Battery cell, battery, battery module, battery pack, and electronic product

Abstract

Provided in the present application is a battery cell, comprising: at least one first electrode sheet, at least one second electrode sheet and at least one separator, which are stacked, wherein adjacent first and second electrode sheets have opposite polarities, and the adjacent first and second electrode sheets are separated from each other by means of the separator. The separator has a main area and a first area located on at least one side of the main area, wherein the refractive index of a separator substrate in the first area is less than that of a separator substrate in the main area. By means of the embodiments of the present application, the energy conversion efficiency of the edge of the separator can be improved, and the degree of thermal shrinkage of the separator is reduced, thereby improving the safety performance of a battery.

Description

Battery cells, batteries, battery modules, battery packs and electronic products Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell.

[0002] Background of the Invention

[0003] Lithium-ion batteries are widely used in consumer electronics, new energy vehicles, and energy storage power stations due to their high specific energy, low discharge, and excellent cycle performance. With the deepening implementation of the "dual carbon" initiative, lithium-ion batteries are experiencing strong development momentum, gradually moving towards fast charging, long life, high energy density, and high safety.

[0004] During the high-rate charge and discharge process of the stacked battery cell, the heat generated by the electrodes will be transferred to the diaphragm, causing the heat to accumulate in the diaphragm and resulting in thermal contraction at the edge of the diaphragm, causing the positive and negative electrodes at the edge to contact and thus short-circuit.

[0005] Summary of the Invention

[0006] In view of this, the present application provides a battery cell that solves the problem in the related art that the diaphragm of the laminated battery cell shrinks at the edge of the diaphragm due to heat accumulation, resulting in a short circuit of the positive electrode.

[0007] As a first aspect of the present application, the present application provides a battery cell comprising: at least one first electrode piece, at least one second electrode piece and at least one diaphragm arranged in a stacked manner, wherein the polarities of adjacent first electrode pieces and second electrode pieces are opposite, and adjacent first electrode pieces and second electrode pieces are separated by the diaphragm; wherein the diaphragm has a main body region and a first region located on at least one side of the main body region, wherein the refractive index of the diaphragm substrate of the first region is less than the refractive index of the diaphragm substrate of the main body region.

[0008] In one embodiment of the present application, at least one diaphragm includes multiple diaphragms, and in the stacking direction, the multiple diaphragms are divided into a first diaphragm area, a second diaphragm area and a third diaphragm area, wherein the third diaphragm area is located between the first diaphragm area and the second diaphragm area; wherein the average width of the first area of ​​the diaphragm in the first diaphragm area is less than or equal to the average width of the first area of ​​the diaphragm in the third diaphragm area; and / or the average width of the first area of ​​the diaphragm in the second diaphragm area is less than or equal to the average width of the first area of ​​the diaphragm in the third diaphragm area.

[0009] In one embodiment of the present application, the maximum value of the width of the first area in the first diaphragm area is less than or equal to the minimum value of the width of the first area of ​​the diaphragm in the third diaphragm area; and / or the maximum value of the width of the first area of ​​the diaphragm in the second diaphragm area is less than or equal to the minimum value of the width of the first area of ​​the diaphragm in the third diaphragm area.

[0010] In one embodiment of the present application, the width of the first area of ​​the diaphragm in the first diaphragm area is 1 / 10 to 1 / 2 of the width of the first area of ​​the diaphragm in the third diaphragm area; and / or the width of the first area of ​​the diaphragm in the second diaphragm area is 1 / 10 to 1 / 2 of the width of the first area of ​​the diaphragm in the third diaphragm area.

[0011] In one embodiment of the present application, the width of the first area of ​​the diaphragm in the first diaphragm area increases gradually in a first direction from away from the third diaphragm area to close to the third diaphragm area; and / or the width of the first area of ​​the diaphragm in the second diaphragm area increases gradually in a second direction from away from the third diaphragm area to close to the third diaphragm area.

[0012] In one embodiment of the present application, the absolute value of the difference between the widths of the first regions of two adjacent diaphragms in at least one diaphragm is between 0.010 mm and 1 mm.

[0013] In one embodiment of the present application, in the third direction from the first diaphragm region to the second diaphragm region, the width of the first region of the diaphragm in the third diaphragm region first increases and then decreases.

[0014] In one embodiment of the present application, the length of the diaphragm in the first diaphragm area is equal to 1 to 1.5 times the length of the diaphragm in the third diaphragm area; and / or the length of the diaphragm in the second diaphragm area is equal to 1 to 1.5 times the length of the diaphragm in the third diaphragm area.

[0015] In one embodiment of the present application, the length of the diaphragm in the first diaphragm area decreases in a first direction from away from the third diaphragm area to close to the third diaphragm area; and / or the length of the diaphragm in the second diaphragm area decreases in a second direction from away from the third diaphragm area to close to the third diaphragm area.

[0016] In one embodiment of the present application, in the third direction from the first diaphragm region to the second diaphragm region, the length of the diaphragm in the third diaphragm region first decreases and then increases.

[0017] In one embodiment of the present application, the spacing between the boundary of the diaphragm in the first diaphragm region and the boundary of the adjacent first pole piece is 1 / 5 to 1 / 2 of the spacing between the boundary of the diaphragm in the third diaphragm region and the boundary of the adjacent first pole piece; and / or the spacing between the boundary of the diaphragm in the second diaphragm region and the boundary of the adjacent first pole piece is 1 / 5 to 1 / 2 of the spacing between the boundary of the diaphragm in the third diaphragm region and the boundary of the adjacent first pole piece.

[0018] In one embodiment of the present application, the distance between the boundary of the diaphragm in the first diaphragm region and the boundary of the adjacent first pole piece decreases in a first direction away from the third diaphragm region to close to the third diaphragm region; and / or the distance between the boundary of the diaphragm in the second diaphragm region and the boundary of the adjacent first pole piece decreases in a second direction away from the third diaphragm region to close to the third diaphragm region.

[0019] In one embodiment of the present application, at least one diaphragm includes a plurality of diaphragms, one ends of at least two of the plurality of diaphragms are gathered at one side of the battery cell; and one ends of at least two diaphragms are bonded.

[0020] In one embodiment of the present application, one ends of the plurality of separators are gathered at a middle portion of one side of the battery cell.

[0021] In one embodiment of the present application, the refractive index of the diaphragm substrate in the main region is 1.49-1.60, and / or the refractive index of the diaphragm substrate in the first region is less than or equal to 1.40.

[0022] In one embodiment of the present application, the hardness of the first region is greater than the hardness of the main region.

[0023] The present application provides a battery cell, in which a diaphragm has a main region and a first region located on at least one side of the main region, wherein the refractive index of the diaphragm substrate in the first region is lower than the refractive index of the diaphragm substrate in the main region. The higher refractive index of the diaphragm substrate can improve the energy conversion efficiency of the edge of the diaphragm, and can also reduce heat accumulation under light, reduce the temperature rise at the edge of the diaphragm, thereby avoiding heat accumulation of the diaphragm during charging and discharging, reducing the degree of thermal shrinkage of the diaphragm, and thus improving the safety performance of the battery.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features, and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0026] FIG1 is a schematic structural diagram of a battery cell provided in one embodiment of the present application.

[0027] FIG2 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0028] FIG3 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0029] FIG4 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0030] FIG5 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0031] FIG6 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0032] FIG7 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0033] FIG8 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0034] FIG9 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0035] FIG10 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0036] FIG11 is a schematic structural diagram of a battery cell provided in another embodiment of the present application.

[0037] Reference numerals: 10 - first pole piece, 11 - second pole piece, 12 - diaphragm, 121 - second region, 122 - first region, 123 - main body region, Q1 - first diaphragm region, Q2 - second diaphragm region, Q3 - third diaphragm region.

[0038] Modes for Carrying Out the Invention

[0039] In the description of the application, the meaning of "multiple" is at least two, for example two, three, etc., unless otherwise clearly and specifically limited. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back, top, bottom ...) are only used to explain the relative position relationship, motion situation, etc. between each component under a certain specific posture (as shown in the drawings). If this specific posture changes, this directional indication also changes accordingly. In addition, the terms "comprise" and "have" and any deformation thereof are intended to cover non-exclusive inclusion. For example, the process, method, system, product or equipment comprising a series of steps or units is not limited to the steps or units listed, but optionally also includes the steps or units not listed, or optionally also includes other steps or units inherent to these processes, methods, products or equipment.

[0040] In addition, references to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] During the production of stacked cells, the diaphragm may exceed the electrode too much (greater than the design requirements). If it is directly packaged or assembled into a shell, the excess diaphragm may affect the packaging of the aluminum-plastic film or the welding of the shell, so it is often necessary to cut the excess diaphragm. In the production of battery cells, the diaphragm is traditionally cut with a cutter. The cutting effect at the diaphragm incision is poor, and it is easy to burr or curl. The burr of the electrode can easily pass through the burr or curl of the diaphragm and contact the other electrode, causing a short circuit between the positive and negative electrodes. In addition, during the drop test of the stacked cell, the diaphragm layer in the middle is easily stressed and ruptured, resulting in a short circuit. Furthermore, during the high-rate charge and discharge process of the stacked cell, the heat generated by the electrode will be transferred to the diaphragm, causing the heat of the diaphragm to accumulate, resulting in thermal shrinkage at the edge of the diaphragm, causing the positive and negative electrodes at the edge to contact and short circuit.

[0042] To solve the above problems, an embodiment of the present application provides a battery cell.

[0043] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical methods in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0044] As a first aspect of the present application, as shown in Figures 1-10, the present application provides a battery cell, as shown in Figures 1-10, the battery cell comprises: at least one first electrode sheet 10, at least one second electrode sheet 11 and at least one diaphragm 12 stacked together, the polarities of adjacent first electrode sheets 10 and second electrode sheets 11 are opposite, and the adjacent first electrode sheets 10 and second electrode sheets 11 are separated by the diaphragm 12; specifically, the first electrode sheet 10 is a positive electrode sheet and the second electrode sheet 11 is a negative electrode sheet; or the first electrode sheet 10 is a negative electrode sheet and the second electrode sheet 11 is a positive electrode sheet, as long as the polarities of the first electrode sheet 10 and the second electrode sheet 11 are opposite.

[0045] The diaphragm 12 has a main body region, a first region 122 located on at least one side of the main body region, and a second region 121 located on a side of the first region away from the main body region. Optionally, a width of the first region 122 is less than 200 μm.

[0046] In one embodiment, the separator 12 includes a substrate layer, a ceramic layer, and a glue layer disposed on the substrate layer. In one example, the ceramic layer of the separator is disposed opposite the positive electrode active material layer of the positive electrode sheet, and the glue layer of the separator is disposed opposite the negative electrode active material layer of the negative electrode sheet.

[0047] The diaphragm located between the first pole piece and the second pole piece in the battery cell has a main body region and a first region located on at least one side of the main body region. The refractive index of the diaphragm substrate in the first region is smaller than the refractive index of the diaphragm substrate in the main body region.

[0048] The refractive index of the substrate of the diaphragm in the lithium-ion battery is used to characterize the transparency of the diaphragm. The transparency of the diaphragm refers to the degree of light transmittance of the diaphragm, that is, the ability of light to propagate in the diaphragm. The transparency of the diaphragm has an important impact on the charge and discharge efficiency and safety of the lithium-ion battery. The main area has a higher refractive index of the diaphragm substrate, which can prevent the edge temperature of the diaphragm from rising too high. Furthermore, the higher refractive index of the diaphragm substrate in the first area can improve the energy conversion efficiency of the edge of the diaphragm, and at the same time can reduce heat accumulation under light, reduce the temperature increase at the edge of the diaphragm, thereby avoiding heat accumulation of the diaphragm during the charge and discharge process, and reduce the degree of thermal shrinkage of the diaphragm, thereby improving the safety performance of the battery.

[0049] In some examples, laser cutting can be used to remove excess diaphragm. The heat accumulation of laser energy can melt or even vaporize the material in a relatively short period of time. After laser cutting, a heat-affected zone (HAZ), a carbonized zone (CAZ), and a non-HAZ (NHAZ) can be formed on the remaining diaphragm. For example, the first zone can be the HAZ, the second zone can be the CAZ, and the main zone can be the NHAZ.

[0050] Optionally, the hardness of the first region 122 of the diaphragm 12 is greater than the hardness of the main region 123 of the diaphragm. Therefore, the first region 122 located at the edge of the diaphragm 12 has a stronger ability to resist burr penetration than the main region 123, thereby reducing the probability of burrs on the pole piece passing through the edge of the diaphragm 12 and causing a short circuit.

[0051] In one embodiment of the present application, the plurality of diaphragms 12 are divided into a first diaphragm region Q1, a second diaphragm region Q2, and a third diaphragm region Q3 in the stacking direction, wherein the third diaphragm region Q3 is located between the first diaphragm region Q1 and the second diaphragm region Q2. The average width of the first regions 122 of the diaphragms in the first diaphragm region Q1 is less than or equal to the average width of the first regions 122 of the diaphragms in the third diaphragm region Q3. For example, the first diaphragm region Q1 includes three diaphragms, and the widths of the first regions of the three diaphragms are d11, d12, and d13, respectively. The third diaphragm region Q3 includes four diaphragms, and the widths of the first regions of the four diaphragms are d31, d32, d33, and d34, respectively. Then, (d11+d12+d13) / 3 ≤ (d31+d32+d33+d34) / 4. And / or the average width of the first area 122 of the diaphragm in the second diaphragm area Q2 is less than or equal to the average width of the first area 122 of the diaphragm in the third diaphragm area Q3. For example, the second diaphragm area Q2 includes two diaphragms, and the widths of the first areas of the two diaphragms are d21 and d22 respectively. The third diaphragm area Q3 includes three diaphragms, and the widths of the first areas of the three diaphragms are d31, d32, and d33 respectively. Then (d21+d22) / 2≤(d31+d32+d33) / 3.

[0052] In one embodiment of the present application, the plurality of diaphragms 12 are divided into a first diaphragm region Q1, a second diaphragm region Q2, and a third diaphragm region Q3 in the stacking direction, wherein the third diaphragm region Q3 is located between the first diaphragm region Q1 and the second diaphragm region Q2. The maximum width of the first region 122 of the diaphragms in the first diaphragm region Q1 is less than or equal to the minimum width of the first region 122 of the diaphragms in the third diaphragm region Q3. For example, the first diaphragm region Q1 includes three diaphragms, and the widths of the first regions of the three diaphragms are d11, d12, and d13, respectively, where d11 < d12 < d13. The third diaphragm region Q3 includes four diaphragms, and the widths of the first regions of the four diaphragms are d31, d32, d33, and d34, respectively, where d31 < d32 = d33 < d34, and thus d13 ≤ d31. And / or the maximum value of the width of the first area 122 of the diaphragm in the second diaphragm area Q2 is less than or equal to the minimum value of the width of the first area 122 of the diaphragm in the third diaphragm area Q3. For example, the second diaphragm area Q2 includes two diaphragms, and the widths of the first areas of the two diaphragms are d21 and d22, respectively, wherein d21<d22; the third diaphragm area Q3 includes three diaphragms, and the widths of the first areas of the three diaphragms are d31, d32, and d33, respectively, wherein d31<d32<d33, then d22≤d31.

[0053] Optionally, the number of diaphragms in the third diaphragm area Q3 is greater than the number of diaphragms in the first diaphragm area Q1, and the number of diaphragms in the third diaphragm area Q3 is greater than the number of diaphragms in the second diaphragm area Q2, that is, the number of diaphragms in the middle area of ​​the chip structure is greater than the number of diaphragms in the two side areas, thereby playing a supporting role, preventing the diaphragms in the middle area from being more easily broken due to extrusion, and preventing burrs on the pole piece from passing through the diaphragm.

[0054] Optionally, the number of diaphragms in the first diaphragm region Q1 may be the same as the number of diaphragms in the second diaphragm region Q2 , that is, the diaphragms on both sides of the chip structure in the third diaphragm region Q3 are evenly distributed in number.

[0055] Optionally, the number of diaphragms in the first diaphragm region Q1 may be different from the number of diaphragms in the second diaphragm region Q2.

[0056] The battery cell provided in the present application divides the diaphragm 12 in the battery cell into three diaphragm 12 areas. The maximum width of the first diaphragm area Q1 located on both sides of the third diaphragm area Q3 and the first area 122 of the diaphragm 12 in the second diaphragm area Q2 is less than or equal to the minimum width of the first area 122 of the diaphragm 12 in the third diaphragm area Q3. This can prevent the diaphragm 12 in the middle area from being more easily broken due to the extrusion effect and prevent the burrs on the pole piece from passing through the diaphragm 12, thereby further reducing the probability of short circuit in the battery cell, improving the pressure interference resistance of the diaphragm 12 in the third diaphragm area Q3, and improving the safety performance of the battery cell. At the same time, the refractive index of the diaphragm substrate in the first area 122 is less than the refractive index of the diaphragm substrate in the main area 123. Specifically, the refractive index of the diaphragm substrate in the main area 123 is 1.49 to 1.60, and the refractive index of the diaphragm substrate in the first area 122 is less than or equal to 1.40. It should be noted that in addition to the different refractive indices of the membrane substrates, the first region 122 and the main region 123 also differ in the following: after baking at 90°C for 24 hours, the membrane in the main region 123 has a transverse shrinkage of approximately 1% and a longitudinal shrinkage of 3%-7%. After baking at 90°C for 24 hours, the membrane in the first region 122 has a transverse and longitudinal shrinkage close to zero.

[0057] Optionally, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 is 1 / 10 to 1 / 2 of the width of the first region 122 of the diaphragm in the third diaphragm region Q3, so that the first region 122 of the diaphragm 12 with the smallest width in the first diaphragm region Q1 will not exceed the lower limit of the control range of the spacing between the boundary of the diaphragm 12 and the boundary of the adjacent first electrode piece, nor will it exceed the lower limit of the control range of the spacing between the boundary of the diaphragm 12 and the boundary of the adjacent second electrode piece, so as to reduce the probability of poor coverage of the diaphragm 12.

[0058] Similarly, the width of the first region 122 of the diaphragm in the second diaphragm region Q2 is 1 / 10 to 1 / 2 of the width of the first region 122 of the diaphragm in the third diaphragm region Q3. The first region 122 of the diaphragm 12 with the smallest width in the second diaphragm region Q2 will not exceed the lower limit of the control range of the distance between the boundary of the diaphragm 12 and the boundary of the adjacent first electrode piece, nor will it exceed the lower limit of the control range of the distance between the boundary of the diaphragm 12 and the boundary of the adjacent second electrode piece, so as to reduce the probability of poor coverage of the diaphragm 12.

[0059] Optionally, the distribution of the width of the first region 122 of the diaphragm in the first diaphragm region Q1 can be as follows: as shown in Figure 2, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 increases in the first direction from away from the third diaphragm region Q3 to close to the third diaphragm region Q3, that is, the closer to the third diaphragm region Q3, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 gradually increases.

[0060] Optionally, the distribution of the width of the first region 122 of the diaphragm in the second diaphragm region Q2 can be as follows: as shown in Figure 3, the width of the first region 122 of the diaphragm in the second diaphragm region Q2 increases in the second direction from away from the third diaphragm region Q3 to close to the third diaphragm region Q3, that is, the closer to the third diaphragm region Q3, the more gradually the width of the first region 122 of the diaphragm in the second diaphragm region Q2 increases.

[0061] Optionally, the width of the first region 122 of the diaphragms in the third diaphragm region Q3 is distributed as follows: As shown in FIG1 , in the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the width of the first region 122 of the diaphragms in the third diaphragm region Q3 first decreases and then increases. That is, when the third diaphragm region Q3 includes three or more diaphragms, the width of the first region 122 of the diaphragms in the third diaphragm region Q3 first increases and then decreases.

[0062] It should be noted that, in the same battery cell, the distribution form of the width of the first region 122 of the diaphragm in the first diaphragm region Q1, the distribution form of the width of the first region 122 of the diaphragm in the second diaphragm region Q2, and the distribution form of the width of the first region 122 of the diaphragm in the third diaphragm region Q3 can be satisfied at the same time, or one or two of them can be satisfied, for example:

[0063] As shown in Figures 1, 3, 5 and 6, in the first direction from away from the third diaphragm area Q3 to close to the third diaphragm area Q3 (it should be explained that the first direction is from the first diaphragm area Q1 to the third diaphragm area Q3), the width of the first area 122 of the diaphragm in the first diaphragm area Q1 increases, that is, the closer to the third diaphragm area Q3, the width of the first area 122 of the diaphragm in the first diaphragm area Q1 gradually increases; and in the second direction from away from the third diaphragm area Q3 to close to the third diaphragm area Q3 (it should be explained that the second direction is from the second diaphragm area Q2 to the third diaphragm area Q3), the width of the first area 122 of the diaphragm in the second diaphragm area Q2 increases, that is, the closer to the third diaphragm area Q3, the width of the first area of ​​the diaphragm in the second diaphragm area Q2 increases. In the third direction from the first diaphragm area Q1 to the second diaphragm area Q2 (it should be explained that the third direction starts from the first diaphragm area Q1 and points to the second diaphragm area Q2. Since the second diaphragm area Q2 is located on the other side of the third diaphragm area Q3, the first direction and the third direction have the same direction, and the third direction can be considered to be the same as the first direction), the width of the first area 122 of the diaphragm in the third diaphragm area Q3 first increases and then decreases.

[0064] As shown in Figure 2, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 gradually increases as it approaches the third diaphragm region Q3. In the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the width of the first region 122 of the diaphragm in the third diaphragm region Q3 first increases and then decreases. Although the width of the first region 122 of the diaphragm in the first diaphragm region Q1 is smaller than the width of the first region 122 of the diaphragm in the third diaphragm region Q3, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 increases in the first direction. Furthermore, the width of the first region 122 of the diaphragm in the second diaphragm region Q2 gradually decreases in the second direction.

[0065] As shown in Figure 4 , the width of the first region 122 of the diaphragm in the second diaphragm region Q2 gradually increases as the diaphragm approaches the third diaphragm region Q3. In the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the width of the first region 122 of the diaphragm in the third diaphragm region Q3 first increases and then decreases. Although the width of the first region 122 of the diaphragm in the second diaphragm region Q2 is always smaller than the width of the first region 122 of the diaphragm in the third diaphragm region Q3, the width of the first region 122 of the diaphragm in the second diaphragm region Q2 decreases in the third direction. Furthermore, in the first direction, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 gradually decreases.

[0066] Optionally, when the distribution form of the width of the first region 122 of the diaphragm in the first diaphragm region Q1, the distribution form of the width of the first region 122 of the diaphragm in the second diaphragm region Q2, and the distribution form of the width of the first region 122 of the diaphragm in the third diaphragm region Q3 described above are all satisfied by the diaphragms in the same battery cell, that is, the width of the first region 122 of the diaphragm in the first diaphragm region Q1 increases in the first direction from away from the third diaphragm region Q3 to close to the third diaphragm region Q3; the width of the first region 122 of the diaphragm in the second diaphragm region Q2 increases in the second direction from away from the third diaphragm region Q3 to close to the third diaphragm region Q3; in the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the width of the first region 122 in the third diaphragm region Q3 first increases and then decreases, as shown in Figures 1, 3, 5 and 6. The width distribution of a group of diaphragms symmetrical about the third diaphragm region Q3 (one diaphragm in a group of diaphragms is located in the first diaphragm region Q1 and the other diaphragm is located in the second diaphragm region Q2) is as follows:

[0067] (1) As shown in FIG3 , the widths of the first regions 122 in any group of diaphragms symmetrical about the third diaphragm region Q3 (one diaphragm in a group is located in the first diaphragm region Q1 and the other diaphragm is located in the second diaphragm region Q2) are all different.

[0068] (2) As shown in FIG5 , the width of the first region 122 in one group of diaphragms in the plurality of symmetrical groups of diaphragms about the third diaphragm region Q3 (one diaphragm in a group of diaphragms is located in the first diaphragm region Q1 and the other diaphragm is located in the second diaphragm region Q2 ) is the same.

[0069] (3) As shown in FIG6 , the width of the first region 122 in any group of diaphragms among the plurality of diaphragm groups symmetrical about the third diaphragm region Q3 (one diaphragm in a group is located in the first diaphragm region Q1 and the other diaphragm is located in the second diaphragm region Q2) is the same.

[0070] Optionally, the absolute value of the difference in width between the first areas 122 of two adjacent diaphragms 12 is between 0.010 mm and 1 mm, so that the first area 122 of the diaphragm 12 with the smallest first area 122 will not exceed the lower limit of the control range of the distance between the boundary of the diaphragm 12 and the boundary of the adjacent first pole piece, nor will it exceed the lower limit of the control range of the distance between the boundary of the diaphragm 12 and the boundary of the adjacent second pole piece, so as to reduce the probability of poor coverage of the diaphragm 12.

[0071] In another embodiment of the present application, as shown in Figures 7, 8 and 9, the length of the diaphragm in the first diaphragm area Q1 is equal to 1 to 1.5 times the length of the diaphragm in the third diaphragm area Q3, that is, l1 = 1 to 1.5l3; and / or the length of the diaphragm in the second diaphragm area Q2 is equal to 1 to 1.5 times the length of the diaphragm in the third diaphragm area Q3, that is, l2 = 1 to 1.5l3.

[0072] Specifically, the length of any one diaphragm in the first diaphragm region Q1 only needs to be 1 to 1.5 times the length of any one diaphragm in the third diaphragm region Q3 .

[0073] For example, if the first diaphragm region Q1 includes two diaphragms and the third diaphragm region Q3 includes three diaphragms, the length of one diaphragm in the first diaphragm region Q1 only needs to be 1 to 1.5 times the length of one diaphragm in the third diaphragm region Q3. The lengths of the diaphragms in the first diaphragm region Q1 can be the same or different.

[0074] Similarly, the length of any one diaphragm in the second diaphragm region Q2 only needs to be 1 to 1.5 times the length of any one diaphragm in the third diaphragm region Q3 .

[0075] For example, if the second diaphragm region Q2 includes two diaphragms and the third diaphragm region Q3 includes three diaphragms, the length of the diaphragms in the second diaphragm region Q2 only needs to be 1 to 1.5 times the length of one of the diaphragms in the third diaphragm region Q3. The lengths of the diaphragms in the second diaphragm region Q2 can be the same or different.

[0076] The battery cell provided in the present application has a diaphragm 12 in the third diaphragm area Q3, a diaphragm in the second diaphragm area Q2, and a diaphragm 12 in the first diaphragm area Q1 of different lengths, and the diaphragms 12 on both sides are longer, while the diaphragm 12 in the middle is shorter, so that all the diaphragms 12 can be gathered on one side of the battery cell to form a coating structure, thereby increasing the battery's ability to resist falling and improving battery safety.

[0077] Optionally, the length distribution of the diaphragms in the first diaphragm region Q1 is as follows:

[0078] As shown in FIG7 , the length of the diaphragm in the first diaphragm region Q1 decreases in a first direction from away from the third diaphragm region Q3 to close to the third diaphragm region Q3 ; that is, the closer to the third diaphragm region Q3 , the shorter the length of the diaphragm.

[0079] Optionally, as shown in FIG8 , the length distribution of the diaphragms in the second diaphragm region Q2 is as follows:

[0080] The length of the diaphragm in the second diaphragm region Q2 decreases gradually from being away from the third diaphragm region Q3 to being close to the third diaphragm region Q3 , that is, the closer to the third diaphragm region Q3 , the shorter the length of the diaphragm.

[0081] Optionally, as shown in FIG7 , the lengths of the third diaphragms within the third diaphragm region Q3 are distributed as follows: in the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the lengths of the diaphragms in the third diaphragm region Q3 first decrease and then increase. For example, when the third diaphragm region Q3 includes three or more diaphragms, the lengths of the diaphragms in the third diaphragm region Q3 first decrease and then increase. If the third diaphragm region Q3 includes an odd number of diaphragms, the length of the diaphragm located in the center of the third diaphragm region Q3 is the smallest. Then, starting from this center diaphragm, the lengths of the diaphragms increase in the direction toward the first diaphragm region Q1. Similarly, starting from this center diaphragm, the lengths of the diaphragms increase in the direction toward the second diaphragm region Q2.

[0082] It should be noted that the length distribution form of the diaphragm in the first diaphragm region Q1, the length distribution form of the diaphragm in the second diaphragm region Q2, and the length distribution form of the diaphragm in the third diaphragm region Q3 described above can be satisfied at the same time in the same battery cell, or one or two of them can be satisfied, for example:

[0083] As shown in Figure 7, in the first direction from away from the third diaphragm region Q3 to closer to it, the length of the diaphragms in the first diaphragm region Q1 decreases, i.e., the closer to the third diaphragm region Q3, the gradually decreasing length of the diaphragms in the first diaphragm region Q1. Furthermore, in the second direction from away from the third diaphragm region Q3 to closer to it, the length of the diaphragms in the second diaphragm region Q2 decreases, i.e., the closer to the third diaphragm region Q3, the gradually decreasing length of the diaphragms in the second diaphragm region Q2. In the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the length of the diaphragms in the third diaphragm region Q3 first decreases and then increases. That is, in the entire cell, the length of the diaphragm 12 located in the center is the smallest, and then increases towards the sides.

[0084] Optionally, as shown in FIG10 , the leftmost side of all the diaphragms 12 in the entire battery cell may form a first concentric arc, and the rightmost side of all the diaphragms 12 in the entire battery cell may form a second concentric arc. The diameter of the first concentric arc may be the same as or different from the diameter of the second concentric arc. All the diaphragms 12 may be gathered at the center of one side of the battery cell, that is, the two sides of the coating structure are brought closer to the middle, forming a multi-layer composite bonding layer as a whole. The bonding layer has a certain bonding strength, and the single-layer bonding strength is ≥0.002N / mm. The electrode can be fixed and wrapped during the falling process of the battery cell to prevent the electrode from falling out, thereby improving the falling performance and safety performance of the battery cell.

[0085] As shown in Figure 8 , the length of the diaphragms in the second diaphragm region Q2 decreases as the diaphragms approach the third diaphragm region Q3. In the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the length of the diaphragms in the third diaphragm region Q3 first decreases and then increases. Although the length of the diaphragms in the first diaphragm region Q1 is 1 to 1.5 times that of the diaphragms in the third diaphragm region Q3, the lengths of the diaphragms in the first diaphragm region Q1 do not increase or decrease in a stepwise manner.

[0086] As shown in Figure 9 , the lengths of the diaphragms in the first diaphragm region Q1 decrease as they approach the third diaphragm region Q3. In the third direction from the first diaphragm region Q1 to the second diaphragm region Q2, the lengths of the diaphragms in the third diaphragm region Q3 first decrease and then increase. Although the lengths of the diaphragms in the second diaphragm region Q2 are 1 to 1.5 times the lengths of the diaphragms in the third diaphragm region Q3, the lengths of the diaphragms in the second diaphragm region Q2 do not increase or decrease in a stepwise manner.

[0087] In another embodiment of the present application, the distance between the boundary of the diaphragm in the first diaphragm region Q1 and the boundary of the adjacent first electrode piece is 1 / 5 to 1 / 2 of the distance between the boundary of the diaphragm in the third diaphragm region Q3 and the boundary of the adjacent first electrode piece; and / or

[0088] The distance between the boundary of the diaphragm in the second diaphragm region Q2 and the boundary of the adjacent first pole piece is 1 / 5 to 1 / 2 of the distance between the boundary of the diaphragm in the third diaphragm region Q3 and the boundary of the adjacent first pole piece.

[0089] Specifically, the distance between the boundary of any diaphragm in the first diaphragm region Q1 and the boundary of the adjacent first electrode piece is equal to 1 / 5 to 1 / 2 of the distance between the boundary of one diaphragm in the third diaphragm region Q3 and the boundary of the adjacent first electrode piece.

[0090] For example, if the first diaphragm region Q1 includes two diaphragms and the third diaphragm region Q3 includes three diaphragms, then the spacing between the boundary of a diaphragm in the first diaphragm region Q1 and the boundary of the adjacent first electrode piece only needs to be equal to the spacing between the boundary of a diaphragm in the third diaphragm region Q3 and the boundary of the adjacent first electrode piece. The spacing between the boundary of a diaphragm in the same first diaphragm region Q1 and the boundary of the adjacent first electrode piece can be the same or different.

[0091] Similarly, the distance between the boundary of any diaphragm in the second diaphragm region Q2 and the boundary of the adjacent first electrode piece is equal to 1 / 5 to 1 / 2 of the distance between the boundary of one diaphragm in the third diaphragm region Q3 and the boundary of the adjacent first electrode piece.

[0092] For example, if the second diaphragm region Q2 includes two diaphragms and the third diaphragm region Q3 includes three diaphragms, then the spacing between the boundary of a diaphragm in the second diaphragm region Q2 and the boundary of the adjacent first electrode piece only needs to be equal to the spacing between the boundary of a diaphragm in the third diaphragm region Q3 and the boundary of the adjacent first electrode piece. The spacing between the boundary of the diaphragm in the same second diaphragm region Q2 and the boundary of the adjacent first electrode piece can be the same or different.

[0093] Optionally, the spacing between the boundary of the diaphragm in the first diaphragm region Q1 and the boundary of the adjacent first pole piece is distributed as follows:

[0094] In the first direction from away from the third diaphragm region Q3 to close to the third diaphragm region Q3, the distance between the boundary of the diaphragm in the first diaphragm region Q1 and the boundary of the adjacent first pole piece decreases; that is, the closer to the third diaphragm region Q3, the smaller the distance between the boundary of the diaphragm and the boundary of the adjacent first pole piece.

[0095] Optionally, the spacing between the boundary of the diaphragm in the second diaphragm region Q2 and the boundary of the adjacent first pole piece is distributed as follows:

[0096] In the second direction from away from the third diaphragm region Q3 to closer to the third diaphragm region Q3, the distance between the boundary of the diaphragm in the second diaphragm region Q2 and the boundary of the adjacent first electrode piece decreases. That is, the closer to the third diaphragm region Q3, the smaller the distance between the boundary of the diaphragm and the boundary of the adjacent first electrode piece.

[0097] It should be noted that in the same battery cell, the above-mentioned spacing distribution form between the boundary of the diaphragm in the first diaphragm area Q1 and the boundary of the adjacent first pole piece, and the spacing distribution form between the boundary of the diaphragm in the second diaphragm area Q2 and the boundary of the adjacent first pole piece can be satisfied at the same time, or one of them can be satisfied.

[0098] Optionally, the difference in spacing between the boundaries of two adjacent diaphragms 12 and the boundaries of the adjacent first pole pieces is less than 1 / 10 of the maximum difference in distance between the boundaries of the diaphragms 12 and the boundaries of the first pole pieces in the entire battery cell. This can improve the alignment of the entire battery cell and ensure the size capacity of the battery cell.

[0099] In another embodiment of the present application, as shown in FIG11 , in a battery cell, one end of at least two separators 12 converge on one side of the battery cell, and one end of the at least two separators is bonded together. The convergence of the at least two separators 12 at one end forms a covering structure for the battery cell, increasing the battery cell's drop resistance and improving the safety of the battery cell.

[0100] Optionally, as shown in FIG11 , when the length distribution of the diaphragm 12 in the battery cell is as shown in FIG10 , that is, the length of the middle diaphragm 12 in the battery cell is the shortest, and the lengths of the diaphragms 12 on both sides gradually increase, one end of all diaphragms 12 are gathered at the center position of one side of the battery cell (that is, the position corresponding to the middle diaphragm 12 of the battery cell), and the other end of all diaphragms 12 are gathered at the middle part of the other side of the battery cell (that is, the position corresponding to the middle diaphragm 12 of the battery cell). All diaphragms 12 can be gathered in the middle part of one side of the battery cell, that is, the two sides of the coating structure are brought closer to the middle, forming a multi-layer composite bonding layer as a whole. The bonding layer has a certain bonding strength, and the single-layer bonding strength is ≥0.002N / mm. The electrode can be fixed and wrapped during the falling process of the battery cell to prevent the electrode from falling out, thereby improving the falling performance and safety performance of the battery cell.

[0101] As a second aspect of this application, this application further provides a battery comprising a housing; and the aforementioned battery cell, the battery cell being disposed within the housing. Since the battery comprises the aforementioned battery cell and the battery has the technical features of the aforementioned battery cell, the technical effects of the battery are the same as the beneficial effects of the aforementioned battery cell, and are not further elaborated here.

[0102] As the third aspect of the present application, the present application also provides a battery module including a plurality of the above-mentioned batteries and having the technical effects of the above-mentioned batteries, which will not be elaborated here.

[0103] As a fourth aspect of the present application, the present application also provides a battery pack comprising a plurality of the battery modules described above.

[0104] As a fifth aspect of the present application, the present application further provides an electronic product, comprising the battery described above, wherein the battery provides electrical energy for the electronic product.

[0105] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0106] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0107] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent modes of the present application.

[0108] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features of the present application.

[0109] The above description is only a preferred embodiment of the invention of this application and is not intended to limit the invention of this application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention of this application should be included in the scope of protection of the invention of this application.

Claims

1. A battery cell, characterized in that: include: At least one first pole piece, at least one second pole piece and at least one diaphragm are stacked, the adjacent first pole pieces and the second pole pieces have opposite polarities, and the adjacent first pole pieces and the second pole pieces are separated by the diaphragm; The diaphragm has a main body region and a first region located at at least one side of the main body region, wherein the refractive index of the diaphragm substrate of the first region is smaller than the refractive index of the diaphragm substrate of the main body region.

2. The battery cell according to claim 1, characterized in that: The at least one diaphragm includes a plurality of diaphragms, and in the stacking direction, the plurality of diaphragms are divided into a first diaphragm region, a second diaphragm region, and a third diaphragm region, wherein the third diaphragm region is located between the first diaphragm region and the second diaphragm region; wherein an average width of the first region of the diaphragm in the first diaphragm region is less than or equal to an average width of the first region of the diaphragm in the third diaphragm region; and / or An average width of the first region of the diaphragm in the second diaphragm region is smaller than or equal to an average width of the first region of the diaphragm in the third diaphragm region.

3. The battery cell according to claim 2, characterized in that: The maximum value of the width of the first region in the first diaphragm region is less than or equal to the minimum value of the width of the first region of the diaphragm in the third diaphragm region; and / or The maximum value of the width of the first region of the diaphragm in the second diaphragm region is smaller than or equal to the minimum value of the width of the first region of the diaphragm in the third diaphragm region.

4. The battery cell according to claim 2 or 3, characterized in that: The width of the first region of the diaphragm in the first diaphragm region is 1 / 10 to 1 / 2 of the width of the first region of the diaphragm in the third diaphragm region; and / or The width of the first region of the diaphragm in the second diaphragm region is 1 / 10 to 1 / 2 of the width of the first region of the diaphragm in the third diaphragm region.

5. The battery cell according to any one of claims 2 to 4, characterized in that: The width of the first region of the diaphragm in the first diaphragm region increases gradually in a first direction away from the third diaphragm region to close to the third diaphragm region; and / or The width of the first region of the diaphragm in the second diaphragm region increases gradually in a second direction away from the third diaphragm region to close to the third diaphragm region.

6. The battery cell according to any one of claims 2 to 5, characterized in that: In the third direction from the first diaphragm region to the second diaphragm region, the width of the first region of the diaphragm in the third diaphragm region first increases and then decreases.

7. The battery cell according to any one of claims 2 to 6, characterized in that: The length of the diaphragm in the first diaphragm region is equal to 1 to 1.5 times the length of the diaphragm in the third diaphragm region; and / or The length of the diaphragm in the second diaphragm region is equal to 1 to 1.5 times the length of the diaphragm in the third diaphragm region.

8. The battery cell according to claim 7, characterized in that: The length of the diaphragm in the first diaphragm region decreases in a first direction away from the third diaphragm region to close to the third diaphragm region; and / or The length of the diaphragm in the second diaphragm region decreases in a second direction away from the third diaphragm region to close to the third diaphragm region.

9. The battery cell according to claim 8, characterized in that: In the third direction from the first diaphragm region to the second diaphragm region, the length of the diaphragm in the third diaphragm region first decreases and then increases.

10. The battery cell according to any one of claims 2 to 9, characterized in that: The distance between the boundary of the diaphragm in the first diaphragm region and the boundary of the adjacent first pole piece is 1 / 5 to 1 / 2 of the distance between the boundary of the diaphragm in the third diaphragm region and the boundary of the adjacent first pole piece; and / or The distance between the boundary of the diaphragm in the second diaphragm region and the boundary of the adjacent first pole piece is 1 / 5 to 1 / 2 of the distance between the boundary of the diaphragm in the third diaphragm region and the boundary of the adjacent first pole piece.

11. The battery cell according to claim 10, characterized in that: In a first direction away from the third diaphragm region to close to the third diaphragm region, the distance between the boundary of the diaphragm in the first diaphragm region and the boundary of the adjacent first pole piece decreases; and / or In the second direction from away from the third diaphragm region to close to the third diaphragm region, the distance between the boundary of the diaphragm in the second diaphragm region and the boundary of the adjacent first pole piece decreases gradually.

12. The battery cell according to any one of claims 1 to 11, characterized in that: The at least one diaphragm includes a plurality of diaphragms, and one end of at least two diaphragms of the plurality of diaphragms are gathered at one side of the battery core; One ends of the at least two diaphragms are bonded.

13. The battery cell according to claim 12, characterized in that: One ends of the plurality of separators are gathered at a middle portion of one side of the battery cell.

14. The battery cell according to any one of claims 1 to 13, characterized in that: The refractive index of the diaphragm substrate in the main region is 1.49 to 1.60, and / or The refractive index of the diaphragm substrate in the first region is less than or equal to 1.

40.

15. The battery cell according to any one of claims 1 to 14, characterized in that: The first region has a harderness greater than that of the main region.

16. The battery cell according to any one of claims 1 to 15, characterized in that: The absolute value of the difference between the widths of the first regions of two adjacent diaphragms in the at least one diaphragm is between 0.010 mm and 1 mm.

17. A battery, characterized in that: include: case; And the battery cell according to any one of claims 1 to 16, wherein the battery cell is arranged in the shell.

18. A battery module, characterized in that: The invention comprises a plurality of batteries, each of which is the battery according to claim 17.

19. A battery pack, characterized in that: It comprises a plurality of battery modules, each of the plurality of battery modules being the battery module according to claim 18.

20. An electronic product, characterized in that: The battery as claimed in claim 17 is used to provide electrical energy for the electronic product.

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