is basically tangent to the first side surface 321, one side of the second edge surface 332 is basically tangent to the main side surface 31, and the other side is basically tangent to the second side surface 322, one side of the third edge surface 333 is basically tangent to the main side surface 31, and the other side is basically tangent to the third side surface, and one side of the fourth edge surface 334 is basically tangent to the main side surface 31, and the other side is basically tangent to the fourth side surface.

[0156] Accordingly, if Figures 8 to 10 As shown, for any arc surface on the edge surface 33 (such as the second arc surface 335, the transition arc surface 336, and the first arc surface 337), it is substantially tangent to the main side surface 31 connected to one side of the arc surface, and substantially tangent to the side surface 32 connected to the other side of the arc surface. Specifically, the arc surface (such as Fig. 9 and Fig.10 033 surface in the figure) and the main side surface 31 connected to one side of the arc surface (such as Fig. 9 and Fig.10 The 013 surface in the arc surface is basically tangent (forming a tangent line L3) and connected to the side surface 32 on the other side of the arc surface (such as Fig. 9 and Fig.10 023 surface in the figure) are basically tangent (forming tangent line L4).

[0157] In the embodiment of the present invention, for any arc surface on the edge surface 33, the arc radius (such as R 335 , R 336 , R 337 Specifically, it may refer to the radius of the arc curve B corresponding to the arc surface, such as Fig.10 As shown, the center O2 of the arc curve B is the intersection of the perpendicular line T3 of the tangent line L3 and the perpendicular line T4 of the tangent line L4. The arc radius r2 (such as R 335 , R 336 , R 337 ) is the distance from the center O2 to the tangent line L3 (or tangent line L4).

[0158] In the embodiment of the present invention, for any edge face 33, the length L of the second arc surface 335 located at the opposite ends of the first arc surface 337 is 335 The arc radius R of the second arc surface 335 at the two opposite ends of the first arc surface 337 may be the same or different. 335 The lengths L of the transition arc surfaces 336 at the two opposite ends of the first arc surface 337 may be the same or different. 336 Can be the same or different.

[0159] In the embodiment of the present invention, when the mold core 3 includes a plurality of facets 33, the length L of the first arc surface 337 of every two facets 33 is 337 The arc radius R of the first arc surface 337 of each two edge faces 33 may be the same or different. 337 The length L of the second curved surface 335 of each two edge faces 33 may be the same or different. 335 The arc radius R of the second arc surface 335 of each two edge faces 33 may be the same or different. 335 The length L of the transition arc surface 336 between each two edge faces 33 may be the same or different. 336 Can be the same or different.

[0160] In the embodiment of the present invention, the mold core 3 may be formed of conventional mold core 3 materials in the art, and there is no particular limitation on this.

[0161] The present invention is further described below through specific embodiments.

[0162] Example 1

[0163] 1. Preparation of positive electrode

[0164] After the conductive agent and PVDF glue are evenly mixed, lithium cobalt oxide is added, and N-methylpyrrolidone (NMP) is added thereto, and stirred evenly to obtain a positive electrode slurry; wherein the mass ratio of lithium cobalt oxide, PVDF, and conductive agent is 97.6:1.05:1.35, and the conductive agent is composed of conductive carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes in a mass ratio of 4:1:5;

[0165] The positive electrode slurry is coated on the front and back surfaces of the aluminum foil, and after baking and rolling, a positive electrode active material layer is formed on the front and back surfaces of the aluminum foil, and then cut to obtain a positive electrode sheet.

[0166] 2. Preparation of negative electrode sheet

[0167] After the conductive carbon black and graphite powder are mixed evenly, deionized water, carboxymethyl cellulose and styrene-butadiene rubber are added respectively, and stirred evenly to obtain a negative electrode slurry; wherein the mass ratio of the conductive carbon black, graphite powder, carboxymethyl cellulose and styrene-butadiene rubber is 0.5:97:1.3:1.2;

[0168] The negative electrode slurry is coated on the front and back surfaces of the carbon-coated copper foil, and after baking and rolling, a negative electrode active material layer is formed on the front and back surfaces of the carbon-coated copper foil, and then cut to obtain a negative electrode sheet.

[0169] 3. Preparation of batteries

[0170] The positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence and then wound to form a winding core;

[0171] The mold core 3 is used to punch the aluminum-plastic film with a thickness of 113 μm into a film shell 1; wherein the difference between the length of the mold core 3 and the length of the winding core (PA GAP) is 0.4 mm, and the difference between the width of the mold core and the width of the winding core (P-JR GAP) is 1.3 mm; the thickness of the winding core T=5 mm;

[0172] After the roll core is placed in the cavity 100 of the film shell 1, the lithium-ion battery is obtained through the processes of packaging, baking, liquid injection (i.e., injection of electrolyte), formation, sorting, secondary sealing, open circuit voltage test (OCV) and packaging;

[0173] The electrolyte preparation process is as follows: in a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are mixed in a mass ratio of EC:EMC:DEC=30:50:20, and then lithium hexafluorophosphate (LiPF6) is added thereto and mixed evenly to obtain an electrolyte with a LiPF6 concentration of 1.15 mol / L.

[0174] Specifically, the structural diagram of a lithium-ion battery is as follows: Figures 1 to 7 As shown, the battery cell 2 is located in the cavity 100 of the membrane shell 1, and the membrane shell 1 has a first main body and a second main body 14. The first main body includes a first side portion 11, an edge portion 12, an edge wall 13 connected between the first side portion 11 and the edge portion 12, and an extension portion 15 connected to the side of the edge portion 12 away from the first side portion 11 and extending outward in a direction away from the cavity 100. The second main body 14 and the first side portion 11 are respectively located on opposite sides of the thickness direction (third direction z) of the winding core (or cavity 100), and the second main body 14 is connected to the extension portion 15 to form an edge seal of the membrane shell 1, which includes a top edge seal located on one side of the membrane shell 1 in the length direction (first direction x) of the membrane shell 1, and side edge seals located on opposite sides of the membrane shell 1 in the width direction (second direction y) of the membrane shell 1.

[0175] Among them, the width direction of the electrode sheet (positive electrode sheet, negative electrode sheet) and the length direction (first direction x) of the battery cell 2 are parallel to each other, the length direction of the electrode sheet (positive electrode sheet, negative electrode sheet) and the width direction (second direction y) of the battery cell 2 are parallel to each other, the bending section 202 of the electrode sheet (the first bending section of the positive electrode sheet, the second bending section of the negative electrode sheet) is located on the opposite sides of the width direction (second direction y) of the battery cell 2, and the end surface 200 of the electrode sheet is exposed on the opposite sides of the length direction (first direction x) of the battery cell 2.

[0176] The battery cell 2 includes a positive electrode tab 211 connected to the positive electrode sheet, and a negative electrode tab 221 connected to the negative electrode sheet. The positive electrode tab 211 and the negative electrode tab 221 extend out of the membrane shell 1 from the top sealing edge respectively, and at the top sealing edge, the extension portion 15 of the first main body of the membrane shell 1 is located on one side of the thickness direction (third direction z) of the positive electrode tab 211, and the second main body 14 is located on the other side of the thickness direction (third direction z) of the positive electrode tab 211, the extension portion 15 of the first main body of the membrane shell 1 is located on one side of the thickness direction (third direction z) of the negative electrode tab 221, and the second main body 14 is located on the other side of the thickness direction (third direction z) of the negative electrode tab 221.

[0177] The first main body of the membrane shell 1 includes four side portions 12 distributed along the circumference of the first main body, namely a first side portion 121, a second side portion 122, a third side portion 123 and a fourth side portion 124; the first main body of the membrane shell 1 includes four prism walls 13, namely a first prism wall 131 connected between the first side portion 11 and the first side portion 121, a second prism wall 132 connected between the first side portion 11 and the second side portion 122, a third prism wall 133 connected between the first side portion 11 and the third side portion 123, and a fourth prism wall 134 connected between the first side portion 11 and the fourth side portion 124.

[0178] Each prism 13 includes a first arc segment 137, second arc segments 135 located at opposite ends of the first arc segment 137, and a transition arc segment 136 connected between the first arc segment 137 and the second arc segment 135. The arc radius R of the first arc segment 137 is 137 Greater than the arc radius R of the second arc segment 135 135 , the arc radius R of the transition arc segment 136 136 The radius R of the arc between the second arc segment 135 135 The arc radius R of the first arc segment 137 137 and gradually increases along the direction from the second arc segment 135 to the first arc segment 137 (the arc radius R of the transition arc segment 136 at one end close to the second arc segment 135) 136 The arc radius R is substantially equal to the second arc segment 135 135 The arc radius of the transition arc segment 136 close to the first arc segment 137 is substantially equal to the arc radius R of the first arc segment 137. 137 ), the second arc segments 135 of each two adjacent edge walls 13 are connected by an arc portion.

[0179] For any prism 13, the length L of the second arc segment 135 located at the two opposite ends of the first arc segment 137 is 135 The arc radius R of the second arc segment 135 located at the opposite ends of the first arc segment 137 is substantially the same. 135 The lengths L of the transition arc segments 136 at the two opposite ends of the first arc segment 137 are substantially the same. 136 Basically the same.

[0180] The length L of the first arc segment 137 of each of the two prism walls 13 is 137 The arc radius R of the first arc segment 137 of each of the two prism walls 13 is substantially the same. 137 The length L of the second arc segment 135 of each two prism walls 13 is substantially the same. 135 The arc radius R of the second arc segment 135 of each of the two prism walls 13 is substantially the same. 135 The length L of the transition arc 136 between each two prism walls 13 is substantially the same. 136Basically the same.

[0181] Specifically, in the process of punching the aluminum-plastic film into the film shell 1, the mold core 3 used has a structure corresponding to the above-mentioned film shell 1 (the structural schematic diagram of the mold core 3 is shown in FIG. Figures 8 to 10 As shown), it includes a main side surface 31, a side surface 32, and an edge surface 33 connected between the main side surface 31 and the side surface 32. The number of the side surfaces 32 is four, which are respectively a first side surface 321 corresponding to the first side portion 121, a second side surface 322 corresponding to the second side portion 122, a third side surface corresponding to the third side portion 123, and a fourth side surface corresponding to the fourth side portion 124. The number of the edge surfaces 33 is four, which are respectively a first edge surface 331 corresponding to the first prism 131, a second edge surface 332 corresponding to the second prism 132, a third edge surface 333 corresponding to the third prism 133, and a fourth edge surface 334 corresponding to the fourth prism 134. Each edge surface 33 has a first curved surface 337 corresponding to the corresponding prism 13, second curved surfaces 335 located at opposite ends of the first curved surface 337, and a transition curved surface 336 located between the second curved surface 335 and the first curved surface 337.

[0182] The second arc surface 335 of each two adjacent edge surfaces 33 is connected by an arc surface. The edge surfaces 33 (first edge surface 331, third edge surface 333) located on either side of the length direction (first direction x) of the membrane shell 1 are approximately 95% of the length of the core 3, and the edge surfaces 33 (second edge surface 332, fourth edge surface 334) located on either side of the width direction (first direction x) of the membrane shell 1 are approximately 95% of the width of the core 3.

[0183] The core 3 also includes a recessed area 300 located on the same side of the thickness direction of the core 3 as the main side 31. The recessed area 300 does not penetrate the core 3 in the thickness direction of the core 3. The main side 31 is arranged on the circumferential side of the recessed area 300, and the edge surface 33 is located on the side of the main side 31 away from the recessed area 300.

[0184] For any edge face 33, the arc radius R of the transition arc face 336 is 336 The arc radius R3 of the second arc surface 335 135 and the arc radius R of the first arc surface 337 337 The arc radius of the transition arc surface 336 close to the first arc surface 337 is substantially equal to the arc radius R of the first arc surface 337. 337 , the arc radius R of the transition arc surface 336 336 The width of the arc gradually increases along the direction from the second arc surface 335 to the first arc surface 337 .

[0185] For any edge face 33, the length L of the second arc surface 335 located at the two opposite ends of the first arc surface 337 is335 The arc radius R of the second arc surface 335 located at the opposite ends of the first arc surface 337 is substantially the same. 335 The length L of the transition arc surface 336 at the two opposite ends of the first arc surface 337 is substantially the same. 336 Basically the same.

[0186] The length L of the first arc surface 337 of each of the two edge surfaces 33 is 337 The arc radius R of the first arc surface 337 of each two edge faces 33 is substantially the same. 337 The length L of the second arc surface 335 of each two edge faces 33 is substantially the same. 335 The arc radius R of the second arc surface 335 of each two edge faces 33 is substantially the same. 335 The length L of the transition arc surface 336 between every two edge faces 33 is substantially the same. 336 Basically the same.

[0187] For any edge face 33, the length L of the edge face 33 is 33 It is substantially equal to the length L of the edge wall 13 corresponding to the edge face 33 in the membrane shell 1. 13 , the length L of the first arc surface 337 337 is substantially equal to the length L of the first arc segment 137 corresponding to the first arc surface 337 in the membrane shell 1 137 , the arc radius R of the first arc surface 337 337 The radius R of the first arc segment 137 corresponding to the first arc surface 337 is substantially equal to 137 , the length L of the second arc surface 335 335 is substantially equal to the length L of the second arc segment 135 corresponding to the second arc surface 335 in the membrane shell 1 135 , the arc radius R of the second arc surface 335 335 The arc radius R is substantially equal to the arc radius R of the second arc segment 135 corresponding to the first arc surface 337. 135 , the length L of the transition arc surface 336 336 is substantially equal to the length L of the transition arc segment 136 corresponding to the transition arc surface 336 in the membrane shell 1. 136 .

[0188] Embodiments 2 to 34: The difference from Embodiment 1 is that the arc radius R of the second arc surface 335 of the top / bottom edge surface 33 (first edge surface 331 and third edge surface 333) and the side edge surface 33 (second edge surface 332 and fourth edge surface 334) of the mold core 3 is 335 , the arc radius R of the first arc surface 337 337 , the ratio of the length of the second curved surface 335 to the length of the mold core 3 in the length direction of the edge surface 33 where the second curved surface 335 is located (L 335 / L30 ), the ratio of the length of the transition arc surface 336 to the length of the core 3 in the length direction of the edge surface 33 where the transition arc surface 336 is located (L 336 / L 30 ), the ratio of the length of the first curved surface 337 to the length of the core 3 in the length direction of the edge surface 33 where the first curved surface 337 is located (L 337 / L 30 ) and other conditions are different, accordingly, the arc radius R of the second arc segment 135 of the edge wall 13 (the first edge wall 131 and the third edge wall 133) of the top / bottom edge of the membrane shell 1 and the edge wall 13 (the second edge wall 132 and the fourth edge wall 134) of the side edge 135 , the arc radius R of the first arc segment 137 137 , the ratio of the length of the second arc segment 135 to the length of the prism wall 13 where it is located (L 135 / L 13 ), the ratio of the length of the transition arc segment 136 to the length of the prism wall 13 where it is located (L 136 / L 13 ), the ratio of the length of the first arc segment 137 to the length of the prism wall 13 where it is located (L 137 / L 13 ) and other conditions are different, see Table 1 and Table 2 for details. Except for the differences shown in Table 1, the other conditions are the same as those in Example 1.

[0189] Example 35: The difference from Example 3 is that the battery cell of Example 35 is a laminated battery cell, and the other conditions are the same as those of Example 3.

[0190] Comparative Example 1: The difference from Example 1 is that (1) the arc radius of the side edge wall 13 (the second edge wall 132 and the fourth edge wall 134) of the membrane shell 1 is T / 2 (arc segments with different arc radii are not provided); (2) the arc radius of the top / bottom edge wall 13 (the first edge wall 131 and the third edge wall 133) of the membrane shell 1 is 0.8 (arc segments with different arc radii are not provided); the other conditions are the same as those in Example 1.

[0191] Comparative Example 2: The difference from Example 1 is that (1) P-JR GAP is 0.2 mm, and PA GAP is 1.1 mm; (2) the arc radius of the side edge wall 13 (the second edge wall 132 and the fourth edge wall 134) of the membrane shell 1 is T / 2 (arc segments with different arc radii are not provided); (3) the arc radius of the top / bottom edge wall 13 (the first edge wall 131 and the third edge wall 133) of the membrane shell 1 is 0.8 (arc segments with different arc radii are not provided); the other conditions are the same as those in Example 1.

[0192] Comparative Example 3: The difference from Example 1 is that (1) P-JR GAP is 0.6 mm and PA GAP is 1.5 mm; (2) the arc radius of the side edge wall 13 (the second edge wall 132 and the fourth edge wall 134) of the membrane shell 1 is T / 2 (arc segments with different arc radii are not provided); (3) the arc radius of the top / bottom edge wall 13 (the first edge wall 131 and the third edge wall 133) of the membrane shell 1 is 0.8 (arc segments with different arc radii are not provided); the other conditions are the same as those in Example 1.

[0193] The lithium ion batteries of each embodiment and comparative example were subjected to cycle tests according to the following process. During the cycle tests, the appearance of the batteries was carefully observed, such as the warping of the aluminum-plastic film and the damage of the four corners. In each cycle test, 10 lithium ion batteries were tested for each embodiment and comparative example. The results are shown in Table 2.

[0194] (1) 25°C cycle test: At 25°C, charge to 4.5V at 1.5C rate, and then discharge to 3.0V at 0.5C rate; perform charge and discharge cycles according to this process to detect the number of cycles when the edge of the lithium-ion battery is warped, or detect whether the edge of the lithium-ion battery is warped after 1200 cycles, and detect whether the battery has corner cracks after 1000 cycles, or detect the number of cycles when corner cracks (corner breaks) occur.

[0195] (2) 45°C cycle test: At 45°C, charge to 4.5V at 1.8C rate, and then discharge to 3.0V at 0.8C rate; perform charge and discharge cycles according to this process to detect the number of cycles when the edge of the lithium-ion battery is warped, or detect whether the edge of the lithium-ion battery is warped after 1200 cycles, and detect whether the battery has corner cracks after 800 cycles, or detect the number of cycles when corner cracks (corner breaks) occur.

[0196] The edge warping means that in the thickness direction of the lithium-ion battery (from the first side portion to the second main body portion (or from the second main body portion to the first side portion)), the raised (convex) portion of the edge wall exceeds the outer surface of the first side portion, resulting in an excessively thick battery.

[0197] (3) After the core is placed in the cavity 100 of the membrane shell 1 and the lithium-ion battery is obtained through packaging and other processes, the appearance of the lithium-ion battery is observed and the area of ​​the region where the battery membrane shell is wrinkled (the membrane shell wrinkle area in Table 1) is detected. The smaller the wrinkle area, the better the battery appearance and the easier the packaging process is to operate, wherein: (1) the wrinkle area S ≤ 2 mm 2 When the core is packaged into the shell, it means that the packaging process of the core is normal. After packaging, the battery appearance is good; (2) The wrinkle area S is 2mm 2 <S≤4mm 2, indicating that the process of packaging the core into the shell is slightly difficult (relatively greater pressure needs to be applied to the battery cell to press the battery cell into the cavity of the membrane shell), and the battery appearance has slight wrinkles; (3) The wrinkle area S>4mm 2 The core-to-shell packaging process is difficult (a relatively larger pressure needs to be applied to the battery cell to press the battery cell into the cavity of the membrane shell), and the battery appearance has obvious wrinkles.

[0198] Table 1 Related parameters of the edge wall of the membrane shell side and the edge surface of the core side

[0199]

[0200] Table 2 Related parameters of the edge wall of the top / bottom edge of the membrane shell and the edge surface of the top / bottom edge of the core

[0201]

[0202] Table 3 Test results

[0203]

[0204] It can be seen from Comparative Examples 1 to 3 that when P-JR GAP and PA GAP are small, the battery membrane shell is prone to corner cracks during the battery cycle, and when P-JR GAP and PA GAP are large, the battery membrane shell is prone to warping during the battery cycle, causing the battery to be too thick. The corner cracks and warping problems of the battery membrane shell affect the battery cycle performance.

[0205] Compared with Comparative Examples 1 to 3, in Examples 1 to 35, the edges of the mold core are designed with different arc radii (the edges include a large arc surface, small arc surfaces located at opposite ends of the large arc surface, and a transition arc surface located between the small arc surface and the large arc surface), so that in the membrane shell of the manufactured lithium-ion battery, the edge wall connected between the first side portion and the edge portion has a corresponding different arc radius design (the edge wall includes a large arc segment, a second arc segment located at opposite ends of the first arc segment, and a transition arc segment located between the small arc segment and the large arc segment), which can solve the problems of corner cracks and warping of the battery membrane shell and improve the cycle life of the battery.

[0206] Furthermore, compared with Example 9, Examples 3, 6 to 8 control the R of the side edge of the mold core. 337 In the range of T / 2-A to T / 2+B, the R of the side edge of the membrane shell is 137 In the range of T / 2-A to T / 2+B, it is beneficial to solve the problems of corner cracking and warping of the battery membrane shell, and is also beneficial to the packaging of the battery cell.

[0207] Furthermore, compared with Embodiment 6, Embodiment 7 and Embodiment 9, Embodiment 3 and Embodiment 8 further control the R of the side edge surface of the mold core.337 In the range of T / 2~T / 2+B, the R of the side edge of the membrane shell is 137 Within the range of T / 2 to T / 2+B, it is beneficial to further improve the corner cracking and warping problems of the battery membrane shell, increase the battery cycle life, and facilitate the packaging of the battery cell.

[0208] Furthermore, compared with Example 11, Examples 3, 10, and 12 to 13 further control the R of the side edge of the mold core. 335 In the range of T / 2-A~T / 2, the R of the side edge of the membrane shell is 135 In the range of T / 2-A to T / 2, it is beneficial to further improve the corner cracking and warping problems of the battery membrane shell, increase the battery cycle life, and facilitate the packaging of the battery cell.

[0209] Furthermore, compared with Example 14, Examples 3, 10, and 12 to 13 further control the R of the side edge of the mold core. 337 / R 335 When 1<R 337 / R 335 ≤5, so that the side edge wall of the membrane shell R 137 / R 135 When 1<R 137 / R 135 Within the range of ≤5, it is beneficial to further improve the corner cracking and warping problems of the battery membrane shell, increase the battery cycle life, and facilitate the packaging of the battery cell.

[0210] Furthermore, compared with Example 15 and Example 18, Example 3, Example 16 and Example 17 further control the L of the side edge of the mold core. 337 / L 30 In the range of 30% to 70%, the L of the side edge of the membrane shell is 137 / L 13 In the range of 30% to 74%, it is beneficial to further improve the corner cracking and warping problems of the battery membrane shell, increase the battery cycle life, and facilitate the packaging of the battery cell.

[0211] Furthermore, compared with Example 19 and Example 30, Example 3 and Examples 20 to 29 further control the R of the top edge of the mold core. 337 In the range of 0.8 to 5 mm, R 335 In the range of 0.2 to 1.5 mm, the R of the side edge of the membrane shell 137 In the range of 0.8 to 5 mm, R 335 Within the range of 0.2 to 1.5 mm, it is beneficial to further improve the corner cracking and warping problems of the battery membrane shell and increase the battery cycle life.

[0212] Furthermore, compared with Example 24, Examples 3 and Examples 20 to 29 further control the R of the top edge of the mold core. 337 / R 335 When 1<R 337 / R 335 ≤8, so that the side edge wall of the membrane shell R 137 / R 135 When 1<R 137 / R 135 Within the range of ≤8, it is beneficial to improve the corner cracking and warping problems of the battery membrane shell while facilitating the packaging of the battery cell.

[0213] Furthermore, compared with Example 31 and Example 34, Example 3, Example 32 and Example 33 further control the L of the top edge of the mold core. 337 / L 30 In the range of 30% to 70%, the L of the top edge of the membrane shell is 137 / L 13 In the range of 30% to 74%, it is beneficial to further improve the corner cracking and warping problems of the battery membrane shell, increase the battery cycle life, and facilitate the packaging of the battery cell.

[0214] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A membrane shell, characterized in that: The invention comprises a first side portion, an edge portion, and an edge wall connected between the first side portion and the edge portion, wherein the edge wall comprises a first arc segment, second arc segments located at opposite ends of the first arc segment, and a transition arc segment connected between the first arc segment and the second arc segment, and the arc radius R of the first arc segment is 137 is greater than the arc radius R of the second arc segment 135 .

2. The membrane housing according to claim 1, characterized in that The ratio of the length of the second arc segment to the length of the prism wall is 10% to 32%; And / or, the ratio of the length of the transition arc segment to the length of the prism wall is 5% to 27%; And / or, the ratio of the length of the first arc segment to the length of the prism wall is 30% to 74%.

3. The membrane housing according to claim 1, characterized in that The arc radius R of the transition arc segment 136 The radius R of the arc between the second arc segment 135 The arc radius R of the first arc segment 137 and increases along the direction from the second arc segment to the first arc segment.

4. The membrane housing according to claim 1, characterized in that The membrane shell includes the edge portion located on at least one side of the membrane shell in the first direction, and the edge portion located on at least one side of the membrane shell in the second direction, each edge portion is connected to the first side portion with the edge wall, and the first direction intersects with the second direction; The edge wall existing on either side of the membrane shell in the first direction satisfies: 1<R 137 / R 135 ≤8, preferably 1<R 137 / R 135 ≤5; and / or, R 135 0.2-1.5 mm, preferably 0.4-1 mm; and / or, R 137 0.8~5mm; And / or, the arc radius R of the transition arc segment 136 Between 0.2mm and 5mm.

5. The membrane housing according to claim 4, characterized in that The edge wall present on either side of the membrane shell in the second direction satisfies: 1<R 137 / R 135 ≤5; and / or, R 135 H / 2-A~H / 2+A; and / or, R 137 H / 2-A~H / 2+B; And / or, the arc radius R of the transition arc segment 136 Between H / 2-A and H / 2+B; Wherein, A is 0.5~2H / 5, B is 0.5~2H / 5, H is the depth of the cavity of the membrane shell, R 135 , R 136 , R 137 The units of A and H are mm.

6. The membrane housing according to any one of claims 1 to 5, characterized in that: The membrane shell includes a first main body and a second main body connected to each other, at least one of the first main body and the second main body has a cavity, and the first side portion, the edge portion and the edge wall connected between the first side portion and the edge portion that surround the cavity.

7. A battery, characterized in that: It comprises the membrane shell according to any one of claims 1 to 6, and a battery cell located in the membrane shell.

8. The battery according to claim 7, characterized in that The battery core is a laminated battery core or a wound battery core.

9. The battery according to claim 7, characterized in that The battery cell comprises a bent portion, and the bent portion of the battery cell is located at two opposite sides of the battery cell in the second direction, The edge wall located on either side of the membrane shell in the second direction satisfies: 1<R 137 / R 135 ≤5; and / or, R 135 T / 2-A~T / 2+A; and / or, R 137 T / 2-A~T / 2+B; And / or, the arc radius R of the transition arc segment 136 Between T / 2-A and T / 2+B; Wherein, A is 0.5~2T / 5, B is 0.5~2T / 5, T is the thickness of the battery cell, R 135 , R 136 , R 137 The unit of and T is mm.

10. The battery according to any one of claims 7 to 9, characterized in that: The edge wall located on either side of the membrane shell in the first direction satisfies: 1<R 137 / R 135 ≤8, preferably 1<R 137 / R 135 ≤5; and / or, R 135 0.2mm~1.5mm, preferably 0.4~1mm; and / or, R 137 0.8mm~5mm; And / or, the arc radius R of the transition arc segment 136 Between 0.2mm and 5mm.

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