Battery monomer, battery and electric equipment

Abstract

The invention discloses a battery monomer (20), a battery (100) and electric equipment. The battery monomer (20) comprises an electrode assembly (23), a positive electrode leading-out part (24), a positive electrode connecting assembly (25), a negative electrode leading-out part (26) and a negative electrode connecting assembly (27), the positive electrode connecting assembly (25) is connected with the positive electrode plate (231) and the positive electrode leading-out part (24); the negative electrode connecting assembly (27) is electrically connected with the negative electrode plate (232) and the negative electrode leading-out part (26); the minimum overcurrent sectional area of the positive connecting assembly (25) is smaller than the overcurrent sectional area of the positive lead-out part (24), the melting point of the positive connecting assembly (25) is smaller than the melting point of the negative connecting assembly (27), the minimum overcurrent sectional area of the positive connecting assembly (25) is A1, the unit is mm < 2 >, the minimum overcurrent sectional area of the negative connecting assembly (27) is A2, the unit is mm < 2 >, the melting point of the positive connecting assembly (25) is B1, the unit is DEG C, and the unit is C; the melting point of the positive electrode connecting assembly (25) is B1, the unit is DEG C, the melting point of the negative electrode connecting assembly (27) is B2, the resistivity of the positive electrode connecting assembly (25) is C1, the unit is Omega m, the resistivity of the negative electrode connecting assembly (27) is C2, the unit is Omega m, A1 is smaller than A2 * (B2 / B1) * (C1 / C2), the risk that the battery monomer (20) is on fire, explodes and the like is reduced, and the reliability of the battery monomer (20) is improved.

Description

Battery cells, batteries and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application (202322662093.1) entitled “Battery Cell, Battery and Electrical Equipment” filed on September 28, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0004] Battery cells are widely used in electronic devices, vehicles, power tools, drones, energy storage devices, and other fields. As application environments and conditions become increasingly complex, higher requirements are placed on the reliability of battery cells.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a battery cell, a battery, and an electrical device to improve the reliability of the battery cell.

[0007] In a first aspect, an embodiment of the present application provides a battery cell, the battery cell comprising an electrode assembly, a positive electrode lead-out portion, a positive electrode connection assembly, a negative electrode lead-out portion, and a negative electrode connection assembly; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet; the positive electrode connection assembly electrically connects the positive electrode sheet and the positive electrode lead-out portion, the positive electrode lead-out portion being used to electrically connect to components external to the battery cell; the negative electrode connection assembly electrically connects the negative electrode sheet and the negative electrode lead-out portion, the negative electrode lead-out portion being used to electrically connect to components external to the battery cell; wherein the minimum cross-sectional area of ​​the positive electrode connection assembly is smaller than the The overflow cross-sectional area of ​​the positive electrode lead-out portion, the melting point of the positive electrode connection assembly is less than the melting point of the negative electrode connection assembly, the minimum overflow cross-sectional area of ​​the positive electrode connection assembly is A1, in mm2, the minimum overflow cross-sectional area of ​​the negative electrode connection assembly is A2, in mm2, the melting point of the positive electrode connection assembly is B1, in °C, the melting point of the negative electrode connection assembly is B2, in °C, the resistivity of the positive electrode connection assembly is C1, in Ωm, the resistivity of the negative electrode connection assembly is C2, in Ωm, satisfying: A1<A2*(B2 / B1)*(C1 / C2).

[0008] In the above technical solution, the melting point of the positive electrode connection assembly is lower than the melting point of the negative electrode connection assembly, the minimum flow cross-sectional area A1 of the positive electrode connection assembly, the minimum flow cross-sectional area A2 of the negative electrode connection assembly, the melting point B1 of the positive electrode connection assembly, the melting point B2 of the negative electrode connection assembly, and the resistivity C1 of the positive electrode connection assembly satisfy: A1<A2*(B2 / B1)*(C1 / C2), so that when the battery cell is short-circuited, the fuse position occurs in the positive electrode connection assembly. In this way, the overall temperature of the battery cell is lower when the short-circuit path of the battery cell is melted, thereby reducing the risk of fire, explosion and other problems in the battery cell and improving the reliability of the battery cell.

[0009] In some embodiments of the first aspect of the present application, A1≤2.5A2.

[0010] In the above technical solution, A1≤2.5A2, which makes the positive electrode connection assembly have better current carrying capacity and also enables the positive electrode connection assembly to melt when the battery cell is short-circuited, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the risk of fire, explosion and other problems and improving the reliability of the battery cell.

[0011] In some embodiments of the first aspect of the present application, A1≤2.3A2.

[0012] In the above technical solution, A1≤2.3A2, so that the positive electrode connection assembly has better current capacity and meets more usage requirements. It also enables the positive electrode connection assembly to melt when the battery cell is short-circuited, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the risk of fire, explosion and other problems and improving the reliability of the battery cell.

[0013] In some embodiments of the first aspect of the present application, A1≤1.5A2.

[0014] In the above technical solution, A1≤1.5A2, so that when the battery cell is short-circuited, the positive electrode connection assembly can be melted, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell has better reliability.

[0015] In some embodiments of the first aspect of the present application, A1<A2.

[0016] In the above technical solution, A1<A2, and when the melting point of the positive electrode connection component is lower than the melting point of the negative electrode connection component, when the battery cell is short-circuited, the positive electrode connection component can be melted, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell has better reliability.

[0017] In some embodiments of the first aspect of the present application, the positive electrode tab includes a plurality of positive electrode tab portions arranged in a stacked manner, the negative electrode connection assembly includes a negative electrode tab, the negative electrode tab is connected to the negative electrode sheet, and the negative electrode tab includes a plurality of negative electrode tab portions arranged in a stacked manner; the number of the positive electrode tab portions is less than the number of the negative electrode tab portions.

[0018] In the above technical solution, the number of positive electrode ears is smaller than that of negative electrode ears, which is beneficial for the negative electrode ears to have a larger flow cross-sectional area, so that the negative electrode connection assembly is less likely to melt.

[0019] In some embodiments of the first aspect of the present application, the negative electrode connection assembly includes a negative electrode tab, the negative electrode tab is connected to the negative electrode sheet, and the width of the positive electrode tab is smaller than the width of the negative electrode tab.

[0020] In the above technical solution, the width of the positive electrode ear is smaller than that of the negative electrode ear, which is beneficial for the negative electrode ear to have a larger flow cross-sectional area, so that the negative electrode connection assembly is less likely to melt.

[0021] In some embodiments of the first aspect of the present application, the positive electrode connection assembly includes a positive electrode tab, which is connected to the positive electrode sheet, and the flow cross-sectional area of ​​the positive electrode tab is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion.

[0022] In the above technical solution, the minimum flow cross-sectional area of ​​the positive electrode tab is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion, so the melting can occur in the positive electrode connection assembly. The structure of the positive electrode tab itself can be utilized to achieve melting of the positive electrode connection assembly when the battery cell is short-circuited, making the structure of the battery cell simpler.

[0023] In some embodiments of the first aspect of the present application, the rated capacity of the battery cell is W, in units of Ah, and satisfies A1 / W≥0.15.

[0024] In the above technical solution, A1 / W≥0.15, so that the positive electrode ear has better overcurrent capacity, and can also make the temperature rise at the positive electrode ear larger, reducing the risk of melting of the negative electrode connection component when the battery cell is short-circuited, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the occurrence of fire, explosion and other problems, so that the battery cell has better reliability.

[0025] In some embodiments of the first aspect of the present application, the positive electrode tab is connected to the positive electrode lead-out portion.

[0026] In the above technical solution, the positive electrode tab is connected to the positive electrode lead-out portion, and the positive electrode connection assembly is not provided with a positive electrode adapter, which can simplify the structure of the battery cell.

[0027] In some embodiments of the first aspect of the present application, the positive electrode connection assembly further includes a positive electrode adapter, which connects the positive electrode ear and the positive electrode lead-out portion, and the positive electrode adapter includes a first welding area, a second welding area and a transition connection portion, the first welding area is connected to the positive electrode ear, the second welding area is connected to the positive electrode lead-out portion, and the transition connection portion is connected between the first welding area and the second welding area; the cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the first welding area, and / or the cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the second welding area.

[0028] In the above technical solution, the positive electrode tab and the positive electrode lead are connected via the positive electrode adapter, facilitating electrical connection between the positive electrode tab and the positive electrode lead, thereby improving the current handling capacity of the positive electrode connector assembly. The minimum cross-sectional area of ​​the transition portion is greater than or equal to the cross-sectional area of ​​the first weld zone, and / or the minimum cross-sectional area of ​​the transition portion is greater than or equal to the cross-sectional area of ​​the second weld zone. A larger cross-sectional area of ​​the transition portion can improve the current handling capacity of the transition portion, reduce the temperature rise of the positive electrode adapter, and reduce the risk of the positive electrode adapter fusing.

[0029] In some embodiments of the first aspect of the present application, the positive electrode connection assembly further includes a positive electrode adapter and a positive electrode lug, the positive electrode lug is connected to the positive electrode sheet, the positive electrode adapter connects the positive electrode lug and the positive electrode lead-out portion, the flow cross-sectional area of ​​the positive electrode adapter is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion, and the minimum flow cross-sectional area of ​​the positive electrode adapter is smaller than the flow cross-sectional area of ​​the positive electrode lug.

[0030] In the above technical solution, the positive electrode tab and the positive electrode lead are connected via a positive electrode adapter, facilitating electrical connection between the positive electrode tab and the positive electrode lead, thereby improving the current carrying capacity of the positive electrode connection assembly. The minimum current carrying cross-sectional area of ​​the positive electrode adapter is smaller than the current carrying cross-sectional area of ​​the positive electrode lead, and the minimum current carrying cross-sectional area of ​​the positive electrode adapter is smaller than the current carrying cross-sectional area of ​​the positive electrode tab. Therefore, when a short circuit occurs in a battery cell, the positive electrode adapter fuses, thereby severing the short-circuit path. When the positive electrode connection assembly fuses, the overall temperature of the battery cell is reduced when the short-circuit path of the battery cell is severed, thereby reducing the risk of fire, explosion, and other problems, thereby improving the reliability of the battery cell.

[0031] In some embodiments of the first aspect of the present application, the positive electrode adapter includes a first welding area, a second welding area and a transition connection portion, the first welding area is connected to the positive electrode ear, the second welding area is connected to the positive electrode lead-out portion, and the transition connection portion is connected between the first welding area and the second welding area; the cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the first welding area, and / or the cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the second welding area.

[0032] In the above technical solution, the minimum cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the first welding zone, and / or the minimum cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the second welding zone, which is conducive to the positive electrode adapter having a higher current capacity.

[0033] In some embodiments of the first aspect of the present application, the rated capacity of the battery cell is W, in units of Ah, and satisfies A1 / W≥0.2.

[0034] In the above technical solution, A1 / W≥0.2, so that the positive electrode adapter has better current capacity and can also make the temperature rise at the positive electrode adapter larger, reducing the risk of melting of the negative electrode connection component when the battery cell is short-circuited, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the occurrence of fire, explosion and other problems, so that the battery cell has better reliability.

[0035] In some embodiments of the first aspect of the present application, the thickness of at least a portion of the positive electrode adapter is H1, satisfying 1.0 mm ≤ H1 ≤ 1.5 mm.

[0036] In the above technical solution, the thickness H1 of at least part of the positive electrode adapter satisfies 1.0mm≤H1≤1.5mm, which is beneficial for the positive electrode adapter to have better current carrying capacity, is beneficial for improving the formation of a fast-charging battery, and is also convenient for the positive electrode ear and the positive electrode lead-out part to be connected to the positive electrode adapter respectively, which is beneficial for improving the connection stability between the positive electrode ear and the positive electrode adapter, as well as the connection stability between the positive electrode lead-out part and the positive electrode adapter.

[0037] In some embodiments of the first aspect of the present application, the positive electrode adapter includes a first connecting portion and a second connecting portion, the first connecting portion is connected to the positive electrode ear, the second connecting portion is connected to the positive electrode lead-out portion, the thickness of the first connecting portion is greater than or equal to the thickness of the second connecting portion, and the thickness of the first connecting portion is H1, satisfying 1.0mm≤H1≤1.5mm.

[0038] In the above technical solution, the thickness of the first connecting portion is greater than that of the second connecting portion, which can improve the current carrying capacity of the positive electrode adapter and improve the welding quality of the positive electrode lead portion and the positive electrode adapter.

[0039] In some embodiments of the first aspect of the present application, the material of the positive electrode tab is aluminum; and / or the material of the positive electrode adapter is aluminum.

[0040] In the above technical solution, the material of the positive electrode ear and / or the positive electrode adapter is aluminum, which not only makes the positive electrode connection assembly have better current carrying capacity, but also makes the positive electrode adapter assembly easier to melt, so that when the battery cell is short-circuited, the positive electrode connection assembly can be melted, thereby reducing the overall temperature of the battery cell when the short-circuit path of the battery cell is cut off, thereby reducing the occurrence of fire, explosion and other problems, so that the battery cell has better reliability.

[0041] In some embodiments of the first aspect of the present application, the negative electrode connection assembly further includes a negative electrode adapter and a negative electrode tab, the negative electrode tab is connected to the negative electrode sheet, and the negative electrode adapter connects the negative electrode tab and the negative electrode lead-out portion.

[0042] In the above technical solution, the negative electrode ear and the negative electrode lead-out portion are connected via a negative electrode adapter, which facilitates electrical connection between the negative electrode ear and the negative electrode lead-out portion and is beneficial to improving the current carrying capacity of the negative electrode connection assembly.

[0043] In some embodiments of the first aspect of the present application, the minimum flow cross-sectional area of ​​the negative electrode adapter is greater than the maximum flow cross-sectional area of ​​the negative electrode lug; or, the minimum flow cross-sectional area of ​​the negative electrode lug is greater than the maximum flow cross-sectional area of ​​the negative electrode adapter.

[0044] In the above technical solution, the minimum flow cross-sectional area of ​​the negative electrode adapter is larger than the maximum flow cross-sectional area of ​​the negative electrode ear, so that the flow capacity of the negative electrode adapter is better, which is conducive to the formation of a fast-charging battery; the minimum flow cross-sectional area of ​​the negative electrode ear is larger than the maximum flow cross-sectional area of ​​the negative electrode adapter, which is conducive to the negative electrode ear having better flow capacity.

[0045] In some embodiments of the first aspect of the present application, the thickness of at least a portion of the negative electrode adapter is H2, satisfying 0.6 mm ≤ H2 ≤ 1.0 mm.

[0046] In the above technical solution, the thickness H2 of at least part of the negative electrode adapter satisfies 0.6mm≤H2≤1.0mm, which is conducive to the negative electrode adapter having better current carrying capacity, is conducive to the formation of a fast-charging battery, and is also convenient for the negative electrode ear and the negative electrode lead-out part to be connected to the negative electrode adapter respectively, which is conducive to improving the connection stability between the negative electrode ear and the negative electrode adapter and the connection stability between the negative electrode lead-out part and the negative electrode adapter.

[0047] In some embodiments of the first aspect of the present application, the negative electrode adapter includes a third connecting portion and a fourth connecting portion, the third connecting portion is connected to the negative electrode ear, the fourth connecting portion is connected to the negative electrode lead-out portion, the thickness of the third connecting portion is greater than or equal to the thickness of the fourth connecting portion, and the thickness of the third connecting portion is H2, satisfying 0.6mm≤H2≤1.0mm.

[0048] In the above technical solution, the thickness of the third connecting portion is greater than that of the fourth connecting portion, which can improve the current carrying capacity of the negative electrode adapter and at the same time improve the welding quality of the negative electrode lead portion and the negative electrode adapter.

[0049] In some embodiments of the first aspect of the present application, the minimum flow cross-sectional area of ​​the positive electrode connection assembly is smaller than the minimum flow cross-sectional area of ​​the negative electrode tab.

[0050] In the above technical solution, the minimum flow cross-sectional area of ​​the positive electrode connection assembly is smaller than the minimum flow cross-sectional area of ​​the negative electrode ear, which is conducive to melting at the positive electrode connection when the battery cell is short-circuited, thereby reducing the overall temperature of the battery cell when the short-circuit path is melted, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell has better reliability.

[0051] In some embodiments of the first aspect of the present application, the negative electrode tab is made of copper; and / or the negative electrode adapter is made of copper.

[0052] In the above technical solution, the negative electrode ear and / or the negative electrode adapter is made of copper, so that the negative electrode connection assembly has a good current capacity, which is conducive to fast charging of the battery cell.

[0053] In some embodiments of the first aspect of the present application, the flow cross-sectional area of ​​the negative electrode connection assembly is smaller than the flow cross-sectional area of ​​the negative electrode lead-out portion.

[0054] In the above technical solution, the cross-sectional area of ​​the negative electrode connection assembly is smaller than the cross-sectional area of ​​the negative electrode lead-out portion, which is beneficial for the negative electrode lead-out portion to have a higher current capacity, thereby improving the reliability of the battery cell.

[0055] In some embodiments of the first aspect of the present application, the average charging rate of the battery cells is K, satisfying K≥2.

[0056] In the above technical solution, K≥2, which can achieve fast charging of battery cells.

[0057] In some embodiments of the first aspect of the present application, the positive electrode connection assembly includes a positive electrode ear, and the positive electrode ear includes a plurality of positive electrode ear portions arranged in a stacked manner; the negative electrode connection assembly includes a negative electrode ear, and the negative electrode ear includes a plurality of negative electrode ear portions arranged in a stacked manner; the electrode assembly is a wound electrode assembly, the number of negative electrode ears of the electrode assembly is M1, and the number of negative electrode sheet layers of the electrode assembly is M2, satisfying: 1 / 2≤M1 / M2≤1; and / or, the number of positive electrode ears of the electrode assembly is N1, and the number of positive electrode sheet layers of the electrode assembly is N2, satisfying: 1 / 2≤N1 / N2≤1; optionally, 1 / 2<M1 / M2≤3 / 4, 1 / 2≤N1 / N2≤3 / 4.

[0058] In the above technical solution, 1 / 2≤M1 / M2≤1, and / or, 1 / 2≤N1 / N2≤1, can not only make the positive and negative ears have higher current capacity, but also help to improve the charging rate of the battery cell, form a fast charging battery, and can also reduce the space occupied by the positive ear (the positive ear is thicker).

[0059] In some embodiments of the first aspect of the present application, the battery cell includes two electrode assemblies.

[0060] In the above technical solution, the battery cell includes two electrode assemblies, which is beneficial for the battery cell to have a higher energy density.

[0061] In some embodiments of the first aspect of the present application, the negative electrode sheet includes a negative electrode active material layer, and the specific surface area of ​​the negative electrode active material layer particles is 0.5 m2 / g to 5 m2 / g.

[0062] In the above technical solution, the specific surface area of ​​the negative electrode active material layer particles is 0.5m2 / g~5m2 / g, which can increase the ion embedding sites of the negative electrode active material and increase the rate of ion embedding into the negative electrode active material, thereby improving the charging efficiency of the battery cell and improving the fast charging capability of the battery cell.

[0063] In some embodiments of the first aspect of the present application, the negative electrode sheet includes a negative electrode active material layer, and the volume distribution particle size DV50 of the negative electrode active material layer is ≤15 μm.

[0064] In the above technical solution, the volume distribution particle size DV50 of the negative electrode active material layer is ≤15μm, the volume distribution particle size of the negative electrode active material is small, the negative electrode active material has more active reaction sites, and can receive ions faster, thereby improving the charging efficiency of the battery cell and enhancing the fast charging capability of the battery cell.

[0065] In some embodiments of the first aspect of the present application, the negative electrode sheet includes a negative electrode active material layer, and the coating weight per unit area of ​​the negative electrode active material layer is less than or equal to 150 mg / 1540.25 mm2.

[0066] In the above technical solution, the coating weight per unit area of ​​the negative electrode active material layer is less than or equal to 150mg / 1540.25mm2. The low coating weight per unit area of ​​the negative electrode active material layer allows the negative electrode active material layer to have a smaller thickness, thereby reducing the resistance to ion insertion into the negative electrode active material layer during charging and improving the charging efficiency of the battery cell. A thinner negative electrode sheet can also increase the number of winding layers of the negative electrode sheet, thereby allowing for the provision of more negative electrode ears, which is beneficial for improving the negative electrode's current carrying capacity and also facilitates fast charging of the battery cell.

[0067] In some embodiments of the first aspect of the present application, the battery cell further includes an electrolyte, and the ionic conductivity of the electrolyte is 9 mS / cm to 16 mS / cm.

[0068] In the above technical solution, the ionic conductivity of the electrolyte is 9mS / cm~16mS / cm. The electrolyte has good ionic conductivity, which can reduce the impedance of the battery cell and increase the migration rate of ions, thereby improving the charging efficiency of the battery cell and improving the fast charging capability of the battery cell.

[0069] In some embodiments of the first aspect of the present application, the DC impedance of the battery cell is less than or equal to 0.4 milliohms.

[0070] In the above technical solution, the DC impedance of the battery cell is less than or equal to 0.4 milliohms, which makes the ions migrate faster between the positive electrode and the negative electrode, and the charging rate of the battery cell is faster, which is conducive to the formation of a fast-charging battery.

[0071] In a second aspect, an embodiment of the present application further provides a battery, comprising a battery cell provided by any of the above embodiments.

[0072] In the above technical solutions, the battery cell provided by any of the above embodiments has good reliability, and the battery including the battery cell also has good reliability.

[0073] In some embodiments of the second aspect of the present application, the battery further includes a plurality of thermal management components arranged along a first direction, the thermal management components being used to adjust the temperature of the battery cells, and a plurality of battery cells arranged along a second direction are arranged between two adjacent thermal management components, and the first direction is perpendicular to the second direction.

[0074] In the above technical solution, the arrangement direction of the thermal management components is perpendicular to the arrangement direction of the battery cells, so one thermal management component can simultaneously perform heat exchange with multiple battery cells, which can improve the temperature regulation efficiency.

[0075] In some embodiments of the second aspect of the present application, the thermal management component is adhesively connected to the outer surface of the battery cell.

[0076] In the above technical solution, the thermal management component and the outer surface of the battery cell are bonded and connected so that the thermal management component and the battery cell have a stable relative position relationship, which is beneficial to improving the heat exchange efficiency.

[0077] In a third aspect, an embodiment of the present application further provides an electrical device, including the battery cell provided in the embodiment.

[0078] In the above technical solutions, the battery cell provided by any of the above embodiments has good reliability, which is beneficial to improving the reliability of power supply through the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0080] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0081] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0082] FIG3 is an exploded view of a battery cell provided in some embodiments of the present application;

[0083] FIG4 is a schematic diagram of the assembled cover, positive electrode lead-out portion, and negative electrode lead-out portion provided in some embodiments of the present application;

[0084] FIG5 is a cross-sectional view taken along the P1-P1 direction in FIG4 ;

[0085] FIG6 is a schematic diagram of the assembled cover, positive electrode lead-out portion, and negative electrode lead-out portion provided in other embodiments of the present application;

[0086] FIG7 is a cross-sectional view taken along the P2-P2 direction in FIG6 ;

[0087] FIG8 is a schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0088] FIG9 is another perspective of a schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0089] FIG10 is a schematic diagram of electrode assemblies provided in some other embodiments of the present application;

[0090] FIG11 is another perspective of schematic diagrams of electrode assemblies provided in other embodiments of the present application;

[0091] FIG12 is a schematic diagram of the connection between a tab and an adapter provided in some embodiments of the present application;

[0092] FIG13 is another perspective of a schematic diagram of the connection between a tab and an adapter provided in some embodiments of the present application;

[0093] FIG14 is a cross-sectional view taken along the P3-P3 direction in FIG14 ;

[0094] FIG15 is a schematic diagram of the connection between the tab and the adapter provided in other embodiments of the present application;

[0095] FIG16 is an enlarged view of point D1 in FIG15 ;

[0096] FIG17 is an enlarged view of point D2 in FIG15 ;

[0097] FIG18 is a schematic diagram of the connection between a tab and an adapter provided in some other embodiments of the present application;

[0098] FIG19 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application;

[0099] FIG20 is a schematic structural diagram of an electrode assembly provided in some other embodiments of the present application;

[0100] FIG21 is a schematic diagram of the structure of batteries provided in other embodiments of the present application.

[0101] Icons: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-shell; 22-cover; 221-pressure relief mechanism; 222-liquid injection hole; 223-sealing nail; 224-protective member; 23-electrode assembly; 231-positive plate; 2311-first end face; 232-negative plate; 2321-second end face; 24-positive lead-out portion; 241-first part; 242-second part; 243-third part; 25-positive connection assembly; 251-positive ear; 2511-positive ear portion; 2512-first side face; 2513-first arc surface; 252-positive adapter; 2521-first connection portion; 2522-second connection portion; 252a-first Welding area; 252b-second welding area; 252c-transition connection part; 26-negative electrode lead-out part; 261-fourth part; 262-fifth part; 263-sixth part; 27-negative electrode connection assembly; 271-negative electrode ear; 2711-negative electrode ear; 2712-second side; 2713-second arc surface; 272-negative electrode adapter; 2721-third connection part; 2722-fourth connection part; 30-thermal management component; 200-controller; 300-motor; Q1-first connection position; Q2-second connection position; X1-width direction of the positive electrode ear; Y1-width direction of the positive electrode sheet; Z1-thickness direction of the electrode assembly; X2-first direction; Y2-second direction; R1-melting area; E1-straight part; E2-bending part 2. DETAILED DESCRIPTION

[0102] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0103] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0104] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0105] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0106] In the description of the embodiments of the present application, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present application. In addition, the terms "first," "second," "third," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0107] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0108] After a battery cell short-circuits, its temperature rises dramatically, the short-circuit path melts, and the temperature of the battery cell stops rising. If the short-circuit path melts, the battery cell temperature is lower, and the risk of reliability issues such as fire and explosion is reduced. If the melt is located on the negative electrode side, the material on the negative electrode has a higher melting point, resulting in a higher temperature for the entire battery cell at the time of the melt, which is more likely to cause reliability issues such as fire and explosion.

[0109] Based on the above considerations, in order to alleviate the reliability problem caused by the high temperature of the battery cell when it is short-circuited and melted, the embodiment of the present application provides a battery cell, which includes an electrode assembly, a positive lead-out portion, a positive connection assembly, a negative lead-out portion and a negative connection assembly; the electrode assembly includes a positive electrode sheet and a negative electrode sheet; the positive connection assembly electrically connects the positive electrode sheet and the positive lead-out portion, and the positive electrode lead-out portion is used to electrically connect to components outside the battery cell; the negative connection assembly electrically connects the negative electrode sheet and the negative lead-out portion, and the negative electrode lead-out portion is used to electrically connect to components outside the battery cell; wherein, the positive connection assembly The minimum flow cross-sectional area is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion, the melting point of the positive electrode connection assembly is smaller than the melting point of the negative electrode connection assembly, the minimum flow cross-sectional area of ​​the positive electrode connection assembly is A1, in mm2, the minimum flow cross-sectional area of ​​the negative electrode connection assembly is A2, in mm2, the melting point of the positive electrode connection assembly is B1, in °C, the melting point of the negative electrode connection assembly is B2, in °C, the resistivity of the positive electrode connection assembly is C1, in Ωm, the resistivity of the negative electrode connection assembly is C2, in Ωm, satisfying: A1<A2*(B2 / B1)*(C1 / C2).

[0110] The melting point of the positive electrode connection component is lower than the melting point of the negative electrode connection component, the minimum flow cross-sectional area A1 of the positive electrode connection component, the minimum flow cross-sectional area A2 of the negative electrode connection component, the melting point B1 of the positive electrode connection component, the melting point B2 of the negative electrode connection component, and the resistivity C1 of the positive electrode connection component satisfy: A1<A2*(B2 / B1)*(C1 / C2), so that when the battery cell is short-circuited, the melting position occurs in the positive electrode connection component. In this way, the overall temperature of the battery cell is lower when the short-circuit path of the battery cell is melted, thereby reducing the risk of fire, explosion and other problems in the battery cell and improving the reliability of the battery cell.

[0111] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical equipment such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to improve the reliability of the battery cells.

[0112] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0113] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0114] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 can be arranged at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source or a power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0115] In some embodiments of the present application, the battery 100 can not only serve as the operating power source or usage power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0116] 2 and 3 , FIG2 is an exploded view of a battery 100 according to some embodiments of the present invention, and FIG3 is a schematic diagram of a battery cell 20 according to some embodiments of the present invention. The battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is accommodated in the housing 10 .

[0117] The housing 10 is used to provide assembly space for the battery cells 20 and can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12. The first housing body 11 and the second housing body 12 cover each other, and the first housing body 11 and the second housing body 12 jointly define an assembly space for accommodating the battery cells 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure. The first housing body 11 covers the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define the assembly space. The first housing body 11 and the second housing body 12 can also be hollow structures with one end open, and the open side of the first housing body 11 covers the open side of the second housing body 12.

[0118] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid or a cube, etc. For example, in FIG2 , the box body 10 is in the shape of a cuboid.

[0119] In the battery 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel configurations within the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 10.

[0120] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20 .

[0121] In the embodiment of the present application, the battery cell 20 may be a secondary battery cell. A secondary battery cell refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell 20 is discharged.

[0122] The battery cell 20 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., which is not limited in the embodiments of the present application.

[0123] The battery cell 20 may be in a cylindrical, prism, or other shapes. For example, in FIG3 , the battery cell 20 is a square-shell battery.

[0124] As shown in Figure 3, in some embodiments, a battery cell 20 further includes a housing 21 and a cover 22. The housing 21 defines a storage space, within which the electrode assembly 23 is housed. An opening is formed at one end of the storage space, through which the electrode assembly 23 enters the housing 21. The cover 22 seals the opening. The shape of the cover 22 can be adapted to match the shape of the housing 21 to fit within the housing 21. The cover 22 is typically made of a material with a certain degree of hardness and strength (such as aluminum alloy). This prevents deformation when subjected to compression or collision, providing the battery cell 20 with greater structural strength and improved reliability. The cover 22 may be provided with functional components such as electrode lead-outs. The electrode lead-outs can be used to electrically connect to the electrode assembly 23 for transferring electrical energy to or from the battery cell 20. In some embodiments, the cover 22 may also be provided with a pressure relief mechanism 221 for relieving internal pressure in the battery cell 20 when the internal pressure or temperature reaches a threshold. The cover 22 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member (not shown) can be provided inside the cover 22 to isolate the electrical connection components within the housing 21 from the end caps to reduce the risk of short circuits. Exemplary materials include plastic, rubber, etc.

[0125] The cover 22 may further be provided with a liquid injection hole 222 and a sealing nail 223 . The liquid injection hole 222 is used to inject electrolyte into the interior of the battery cell 20 . The sealing nail 223 is used to seal the liquid injection hole 222 .

[0126] A protective member 224 may also be provided on the surface of the cover 22 facing away from the shell 21 . The covering member covers the surface of the cover 22 facing away from the shell 21 and can provide heat insulation and insulation.

[0127] The housing 21 is a component that cooperates with the cover 22 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 21 and end caps can be separate components. An opening can be provided in the housing 21, and the cover 22 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the cover 22 and housing 21 can be integrated. Specifically, the cover 22 and housing 21 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 21 needs to be enclosed, the cover 22 is placed over the housing 21. The housing 21 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylinder, or a hexagonal prism. Specifically, the shape of the housing 21 can be determined based on the specific shape and size of the electrode assembly 23. The housing 21 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0128] As shown in FIG3 , in some embodiments, the battery cell 20 includes an electrode assembly 23, a positive electrode lead-out portion 24, a positive electrode connection assembly 25, a negative electrode lead-out portion 26, and a negative electrode connection assembly 27; the electrode assembly 23 includes a positive electrode sheet 231 and a negative electrode sheet 232; the positive electrode connection assembly 25 electrically connects the positive electrode sheet 231 and the positive electrode lead-out portion 24, and the positive electrode lead-out portion 24 is used to electrically connect to components outside the battery cell 20; the negative electrode connection assembly 27 electrically connects the negative electrode sheet 232 and the negative electrode lead-out portion 26, and the negative electrode lead-out portion 26 is used to electrically connect to components outside the battery cell 20; wherein the minimum overcurrent cutoff value of the positive electrode connection assembly 25 is The area is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion 24, the melting point of the positive electrode connection assembly 25 is smaller than the melting point of the negative electrode connection assembly 27, the minimum flow cross-sectional area of ​​the positive electrode connection assembly 25 is A1, in mm2, the minimum flow cross-sectional area of ​​the negative electrode connection assembly 27 is A2, in mm2, the melting point of the positive electrode connection assembly 25 is B1, in °C, the melting point of the negative electrode connection assembly 27 is B2, in °C, the resistivity of the positive electrode connection assembly 25 is C1, in Ωm, the resistivity of the negative electrode connection assembly 27 is C2, in Ωm, satisfying: A1<A2*(B2 / B1)*(C1 / C2).

[0129] The electrode assembly 23 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 20, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0130] The positive electrode sheet 231 may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0131] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0132] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0133] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for the battery 100 may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523), LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211), LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi0.85Co0.15Al0.05O2) and at least one of their modified compounds.

[0134] The negative electrode sheet 232 may include a negative current collector.

[0135] As an example, the negative electrode current collector can be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium can be used. The metal foam can be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0136] As an example, the negative electrode sheet 232 may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0137] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0138] As an example, the negative electrode active material may adopt the negative electrode active material for the battery cell 20 that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for the battery 100 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0139] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0140] The separator may be a separator membrane, and the material of the separator membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane may be a single-layer film or a multi-layer composite film. When the separator membrane is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0141] The positive electrode connector assembly 25 is a conductive structure located within the housing 21 that electrically connects the positive electrode sheet 231 and the positive electrode lead 24. The positive electrode lead 24 is electrically connected to the positive electrode sheet 231 via the positive electrode connector assembly 25. The positive electrode lead 24 can be disposed on the cover 22. The positive electrode lead 24 disposed on the cover 22 can also be referred to as a positive terminal or a positive electrode post. The positive electrode lead 24 and the cover 22 can be connected by welding, riveting, or other components. The materials of the positive electrode lead 24 include, but are not limited to, aluminum and copper.

[0142] In some embodiments, the housing 21 can serve as the positive electrode lead-out portion 24, that is, the positive electrode sheet 231 is electrically connected to the housing 21 via the positive electrode connection assembly 25. The positive electrode connection assembly 25 can be made of the same material or a variety of different materials.

[0143] The negative electrode connector assembly 27 is a conductive structure located within the housing 21 that electrically connects the negative electrode sheet 232 and the negative electrode lead 26. The negative electrode lead 26 is electrically connected to the negative electrode sheet 232 via the negative electrode connector assembly 27. The negative electrode lead 26 can be disposed on the cover 22. The negative electrode lead 26 disposed on the cover 22 may also be referred to as a negative terminal or a negative electrode post. The negative electrode lead 26 and the cover 22 may be connected by welding, riveting, or other methods. The negative electrode lead 26 may be made of materials including, but not limited to, aluminum and copper.

[0144] In some embodiments, the housing 21 can serve as the negative electrode lead-out portion 26, i.e., the negative electrode sheet 232 is electrically connected to the housing 21 via the negative electrode connector 27. In embodiments where the housing 21 serves as the positive electrode lead-out portion 24, the negative electrode lead-out portion 26 can be disposed on the cover 22. In embodiments where the housing 21 serves as the negative electrode lead-out portion 26, the positive electrode lead-out portion 24 can be disposed on the cover 22. For example, in embodiments where the battery cell 20 is a cylindrical battery 100, the housing 21 can serve as the negative electrode lead-out portion 26, and the positive electrode lead-out portion 24 can be disposed on the cover 22.

[0145] Of course, the positive lead portion 24 and the negative lead portion 26 may both be provided on the cover 22 (shown in FIG3 ). For example, in an embodiment where the battery cell 20 is a square-cased battery 100 , the positive lead portion 24 and the negative lead portion 26 are both provided on the cover 22 .

[0146] In the embodiment where the positive electrode lead-out portion 24 is disposed on the cover 22, the positive electrode lead-out portion 24 may extend partially into the housing 21, partially extend to the side of the cover 22 facing away from the housing 21, and partially pass through the through-hole in the cover 22. The minimum diameter of the positive electrode lead-out portion 24 is D1, in mm, and the flow cross-section of the positive electrode lead-out portion 24 = π*(D1 / 2)2. For example, as shown in Figures 4 and 5, the positive electrode lead-out portion 24 is riveted to the cover 22 and includes a first portion 241, a second portion 242, and a third portion 243. The first portion 241 and the third portion 243 are respectively connected to the ends of the second portion 242. The first portion 241 and the third portion 243 are respectively located on opposite sides of the cover 22 in the thickness direction. The first portion 241 is located on the side of the cover 22 facing away from the housing 21, and the third portion 243 is located on the side of the cover 22 facing the housing 21. The first portion 241 is a rectangular structure, the second portion 242 is a cylindrical structure, and the third portion 243 can be cylindrical or rectangular. The cross-sectional area of ​​the first portion 241 is greater than the cross-sectional area of ​​the second portion 242, and the cross-sectional area of ​​the third portion 243 is greater than the cross-sectional area of ​​the second portion 242. The second portion 242 is the portion with the smallest cross-sectional area of ​​the positive electrode lead-out portion 24. Taking the cylindrical second portion 242 as an example, the diameter of the second portion 242 is the minimum diameter D1 of the positive electrode lead-out portion 24, in mm, and the cross-sectional area of ​​the second portion 242 is the flow cross-sectional area of ​​the positive electrode lead-out portion 24, that is, the cross-sectional area of ​​the second portion 242 = π*(D1 / 2)2.

[0147] As shown in Figures 6 and 7, the positive electrode lead-out portion 24 is connected to the cover 22 and includes a first portion 241 and a second portion 242. The first portion 241 is connected to one end of the second portion 242. The first portion 241 is located on the side of the cover 22 facing away from the housing 21. The first portion 241 and the second portion 242 are both cylindrical structures. The smallest diameter of the positive electrode lead-out portion 24 is located at the end of the first portion 241 facing away from the second portion 242.

[0148] The negative electrode connection assembly 27 can be manufactured using the same material or a variety of different materials.

[0149] Components external to the battery cells 20 that are electrically connected to the positive and negative lead portions 24, 26 include, but are not limited to, a busbar assembly and electrical connection interfaces for electrical equipment. The busbar assembly enables electrical connection between multiple battery cells 20. Electrical connection interfaces for electrical equipment, when electrically connected to the positive and negative lead portions 24, 26, can provide power to the electrical equipment.

[0150] The melting region R1 is the melting area of ​​the positive electrode connection assembly 25 when the battery cell 20 is short-circuited and the temperature rises to a certain value. The melting region R1 may be the location where the current flow cross-sectional area of ​​the positive electrode connection assembly 25 is the smallest.

[0151] The melting point is the temperature at which a solid changes (melts) from a solid to a liquid state. Specifically, B1 is the temperature at which the positive electrode connector assembly 25 melts from a solid to a liquid state, and B2 is the temperature at which the negative electrode connector assembly 27 melts from a solid to a liquid state.

[0152] Resistivity can represent the resistance characteristics of the positive electrode connection component 25 and the negative electrode connection component 27. When B1 < B2, A1 < A2*(B2 / B1)*(C1 / C2), which can make the melting point at the positive electrode connection component 25. For example, when the material of the positive electrode connection component 25 is aluminum and the material of the negative electrode connection component 27 is copper, B1 = 660, B2 = 1083, C1 = 2.83*(10^-8), C2 = 1.75*(10^-8), A1 = 44.8, A2 = 20.8, A2*(B2 / B1)*(C1 / C2) = 55.19, satisfying A1 <A2*(B2 / B1)*(C1 / C2)。

[0153] When the material of the positive electrode connection component 25 is aluminum and the material of the negative electrode connection component 27 is nickel, B1=660, B2=1452, C1=2.83*(10^-8), C2=6.84*(10^-8), A1=12, A2=14, A2*(B2 / B1)*(C1 / C2)=12.74, satisfying A1 <A2*(B2 / B1)*(C1 / C2)。

[0154] The melting point of the positive electrode connection assembly 25 is lower than the melting point of the negative electrode connection assembly 27. The minimum flow cross-sectional area of ​​the positive electrode connection assembly is A1, the minimum flow cross-sectional area of ​​the negative electrode connection assembly 27 is A2, the melting point of the positive electrode connection assembly 25 is B1, the melting point of the negative electrode connection assembly 27 is B2, and the resistivity C1 of the positive electrode connection assembly 25 satisfies: A1<A2*(B2 / B1)*(C1 / C2). Therefore, when the battery cell 20 is short-circuited, the fuse position occurs in the positive electrode connection assembly 25. In this way, when the short-circuit path of the battery cell 20 is melted, the overall temperature of the battery cell 20 is lower, thereby reducing the risk of fire, explosion and other problems in the battery cell 20 and improving the reliability of the battery cell 20.

[0155] (B2 / B1)*(C1 / C2) can be greater than 1, less than 1, or equal to 1. Since the melting point B1 of the positive electrode connector assembly 25 is less than the melting point B2 of the negative electrode connector assembly 27, when (B2 / B1)*(C1 / C2)≥1, when the battery cell 20 short-circuits, the melting may occur at the positive electrode connector assembly 25, and the positive electrode connector assembly 25 can also have a larger current capacity, which is conducive to fast charging.

[0156] In some embodiments, A1≤2.5A2.

[0157] For example, A1 can be equal to 0.3A2, 0.5A2, 0.7A2, A2, 1.2A2, 1.7A2, 1.9A2, 2A2, 2.5A2, etc.

[0158] A1≤2.5A2, so that the positive electrode connection assembly 25 has a better current carrying capacity, and also enables the positive electrode connection assembly 25 to melt when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the risk of fire, explosion and other problems, and improving the reliability of the battery cell 20.

[0159] In some embodiments, A1≤2.3A2.

[0160] For example, A1 can be equal to 0.1A2, 0.3A2, 0.9A2, 1.3A2, 1.7A2, 1.8A2, 2.1A2, 2.2A2, etc.

[0161] A1≤2.3A2, so that the positive electrode connection assembly 25 has a better current carrying capacity, meeting more usage requirements, and also enables the positive electrode connection assembly 25 to melt when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the risk of fire, explosion and other problems, and improving the reliability of the battery cell 20.

[0162] In some embodiments, A1≤1.5A2.

[0163] For example, A1 can be equal to 0.2A2, 0.4A2, 0.6A2, 1.1A2, 1.2A2, 1.4A2, 1.5A2, etc.

[0164] A1≤1.5A2, so that when the battery cell 20 is short-circuited, the positive electrode connection assembly 25 can be melted, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell 20 has better reliability.

[0165] In some embodiments, A1<A2.

[0166] For example, A1 can be equal to 0.15A2, 0.25A2, 0.35A2, 0.45A2, 0.55A2, 0.65A2, 0.75A2, 0.85A2, etc.

[0167] When A1 is less than A2, and the melting point of the melting zone is lower than the melting point of the negative electrode connection assembly 27, when the battery cell 20 is short-circuited, the positive electrode connection assembly 25 can be melted, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell 20 has better reliability.

[0168] In some embodiments, the positive electrode ear 251 includes a plurality of positive electrode ear portions 2511 arranged in a stacked manner, the negative electrode connection assembly 27 includes a negative electrode ear 271, the negative electrode ear 271 is connected to the negative electrode sheet 232, and the negative electrode ear 271 includes a plurality of negative electrode ear portions 2711 arranged in a stacked manner; the number of positive electrode ear portions 2511 is less than the number of negative electrode ear portions 2711.

[0169] Multiple means two or more.

[0170] Multiple positive electrode tabs 2511 are stacked together to form the positive electrode tab 251, and multiple negative electrode tabs 2711 are stacked together to form the negative electrode tab 271. Each negative electrode tab 2711 and the negative electrode current collector of the negative electrode sheet 232 can be integrally formed. Each negative electrode tab 2711 and the positive electrode current collector of the negative electrode sheet 232 can also be separate components and connected together via welding, conductive adhesive, or other methods. The thickness of the positive electrode tab and the thickness of the negative electrode tab 2711 can be the same or different.

[0171] The number of positive electrode ears 2511 is smaller than the number of negative electrode ears 271 , so the thickness of the positive electrode ear 251 formed by stacking multiple positive electrode ears 2511 can be smaller than the thickness of the negative electrode ear 271 formed by stacking multiple negative electrode ears 2711 .

[0172] The number of the positive electrode ears 2511 is smaller than the number of the negative electrode ears 2711 , which is beneficial for the negative electrode ears 271 to have a larger flow cross-sectional area, so that the negative electrode connection assembly 27 is less likely to melt.

[0173] For another example, in some embodiments, the negative electrode connection assembly 27 includes a negative electrode tab 271 , the negative electrode tab 271 is connected to the negative electrode sheet 232 , and the width of the positive electrode tab 251 is smaller than the width of the negative electrode tab 271 .

[0174] In an embodiment where the negative electrode tab 271 includes a plurality of stacked negative electrode tabs 2711, and the negative electrode tabs 2711 and the negative electrode current collector of the negative electrode sheet 232 are integrally formed, the negative electrode tab 2711 has two second side surfaces 2712 arranged opposite each other along its width. Along the width of the negative electrode sheet 232, the negative electrode current collector of the negative electrode sheet 232 has a second end surface 2321. The second end surface 2321 and each second side surface 2712 are connected by a second curved surface 2713. The second curved surface 2713 and the second side surface 2712 are connected at a second connection position Q2. The width direction of the negative electrode tab 2711 is parallel to the width direction X1 of the positive electrode tab. The width direction of the negative electrode sheet 232 is parallel to the width direction Y1 of the positive electrode sheet.

[0175] As shown in Figures 8 and 9, in an embodiment where each negative electrode ear portion 2711 has the same width, after multiple negative electrode ears 2711 are stacked together to form a positive electrode ear 251, the width L2 of the negative electrode ear portion 2711 is the width of the negative electrode ear 271. The width L2 of the negative electrode ear portion 2711 is the distance between the two second connection positions Q2 that are farthest apart along the width direction of the negative electrode ear portion 2711. The sum of the thicknesses h2 of all negative electrode ears 2711 is the thickness of the negative electrode ear 271. The flow cross-sectional area of ​​the negative electrode ear 271 is the product of the width of the negative electrode ear 271 and the thickness of the negative electrode ear 271, that is, the product of the width of one negative electrode ear portion 2711 and the sum of the thicknesses of all negative electrode ears 2711.

[0176] As shown in Figures 10 and 11, in embodiments where multiple negative electrode lugs 2711 have different widths, after the multiple negative electrode lugs 2711 are stacked together to form a negative electrode lug 271, the width of the negative electrode lug 271 is the distance between the two second connection locations Q2 that are farthest apart in the width direction of the negative electrode lug 271. The thickness of the negative electrode lug 271 is the sum of the thicknesses h2 of all negative electrode lugs 2711, where h2 is the thickness of one negative electrode lug 2511. The flow cross-sectional area of ​​the negative electrode lug 271 is the product of the width of the negative electrode lug 271 and the thickness of the negative electrode lug 271. The flow cross-sectional area of ​​the negative electrode lug 271 is the product of the width of the negative electrode lug 271 and the thickness of the negative electrode lug 271.

[0177] It should be noted that FIG8 to FIG11 all show the case where the thickness of each negative electrode ear portion 2711 is the same.

[0178] As shown in Figures 3 and 8 to 11, in some embodiments, the positive electrode connection assembly 25 includes a positive electrode ear 251, which is connected to the positive electrode sheet 231, and the flow cross-sectional area of ​​the positive electrode ear 251 is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion 252.

[0179] That is, when the battery cell 20 is short-circuited, the fuse is generated at the positive electrode tab 251. The flow area A1 of the positive electrode connection assembly 25 is the flow area of ​​the positive electrode tab 251.

[0180] The positive electrode tab 251 includes a plurality of stacked positive electrode tabs 2511. The plurality of positive electrode tabs 2511 are stacked and welded together to form the positive electrode tab 251, for example, by molding. Each positive electrode tab 2511 and the positive electrode current collector of the positive electrode sheet 231 can be integrally formed. Alternatively, each positive electrode tab 2511 and the positive electrode current collector of the positive electrode sheet 231 can be separate components and connected together by welding, conductive adhesive, or other methods.

[0181] In an embodiment where the positive electrode ear 2511 and the positive electrode current collector of the positive electrode sheet 231 are integrally formed, the positive electrode ear 2511 has two first side surfaces 2512 arranged opposite each other along the width direction X1 of the positive electrode ear. Along the width direction Y1 of the positive electrode sheet, the positive electrode current collector of the positive electrode sheet 231 has a first end surface 2311. The first end surface 2311 and each first side surface 2512 are connected by a first curved surface 2513. The first curved surface 2513 and the first side surface 2512 are connected at a first connection location Q1. The width direction X1 of the positive electrode ear can be perpendicular to the width direction Y1 of the positive electrode sheet. The width direction Y1 of the positive electrode sheet is parallel to the extension direction of the winding axis of the electrode assembly.

[0182] As shown in Figures 8 and 9 , in an embodiment where each positive electrode ear portion 2511 has the same width, after multiple positive electrode ears 2511 are stacked together to form a positive electrode ear 251, the width L1 of the positive electrode ear portion 2511 is the width of the positive electrode ear 251. The width L1 of the positive electrode ear portion 2511 is the distance between the two first connection positions Q1 along the width direction X1 of the positive electrode ear portion. The sum of the thicknesses h1 of all positive electrode ears 2511 is the thickness of the positive electrode ear 251. The flow cross-sectional area of ​​the positive electrode ear 251 is the product of the width of the positive electrode ear 251 and the thickness of the positive electrode ear 251, that is, the product of the width of the positive electrode ear portion 2511 and the sum of the thicknesses of all positive electrode ears 2511. In the embodiment where the melting zone R1 is located at the positive ear 251, A1 = the product of the width of the positive ear 2511 and the sum of the thicknesses of all the positive ears 2511, that is, A1 = L1*h1*N, where N is the number of positive ears 2511, N is a natural number greater than or equal to 1, and h1 is the thickness of one positive ear 2511.

[0183] As shown in Figures 10 and 11, in embodiments where multiple positive electrode tabs 2511 have different widths, after the multiple positive electrode tabs 2511 are stacked together to form the positive electrode tab 251, the width of the positive electrode tab 251 is the distance between the two first connection locations Q1 that are farthest apart in the width direction X1 of the positive electrode tab. The thickness of the positive electrode tab 251 is the sum of the thicknesses h1 of all positive electrode tabs 2511. The flow cross-sectional area of ​​the positive electrode tab 251 is the product of the width of the positive electrode tab 251 and the thickness of the positive electrode tab 251. In embodiments where the fuse zone is provided in the positive electrode tab 251, A1 = the product of the width of the positive electrode tab 251 and the thickness of the positive electrode tab 251, that is, A1 = L1*h1*N, where N is the number of positive electrode tabs 2511 and is a natural number greater than or equal to 1.

[0184] As shown in Figures 8 and 10, when a fuse occurs in the positive tab 251, the tab 251 has a fuse region R1 that fuses during a short circuit. Along the width direction Y1 of the positive electrode sheet, the fuse region R1 is located between the line connecting the two farthest first connection locations Q1 and the end of the positive tab 251 facing away from the positive electrode sheet.

[0185] It should be noted that FIG8 to FIG11 all show the case where the thickness of each positive electrode ear portion 2511 is the same.

[0186] The cross-sectional area of ​​the positive electrode ear 252 is smaller than the cross-sectional area of ​​the positive electrode lead-out portion 24. When a short circuit occurs, the melting can occur at the positive electrode ear 251. If the melting occurs at the positive electrode connection assembly 25, the structure of the positive electrode ear 251 itself can be used to achieve melting at the positive electrode connection assembly 25 when the battery cell 20 is short-circuited, making the structure of the battery cell 20 simpler.

[0187] In the embodiment where the melting occurs at the positive electrode tab 251 , the rated capacity of the battery cell 20 is W, in Ah, and satisfies A1 / W≥0.15.

[0188] The rated capacity of the battery cell 20 may be the capacity of the battery cell 20 when the battery cell 20 is fully charged (100% SOC). The rated capacity test may refer to the GBT 31486-2015 test.

[0189] Illustratively, A1 / W may be 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0190] A1 / W≥0.15, so that the positive electrode ear 251 has better current carrying capacity, and can also make the temperature rise at the positive electrode ear 251 larger, reducing the risk of the negative electrode connection assembly 27 melting when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell 20 has better reliability.

[0191] In some embodiments, the positive electrode tab 251 is connected to the positive electrode lead-out portion 24 .

[0192] The positive electrode tab 251 is directly connected to the positive electrode lead-out portion 24. The positive electrode tab 251 and the positive electrode lead-out portion 24 can be connected by welding, conductive adhesive, etc.

[0193] The positive electrode tab 251 is connected to the positive electrode lead-out portion 24 , and the positive electrode connection assembly 25 is not provided with the positive electrode adapter 252 , which can simplify the structure of the battery cell 20 .

[0194] In the embodiment where the melting occurs at the positive ear 251, the number of positive ear portions 2511 is smaller than the number of negative ear portions 2711, which is beneficial for the cross-sectional area of ​​the positive ear 251 to be smaller than the cross-sectional area of ​​the negative ear 271, thereby achieving that the flow cross-sectional area of ​​the melting zone located at the positive ear 251 is smaller than the flow cross-sectional area of ​​the negative ear 271, which is beneficial for the positive electrode connection assembly 25 to be melted when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell 20 has better reliability.

[0195] In the embodiment where the melting occurs at the positive ear 251, the width of the positive ear 251 is smaller than the width of the negative ear 271, which is beneficial for the cross-sectional area of ​​the positive ear 251 to be smaller than the cross-sectional area of ​​the negative ear 271, thereby achieving that the flow cross-sectional area of ​​the melting zone located at the positive ear 251 is smaller than the flow cross-sectional area of ​​the negative ear 271. This is beneficial for the positive electrode connection assembly 25 to be melted when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of fire, explosion and other problems, so that the battery cell 20 has better reliability.

[0196] As shown in Figures 3 and 12 to 17, in the embodiment in which the melting zone is provided at the positive electrode ear 251, the positive electrode connection assembly 25 further includes a positive electrode adapter 252, which connects the positive electrode ear 251 and the positive electrode lead-out portion 24; the positive electrode adapter 252 includes a first welding area 252a, a second welding area 252b and a transition connection portion 252c, the first welding area 252a is connected to the positive electrode ear 251, the second welding area 252b is connected to the positive electrode lead-out portion 24, and the transition connection portion 252c is connected between the first welding area 252a and the second welding area 252b; the minimum cross-sectional area of ​​the transition connection portion 252c is greater than or equal to the minimum cross-sectional area of ​​the first welding area 252a, and / or the minimum cross-sectional area of ​​the transition connection portion 252c is greater than or equal to the minimum cross-sectional area of ​​the second welding area 252b.

[0197] The material of the positive electrode adapter 252 can be the same as or different from that of the positive electrode tab 251. The positive electrode tab 251 and the positive electrode lead 24 are electrically connected via the positive electrode adapter 252. The positive electrode tab 251 and the positive electrode adapter 252 can be connected by welding, conductive adhesive, or other methods. The positive electrode lead 24 and the positive electrode adapter 252 can be connected by welding, conductive adhesive, or other methods. The cross-sectional area of ​​the positive electrode tab 251 is smaller than that of the positive electrode adapter 252.

[0198] The first welding area 252a is a weld mark area formed by welding the positive electrode tab 251 and the positive electrode adapter 252. The second welding area 252b is a weld mark area formed by welding the positive electrode adapter 252 and the positive electrode lead-out portion 24.

[0199] The positive electrode tab 251 and the positive electrode lead 24 are connected via the positive electrode adapter 252, facilitating electrical connection between the positive electrode tab 251 and the positive electrode lead 24, thereby improving the current handling capacity of the positive electrode connection assembly 25. The cross-sectional area of ​​the transition connection 252c is greater than or equal to the cross-sectional area of ​​the first welding region 252a, and / or the cross-sectional area of ​​the transition connection 252c is greater than or equal to the cross-sectional area of ​​the second welding region 252b. The larger cross-sectional area of ​​the transition connection 252c improves the current handling capacity of the transition connection 252c, reduces the temperature rise of the positive electrode adapter 252, and reduces the risk of the positive electrode adapter 252 fusing.

[0200] As shown in Figures 3 and 12-14, in some embodiments, the positive electrode connection assembly 25 also includes a positive electrode adapter 252 and a positive electrode ear 251, the positive electrode ear 251 is connected to the positive electrode sheet 231, the positive electrode adapter 252 connects the positive electrode ear 251 and the positive electrode lead-out portion 24, the minimum flow cross-sectional area of ​​the positive electrode adapter 252 is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion 24, and the minimum flow cross-sectional area of ​​the positive electrode adapter 252 is smaller than the flow cross-sectional area of ​​the positive electrode ear 251.

[0201] That is, when a battery cell 20 short-circuits, the positive electrode adapter 252 fuses. A fuse zone forms where the positive electrode adapter 252 is not connected to the positive tab 251 or the positive electrode lead 24. The fuse zone can have a current-carrying cross-sectional area equal to the minimum current-carrying cross-sectional area of ​​the positive electrode adapter 252 or a region a certain distance from the location where the positive electrode adapter 252 has the minimum current-carrying cross-sectional area.

[0202] As shown in Figures 14 and 15, the cross-sectional area of ​​the positive electrode adapter 252 can be measured by observing the area of ​​the positive electrode adapter 252 that is not connected to the positive electrode tab 251 and the positive electrode lead 24, where the cross-sectional area is smaller. The cross-sectional area of ​​the positive electrode adapter 252 is then measured in this area. The width of the positive electrode adapter 252 is L3, and the thickness of the positive electrode adapter 252 is H1. The cross-sectional area of ​​the positive electrode adapter 252 = L3 * H1. In the embodiment where the fuse zone is formed in the positive electrode adapter 252, A1 = L3 * H1. The width dimension of the positive electrode adapter 252 is smaller than the length dimension of the positive electrode adapter 252. The width, length, and thickness of the positive electrode adapter 252 are perpendicular to each other. For positive electrode adapters 252 of different structures, the width direction of the positive electrode adapter 252 can be different. Therefore, the width L3 of the positive electrode adapter 252 is measured in different directions. As shown in Figure 17, the width direction of the positive electrode adapter 252 is along the left-right direction in the figure. The width direction of the positive electrode sheet 231 in Figure 18 is along the up-down direction in the figure.

[0203] The minimum flow cross-sectional area of ​​the positive electrode adapter 252 is smaller than the flow cross-sectional area of ​​the positive electrode ear 251, which means that when the battery cell 20 is short-circuited, the flow cross-sectional area of ​​the melting position of the positive electrode adapter 252 is smaller than the flow cross-sectional area of ​​the melting area of ​​the positive electrode ear 251 when the battery cell 20 is not provided with the positive electrode adapter 252, so that when the positive electrode connection assembly 25 includes the positive electrode ear 251 and the positive electrode adapter 252, the melting position occurs at the positive electrode adapter 252.

[0204] The positive electrode tab 251 and the positive electrode lead 24 are connected via the positive electrode adapter 252, facilitating electrical connection between the positive electrode tab 251 and the positive electrode lead 24 and improving the current carrying capacity of the positive electrode connector assembly 25. A fuse zone is provided on the positive electrode adapter 252. If a short circuit occurs in the battery cell 20, the positive electrode adapter will fuse, thereby severing the short-circuit path. This will cause the positive electrode connector assembly 25 to fuse, thereby lowering the overall temperature of the battery cell 20 when the short-circuit path is severed. This reduces the risk of fire and explosion, and enhances the reliability of the battery cell 20.

[0205] In an embodiment where the minimum flow cross-sectional area of ​​the positive electrode adapter 252 is smaller than the flow cross-sectional area of ​​the positive electrode tab 251, the positive electrode adapter 252 includes a first welding area 252a, a second welding area 252b and a transition connection portion 252c, the first welding area 252a is connected to the positive electrode tab 251, the second welding area 252b is connected to the positive electrode lead-out portion 24, and the transition connection portion 252c is connected between the first welding area 252a and the second welding area 252b; the cross-sectional area of ​​the transition connection portion 252c is greater than or equal to the minimum cross-sectional area of ​​the first welding area 252a, and / or the cross-sectional area of ​​the transition connection portion 252c is greater than or equal to the minimum cross-sectional area of ​​the second welding area 252b.

[0206] The cross-sectional area of ​​the transition portion 252c is the cross-sectional area at L3 in Figures 15, 17, and 18. When the transition portion 252c has multiple portions with different cross-sectional areas, the portion with the smallest cross-sectional area is used as the cross-sectional area of ​​the transition portion 252c.

[0207] The transition connection portion 252c of the positive electrode adapter 252 has the smallest cross-sectional area. In the embodiment of the positive electrode adapter 252, when short circuit occurs, the melting region R1 is located in the transition connection portion 252c, that is, the melting region R1 is located in the area between the first welding region 252a and the second welding region 252b.

[0208] The minimum cross-sectional area of ​​the transition connection portion 252c is greater than or equal to the minimum cross-sectional area of ​​the first welding area, and / or the minimum cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the second welding area, which is beneficial for the positive electrode adapter to have a higher current capacity.

[0209] In the embodiment where the fuse region R1 is disposed on the positive electrode adapter 252 , the rated capacity of the battery cell 20 is W, in Ah, and satisfies A1 / W≥0.2.

[0210] Illustratively, A1 / W may be 0.1, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, etc.

[0211] This allows the positive electrode adapter 252 to have better current-carrying capacity and also allows the temperature rise at the positive electrode adapter 252 to be greater, thereby reducing the risk of the negative electrode connection assembly 27 melting when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of problems such as fire and explosion, so that the battery cell 20 has better reliability.

[0212] As shown in FIG. 14 , in some embodiments, the thickness of at least a portion of the positive electrode adapter 252 is H1 , satisfying 1.0 mm ≤ H1 ≤ 1.5 mm.

[0213] The thickness of the positive electrode adapter 252 may satisfy 1.0 mm ≤ H1 ≤ 1.5 mm at any position, or the thickness of only a portion of the positive electrode adapter 252 may satisfy 1.0 mm ≤ H1 ≤ 1.5 mm.

[0214] Illustratively, H1 may be 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc.

[0215] The thickness H1 of at least part of the positive electrode adapter 252 satisfies 1.0mm≤H1≤1.5mm, which is beneficial for the positive electrode adapter 252 to have better current flow capacity, is beneficial for improving the formation of the fast-charging battery 100, and is also convenient for the positive electrode ear 251 and the positive electrode lead-out portion 24 to be connected to the positive electrode adapter 252 respectively, which is beneficial for improving the connection stability between the positive electrode ear 251 and the positive electrode adapter 252 and the connection stability between the positive electrode lead-out portion 24 and the positive electrode adapter 252.

[0216] As shown in Figures 14 to 18, in some embodiments, the positive electrode adapter 252 includes a first connecting portion 2521 and a second connecting portion 2522. The first connecting portion 2521 is connected to the positive electrode ear 251, and the second connecting portion 2522 is connected to the positive electrode lead-out portion 24. The thickness of the first connecting portion 2521 is greater than or equal to the thickness of the second connecting portion 2522. The thickness of the first connecting portion 2521 is H1, satisfying 1.0mm≤H1≤1.5mm.

[0217] The first connecting portion 2521 and the positive electrode tab 251 can be connected by welding, conductive adhesive, or other means to achieve electrical connection between the positive electrode adapter 252 and the positive electrode tab 251. The second connecting portion 2522 and the positive electrode lead 24 can be connected by welding, conductive adhesive, or other means to achieve electrical connection between the positive electrode adapter 252 and the positive electrode lead 24. In embodiments where the fuse region is provided on the positive electrode adapter 252, the fuse region is provided on the positive electrode adapter 252 and is located between the first connecting portion 2521 and the second connecting portion 2522. The first welding region 252a is a portion of the first connecting portion 2521. The second welding region 252b is a portion of the second connecting portion 2522.

[0218] The thickness H1 of the first connection portion 2521 may be 1.05 mm, 1.15 mm, 1.25 mm, 1.35 mm, 1.45 mm, 1.47 mm, 1.5 mm, etc.

[0219] The thickness of the first connecting portion 2521 is greater than that of the second connecting portion 2522 , which can improve the current carrying capacity of the positive electrode adapter 252 and improve the welding quality between the positive electrode lead-out portion 24 and the positive electrode adapter 252 .

[0220] In some embodiments, the positive electrode tab 251 is made of aluminum; and / or the positive electrode adapter 252 is made of aluminum.

[0221] The positive electrode tab 251 may be made of aluminum, and the positive electrode adapter 252 may be made of a material other than aluminum, such as nickel. Alternatively, the positive electrode adapter 252 may be made of aluminum, and the positive electrode tab 251 may be made of a material other than aluminum, such as nickel. Alternatively, both the positive electrode tab 251 and the positive electrode adapter 252 may be made of aluminum to ensure better connection stability between the positive electrode tab 251 and the positive electrode adapter 252.

[0222] The material of the positive electrode ear 251 and / or the positive electrode adapter 252 is aluminum, which not only makes the positive electrode connection assembly 25 have better current carrying capacity, but also makes the positive electrode adapter assembly easier to melt, so that when the battery cell 20 is short-circuited, the positive electrode connection assembly 25 can be melted, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path of the battery cell 20 is cut off, thereby reducing the occurrence of fire, explosion and other problems, so that the battery cell 20 has better reliability.

[0223] As shown in Figures 3 and 12 to 18, in some embodiments, the negative electrode connection assembly 27 further includes a negative electrode adapter 272 and a negative electrode ear 271. The negative electrode ear 271 is connected to the negative electrode sheet 232, and the negative electrode adapter 272 connects the negative electrode ear 271 and the negative electrode lead-out portion 26.

[0224] The material of the negative electrode adapter 272 can be the same as that of the negative electrode tab 271. The negative electrode tab 271 and the negative electrode lead 26 are electrically connected via the negative electrode adapter 272. The negative electrode tab 271 and the negative electrode adapter 272 can be connected by welding, conductive adhesive, or the like. The negative electrode lead 26 and the negative electrode adapter 272 can also be connected by welding, conductive adhesive, or the like.

[0225] The negative electrode tab 271 and the negative electrode lead-out portion 26 are connected via the negative electrode adapter 272 , which facilitates the electrical connection between the negative electrode tab 271 and the negative electrode lead-out portion 26 and helps improve the current carrying capacity of the negative electrode connection assembly 27 .

[0226] In some embodiments, the minimum flow cross-sectional area of ​​the negative electrode adapter 272 is greater than the maximum flow cross-sectional area of ​​the negative electrode tab 271 .

[0227] It can be understood that the flow cross-sectional area at any position of the negative electrode adapter 272 is larger than the flow cross-sectional area at any position of the negative electrode tab 271 .

[0228] As shown in Figure 16, the cross-sectional area of ​​the negative electrode adapter 272 can be measured by observing the area of ​​the negative electrode adapter 272 that is not connected to the negative electrode tab 271 and the negative electrode lead 26, where the cross-sectional area is smaller. The cross-sectional area of ​​the negative electrode adapter 272 is then measured in this area. The width of the negative electrode adapter 272 is L4, and the thickness of the negative electrode adapter 272 is H1. The cross-sectional area of ​​the negative electrode adapter 272 = L4 * H2. The width of the negative electrode adapter 272 is smaller than its length. The width, length, and thickness of the negative electrode adapter 272 are perpendicular to each other. Different negative electrode adapter 272 structures can have different width directions. Therefore, the width L4 of the negative electrode adapter 272 is measured in different directions. As shown in Figure 15 , the width direction of the negative electrode adapter 272 is along the left-right direction in the figure. The width direction of the negative electrode sheet 232 in Figure 16 is along the up-down direction in the figure.

[0229] The minimum flow cross-sectional area of ​​the negative electrode adapter is greater than the maximum flow cross-sectional area of ​​the negative electrode ear 271 , so that the flow capacity of the negative electrode adapter 272 is better, which is conducive to the formation of a fast-charging battery 100 .

[0230] In other embodiments, the minimum flow cross-sectional area of ​​the negative electrode tab 271 is greater than the maximum flow cross-sectional area of ​​the negative electrode adapter 272 .

[0231] It can be understood that the flow cross-sectional area at any position of the negative electrode tab 271 is larger than the flow cross-sectional area at any position of the negative electrode adapter 272 .

[0232] The measurement method of the minimum flow cross-sectional area of ​​the negative electrode tab 271 and the maximum flow cross-sectional area of ​​the negative electrode adapter 272 can refer to the aforementioned method for measuring the flow cross-sectional area of ​​the negative electrode tab 271 and the flow cross-sectional area of ​​the negative electrode adapter 272, which will not be repeated here.

[0233] The minimum flow cross-sectional area of ​​the negative electrode tab 271 is larger than the maximum flow cross-sectional area of ​​the negative electrode adapter 272 , which is beneficial for the negative electrode tab 271 to have a better flow capacity.

[0234] As shown in FIG. 14 , in some embodiments, the thickness of at least a portion of the negative electrode adapter 272 is H2 , satisfying 0.6 mm ≤ H2 ≤ 1.0 mm.

[0235] The thickness of the negative electrode adapter 272 may satisfy 0.6 mm ≤ H2 ≤ 1.0 mm at any position, or the thickness of only a portion of the negative electrode adapter 272 may satisfy 0.6 mm ≤ H2 ≤ 1.0 mm.

[0236] Illustratively, H2 may be 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc.

[0237] The thickness H2 of at least part of the negative electrode adapter 272 satisfies 0.6mm≤H2≤1.0mm, which is beneficial for the negative electrode adapter 272 to have better current carrying capacity, is beneficial for forming a fast-charging battery 100, and is also convenient for the negative electrode ear 271 and the negative electrode lead-out portion 26 to be connected to the negative electrode adapter 272 respectively, which is beneficial for improving the connection stability between the negative electrode ear 271 and the negative electrode adapter 272 and the connection stability between the negative electrode lead-out portion 26 and the negative electrode adapter 272.

[0238] As shown in Figures 14 to 18, in some embodiments, the negative electrode adapter 272 includes a third connecting portion 2721 and a fourth connecting portion 2722. The third connecting portion 2721 is connected to the negative electrode ear 271, and the fourth connecting portion 2722 is connected to the negative electrode lead-out portion 26. The thickness of the third connecting portion 2721 is greater than or equal to the thickness of the fourth connecting portion 2722. The thickness of the third connecting portion 2721 is H2, satisfying 0.6mm≤H2≤1.0mm.

[0239] The third connecting portion 2721 and the negative electrode tab 271 can be connected by welding, conductive adhesive, or the like, thereby electrically connecting the negative electrode adapter 272 and the negative electrode tab 271. The fourth connecting portion 2722 and the negative electrode lead 26 can be connected by welding, conductive adhesive, or the like, thereby electrically connecting the negative electrode adapter 272 and the negative electrode lead 26. The thickness H2 of the third connecting portion 2721 can be 0.6 mm, 0.65 mm, 0.75 mm, 0.85 mm, 0.95 mm, 1.0 mm, etc.

[0240] The thickness of the third connecting portion 2721 is greater than that of the fourth connecting portion 2722 , which can improve the current carrying capacity of the negative electrode adapter 272 and improve the welding quality between the negative electrode lead-out portion 26 and the negative electrode adapter 272 .

[0241] In some embodiments, the minimum flow cross-sectional area of ​​the positive electrode adapter assembly is smaller than the minimum flow cross-sectional area of ​​the negative electrode tab 271 .

[0242] The minimum cross-sectional area of ​​the positive electrode adapter assembly 25 can be located at the positive electrode ear 251 of the positive electrode connection assembly 25, so that the short circuit occurs at the positive electrode ear 251. The cross-sectional area of ​​the positive electrode ear 251 is smaller than the minimum cross-sectional area of ​​the negative electrode ear 271.

[0243] The minimum flow cross-sectional area of ​​the positive electrode adapter assembly 25 can be located or provided on the positive electrode adapter 252 of the positive electrode connection assembly 25. In the event of a short circuit, the fuse will be generated at the positive electrode adapter 252. The flow cross-sectional area of ​​the positive electrode adapter 252 is smaller than the minimum flow cross-sectional area of ​​the negative electrode tab 271. The flow cross-sectional area of ​​the positive electrode adapter 252 is smaller than the minimum flow cross-sectional area of ​​the positive electrode tab 251.

[0244] The minimum flow cross-sectional area of ​​the positive electrode adapter assembly 25 is smaller than the minimum flow cross-sectional area of ​​the negative electrode ear 271, which is beneficial for melting at the positive electrode connector when the battery cell 20 is short-circuited, thereby reducing the overall temperature of the battery cell 20 when the short-circuit path is melted, thereby reducing the occurrence of fire, explosion and other problems, so that the battery cell 20 has better reliability.

[0245] In some embodiments, the negative electrode tab 271 is made of copper; and / or the negative electrode adapter 272 is made of copper.

[0246] The negative electrode tab 271 may be made of copper, and the negative electrode adapter 272 may be made of a material other than copper, such as nickel. Alternatively, the negative electrode adapter 272 may be made of copper, and the negative electrode tab 271 may be made of a material other than copper, such as nickel. Alternatively, both the negative electrode tab 271 and the negative electrode adapter 272 may be made of copper to ensure better connection stability between the negative electrode tab 271 and the negative electrode adapter 272.

[0247] The negative electrode ear 271 and / or the negative electrode adapter 272 are made of copper, so that the negative electrode connection assembly 27 has a good current flow capacity, which is conducive to fast charging of the battery cell 20.

[0248] In some embodiments, the flow cross-sectional area of ​​the negative electrode connection assembly 27 is smaller than the flow cross-sectional area of ​​the negative electrode lead-out portion 26 .

[0249] In the embodiment where the negative electrode lead-out portion 26 is disposed on the cover 22, the negative electrode lead-out portion 26 may extend partially into the housing 21, partially extend to the side of the cover 22 facing away from the housing 21, and partially pass through the through-hole in the cover 22. The minimum diameter of the negative electrode lead-out portion 26 is D2, in mm, and the flow cross-section of the negative electrode lead-out portion 26 = π*(D2 / 2)2. For example, as shown in Figures 4 and 5, the negative electrode lead-out portion 26 is riveted to the cover 22 and includes a fourth portion 261, a fifth portion 262, and a sixth portion 263. The fourth portion 261 and the sixth portion 263 are respectively connected to the ends of the fifth portion 262. The fourth portion 261 and the sixth portion 263 are respectively located on opposite sides of the cover 22 in the thickness direction. The fourth portion 261 is located on the side of the cover 22 facing away from the housing 21, and the sixth portion 263 is located on the side of the cover 22 facing the housing 21. The fourth portion 261 is a rectangular structure, the fifth portion 262 is a cylindrical structure, and the sixth portion 263 can be cylindrical or rectangular. The cross-sectional area of ​​the fourth portion 261 is greater than the cross-sectional area of ​​the fifth portion 262, and the cross-sectional area of ​​the sixth portion 263 is greater than the cross-sectional area of ​​the fifth portion 262. The fifth portion 262 is the portion with the smallest cross-sectional area of ​​the negative electrode lead portion 26. The diameter of the fifth portion 262 is equal to the minimum diameter D2 of the positive electrode lead portion 24 (unit: mm). The cross-sectional area of ​​the fifth portion 262 is the current-carrying cross-sectional area of ​​the negative electrode lead portion 26, i.e., the cross-sectional area of ​​the fifth portion 262 = π*(D2 / 2)2.

[0250] As shown in Figures 6 and 7, the negative electrode lead-out portion 26 is connected to the cover 22. The negative electrode lead-out portion 26 includes a fourth portion 261 and a fifth portion 262. The fourth portion 261 is connected to one end of the fifth portion 262. The fourth portion 261 is located on the side of the cover 22 facing away from the housing 21. The fifth portion 262 is inserted into the through hole of the cover 22. Both the fourth portion 261 and the fifth portion 262 are cylindrical in structure. The smallest diameter of the negative electrode lead-out portion 26 is located at the end of the fourth portion 261 facing away from the fifth portion 262.

[0251] The cross-sectional area of ​​the negative electrode connection assembly 27 is smaller than that of the negative electrode lead-out portion 26 , making it difficult for the battery cell 20 to fuse at the negative electrode lead-out portion 26 , which is beneficial for the negative electrode lead-out portion 26 to have a higher current capacity, thereby improving the reliability of the battery cell 20 .

[0252] In some embodiments, the average charging rate of the battery cells 20 is K, that is, the battery cells 6 can achieve KW fast charging. Optionally, K≥2, for example, K is 2, 3, 4, 5 or 6.

[0253] The charge rate is a measure of charging speed, and refers to the current value required to charge the battery 100 to its rated capacity within a specified time.

[0254] For example, taking 4C fast charging as an example, the battery cell 20 can be fast charged and tested as follows:

[0255] (i) The battery cell 20 is allowed to stand for 10 minutes, and then charged to 97% SOC (State of Charge) using an equivalent current of 4C;

[0256] (ii) leaving the battery cell 20 at rest for 30 minutes, and then discharging the battery cell 20 at a constant current of 1C to 3% SOC;

[0257] (iii) repeating steps (i) and (ii) 50 times;

[0258] (iv) charging the battery cell 20 to 97% SOC with an equivalent 4C current;

[0259] (v) Disassemble the battery cell 20, and take the lithium-ion battery cell as an example to observe the lithium deposition on the surface of the negative electrode sheet 232. For example, flatten the negative electrode sheet 232, and measure the total area S1 of the negative electrode active material layer on one side of the negative electrode sheet 232; measure the maximum dimension a of each lithium deposition point on this negative electrode active material layer (there is no lithium deposition around the lithium deposition point) along the length direction of the negative electrode sheet 232, and measure the maximum dimension b of each lithium deposition point along the width direction of the negative electrode sheet 232. Take a / 2 as the median value of the lithium deposition point in the length direction, and take b / 2 as the median value of the lithium deposition point in the width direction. The area of ​​the lithium deposition point is a×b / 4. The sum of the areas of all lithium deposition points is S2. If S2 / S1≤5%, it is considered that the battery cell 6 meets the 4C fast charging requirement.

[0260] K≥2, which can achieve fast charging of 20 battery cells.

[0261] In some embodiments, the positive electrode connection assembly 25 includes a positive electrode ear 251, which includes a plurality of positive electrode ear portions 2511 arranged in a stacked manner; the negative electrode connection assembly 27 includes a negative electrode ear 271, which includes a plurality of negative electrode ear portions 2711 arranged in a stacked manner; the electrode assembly 23 is a wound electrode assembly 23, the number of negative electrode ears 2711 of the electrode assembly 23 is M1, and the number of negative electrode sheets 232 layers of the electrode assembly 23 is M2, satisfying: 1 / 2≤M1 / M2≤1; and / or, the number of positive electrode ears 2511 of the electrode assembly 23 is N1, and the number of positive electrode sheets 231 layers of the electrode assembly 23 is N2, satisfying: 1 / 2≤N1 / N2≤1.

[0262] The electrode assembly 23 includes a straight portion E1 and two bent portions E2, which connect to opposite ends of the straight portion E1. Both the positive tab 251 and the negative tab 271 are located on the straight portion E1. The negative electrode sheet 232 is partially located on the straight portion E2. M2 is the number of negative electrode sheets 232 located on the straight portion E1 and stacked along the thickness direction Z1 of the electrode assembly.

[0263] Part of the positive electrode sheets 231 is located on the straight portion E2 , and N2 is the number of positive electrode sheets 231 located on the straight portion E1 and stacked along the thickness direction Z1 of the electrode assembly.

[0264] The thickness direction Z1 of the electrode assembly, the arrangement direction of the two bends E2, and the extension direction of the winding axis of the electrode assembly 23 are perpendicular to each other. The positive electrode tab 251 and the negative electrode tab 252 are arranged in the straight area E1, and the width direction X1 of the positive electrode tab is parallel to the arrangement direction of the two bends E2.

[0265] A circle of positive electrode sheets 231 of the wound electrode assembly 23 includes two layers of positive electrode sheets 231 stacked Z1 along the thickness direction of the electrode assembly.

[0266] One circle of negative electrode sheet 232 in the wound electrode assembly 23 includes two layers of negative electrode sheet 232 stacked along the thickness direction of the electrode assembly 23. For example, each negative electrode sheet 232 may be provided with one negative electrode ear 2711, i.e., one circle of negative electrode sheet 232 may be provided with two negative electrode ears 2711. Alternatively, one negative electrode ear 2711 may be provided for every ¾ of the circle of the negative electrode sheet 232.

[0267] 1 / 2≤N1 / N2≤1 can be understood as follows: at least two layers of the positive electrode sheet 231 are provided with a positive electrode ear 2511, that is, at least one circle of the positive electrode sheet 231 is provided with a positive electrode ear 2511. At most one layer of the positive electrode sheet 231 is provided with a positive electrode ear 2511, that is, at most one circle of the positive electrode sheet 231 is provided with a positive electrode ear 2511.

[0268] 1 / 2≤M1 / M2≤1 can be understood as follows: at least two layers of negative electrode sheets 271 of the negative electrode sheet 232 are provided with a negative electrode ear 2711, that is, at least one circle of the negative electrode sheet 232 is provided with a negative electrode ear 2711. The last layer of the negative electrode sheet 232 is provided with a negative electrode ear 2711, that is, at most one circle of the negative electrode sheet 232 is provided with a negative electrode ear 2711.

[0269] As shown in FIG19 , each of the two layers of positive electrode sheets 231 is provided with a positive electrode ear 2511 (not shown in FIG19 ), and each layer of negative electrode sheets 232 is provided with a negative electrode ear 2711 (not shown in FIG19 ). All of the positive electrode ears 2511 are stacked along the thickness direction Z1 of the electrode assembly to form a positive electrode ear 251. As can be seen from FIG19 , in the thickness direction Z1 of the electrode assembly, some regions are not provided with a positive electrode ear 2511. The positive electrode ear 251 formed by all of the positive electrode ears 2511 is located on one side of the center plane of the electrode assembly 23. In the thickness direction Z1 of the electrode assembly, all regions are provided with a negative electrode ear 2711. A portion of the negative electrode ear 271 formed by all of the negative electrode ears 2711 is located on one side of the center plane of the electrode assembly 23, and another portion of the negative electrode ear 271 formed by all of the negative electrode ears 2711 is located on the other side of the center plane of the electrode assembly 23. The central plane of the electrode assembly 23 is a plane parallel to the extension direction of the winding axis of the electrode assembly 23 and the arrangement direction of the two bent portions E of the electrode assembly 23 and passing through the winding axis of the electrode assembly 23 .

[0270] As shown in FIG18 , the two layers of positive electrode sheets 231 are provided with a positive electrode ear portion 2511 (not shown in FIG18 ), and the ¾ circle of negative electrode sheet 232 is provided with a negative electrode ear portion 2711 (not shown in FIG18 ). As can be seen from FIG18 , in the thickness direction Z1 of the electrode assembly, some areas are not provided with the positive electrode ear portion 2511. The positive electrode ear 251 formed by all the positive electrode ears 2511 is located on one side of the center plane of the electrode assembly 23. In the thickness direction Z1 of the electrode assembly, some areas are not provided with the negative electrode ear portion 2711.

[0271] 1 / 2≤M1 / M2≤1, and / or, 1 / 2≤N1 / N2≤1, can not only make the positive electrode tab 251 and the negative electrode tab 271 have a higher current capacity, but also help to improve the charging rate of the battery cell 20 to form a fast-charging battery 100.

[0272] Optionally, 1 / 2<M1 / M2≤3 / 4, 1 / 2≤N1 / N2≤3 / 4, so that the positive electrode tab 251 and the negative electrode tab 271 have better current capacity, thereby improving the fast charging capability of the battery cell 20.

[0273] The battery cell 20 may include one electrode assembly 23 or multiple electrode assemblies 23. The positive tabs 251 of the multiple electrode assemblies 23 are electrically connected, and the negative tabs 271 of the multiple electrode assemblies 23 are electrically connected. For example, as shown in FIG3 , in some embodiments, the battery cell 20 includes two electrode assemblies 23.

[0274] The positive tabs 251 of the two electrode assemblies 23 are electrically connected. In embodiments where the positive connection assembly 25 includes the positive tab 251, the positive tabs 251 of the two electrode assemblies 23 are both connected to the positive lead-out portion 24, thereby achieving electrical connection between the positive tabs 251 of the two electrode assemblies 23. In embodiments where the positive connection assembly 25 includes the positive tab 251 and the positive electrode adapter 252, the positive tabs 251 of the two electrode assemblies 23 are both connected to the positive electrode adapter, thereby achieving electrical connection between the positive tabs 251 of the two electrode assemblies 23.

[0275] The negative tabs 271 of the two electrode assemblies 23 are electrically connected. In embodiments where the negative electrode connection assembly 27 includes the negative tab 271, the negative tabs 271 of the two electrode assemblies 23 are both connected to the negative electrode lead-out portion 26, thereby achieving electrical connection between the negative tabs 271 of the two electrode assemblies 23. In embodiments where the negative electrode connection assembly 27 includes the negative tab 271 and the negative electrode adapter 272, the negative tabs 271 of the two electrode assemblies 23 are both connected to the negative electrode connector, thereby achieving electrical connection between the negative tabs 271 of the two electrode assemblies 23.

[0276] The battery cell 20 includes two electrode assemblies 23 , which helps the battery cell 20 have a higher energy density.

[0277] In some embodiments, the negative electrode sheet 232 includes a negative active material layer, and the specific surface area of ​​the negative active material layer particles is 0.5 m 2 / g to 5 m 2 / g.

[0278] The negative electrode active material layer can be made of graphite, hard carbon, soft carbon, silicon oxide, silicon carbon, etc.

[0279] The specific surface area of ​​the negative electrode active material layer particles is the total surface area per unit mass of the negative electrode active material. For example, the specific surface area of ​​the negative electrode active material layer particles can be 0.5 m2 / g, 1 m2 / g, 1.5 m2 / g, 2 m2 / g, 2.5 m2 / g, 3 m2 / g, 3.5 m2 / g, 4 m2 / g, 4.5 m2 / g, 5 m2 / g, etc.

[0280] Unless otherwise specified, the specific surface area in this application is determined by the specific surface area analyzer-static capacity method with reference to the standard GB / T 19587-2017. Specifically, according to the embodiments of this application, a specific surface area and porosity analyzer (instrument model: American Micromeritics TriStar 3020) can be used for measurement according to the manufacturer's instructions.

[0281] The specific surface area of ​​the negative electrode active material layer particles is 0.5m2 / g to 5m2 / g, which can increase the ion embedding sites of the negative electrode active material and increase the rate of ion embedding into the negative electrode active material, thereby improving the charging efficiency of the battery cell 20 and improving the fast charging capability of the battery cell 20.

[0282] In some embodiments, the negative electrode sheet 232 includes a negative electrode active material layer, and the volume distribution particle size DV50 of the negative electrode active material layer is ≤15 μm.

[0283] The volume distribution particle size DV50 of the negative electrode active material layer may be 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 14 μm, 15 μm, or the like.

[0284] Unless otherwise specified, the particle size distribution parameter Dv50 of the negative electrode active material determined by the particle size distribution measurement value in this application is determined by a particle size analyzer-laser diffraction method. Specifically, reference can be made to the standard GB / T 19077-2016, using a Malvern laser particle size analyzer (model: Master Size 3000) and measured according to the manufacturer's instructions.

[0285] The particle size DV50 of the negative electrode active material layer is ≤15 μm, the volume distribution particle size of the negative electrode active material is small, the negative electrode active material has many active reaction sites, and can receive ions faster, thereby improving the charging efficiency of the battery cell 20 and enhancing the fast charging capability of the battery cell 20.

[0286] In some embodiments, the negative electrode sheet 232 includes a negative active material layer, which includes a negative active material, a binder, and a conductive agent.

[0287] The coating weight per unit area of ​​the negative electrode active material layer is less than or equal to 150 mg / 1540.25 mm2.

[0288] For example, a sample of a 1540.25 mm² disc coated only on one side of the negative electrode sheet 232 with the negative electrode active material layer 11b was cut. The sample weight G1 (in mg) was measured. The negative electrode active material layer of the sample was then removed, and the remaining negative electrode current collector was weighed to obtain a weight G2 (in mg). The coating weight per unit area of ​​the negative electrode active material layer can be G1 minus G2.

[0289] The coating weight per unit area of ​​the negative electrode active material layer can be 140 mg / 1540.25 mm2, 130 mg / 1540.25 mm2, 120 mg / 1540.25 mm2, 110 mg / 1540.25 mm2, 1 / 00 ​​mg / 1540.25 mm2, etc.

[0290] The coating weight per unit area of ​​the negative electrode active material layer is less than or equal to 150 mg / 1540.25 mm2. A low coating weight per unit area of ​​the negative electrode active material layer allows for a thinner thickness of the negative electrode active material layer, thereby reducing the resistance to ion insertion into the negative electrode active material layer during charging and improving the charging efficiency of the battery cell 20. A thinner negative electrode sheet 232 can also increase the number of winding layers of the negative electrode sheet 232, thereby allowing for the provision of more negative electrode ears 2711, thereby improving the negative electrode's current carrying capacity and facilitating fast charging of the battery cell 20.

[0291] In some embodiments, the battery cell 20 further includes an electrolyte having an ionic conductivity of 9 mS / cm to 16 mS / cm.

[0292] The electrolyte includes a low-viscosity solvent to reduce the resistance to ion migration and help improve the conductivity of the electrolyte.

[0293] According to the embodiments of the present application, the conductivity of the electrolyte can be detected using a conductivity meter with reference to standard HG / T 4067-2015. Specifically, the resistance of the electrolyte can be tested at a constant temperature of 25±0.1°C and an AC impedance of 1kHz to calculate the conductivity of the electrolyte.

[0294] The ionic conductivity of the electrolyte may be 9 mS / cm, 10 mS / cm, 11 mS / cm, 11.5 mS / cm, 12 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, etc.

[0295] The ionic conductivity of the electrolyte is 9mS / cm to 16mS / cm, which makes the impedance of the battery cell 20 smaller, and makes the ions migrate faster between the positive electrode sheet 231 and the negative electrode sheet 232, and the charging rate of the battery cell 20 is faster, which is conducive to the formation of a fast-charging battery 100.

[0296] In some embodiments, the direct current resistance (DCR) of the battery cell 20 is less than or equal to 0.4 milliohms.

[0297] The impedance of the battery cell 20 refers to the resistance encountered by the current when passing through the battery cell 20. The impedance of the battery cell 20 is measured as follows:

[0298] a) At room temperature, a battery cell 20 with a capacity of Wn is adjusted to 50% SOC with a current of 0.33Cn;

[0299] b) Adjust to 50% SOC and leave for 60 minutes;

[0300] c) The test sample is discharged at a current of 4Cn for 30s and then the voltage V0 of the battery cell before discharge and the voltage V1 of the battery cell after discharge are obtained;

[0301] d) Calculation yields: DCR = (V0 - V1) / 4Cn.

[0302] The DC impedance of the battery cell 20 may be 0.1 milliohm, 0.15 milliohm, 0.2 milliohm, 0.25 milliohm, 0.3 milliohm, 0.35 milliohm, 0.4 milliohm, etc.

[0303] The DC impedance of the battery cell 20 is less than or equal to 0.4 milliohms. The battery cell 20 has a smaller DC impedance, thereby increasing the migration rate of ions, thereby improving the charging efficiency of the battery cell 20 and improving the fast charging capability of the battery cell 20.

[0304] An embodiment of the present application further provides a battery 100 , which includes the battery cell 20 provided in any of the above embodiments.

[0305] The battery cell 20 provided in any of the above embodiments has good reliability, and the battery 100 including the battery cell 20 also has good reliability.

[0306] As shown in Figure 21, in some embodiments, the battery 100 also includes a plurality of thermal management components 30 arranged along a first direction X2, the thermal management components 30 are used to adjust the temperature of the battery cells 20, and a plurality of battery cells 20 arranged along a second direction Y2 are arranged between two adjacent thermal management components, and the first direction X2 is perpendicular to the second direction Y2.

[0307] The thermal management component 30 can lower the temperature of the battery cell 20 or increase the temperature of the battery cell 20. The thermal management component 30 can be a plate-like structure with a flow channel formed inside to accommodate a heat exchange medium. The heat exchange medium in the flow channel can be water, air, a mixture of water and ethylene glycol, a refrigerant, a phase change material, etc., and the heat exchange medium can be circulating. In other embodiments, the heat exchange medium can also be a solid, such as paraffin, etc. The heat exchange function can be achieved by the physical change of the heat exchange medium. For example, when paraffin changes from a solid state to a liquid, it can absorb heat to achieve the effect of cooling the battery cell 20. The thermal management component 30 can also be called a water-cooled plate, a liquid-cooled plate, a heat exchange plate, a temperature regulating plate, etc.

[0308] The arrangement direction of the thermal management component 30 is perpendicular to the arrangement direction of the battery cells 20 , so one thermal management component 30 can simultaneously perform heat exchange with multiple battery cells 20 , thereby improving temperature regulation efficiency.

[0309] In some embodiments, the thermal management component 30 is adhesively connected to the outer surface of the battery cell 20 .

[0310] For example, the thermal management component 30 and the outer surfaces of the battery cells 20 can be bonded together by applying glue to the surface of the thermal management component 30 facing the battery cells 20 and the surface of the battery cells 20 facing the thermal management component 30. The glue provided between the thermal management component 30 and the battery cells 20 can be thermally conductive glue to improve the thermal conductivity between the thermal management component 30 and the battery cells 20.

[0311] The thermal management component 30 and the outer surface of the battery cell 20 are bonded and connected so that the thermal management component 30 and the battery cell 20 have a stable relative position relationship, which is beneficial to improving heat exchange efficiency.

[0312] An embodiment of the present application provides an electrical device, which includes a battery cell 20 provided in any of the above embodiments.

[0313] The battery cell 20 provided in any of the above embodiments has good reliability, which is beneficial to improving the reliability of power supply through the battery cell 20 .

[0314] The present embodiment provides a battery cell 20, which includes an electrode assembly 23, a positive electrode lead 24, a positive electrode connector 25, a negative electrode lead 26, and a negative electrode connector 27. The electrode assembly 23 includes a positive electrode sheet 231 and a negative electrode sheet 232. The positive electrode connector 25 electrically connects the positive electrode sheet 231 and the positive electrode lead 24, which is used to electrically connect to components external to the battery cell 20. The negative electrode connector 27 electrically connects the negative electrode sheet 232 and the negative electrode lead 26, which is used to electrically connect to components external to the battery cell 20. The positive electrode connector 25 is a positive electrode tab 251, which is welded to the positive electrode lead 24. A fuse zone is formed in the positive electrode tab 251. The negative electrode connector 27 is a negative electrode tab 271, which is welded to the negative electrode lead 26. The cross-sectional area of ​​the fuse zone is smaller than the cross-sectional area of ​​the positive electrode lead portion 24, which is smaller than the cross-sectional area of ​​the negative electrode tab 271, which is smaller than the cross-sectional area of ​​the negative electrode tab 271. The cross-sectional area of ​​the negative electrode tab 271 is smaller than the cross-sectional area of ​​the negative electrode lead portion 26. The cross-sectional area of ​​the fuse zone is A1 (mm²), the minimum cross-sectional area of ​​the negative electrode connector assembly 27 is A2 (mm²), the melting point of the positive electrode connector assembly 25 is B1 (°C), the melting point of the negative electrode connector assembly 27 is B2 (°C), the resistivity of the positive electrode connector assembly 25 is C1 (Ωm), and the resistivity of the negative electrode connector assembly 27 is C2 (Ωm), satisfying the following: A1 < A2 * (B2 / B1) * (C1 / C2).

[0315] The present embodiment further provides a battery cell 20, which includes an electrode assembly 23, a positive electrode lead 24, a positive electrode connector 25, a negative electrode lead 26, and a negative electrode connector 27. The electrode assembly 23 includes a positive electrode sheet 231 and a negative electrode sheet 232. The positive electrode connector 25 electrically connects the positive electrode sheet 231 and the positive electrode lead 24, which is used to electrically connect to components external to the battery cell 20. The negative electrode connector 27 electrically connects the negative electrode sheet 232 and the negative electrode lead 26, which is used to electrically connect to components external to the battery cell 20. The positive electrode connector 25 includes a positive tab 251 and a positive adapter 252, which connects the positive tab 251 to the positive electrode lead 24 via the positive adapter 252. A fuse zone is formed in the positive adapter 252. The negative electrode connection assembly 27 includes a negative electrode tab 271 and a negative electrode adapter 272. The cover electrode tab is connected to the negative electrode lead 26 via the negative electrode adapter 272. The cross-sectional area of ​​the fuse zone is smaller than that of the positive electrode tab 251, which in turn is smaller than that of the positive electrode lead 24. The cross-sectional area of ​​the positive electrode lead 24 is smaller than that of the negative electrode tab 271. The cross-sectional area of ​​the negative electrode tab 271 is smaller than that of the negative electrode adapter 272, which in turn is smaller than that of the negative electrode lead 26. The overflow cross-sectional area of ​​the fuse zone is A1, measured in mm2. The minimum overflow cross-sectional area of ​​the negative electrode connection assembly 27 is A2, measured in mm2. The melting point of the positive electrode connection assembly 25 is B1, measured in °C. The melting point of the negative electrode connection assembly 27 is B2, measured in °C. The resistivity of the positive electrode connection assembly 25 is C1, measured in Ωm. The resistivity of the negative electrode connection assembly 27 is C2, measured in Ωm. The following conditions are satisfied: A1 < A2 * (B2 / B1) * (C1 / C2).

[0316] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, comprising: An electrode assembly, including a positive electrode sheet and a negative electrode sheet; A positive electrode lead-out portion and a positive electrode connection assembly, wherein the positive electrode connection assembly electrically connects the positive electrode sheet and the positive electrode lead-out portion, and the positive electrode lead-out portion is used to electrically connect to components outside the battery cell; A negative electrode lead-out portion and a negative electrode connection assembly, wherein the negative electrode connection assembly electrically connects the negative electrode sheet and the negative electrode lead-out portion, and the negative electrode lead-out portion is used to electrically connect to components outside the battery cell; The minimum cross-sectional area of ​​the positive electrode connection assembly is smaller than the cross-sectional area of ​​the positive electrode lead-out portion, the melting point of the positive electrode connection assembly is smaller than the melting point of the negative electrode connection assembly, and the minimum cross-sectional area of ​​the positive electrode connection assembly is A1, in mm. 2 The minimum cross-sectional area of ​​the negative electrode connection assembly is A2, in mm 2 , the melting point of the positive electrode connection component is B1, the unit is ℃, the melting point of the negative electrode connection component is B2, the unit is ℃, the resistivity of the positive electrode connection component is C1, the unit is Ωm, the resistivity of the negative electrode connection component is C2, the unit is Ωm, satisfying: A1<A2*(B2 / B1)*(C1 / C2).

2. The battery cell according to claim 1, wherein: A1≤2.5A2.

3. The battery cell according to claim 2, wherein: A1≤2.3A2.

4. The battery cell according to claim 3, wherein: A1≤1.5A2.

5. The battery cell according to claim 4, wherein: A1<A2.

6. The battery cell according to any one of claims 1 to 5, wherein: The positive electrode ear comprises a plurality of positive electrode ear portions arranged in a stacked manner, the negative electrode connection assembly comprises a negative electrode ear, the negative electrode ear is connected to the negative electrode sheet, and the negative electrode ear comprises a plurality of negative electrode ear portions arranged in a stacked manner; The number of the positive electrode ears is smaller than the number of the negative electrode ears.

7. The battery cell according to any one of claims 1 to 6, wherein: The negative electrode connection assembly includes a negative electrode ear, the negative electrode ear is connected to the negative electrode sheet, and the width of the positive electrode ear is smaller than the width of the negative electrode ear.

8. The battery cell according to any one of claims 1 to 7, wherein: The positive electrode connection assembly includes a positive electrode ear, which is connected to the positive electrode sheet, and the minimum flow cross-sectional area of ​​the positive electrode ear is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion.

9. The battery cell according to claim 8, wherein: The rated capacity of the battery cell is W, in Ah, and satisfies A1 / W≥0.

15.

10. The battery cell according to claim 8 or 9, wherein: The positive electrode tab is connected to the positive electrode lead-out portion.

11. The battery cell according to claim 8 or 9, wherein: The positive electrode connection assembly further includes a positive electrode adapter, the positive electrode adapter connects the positive electrode ear and the positive electrode lead-out portion, the positive electrode adapter includes a first welding area, a second welding area and a transition connection portion, the first welding area is connected to the positive electrode ear, the second welding area is connected to the positive electrode lead-out portion, and the transition connection portion is connected between the first welding area and the second welding area; The cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the first welding zone, and / or The cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the second welding zone.

12. The battery cell according to any one of claims 1 to 7, wherein: The positive electrode connection assembly also includes a positive electrode adapter and a positive electrode ear, the positive electrode ear is connected to the positive electrode sheet, the positive electrode adapter connects the positive electrode ear and the positive electrode lead-out portion, the minimum flow cross-sectional area of ​​the positive electrode adapter is smaller than the flow cross-sectional area of ​​the positive electrode lead-out portion, and the minimum flow cross-sectional area of ​​the positive electrode adapter is smaller than the flow cross-sectional area of ​​the positive electrode ear.

13. The battery cell according to claim 12, wherein: The positive electrode adapter comprises a first welding area, a second welding area and a transition connection portion, the first welding area is connected to the positive electrode ear, the second welding area is connected to the positive electrode lead-out portion, and the transition connection portion is connected between the first welding area and the second welding area; The cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the first welding zone, and / or The cross-sectional area of ​​the transition connection portion is greater than or equal to the minimum cross-sectional area of ​​the second welding zone.

14. The battery cell according to claim 12 or 13, wherein: The rated capacity of the battery cell is W, in Ah, and satisfies A1 / W≥0.

2.

15. The battery cell according to any one of claims 12 to 14, wherein: The thickness of at least a portion of the positive electrode adapter is H1, which satisfies 1.0 mm ≤ H1 ≤ 1.5 mm.

16. The battery cell according to claim 14 or 15, wherein: The positive electrode adapter includes a first connecting portion and a second connecting portion, the first connecting portion is connected to the positive electrode ear, the second connecting portion is connected to the positive electrode lead-out portion, the thickness of the first connecting portion is greater than or equal to the thickness of the second connecting portion, the thickness of the first connecting portion is H1, and satisfies 1.0mm≤H1≤1.5mm.

17. The battery cell according to any one of claims 12 to 16, wherein: The material of the positive electrode ear is aluminum; and / or the material of the positive electrode adapter is aluminum.

18. The battery cell according to any one of claims 1 to 17, wherein: The negative electrode connection assembly further includes a negative electrode adapter and a negative electrode ear, wherein the negative electrode ear is connected to the negative electrode sheet, and the negative electrode adapter connects the negative electrode ear and the negative electrode lead-out portion.

19. The battery cell according to claim 18, wherein: The minimum flow cross-sectional area of ​​the negative electrode adapter is greater than the maximum flow cross-sectional area of ​​the negative electrode lug; or the minimum flow cross-sectional area of ​​the negative electrode lug is greater than the maximum flow cross-sectional area of ​​the negative electrode adapter.

20. The battery cell according to claim 18 or 19, wherein: The thickness of at least a portion of the negative electrode adapter is H2, which satisfies 0.6 mm ≤ H2 ≤ 1.0 mm.

21. The battery cell according to claim 20, wherein: The negative electrode adapter includes a third connecting portion and a fourth connecting portion, the third connecting portion is connected to the negative electrode ear, the fourth connecting portion is connected to the negative electrode lead-out portion, the thickness of the third connecting portion is greater than or equal to the thickness of the fourth connecting portion, the thickness of the third connecting portion is H2, and satisfies 0.6mm≤H2≤1.0mm.

22. The battery cell according to any one of claims 18 to 21, wherein: The minimum flow cross-sectional area of ​​the positive electrode connection assembly is smaller than the minimum flow cross-sectional area of ​​the negative electrode ear.

23. The battery cell according to claim 18, wherein: The negative electrode ear is made of copper; and / or the negative electrode adapter is made of copper.

24. The battery cell according to any one of claims 1 to 23, wherein: The flow cross-sectional area of ​​the negative electrode connection assembly is smaller than the flow cross-sectional area of ​​the negative electrode lead-out portion.

25. The battery cell according to any one of claims 1 to 24, wherein: The average charging rate of the battery cell is K, satisfying K≥2.

26. The battery cell according to any one of claims 1 to 25, wherein: The positive electrode connection assembly includes a positive electrode ear, and the positive electrode ear includes a plurality of positive electrode ear portions arranged in a stacked manner; the negative electrode connection assembly includes a negative electrode ear, and the negative electrode ear includes a plurality of negative electrode ear portions arranged in a stacked manner; The electrode assembly is a wound electrode assembly, the number of negative electrode ears of the electrode assembly is M1, the number of layers of the negative electrode sheet along the stacking direction of the plurality of electrode ears is M2, and the following conditions are satisfied: 1 / 2≤M1 / M2≤1; and / or the number of positive electrode ears of the electrode assembly is N1, the number of layers of the positive electrode sheet along the stacking direction of the plurality of positive electrode ears is N2, and the following conditions are satisfied: 1 / 2≤N1 / N2≤1; Optionally, 1 / 2<M1 / M2≤3 / 4, 1 / 2≤N1 / N2≤3 / 4.

27. The battery cell according to any one of claims 1 to 26, wherein: The negative electrode sheet includes a negative electrode active material layer, and the specific surface area of ​​the particles of the negative electrode active material layer is 0.5 m 2 / g~5m 2 / g.

28. The battery cell according to any one of claims 1 to 27, wherein: The negative electrode sheet comprises a negative electrode active material layer, and the volume distribution particle size D of the negative electrode active material layer V 50≤15μm.

29. The battery cell according to any one of claims 1 to 28, wherein: The negative electrode sheet comprises a negative electrode active material layer, and the coating weight per unit area of ​​the negative electrode active material layer is less than or equal to 150 mg / 1540.25 mm 2 .

30. The battery cell according to any one of claims 1 to 29, wherein: The battery cell further includes an electrolyte, and the ion conductivity of the electrolyte is 9 mS / cm to 16 mS / cm.

31. The battery cell according to any one of claims 1 to 30, wherein: The DC impedance of the battery cell is less than or equal to 0.4 milliohms.

32. A battery comprising the battery cell according to any one of claims 1 to 31.

33. The battery according to claim 32, wherein The battery further includes a plurality of thermal management components arranged along a first direction, the thermal management components being used to adjust the temperature of the battery cells, a plurality of battery cells arranged along a second direction being arranged between two adjacent thermal management components, and the first direction being perpendicular to the second direction.

34. The battery according to claim 33, wherein The thermal management component is adhesively connected to the outer surface of the battery cell.

35. An electrical device comprising a battery cell according to any one of claims 1 to 34.

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