Battery

Abstract

The utility model discloses a battery. The battery comprises a shell and a battery cell, the battery cell is arranged in the shell and comprises an isolating membrane, a plurality of first pole pieces and a plurality of second pole pieces, the isolating membrane, the first pole pieces and the second pole pieces are mutually stacked, the isolating membrane comprises a plurality of layers of separators, and each separator comprises a body part. A transition part and a contraction part. The shrinkage part of the isolating membrane is formed by heating the edge of the isolating membrane to shrink, and the isolating membrane is heated and shrunk, so that the size of the isolating membrane is reduced, the risk that the isolating membrane extends out relative to the shell after the battery cell is put into the shell is reduced, the probability of pseudo soldering caused by the extending isolating membrane when the shell cover is welded is reduced, and the welding quality of the shell cover is improved. And moreover, due to heating, the adjacent shrinkage parts are mutually welded, and the bonding force generated between the welded shrinkage parts can also control the isolating membrane to reduce the probability of short circuit in the battery cell caused by shrinkage during subsequent heating test or use, so that the yield of the product is improved.

Description

Technical Field

[0001] The utility model relates to the field of battery processing, in particular to a battery. Background Art

[0002] A laminated cell is a common type of cell, which is made by stacking cathode sheets, separators, and anode sheets in sequence. Batteries using this type of cell are packaged by placing the cell in a shell. After the cell is placed in the shell, the separator will fold over, and the folded portion of the separator will be exposed at the opening of the discharge cell. This portion of the separator will affect the final packaging of the shell, interfering with the welding process of the opening and the shell cover, resulting in a cold weld on the shell cover. The separator may also shrink during subsequent testing or use, causing the positive and negative electrodes to contact, resulting in an internal short circuit in the cell, reducing the product yield. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a battery that can reduce the impact of the separator on the welding of the shell and reduce the risk of internal short circuits in the battery cell, thereby improving the product yield.

[0004] According to an embodiment of the present invention, a battery comprises a shell and a battery cell, wherein the battery cell is arranged inside the shell, and the battery cell comprises an isolation membrane, a plurality of first pole pieces, and a plurality of second pole pieces stacked on each other, the isolation membrane comprises a multilayer separator, and the separator comprises a main body portion, a transition portion, and a contraction portion. A main body portion is provided between adjacent first and second pole pieces, the transition portion is connected to the edge of the main body portion, and in the stacking direction of the first and second pole pieces, the two adjacent transition portions jointly wrap at least one side edge of the second pole piece, and the contraction portion is connected to the side edge of the transition portion away from the main body portion, and in the stacking direction of the first and second pole pieces, at least two adjacent contraction portions are connected to each other.

[0005] The battery according to the embodiment of the present invention has at least the following beneficial effects: the shrinkage portion of the isolation membrane is formed by heating the edge of the isolation membrane to shrink it. Since the isolation membrane is heated and shrunk, the size of the isolation membrane becomes smaller than the size of the isolation membrane that has not been pre-treated by heating, thereby reducing the risk of the isolation membrane extending relative to the shell after the battery cell is placed in the shell, thereby reducing the probability of cold welding caused by the protruding isolation membrane when the shell cover is welded, and due to the heating, some adjacent shrinkage portions are welded to each other. The bonding force generated between the shrinkage portions after welding can also restrain the isolation membrane to reduce the probability of short circuit in the battery cell due to shrinkage during subsequent heating testing or use, thereby improving the yield of the product.

[0006] According to some embodiments of the present invention, the bonding force F between two mutually connected contraction parts satisfies: 0<F<10N / mm.

[0007] According to some embodiments of the present invention, one end of the contraction portion used to connect the transition portion is the inner end of the contraction portion, and the angle between the tangent of the contraction portion at the inner end and the plane where the second pole piece is located is the wrap angle, 0°<wrapping angle<90°; preferably, 20°≤wrapping angle≤65°.

[0008] According to some embodiments of the present invention, the wrap angle is 20°≤65°.

[0009] According to some embodiments of the present invention, the battery also includes a first pole ear, which is connected to the first pole piece, the main body includes a first edge and a second edge relative to each other, and a third edge and a fourth edge relative to each other, the first pole ear protrudes relative to the fourth edge, the entire area of ​​the first edge, the second edge and the third edge is provided with a contraction portion, and at least a portion of the fourth edge is provided with a contraction portion.

[0010] According to some embodiments of the present invention, a protruding dimension of the isolation film relative to the first pole piece along the length direction of the battery cell is L1, and 0.1 mm ≤ L1 < 3 mm.

[0011] According to some embodiments of the present invention, a protruding dimension of the isolation film relative to the first pole piece along the width direction of the battery cell is L2, and 0.1 mm ≤ L2 < 1 mm.

[0012] According to some embodiments of the present invention, the corners of the isolation membrane and the first pole piece are rounded, the rounded corner radius of the isolation membrane is R1, the rounded corner radius of the first pole piece is R2, and R1≤R2+L2.

[0013] According to some embodiments of the present invention, along the width direction of the battery core, the distance between the inner wall of the shell and the outer edge of the corresponding isolation membrane is L3, and L3≥0.

[0014] According to some embodiments of the present invention, along the width direction of the battery cell, the distance between the inner wall of the shell and the outer edge of the corresponding isolation membrane is L3, and the distance between the inner wall of the shell and the outer edge of the corresponding first pole piece is L4, 0mm≤L3<(L4-0.1)mm.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0017] Figure 1 It is a front view of the battery cell in the first embodiment of the present utility model;

[0018] Figure 2 A front view of a battery in one embodiment of the present invention;

[0019] Figure 3 A top view of a battery cell in one embodiment of the present invention;

[0020] Figure 4 It is a front view of a battery cell according to a first embodiment of the prior art;

[0021] Figure 5 It is a front view of a battery in the prior art;

[0022] Figure 6 A top view of a battery cell in the prior art;

[0023] Figure 7 A top view of a battery cell housed in a housing in one embodiment of the present invention;

[0024] Figure 8 A top view of a special-shaped battery cell in the prior art;

[0025] Figure 9 It is a front view of a battery cell according to a second embodiment of the prior art;

[0026] Figure 10 It is a front view of the battery cell in the second embodiment of the present invention.

[0027] Figure numerals: battery cell 100, first pole piece 101, second pole piece 102, isolation membrane 103, main body 104, transition portion 105, contraction portion 106, single-sided sheet 107, double-sided sheet 108, adhesive 109, first side 110, second side 111, wrapping angle 112, battery 200, shell 201, storage cavity 202, first pole ear 301, second pole ear 302, first edge 303, second edge 304, third edge 305, fourth edge 306. DETAILED DESCRIPTION

[0028] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0029] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0030] In the description of this utility model, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of the terms "first" and "second" is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0031] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0032] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0033] refer to Figure 1 and Figure 2The battery 200 according to the embodiment of the first aspect of the present utility model includes a shell 201 and a battery cell 100. The battery cell 100 is arranged inside the shell 201. The battery cell 100 includes an isolation membrane 103, a plurality of first pole pieces 101 and a plurality of second pole pieces 102 stacked on each other. The isolation membrane 103 includes a multi-layer separator. The separator includes a main body 104, a transition portion 105 and a contraction portion 106. A main body 104 is provided between an adjacent first pole piece 101 and a second pole piece 102. The transition portion 105 is connected to the edge of the main body 104. In the stacking direction of the first pole piece 101 and the second pole piece 102, the two adjacent transition portions 105 jointly wrap at least one side edge of the second pole piece 102. The contraction portion 106 is connected to the side edge of the transition portion 105 away from the main body 104. In the stacking direction of the first pole piece 101 and the second pole piece 102, at least two adjacent contraction portions 106 are connected to each other. Reference Figures 4 to 6 , Figure 4 The structure diagram of the laminated battery cell 100 in the prior art is shown in FIG. In the figure, the isolation film 103 is relatively flat. In order to avoid the first electrode 101 and the second electrode 102 from contacting each other and causing a short circuit, the extension distance is also relatively long. Figure 5 and Figure 6 As shown, after the battery cell 100 is placed in the housing 201, the isolation film 103 will protrude more relative to the housing 201. This part of the isolation film 103 will interfere with the welding position of the opening on the housing 201, causing a cold weld during the packaging welding of the housing 201. In the embodiment of the present invention, after the edge of the isolation film 103 is heat-treated to form a shrinkage portion 106, as shown in FIG. Figure 3 As shown, the protruding size of the first electrode 101 is smaller than that of the untreated isolation film 103, and is less likely to protrude when placed in the shell 201, thereby reducing the probability of cold solder joints caused by the protrusion of the isolation film 103. In addition, due to the heating, some adjacent shrinkage parts 106 are welded to each other. The bonding force generated between the shrinkage parts 106 after welding can also restrain the isolation film 103, reducing the probability of short circuit in the battery cell 100 caused by shrinkage during subsequent heating tests or use, thereby improving the product yield.

[0034] It should be noted that the reference Figure 8 In some embodiments of the present invention, it is also possible to Figure 8 The isolation film 103 of the special-shaped battery cell 100 shown in the figure is processed, which can also reduce the probability of the isolation film 103 causing a cold solder joint and causing a short circuit in the battery cell 100. It should be noted that there are many ways to stack the isolation film in the battery cell 100, in addition to Figure 1 and Figure 4 The bag-making lamination shown in FIG. 1 can also use a Z-shaped lamination (such as Figure 9 and Figure 10As shown) and multiple isolation membranes are alternately stacked, the battery cell 100 of the embodiment of the present invention is applicable to the above-mentioned multiple isolation membrane stacking methods.

[0035] It should be noted that the reference Figure 1 and Figure 2 In some embodiments of the present invention, the shrinkage portion 106 of the isolation film 103 is formed by heating the edge of the isolation film 103 to shrink it. Due to the shrinkage portion 106, when performing a hot box test, the isolation film 103 that has shrunk once under high temperature has a smaller shrinkage amplitude than the isolation film 103 that has not undergone heating pretreatment. This can effectively avoid the positive and negative electrode sheets from contacting each other due to the shrinkage of the isolation film 103 during the hot box test, thereby improving the pass rate of the battery 200 in passing the hot box test.

[0036] It should be noted that the reference Figure 1 In some embodiments of the present invention, the first electrode 101 is an anode electrode, the second electrode 102 is a cathode electrode, and the first electrode 101 extends relative to the second electrode 102. The charge is mainly released by the anode. Therefore, the anode electrode is longer and wider than the cathode electrode and can accommodate more ions to maintain good electrochemical performance.

[0037] It should be noted that the reference Figure 1 In some embodiments of the present invention, the first electrode 101 includes a single-sided sheet 107 and a double-sided sheet 108. The single-sided sheet 107 is coated with an active material layer only on the side facing the second electrode 102, and the double-sided sheet 108 is coated with an active material layer on both sides, which can improve energy density and energy utilization.

[0038] refer to Figure 1 In some embodiments of the present invention, the bonding force F between the two mutually connected shrinkage parts 106 satisfies the following: 0<F<10N / mm. This design allows the isolation films 103 of different layers to be bonded together. The bonding force generated between them can, on the one hand, provide mutual binding force between the isolation films 103 during the hot box test of the battery cell 100, making the isolation films 103 less likely to shrink at high temperatures, further improving the pass rate of the hot box test; on the other hand, Figure 1As shown, the bending generated by the shrinking portion 106 during shrinkage and bonding further reduces the extension length relative to the first pole piece 101, thereby preventing the separator 103 from extending relative to the housing 201 after the battery cell 100 is placed in the housing 201 during the manufacturing process of the battery 200, thereby improving the quality of the battery 200. It should be noted that in order to generate bonding force between the separators 103, it is preferred to heat treat the shrinking portion 106. This will cause the separators 103 to shrink and melt to a certain extent. The adjacent separators 103 will heat up, melt, cool down, and then weld together after cooling down again, generating bonding force between each other. This process achieves two goals in one step, improving processing efficiency. The bonding force can also be achieved by adding chemical materials such as adhesives between the separators 103 to achieve bonding. The reason why the bonding force F is controlled within the range of 0~10N / mm is that if the bonding force is to be greater than 10N / mm, a long heat treatment period is required or an adhesive needs to be added between the isolation film 103. Such a process is cumbersome and a long heat treatment period may cause the isolation film 103 to shrink too much, and then the first electrode 101 and the second electrode 102 may contact and cause a short circuit.

[0039] It should be noted that, in some embodiments of the present invention, the isolation film 103 in the lamination process of the battery cell 100 can be as follows: Figure 4 The multi-sheet stacking shown in FIG. 1 may also be a stacking of a long sheet of isolation film 103 in a Z-shaped staggered manner (eg, Figure 9 and Figure 10 As shown), and the first pole piece 101 and the second pole piece 102 are alternately placed therein to form a battery cell 100. The battery cell 100 formed in both ways can be finally formed as shown by heat treatment on the edge of the isolation film 103. Figure 1 The status shown in .

[0040] refer to Figure 1 In some embodiments of the present invention, the end of the constricted portion 106 that connects to the transition portion 105 is the inner end of the constricted portion 106 . The angle between the tangent line at the inner end of the constricted portion 106 and the plane of the second pole piece 102 is the wrap angle 112 , where 0° < wrap angle 112 < 90°; preferably, 20° ≤ wrap angle 112 ≤ 65°. Providing a certain degree of curvature to the constricted portion 106 can reduce the length of the separator 103 that ultimately extends relative to the first pole piece 101, thereby reducing the likelihood of interference between the separator 103 and the opening of the housing 201 after the battery cell 100 is placed in the housing 201, thereby affecting the soldering process.

[0041] refer to Figure 3In some embodiments of the present invention, the battery 200 further includes a first tab 301 connected to the first electrode sheet 101. The body 104 includes opposing first and second edges 303, 304, and opposing third and fourth edges 305, 306. The first tab 301 protrudes relative to the fourth edge 306. A constriction 106 is provided across the entire first, second, and third edges 303, 304, and 305, and at least a portion of the fourth edge 306 is provided with a constriction 106. The tab serves as a bridge connecting the internal and external circuits of the battery 200. Its electrical conductivity directly affects the charge and discharge efficiency of the battery 200. A good connection between the tab and the electrode sheet ensures smooth transfer of electrical energy from the battery 200 to the external circuit or from the external circuit to the battery 200, thereby improving the charge and discharge efficiency of the battery 200. Therefore, in addition to the first tab 301 connected to the first electrode sheet 101, a second tab 302 is also connected to the second electrode sheet 102. In some embodiments of the present invention, at least a portion of the fourth edge 306 is provided with a contraction portion 106. Figure 3 On both sides of the first and second tabs 301, 302, since the first and second tabs 301, 302 themselves have certain dimensions and need to be welded to the housing 201, a relatively large space is reserved between the tab ends and the housing 201. Therefore, the separator 103 in the middle portion of the first and second tabs 301, 302 does not need to be shrunk, and this portion will not extend outside the housing 201 after the battery cell 100 is placed in the housing 201. Specifically, in some embodiments of the present invention, the distance between the fourth edge 306 and the inner wall edge of the housing 201 is reserved to be more than 2 mm, so there is also sufficient space for the separator 103. However, it should be noted that the portion between the first and second tabs 301, 302 can also be heat-treated to shrink it. This solution is a derivative embodiment of the present invention and has the same technical effect. As for the partial shrinkage portion 106 processed on both sides of the first pole tab 301 and the second pole tab 302, it is to make the structure of the corner part of the battery cell 100 tighter and prevent the processed isolation membrane 103 and the unprocessed isolation membrane 103 from coexisting in the corner part and interfering with each other. At the same time, the processing of the shrinkage portion 106 of the fourth edge 306 does not increase the processing difficulty. The first edge 303 and the left side of the fourth edge 306 are processed together, and the second edge 304 and the right side of the fourth edge 306 are processed together.

[0042] refer to Figure 3In some embodiments of the present invention, the protrusion dimension of the isolation film 103 relative to the first pole piece 101 along the length direction of the battery cell 100 is L1, 0.1mm≤L1<3mm. Specifically, L1 can be 0.1mm, 1.5mm, 2.7mm, etc. It should be noted that the above-mentioned protrusion refers to the dimension of the head of the isolation film 103 protruding relative to the head of the first pole piece 101, or the dimension of the tail of the isolation film 103 protruding relative to the tail of the first pole piece 101. Figure 3 The isolation membrane 103 in the middle is the isolation membrane 103 after the edge has been heat treated. This size range takes into account the dual advantages of safety and avoiding cold welding after being installed in the shell 201. The following is a specific embodiment. When L1 is 0.05mm, the protruding size of the isolation membrane 103 is too small. Although it will not interfere with the shell 201 and will not affect its welding process, the isolation membrane 103 will further shrink during the subsequent hot box test, causing the first pole piece 101 and the second pole piece 102 to contact, thereby causing a short circuit, which poses a safety hazard. When L1 is 1.5mm, the isolation membrane 103 will not interfere with the shell 201. At the same time, it will not cause a short circuit after shrinking during the hot box test. When L1 is 3mm, the distance that the isolation membrane 103 protrudes is still relatively long. No short circuit is caused in the battery cell 100 during the test. However, after the battery cell 100 is installed in the shell 201, the isolation membrane 103 protrudes from the shell 201, affecting the packaging welding step of the shell 201.

[0043]

[0044] It should be noted that the reference Figure 6 In the prior art, the isolation film 103 protrudes relative to the first pole piece 101 by a dimension L5 along the length direction of the battery cell 100 .

[0045] It should be noted that the reference Figure 3 In some embodiments of the present invention, the length direction of the battery cell 100 is the distribution direction of the head and tail as shown in the figure, and the width direction of the battery cell 100 is the left and right distribution direction as shown in the figure.

[0046] According to some embodiments of the present invention, the protrusion of the isolation film 103 relative to the first pole piece 101 along the width direction of the battery cell 100 is L2, 0.1mm≤L2<1mm, specifically, L2 can be 0.1mm, 0.3mm, 0.7mm, etc. It should be noted that the above-mentioned protrusion refers to the protrusion of the left side of the isolation film 103 relative to the left side of the first pole piece 101, or the protrusion of the right side of the isolation film 103 relative to the right side of the first pole piece 101. Figure 3The isolation membrane 103 in the middle is the isolation membrane 103 after the edge has been heat treated. This size range takes into account the dual advantages of safety and avoiding cold welding after being installed in the shell 201. The following is a specific embodiment. When L2 is 0.05mm, the protruding size of the isolation membrane 103 is too small. Although it will not interfere with the shell 201 and will not affect its welding process, the isolation membrane 103 will further shrink during the subsequent hot box test, causing the first pole piece 101 and the second pole piece 102 to contact, thereby causing a short circuit, which poses a safety hazard. When L2 is 0.1mm, the isolation membrane 103 will not interfere with the shell 201. At the same time, it will not cause a short circuit after shrinking during the hot box test. When L2 is 1mm, the distance that the isolation membrane 103 protrudes is still relatively long. No short circuit is caused in the battery cell 100 during the test. However, after the battery cell 100 is installed in the shell 201, the isolation membrane 103 protrudes from the shell 201, affecting the packaging welding step of the shell 201.

[0047]

[0048] It should be noted that the reference Figure 6 In the prior art, the isolation film 103 protrudes relative to the first pole piece 101 along the width direction of the battery cell 100 by a dimension L6.

[0049] It should be noted that the reference Figure 1 and Figure 3 In some embodiments of the present invention, the battery 200 further includes an adhesive 109. The battery cell 100 includes a first side 110 and a second side 111 distributed along the thickness direction. One end of the adhesive 109 is bonded to the first side 110, and the other end of the adhesive 109 is bonded to the second side 111. The adhesive 109 can make the internal connection of the battery cell 100 tighter and improve the structural stability of the battery cell 100. It should be noted that, referring to Figure 1 In some embodiments of the present invention, the adhesive member 109 may be as follows Figure 1 The C-shaped bonding shown in the figure can also continue to extend to the right on the second side 111 and wrap upward from the right side to the right end of the first side 110 to form a surrounding bonding (not shown in the figure). Figure 3 As shown, the adhesive member 109 can be provided with multiple adhesive members 109, and the multiple adhesive members 109 are bonded to the four sides of the battery cell 100, so as to further improve the structural stability of the battery cell 100; the adhesive member 109 can also be provided longer in the length direction, or the adhesive member 109 can be provided longer in the length direction. Figure 3 The adhesive members 109 on the same side are manufactured into a large whole that can stabilize the structure of the battery cell 100. In some embodiments of the present invention, the adhesive member 109 is a single-sided tape, and other adhesive materials can also be used.

[0050] refer to Figure 7In some embodiments of the present invention, the corners of the isolation film 103 and the first pole piece 101 are rounded. The radius of the corner of the isolation film 103 is R1, and the radius of the corner of the first pole piece 101 is R2. R1≤R2+L2. Along the width direction of the battery cell 100, the distance between the inner wall of the shell 201 and the corresponding outer edge of the isolation film 103 is L3, and L3≥0. Figure 3 and Figure 6 In the prior art, the corners of the unprocessed isolation membrane 103 are right angles, which are relatively sharp and prone to burrs after installation. However, the corners of the isolation membrane 103 in this solution are rounded, which makes it easier to place it in the shell 201 and less likely to scratch other components. The above-mentioned restrictions on the fillet radius at the corners of each part are to ensure that the isolation membrane 103 also extends a certain distance relative to the first pole piece 101 at the corner, and at the same time does not interfere with the inner wall of the shell 201 after being inserted into the shell, thereby ensuring the safety performance of the battery cell 100.

[0051] refer to Figure 7 In some embodiments of the present invention, along the width of the battery cell 100, the distance between the inner wall of the housing 201 and the corresponding outer edge of the separator 103 is L3, and the distance between the inner wall of the housing 201 and the corresponding outer edge of the first electrode 101 is L4, where 0 mm ≤ L3 < (L4 - 0.1) mm. This design prevents the battery cell 100 from shaking or falling after being installed in the housing 201. Therefore, the separator 103 is preferably manufactured to fit closely to the inner wall of the housing 201. When L3 ≥ (L4 - 0.1) mm, the margin between the separator 103 and the inner wall of the housing 201 is too large, which can easily cause the battery cell 100 to shake or fall.

[0052] According to the second embodiment of the present invention, the battery manufacturing method includes the following steps:

[0053] The first electrode 101, the second electrode 102 and the isolation membrane 103 are stacked on each other, and the stacked isolation membrane 103 includes a multi-layer separator, which includes a main body 104 arranged between the adjacent first electrode 101 and the second electrode 102, and a transition portion 105 connected to the edge of the main body 104, and a contraction portion 106 connected to the edge of the side of the transition portion 105 away from the main body 104; the contraction portion 106 is heated to shrink the contraction portion 106, and at least two adjacent contraction portions 106 are connected to each other; the battery cell 100 is prepared; and the battery cell 100 is encapsulated in the shell 201.

[0054] refer to Figures 4 to 6 , Figure 4The structure diagram of the laminated battery cell 100 in the prior art is shown in FIG. In the figure, the isolation film 103 is relatively flat. In order to avoid the first electrode 101 and the second electrode 102 from contacting each other and causing a short circuit, the extension distance is also relatively long. Figure 5 and Figure 6 As shown, after the battery cell 100 is placed in the housing 201, the isolation film 103 will protrude more relative to the housing 201. This part of the isolation film 103 will interfere with the welding position of the opening on the housing 201, causing a cold weld during the packaging welding of the housing 201. In the embodiment of the present invention, after the edge of the isolation film 103 is heat-treated to form a shrinkage portion 106, as shown in FIG. Figure 3 As shown, the protruding size of the first electrode 101 is smaller than that of the untreated isolation film 103, and is less likely to protrude when placed in the shell 201, thereby reducing the probability of cold solder joints caused by the protrusion of the isolation film 103. In addition, due to the heating, some adjacent shrinkage parts 106 are welded to each other. The bonding force generated between the shrinkage parts 106 after welding can also restrain the isolation film 103, reducing the probability of short circuit in the battery cell 100 caused by shrinkage during subsequent heating tests or use, thereby improving the product yield.

[0055] It should be noted that the reference Figure 1 In some embodiments of the present invention, the isolation membrane 103 is further processed to shrink and move closer to the middle. Specifically, a heating device with an arc groove can be used to wrap the edge of the battery cell 100 therein, so that the isolation membrane 103 can only shrink and move closer to the middle, solving the problem of the isolation membrane 103 everting, and can further improve the adhesion between the layers of isolation membrane 103.

[0056] In some embodiments of the present invention, the thermal shrinkage temperature of the separator 103 is T1, and the heating temperature of the separator 103 is T2. During the step of heating the shrink portion 106, the heating temperature T2 is set to satisfy the following relationship: 5°C < T2 - T1 < 100°C. It should be noted that the thermal shrinkage temperature T1 refers to the temperature at which the separator 103 begins to shrink due to the influence of temperature, and the heating temperature T2 refers to the temperature at which the separator 103 is heated and curled using an external device. This design is primarily intended to ensure that the separator 103 can achieve the desired shrinkage effect without being damaged. When T2 - T1 ≤ 5°C, the difference between the heating temperature and the thermal shrinkage temperature is too small, resulting in insignificant shrinkage of the separator 103. When T2 - T1 ≥ 100°C, the separator 103 is subjected to excessive temperatures, potentially causing damage or carbonization. This can lead to pores in the separator 103 in the electrode area, impacting the cycling performance of the battery cell 100.

[0057] In some embodiments of the present invention, the base material of the isolation film 103 includes at least one of polyethylene and polypropylene, and 140°C ≤ T2 ≤ 170°C, specifically, the temperature may be 140°C, 150°C, 170°C, etc. Polyethylene and polypropylene have stable chemical properties, good porosity and permeability. As an isolation membrane 103, they can ensure the smooth and efficient operation of the battery cell 100. The preferred heating temperature is to take into account the dual advantages of safety and avoiding cold soldering after installation in the shell 201. When the heating temperature is less than 140°C, the heating temperature is too low, the heating effect is not obvious, the isolation membrane 103 shrinks to a small size, and the distance the isolation membrane 103 extends is still relatively long. After the battery cell 100 is installed in the shell 201, the isolation membrane 103 may still extend out of the shell 201, affecting the packaging welding step of the shell 201. When the heating temperature is greater than 170°C, the heating temperature is too high, and the isolation membrane 103 shrinks to a large size. Further shrinkage of the isolation membrane 103 during subsequent hot box testing may cause the first pole piece 101 and the second pole piece 102 to contact, thereby causing a short circuit, posing a safety hazard.

[0058] It should be noted that in some embodiments of the present invention, a ceramic coating is attached to the outside of the substrate of the isolation membrane 103. The thickness of the ceramic coating will also affect the heat resistance of the isolation membrane 103. The thicker the ceramic coating, the stronger the heat resistance. Preferably, the thickness of the ceramic coating is selected to be controlled between 0.5μm and 1μm.

[0059] It should be noted that, in some embodiments of the present invention, the degree of shrinkage of the isolation membrane 103 is related to multiple factors. In addition to the above-mentioned heating temperature and the size of the isolation membrane 103 extending relative to the first pole piece 101 before processing, the heating time and the distance between the heating end face and the isolation membrane 103 will affect the degree of shrinkage of the isolation membrane 103. Specifically, the heating time is preferably set to 0.5s~1s. The longer the time, the greater the degree of shrinkage of the isolation membrane 103, and the shorter the time, the smaller the degree of shrinkage of the isolation membrane 103; and the heating end face is preferably set to a distance from the outer periphery of the first pole piece 101 between 0.2mm~0.3mm, specifically, it can be 0.2mm, 0.25mm, 0.3mm and other lengths. The closer the distance, the closer the distance between the heating end face and the isolation membrane 103, the greater the degree of fit between them, and the greater the degree of shrinkage of the isolation membrane 103. The farther the distance, the smaller the degree of fit between them, and the smaller the degree of shrinkage of the isolation membrane 103. Specifically, the adjustment of these parameters is achieved by observing the state of the isolation membrane 103 during the processing. When the isolation membrane 103 reaches an ideal state, that is, the protruding size relative to the first pole piece 101 after shrinkage is within a preset range, and they are also bonded to each other, the processing is completed.

[0060] In some embodiments of the present invention, the complete process of the battery manufacturing method is as follows:

[0061] S1: forming a battery cell 100 by stacking a first electrode sheet 101, an isolation film 103 and a second electrode sheet 102 in sequence;

[0062] S2: Welding, gluing, and bending the first tab 301 and the second tab 302 at the head of the battery cell 100;

[0063] S3: heating the edge of the isolation film 103 (i.e., ironing the edge);

[0064] S4: Adhesive 109 is attached to the periphery of the battery cell 100 to secure it. Double-sided tape is also attached to the periphery of the battery cell 100 to provide a tighter connection to the housing 201 .

[0065] S5: cutting the first electrode tab 301 and the second electrode tab 302 and welding them to the housing 201;

[0066] S6: Place the battery cell 100 into the storage cavity 202 of the shell 201 and weld the shell cover.

[0067] Step S3 is the main process. Specifically, the heating time, the extension distance of the isolation film 103 relative to the first electrode, the heating temperature, and the intervals and selection methods of the parameters between the heating end surface and the isolation film 103 have been described above.

[0068] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. In addition, the embodiments of the present invention and the features of the embodiments can be combined with each other unless there is a conflict.

Claims

1. A battery, characterized in that The battery comprises a housing and a battery core, wherein the battery core is arranged inside the housing, the battery core comprises an isolation film, a plurality of first pole pieces, and a plurality of second pole pieces stacked on each other, the isolation film comprises a multi-layer separator, and the separator comprises: A main body portion is provided between adjacent first pole pieces and adjacent second pole pieces; a transition portion connected to an edge of the main body portion, wherein in the stacking direction of the first pole piece and the second pole piece, two adjacent transition portions jointly wrap at least one side edge of the second pole piece; A contraction portion is connected to an edge of a side of the transition portion away from the main body portion, and in the stacking direction of the first pole piece and the second pole piece, at least two adjacent contraction portions are connected to each other.

2. The battery according to claim 1, characterized in that The bonding force F between the two mutually connected contraction parts satisfies: 0<F<10N / mm.

3. The battery according to claim 1, characterized in that One end of the contraction portion connected to the transition portion is the inner end of the contraction portion, and the angle between the tangent of the contraction portion at the inner end and the plane where the second pole piece is located is the wrap angle, 0°<wrapping angle<90°.

4. The battery according to claim 3, characterized in that 20°≤wrapping angle≤65°.

5. The battery according to claim 1, characterized in that The battery also includes a first pole tab, which is connected to the first pole piece. The main body includes a first edge and a second edge relative to each other, and a third edge and a fourth edge relative to each other. The first pole tab protrudes relative to the fourth edge. The entire area of ​​the first edge, the second edge and the third edge is provided with the contraction portion, and at least a portion of the fourth edge is provided with the contraction portion.

6. The battery according to claim 1, characterized in that The isolation film protrudes relative to the first pole piece along the length direction of the battery cell by a dimension L1, where 0.1 mm ≤ L1 < 3 mm.

7. The battery according to claim 1, characterized in that The isolation film protrudes relative to the first pole piece by a dimension L2 along the width direction of the battery cell, and 0.1 mm ≤ L2 < 1 mm.

8. The battery according to claim 7, characterized in that The corners of the isolation membrane and the first pole piece are both rounded, the radius of the rounded corner of the isolation membrane is R1, the radius of the rounded corner of the first pole piece is R2, and R1≤R2+L2.

9. The battery according to claim 1, characterized in that Along the width direction of the battery core, the distance between the inner wall of the shell and the outer edge of the corresponding isolation membrane is L3, and L3≥0.

10. The battery according to claim 9, characterized in that The distance between the inner wall of the shell and the outer edge of the corresponding first pole piece is L4, 0mm<L3<(L4-0.1)mm.

Images