Battery cell and secondary battery thereof

Abstract

The utility model provides a battery cell and a secondary battery thereof. The battery cell comprises a positive plate, a negative plate and a diaphragm; the positive plate is provided with a positive tab; in the extension direction of the positive tab, the edges of the two sides of the diaphragm exceed the edges of the two sides of the positive plate; a first hot ironing area and a second hot ironing area are respectively arranged in the two opposite side areas, exceeding the positive plate, of the diaphragm, and the area where the first hot ironing area and the second hot ironing area are located does not coincide with the orthographic projection area of the positive lug on the diaphragm; the negative plate is provided with a negative tab; in the extension direction of the negative tab, the edges of the two sides of the diaphragm exceed the edges of the two sides of the negative plate; a third hot ironing area and a fourth hot ironing area are respectively arranged in the two opposite side areas, exceeding the negative plate, of the diaphragm, and the area where the third hot ironing area and the fourth hot ironing area are located does not coincide with the orthographic projection area of the negative lug on the diaphragm. According to the utility model, the blanching area is arranged on the diaphragm, so that external particles can be prevented from entering the battery cell, and the pole piece can be fixed.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries and relates to a battery core and a secondary battery thereof. Background Art

[0002] The common commercial lithium-ion or sodium-ion battery separator is PP or PE, which is placed inside the shell by winding or stacking. The shell material is roughly divided into aluminum plastic film, steel shell, aluminum shell or polymer plastic, etc. The separator not only prevents the positive and negative electrodes from direct contact with each other, but also transmits the lithium ions or sodium ions in the electrolyte in a rocking chair. At the same time, the separator forms a two-dimensional overhang insulation on both sides of the positive and negative electrodes.

[0003] In the battery cell obtained by winding or lamination, the top and bottom of the diaphragm are open in the extension direction of the pole ear, which is convenient for the injection and infiltration of electrolyte and the formation of airway for normal exhaust. However, the open state provides a realistic space and possibility for external dust and metal debris to enter the battery cell, and for internal particles to overflow to the outside of the battery cell, and is also not conducive to the fixation of the pole piece. In addition, the extra diaphragm occupies the internal space of the battery cell, resulting in a decrease in the energy density of the battery cell. Therefore, it is urgent to solve the above problems. Utility Model Content

[0004] In view of the shortcomings of the prior art, the utility model aims to provide a battery cell and a secondary battery thereof. The utility model can prevent external particles from entering the battery cell and internal particles from overflowing by setting a hot zone on the diaphragm, and can also fix the pole piece and improve the energy density.

[0005] To achieve this purpose, the utility model adopts the following technical solutions:

[0006] In a first aspect, the utility model provides a battery cell, the battery cell comprising a positive electrode sheet, a negative electrode sheet and a separator located between the positive electrode sheet and the negative electrode sheet;

[0007] The positive electrode sheet has a positive electrode ear; in the extension direction of the positive electrode ear, both side edges of the diaphragm exceed the side edges of the positive electrode sheet; the diaphragm is provided with a first hot-scalding area and a second hot-scalding area in the two opposite side regions beyond the positive electrode sheet, respectively, and the area where the first hot-scalding area and the second hot-scalding area are located does not overlap with the orthographic projection area of ​​the positive electrode ear on the diaphragm;

[0008] The negative electrode sheet has a negative electrode ear; in the extension direction of the negative electrode ear, both side edges of the diaphragm exceed the side edges of the negative electrode sheet; the diaphragm is respectively provided with a third hot-scalding area and a fourth hot-scalding area in the opposite side areas beyond the negative electrode sheet, and the area where the third hot-scalding area and the fourth hot-scalding area are located does not overlap with the positive projection area of ​​the negative electrode ear on the diaphragm.

[0009] The battery cell provided by the utility model comprises a positive electrode sheet, a negative electrode sheet and a diaphragm. A hot-scalding area is provided in the area where the diaphragm exceeds the positive and negative electrode sheets along the extension direction of the pole ears. The diaphragm material in the hot-scalding area is fixed by hot-scalding, which has the following advantages:

[0010] 1) The hot zone is set on the diaphragm to reduce the height of the battery cell, thereby further increasing the size of the pole piece and thus improving the energy density of the battery cell;

[0011] 2) The hot zone is set on the diaphragm to prevent the risk of sodium / lithium precipitation caused by the movement and displacement of the pole pieces, further improving the safety of the battery cell;

[0012] 3) A hot zone is set on the diaphragm along the extension direction of the pole ear, which can effectively physically block and isolate external solid dust (such as copper and aluminum debris, stripped positive and negative electrode film material pollutants or environmental dust, etc.), and prevent internal particles from overflowing, which can further reduce the self-discharge and internal short circuit risks of the battery cell, and improve the self-discharge performance and safety performance of the battery cell storage;

[0013] 4) The hot-scalding area is set on the diaphragm, which can play a role in diversion and dredging. Compared with the presence or absence of the hot-scalding area, whether the external electrolyte is injected into the battery cell or the internal gas of the battery cell is discharged from the battery cell, the channels are fundamentally changed. When the hot-scalding area is set, the electrolyte or gas enters and exits through the ear side, and the ear side plays an important role in diversion fortress;

[0014] 5) A hot-scalding area is set on the diaphragm, which does not require tape fixation and saves costs.

[0015] Preferably, the total height of the separator beyond the positive electrode sheet is 8.5 to 9 mm.

[0016] Preferably, the first blanching zone and the second blanching zone are both arranged along the edge of the membrane.

[0017] Preferably, the heights of the first blanching zone and the second blanching zone are independently 0.5-1 mm.

[0018] Preferably, the total height of the separator beyond the negative electrode sheet is 5.5 to 6 mm.

[0019] Preferably, the third blanching zone and the fourth blanching zone are both arranged along the edge of the membrane.

[0020] Preferably, the heights of the third blanching zone and the fourth blanching zone are independently 0.5-1 mm.

[0021] Preferably, the extension direction of the positive electrode tab is parallel to the extension direction of the negative electrode tab.

[0022] Preferably, the first blanching zone and the third blanching zone are the same blanching zone, and the second blanching zone and the fourth blanching zone are the same blanching zone;

[0023] Alternatively, the first blanching zone and the fourth blanching zone are the same blanching zone, and the second blanching zone and the third blanching zone are the same blanching zone.

[0024] Preferably, the positive electrode tab and the negative electrode tab are located on the same side of the battery cell.

[0025] Preferably, the blanching zone on the side away from the positive electrode tab and the negative electrode tab includes a plurality of sub-blanching zones arranged at intervals.

[0026] Preferably, the interval between adjacent sub-scalding zones is 0.05-5 mm.

[0027] Preferably, the positive electrode tab and the negative electrode tab are located on opposite sides of the battery cell.

[0028] Preferably, the battery cell is a wound battery cell or a laminated battery cell; the battery cell comprises a plurality of positive electrode sheets, a plurality of negative electrode sheets and a plurality of separators, and a single separator is arranged between adjacent positive electrode sheets and negative electrode sheets.

[0029] In a second aspect, the utility model provides a secondary battery, wherein the secondary battery comprises the battery cell described in the first aspect.

[0030] Compared with the prior art, the beneficial effects of the utility model are:

[0031] The battery cell provided by the utility model comprises a positive electrode sheet, a negative electrode sheet and a diaphragm. A hot-scalding area is provided in the area where the diaphragm exceeds the positive and negative electrode sheets along the extension direction of the pole ears. The diaphragm material in the hot-scalding area is fixed by hot-scalding, which has the following advantages:

[0032] 1) The hot zone is set on the diaphragm to reduce the height of the battery cell, thereby further increasing the size of the pole piece and thus improving the energy density of the battery cell;

[0033] 2) The hot zone is set on the diaphragm to prevent the risk of sodium / lithium precipitation caused by the movement and displacement of the pole pieces, further improving the safety of the battery cell;

[0034] 3) A hot zone is set on the diaphragm along the extension direction of the pole ear, which can effectively physically block and isolate external solid dust (such as copper and aluminum debris, stripped positive and negative electrode film material pollutants or environmental dust, etc.), and prevent internal particles from overflowing, which can further reduce the self-discharge and internal short circuit risks of the battery cell, and improve the self-discharge performance and safety performance of the battery cell storage;

[0035] 4) The hot-scalding area is set on the diaphragm, which can play a role in diversion and dredging. Compared with the presence or absence of the hot-scalding area, whether the external electrolyte is injected into the battery cell or the internal gas of the battery cell is discharged from the battery cell, the channels are fundamentally changed. When the hot-scalding area is set, the electrolyte or gas enters and exits through the ear side, and the ear side plays an important role in diversion fortress;

[0036] 5) A hot-scalding area is set on the diaphragm, which does not require tape fixation and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the structure of a battery cell provided in Example 1 of the utility model;

[0038] Figure 2 A schematic diagram of the structure of a battery cell provided in Example 2 of the utility model;

[0039] Among them, 1-positive electrode ear; 2-negative electrode ear; 3-scalding zone A; 4-scalding zone B. DETAILED DESCRIPTION

[0040] It should be understood that, in the description of the present utility model, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0041] It should be noted that, in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "connected" and "connected" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0043] In one embodiment, the utility model provides a battery cell, the battery cell comprising a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet;

[0044] The positive electrode sheet has a positive electrode ear; in the extension direction of the positive electrode ear, both side edges of the diaphragm exceed the side edges of the positive electrode sheet; the diaphragm is provided with a first hot-scalding area and a second hot-scalding area in the two opposite side regions beyond the positive electrode sheet, respectively, and the area where the first hot-scalding area and the second hot-scalding area are located does not overlap with the orthographic projection area of ​​the positive electrode ear on the diaphragm;

[0045] The negative electrode sheet has a negative electrode ear; in the extension direction of the negative electrode ear, both side edges of the diaphragm exceed the side edges of the negative electrode sheet; the diaphragm is respectively provided with a third hot-scalding area and a fourth hot-scalding area in the opposite side areas beyond the negative electrode sheet, and the area where the third hot-scalding area and the fourth hot-scalding area are located does not overlap with the positive projection area of ​​the negative electrode ear on the diaphragm.

[0046] It should be noted that the diaphragms at the positive and negative ears are not affected by the hot zone and remain in an open state, which is convenient for the injection of electrolyte and the discharge of internal gas.

[0047] The battery cell provided by the utility model comprises a positive electrode sheet, a negative electrode sheet and a diaphragm. A hot-scalding area is provided in the area where the diaphragm exceeds the positive and negative electrode sheets along the extension direction of the pole ears. The diaphragm material in the hot-scalding area is fixed by hot-scalding, which has the following advantages:

[0048] 1) The hot zone is set on the diaphragm to reduce the height of the battery cell, thereby further increasing the size of the pole piece and thus improving the energy density of the battery cell;

[0049] 2) The hot zone is set on the diaphragm to prevent the risk of sodium / lithium precipitation caused by the movement and displacement of the pole pieces, further improving the safety of the battery cell;

[0050] 3) A hot zone is set on the diaphragm along the extension direction of the pole ear, which can effectively physically block and isolate external solid dust (such as copper and aluminum debris, stripped positive and negative electrode film material pollutants or environmental dust, etc.), and prevent internal particles from overflowing, which can further reduce the self-discharge and internal short circuit risks of the battery cell, and improve the self-discharge performance and safety performance of the battery cell storage;

[0051] 4) The hot-scalding area is set on the diaphragm, which can play a role in diversion and dredging. Compared with the presence or absence of the hot-scalding area, whether the external electrolyte is injected into the battery cell or the internal gas of the battery cell is discharged from the battery cell, the channels are fundamentally changed. When the hot-scalding area is set, the electrolyte or gas enters and exits through the ear side, and the ear side plays an important role in diversion fortress;

[0052] 5) A hot-scalding area is set on the diaphragm, which does not require tape fixation and saves costs.

[0053] The present invention does not limit the material of the diaphragm. The material of the diaphragm is, for example, PEEK, PET, polyamide, PVDF, PI, PBO, PBI, PPS, PP or PE, etc.

[0054] In one embodiment, each blanching zone is obtained by blanching. The blanching temperature matches the material of the diaphragm. For example, the blanching temperature of the PP diaphragm is set to 165°C±5°C, the blanching temperature of the PE diaphragm is set to 135°C±5°C, and the blanching temperature of the PVDF diaphragm is set to 180°C±5°C. Blades can be used for blanching.

[0055] In one embodiment, the total height of the diaphragm beyond the positive electrode plate is 8.5 to 9 mm, for example, 8.5 mm, 8.6 mm, 8.7 mm, 8.8 mm, 8.9 mm or 9 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] In one embodiment, the first blanching zone and the second blanching zone are both arranged along the edge of the membrane.

[0057] In one embodiment, the heights of the first blanching zone and the second blanching zone are independently 0.5 to 1 mm, for example, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, etc., but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] In the utility model, the sum of the heights of the first blanching zone and the second blanching zone is 1 to 2 mm, so that the height of the battery cell in the extension direction of the positive electrode ear can be reduced by 1 to 2 mm, thereby improving the energy density.

[0059] The total remaining height of the separator beyond the positive electrode sheet is calculated to be 6.5-8 mm, which is still a normal margin. Therefore, when the heights of the first blanching zone and the second blanching zone are independently 0.5-1 mm, normal separator redundancy can be guaranteed.

[0060] In one embodiment, the total height of the separator beyond the negative electrode plate is 5.5 to 6 mm, for example, 5.5 mm, 5.6 mm, 5.7 mm, 5.8 mm, 5.9 mm or 6 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] In one embodiment, the third blanching zone and the fourth blanching zone are both arranged along the edge of the membrane.

[0062] The heights of the third blanching zone and the fourth blanching zone are independently 0.5 to 1 mm, for example, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, etc., but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0063] In the utility model, the sum of the heights of the third blanching zone and the fourth blanching zone is 1 to 2 mm, so that the height of the battery cell in the extension direction of the negative electrode ear can be reduced by 1 to 2 mm, thereby improving the energy density.

[0064] The total remaining height of the separator beyond the negative electrode sheet is calculated to be 3.5-5 mm, which is still a normal margin. Therefore, when the heights of the third blanching zone and the fourth blanching zone are independently 0.5-1 mm, normal separator redundancy can be guaranteed.

[0065] In one embodiment, the extension direction of the positive electrode tab is parallel to the extension direction of the negative electrode tab.

[0066] In one embodiment, the first blanching zone and the third blanching zone are the same blanching zone, and the second blanching zone and the fourth blanching zone are the same blanching zone;

[0067] Alternatively, the first blanching zone and the fourth blanching zone are the same blanching zone, and the second blanching zone and the third blanching zone are the same blanching zone.

[0068] In the present invention, when the extension direction of the positive electrode ear is parallel to the extension direction of the negative electrode ear, only two hot-scalding areas are arranged opposite to each other on the diaphragm, and this includes two situations: the first hot-scalding area and the third hot-scalding area are the same hot-scalding area, and the second hot-scalding area and the fourth hot-scalding area are the same hot-scalding area; or, the first hot-scalding area and the fourth hot-scalding area are the same hot-scalding area, and the second hot-scalding area and the third hot-scalding area are the same hot-scalding area.

[0069] In one embodiment, the positive electrode tab and the negative electrode tab are located on the same side of the battery cell.

[0070] In one embodiment, the blanching zone on the side away from the positive electrode tab and the negative electrode tab includes a plurality of sub-blanching zones arranged at intervals.

[0071] In the present invention, when the positive electrode ear and the negative electrode ear are located on the same side of the battery cell, the blanching area on the side away from the positive electrode ear and the negative electrode ear includes a plurality of sub-blanching areas arranged at intervals, which indicates that the blanching area on this side is not completely closed, and the intervals between adjacent sub-blanching areas can be infiltrated with electrolyte.

[0072] In the present invention, the “plurality” in the plurality of blanching sub-zones refers to at least 2, such as 2, 3, 5, 10 or 15, etc.

[0073] In one embodiment, the interval between adjacent sub-scalding zones is 0.05-5 mm, for example, 0.05 mm, 0.1 mm, 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm.

[0074] In one embodiment, the positive electrode tab and the negative electrode tab are located on opposite sides of the battery cell.

[0075] In one embodiment, the battery cell is a wound battery cell or a laminated battery cell; the battery cell includes a plurality of positive electrode sheets, a plurality of negative electrode sheets and a plurality of separators, and a single separator is disposed between adjacent positive electrode sheets and negative electrode sheets. The "plurality" mentioned above refers to at least 2, such as 2, 3, 5, 10, 15, 20, 50, 80, 100 or 200, etc.

[0076] In the present invention, when the battery cell includes multiple positive plates, multiple negative plates and multiple separators, the multiple separators are all provided with a hot-scalding area, and the hot-scalding area structure of each separator is the same. When preparing the hot-scalding area, the outermost separator is directly contacted for hot-scalding.

[0077] In one embodiment, the laminated battery cell includes 20 to 50 positive electrode sheets, 21 to 51 negative electrode sheets, and 43 to 103 separators that are stacked, and a single separator is disposed between adjacent positive electrode sheets and negative electrode sheets.

[0078] In one embodiment, the utility model provides a secondary battery, wherein the secondary battery includes the battery cell described in the above embodiment.

[0079] Example 1

[0080] This embodiment provides a battery cell, specifically a square coil core, the battery cell comprising a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet;

[0081] like Figure 1 As shown, the positive electrode sheet has a positive electrode ear 1, and the negative electrode sheet has a negative electrode ear 2; the extension direction of the positive electrode ear 1 is parallel to the extension direction of the negative electrode ear 2, and the positive electrode ear 1 and the negative electrode ear 2 are located on the same side of the battery cell;

[0082] In the extension direction of the positive electrode ear 1 and the negative electrode ear 2, the two side edges of the diaphragm simultaneously exceed the two side edges of the positive electrode sheet and the negative electrode sheet, and the total height of the area where the diaphragm exceeds the positive electrode sheet is 8.5 mm, and the total height of the area where the diaphragm exceeds the negative electrode sheet is 5.5 mm; the two opposite side areas where the diaphragm exceeds the positive electrode sheet and the negative electrode sheet are respectively recorded as the first area and the second area, the first area is the side close to the positive electrode ear 1 and the negative electrode ear 2, and the second area is the side away from the positive electrode ear 1 and the negative electrode ear 2; in the first area, a first hot blanching area and a third hot blanching area are arranged along the edge of the diaphragm, and the first hot blanching area and the third hot blanching area are the same hot blanching area, recorded as hot blanching area A3; in the second area, a second hot blanching area and a fourth hot blanching area are arranged along the edge of the diaphragm, and the second hot blanching area and the fourth hot blanching area are the same hot blanching area, recorded as hot blanching area B4;

[0083] The area where the blanching area A3 and the blanching area B4 are located does not overlap with the orthographic projection area of ​​the positive electrode ear 1 and the negative electrode ear 2 on the diaphragm; the heights of the blanching area A3 and the blanching area B4 are both 0.5 mm; the blanching area B4 includes two sub-blanching areas arranged at intervals; the interval between adjacent sub-blanching areas is 0.05 mm.

[0084] Example 2

[0085] This embodiment provides a battery cell, specifically a laminated battery cell, wherein the battery cell includes 50 positive electrode sheets, 51 negative electrode sheets, and 103 separators arranged in a stacked manner, and a single separator is arranged between adjacent positive electrode sheets and negative electrode sheets;

[0086] like Figure 2 As shown, the positive electrode sheet has a positive electrode ear 1, and the negative electrode sheet has a negative electrode ear 2; the extension direction of the positive electrode ear 1 is parallel to the extension direction of the negative electrode ear 2, and the positive electrode ear 1 and the negative electrode ear 2 are located on opposite sides of the battery cell;

[0087] In the extension direction of the positive electrode ear 1 and the negative electrode ear 2, the two side edges of the diaphragm simultaneously exceed the two side edges of the positive electrode sheet and the negative electrode sheet, the total height of the area where the diaphragm exceeds the positive electrode sheet is 9 mm, and the total height of the area where the diaphragm exceeds the negative electrode sheet is 6 mm; the two opposite side areas where the diaphragm exceeds the positive electrode sheet and the negative electrode sheet are respectively recorded as the first area and the second area, the first area is the side close to the positive electrode ear 1, and the second area is the side close to the negative electrode ear 2; in the first area, a first hot blanching area and a fourth hot blanching area are arranged along the edge of the diaphragm, the first hot blanching area and the fourth hot blanching area are the same hot blanching area, recorded as hot blanching area A3; in the second area, a second hot blanching area and a third hot blanching area are arranged along the edge of the diaphragm, the second hot blanching area and the third hot blanching area are the same hot blanching area, recorded as hot blanching area B4;

[0088] The area where the blanching area A3 and the blanching area B4 are located does not overlap with the orthographic projection area of ​​the positive electrode tab 1 and the negative electrode tab 2 on the separator; the height of the blanching area A3 and the blanching area B4 are both 1 mm.

[0089] In summary, the utility model can prevent external particles from entering the battery cell and internal particles from overflowing by setting a hot zone on the diaphragm, and can also fix the pole pieces, reduce the risk of self-discharge and internal short circuit of the battery cell, improve the self-discharge performance and safety performance of the battery cell storage, and improve the energy density.

[0090] The above description is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technicians in the relevant technical field within the technical scope disclosed in the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A battery cell, characterized in that: The battery cell comprises a positive electrode sheet, a negative electrode sheet and a separator located between the positive electrode sheet and the negative electrode sheet; The positive electrode sheet has a positive electrode ear; in the extension direction of the positive electrode ear, both side edges of the diaphragm exceed the side edges of the positive electrode sheet; the diaphragm is provided with a first hot-scalding area and a second hot-scalding area in the two opposite side regions beyond the positive electrode sheet, respectively, and the area where the first hot-scalding area and the second hot-scalding area are located does not overlap with the orthographic projection area of ​​the positive electrode ear on the diaphragm; The negative electrode sheet has a negative electrode ear; in the extension direction of the negative electrode ear, both side edges of the diaphragm exceed the side edges of the negative electrode sheet; the diaphragm is respectively provided with a third hot-scalding area and a fourth hot-scalding area in the opposite side areas beyond the negative electrode sheet, and the area where the third hot-scalding area and the fourth hot-scalding area are located does not overlap with the positive projection area of ​​the negative electrode ear on the diaphragm.

2. The battery cell according to claim 1, characterized in that: The total height of the separator beyond the positive electrode sheet is 8.5 to 9 mm; The first blanching zone and the second blanching zone are both arranged along the edge of the diaphragm; The heights of the first blanching zone and the second blanching zone are independently 0.5 to 1 mm.

3. The battery cell according to claim 1, characterized in that: The total height of the separator beyond the negative electrode sheet is 5.5 to 6 mm; The third blanching zone and the fourth blanching zone are both arranged along the edge of the diaphragm; The heights of the third blanching zone and the fourth blanching zone are independently 0.5 to 1 mm.

4. The battery cell according to claim 1, characterized in that: The extension direction of the positive electrode tab is parallel to the extension direction of the negative electrode tab.

5. The battery cell according to claim 4, characterized in that: The first blanching zone and the third blanching zone are the same blanching zone, and the second blanching zone and the fourth blanching zone are the same blanching zone; Alternatively, the first blanching zone and the fourth blanching zone are the same blanching zone, and the second blanching zone and the third blanching zone are the same blanching zone.

6. The battery cell according to claim 5, characterized in that: The positive electrode tab and the negative electrode tab are located on the same side of the battery cell.

7. The battery cell according to claim 6, characterized in that: The blanching area on one side away from the positive electrode ear and the negative electrode ear includes a plurality of sub-blanching areas arranged at intervals; The interval between adjacent sub-scalding zones is 0.05-5 mm.

8. The battery cell according to claim 5, characterized in that: The positive electrode tab and the negative electrode tab are located on opposite sides of the battery cell.

9. The battery cell according to claim 1, characterized in that: The battery cell is a wound battery cell or a laminated battery cell; the battery cell comprises a plurality of positive electrode sheets, a plurality of negative electrode sheets and a plurality of separators, and a single separator is arranged between adjacent positive electrode sheets and negative electrode sheets.

10. A secondary battery, characterized in that: The secondary battery comprises the battery cell according to any one of claims 1 to 9.

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