Battery cell assembly, battery, and electric device

Abstract

The utility model relates to a battery technical field especially relates to a kind of electric core subassembly, battery and electric device, it include: positive sheet, negative sheet and the diaphragm being set between positive sheet and negative sheet;Positive sheet includes positive sheet ontology and positive pole lug, and positive pole lug is set in the one end of positive sheet ontology;Negative sheet includes negative sheet ontology and negative pole lug, and negative pole lug is set in the one end of negative sheet ontology;The heat shrinkage temperature of the first area of diaphragm is higher than the heat shrinkage temperature of second area;First area is the area of diaphragm within the preset range from first edge, wherein, first edge is the edge of diaphragm close to positive pole lug and / or negative pole lug;Second area is the area of diaphragm except first area.The utility model solves the battery electric core in relevant technology, when adjacent battery package occurs thermal runaway, will be connected gradually heated pole, lead to faster thermal runaway, and then lead to the problem of fast heat spread speed.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a cell assembly, a battery, and an electrical device. Background Technology

[0002] In existing battery packs, individual cells are connected to terminals via conductive components to achieve cell assembly. However, in this structure, when a single cell experiences thermal runaway, the conductive components can easily transfer heat rapidly through the terminals to the connected cells, causing the connected cells to fail quickly and resulting in a rapid heat spread problem. Utility Model Content

[0003] Therefore, the technical problem to be solved by this utility model is that in the related technology, when the battery cell is thermally runaway in an adjacent battery pack, it will be gradually heated by the connected terminals, resulting in rapid thermal runaway and thus rapid heat spread. The present invention provides a battery cell assembly, a battery and an electrical device.

[0004] In a first aspect, this utility model provides a battery cell assembly, comprising: a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet includes a positive electrode sheet body and a positive electrode tab, the positive electrode tab being disposed at one end of the positive electrode sheet body; the negative electrode sheet includes a negative electrode sheet body and a negative electrode tab, the negative electrode tab being disposed at one end of the negative electrode sheet body; the heat shrinkage temperature of a first region of the separator is higher than the heat shrinkage temperature of a second region; the first region is the region of the separator within a predetermined range from a first edge, wherein the first edge is the edge of the separator near the positive electrode tab and / or the negative electrode tab; the second region is the region of the separator other than the first region.

[0005] In one embodiment of the present invention, the diaphragm includes a diaphragm substrate and a coating layered together; the heat shrinkage temperature of the diaphragm substrate in the first region is greater than the heat shrinkage temperature of the diaphragm substrate in the second region; and / or, the coating thickness in the first region is greater than the coating thickness in the second region.

[0006] In one embodiment of the present invention, the diaphragm includes a diaphragm substrate and a coating layered together; the coating thickness in the first region is greater than the coating thickness in the second region, and the thickness of the diaphragm substrate in the first region is less than the thickness of the diaphragm substrate in the second region.

[0007] In one embodiment of the present invention, the dimension of the first region along the first direction is smaller than the dimension of the second region along the first direction; the first direction is the direction on the diaphragm that is perpendicular to the first edge of the diaphragm.

[0008] In one embodiment of this utility model, the dimension A of the first region in the first direction is 10mm-30mm.

[0009] In one embodiment of this utility model, the projection of the second edge of the positive electrode body near the positive electrode tab onto the separator and the projection of the third edge of the negative electrode body near the negative electrode tab onto the separator are both within the range of the first region; the projection of the fourth edge of the positive electrode body away from the positive electrode tab onto the separator and the projection of the fifth edge of the negative electrode body away from the negative electrode tab onto the separator are both within the range of the second region.

[0010] In one embodiment of this utility model, a positive electrode active material layer is disposed on the portion of the positive electrode body and the portion of the positive electrode tab closest to the positive electrode body, and a negative electrode active material layer is disposed on the portion of the negative electrode body and the portion of the negative electrode tab closest to the negative electrode body; the sixth edge of the positive electrode active material layer near the positive electrode tab does not extend beyond the first edge of the separator, and the seventh edge of the negative electrode active material layer near the negative electrode tab does not extend beyond the first edge of the separator; the projection of the sixth edge of the positive electrode active material layer on the separator and the projection of the seventh edge of the negative electrode active material layer on the separator are both within the range of the first region.

[0011] In one embodiment of the present invention, the positive electrode and / or the negative electrode further includes an insulating layer, the insulating layer being at least partially located on the positive electrode body and / or the negative electrode body, and the orthogonal projection of the insulating layer on the separator being located in the first region.

[0012] Secondly, this utility model also provides a battery, including a cell assembly as described in any one of the above-mentioned embodiments.

[0013] Thirdly, this utility model also provides an electrical device, including the aforementioned battery.

[0014] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial effects: The thermal shrinkage temperature of the first region near the tab on the cell electrode is higher than that of the second region, so that the first region, which is preferentially heated during external heat transfer, has higher thermal stability, thereby avoiding battery thermal runaway, prolonging the thermal runaway time, and thus reducing the rate of heat propagation. This solves the problem in related technologies where, when a thermal runaway occurs in an adjacent battery pack, the connected electrode post gradually heats up, leading to rapid thermal runaway and consequently, a fast rate of heat propagation. Attached Figure Description

[0015] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the structure of a battery cell assembly in the prior art;

[0017] Figure 2 This is a schematic diagram of the diaphragm in an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of a diaphragm structure in an embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of another diaphragm structure in an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of the battery cell assembly at the positive electrode tab in an embodiment of this utility model;

[0021] Figure 6 This is a schematic diagram of the battery cell assembly at the negative electrode tab in an embodiment of this utility model;

[0022] Figure 7 This is a schematic diagram of the battery cell assembly at the non-tab location in an embodiment of this utility model.

[0023] Figure 8 This is a schematic diagram of the battery of this utility model;

[0024] Figure 9 This is a schematic diagram of the battery pack of this utility model;

[0025] Figure 10 This is a schematic diagram of the electrical device of this utility model.

[0026] Explanation of reference numerals in the instruction manual:

[0027] 1. Positive electrode sheet; 11. Positive electrode sheet body; 12. Positive electrode tab; 13. Positive electrode active material layer; 14. Positive electrode current collector; 2. Negative electrode sheet; 21. Negative electrode sheet body; 22. Negative electrode tab; 23. Negative electrode active material layer; 24. Negative electrode current collector; 3. Separator; 31. First region; 32. Second region; 33. Separator substrate; 34. Coating; 4. Insulating layer; 41. First insulating layer; 42. Second insulating layer; 5. Battery; 51. Top cover plate; 52. Cell assembly; 53. Insulating film; 54. Bottom support plate; 55. Housing; 56. Film; 6. Battery pack; 7. Electrical device. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0029] In related technologies, batteries are often used in groups, that is, the positive and negative terminals of each battery are connected through a busbar to achieve series and parallel connection of multiple batteries. However, since the busbar is made of metal and there are heat insulation components between the batteries, when a single battery experiences thermal runaway, heat will be conducted to adjacent batteries through the busbar, causing heat propagation.

[0030] Specifically, once a single battery cell in the battery pack experiences thermal runaway, the released heat is rapidly transferred to connected battery cells via the busbar, and then quickly conducted to the internal battery cell assembly through the metal terminals and tabs. This causes the separator 3 near the tabs to melt, creating damage and voids. A short circuit occurs between the corresponding positive electrode 1 and negative electrode 2, triggering thermal runaway in the battery cell, which then propagates in the same manner. Because the busbar connects multiple batteries together, this process causes thermal runaway to spread rapidly.

[0031] In particular, lithium-ion batteries are trending towards increasing heat dissipation to reduce costs. However, the higher the battery capacity, the greater the energy released during thermal runaway, exponentially increasing the difficulty of preventing thermal propagation between batteries. To improve energy density, high-capacity cells in related technologies typically employ designs such as "reducing separator thickness," "increasing the compaction density of active materials," and "increasing electrolyte injection volume." While these designs reduce costs and increase capacity, they significantly lower the thermal runaway trigger threshold. Increasing the thermal runaway trigger threshold would inevitably affect battery performance.

[0032] Therefore, this utility model provides a battery cell assembly that reduces the difficulty of heat spread protection without affecting the overall performance of the battery cell. (Refer to...) Figures 3 to 7 As shown, a battery cell assembly of the present invention includes: a positive electrode 1, a negative electrode 2, and a separator 3 disposed between the positive electrode 1 and the negative electrode 2.

[0033] A single battery cell includes the cell assembly and the electrolyte, such as Figures 1 to 2 As shown, the battery cell assembly consists of a positive electrode 1, a negative electrode 2, and a separator 3. The battery cell primarily functions by the movement of metal ions between the positive electrode 1 and the negative electrode 2. The positive electrode 1, separator 3, and negative electrode 2 are stacked together. The separator 3 serves two functions: one is as an insulating layer to prevent short circuits within the battery cell caused by contact between the positive electrode 1 and the negative electrode 2; the other is as a semi-permeable layer to prevent larger molecules from passing through while allowing smaller charged ions to pass through.

[0034] To ensure insulation between the positive and negative electrodes, the edge of the separator 3 extends beyond the edges of the positive and negative electrodes, but does not exceed the edge of the tab, to prevent short circuits caused by contact between the positive and negative electrodes. To ensure sufficient intercalation space for lithium ions, the edge of the negative electrode active material layer extends beyond the edge of the positive electrode active material layer. Specifically, the edges of the negative electrode 2 extend beyond the edge of the positive electrode 1, and the edges of the negative electrode 2 are lower than the edge of the positive electrode 1. However, the edge of the negative electrode active material layer extends beyond the edge of the positive electrode active material layer. In actual structure, the edge of the negative electrode active material layer is located within the insulating layer of the positive electrode.

[0035] However, the material of the separator 3 is generally polyolefin, including polyethylene (PE) or polypropylene (PP). Polyolefin has a low heat resistance temperature and is easily damaged by heat, which can cause a short circuit between the positive electrode 1 and the negative electrode 2, resulting in thermal failure.

[0036] Some separators 3 can also be coated to improve performance. For example, inorganic coatings, such as aluminum oxide (Al2O3) and silicon dioxide (SiO2), can improve high-temperature resistance, reaching temperatures above 200℃, and resistance to electrolyte wetting. Organic coatings, such as PVDF (polyvinylidene fluoride) and aramid, can enhance adhesion to the positive and negative electrodes and improve cycle life. However, their effect on increasing the thermal failure temperature of the separator 3 is limited.

[0037] The positive electrode 1 includes a positive current collector 14 and a positive active material layer 13. The positive active material layer 13 is coated on the surface of the positive current collector 14, and the positive current collector 14 without the positive active material layer 13 serves as the positive electrode tab 12. Taking a lithium-ion battery as an example, the material of the positive current collector 14 can be aluminum, and the positive active material layer 13 can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc.

[0038] The negative electrode 2 includes a negative current collector 24 and a negative active material layer 23. The negative active material layer 23 is coated on the surface of the negative current collector 24, and the negative current collector 24 without the negative active material layer 23 serves as a negative electrode tab 22. The material of the negative current collector 24 can be copper, and the negative active material layer 23 can be carbon or silicon, etc. To ensure that a large current can be passed without melting, there are multiple positive electrode tabs 12 stacked together, and there are multiple negative electrode tabs 22 stacked together.

[0039] The positive electrode 1 and the negative electrode 2 have similar structures, with the current collector serving as the main body, multiple tabs leading out from the current collector, and an active material layer disposed on the main body. That is, the positive electrode 1 includes a positive electrode body 11 and a positive tab 12, with the positive tab 12 disposed at one end of the positive electrode body 11; the negative electrode 2 includes a negative electrode body 21 and a negative tab 22, with the negative tab 22 disposed at one end of the negative electrode body 21.

[0040] The positive tab 12 is connected to the positive terminal of the battery, and the negative tab 22 is connected to the negative terminal of the battery. The positive electrode 1 and the negative electrode 2 are separated by a separator 3. Both the tabs and the terminal are made of metal with high thermal conductivity. The area near the positive and negative tabs is easily heated to the point of failure by the transferred heat, causing a short circuit between the positive electrode 1 and the negative electrode 2, which in turn leads to thermal failure of the battery.

[0041] Therefore, in this embodiment, the diaphragm 3 is divided into a first region 31 and a second region 32. The first region 31 is the region of the diaphragm 3 within a predetermined range from the first edge, wherein the first edge is the edge of the diaphragm 3 near the positive electrode tab 12 and / or the negative electrode tab 22; the second region 32 is the region of the diaphragm 3 other than the first region 31.

[0042] The heat shrinkage temperature of the first region 31 of the diaphragm 3 is set higher than that of the second region 32. This results in the first region 31, which is closer to the tab, having higher thermal stability, while the second region 32 does not need to have excessively high thermal stability. Targeted heat insulation not only improves thermal stability, extends thermal failure time, and reduces the rate of heat spread, but also offers better economic benefits, with lower costs compared to using a method that emphasizes high thermal stability throughout.

[0043] like Figure 3 As shown, in an optional embodiment, the diaphragm 3 includes a diaphragm substrate 33 and a coating 34 stacked together; the heat shrinkage temperature of the diaphragm substrate 33 in the first region 31 is greater than the heat shrinkage temperature of the diaphragm substrate 33 in the second region 32; and / or, the thickness of the coating 34 in the first region 31 is greater than the thickness of the coating 34 in the second region 32.

[0044] The diaphragm 3 includes a diaphragm substrate 33 and a coating 34 stacked together. To improve the heat insulation performance of the first region 31 of the diaphragm 3, it can be improved from two angles: increasing the heat shrinkage temperature of the diaphragm substrate 33 so that the heat shrinkage temperature of the diaphragm substrate 33 in the first region 31 is greater than that in the second region 32; and increasing the heat insulation capacity of the coating 34 so that the thickness of the coating 34 in the first region 31 is greater than that in the second region 32.

[0045] The two approaches described above can be used individually or simultaneously to increase the heat shrinkage temperature of the first region 31, making it higher than the heat shrinkage temperature of the second region 32.

[0046] Increasing the heat shrinkage temperature of the diaphragm substrate 33 (with polyolefin as its core) can be achieved by means of molecular structure optimization, physical modification, and composite reinforcement, thereby enhancing the structural stability of the substrate at high temperatures and delaying or inhibiting its tendency to shrink under heat. At the same time, the core properties of the diaphragm 3, such as ion conductivity and mechanical strength, must also be taken into account.

[0047] To improve the heat insulation capability of coating 34, one could replace it with a coating 34 that offers better heat insulation, or increase the thickness of coating 34. However, since there is no clear boundary between the first region 31 and the second region 32, changing the coating material might increase the difficulty of applying the coating to the membrane substrate 33. Increasing the thickness is a more direct and simpler approach, and it can also effectively improve the heat insulation performance of coating 34, thereby increasing the heat shrinkage temperature of the membrane 3.

[0048] like Figure 4 As shown, in an optional embodiment, the diaphragm 3 includes a diaphragm substrate 33 and a coating 34 stacked together; the thickness of the coating 34 in the first region 31 is greater than the thickness of the coating 34 in the second region 32, and the thickness of the diaphragm substrate 33 in the first region 31 is less than the thickness of the diaphragm substrate 33 in the second region 32.

[0049] In increasing the thickness of the coating 34 as described above, to avoid changes in the size and shape of the separator 3, which could lead to new problems, such as an uneven surface that hinders adhesion to the positive and negative electrode plates 1 and 2, gaps may exist between the separator 3 and the plates. This would not only disrupt the tight lithium-ion conduction pathway, resulting in a significant reduction in electrochemical reaction efficiency, but also cause structural instability, making it prone to problems during assembly and use. Furthermore, in the event of electrolyte shortage, lithium plating may occur, puncturing the separator and causing runaway.

[0050] To address this, the thickness of the separator substrate 33 in the first region 31 is reduced to decrease the surface unevenness of the separator 3, making the overall thickness of the separator 3 in the first region 31 more consistent with the overall thickness of the separator in the second region 32. This ensures the chemical reaction efficiency and structural stability of the battery cell assembly during use and, to some extent, avoids safety hazards.

[0051] Preferably, the sum of the thickness of the coating 34 in the first region 31 and the thickness of the diaphragm substrate 33 in the first region 31 is equal to the sum of the thickness of the coating 34 in the second region 32 and the thickness of the diaphragm substrate 33 in the second region 32. That is, the overall thickness of the diaphragm 3 in the first region 31 is consistent with the overall thickness of the diaphragm in the second region 32, so that the morphology of the diaphragm 3 before and after raising the first region 31 is consistent with the original.

[0052] As an optional embodiment, the dimension of the first region 31 along the first direction is smaller than the dimension of the second region 32 along the first direction; the first direction is the direction on the diaphragm 3 that is perpendicular to the first edge of the diaphragm 3.

[0053] Because the first region 31 requires a higher thermal failure temperature, more materials and higher costs are needed to modify the diaphragm substrate 33 and coating 34. Therefore, the size of the first region 31 will not exceed half the overall size of the diaphragm 3 in the first direction. That is, the size of the first region 31 along the first direction is smaller than the size of the second region 32 along the first direction.

[0054] like Figure 2 As shown, the separator 3 is rectangular in shape before the positive electrode 1 and the negative electrode 2, and has no distinction between positive and negative. However, after the first region 31 is set, the end near the first region 31 needs to be close to the end of the tabs of the positive and negative electrodes during installation. It should be noted that in this embodiment, the positive and negative tabs of the cell assembly are both located at the same end of the positive and negative electrodes.

[0055] Theoretically, there are also cases where the tabs of the positive and negative electrodes are set at opposite ends. In this case, the two edges of the separator 3 in the first direction are set as the first region 31, and the second region 32 is set between the two first regions 31.

[0056] As an optional embodiment, the dimension A of the first region 31 in the first direction is 10mm-30mm.

[0057] The battery in this embodiment is a lithium iron phosphate battery, with a thickness of 10mm-40mm, a width of 100mm-200mm, and a height of 80mm-180mm. The dimension of the separator 3 in the first direction, that is, the height in the height direction, is close to the height of the battery described above.

[0058] The terminals and tabs are typically made of copper. Considering heat loss during heat transfer and the battery size, the dimension A of the first region in the first direction is set to 10mm-30mm. This can slow down heat spread and avoid excessively increasing costs. Specific dimensions can be 10mm, 15mm, 20mm, 25mm, 30mm, etc.

[0059] As an optional embodiment, the projection of the second edge of the positive electrode body 11 near the positive electrode tab 12 onto the diaphragm 3, and the projection of the third edge of the negative electrode body 21 near the negative electrode tab 22 onto the diaphragm 3, are both within the range of the first region 31.

[0060] like Figure 5 As shown, the second edge of the positive electrode body 11 near the positive electrode tab 12 is located in the first region 31 in the first direction relative to the height of the separator 3. In this way, the first region 31 can be guaranteed to correspond to the high-temperature position at the connection between the positive electrode tab 12 and the positive electrode body 11, effectively delaying the spread of heat.

[0061] Similarly, such as Figure 6As shown, the third edge of the negative electrode body 21 near the negative electrode tab 22 is located within the first region 31 in the first direction relative to the height of the diaphragm 3.

[0062] The projection of the fourth edge of the positive electrode body 11 away from the positive electrode tab 12 onto the diaphragm 3, and the projection of the fifth edge of the negative electrode body 21 away from the negative electrode tab 22 onto the diaphragm 3, are both within the range of the second region 32.

[0063] like Figure 5 As shown, the fourth edge of the positive electrode body 11, which is away from the positive electrode tab 12, is located in the second region 32 in the first direction relative to the height of the separator 3. This is because the fourth edge is away from the positive electrode tab 12 and belongs to the area that is not prone to high temperature. By corresponding the location that is not prone to high temperature at the connection point between the positive electrode tab 12 and the positive electrode body 11 to the second region 32, the cost reduction effect can be effectively achieved.

[0064] Similarly, such as Figure 6 As shown, the fifth edge of the negative electrode body 21, away from the negative electrode tab 22, is located within the second region 32 in the first direction relative to the height of the diaphragm 3.

[0065] As an optional embodiment, a positive electrode active material layer 13 is provided on the portion of the positive electrode body 11 and the positive electrode tab 12 near the positive electrode body 11, and a negative electrode active material layer 23 is provided on the portion of the negative electrode body 21 and the negative electrode tab 22 near the negative electrode body 21.

[0066] like Figure 5 As shown, the sixth edge of the positive electrode active material layer 13 near the positive electrode tab 12 does not extend beyond the first edge of the separator 3, and the seventh edge of the negative electrode active material layer 23 near the negative electrode tab 22 does not extend beyond the first edge of the separator 3.

[0067] That is, the sixth edge of the positive electrode active material layer 13 is close to the positive electrode tab 12 and does not exceed the first edge of the diaphragm 3 in the first direction. This ensures that the sixth edge, which is prone to high temperature, is accurately located in the first region 31. This not only effectively delays the spread of heat, but also prevents the positive electrode active material layer 13 and the negative electrode active material layer 23 from short-circuiting.

[0068] Similarly, such as Figure 6 As shown, the negative electrode active material layer 23 is close to the seventh edge of the negative electrode tab 22, and in the first direction, it does not extend beyond the first edge of the diaphragm 3.

[0069] That is, the projection of the sixth edge of the positive electrode active material layer 13 onto the separator 3 and the projection of the seventh edge of the negative electrode active material layer 23 onto the separator 3 are both within the range of the first region 31.

[0070] As an optional embodiment, the positive electrode 1 and / or negative electrode 2 further include an insulating layer 4, which is at least partially located on the positive electrode body 11 and / or negative electrode body 21, and the orthogonal projection of the insulating layer 4 on the separator 3 is located within the first region 31.

[0071] Specifically, a first insulating layer 41 is provided on the area of ​​the positive electrode body 11 other than the positive electrode active material layer 13, and / or on the negative electrode body 21 other than the negative electrode active material layer 23.

[0072] And / or, the area on the positive electrode tab 12 other than the positive electrode active material layer 13, and / or the area on the negative electrode tab 22 other than the negative electrode active material layer 23, are provided with a second insulating layer 42.

[0073] Taking lithium-ion batteries as an example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. When the current collector is cut, burrs are easily generated, which can easily scratch the separator. Therefore, an insulating layer (usually a ceramic layer) is coated on the edge of the current collector to prevent the burrs from piercing the electrode and causing a short circuit.

[0074] like Figures 5 to 7 As shown, the insulating layer 4 is at least partially located on the positive electrode body 11 and / or the negative electrode body 21, and the height of the insulating layer 4 near the edge of the positive electrode tab 12 and / or the negative electrode tab 22 in the first direction is within the height range of the first region 31 of the separator 3.

[0075] This embodiment also provides a battery, including any of the above-described cell assemblies.

[0076] like Figure 8 As shown, the battery cell includes a top cover plate 51, a cell assembly 52, an insulating film 53, a bottom support plate 54, a housing 55, and a protective film 56. The top cover plate 51 has positive and negative terminals and is mounted on the housing 55, housing the cell assembly 52 and electrolyte in a closed space. The insulating film 53 and the bottom support plate 54 provide insulation between the cell assembly 52 and the housing 55 and the top cover plate 51. The protective film 56 is applied to the outer surface of the housing 55.

[0077] The battery cell assembly 52 consists of a positive electrode 1, a negative electrode 2, and a separator 3. The battery cell mainly relies on the movement of metal ions between the positive electrode 1 and the negative electrode 2 to function.

[0078] Taking a lithium-ion battery as an example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can be passed without melting, there are multiple positive electrode tabs 12 stacked together, and multiple negative electrode tabs 22 stacked together.

[0079] To ensure insulation between the positive and negative electrodes, the edge of the separator 3 must extend beyond the edges of the positive and negative electrodes (but not beyond the edges of the tabs) to prevent short circuits caused by contact between the positive and negative electrodes. To ensure sufficient intercalation space for lithium ions, the edge of the negative electrode active material layer 23 must extend beyond the edge of the positive electrode active material layer 13.

[0080] Specifically, the edges of the negative electrode 2 extend beyond the edges of the positive electrode 1. The edges of the negative electrode 2 are lower than the edges of the positive electrode 1, but the edges of the negative electrode active material layer 23 extend beyond the edges of the positive electrode active material layer 13. In actual structure, the edges of the negative electrode active material layer 23 are located within the insulating layer of the positive electrode. Because burrs are easily generated when the positive electrode current collector 14 (aluminum) is cut, the edges of the positive electrode current collector 14 are coated with an insulating layer 4 to prevent burrs from piercing the electrode and causing a short circuit.

[0081] This embodiment also provides a battery pack, including a busbar and multiple batteries. The busbar connects the terminals of the multiple batteries to achieve series and parallel connection of different batteries.

[0082] like Figure 9 As shown, multiple batteries 5 are connected in series or parallel via electrical connectors to form a battery pack 6, which supplies power to the electrical device 7. The battery pack 6 can also house the connected batteries 5 through a casing. The casing can also be configured to connect to the internal structure of the electrical device 7, so that the battery pack 6 is used in conjunction with the electrical device 7.

[0083] When a battery cell in a battery pack experiences thermal runaway, heat is transferred between the cells through the electrical connections between the terminals and busbars. When implementing thermal propagation protection for battery packs, thermal pads are typically used to reduce the thermal conductivity of the large surfaces between adjacent cells. However, due to the series connection requirements between the cells, the electrical connections between the terminals and busbars also form highly thermally conductive connections, making it difficult to increase thermal insulation measures.

[0084] Heat conducted through the pole is more likely to form high temperature in the first region near the pole, so the diaphragm with the first region 31 set on the diaphragm 3 of the telecommunications component has stronger temperature resistance.

[0085] Replacing the entire separator 3 with a more thermally stable solution typically requires higher costs or degrades the power performance and energy density of the battery cell assembly. Furthermore, if the overall thermal stability is stronger, when the first cell experiences thermal runaway, the temperature of adjacent cells may already be at a dangerously high level, which is also detrimental to preventing thermal propagation.

[0086] When the separator 3 in the second region 32 is configured to have poor thermal stability, while the separator in the first region 31 has good thermal stability, the overall thermal stability of the battery cell is not strong. When the first battery cell is triggered to thermal runaway, the temperature of the adjacent battery cells is relatively low and within a safe range. Furthermore, the heat conducted through the electrode post will first raise the temperature of the first region 31, and since the separator 3 in the first region 31 has better thermal stability, the risk of heat propagation is reduced.

[0087] This embodiment also provides an electrical device, including the battery described above.

[0088] like Figure 10 As shown, the power-consuming device 7 can be a mobile phone, tablet, laptop, electric toy, power tool, electric vehicle, electric car, ship, spacecraft, or other electronic device or device that requires battery power. As an example, the power-consuming device 7 is a vehicle, with a battery 5 installed inside. The battery 5 can directly power the vehicle, or it can form a battery pack 6 to power the vehicle.

[0089] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to be actual. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A battery cell assembly, characterized in that, include: A positive electrode (1), a negative electrode (2), and a separator (3) disposed between the positive electrode (1) and the negative electrode (2). The positive electrode (1) includes a positive electrode body (11) and a positive electrode tab (12), the positive electrode tab (12) being disposed at one end of the positive electrode body (11); the negative electrode (2) includes a negative electrode body (21) and a negative electrode tab (22), the negative electrode tab (22) being disposed at one end of the negative electrode body (21); The heat shrinkage temperature of the first region (31) of the diaphragm (3) is higher than that of the second region (32); The first region (31) is the region within a predetermined range of the diaphragm (3) from the first edge, wherein the first edge is the edge of the diaphragm (3) near the positive electrode tab (12) and / or the negative electrode tab (22); The second region (32) is the region of the diaphragm (3) other than the first region (31).

2. The cell assembly according to claim 1, characterized in that, The diaphragm (3) includes a diaphragm substrate (33) and a coating (34) stacked together. The heat shrinkage temperature of the diaphragm substrate (33) in the first region (31) is greater than that of the diaphragm substrate (33) in the second region (32); And / or, the coating (34) thickness of the first region (31) is greater than the coating (34) thickness of the second region (32).

3. The battery cell assembly according to claim 1, characterized in that, The diaphragm (3) includes a diaphragm substrate (33) and a coating (34) stacked together. The coating (34) thickness of the first region (31) is greater than the coating (34) thickness of the second region (32), and the thickness of the diaphragm substrate (33) of the first region (31) is less than the thickness of the diaphragm substrate (33) of the second region (32).

4. The cell assembly according to claim 1, characterized in that, The dimension of the first region (31) along the first direction is smaller than the dimension of the second region (32) along the first direction; The first direction is the direction on the diaphragm (3) that is perpendicular to the first edge of the diaphragm (3).

5. The cell assembly according to claim 4, characterized in that, The first region (31) has a size A of 10mm-30mm in the first direction.

6. The cell assembly according to claim 1, characterized in that, The projection of the second edge of the positive electrode body (11) near the positive electrode tab (12) onto the diaphragm (3) and the projection of the third edge of the negative electrode body (21) near the negative electrode tab (22) onto the diaphragm (3) are both within the range of the first region (31); The projection of the fourth edge of the positive electrode body (11) away from the positive electrode tab (12) onto the diaphragm (3) and the projection of the fifth edge of the negative electrode body (21) away from the negative electrode tab (22) onto the diaphragm (3) are both within the range of the second region (32).

7. The cell assembly according to claim 6, characterized in that, The positive electrode body (11) and the positive electrode tab (12) are provided with a positive electrode active material layer (13) on the portion near the positive electrode body (11), and the negative electrode body (21) and the negative electrode tab (22) are provided with a negative electrode active material layer (23) on the portion near the negative electrode body (21). The sixth edge of the positive electrode active material layer (13) near the positive electrode tab (12) does not extend beyond the first edge of the diaphragm (3), and the seventh edge of the negative electrode active material layer (23) near the negative electrode tab (22) does not extend beyond the first edge of the diaphragm (3). The projection of the sixth edge of the positive electrode active material layer (13) onto the separator (3) and the projection of the seventh edge of the negative electrode active material layer (23) onto the separator (3) are both within the range of the first region (31).

8. The cell assembly according to claim 7, characterized in that, The positive electrode (1) and / or the negative electrode (2) further include an insulating layer (4), which is at least partially located on the positive electrode body (11) and / or the negative electrode body (21), and the orthogonal projection of the insulating layer (4) on the diaphragm (3) is located within the first region (31).

9. A battery, characterized in that, Includes the cell assembly as described in any one of claims 1 to 8.

10. An electrical appliance, characterized in that, Includes the battery as described in claim 9.

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