Battery cell and battery module

Abstract

A battery cell and a battery module, wherein the battery cell comprises a casing and an electrode assembly accommodated in the casing. The electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet which are arranged in a stacked manner. The separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound together to form the electrode assembly. The negative electrode sheet comprises: a negative electrode substrate; a negative electrode active material layer covering the negative electrode substrate; and a negative electrode tab extending in a first direction and connected to the negative electrode substrate. The battery cell satisfies that: 2.702≤2H1-2T1×n-(T2-T3)≤19.958. The cycle life of the battery cell is prolonged, thereby improving the overall performance of the battery cell.

Description

Single cells and battery modules

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 5, 2023, with application number 202311138884.2 and application name “Single Cell and Battery Module”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to, but are not limited to, the field of battery technology, and specifically to a single cell and a battery module. Background Art

[0003] With the rapid development of mobile phones, laptops, electric vehicles, power tools, etc., lithium-ion batteries with high energy density, long cycle life and high safety performance have been widely used and developed. There is an urgent demand for lithium-ion batteries with larger capacity, greater durability and longer battery life. Technical issues

[0004] The present application provides a single cell battery and a battery module to increase the cycle life and thereby improve the overall performance of the single cell battery. Technical Solutions

[0005] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0006] In a first aspect, a single cell battery is provided, having a first orientation, comprising: a housing;

[0007] an electrode assembly, housed in the housing;

[0008] The electrode assembly comprises: a positive electrode sheet, a separator and a negative electrode sheet which are stacked, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound together to form the electrode assembly;

[0009] The negative electrode plate comprises:

[0010] negative electrode substrate;

[0011] A negative electrode active material layer, coated on the negative electrode substrate; and

[0012] a negative electrode tab extending along the first direction and connected to the negative electrode substrate;

[0013] Wherein, the single cell satisfies: 2.702≤2H1-2T1×n-(T2-T3)≤19.958;

[0014] H1mm is the length of the negative electrode tab in the first direction, T1mm is the thickness of the separator, n is the number of empty coils of the separator, T2mm is the total thickness of the negative electrode substrate and the negative electrode active material layer, and T3mm is the thickness of the negative electrode substrate.

[0015] Optionally, the single cell further satisfies: 7.5045≤2H1-2T1×n-(T2-T3)≤11.818.

[0016] Optionally, the length H1mm of the negative electrode tab in the first direction further satisfies: 2≤H1≤10;

[0017] Optionally, the length H1 mm of the negative electrode tab in the first direction further satisfies: 4≤H1≤6.

[0018] Optionally, the positive electrode plate includes: a positive electrode substrate;

[0019] a positive electrode active material layer, coated on the positive electrode substrate; and

[0020] a positive electrode tab extending along the first direction and connected to the positive electrode substrate;

[0021] The single cell satisfies: 1.622≤2H2-2T1×(n+2)-2T2-(T4-T5)≤19.844;

[0022] Wherein, H2mm is the length of the positive electrode tab in the first direction, T4mm is the total thickness of the positive electrode substrate and the positive electrode active material layer, and T5mm is the thickness of the positive electrode substrate.

[0023] Optionally, the single cell further satisfies: 7.05≤2H2-2T1×(n+2)-2T2-(T4-T5)≤11.589.

[0024] Optionally, the length H2mm of the positive electrode tab in the first direction satisfies: 2≤H2≤10;

[0025] Optionally, the length H2mm of the positive electrode tab in the first direction also satisfies: 4≤H2≤6.

[0026] Optionally, the thickness T1mm of the diaphragm satisfies: 0.006≤T1≤0.02;

[0027] Optionally, the thickness T1mm of the diaphragm satisfies: 0.009≤T1≤0.015.

[0028] Optionally, the number n of empty coils of the diaphragm satisfies: 0<n≤20;

[0029] Optionally, the number n of empty coils of the diaphragm satisfies: 5≤n≤10.

[0030] Optionally, the total thickness T2 mm of the negative electrode substrate and the negative electrode active material layer satisfies: 0.05≤T2≤0.5.

[0031] Optionally, the thickness T3mm of the negative electrode substrate satisfies: 0.002≤T3≤0.02.

[0032] Optionally, the total thickness T2 mm of the negative electrode substrate and the negative electrode active material layer satisfies: 0.1≤T2≤0.2.

[0033] Optionally, the thickness T3mm of the negative electrode substrate satisfies: 0.0045≤T3≤0.008.

[0034] Optionally, the total thickness T4 mm of the positive electrode substrate and the positive electrode active material layer satisfies: 0.05≤T4≤0.5.

[0035] Optionally, the thickness T5mm of the positive electrode substrate satisfies: 0.002≤T5≤0.03.

[0036] Optionally, the total thickness T4 mm of the positive electrode substrate and the positive electrode active material layer satisfies: 0.1≤T4≤0.2.

[0037] Optionally, the thickness T5mm of the positive electrode substrate satisfies: 0.01≤T5≤0.015.

[0038] Optionally, when the positive electrode sheet is unfolded, the positive electrode sheet has a second direction intersecting with the first direction, and the size of the positive electrode tab in the second direction is L1 mm, satisfying: 1≤L1≤10; and / or,

[0039] In the second direction, the distance between two adjacent positive electrode tabs is W1 mm, satisfying: 0<W1≤5; and / or;

[0040] The positive electrode tab has an axis, and the included angle between the axis of the positive electrode tab and the second direction is α1, satisfying: 0<α1≤90°.

[0041] Optionally, when the negative electrode tab is unfolded, the negative electrode tab has a second direction intersecting with the first direction, and a dimension of the negative electrode tab in the second direction is L2 mm, satisfying: 1≤L2≤10; and / or,

[0042] In the second direction, the distance between two adjacent negative electrode tabs is W2 mm, satisfying: 0<W2≤5; and / or;

[0043] The negative electrode tab has an axis, and an included angle between the axis of the negative electrode tab and the second direction is α2, satisfying: 0<α2≤90°.

[0044] Optionally, the dimension L1mm of the positive electrode tab in the second direction satisfies: 3≤L1≤5; and / or,

[0045] In the second direction, the spacing W1mm between two adjacent positive electrode tabs satisfies: 0<W1≤2; and / or;

[0046] An included angle α between the axis of the positive electrode tab and the second direction satisfies: 30°≤α1≤60°.

[0047] Optionally, the dimension L2mm of the negative electrode tab in the second direction satisfies: 3≤L2≤5; and / or,

[0048] In the second direction, the spacing W2 mm between two adjacent negative electrode tabs satisfies: 0<W2≤2; and / or;

[0049] An included angle α2 between the axis of the negative electrode tab and the second direction satisfies: 30°≤α2≤60°.

[0050] On the other hand, a battery module is further disclosed, comprising a housing; and a single cell as described in any one of the above items, wherein the single cell is housed in the housing. Beneficial effects

[0051] Compared with the prior art, the single cell in the present application satisfies: 2.702≤2H1-2T1×n-(T2-T3)≤19.958. By designing the length of the negative electrode tab, the thickness of the diaphragm and the number of empty coils, the thickness of the negative electrode sheet and the thickness of the negative electrode substrate in the single cell, the cycle life of the single cell is improved, thereby improving the overall performance of the single cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG1 is a cross-sectional view of a single cell provided according to an embodiment of the present application;

[0053] FIG2 is a schematic structural diagram of a positive electrode sheet provided according to an embodiment of the present application;

[0054] FIG3 is a schematic structural diagram of a negative electrode plate provided according to an embodiment of the present application.

[0055] Explanation of the reference numerals: 100, single cell; 110, negative electrode plate; 111, negative electrode substrate; 112, negative electrode active material layer; 113, negative electrode tab; 120, positive electrode plate; 121, positive electrode substrate; 122, positive electrode active material layer; 123, positive electrode tab; 130, separator.

[0056] Implementation Methods of the Application

[0057] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. The described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0058] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0059] Currently, existing lithium-ion batteries are typically composed of components such as positive electrodes, negative electrodes, and separators. The performance of lithium-ion batteries is closely related to these components. For example, parameters such as the thickness of the positive electrode sheet, the thickness of the negative electrode sheet, and the thickness of the separator all affect the performance of lithium-ion batteries. How to improve the cycle life of lithium-ion batteries based on components such as the positive electrode sheet, the negative electrode sheet, and the separator, and thus enhance the overall performance of lithium-ion batteries, has become an urgent problem to be solved.

[0060] In order to improve the above problems, this application designs the length of the negative electrode tab, the thickness of the diaphragm and the number of empty coils, the thickness of the negative electrode sheet and the thickness of the negative electrode substrate in the single cell to increase the cycle life of the single cell and thus improve the overall performance of the single cell.

[0061] In an embodiment of the present application, referring to FIG. 1 to FIG. 3 , the present application provides a single cell 100 .

[0062] The above-mentioned single cell 100 can be a secondary battery or a primary battery, and can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The single cell 100 can be cylindrical, flat, rectangular or other shapes.

[0063] Specifically, the single cell 100 has an intersecting first direction Z and a third direction Y, and the single cell 100 includes: a shell; and an electrode assembly, housed in the shell; the electrode assembly includes: a stacked positive electrode sheet 120, a separator 130 and a negative electrode sheet 110, the separator 130 is arranged between the positive electrode sheet 120 and the negative electrode sheet 110, and the positive electrode sheet 120, the negative electrode sheet 110 and the separator 130 are wound to form the electrode assembly; the above-mentioned negative electrode sheet 110 includes: a negative electrode substrate 111; a negative electrode active material layer 112, coated on the negative electrode substrate 111; and a negative electrode tab 113, extending along the first direction Z and connected to the negative electrode substrate 111; the above-mentioned single cell 100 satisfies: 2.702≤2H1-2T1×n-(T2-T3)≤19.958. That is, 2H1-2T1×n-(T2-T3) can be controlled within the range of 2.702 to 19.958. For example, 2H1-2T1×n-(T2-T3) can be a range consisting of one of 2.702, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 19.958, or any two of them. It is worth noting that the above specific values ​​of 2H1-2T1×n-(T2-T3) are given for illustrative purposes only, and any value within the range of 2.702 to 19.958 is within the scope of protection of this application. Where H1mm is the length of the negative electrode tab 113 in the first direction Z; T1mm is the thickness of the separator 130, and optionally, T1mm is the thickness of the separator 130 in the third direction Y; and n is the number of empty turns of the separator 130, where the empty turns are the number of turns in which only multiple layers of separator are stacked during the initial winding of the electrode assembly. The number of empty turns of the separator 130, n, can be determined by directly observing the wound electrode assembly. Alternatively, the wound electrode assembly can be laid out flat, with only the separator sandwiched between two adjacent layers of negative electrode sheets. The number of empty turns, n, is calculated as the number of separator layers sandwiched between the two layers of negative electrode sheets. It should be noted that if the number of empty turns is less than one, it is counted as one.

[0064] T2mm is the total thickness of the negative electrode substrate 111 and the negative electrode active material layer 112. Optionally, T2mm is the total thickness of the negative electrode substrate 111 and the negative electrode active material layer 112 in the third direction Y. T3mm is the thickness of the negative electrode substrate 111. Optionally, T3mm is the thickness of the negative electrode substrate 111 in the third direction Y.

[0065] It can be understood that in this application, the single cell is controlled to meet the following conditions: 2.702≤2H1-2T1×n-(T2-T3)≤19.958. By designing the length of the negative electrode tab, the thickness of the diaphragm and the number of empty coils, the thickness of the negative electrode plate and the thickness of the negative electrode substrate in the single cell, the tab height is ensured to be smaller when the tab is flattened in different single cells, thereby reducing the stacking height of the tab and increasing the height of the portion of the negative electrode plate 110 having the negative active material layer 112, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the overall performance of the single cell.

[0066] Optionally, the above-mentioned single cell 100 further satisfies the following: 7.5045 ≤ 2H1-2T1×n-(T2-T3) ≤ 11.818. That is, 2H1-2T1×n-(T2-T3) can be controlled within the range of 7.5045 to 11.818. For example, 2H1-2T1×n-(T2-T3) can be in the range of 7.5045, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, and 11.818, or any two thereof. It is worth noting that the above-mentioned specific values ​​of 2H1-2T1×n-(T2-T3) are given for example only, and any value within the range of 7.5045 to 11.818 is within the scope of protection of this application.

[0067] In one embodiment, the length H1mm of the negative electrode tab 113 in the first direction Z satisfies the following relationship: 2≤H1≤10. That is, the length H1mm of the negative electrode tab 113 in the first direction Z can be controlled within a range of 2 to 10mm. For example, the length H1mm of the negative electrode tab 113 in the first direction Z can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, or 10mm, or a range consisting of any two of these. It is worth noting that the specific values ​​for the length H1 are provided for illustrative purposes only; any value within the range of 2mm to 10mm is within the scope of this application. Setting the height of the negative electrode tab 113 within a range of 2mm to 10mm ensures weld strength between the negative electrode tab and the current collector plate while also increasing the energy density of the single cell.

[0068] In one embodiment, the length H1mm of the negative electrode tab 113 in the first direction Z further satisfies the following relationship: 4≤H1≤6. That is, the length H1mm of the negative electrode tab 113 in the first direction Z can be controlled within the range of 4 to 6mm. For example, the length H1mm of the negative electrode tab 113 in the first direction Z can be 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm, or 6mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the length H1 are given for illustrative purposes only, and any value within the range of 4mm to 6mm is within the scope of protection of this application.

[0069] The length H1 of the negative electrode tab 113 in the first direction Z can be measured directly when the negative electrode sheet 110 is in a wound state, or the negative electrode sheet 110 can be unfolded from the wound state to a flat state for measurement. Optionally, in this application, the negative electrode sheet 110 is first unfolded, and the unfolded positive electrode sheet 120 is flattened into a flat state. The length H1 of the negative electrode tab 113 at different positions in the first direction Z is measured multiple times using a measuring tool, and the average value is calculated. The measuring tool can be either a ruler or a vernier caliper.

[0070] It can be understood that in the present application, the length H1mm of the negative electrode tab 113 in the first direction Z is controlled within the range of 4 to 6mm to ensure that the height of the negative electrode tab is minimized when the tab is flattened, thereby reducing the stacking height of the negative electrode tab, increasing the height of the portion of the negative electrode sheet having the negative electrode active material layer, improving the energy density and cycle life of the single cell, and thereby improving the overall performance of the single cell.

[0071] In one embodiment, the positive electrode sheet 120 includes: a positive electrode substrate 121; a positive electrode active material layer 122 coated on the positive electrode substrate 121; and a positive electrode tab 123 connected to the positive electrode substrate 121;

[0072] Specifically, the above-mentioned single cell 100 further satisfies the following condition: 1.622≤2H2-2T1×(n+2)-2T2-(T4-T5)≤19.844; that is, 2H2-2T1×(n+2)-2T2-(T4-T5) can be controlled within the range of 1.622 to 19.844. For example, 2H2-2T1×(n+2)-2T2-(T4-T5) can be in the range of one of 1.622, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 19.844, or any two of these. It is worth noting that the above specific numerical values ​​of 2H2-2T1×(n+2)-2T2-(T4-T5) are given for example only, and any value within the range of 1.622 to 19.844 is within the protection scope of this application.

[0073] Among them, T4mm is the total thickness of the positive electrode substrate 121 and the positive electrode active material layer 122, optionally, T4mm is the total thickness of the positive electrode substrate 121 and the positive electrode active material layer 122 in the third direction Y; T5mm is the thickness of the positive electrode substrate 121, optionally, T5mm is the thickness of the positive electrode substrate 121 in the third direction Y.

[0074] Among them, the parameters T1, n, and T2 have been explained in the previous text. Since the above parameters have been described in detail in the previous text, this application will not provide corresponding descriptions. Please refer to the previous description.

[0075] It can be understood that in this application, by limiting the single cell to satisfy: 1.622≤2H2-2T1×(n+2)-2T2-(T4-T5)≤19.844, the length of the positive electrode tab, the thickness of the diaphragm and the number of empty coils, the thickness of the negative electrode sheet, the thickness of the positive electrode sheet and the thickness of the positive electrode substrate in the single cell are designed to ensure that the tab height is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the tab and increasing the height of the portion of the positive electrode sheet 120 having the positive active material layer 122, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the overall performance of the single cell.

[0076] Optionally, the above-mentioned single cell 100 further satisfies the following: 7.05≤2H2-2T1×(n+2)-2T2-(T4-T5)≤11.589. That is, 2H2-2T1×(n+2)-2T2-(T4-T5) can be controlled within the range of 7.05 to 11.589. For example, 2H2-2T1×(n+2)-2T2-(T4-T5) can be in the range of one of 7.05, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, and 11.589, or any two thereof. It is worth noting that the above-mentioned specific numerical values ​​of 2H2-2T1×(n+2)-2T2-(T4-T5) are given for example only, and any value within the range of 7.05 to 11.589 is within the scope of protection of this application.

[0077] In one embodiment, the length H2mm of the positive electrode tab 123 in the first direction Z further satisfies: 2≤H2≤10. That is, the length H2mm of the positive electrode tab 123 in the first direction Z can be controlled within the range of 2 to 10mm. For example, the length H2mm of the positive electrode tab 123 in the first direction Z can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, or 10mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the length H2mm are given for example only, and any value within the range of 2mm to 10mm is within the scope of protection of this application.

[0078] Preferably, the length H2mm of the positive electrode tab 123 in the first direction Z also satisfies: 4≤H2≤6. That is, the length H2mm of the positive electrode tab 123 in the first direction Z can be controlled within the range of 4 to 6mm. For example, the length H2mm of the positive electrode tab 123 in the first direction Z can be 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm, 6mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific numerical values ​​of the length H2mm are given for example only, and any value within the range of 4 to 6mm is within the scope of protection of this application.

[0079] The length H2 of the positive electrode tab 123 in the first direction Z can be measured directly when the positive electrode sheet 120 is in a coiled state, or the positive electrode sheet 120 can be unrolled from the coiled state and measured flat. Optionally, in this application, the length H2 of the positive electrode tab 123 in the first direction Z is measured multiple times at different locations using a measuring tool, and the average value is calculated. The measuring tool can be either a ruler or a vernier caliper.

[0080] It can be understood that in the present application, the length H2mm of the positive electrode tab 123 in the first direction Z is controlled within the range of 4 to 6mm to ensure that the height of the positive electrode tab is minimized when the tab is flattened, thereby reducing the stacking height of the positive electrode tab and increasing the height of the portion of the positive electrode active material layer on the positive electrode sheet to improve the cycle life of the single cell, while increasing the energy density of the single cell, thereby improving the overall performance of the single cell.

[0081] In one embodiment, the thickness T1mm of the diaphragm 130 satisfies the following condition: 0.006 ≤ T1 ≤ 0.02. That is, the thickness T1mm of the diaphragm 130 can be controlled within the range of 0.006 mm to 0.02 mm. For example, the thickness T1mm of the diaphragm 130 can be one of 0.006 mm, 0.008 mm, 0.01 mm, 0.012 mm, 0.014 mm, 0.016 mm, 0.018 mm, and 0.02 mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the thickness T1mm are provided for illustrative purposes only, and any value within the range of 0.006 mm to 0.02 mm is within the scope of protection of this application.

[0082] In some embodiments, the thickness T1mm of the diaphragm 130 satisfies the following condition: 0.009≤T1≤0.015. That is, the thickness T1mm of the diaphragm 130 can be controlled within the range of 0.009mm to 0.015mm. For example, the thickness T1mm of the diaphragm 130 can be one of 0.009mm, 0.01mm, 0.011mm, 0.012mm, 0.013mm, 0.014mm, 0.015mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the thickness T1 are given for illustrative purposes only, and any value within the range of 0.009mm to 0.015mm is within the scope of protection of this application.

[0083] Among them, the thickness T1mm of the diaphragm 130 can be obtained by unfolding the diaphragm 130 into a flat state, and then measuring the thickness of different positions of the diaphragm 130 multiple times with a measuring tool and calculating the average value. The measuring tool can be any one of a thickness gauge and a micrometer. It can be understood that in this application, by controlling the thickness T1mm of the diaphragm 130 within the range of 0.009mm to 0.015mm, the thickness of the diaphragm 130 is controlled within a reasonable range, so as to ensure that the height of the positive electrode tab and the negative electrode tab is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the positive electrode tab and the negative electrode tab, and increasing the height of the portion of the positive electrode active material layer on the positive electrode sheet and the portion of the negative electrode sheet with the negative electrode active material layer, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the overall performance of the single cell.

[0084] In one embodiment, the number of unwound turns n of the diaphragm 130 satisfies the following condition: 0 < n ≤ 20. That is, the number of unwound turns n of the diaphragm 130 can be controlled within the range of 0 to 20 turns. For example, the number of unwound turns n of the diaphragm 130 can be 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 turns, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​for the number of unwound turns n are provided for illustrative purposes only; any value within the range of 0 to 20 turns is within the scope of protection of this application.

[0085] In a preferred embodiment, the number of unwound turns n of the diaphragm 130 satisfies the following condition: 5 ≤ n ≤ 10. That is, the number of unwound turns n of the diaphragm 130 can be controlled within the range of 5 to 10 turns. For example, the number of unwound turns n of the diaphragm 130 can be 5, 6, 7, 8, 9, or 10 turns, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​for the number of unwound turns n are provided for illustrative purposes only; any value within the range of 5 to 10 turns is within the scope of protection of this application.

[0086] It can be understood that in the present application, the number of empty winding turns n of the diaphragm 130 is controlled within the range of 5 to 10 turns, so as to control the number of empty winding turns of the diaphragm 130 within a reasonable range, so as to ensure that the height of the positive electrode tab and the negative electrode tab is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the positive electrode tab and the negative electrode tab, and increasing the height of the part with the positive electrode active material layer on the positive electrode sheet and the part with the negative electrode active material layer on the negative electrode sheet, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the comprehensive performance of the single cell.

[0087] Optionally, the material of the diaphragm 130 includes, but is not limited to, any one of PP material, PE material or PP / PE composite material.

[0088] The surface of the diaphragm 130 may be provided with an adhesive layer, which includes but is not limited to a PVDF layer.

[0089] The surface of the diaphragm 130 may be provided with a safety coating. The material of the safety coating includes, but is not limited to, boehmite and aluminum oxide. The above materials may be used alone or in any combination.

[0090] In one embodiment, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 satisfies: 0.05≤T2≤0.5. That is, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 can be controlled within the range of 0.05mm to 0.5mm. For example, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 can be one of 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific numerical values ​​of the total thickness T2mm are given for example only, and any value within the range of 0.05 to 0.5mm is within the scope of protection of this application.

[0091] In one embodiment, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 satisfies: 0.1≤T2≤0.2. That is, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 can be controlled within the range of 0.1mm to 0.2mm. For example, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 can be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the total thickness T2mm are given for example only, and any value within the range of 0.1 to 0.2mm is within the scope of protection of this application.

[0092] The total thickness T2 mm of the negative electrode substrate 111 and the negative electrode active material layer 112 can be obtained by first unfolding the negative electrode sheet 110 into a flat state, then measuring the total thickness of the negative electrode substrate 111 and the negative electrode active material layer 112 at different positions on the negative electrode sheet 110 multiple times using a measuring tool, and calculating the average value. The measuring tool can be either a thickness gauge or a micrometer.

[0093] It can be understood that in the present application, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is controlled within the range of 0.1mm to 0.2mm, so as to control the thickness of the negative electrode substrate 111 and the negative electrode active material layer 112 within a reasonable range, so as to ensure that the height of the positive electrode tab and the negative electrode tab is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the positive electrode tab and the negative electrode tab, and increasing the height of the part with the positive electrode active material layer on the positive electrode sheet and the part with the negative electrode active material layer on the negative electrode sheet, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the comprehensive performance of the single cell.

[0094] In the embodiment of the present application, the thickness T3mm of the negative electrode substrate 111 satisfies: 0.002≤T≤0.02. That is, the thickness T3mm of the negative electrode substrate 111 can be controlled within the range of 0.002mm to 0.02mm. For example, the thickness T3mm of the negative electrode substrate 111 can be one of 0.002mm, 0.006mm, 0.01mm, 0.011mm, 0.016mm, 0.018mm, 0.02mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific numerical values ​​of the thickness T3mm are only given as examples, and any value within the range of 0.002mm to 0.02mm is within the protection scope of the present application.

[0095] In one embodiment, the thickness T3mm of the negative electrode substrate 111 satisfies: 0.0045≤T3≤0.008. That is, the thickness T3mm of the negative electrode substrate 111 can be controlled within the range of 0.0045mm to 0.008mm. For example, the thickness T3mm of the negative electrode substrate 111 can be one of 0.0045mm, 0.005mm, 0.0055mm, 0.006mm, 0.0065mm, 0.007mm, 0.0075mm, 0.008mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific numerical values ​​of the thickness T3mm are given for example only, and any value within the range of 0.0045mm to 0.008mm is within the protection scope of this application.

[0096] The thickness T3 mm of the negative electrode substrate 111 can be determined by first flattening the negative electrode sheet 110, removing the negative electrode active material layer 112 on the surface of the negative electrode sheet 110, and then measuring the thickness of the negative electrode substrate 111 at different locations multiple times using a measuring tool to calculate the average value. The measuring tool can be either a thickness gauge or a micrometer.

[0097] It can be understood that in the present application, the thickness T3mm of the negative electrode substrate 111 is controlled within the range of 0.0045mm to 0.008mm, so as to control the thickness of the negative electrode substrate 111 within a reasonable range, so as to ensure that the height of the negative electrode tab is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the negative electrode tab and increasing the height of the portion of the negative electrode sheet having the negative electrode active material layer, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the overall performance of the single cell.

[0098] Alternatively, in one embodiment, the negative electrode substrate 111 includes, but is not limited to, metal foil, a metal cylinder, a metal coil, a metal plate, a metal film, expanded metal, stamped metal, or foamed metal. In one embodiment, the negative electrode substrate 111 is a metal foil. In one embodiment, the negative electrode substrate 111 is a copper foil. As used herein, the term "copper foil" includes copper alloy foil.

[0099] The negative electrode active material layer 112 can be one or more layers, and each layer of the multiple layers can contain the same or different negative electrode active materials. In the embodiment of the present application, the charge capacity of the negative electrode active material is greater than the discharge capacity of the positive electrode active material to prevent lithium metal from being deposited on the negative electrode sheet during charging.

[0100] The negative electrode active material layer 112 includes, but is not limited to, artificial graphite, natural graphite, soft carbon, hard carbon, amorphous carbon, carbon fiber, carbon nanotubes, and mesophase carbon microspheres. The above negative electrode active materials can be used alone or in any combination.

[0101] The negative electrode sheet 110 in the single cell 100 of the present application can be prepared using any known method. For example, a conductive agent, a binder, an additive, and a solvent are added to the negative electrode active material to form a slurry, which is then coated on the negative electrode substrate and pressed after drying to form an electrode.

[0102] In one embodiment, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 satisfies the following: 0.05≤T4≤0.5; that is, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 can be controlled within the range of 0.05mm to 0.5mm. For example, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 can be one of 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the total thickness T4mm are given for example only, and any value within the range of 0.05mm to 0.5mm is within the scope of protection of this application.

[0103] In one embodiment, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 satisfies the following: 0.1≤T4≤0.2; that is, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 can be controlled within the range of 0.1mm to 0.2mm. For example, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 can be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.214mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the total thickness T4mm are given for example only, and any value within the range of 0.1mm to 0.2mm is within the scope of protection of this application.

[0104] The total thickness T4 mm of the positive electrode substrate 121 and the positive electrode active material layer 122 can be obtained by first unfolding the positive electrode sheet 120 into a flat state, measuring the total thickness of the positive electrode substrate 121 and the positive electrode active material layer 122 at different positions on the positive electrode sheet 120 multiple times using a measuring tool, and calculating the average value. The measuring tool can be either a thickness gauge or a micrometer.

[0105] It can be understood that in the present application, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is controlled within the range of 0.1mm to 0.2mm, so as to control the thickness of the positive electrode substrate 121 and the positive electrode active material layer 122 within a reasonable range, so as to ensure that the height of the positive electrode tab is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the positive electrode tab and increasing the height of the portion of the positive electrode sheet with the positive electrode active material layer, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the overall performance of the single cell.

[0106] In one embodiment, the thickness T5mm of the positive electrode substrate 121 satisfies: 0.002≤T5≤0.03. That is, the thickness T5mm of the positive electrode substrate 121 can be controlled within the range of 0.002mm to 0.03mm. For example, the thickness T5mm of the positive electrode substrate 121 can be one of 0.002mm, 0.006mm, 0.01mm, 0.014mm, 0.018mm, 0.022mm, 0.026mm, 0.03mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific numerical values ​​of the thickness T5mm are only given as examples, and any value within the range of 0.002mm to 0.03mm is within the protection scope of this application.

[0107] Preferably, the thickness T5mm of the positive electrode substrate 121 satisfies: 0.01≤T5≤0.015. That is, the thickness T5mm of the positive electrode substrate 121 can be controlled within the range of 0.01mm to 0.015mm. For example, the thickness T5mm of the positive electrode substrate 121 can be one of 0.01mm, 0.011mm, 0.012mm, 0.013mm, 0.014mm, 0.015mm, or a range consisting of any two of them. It is worth noting that the above-mentioned specific numerical values ​​of the thickness T5mm are only given as examples, and any value within the range of 0.002mm to 0.03mm is within the protection scope of this application.

[0108] The thickness T5 mm of the positive electrode substrate 121 can be obtained by first unfolding the positive electrode sheet 120 into a flat state, then completely removing the positive electrode active material layer 122 on the surface of the positive electrode sheet 120, leaving only the positive electrode substrate 121, and then measuring the thickness of the positive electrode substrate 121 at different locations multiple times using a measuring tool and calculating the average value. The measuring tool can be either a thickness gauge or a micrometer.

[0109] It can be understood that in the present application, the thickness T5mm of the positive electrode substrate 121 is controlled within the range of 0.01mm to 0.015mm, so as to control the thickness of the positive electrode substrate 121 within a reasonable range, so as to ensure that the height of the positive electrode tab is minimized when the tab is flattened in different single cells, thereby reducing the stacking height of the positive electrode tab and increasing the height of the portion of the positive electrode sheet having the positive electrode active material layer, so as to improve the cycle life of the single cell, while improving the energy density of the single cell, thereby improving the overall performance of the single cell.

[0110] In one embodiment, the positive electrode active material layer 122 may be provided in one or more layers, and each layer of the multiple layers may contain the same or different positive electrode active materials. The positive electrode active material is any substance that can reversibly insert and remove metal ions such as lithium ions.

[0111] The positive electrode active material layer 122 includes, but is not limited to, positive electrode active materials, including, but not limited to, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate (LFP), and ternary materials. Ternary materials include, but are not limited to, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

[0112] The positive electrode active material may further contain doping elements. The doping elements may include aluminum, magnesium, titanium, zirconium, strontium and the like, as long as they can make the structure of the positive electrode active material more stable.

[0113] The positive electrode active material may further include a coating element. The coating element may include aluminum, magnesium, titanium, zirconium, fluorine, boron and the like, as long as the coating element can make the structure of the positive electrode active material more stable.

[0114] Optionally, the type of the positive electrode substrate 121 in the present application is not particularly limited, and it can be any known material suitable for use as the positive electrode substrate 121 as long as it does not impair the effect of the present application.

[0115] Specifically, in one embodiment, the positive electrode substrate 121 may include, but is not limited to, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; or carbon materials such as carbon cloth and carbon paper. In one embodiment, the positive electrode substrate 121 is a metal material. In one embodiment, the positive electrode current collector is aluminum foil.

[0116] In one embodiment, the positive electrode sheet 120 further includes a positive electrode conductive agent and a positive electrode binder. The types of the positive electrode conductive agent and the positive electrode binder in the present application are not limited, and any known materials can be used as long as they do not impair the effects of the present application.

[0117] Specifically, the positive electrode conductive agent may include, but is not limited to, graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon materials such as amorphous carbon such as needle coke; carbon nanotubes; graphene, etc. The above positive electrode conductive materials may be used alone or in any combination.

[0118] The positive electrode binder includes, but is not limited to, polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose. The above positive electrode conductive materials can be used alone or in any combination.

[0119] The positive electrode sheet 120 in the single cell 100 of the present application can be prepared using any known method. For example, a conductive agent, a binder, and a solvent can be added to the positive electrode active material to form a slurry, which is then coated onto the positive electrode substrate and pressed after drying to form the electrode. Alternatively, the negative electrode active material can be roll-formed into a sheet electrode or compression-molded into a pellet electrode.

[0120] In one embodiment, when the pole piece is unfolded, the pole piece has a second direction X intersecting with the first direction Z. Specifically, when the pole piece is unfolded, the pole piece has a second direction X intersecting with the first direction Z and the third direction Y in pairs. The size of the pole ear in the second direction X is Lmm, satisfying: 1≤L≤10.

[0121] In one embodiment, when the pole piece is unfolded, the pole piece has a second direction X intersecting with the first direction Z. Specifically, when the pole piece is unfolded, the pole piece has a second direction X intersecting with the first direction Z and the third direction Y in pairs. The size of the pole ear in the second direction X is Lmm, satisfying: 3≤L≤5.

[0122] Specifically, the electrode piece can be a positive electrode piece or a negative electrode piece. When the electrode piece is a positive electrode piece, the electrode tab is a positive electrode tab. When the electrode piece is a negative electrode piece, the electrode tab is a negative electrode tab.

[0123] Referring to Figure 2 , when the positive electrode tab is unfolded and the tab is the positive electrode tab 123, the dimension of the positive electrode tab 123 in the second direction X is L1mm, satisfying the following: 1≤L1≤10; that is, the dimension L1mm of the positive electrode tab 123 in the second direction X can be controlled within the range of 1 to 10mm. For example, the dimension L1mm of the positive electrode tab 123 in the second direction X can be one of 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 9mm, and 10mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific numerical value of the dimension L1mm is given for example only, and any value within the range of 1 to 10mm is within the scope of protection of this application.

[0124] In one embodiment, the dimension L1mm of the positive electrode tab 123 in the second direction X satisfies the following conditions: 3≤L1≤5; that is, the dimension L1mm of the positive electrode tab 123 in the second direction X can be controlled within the range of 3 to 5mm. For example, the dimension L1mm of the positive electrode tab 123 in the second direction X can be 3mm, 3.5mm, 4mm, 4.5mm, or 5mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the dimension L1mm are provided for illustrative purposes only; any value within the range of 3 to 5mm is within the scope of protection of this application.

[0125] Referring to Figure 3 , when the negative electrode tab is unfolded and the tab is negative tab 113, the dimension of negative tab 113 in the second direction X is L2 mm, satisfying the following: 1 ≤ L2 ≤ 10; that is, the dimension L2 mm of negative tab 113 in the second direction X can be controlled within the range of 1 to 10 mm. For example, the length L2 mm of negative tab 113 in the second direction X can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 9 mm, or 10 mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of dimension L2 mm are provided for illustrative purposes only; any value within the range of 1 to 10 mm is within the scope of protection of this application.

[0126] In one embodiment, the dimension L2mm of the negative electrode tab 113 in the second direction X satisfies the following: 3≤L2≤5; that is, the dimension L2mm of the negative electrode tab 113 in the second direction X can be controlled within the range of 3mm to 5mm. For example, the dimension L2mm of the negative electrode tab 113 in the second direction X can be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the dimension L2mm are provided for illustrative purposes only; any value within the range of 3mm to 5mm is within the scope of protection of this application.

[0127] The size L1 mm of the positive electrode tab 123 in the second direction X and the size L2 mm of the negative electrode tab 113 in the second direction X can be the same or different, and this application does not impose any specific restrictions, as long as it does not affect the effect of this application. Optionally, the size L1 mm of the positive electrode tab 123 in the second direction X and the size L2 mm of the negative electrode tab 113 in the second direction X are the same.

[0128] The dimension L1 mm of the positive electrode tab 123 in the second direction X can be obtained by first flattening the positive electrode sheet 120 into a straight state, then measuring the length of the positive electrode tab 123 on the positive electrode sheet 120 in the second direction X multiple times using a measuring tool, and calculating the average value. The measuring tool can be either a ruler or a vernier caliper.

[0129] The dimension L2 mm of the negative electrode tab 113 in the second direction X can be obtained by first flattening the negative electrode sheet 110 into a straight state, then measuring the length of the negative electrode tab 113 on the negative electrode sheet 110 in the second direction X multiple times using a measuring tool, and calculating the average value. The measuring tool can be either a ruler or a vernier caliper.

[0130] It can be understood that in this application, the dimensions of the positive electrode tab and the negative electrode tab in the second direction X are controlled within the range of 3mm to 5mm to enhance the winding manufacturability of the positive electrode sheet and the negative electrode sheet, improve the winding quality rate, and at the same time reduce the welding difficulty between the current collecting plate and the tab in the single cell, thereby improving the welding quality rate.

[0131] In one embodiment, when the pole piece is unfolded, in the second direction X, the distance between two adjacent pole tabs is W mm, satisfying: 0<W≤5.

[0132] In one embodiment, when the pole piece is unfolded, in the second direction X, the distance W mm between two adjacent pole tabs satisfies: 0<W≤2.

[0133] Specifically, referring to Figure 2 , when the positive electrode tab is unfolded and the tab is the positive electrode tab 123, in the second direction X, the spacing between two adjacent positive electrode tabs 123 is W1mm, satisfying: 0<W1≤5; that is, the spacing W1mm between two adjacent positive electrode tabs 123 can be controlled within the range of 0mm to 5mm. For example, the spacing W1mm between two adjacent positive electrode tabs 123 can be one of 1mm, 2mm, 3mm, 4mm, 5mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific value of the spacing W1mm is given for example only, and any value within the range of 0mm to 5mm is within the scope of protection of this application.

[0134] In one embodiment, when the positive electrode sheet 120 is unfolded, the spacing between two adjacent positive electrode tabs 123 in the second direction X is W1mm, satisfying the following: 0<W1≤2; that is, the spacing W1mm between two adjacent positive electrode tabs 123 can be controlled within the range of 0mm to 2mm. For example, the spacing W1mm between two adjacent positive electrode tabs 123 can be one of 0.5mm, 1mm, 1.5mm, 2mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific value of the spacing W1mm is given for example only, and any value within the range of 0-2mm is within the scope of protection of this application.

[0135] Referring to Figure 3 , when the tabs are negative tabs 113, and when the negative electrode sheet 110 is unfolded, the spacing between two adjacent negative tabs 113 in the second direction X is W2mm, satisfying the following: 0<W2≤5; that is, the spacing W2mm between two adjacent negative tabs 113 can be controlled within the range of 0-5mm. For example, the spacing W2mm between two adjacent negative tabs 113 can be one of 1mm, 2mm, 3mm, 4mm, 5mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the spacing W2mm are provided for illustrative purposes only; any value within the range of 0mm to 5mm is within the scope of protection of this application.

[0136] In one embodiment, when the negative electrode tab 110 is in a straight state, the spacing between two adjacent negative electrode tabs 113 in the second direction X is W2 mm, satisfying the following: 0<W2≤2; that is, the spacing W2 mm between two adjacent negative electrode tabs 113 can be controlled within the range of 0 mm to 2 mm. For example, the spacing W2 mm between two adjacent negative electrode tabs 113 can be one of 0.5 mm, 1 mm, 1.5 mm, 2 mm, or a range consisting of any two of these. It is worth noting that the above-mentioned specific value of the spacing W2 mm is provided for illustrative purposes only; any value within the range of 0 mm to 2 mm is within the scope of protection of this application.

[0137] The spacing W1mm between two adjacent positive electrode tabs 123 and the spacing W2mm between two adjacent negative electrode tabs 113 can be the same or different, and this application does not impose any specific restrictions, as long as it does not affect the effectiveness of this application. Preferably, the spacing W1mm between two adjacent positive electrode tabs 123 in this application is the same as the spacing W2mm between two adjacent negative electrode tabs 113.

[0138] The distance W1 mm ​​between two adjacent positive electrode tabs 123 can be obtained by first flattening the positive electrode sheet 120 into a straight state, then measuring the distance between adjacent positive electrode tabs 123 at different positions on the positive electrode sheet multiple times with a measuring tool, and calculating the average value. The measuring tool can be either a ruler or a vernier caliper.

[0139] The distance W2 mm between two adjacent negative electrode tabs 113 can be obtained by first disassembling the single battery, unfolding the negative electrode tab 110, and flattening the unfolded negative electrode tab 110 into a straight state. The distance between adjacent negative electrode tabs 113 at different positions on the negative electrode tab is measured multiple times using a measuring tool, and the average value is calculated. The measuring tool can be either a ruler or a vernier caliper.

[0140] It can be understood that in this application, the spacing between two adjacent positive electrode tabs 123 and the spacing between two adjacent negative electrode tabs 113 are controlled within the range of 0 mm to 2 mm to enhance the winding manufacturability of the positive electrode sheets and the negative electrode sheets, improve the winding quality, and at the same time reduce the welding difficulty between the current collecting plate and the tabs in the single cell, thereby improving the welding quality.

[0141] In one embodiment, the angle α between the axis of the tab and the second direction X satisfies: 0<α≤90°. In one embodiment, the angle α between the axis of the tab and the second direction X satisfies: 30°≤α≤60°.

[0142] The tab can be either the positive electrode tab 123 or the negative electrode tab 113 .

[0143] Specifically, referring to Figure 2, when the tab is the positive tab 123, the angle between the axis of the positive tab 123 and the second direction X is α1, satisfying: 0<α1≤90°. That is, the angle α1 between the axis of the positive tab 123 and the second direction X can be controlled within the range of 0 to 90°. For example, the angle α1 between the axis of the positive tab 123 and the second direction X can be one of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the angle α1 are given for example only, and any value within the range of 0° to 90° is within the scope of protection of this application.

[0144] In one embodiment, the angle α1 between the axis of the positive electrode tab 123 and the second direction X satisfies: 30°≤α1≤60°. That is, the angle α1 between the axis of the positive electrode tab 123 and the second direction X can be controlled within the range of 30° to 60°. For example, the angle α1 between the axis of the positive electrode tab 123 and the second direction X can be one of 30°, 35°, 40°, 45°, 50°, 55°, 60°, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the angle α1 are given for example only, and any value within the range of 30° to 60° is within the scope of protection of this application.

[0145] Referring to Figure 3 , when the tab is a negative electrode tab 113, the angle α2 between the axis of the negative electrode tab 113 and the second direction X satisfies: 0 < α2 ≤ 90°. That is, the angle α2 between the axis of the negative electrode tab 113 and the second direction X can be controlled within the range of 0 to 90°. For example, the angle α2 between the axis of the negative electrode tab 113 and the second direction X can be one of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, or a range consisting of any two of these. It is worth noting that the above-mentioned specific values ​​of the angle α2 are given for illustrative purposes only, and any value within the range of 0° to 90° is within the scope of protection of this application.

[0146] In one embodiment, the angle α2 between the axis of the negative electrode tab 113 and the second direction X satisfies: 30°≤α2≤60°. That is, the angle α2 between the axis of the negative electrode tab 113 and the second direction X can be controlled within the range of 30° to 60°. For example, the angle α2 between the axis of the negative electrode tab 113 and the second direction X can be one of 30°, 35°, 40°, 45°, 50°, 55°, 60°, or a range consisting of any two of them. It is worth noting that the above-mentioned specific values ​​of the angle α2 are given for illustrative purposes only, and any value within the range of 30° to 60° is within the scope of protection of this application.

[0147] The angle α1 between the axis of the positive electrode tab 123 and the second direction X and the angle α2 between the axis of the negative electrode tab 113 and the second direction X can be the same or different. This application does not impose any specific restrictions, as long as it does not affect the effect of this application. In some embodiments, the angle α1 between the axis of the positive electrode tab 123 and the second direction X and the angle α2 between the axis of the negative electrode tab 113 and the second direction X in this application are the same.

[0148] 3 , when the positive electrode sheet 120 is unfolded, the axis of the positive electrode tab 123 refers to the central axis of the positive electrode tab 123 along its extending direction.

[0149] 2 , when the negative electrode tab 110 is unfolded, the axis of the negative electrode tab 113 refers to the central axis of the negative electrode tab 113 along its extending direction.

[0150] Among them, the central axis of the positive electrode tab 123 can be determined by first unfolding the positive electrode sheet and the positive electrode tab, and flattening the unfolded positive electrode sheet into a flat state, and then determining the central axis set along the extension direction of the positive electrode tab as the axis of the positive electrode tab; the central axis of the negative electrode tab 113 can be determined by first disassembling the single battery, unfolding the negative electrode sheet, and flattening the unfolded negative electrode sheet into a flat state, and then determining the central axis set along the extension direction of the negative electrode tab as the axis of the negative electrode tab.

[0151] The angle α1 between the axis of the positive electrode tab 123 and the second direction X can be obtained by first disassembling the single battery, unfolding the positive electrode sheet 120, and flattening the unfolded positive electrode sheet 120 into a straight state. Then, the angle between the axis of the positive electrode tab 123 on the positive electrode sheet and the second direction X is measured multiple times using a measuring tool and the average value is calculated. The measuring tool can be an angle measuring instrument.

[0152] The angle α2 between the axis of the negative electrode tab 113 and the second direction X can be obtained by first unfolding the negative electrode sheet 110, flattening the unfolded negative electrode sheet 110 into a straight state, and then measuring the angle between the axis of the negative electrode tab 113 on the negative electrode sheet and the second direction X multiple times using a measuring tool and calculating the average value. The measuring tool can be an angle measuring instrument.

[0153] It can be understood that in the present application, the angle between the axis of the negative electrode tab 113 and the second direction X and the angle between the axis of the positive electrode tab 123 and the second direction X are controlled within the range of 30° to 60°, thereby enhancing the winding manufacturability and improving the winding quality. At the same time, the flattened plane of the tab is further optimized, thereby improving the welding yield between the end face of the tab and the current collecting disk in subsequent processes and improving the welding effect between the tab and the current collecting disk.

[0154] In a preferred embodiment of the present application, the single cell 100 further comprises an electrolyte contained in the housing, and the electrolyte infiltrates the electrode assembly. The electrolyte used in the single cell 100 of the present application comprises an electrolyte and a solvent for dissolving the electrolyte.

[0155] In some embodiments of the present application, the single cell 100 is a cylindrical single cell.

[0156] The electrolyte is not particularly limited in this application, and any known electrolyte may be used as long as it does not impair the effectiveness of this application. In the case of a secondary battery, a lithium salt is generally used. In one embodiment, the electrolyte includes, but is not limited to, LiPF6.

[0157] Meanwhile, there is no particular limitation on the electrolyte content in the present application, as long as it does not impair the effects of the present application, and can be, for example, 0.8 mol / L to 2.2 mol / L.

[0158] In the present application, there is no particular limitation on the solvent, and any known solvent may be used as long as the effects of the present application are not impaired.

[0159] In one embodiment, the solvent includes, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), butylene carbonate (BC), and methyl ethylene carbonate (MEC). The above solvents can be used alone or in any combination.

[0160] On the other hand, in an embodiment of the present application, the present application further provides a battery module, comprising: a containing box; and a single cell as described in any one of the above items, wherein the single cell of the battery module is housed in the containing box.

[0161] Specifically, the battery module may be a battery module or a battery pack.

[0162] On the other hand, in an embodiment of the present application, the present application further provides an electrical device, including the battery module described above, which serves as a power supply for the electrical device. The electrical device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0163] The preparation of lithium-ion batteries is described below using lithium-ion batteries as an example and in combination with specific embodiments. Those skilled in the art will understand that the preparation method described in this application is only an embodiment, and any other suitable preparation method is within the scope of this application.

[0164] The following describes the performance evaluation of the lithium-ion battery according to the embodiments and comparative examples of the present application.

[0165] Example 1

[0166] This embodiment provides a preparation of a lithium ion battery, and the specific process is as follows:

[0167] 1. Preparation of positive electrode sheet

[0168] The positive electrode active material is lithium iron phosphate, the conductive agent is conductive carbon black SP, and the binder is PVDF in a mass ratio of 97:0.7:2.3, and then NMP is added as a solvent for mixing. After stirring for a certain time, a uniform positive electrode slurry with a certain fluidity is obtained; the positive electrode slurry is evenly coated on both sides of the positive electrode current collector carbon-coated aluminum foil, and then transferred to a 120°C oven for drying, and then rolled, slit, and cut into pieces to obtain the positive electrode sheet.

[0169] 2. Preparation of negative electrode sheet

[0170] The negative electrode active material graphite, the conductive agent conductive carbon black SP, the thickener CMC, and the binder SBR are mixed in a mass ratio of 96.5:0.5:1.2:1.8, and then deionized water is added as a solvent for mixing. After stirring for a certain period of time, a uniform negative electrode slurry with a certain fluidity is obtained; the negative electrode slurry is evenly coated on both sides of the negative electrode current collector copper foil, and then transferred to a 110°C oven for drying, and then rolled, slit, and cut into pieces to obtain the negative electrode sheet.

[0171] 3. Preparation of electrolyte

[0172] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, 1 mol / L LiPF6 was added and mixed evenly, and then 1% vinylene carbonate was added to prepare an electrolyte.

[0173] 4. Preparation of diaphragm

[0174] PP film is used as the separator.

[0175] 5. Preparation of lithium-ion batteries

[0176] The negative electrode sheet and the positive electrode sheet prepared by the above steps are dried and then used together with the separator to prepare a wound electrode assembly using a winding machine. The positive electrode tab and the negative electrode tab are welded to the top cover, and the welded electrode assembly with the top cover is placed in an aluminum shell for packaging; the lithium-ion battery is obtained by pouring electrolyte and forming a constant capacity.

[0177] Among them, the thickness T1mm of the separator 130 is 0.02mm, the number of empty winding turns n of the separator 130 is 20 turns, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.16mm, the thickness T3mm of the negative electrode substrate 111 is 0.004mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.12mm, the thickness T5mm of the positive electrode substrate 121 is 0.005mm, the length H1 of the negative electrode tab 113 in the first direction Z is 2mm, the length H2 of the positive electrode tab 123 in the first direction Z is 2mm, and 2H1 -2T1×n-(T2-T3) is 3.044, 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.685, the length L1mm of the positive electrode tab in the second direction X is 1mm, the length L2mm of the negative electrode tab in the second direction X is 1mm, and the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 0.5mm. The spacing W2mm between two adjacent negative electrode tabs in the second direction X is 0.5mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 10°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 10°.

[0178] Example 2

[0179] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0180] The thickness T1 of the diaphragm 130 is 0.015 mm, 2H1-2T1×n-(T2-T3) is 3.244, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.905.

[0181] Example 3

[0182] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0183] The thickness T1 mm of the diaphragm 130 is 0.011 mm, 2H1-2T1×n-(T2-T3) is 3.404, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.081.

[0184] Example 4

[0185] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0186] The thickness T1 mm of the diaphragm 130 is 0.009 mm, 2H1-2T1×n-(T2-T3) is 3.484, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.169.

[0187] Example 5

[0188] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0189] The thickness T1 mm of the diaphragm 130 is 0.006 mm, 2H1-2T1×n-(T2-T3) is 3.604, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.301.

[0190] Example 6

[0191] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0192] The thickness T2 mm of the portion of the negative electrode sheet 110 having the negative active material layer 112 is 0.2 mm, 2H1-2T1×n-(T2-T3) is 3.004, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.605.

[0193] Example 7

[0194] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0195] The total thickness T2 mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.15 mm, 2H1-2T1×n-(T2-T3) is 3.054, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.705.

[0196] Example 8

[0197] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0198] The total thickness T2 mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.1 mm, 2H1-2T1×n-(T2-T3) is 3.104, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.805.

[0199] Example 9

[0200] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0201] The total thickness T2 mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.05 mm, 2H1-2T1×n-(T2-T3) is 3.154, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.905.

[0202] Example 10

[0203] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0204] The thickness T3 mm of the negative electrode substrate 111 is 0.0045 mm, and 2H1-2T1×n-(T2-T3) is 3.0445.

[0205] Example 11

[0206] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0207] The thickness T3 mm of the negative electrode substrate 111 is 0.006 mm, and 2H1-2T1×n-(T2-T3) is 3.046.

[0208] Example 12

[0209] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0210] The thickness T3 mm of the negative electrode substrate 111 is 0.008 mm, and 2H1-2T1×n-(T2-T3) is 3.048.

[0211] Example 13

[0212] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0213] The thickness T3 mm of the negative electrode substrate 111 is 0.02 mm, and 2H1-2T1×n-(T2-T3) is 3.06.

[0214] Example 14

[0215] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0216] The number n of empty windings of the separator 130 is 10, 2H1-2T1×n-(T2-T3) is 3.444, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.085.

[0217] Example 15

[0218] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0219] The number n of empty windings of the separator 130 is 8, 2H1-2T1×n-(T2-T3) is 3.524, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.165.

[0220] Example 16

[0221] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0222] The number n of empty windings of the separator 130 is 5, 2H1-2T1×n-(T2-T3) is 3.644, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.285.

[0223] Example 17

[0224] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0225] The number n of empty windings of the separator 130 is 1, 2H1-2T1×n-(T2-T3) is 3.804, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.445.

[0226] Example 18

[0227] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0228] The length H1mm of the negative electrode tab 113 in the first direction Z is 3 mm, and 2H1-2T1×n-(T2-T3) is 5.044.

[0229] Example 19

[0230] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0231] The length H1 mm of the negative electrode tab 113 in the first direction Z is 3.2 mm, and 2H1-2T1×n-(T2-T3) is 5.444.

[0232] Example 20

[0233] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0234] The length H1 mm of the negative electrode tab 113 in the first direction Z is 3.8 mm, and 2H1-2T1×n-(T2-T3) is 6.644.

[0235] Example 21

[0236] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0237] The length H1mm of the negative electrode tab 113 in the first direction Z is 4 mm, and 2H1-2T1×n-(T2-T3) is 7.044.

[0238] Example 22

[0239] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0240] The length H2mm of the positive electrode tab 123 in the first direction Z is 3mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 4.685.

[0241] Example 23

[0242] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0243] The length H2mm of the positive electrode tab 123 in the first direction Z is 3.2mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 5.085.

[0244] Example 24

[0245] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0246] The length H2mm of the positive electrode tab 123 in the first direction Z is 3.5mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 5.685.

[0247] Example 25

[0248] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0249] The length H2mm of the positive electrode tab 123 in the first direction Z is 4 mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 6.685.

[0250] Example 26

[0251] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0252] The thickness T1mm of the separator 130 is 0.01mm, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.2mm, the thickness T3mm of the negative electrode substrate 111 is 0.0045mm, the length H1 of the negative electrode tab 113 in the first direction Z is 2.1mm, 2H1-2T1×n-(T2-T3) is 3.6045, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.045.

[0253] Example 27

[0254] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0255] The thickness T1mm of the separator 130 is 0.015mm, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.15mm, the thickness T3mm of the negative electrode substrate 111 is 0.006mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 2.3mm, 2H1-2T1×n-(T2-T3) is 3.856, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.925.

[0256] Example 28

[0257] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0258] The thickness T1mm of the separator 130 is 0.018mm, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.1mm, the thickness T3mm of the negative electrode substrate 111 is 0.008mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 2.8mm, 2H1-2T1×n-(T2-T3) is 4.788, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.893.

[0259] Example 29

[0260] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0261] The thickness T1mm of the separator 130 is 0.02mm, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.05mm, the thickness T3mm of the negative electrode substrate 111 is 0.02mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 3mm, 2H1-2T1×n-(T2-T3) is 5.17, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.905.

[0262] Example 30

[0263] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0264] The total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.2mm, the thickness T5mm of the positive electrode substrate 121 is 0.01mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 2.1mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 2.81.

[0265] Example 31

[0266] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0267] The total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.15mm, the thickness T5mm of the positive electrode substrate 121 is 0.013mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 2.3mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.263.

[0268] Example 32

[0269] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0270] The total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.1mm, the thickness T5mm of the positive electrode substrate 121 is 0.015mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 2.6mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 3.915.

[0271] Example 33

[0272] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0273] The total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.05mm, the thickness T5mm of the positive electrode substrate 121 is 0.03mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 3.1mm, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 4.98.

[0274] Example 34

[0275] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0276] The thickness T1mm of the separator 130 is 0.015mm, the number of empty winding turns n of the separator 130 is 10 turns, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.2mm, the thickness T3mm of the negative electrode substrate 111 is 0.0045mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.2mm, the thickness T5mm of the positive electrode substrate 121 is 0.01mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 4mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 4mm, 2H1-2T1×n-(T2-T3) is 7.5045, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 7.05.

[0277] Example 35

[0278] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0279] The thickness T1mm of the separator 130 is 0.011mm, the number of empty turns n of the separator 130 is 8 turns, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.15mm, the thickness T3mm of the negative electrode substrate 111 is 0.006mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.15mm, the thickness T5mm of the positive electrode substrate 121 is 0.013mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 5mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 5mm, 2H1-2T1×n-(T2-T3) is 9.68, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 9.343.

[0280] Example 36

[0281] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0282] The thickness T1mm of the separator 130 is 0.009mm, the number of empty turns n of the separator 130 is 5 turns, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.1mm, the thickness T3mm of the negative electrode substrate 111 is 0.008mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.1mm, the thickness T5mm of the positive electrode substrate 121 is 0.015mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 6mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 6mm, 2H1-2T1×n-(T2-T3) is 11.818, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 11.589.

[0283] Example 37

[0284] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0285] The thickness T1mm of the separator 130 is 0.006mm, the number of empty coils n of the separator 130 is 1 coil, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.05mm, the thickness T3mm of the negative electrode substrate 111 is 0.02mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.05mm, the thickness T5mm of the positive electrode substrate 121 is 0.03mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 10mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 10mm, 2H1-2T1×n-(T2-T3) is 19.958, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 19.844.

[0286] Example 38

[0287] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0288] The thickness T1mm of the separator 130 is 0.02mm, the number of empty winding turns n of the separator 130 is 20 turns, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.5mm, the thickness T3mm of the negative electrode substrate 111 is 0.002mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.5mm, the thickness T5mm of the positive electrode substrate 121 is 0.002mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 2mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 2mm, 2H1-2T1×n-(T2-T3) is 2.702, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 1.622.

[0289] Example 39

[0290] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0291] The length L1mm of the positive electrode tab in the second direction X is 2mm, the length L2mm of the negative electrode tab in the second direction X is 2mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 0.75mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 0.75mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 20°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 20°.

[0292] Example 40

[0293] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0294] The length L1mm of the positive electrode tab in the second direction X is 3mm, the length L2mm of the negative electrode tab in the second direction X is 3mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 1mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 1mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 30°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 30°.

[0295] Example 41

[0296] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0297] The length L1mm of the positive electrode tab in the second direction X is 4mm, the length L2mm of the negative electrode tab in the second direction X is 4mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 1.5mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 1.5mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 45°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 45°.

[0298] Example 42

[0299] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0300] The length L1mm of the positive electrode tab in the second direction X is 5mm, the length L2mm of the negative electrode tab in the second direction X is 5mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 2mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 2mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 60°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 60°.

[0301] Example 43

[0302] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0303] The length L1mm of the positive electrode tab in the second direction X is 6mm, the length L2mm of the negative electrode tab in the second direction X is 6mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 2.5mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 2.5mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 70°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 70°.

[0304] Example 44

[0305] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0306] The length L1mm of the positive electrode tab in the second direction X is 7mm, the length L2mm of the negative electrode tab in the second direction X is 7mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 3mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 3mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 75°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 75°.

[0307] Example 45

[0308] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0309] The length L1mm of the positive electrode tab in the second direction X is 8mm, the length L2mm of the negative electrode tab in the second direction X is 8mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 4mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 4mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 80°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 80°.

[0310] Example 46

[0311] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0312] The length L1mm of the positive electrode tab in the second direction X is 9mm, the length L2mm of the negative electrode tab in the second direction X is 9mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 4.5mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 4.5mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 85°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 85°.

[0313] Example 47

[0314] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0315] The length L1mm of the positive electrode tab in the second direction X is 10mm, the length L2mm of the negative electrode tab in the second direction X is 10mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 5mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 5mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 90°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 90°.

[0316] Example 48

[0317] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0318] The length L1mm of the positive electrode tab in the second direction X is 0.5mm, the length L2mm of the negative electrode tab in the second direction X is 0.5mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 0.2mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 0.2mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 0, and the angle α2 between the axis of the negative electrode tab and the second direction X is 0.

[0319] Example 49

[0320] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0321] The length L1mm of the positive electrode tab in the second direction X is 12mm, the length L2mm of the negative electrode tab in the second direction X is 12mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is 7mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is 7mm. The angle α1 between the axis of the positive electrode tab and the second direction X is 100°, and the angle α2 between the axis of the negative electrode tab and the second direction X is 100°.

[0322] Comparative Example 1

[0323] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0324] The thickness T1mm of the separator 130 is 0.03mm, the number of empty turns n of the separator 130 is 22 turns, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.7mm, the thickness T3mm of the negative electrode substrate 111 is 0.001mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.7mm, the thickness T5mm of the positive electrode substrate 121 is 0.001mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 1.8mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 1.8mm, 2H1-2T1×n-(T2-T3) is 1.581, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 0.061.

[0325] Comparative Example 2

[0326] A lithium-ion battery was prepared according to the method of Example 1, except that:

[0327] The thickness T1mm of the separator 130 is 0.004mm, the number of empty turns n of the separator 130 is 0, the total thickness T2mm of the negative electrode substrate 111 and the negative electrode active material layer 112 is 0.03mm, the thickness T3mm of the negative electrode substrate 111 is 0.03mm, the total thickness T4mm of the positive electrode substrate 121 and the positive electrode active material layer 122 is 0.03mm, the thickness T5mm of the positive electrode substrate 121 is 0.04mm, the length H1mm of the negative electrode tab 113 in the first direction Z is 12mm, the length H2mm of the positive electrode tab 123 in the first direction Z is 12mm, 2H1-2T1×n-(T2-T3) is 24, and 2H2-2T1×(n+2)-2T2-(T4-T5) is 23.934.

[0328] The batteries prepared in the above examples and comparative examples were subjected to performance tests. The specific test items were as follows:

[0329] 1. Test method for lithium-ion battery cycle performance

[0330] At 25°C, the prepared lithium-ion battery was charged at a constant capacity rate of 1C to the nominal capacity and discharged at a rate of 1C to 2.5V. A cycle test was performed until the capacity of the lithium-ion secondary battery decayed to 80% of the initial capacity, and the number of cycles was recorded.

[0331] The relevant parameters and test results in the above examples and comparative examples are recorded in Tables 1-2.

[0332] Table 1 Parameters of Examples 1 to 38 and parameters and test results of Comparative Examples 1 to 2

[0333] Result analysis: From the data analysis of the examples and comparative examples in Table 1, it can be seen that when 2H1-2T1×n-(T2-T3) is less than 2.702, the middle part of the electrode assembly is prone to deformation and collapse, thereby affecting the positive and negative electrode interfaces and resulting in a low battery cycle life;

[0334] When 2H1-2T1×n-(T2-T3) is greater than 19.958, the interface between the positive electrode sheet and the negative electrode sheet is poor, resulting in a low cycle life of the single battery.

[0335] In summary, this application limits 2H1-2T1×n-(T2-T3) to the range of 2.702 to 19.958 to ensure that the tab height is minimized when the tab is flattened in the single cell, thereby reducing the stacking height of the tabs, while ensuring that the thickness of the diaphragm is minimized and the total thickness of the active material layer is maximized, thereby increasing the height and thickness of the portion of the electrode with the active material layer, improving the cycle life of the single cell, and thereby improving the overall performance of the single cell.

[0336] Optionally, the present application limits 2H1-2T1×n-(T2-T3) to be within the range of 7.5045 to 11.818, so as to further improve the cycle life of the single cell and further improve the comprehensive performance of the single cell.

[0337] Compared with the comparative example, the cycle life of the single cells in the present application is significantly improved.

[0338] Table 2 Parameters and test results of Example 1 and Examples 39 to 49

[0339] Result analysis: From the analysis of the embodiment data in Table 2, it can be obtained that when the length L1mm of the positive electrode tab in the second direction X is less than 1mm, the length L2mm of the negative electrode tab in the second direction X is less than 1mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is less than 0.5mm, and the spacing W2mm between two adjacent negative electrode tabs in the second direction X is less than 0.5mm, the angle α1 between the axis of the positive electrode tab and the second direction X is equal to 10°, and the angle α2 between the axis of the negative electrode tab and the second direction X is equal to 10°, it may easily cause the tab to fold during winding, affecting the subsequent flat surface of the tab, and further affecting the electronic conduction path between the end face of the tab and the current collecting disk, resulting in a low cycle life of the single battery.

[0340] When the length L1mm of the positive electrode tab in the second direction X is greater than 10mm, the length L2mm of the negative electrode tab in the second direction X is greater than 10mm, the spacing W1mm between two adjacent positive electrode tabs in the second direction X is greater than 5mm, the spacing W2mm between two adjacent negative electrode tabs in the second direction X is greater than 5mm, the angle α1 between the axis of the positive electrode tab and the second direction X is greater than 90°, and the angle α2 between the axis of the negative electrode tab and the second direction X is greater than 90°, more gaps may exist inside the battery, resulting in low space utilization of the electrode assembly and a short cycle life of the single battery.

[0341] In summary, the present application improves the cycle life of the single cell by limiting the length L1mm of the positive electrode tab in the second direction X to be in the range of 1mm to 10mm, the length L2mm of the negative electrode tab in the second direction X to be in the range of 1mm to 10mm, the spacing W1mm between two adjacent positive electrode tabs to be in the range of 0mm to 5mm, the spacing W2mm between two adjacent negative electrode tabs to be in the range of 0mm to 5mm, the angle α1 between the axis of the positive electrode tab and the second direction X to be in the range of 0° to 90°, and the angle α2 between the axis of the negative electrode tab and the second direction X to be in the range of 0° to 90°.

[0342] Optionally, the present application further improves the cycle life of the single cell by limiting the length L1mm of the positive electrode tab in the second direction X to be in the range of 3mm to 5mm, the length L2mm of the negative electrode tab in the second direction X to be in the range of 3mm to 5mm, the spacing W1mm between two adjacent positive electrode tabs to be in the range of 0mm to 2mm, the spacing W2mm between two adjacent negative electrode tabs to be in the range of 0mm to 2mm, the angle α1 between the axis of the positive electrode tab and the second direction X to be in the range of 30° to 60°, and the angle α2 between the axis of the negative electrode tab and the second direction X to be in the range of 30° to 60°.

[0343] Compared with the comparative example, the cycle life of the single cells in the present application is significantly improved.

[0344] The above is a detailed introduction to the single cell and battery module provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those skilled in the art, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A single cell having a first direction (Z), wherein: The single cell battery comprises: case; An electrode assembly, accommodated in the housing; The electrode assembly comprises: a positive electrode sheet (120), a separator (130) and a negative electrode sheet (110) which are stacked, wherein the separator (130) is arranged between the positive electrode sheet (120) and the negative electrode sheet (110), and the positive electrode sheet (120), the negative electrode sheet (110) and the separator (130) are wound together to form the electrode assembly; The negative electrode plate (110) comprises: A negative electrode substrate (111); A negative electrode active material layer (112) is coated on the negative electrode substrate (111); and A negative electrode tab (113) extending along the first direction (Z) and connected to the negative electrode substrate (111); Wherein, the single cell satisfies: 2.702≤2H1-2T1×n-(T2-T3)≤19.958; H1mm is the length of the negative electrode tab (113) in the first direction (Z), T1mm is the thickness of the separator (130), n is the number of empty turns of the separator (130), T2mm is the total thickness of the negative electrode substrate (111) and the negative electrode active material layer (112), and T3mm is the thickness of the negative electrode substrate (111).

2. The single cell according to claim 1, wherein: The single cell further satisfies: 7.5045≤2H1-2T1×n-(T2-T3)≤11.

818.

3. The single cell according to claim 1, wherein: The length H1 mm of the negative electrode tab (113) in the first direction (Z) satisfies: 2≤H1≤10.

4. The single cell according to claim 1, wherein: The length H1 mm of the negative electrode tab (113) in the first direction (Z) satisfies: 4≤H1≤6.

5. The single cell according to claim 1, wherein: The positive electrode plate (120) comprises: a positive electrode substrate (121); A positive electrode active material layer (122) is coated on the positive electrode substrate (121); and A positive electrode tab (123), extending along the first direction (Z) and connected to the positive electrode substrate (121); The single cell also satisfies: 1.622≤2H2-2T1×(n+2)-2T2-(T4-T5)≤19.844; Wherein, H2mm is the length of the positive electrode tab (123) in the first direction (Z), T4mm is the total thickness of the positive electrode substrate (121) and the positive electrode active material layer (122), and T5mm is the thickness of the positive electrode substrate (121).

6. The single cell according to claim 5, wherein: The single cell also satisfies: 7.05≤2H2-2T1×(n+2)-2T2-(T4-T5)≤11.

589.

7. The single cell according to claim 5, wherein: The length H2 mm of the positive electrode tab (123) in the first direction (Z) satisfies: 2≤H2≤10.

8. The single cell according to claim 7, wherein: The length H2 mm of the positive electrode tab (123) in the first direction (Z) also satisfies: 4≤H2≤6.

9. The single cell according to claim 1, wherein: The thickness T1 mm of the diaphragm (130) satisfies: 0.006≤T1≤0.02; or the thickness T1 mm of the diaphragm (130) satisfies: 0.009≤T1≤0.

015.

10. The single cell according to claim 1, wherein: The number n of empty windings of the diaphragm (130) satisfies: 0<n≤20; or, the number n of empty windings of the diaphragm (130) satisfies: 5≤n≤10.

11. The single cell according to claim 1, wherein: The total thickness T2 mm of the negative electrode substrate (111) and the negative electrode active material layer (112) satisfies: 0.05≤T2≤0.5; The thickness T3 mm of the negative electrode substrate (111) satisfies: 0.002≤T3≤0.

02.

12. The single cell according to claim 11, wherein: The total thickness T2 mm of the negative electrode substrate (111) and the negative electrode active material layer (112) satisfies: 0.1≤T2≤0.2; The thickness T3 mm of the negative electrode substrate (111) satisfies: 0.0045≤T3≤0.

008.

13. The single cell according to claim 5, wherein: The total thickness T4 mm of the positive electrode substrate (121) and the positive electrode active material layer (122) satisfies: 0.05≤T4≤0.5; The thickness T5 mm of the positive electrode substrate (121) satisfies: 0.002≤T5≤0.

03.

14. The single cell according to claim 13, wherein: The total thickness T4 mm of the positive electrode substrate (121) and the positive electrode active material layer (122) satisfies: 0.1≤T4≤0.2; and / or, The thickness T5 mm of the positive electrode substrate (121) satisfies: 0.01≤T5≤0.

015.

15. The single cell according to claim 5, wherein: When the positive electrode sheet (120) is unfolded, the positive electrode sheet (120) has a second direction (X) intersecting with the first direction (Z), and the size of the positive electrode tab (123) in the second direction (X) is L1 mm, satisfying: 1≤L1≤10; In the second direction (X), the distance between two adjacent positive electrode tabs (123) is W1 mm, satisfying: 0<W1≤5; The positive electrode tab (123) has an axis, and the angle between the axis of the positive electrode tab (123) and the second direction (X) is α1, satisfying: 0<α1≤90°.

16. The single cell according to claim 1, wherein: When the negative electrode sheet (110) is unfolded, the negative electrode sheet (110) has a second direction (X) intersecting the first direction (Z), and the size of the negative electrode tab (113) in the second direction (X) is L2 mm, satisfying: 1≤L2≤10; In the second direction (X), the distance between two adjacent negative electrode tabs (113) is W2 mm, satisfying: 0<W2≤5; The negative electrode tab (113) has an axis, and the angle between the axis of the negative electrode tab (113) and the second direction (X) is α2, satisfying: 0<α2≤90°.

17. The single cell according to claim 15, wherein: The dimension L1mm of the positive electrode tab (123) in the second direction (X) satisfies: 3≤L1≤5; In the second direction (X), the spacing W1mm between two adjacent positive electrode tabs (123) satisfies: 0<W1≤2mm; The angle α1 between the axis of the positive electrode tab (123) and the second direction (X) satisfies: 30°≤α1≤60°.

18. The single cell according to claim 16, wherein: The dimension L2 mm of the negative electrode tab (113) in the second direction (X) satisfies: 3≤L2≤5; In the second direction (X), the spacing W2 mm between two adjacent negative electrode tabs (113) satisfies: 0<W2≤2; An angle α2 between the axis of the negative electrode tab and the second direction (X) satisfies: 30°≤α2≤60°.

19. A battery module, characterized in that: include: Containing box; And the single cell according to any one of claims 1 to 18, wherein the single cell is accommodated in the housing box.

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