Battery and electric device

Abstract

A battery (2) and an electric device. The battery (2) comprises a battery cell (6) and a plurality of heat exchange plates (7). The battery cell (6) comprises a housing (20) and an electrode unit (30) accommodated in the housing (20), wherein the electrode unit (30) comprises a plurality of first electrode plate layers (111), the plurality of first electrode plate layers (111) having the same polarity and being stacked in a first direction, some of the first electrode plate layers (111) are provided with first tabs (111a) which form two first tab groups (111b), each first tab group (111b) comprises a plurality of first tabs (111a) stacked and connected to one another, and the first electrode plate layer (111) which is provided with no first tab (111a) is provided between the two first tab groups (111b). The plurality of heat exchange plates (7) are arranged in the first direction, the housing (20) is arranged between adjacent heat exchange plates (7) and can exchange heat with the heat exchange plate (7), and each first electrode plate layer (111) at least partially overlaps the heat exchange plate (7) in the first direction.

Description

Batteries and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202322655888.X, filed on September 28, 2023, entitled “Battery and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

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

[0004] With the development of new energy technology, batteries are used more and more widely, for example, in mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and power tools.

[0005] The development of battery technology must take into account multiple design factors at the same time. How to improve the cycle life of batteries is an important research direction in the battery field.

[0006] Summary of the Invention

[0007] The present application provides a battery and an electrical device, which can improve the cycle life of the battery.

[0008] In a first aspect, the present application provides a battery comprising a battery cell and a plurality of heat exchange plates. The battery cell comprises a housing and an electrode unit housed within the housing. The electrode unit comprises a plurality of first electrode sheet layers, each of which has the same polarity and is stacked along a first direction. A portion of the first electrode sheet layers is provided with first tabs, forming two first tab groups. Each first tab group comprises a plurality of stacked and connected first tabs, with a first electrode sheet layer without first tabs disposed between the two first tab groups. A plurality of heat exchange plates are disposed along a first direction. The housing is disposed between adjacent heat exchange plates and is capable of exchanging heat with the heat exchange plates. In the first direction, each first electrode sheet layer at least partially overlaps the heat exchange plate.

[0009] The heat exchange plates on both sides of the outer shell are respectively arranged close to the two first pole lug groups. During the charge and discharge process of the battery, the heat exchange plates can absorb the heat generated by the two first pole lug groups through the outer shell, thereby reducing the temperature rise of each first pole lug and reducing the temperature difference of multiple first electrode layers. The first pole piece layer between the two first pole lug groups is not provided with a first pole lug. Therefore, even if the first pole piece layer between the two first pole lug groups is far away from the heat exchange plates, the temperature rise of the first pole piece layer between the two first pole lug groups is also small, thereby reducing the temperature difference of multiple first pole piece layers. The embodiment of the present application reduces the temperature difference and impedance difference of different first pole piece layers by simultaneously arranging heat exchange plates on both sides of the outer shell and removing part of the first pole lugs in the middle of the electrode unit, thereby improving the current consistency, improving the charge and discharge performance of the battery cell, and extending the cycle life of the battery cell.

[0010] In some embodiments, the total number of first electrode sheet layers is N, the number of first electrode tabs in each first electrode tab group is K1, and K1 and N satisfy: 1 / 4≤K1 / N≤7 / 16.

[0011] Limiting K1 / N to greater than or equal to 1 / 4 can increase the total number of first electrode tabs, improve the current capacity of the electrode assembly, reduce the current and temperature rise of each first electrode tab, and improve the fast charging capability of the battery cell. In this embodiment of the application, limiting K1 / N to less than or equal to 7 / 16 can reduce the number of first electrode tabs away from the heat exchange plate in the first direction, thereby reducing the temperature and impedance differences among multiple first electrode layer layers and improving current consistency.

[0012] In some embodiments, 5 / 16≤K1 / N≤7 / 16, thereby further balancing the current capacity of the electrode assembly and the temperature difference between the first electrode layer, improving the current consistency of the electrode assembly, enhancing the fast charging capability of the battery cell, and extending the cycle life of the battery cell.

[0013] In some embodiments, the number of first pole sheet layers located between two first pole tab groups and without first pole tabs is K2, and K2 and N satisfy: 1 / 8≤K2 / N≤1 / 2.

[0014] Limiting K2 / N to less than or equal to 1 / 2 allows for more first electrode sheet layers with first tabs to be reserved for the electrode unit, increasing the total number of first tabs, improving the electrode assembly's current capacity, reducing the current and temperature rise of each first tab, and enhancing the fast-charging capability of the battery cell. In this embodiment of the present application, limiting K2 / N to greater than or equal to 1 / 8 can reduce the number of first tabs farther away from the heat exchange plate in the first direction, thereby reducing temperature and impedance differences across multiple first electrode sheet layers and improving current consistency.

[0015] In some embodiments, 1 / 8≤K2 / N≤3 / 8, thereby further balancing the current capacity of the electrode assembly and the temperature difference between the first electrode layer, improving the current consistency of the electrode assembly, enhancing the fast charging capability of the battery cell, and extending the cycle life of the battery cell.

[0016] In some embodiments, the housing includes two first shell walls disposed opposite each other along a first direction, each first shell wall being configured to exchange heat with the heat exchange plate. In the first direction, the minimum spacing between the outer surface of a first shell wall and the first tab closest to the first shell wall is D1 mm. K1, N, and D1 satisfy the following: 21 ≤ 88 × K1 / N - D1 / 5 ≤ 38.4.

[0017] 88×K1 / N-D1 / 5 is limited to greater than or equal to 21 to increase the number of first pole tabs or shorten the heat conduction path between the first pole tab and the heat exchange plate, thereby reducing heat generation in the first pole tab, lowering the temperature rise of the first pole tab, and improving the charge and discharge performance of the battery cell. In the embodiment of the present application, 88×K1 / N-D1 / 5 is limited to less than or equal to 38.4 to reduce the difference in heat conduction path between the innermost first pole tab of the first pole tab group and the heat exchange plate and the outermost first pole tab of the first pole tab group and the heat exchange plate, thereby reducing the maximum temperature difference between multiple first pole sheet layers, improving the current consistency of the electrode assembly, improving the fast charging capability of the battery cell, and extending the cycle life of the battery cell.

[0018] In some embodiments, 26.9≤88×K1 / N-D1 / 5≤38.3.

[0019] In some embodiments, the housing includes two first shell walls disposed opposite each other along a first direction, each first shell wall being configured to exchange heat with the heat exchange plate. In the first direction, a minimum spacing D1 mm is defined between an outer surface of a first shell wall and a first tab closest to the first shell wall. D1 ranges from 0.5 to 5 mm.

[0020] D1 is limited to greater than or equal to 0.5 to ensure that the thickness and strength of the first shell wall meet the requirements and improve the reliability of the battery cell. In the embodiment of the present application, D1 is limited to less than or equal to 5 to shorten the heat conduction path between the first tab and the heat exchange plate, reduce the heat generated by the first tab, reduce the temperature rise of the first tab, and improve the charge and discharge performance of the battery cell.

[0021] In some embodiments, D1 is 1-3.

[0022] In some embodiments, the two first tab groups are spaced apart along the first direction. The ends of the two first tab groups are bent in a direction toward each other and the ends of the two first tab groups are opposite to each other along the first direction. By bending the two first tab groups, space can be saved and space utilization can be improved.

[0023] In some embodiments, the middlemost first pole piece layer among the multiple first pole piece layers is not provided with a first pole tab, and the first pole piece layers corresponding to the two first pole tab groups are respectively located on both sides of the middlemost first pole piece layer.

[0024] Among all the first electrode sheet layers, the middle-most first electrode sheet layer is farthest from the heat exchange plate. In the embodiments of the present application, the middle-most first electrode sheet layer is not provided with a first electrode tab. This can reduce the temperature rise of the middle-most first electrode sheet layer, reduce the temperature difference between the middle-most first electrode sheet layer and the other first electrode sheet layers, and improve current consistency. Arranging the first electrode sheet layers corresponding to the two first electrode tab groups on either side of the middle-most first electrode sheet layer can shorten the heat conduction path between each first electrode tab group and the corresponding heat exchange plate, thereby reducing the temperature rise of each first electrode tab and reducing the temperature difference between the two first electrode tab groups, thereby improving the charge and discharge capacity of the battery cell.

[0025] In some embodiments, the electrode unit includes at least one electrode assembly, each electrode assembly including a first electrode piece and a second electrode piece with opposite polarities. The first electrode piece includes at least a portion of a plurality of first electrode piece layers, and the plurality of first electrode piece layers of the first electrode piece form at least one first electrode tab group.

[0026] The first pole piece is a continuously arranged whole. Therefore, the first pole piece layer without the first pole tab can conduct current through the pole piece layer provided on the first pole tab.

[0027] In some embodiments, the first electrode sheet and the second electrode sheet are wound. In other embodiments, the electrode assembly includes a plurality of second electrode sheets, the first electrode sheet layers and the second electrode sheets of the first electrode sheet are alternately arranged along a first direction, and the first electrode sheet includes a bending layer that connects two adjacent first electrode sheet layers.

[0028] In some embodiments, the electrode unit includes two electrode assemblies arranged along a first direction, and each electrode assembly includes a first electrode tab group.

[0029] Setting up two electrode assemblies can reduce the number of first electrode sheet layers of a single electrode assembly and reduce the risk of misalignment of the first electrode tab during the molding process of the electrode assembly.

[0030] In some embodiments, the first electrode piece is a negative electrode piece. During fast charging of a battery cell, the first electrode tab generates significant heat. By providing a heat exchange plate and two first electrode tab groups, the embodiments of the present application can reduce the temperature rise of the first electrode tab during fast charging, improve the temperature consistency of the electrode assembly, and enhance the fast charging performance of the battery cell.

[0031] In some embodiments, the first electrode sheet includes a negative electrode active material, and the volume distribution particle size Dv50 of the negative electrode active material is ≤15 μm.

[0032] The volume distribution particle size of the negative electrode active material is smaller, and the negative electrode active material has more active reaction sites, which can receive ions faster, thereby improving the charging efficiency of the battery cell and enhancing the fast charging capability of the battery cell.

[0033] In some embodiments, the first electrode sheet includes a negative electrode active material, and the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, silicon oxide, or silicon carbon.

[0034] In some embodiments, the specific surface area of ​​the negative electrode active material is 0.5 m 2 / g-5m 2 The embodiments of the present application 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.

[0035] In some embodiments, the first electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector; 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 .

[0036] The negative electrode active material layer has a small coating weight per unit area, and the negative electrode active material layer can have a smaller thickness, thereby reducing the resistance of ions embedded in the negative electrode active material layer during charging and improving the charging efficiency of the battery cell.

[0037] In some embodiments, the electrode unit includes multiple second electrode sheet layers, each having a polarity opposite to that of the first electrode sheet layer, and the second electrode sheet layers and the first electrode sheet layers are stacked along a first direction. A portion of the second electrode sheet layers are provided with second electrode tabs to form two second electrode tab groups, each second electrode tab group including multiple second electrode tabs stacked and connected, with a second electrode sheet layer without second electrode tabs disposed between the two second electrode tab groups.

[0038] The heat exchange plates on both sides of the outer shell are respectively arranged close to the two second pole lug groups. During the charge and discharge process of the battery, the heat exchange plates can absorb the heat generated by the two second pole lug groups through the outer shell, thereby reducing the temperature rise of each second pole lug and reducing the temperature difference of multiple second pole sheet layers. The second pole sheet layer between the two second pole lug groups is not provided with a second pole lug. Therefore, even if the second pole sheet layer between the two second pole lug groups is far away from the heat exchange plates, the temperature rise of the second pole sheet layer between the two second pole lug groups is also small, thereby reducing the temperature difference of multiple second pole sheet layers. The embodiment of the present application reduces the temperature difference and impedance difference of different second pole sheet layers by simultaneously arranging heat exchange plates on both sides of the outer shell and removing part of the second pole lugs in the middle of the electrode unit, thereby improving the current consistency, improving the charge and discharge performance of the battery cell, and extending the cycle life of the battery cell.

[0039] In some embodiments, the total number of second electrode sheet layers is M, the number of second electrode tabs in each second electrode tab group is K3, and K3 and M satisfy: 1 / 4≤K3 / M≤7 / 16. Optionally, 5 / 16≤K3 / M≤7 / 16.

[0040] Limiting K3 / M to greater than or equal to 1 / 4 can increase the total number of second electrode tabs, improve the current capacity of the electrode assembly, reduce the current and temperature rise of each second electrode tab, and improve the fast charging capability of the battery cell. In this embodiment of the application, limiting K3 / M to less than or equal to 7 / 16 can reduce the number of second electrode tabs farther away from the heat exchange plate in the first direction, thereby reducing the temperature and impedance differences among multiple second electrode layer layers and improving current consistency.

[0041] In some embodiments, the number of second electrode sheet layers located between two second electrode tab groups and without second electrode tabs is K4, and K4 and M satisfy: 1 / 8≤K4 / M≤1 / 2. Optionally, 1 / 8≤K4 / M≤3 / 8.

[0042] Limiting K4 / M to less than or equal to 1 / 2 allows for more second-electrode tabs to be reserved for the electrode unit, increasing the total number of second-electrode tabs, improving the electrode assembly's current capacity, reducing the current and temperature rise of each second-electrode tab, and enhancing the fast-charging capability of the battery cell. In this embodiment, limiting K4 / M to greater than or equal to 1 / 8 reduces the number of second-electrode tabs farther from the heat exchange plate in the first direction, thereby reducing temperature and impedance differences across multiple second-electrode tab layers and improving current consistency.

[0043] In some embodiments, the first electrode tab is a negative electrode tab, and the second electrode tab is a positive electrode tab. The number of first electrode tabs in the first electrode tab group is greater than the number of second electrode tabs in the second electrode tab group.

[0044] The number of the first pole ears is different from the number of the second pole ears, so that the overcurrent capacity of the positive electrode and the overcurrent capacity of the negative electrode can be differentiated as needed to meet design requirements.

[0045] In some embodiments, the first tab is a copper tab, the second tab is an aluminum tab, and the sum of the cross-sectional areas of all the second tabs is A1, in mm. 2 The sum of the cross-sectional areas of all first tabs is A2, in mm 2 A1≤2.5A2; optional, A1≤1.5A2.

[0046] Taking into account the melting point, resistivity and flow area of ​​the copper and aluminum tabs, A1 / A2 is limited to less than or equal to 2.5. When the current is too large (for example, in a short circuit), the aluminum tab can be melted before the copper tab, thereby cutting off the circuit in time and reducing safety risks.

[0047] In some embodiments, the battery cell further includes an electrolyte contained within the housing, wherein the electrolyte has an ionic conductivity of 9 mS / cm to 16 mS / cm. The electrolyte's good ionic conductivity can reduce the impedance of the battery cell and increase the ion migration rate, thereby improving the charging efficiency and fast-charging capability of the battery cell.

[0048] In some embodiments, the DC impedance of the battery cell is less than or equal to 0.4 milliohms. The battery cell has a smaller DC impedance, thereby increasing the migration rate of ions, thereby improving the charging efficiency of the battery cell and improving the fast charging capability of the battery cell.

[0049] In some embodiments, each first electrode layer includes a electrode body, and a portion of the first electrode layers is provided with a first electrode tab extending from an end of the electrode body along a second direction, the second direction being perpendicular to the first direction. In the first direction, each electrode body at least partially overlaps the heat exchange plate.

[0050] In some embodiments, the size of the heat exchange plate is H1, the size of the pole piece body is H2, 0.6≤H1 / H2≤1.2; optionally, 0.8≤H1 / H2≤1.1.

[0051] Setting H1 / H2 to greater than or equal to 0.6 increases the heat exchange area between the heat exchange plate and the electrode body, improving heat exchange efficiency, reducing temperature changes of the electrode body during charging and discharging, and improving the charge and discharge capacity of the battery cell. In this embodiment of the application, setting H1 / H2 to less than or equal to 1.2 reduces waste in the heat exchange capacity of the heat exchange plate, reduces the weight and volume of the heat exchange plate, and improves the energy density of the battery.

[0052] In some embodiments, in the second direction, a distance between an edge of the pole piece body close to the first pole tab and an edge of the heat exchange plate close to the first pole tab is L1, where L1≤20mm; optionally, L1≤15mm.

[0053] In the case where the edge of the pole piece body near the first tab extends beyond the edge of the heat exchange plate near the first tab, the embodiment of the present application limits L1 to less than or equal to 20mm. This allows the heat exchange plate to be as close as possible to the connection between the first tab and the pole piece body, that is, to quickly move the heat exchange plate to a location with a greater temperature rise, thereby reducing the temperature rise of the electrode assembly and improving the cycling performance of the battery cell. In the case where the edge of the heat exchange plate near the first tab extends beyond the edge of the pole piece body near the first tab, the embodiment of the present application limits L1 to less than or equal to 20mm. This can reduce excessive design of the heat exchange plate, reduce the space and weight of the heat exchange plate, and improve energy density.

[0054] In some embodiments, in the second direction, the edge of the heat exchange plate close to the first pole lug extends beyond the edge of the pole piece body close to the first pole lug; or, in the second direction, the edge of the heat exchange plate close to the first pole lug is flush with the edge of the pole piece body close to the first pole lug.

[0055] The heat exchange plate can cover the connection between the main body and the first pole tab, thereby shortening the heat transfer path between the first pole tab and the heat exchange plate, reducing the temperature rise at the connection between the main body and the first pole tab, and improving the cycle performance of the battery cell.

[0056] In some embodiments, the housing includes two first shell walls opposing each other along a first direction, two second shell walls opposing each other along a second direction, and two third shell walls opposing each other along a third direction, wherein the first direction, the second direction, and the third direction are perpendicular to each other. The area of ​​the first shell wall is greater than the area of ​​the second shell wall, and the area of ​​the first shell wall is greater than the area of ​​the third shell wall.

[0057] The first shell wall is a shell wall with a larger outer shell area. By using the first shell wall to exchange heat with the heat exchange plate, the heat exchange area can be increased, the heat exchange efficiency can be improved, the temperature difference between different areas of the electrode assembly can be reduced, and the charge and discharge performance of the battery cell can be improved.

[0058] In some embodiments, a plurality of battery cells are arranged sequentially between adjacent heat exchange plates, and the arrangement direction of the plurality of battery cells is perpendicular to the first direction. The heat exchange plates can exchange heat with multiple battery cells simultaneously, thereby improving heat exchange efficiency and simplifying the battery structure.

[0059] In a second aspect, the present application provides an electrical device, which includes a battery provided by any embodiment of the first aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0061] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0062] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application;

[0063] FIG3 is a schematic cross-sectional view of a battery provided in some embodiments of the present application;

[0064] FIG4 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0065] FIG5 is an enlarged schematic diagram of the frame in FIG3 ;

[0066] FIG6 is an enlarged schematic diagram of the frame in FIG5 ;

[0067] FIG7 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application;

[0068] FIG8 is a schematic cross-sectional view taken along the EE direction of FIG7 ;

[0069] FIG9 is a partial cross-sectional schematic diagram of batteries provided in some other embodiments of the present application;

[0070] FIG10 is a schematic diagram of an electrode assembly of a battery cell provided in some other embodiments of the present application;

[0071] FIG11 is a schematic diagram of an electrode assembly of a battery cell provided in some other embodiments of the present application;

[0072] 12 to 14 are schematic diagrams of battery cells according to some embodiments of the present application at different angles, showing multiple detection sites.

[0073] The accompanying drawings are numbered as follows: 1. vehicle; 2. battery; 3. controller; 4. motor; 5. housing; 5a. first housing portion; 5b. second housing portion; 5c. accommodation space; 6. battery cell; 7. heat exchange plate; 10. electrode assembly; 11. first pole piece; 111. first pole piece layer; 111a. first pole tab; 111b. first pole tab group; 111c. pole piece body; 112. bending layer; 11a. negative electrode current collector; 11b. negative electrode active material layer; 12. second pole piece; 121. second pole piece layer; 121a. second pole tab; 121b. second pole tab group; 13. separator; 10a. straight region; 10b. bending region; 20. Outer shell; 21. Shell; 211. First shell wall; 211a. Outer surface; 212. Second shell wall; 213. Third shell wall; 214. Bottom wall; 22. End cap; 30. Electrode unit; 40. Electrode terminal; Y, first direction; Z, second direction; X, third direction. DETAILED DESCRIPTION

[0074] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0075] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0076] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0077] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0078] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0079] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0080] In the embodiments of this application, "parallel" includes not only absolute parallelism but also approximately parallelism as commonly understood in engineering practice. Similarly, "perpendicular" also includes not only absolute perpendicularity but also approximately perpendicularity as commonly understood in engineering practice. For example, if the angle between two directions is 85°-90°, they are considered perpendicular; if the angle between two directions is 0°-5°, they are considered parallel.

[0081] The term "plurality" used in this application refers to two or more (including two).

[0082] In the embodiment of the present application, the battery cell 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 is discharged.

[0083] The battery cell 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., and the embodiments of the present application are not limited to this.

[0084] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode sheet and a negative electrode sheet. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed back and forth between the positive and negative electrode sheets.

[0085] In some embodiments, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.

[0086] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0087] 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 or stainless steel with a silver surface treatment, 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.).

[0088] As an example, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to 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 manganese iron phosphate, and a composite material of lithium manganese iron 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 LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0089] In some embodiments, the negative electrode sheet 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.

[0090] 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.).

[0091] 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.

[0092] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells 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 batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0093] 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.

[0094] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode sheet and the negative electrode sheet. The separator can prevent the positive and negative electrodes from short-circuiting while allowing active ions to pass through.

[0095] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0096] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0097] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode, and serves to transport ions and isolate the positive and negative electrodes.

[0098] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0099] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0100] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0101] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be an ether solvent. Ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0102] The gel electrolyte consists of a polymer-based electrolyte framework network, combined with an ionic liquid-lithium salt.

[0103] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0104] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0105] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0106] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0107] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0108] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0109] As an example, the battery cell can be a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, and a polygonal battery cell. The polygonal battery cell is, for example, a hexagonal battery cell, etc. There is no special limitation in this application.

[0110] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0111] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0112] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0113] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0114] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0115] During the battery charging process, the battery cells generate heat. This heat easily accumulates, causing the temperature of the battery cells to rise. Generally, when the operating temperature of the battery cells is generally between 20 and 40 degrees, the charge and discharge performance and cycle life of the battery cells are better.

[0116] In some embodiments, the battery includes a heat exchange plate. When the heat exchange medium flows through the heat exchange plate, it can exchange heat with the battery cells through the heat exchange plate to adjust the temperature of the battery cells so that the battery cells can be charged and discharged within a suitable temperature range.

[0117] In some embodiments, the electrode assembly typically includes tabs, including positive and negative tabs. The positive and negative tabs can conduct current from the electrode assembly. The electrode assembly typically includes multiple positive and negative tabs, with the multiple positive tabs stacked and the multiple negative tabs stacked.

[0118] When charging or discharging, when current passes through the tab, the tab will generate heat; the heat exchange plate can exchange heat with the tab through the outer shell to reduce the temperature of the tab.

[0119] In some embodiments, the electrode sheets (positive electrode sheets or negative electrode sheets) are formed into multiple electrode sheet layers by winding or folding; in order to improve the flow capacity, electrode tabs can be provided on each electrode sheet layer.

[0120] However, there are many layers of tabs, and the heat dissipation efficiency of multiple tabs will vary depending on the position of the heat exchange plate. Therefore, the temperature at different positions of the electrode assembly will vary greatly due to the number and position of the tabs, thereby affecting the impedance of the electrode assembly, reducing the consistency of the current distribution of the electrode assembly, and affecting the charge and discharge performance and cycle life of the battery cell.

[0121] In view of this, an embodiment of the present application provides a technical solution, which reduces the temperature difference between different areas of the electrode assembly, reduces the impedance difference between different areas of the electrode assembly, improves the current consistency, improves the charge and discharge performance of the battery cell, and extends the cycle life of the battery cell by arranging heat exchange plates on both sides of the battery cell and removing part of the electrode ears in the middle of the electrode assembly.

[0122] The battery described in the embodiments of the present application is suitable for use in electrical devices that use the battery.

[0123] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0124] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0125] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0126] As shown in FIG1 , a battery 2 is provided inside the vehicle 1. The battery 2 may be provided at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1. For example, the battery 2 may serve as an operating power source for the vehicle 1.

[0127] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0128] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0129] Figure 2 is an exploded view of a battery according to some embodiments of the present invention. As shown in Figure 2, the battery 2 includes a housing 5 and a battery cell 6, which is contained within the housing 5. The battery cell 6 is the smallest unit of the battery.

[0130] The housing 5 is used to accommodate the battery cells 6 and can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b overlap each other and together define a storage space 5c for accommodating the battery cells 6. The second housing portion 5b can be a hollow structure with one end open. The first housing portion 5a is a plate-like structure, and the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. The first housing portion 5a and the second housing portion 5b can also both be hollow structures with one end open. The open side of the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0131] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0132] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0133] In the battery 2, there can be one or more battery cells 6. If there are multiple battery cells 6, the multiple battery cells 6 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections within the multiple battery cells 6. The multiple battery cells 6 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 6 can be housed within the housing 5. Alternatively, multiple battery cells 6 can be first connected in series, in parallel, or in a hybrid connection to form a battery module, and then the multiple battery modules can be connected in series, in parallel, or in a hybrid connection to form a single unit and housed within the housing 5.

[0134] Figure 3 is a schematic cross-sectional view of a battery provided in some embodiments of the present application; Figure 4 is an exploded schematic view of a battery cell provided in some embodiments of the present application; Figure 5 is an enlarged schematic view of the box in Figure 3; Figure 6 is an enlarged schematic view of the box in Figure 5; Figure 7 is a structural schematic view of an electrode assembly provided in some embodiments of the present application; and Figure 8 is a schematic cross-sectional view of Figure 7 taken along the EE direction.

[0135] 3 to 8 , an embodiment of the present application provides a battery 2 , which includes a battery cell 6 . The battery cell 6 includes a housing 20 and an electrode unit 30 accommodated in the housing 20 .

[0136] The number of battery cells 6 may be one or more.

[0137] The housing 20 is a hollow structure, and a space is formed inside the housing to accommodate the electrode unit 30. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly. For example, if the electrode assembly is a rectangular parallelepiped structure, a rectangular housing can be selected.

[0138] As an example, the housing 20 includes a shell 21 and an end cover 22 . The shell 21 has an opening, and the end cover 22 is used to cover the opening.

[0139] The housing 21 is a component used to cooperate with the end cover 22 to form an internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate an electrode assembly, an electrolyte, and other components.

[0140] The housing 21 and the end cap 22 may be separate components. For example, an opening may be provided on the housing 21 , and the end cap 22 may be placed over the opening to form an internal cavity of the battery cell 6 .

[0141] The housing 21 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 21 can be determined based on the specific shape and size of the electrode assembly. The housing 21 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, and aluminum alloy, and this embodiment of the present application does not impose any particular limitations on this.

[0142] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (e.g., copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 22 is less likely to deform when subjected to compression or collision, thereby providing the battery cell 6 with higher structural strength and improved reliability.

[0143] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0144] The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be open at one end, with one end cap 22 provided to cover the housing 21. In other examples, the housing 21 may be open at both ends, with two end caps 22 provided to cover the two openings of the housing 21, respectively.

[0145] In some embodiments, the electrode unit 30 includes multiple first electrode sheet layers 111. The multiple first electrode sheet layers 111 have the same polarity and are stacked along the first direction Y. A portion of the first electrode sheet layers 111 is provided with a first electrode tab 111a to form two first electrode tab groups 111b. Each first electrode tab group 111b includes multiple stacked and connected first electrode tabs 111a. A first electrode sheet layer 111 without a first electrode tab 111a is provided between the two first electrode tab groups 111b.

[0146] The first electrode layer 111 may be of positive polarity or negative polarity.

[0147] The electrode unit 30 is a component in the battery cell 6 where electrochemical reactions occur. Exemplarily, the electrode unit 30 includes one or more electrode assemblies 10. The electrode assembly 10 includes a first electrode sheet 11 and a second electrode sheet 12 having opposite polarities. Each first electrode sheet 11 is formed into at least two first electrode sheet layers 111 by winding or folding. When the first electrode sheet 11 is formed into at least two first electrode sheet layers 111 by winding or folding, the first electrode sheet 11 also forms a bending layer 112 at the bent position, and the bending layer 112 connects the first electrode sheet layers 111. The first electrode sheet 11 can be a positive electrode sheet or a negative electrode sheet.

[0148] Among all the first pole piece layers 111 , a portion of the first pole piece layers 111 are provided with first pole tabs 111 a , while the remaining portion of the first pole piece layers 111 are not provided with first pole tabs 111 a .

[0149] The multiple first tabs 111 a of each first tab group 111 b may be connected by welding, bonding or other processes.

[0150] A first pole sheet layer 111 without a first pole tab 111a is provided between the two first pole tab groups 111b. This can be understood as a first pole sheet layer without a first pole tab being provided between the two first pole sheet layers corresponding to the two first pole tab groups.

[0151] The numbers of the first electrode tabs 111 a in the two first electrode tab groups 111 b may be the same or different.

[0152] Exemplarily, the electrode unit 30 includes j first electrode tabs 111a. Along the first direction Y, the first electrode tabs 111a may be numbered as the 1st first electrode tab, the 2nd first electrode tab, ..., the i-th first electrode tab, the i+1th first electrode tab, ..., the j-th first electrode tab, where i and j are both positive integers, and i ≥ 2, j ≥ i+2. One first electrode tab group 111b includes the 1st to i-th first electrode tabs, and another first electrode tab group 111b includes the i+1th to j-th first electrode tabs. A first electrode layer 111 without a first electrode tab is provided between the first electrode layer 111 corresponding to the i-th first electrode tab and the first electrode layer 111 corresponding to the i+1th first electrode tab.

[0153] The outer side of the first pole piece layer 111 provided with the first first pole tab may have a first pole piece layer 111 without a first pole tab, or may not have a first pole piece layer 111 without a first pole tab, that is, a first pole piece layer without a first pole tab may be provided between the shell wall closest to the first first pole tab along the first direction Y and the first first pole tab, or the first pole piece layer provided with the first first pole tab is the outermost first pole piece layer of the electrode unit.

[0154] The outer side of the first pole piece layer 111 provided with the j-th first pole ear may have a first pole piece layer 111 without the first pole ear 111a, or may not have a first pole piece layer 111 without the first pole ear 111a, that is, there may be a first pole piece layer without the first pole ear between the shell wall closest to the j-th first pole ear along the first direction Y and the j-th first pole ear, or the first pole piece layer provided with the j-th first pole ear is the outermost first pole piece layer of the electrode unit.

[0155] Two adjacent first electrode tabs 111a of the first electrode tab group 111b may be arranged on two adjacent first electrode sheet layers 111, or may be arranged on two non-adjacent first electrode sheet layers 111. In other words, between two adjacent first electrode tabs 111a of the first electrode tab group 111b, there may be a first electrode sheet layer 111 without a first electrode tab 111a, or there may be no first electrode sheet layer 111 without a first electrode tab 111a.

[0156] The two first electrode tab groups 111b are electrically connected to electrically connect all the first electrode layers 111. For example, the two first electrode tab groups 111b can be directly connected or indirectly connected through other conductive structures (such as electrode terminals described below).

[0157] In some embodiments, the battery 2 further includes a plurality of heat exchange plates 7 arranged along a first direction Y. The housing 20 is disposed between adjacent heat exchange plates 7 and is capable of exchanging heat with the heat exchange plates 7. In the first direction Y, each first electrode layer 111 at least partially overlaps with the heat exchange plates 7. The heat exchange plates 7 can be used to regulate the temperature of the battery cells 6. For example, the heat exchange plates 7 have flow channels within them, through which a heat exchange medium can flow and exchange heat with the housing 20 through the heat exchange plates 7.

[0158] The multiple heat exchange plates 7 may be heat exchange plates of an integral design; the multiple heat exchange plates 7 may also be separately arranged, and the flow channels of the multiple heat exchange plates 7 may be connected or not connected.

[0159] One battery cell 6 or multiple battery cells 6 can be disposed between adjacent heat exchange plates 7. For example, multiple battery cells 6 arranged in sequence can be disposed between adjacent heat exchange plates 7, and the arrangement direction of the multiple battery cells 6 is perpendicular to the first direction Y.

[0160] The projection of the first pole piece layer 111 along the first direction Y and the projection of the heat exchange plate 7 along the first direction Y at least partially overlap.

[0161] In the embodiment of the present application, the heat exchange plates 7 located on both sides of the housing 20 are respectively disposed near the two first electrode tab groups 111b. During the charge and discharge process of the battery 2, the heat exchange plates 7 can absorb the heat generated by the two first electrode tab groups 111b through the housing 20, thereby reducing the temperature rise of each first electrode tab 111a and reducing the temperature difference between the multiple first electrode layers 111. The first electrode layer 111 located between the two first electrode tab groups 111b is not provided with a first electrode tab 111a. Therefore, even if the first electrode layer 111 located between the two first electrode tab groups 111b is farther away from the heat exchange plates 7, the temperature rise of the first electrode layer 111 located between the two first electrode tab groups 111b is relatively small, thereby reducing the temperature difference between the multiple first electrode layers 111. The embodiment of the present application simultaneously arranges heat exchange plates 7 on both sides of the shell 20 and removes part of the first pole ear 111a in the middle of the electrode unit 30 to reduce the temperature difference and impedance difference of different first pole piece layers 111, improve the current consistency, improve the charging and discharging performance of the battery cell 6, and extend the cycle life of the battery cell 6.

[0162] In some embodiments, a plurality of battery cells 6 arranged in sequence are provided between adjacent heat exchange plates 7 , and an arrangement direction of the plurality of battery cells 6 between adjacent heat exchange plates 7 is perpendicular to the first direction Y.

[0163] Optionally, the arrangement direction of the plurality of battery cells 6 may be parallel to the second direction Z, or may be parallel to the third direction X. The first direction Y, the second direction Z, and the third direction X are perpendicular to each other.

[0164] The heat exchange plate 7 of the embodiment of the present application can exchange heat with multiple battery cells 5 at the same time, thereby improving the heat exchange efficiency and simplifying the structure of the battery.

[0165] In some embodiments, the total number of first electrode sheet layers 111 is N, the number of first electrode tabs 111 a in each first electrode tab group 111 b is K1, and K1 and N satisfy: 1 / 4≤K1 / N≤7 / 16.

[0166] As an example, N is a positive integer and is greater than j.

[0167] In the embodiment of the present application, the number K1 of the first tabs 111a of the two first tab groups 111b can be the same or different. For example, the number K1 of the first tabs 111a of one first tab group 111b is equal to i, and the number K1 of the first tabs 111a of the other first tab group 111b is equal to ji. Ji can be equal to i or different from i.

[0168] Although the number K1 of the first tabs 111 a in the two first tab groups 111 b may be different, the number K1 of the first tabs 111 a in each first tab group 111 b satisfies 1 / 4≤K1 / N≤7 / 16.

[0169] Optionally, K1 / N is 1 / 4, 9 / 32, 5 / 16, 11 / 32, 6 / 16, 13 / 32 or 7 / 16.

[0170] In this embodiment of the present application, K1 / N is limited to greater than or equal to 1 / 4. This can increase the total number of first electrode tabs 111a, improve the current capacity of the electrode assembly 10, reduce the current and temperature rise of each first electrode tab 111a, and improve the fast charging capability of the battery cell 6. In this embodiment of the present application, K1 / N is limited to less than or equal to 7 / 16. This can reduce the number of first electrode tabs 111a away from the heat exchange plate 7 in the first direction Y, thereby reducing the temperature and impedance differences among the multiple first electrode sheet layers 111 and improving current consistency.

[0171] In some embodiments, 5 / 16≤K1 / N≤7 / 16, thereby further balancing the current capacity of the electrode assembly 10 and the temperature difference between the first electrode layer 111, improving the current consistency of the electrode assembly 10, enhancing the fast charging capability of the battery cell 6, and extending the cycle life of the battery cell 6.

[0172] In some embodiments, K1 / N may be 6 / 16.

[0173] In some embodiments, the number of first tabs 111 a in the two first tab groups 111 b is the same. Exemplarily, the first tabs 111 a in the two first tab groups 111 b are symmetrically distributed.

[0174] In some embodiments, any two adjacent first tabs 111a of the first tab group 111b are disposed on two adjacent first electrode layers 111. This embodiment of the application can make the multiple first tabs 111a of the first tab group 111b more concentrated, thereby reducing the temperature difference of the first electrode layer 111.

[0175] In some embodiments, the number of first electrode sheet layers 111 located between two first electrode tab groups 111 b and without first electrode tabs 111 a is K2, and K2 and N satisfy: 1 / 8≤K2 / N≤1 / 2.

[0176] Exemplarily, 2×K1+K2≤N.

[0177] Illustratively, K2 / N may be 1 / 8, 3 / 16, 4 / 16, 5 / 16, 6 / 16, 7 / 16, or 1 / 2.

[0178] In this embodiment of the present application, K2 / N is limited to less than or equal to 1 / 2. This allows for a larger number of first electrode tabs 111a provided in the electrode unit 30, thereby increasing the total number of first electrode tabs 111a, improving the current capacity of the electrode assembly 10, reducing the current and temperature rise of each first electrode tab 111a, and enhancing the fast-charging capability of the battery cell 6. In this embodiment of the present application, K2 / N is limited to greater than or equal to 1 / 8. This reduces the number of first electrode tabs 111a located away from the heat exchange plate 7 in the first direction Y, thereby reducing temperature and impedance differences among the multiple first electrode tabs 111a and improving current consistency.

[0179] In some embodiments, 1 / 8≤K2 / N≤3 / 8, thereby further balancing the current capacity of the electrode assembly 10 and the temperature difference between the first electrode layer 111, improving the current consistency of the electrode assembly 10, enhancing the fast charging capability of the battery cell 6, and extending the cycle life of the battery cell 6.

[0180] In some embodiments, the housing 20 includes two first shell walls 211 disposed opposite each other along a first direction Y. Each first shell wall 211 is configured to exchange heat with the heat exchange plate 7. In the first direction Y, the minimum distance between the outer surface 211a of the first shell wall 211 and the first tab 111a closest to the first shell wall 211 is D1 mm. K1, N, and D1 satisfy the following: 21 ≤ 88 × K1 / N - D1 / 5 ≤ 38.4.

[0181] The outer surface 211a of the first shell wall 211 can directly contact the heat exchange plate 7. Alternatively, a heat conductive structure (such as heat conductive glue) can be provided between the outer surface 211a of the first shell wall 211 and the heat exchange plate 7 to conduct heat between the first shell wall 211 and the heat exchange plate 7.

[0182] For example, D1 may be the distance in the first direction Y between the root of the first electrode tab 111 a closest to the first casing wall 211 and the first casing wall 211 .

[0183] Alternatively, 88×K1 / N-D1 / 5 may be 21, 22, 23, 24, 25, 25.5, 26, 26.9, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 38.1, 38.3 or 38.4.

[0184] D1 affects the heat transfer efficiency between the heat exchange plate 7 and the first tab 111a. As can be understood, the smaller D1 is, the shorter the heat transfer path between the heat exchange plate 7 and the first tab 111a is, the higher the heat transfer efficiency between the heat exchange plate 7 and the first tab 111a is, and the lower the temperature rise of the first tab 111a is.

[0185] In the embodiment of the present application, 88×K1 / N-D1 / 5 is limited to be greater than or equal to 21 to increase the number of first pole tabs 111a or shorten the heat conduction path between the first pole tab 111a and the heat exchange plate 7, thereby reducing heat generation by the first pole tab 111a, lowering the temperature rise of the first pole tab 111a, and improving the charge and discharge performance of the battery cell 6. In the embodiment of the present application, 88×K1 / N-D1 / 5 is limited to be less than or equal to 38.4 to reduce the difference between the heat conduction path between the innermost first pole tab 111a of the first pole tab group 111b and the heat exchange plate 7 and the heat conduction path between the outermost first pole tab 111a of the first pole tab group 111b and the heat exchange plate 7, thereby reducing the maximum temperature difference between the multiple first pole sheet layers 111, improving the current consistency of the electrode assembly 10, enhancing the fast charging capability of the battery cell 6, and extending the cycle life of the battery cell 6.

[0186] In some embodiments, 26.9≤88×K1 / N-D1 / 5≤38.3, thereby further balancing the temperature rise and temperature difference of the multiple first tabs 111a, improving the current consistency of the electrode assembly 10, enhancing the charge and discharge performance of the battery cell 6, and extending the cycle life of the battery cell 6.

[0187] In some embodiments, the housing 20 includes two first shell walls 211 disposed opposite each other along a first direction Y. Each first shell wall 211 is configured to exchange heat with the heat exchange plate 7. In the first direction Y, the minimum distance D1 between the outer surface 211a of the first shell wall 211 and the first tab 111a closest to the first shell wall 211 is 0.5-5 mm.

[0188] In this embodiment of the present application, D1 is limited to greater than or equal to 0.5 to ensure that the thickness and strength of the first shell wall 211 meet the requirements and improve the reliability of the battery cell 6. In this embodiment of the present application, D1 is limited to less than or equal to 5 to shorten the heat conduction path between the first electrode tab 111a and the heat exchange plate 7, reduce the heat generated by the first electrode tab 111a, reduce the temperature rise of the first electrode tab 111a, and improve the charge and discharge performance of the battery cell 6.

[0189] Alternatively, D1 may be 0.5, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0190] In some embodiments, D1 is 1-3 to further balance the reliability of the battery cell 6 and the charge and discharge performance of the battery cell 6 .

[0191] In some embodiments, the housing 20 may be a square housing.

[0192] In some embodiments, the housing 20 includes two first walls 211 that are opposite each other along a first direction Y, two second walls 212 that are opposite each other along a second direction Z, and two third walls 213 that are opposite each other along a third direction X. The first direction Y, the second direction Z, and the third direction X are perpendicular to each other. The area of ​​the first wall 211 is greater than that of the second wall 212, and the area of ​​the first wall 211 is greater than that of the third wall 213.

[0193] The first shell wall 211 is a shell wall with a larger area of ​​the outer shell 20. By using the first shell wall 211 to exchange heat with the heat exchange plate 7, the heat exchange area can be increased, the heat exchange efficiency can be improved, the temperature difference between different areas of the electrode assembly 10 can be reduced, and the charging and discharging performance of the battery cell 6 can be improved.

[0194] In some embodiments, the outer surface 211 a of the first shell wall 211 is a plane perpendicular to the first direction Y. Optionally, the first shell wall 211 is a flat plate structure perpendicular to the first direction Y.

[0195] In some embodiments, the housing 20 includes a shell 21 and an end cap 22. The shell 21 has an opening at one end along the second direction Z, and the end cap 22 covers the opening. For example, the shell 21 includes two first shell walls 211, two third shell walls 213, and a bottom wall opposite the end cap 22 along the second direction Z. The two second shell walls 212 can be the bottom wall 214 and the end cap 22, respectively.

[0196] In some embodiments, the two first tab groups 111 b are spaced apart along the first direction Y. Ends of the two first tab groups 111 b are bent toward each other and are oppositely disposed along the first direction Y.

[0197] By bending the two first tab groups 111 b , space can be saved and space utilization can be improved.

[0198] For example, the first electrode tab 111a may be disposed at an end of the first electrode layer 111 along the second direction Z. By bending the two first electrode tab groups 111b, the space occupied by the first electrode tab groups 111b in the second direction Z may be reduced, thereby improving space utilization.

[0199] In some embodiments, the battery cell 6 further includes an electrode terminal 40 , which is electrically connected to the two first electrode tab groups 111 b , so that all the first electrode sheet layers 111 are electrically connected to the electrode terminal 40 .

[0200] In some embodiments, the electrode terminal 40 is directly connected to the first tab group 111b. For example, the plurality of first tabs 111a of the first tab group 111b are stacked on the electrode terminal 40 and welded to the electrode terminal 40. The two first tab groups 111b are connected to different positions of the electrode terminal 40.

[0201] Exemplarily, the electrode terminal 40 includes two connecting portions arranged along the first direction Y, and the two first electrode tab groups 111 b are respectively connected to the two connecting portions.

[0202] In other embodiments, the electrode terminal 40 is connected to the two first tab groups 111b via a transition piece. Exemplarily, the transition piece includes a terminal connection portion and two tab connection portions, the terminal connection portion is connected to the electrode terminal 40, and the two tab connection portions are spaced apart along the first direction Y and connected to the terminal connection portion.

[0203] The two first tab groups 111 b are respectively connected to the two tab connecting portions.

[0204] In some embodiments, the middlemost first electrode layer 111 among the multiple first electrode layer 111 is not provided with a first electrode tab 111a, and the first electrode layers 111 corresponding to the two first electrode tab groups 111b are respectively located on both sides of the middlemost first electrode layer 111.

[0205] Exemplarily, when the number of first pole piece layers 111 is odd, there is one first pole piece layer 111 in the middle; and when the number of first pole piece layers 111 is even, there are two first pole piece layers 111 in the middle.

[0206] Among all the first electrode sheet layers 111, the middle-most first electrode sheet layer 111 is farthest from the heat exchange plate 7. In the embodiment of the present application, the middle-most first electrode sheet layer 111 is not provided with the first electrode tab 111a. This can reduce the temperature rise of the middle-most first electrode sheet layer 111, reduce the temperature difference between the middle-most first electrode sheet layer 111 and the other first electrode sheet layers 111, and improve current consistency. The first electrode sheet layers 111 corresponding to the two first electrode tab groups 111b are arranged on both sides of the middle-most first electrode sheet layer 111. This can shorten the heat conduction path between each first electrode tab group 111b and the corresponding heat exchange plate 7, thereby reducing the temperature rise of each first electrode tab 111a and reducing the temperature difference between the two first electrode tab groups 111b, thereby improving the charge and discharge capacity of the battery cell 6.

[0207] In some embodiments, each first electrode layer 111 includes a electrode body 111c, and a portion of the first electrode layers 111 is provided with a first electrode tab 111a extending from an end of the electrode body 111c along the second direction Z. Exemplarily, the electrode body 111c is a straight structure, and the first direction Y may be the stacking direction of the electrode bodies 111c of the plurality of first electrode layers 111. Optionally, the electrode bodies 111c are perpendicular to the first direction Y.

[0208] In some embodiments, the electrode unit 30 includes at least one electrode assembly 10, each electrode assembly 10 including a first electrode sheet 11 and a second electrode sheet 12 of opposite polarity. The first electrode sheet 11 includes at least a portion of a plurality of first electrode sheet layers 111, and the plurality of first electrode sheet layers 111 of the first electrode sheet 11 form at least one first electrode tab group 111b.

[0209] Exemplarily, the electrode unit 30 includes one electrode assembly 10 or two electrode assemblies 10. When the electrode unit 30 includes one electrode assembly 10, the first electrode sheet 11 may include all of the first electrode sheet layer 111; when the electrode unit 30 includes two electrode assemblies 10, the first electrode sheet 11 of one electrode assembly 10 may include a portion of the first electrode sheet layer 111, and the first electrode sheet 11 of the other electrode assembly 10 may include the remaining portion of the first electrode sheet layer 111. Correspondingly, the first electrode sheets 11 of the two electrode assemblies 10 respectively form two first electrode tab groups 111b.

[0210] The first pole piece 11 can be formed into at least two first pole piece layers 111 by winding, folding or other methods.

[0211] In the embodiment of the present application, the first electrode piece 11 is a continuously arranged whole. Therefore, the first electrode piece layer 111 without the first electrode tab 111 a can conduct current through the first electrode piece layer 111 provided on the first electrode tab 111 a.

[0212] In some embodiments, the first electrode sheet 11 and the second electrode sheet 12 are wound.

[0213] In some embodiments, the first pole piece 11 , the second pole piece 12 and the separator 13 are wound along a winding direction. For example, as shown in FIG. 7 , the winding direction may be counterclockwise.

[0214] In some embodiments, the first pole piece 11 includes a bending layer 112, and the bending layer 112 connects two adjacent first pole piece layers 111 along the winding direction. Exemplarily, the bending layer 112 is connected to the pole piece body 111c.

[0215] In some embodiments, the electrode assembly 10 includes a straight region 10a and two bending regions 10b, which are located on both sides of the straight region 10a along the third direction X. The bending layer 112 of the first electrode 11 may be located in the bending region 10b, and the electrode body 111c is located in the straight region 10a.

[0216] The dimension of the flat region 10a along the third direction X may be W. For example, the number of first pole piece layers 111 is counted based on the dimension in the third direction X exceeding 0.5W. In other words, the dimension of the first pole piece layer 111 along the third direction X must be at least greater than 0.5W.

[0217] In some embodiments, the electrode unit 30 includes two electrode assemblies 10 , and the two electrode assemblies 10 are arranged along the first direction Y. Each electrode assembly 10 includes a first electrode tab group 111 b .

[0218] Illustratively, each electrode assembly 10 includes a first electrode sheet 11 , and each first electrode sheet 11 includes a first electrode tab group 111 b .

[0219] Providing two electrode assemblies 10 can reduce the number of first electrode sheet layers 111 of a single electrode assembly 10 and reduce the risk of misalignment of the first electrode tab 111 a during the molding process of the electrode assembly 10 .

[0220] In some embodiments, the two electrode assemblies 10 have the same number of first electrode layer 111 layers.

[0221] In some embodiments, the two electrode assemblies 10 are symmetrical about a plane perpendicular to the first direction Y.

[0222] In some embodiments, the electrode unit 30 includes multiple second electrode sheet layers 121. The polarity of the second electrode sheet layers 121 is opposite to that of the first electrode sheet layer 111. The second electrode sheet layers 121 and the first electrode sheet layer 111 are stacked along the first direction Y. A portion of the second electrode sheet layers 121 is provided with second electrode tabs 121a to form two second electrode tab groups 121b. Each second electrode tab group 121b includes multiple stacked and connected second electrode tabs 121a. A second electrode sheet layer 121 without a second electrode tab 121a is provided between the two second electrode tab groups 121b.

[0223] Exemplarily, the second pole piece 12 is formed into at least two second pole piece layers 121 by winding or folding.

[0224] Among all the second pole piece layers 121 , a portion of the second pole piece layers 121 are provided with second pole tabs 121 a , while the remaining portion of the second pole piece layers 121 are not provided with second pole tabs 121 a .

[0225] The plurality of second electrode tabs 121 a of each second electrode tab group 121 b may be connected by welding, bonding or other processes.

[0226] The numbers of the second electrode tabs 121 a in the two second electrode tab groups 121 b may be the same or different.

[0227] The two second electrode tab groups 121b are electrically connected to electrically connect all the second electrode layer 121. For example, the two second electrode tab groups 121b can be directly connected or indirectly connected through other conductive structures.

[0228] The heat exchange plates 7 on either side of the housing 20 are positioned adjacent to the two second tab groups 121b. During the charge and discharge process of the battery 2, the heat exchange plates 7 absorb heat generated by the two second tab groups 121b through the housing 20, thereby reducing the temperature rise of each second tab 121a and lowering the temperature difference between the two or more second tab layers. The second tab layer 121 located between the two second tab groups 121b is not provided with a second tab 121a. Therefore, even if the second tab layer 121 located between the two second tab groups 121b is farther from the heat exchange plates 7, the temperature rise of the second tab layer 121 located between the two second tab groups 121b is relatively small, thereby reducing the temperature difference between the multiple second tab layers 121. In this embodiment of the present application, by simultaneously providing heat exchange plates 7 on both sides of the housing 20 and removing a portion of the second tab 121a in the middle of the electrode unit, the temperature and impedance differences between different second tab layers 121 are reduced, thereby improving current consistency, the charge and discharge performance of the battery cell 6, and the cycle life of the battery cell 6.

[0229] In some embodiments, in the first direction Y, each second pole piece layer 121 at least partially overlaps with the heat exchange plate 7 .

[0230] In some embodiments, the total number of the second electrode sheet layers 121 is M, the number of the second electrode tabs 121 a in each second electrode tab group 121 b is K3, and K3 and M satisfy: 1 / 4≤K3 / M≤7 / 16.

[0231] M and N may be the same or different.

[0232] The number K3 of the second tabs 121a in the two second tab groups 121b can be the same or different. Although the number K3 of the second tabs 121a in the two second tab groups 121b can be different, the number K3 of the second tabs 121a in each second tab group 121b satisfies 1 / 4≤K3 / M≤7 / 16.

[0233] Optionally, K3 / M is 1 / 4, 9 / 32, 5 / 16, 11 / 32, 6 / 16, 13 / 32 or 7 / 16.

[0234] In this embodiment of the present application, K3 / M is limited to greater than or equal to 1 / 4. This can increase the total number of second electrode tabs 121a, improve the current capacity of the electrode assembly 10, reduce the current and temperature rise of each second electrode tab 121a, and improve the fast charging capability of the battery cell 6. In this embodiment of the present application, K3 / M is limited to less than or equal to 7 / 16. This can reduce the number of second electrode tabs 121a away from the heat exchange plate 7 in the first direction Y, thereby reducing the temperature and impedance differences among the multiple second electrode sheet layers 121 and improving current consistency.

[0235] In some embodiments, 5 / 16≤K3 / M≤7 / 16, thereby further balancing the current capacity of the electrode assembly 10 and the temperature difference between the second electrode layer 121, improving the current consistency of the electrode assembly 10, enhancing the fast charging capability of the battery cell 6, and extending the cycle life of the battery cell 6.

[0236] In some embodiments, the two second tab groups 121 b have the same number of second tabs 121 a .

[0237] In some embodiments, any two adjacent second tabs 121a of the second tab group 121b are disposed on two adjacent second electrode layers 121. This embodiment of the application can make the plurality of second tabs 121a of the second tab group 121b more concentrated, thereby reducing the temperature difference of the second electrode layer 121.

[0238] In some embodiments, the number of second electrode layer 121 located between two second electrode tab groups 121 b and without second electrode tabs 121 a is K4, and K4 and M satisfy: 1 / 8≤K4 / M≤1 / 2.

[0239] Illustratively, K2 / N may be 1 / 8, 3 / 16, 4 / 16, 5 / 16, 6 / 16, 7 / 16, or 1 / 2.

[0240] In this embodiment of the present application, K4 / M is limited to less than or equal to 1 / 2. This allows for a larger number of second electrode tabs 121a provided in the electrode unit 30, thereby increasing the total number of second electrode tabs 121a, improving the current capacity of the electrode assembly 10, reducing the current and temperature rise of each second electrode tab 121a, and enhancing the fast charging capability of the battery cell 6. In this embodiment of the present application, K4 / M is limited to greater than or equal to 1 / 8. This reduces the number of second electrode tabs 121a located away from the heat exchange plate 7 in the first direction Y, thereby reducing temperature and impedance differences among the multiple second electrode tabs 121 and improving current consistency.

[0241] In some embodiments, 1 / 8≤K4 / M≤3 / 8, thereby further balancing the current capacity of the electrode assembly 10 and the temperature difference between the second electrode layer 121, improving the current consistency of the electrode assembly 10, enhancing the fast charging capability of the battery cell 6, and extending the cycle life of the battery cell 6.

[0242] In some embodiments, in the first direction Y, the minimum distance between the outer surface 211a of the first shell wall 211 and the second tab 121a closest to the first shell wall 211 is 0.5 mm to 5 mm. Alternatively, the minimum distance between the outer surface 211a of the first shell wall 211 and the second tab 121a closest to the first shell wall 211 is 1 mm to 3 mm.

[0243] In some embodiments, the first electrode tab 111a is a negative electrode tab, and the second electrode tab 121a is a positive electrode tab. The number of first electrode tabs 111a in the first electrode tab group 111b is greater than the number of second electrode tabs 121a in the second electrode tab group 121b.

[0244] In the embodiment of the present application, the number of the first pole tabs 111 a is different from the number of the second pole tabs 121 a , so that the positive electrode's and negative electrode's current carrying capacities can be designed differently as needed to meet design requirements.

[0245] In some embodiments, the first tab 111a is a copper tab, the second tab 121a is an aluminum tab, and the sum of the cross-sectional areas of all second tabs 121a is A1, in mm. 2 The sum of the cross-sectional areas of all first tabs 111a is A2, in mm. 2 .A1≤2.5A2.

[0246] The embodiment of the present application comprehensively considers the melting point, resistivity and flow area of ​​the copper and aluminum tabs, and limits A1 / A2 to less than or equal to 2.5. When the current is too large (for example, in a short circuit), the aluminum tab can be melted before the copper tab, thereby cutting off the circuit in time and reducing safety risks.

[0247] In some embodiments, A1≤1.5A2, so that the aluminum tabs can melt faster when the current is too large, while the aluminum tabs meet normal overcurrent requirements, thereby cutting off the circuit in time and reducing safety risks.

[0248] In some embodiments, the battery cell 6 may be a fast-charge battery cell.

[0249] In some embodiments, the average charging rate of the battery cells 6 is x, that is, the battery cells 6 can achieve xC fast charging. Optionally, x≥2, for example, x is 2, 3, 4, 5 or 6.

[0250] For example, taking 4C fast charging as an example, the battery cell 6 can be fast charged according to the following method:

[0251] (i) leaving the battery cell 6 at rest for 10 minutes, and then charging the battery cell 6 to 97% SOC (State of Charge) with an equivalent current of 4C;

[0252] (ii) After standing for 30 minutes, the battery cell 6 was discharged at a constant current of 1C to 3% SOC;

[0253] (iii) repeating steps (i) and (ii) 50 times;

[0254] (iv) charging the battery cell 6 to 97% SOC with an equivalent current of 4C;

[0255] (v) Disassemble the battery cell 6, and take the lithium-ion battery cell 6 as an example to observe the lithium deposition on the surface of the negative electrode. For example, flatten the negative electrode, measure the total area S1 of the negative active material layer on one side of the negative electrode; measure the maximum dimension a of each lithium deposition point on the negative active material layer (there is no lithium deposition around the lithium deposition point) along the length direction of the negative electrode, and measure the maximum dimension b of each lithium deposition point along the width direction of the negative electrode. Take a / 2 as the median value of the lithium deposition point in the length direction, and 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.

[0256] If a battery cell 6 is charged from SOC F1 to SOC F2 at a constant or variable current in just 1 / 4 hour, this current is called an equivalent 4C current. (For example, in the above test method, charging a battery cell 6 from 3% SOC to 97% SOC in just 15 minutes is called an equivalent 4C current.)

[0257] It can be understood that the test method of xC fast charging is the same as above, and the battery will be charged with an equivalent xC current.

[0258] In some embodiments, the first electrode 11 is a negative electrode. During fast charging of the battery cell 6, the first electrode tab 111a generates significant heat. By providing the heat exchange plate 7 and two first electrode tab groups 111b, the embodiment of the present application can reduce the temperature rise of the first electrode tab 111a during fast charging, improve the temperature consistency of the electrode assembly 10, and enhance the fast charging performance of the battery cell 6.

[0259] In some embodiments, the first electrode sheet 11 includes a negative electrode current collector 11 a and a negative electrode active material layer 11 b coated on a surface of the negative electrode current collector 11 a .

[0260] Illustratively, each first electrode layer 111 includes a portion of a negative electrode current collector 11a and a portion of a negative electrode active material layer 11b. The negative electrode current collector 11a includes a plurality of uncoated regions not coated with the active material layer, which may be the first electrode tabs 111a.

[0261] In some embodiments, the negative active material layer 11 b includes a negative active material, a binder, and a conductive agent.

[0262] In some embodiments, the coating weight per unit area of ​​the negative electrode active material layer 11b is less than or equal to 150 mg / 1540.25 mm 2 .

[0263] For example, a sample with the negative electrode active material layer 11b coated on only one side of the negative electrode sheet is cut out, and the sample is 1540.25 mm 2 Measure the sample's weight G1 in mg. Then, remove the negative electrode active material layer 11b from the sample and weigh the remaining negative electrode current collector 11a to obtain a weight G2 in mg. The coating weight per unit area of ​​the negative electrode active material layer 11b can be G1-G2.

[0264] In the embodiment of the present application, the coating weight per unit area of ​​the negative electrode active material layer 11b is small, and the negative electrode active material layer 11b can have a smaller thickness, thereby reducing the resistance of ions embedded in the negative electrode active material layer 11b during charging and improving the charging efficiency of the battery cell 6.

[0265] In some embodiments, the first electrode sheet 11 includes a negative electrode active material.

[0266] Illustratively, the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, silicon oxide, or silicon carbon.

[0267] In some embodiments, the volume distribution particle size of the negative electrode active material is Dv50 ≤ 15 μm. A smaller volume distribution particle size of the negative electrode active material provides more active reaction sites, allowing the negative electrode active material to receive ions more quickly, thereby improving the charging efficiency of the battery cell 6 and enhancing the fast charging capability of the battery cell 6.

[0268] 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.

[0269] Alternatively, the volume distribution particle size Dv50 of the negative electrode active material may be 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 14 μm, or 15 μm.

[0270] In some embodiments, the volume distribution particle size Dv50 of the negative electrode active material is ≤ 10 μm.

[0271] In some embodiments, the specific surface area of ​​the negative electrode active material is 0.5 m 2 / g-5m 2 / g. Optionally, the specific surface area of ​​the negative electrode active material is 0.5m 2 / g、1m 2 / g, 1.5m 2 / g, 2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g or 5m 2 / g.

[0272] 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.

[0273] The embodiment of the present application 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 6 and improving the fast charging capability of the battery cell 6.

[0274] In some embodiments, the battery cell 6 further includes an electrolyte contained in the housing 20 , and the ionic conductivity of the electrolyte is 9 mS / cm-16 mS / cm.

[0275] 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.

[0276] Alternatively, the ionic conductivity of the electrolyte may be 9 mS / cm, 10 mS / cm, 11 mS / cm, 12 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, or 16 mS / cm.

[0277] The electrolyte of the embodiment of the present application has good ionic conductivity, which can reduce the impedance of the battery cell 6 and increase the migration rate of ions, thereby improving the charging efficiency of the battery cell 6 and improving the fast charging capability of the battery cell 6.

[0278] In some embodiments, the electrolyte includes a low-viscosity solvent to reduce resistance to ion migration.

[0279] In some embodiments, the direct current resistance (DCR) of the battery cell 6 is less than or equal to 0.4 milliohms.

[0280] For example, the DC impedance of the battery cell 6 can be measured according to the following method:

[0281] (i) At 25° C., a battery cell with a capacity of Cn (in Ah) is charged to 100% SOC at a current of 0.33 Cn (in A);

[0282] (ii) After standing for 30 min, the battery cell was discharged to 50% SOC at a current of 0.33 cm;

[0283] (iii) After standing for 60 minutes, the battery cell is discharged at a current of 4Cn (in A) for 30 seconds. The battery cell voltage before discharge (in mV) and the battery cell voltage at 10 seconds after discharge (in mV) are obtained.

[0284] (iv) Calculation shows that DCR = (V0-V1) / 4Cn.

[0285] In the embodiment of the present application, the battery cell 6 has a smaller DC impedance, thereby increasing the migration rate of ions, thereby improving the charging efficiency of the battery cell 6 and improving the fast charging capability of the battery cell 6.

[0286] In some embodiments, each first electrode layer 111 includes an electrode body 111 c, and a portion of the first electrode layer 111 is provided with a first electrode tab 111 a extending from an end of the electrode body 111 c along a second direction Z, where the second direction Z is perpendicular to the first direction Y. In the first direction Y, each electrode body 111 c at least partially overlaps with the heat exchange plate 7.

[0287] Exemplarily, the electrode body 111 c is provided with an active material layer. The thickness of the electrode body 111 c is greater than the thickness of the first electrode tab 111 a.

[0288] The electrode body 111c may be the portion of the first electrode layer 111 that reacts with the electrolyte. Heat generated by the first electrode tab 111a may be conducted through the electrode body 111c to the heat exchange plate 7. By adjusting the arrangement of the first electrode tabs 111a, the present embodiment can reduce the temperature difference between the multiple electrode bodies 111c, lowering the effect of temperature on the impedance of the electrode bodies 111c, improving current consistency, and enhancing the charge and discharge capabilities of the battery cell 6.

[0289] In some embodiments, the first tab 111a of the first tab group 111b closest to a first shell wall 211 can be called the outermost first tab. The distance between the root of the outermost first tab connected to the pole piece body 111c and the outer surface 211a of the corresponding first shell wall 211 is D1.

[0290] In some embodiments, in the second direction Z, the size of the heat exchange plate 7 is H1, the size of the pole piece body 111 c is H2, and 0.6≤H1 / H2≤1.2.

[0291] In this embodiment of the present application, H1 / H2 is set to be greater than or equal to 0.6 to increase the heat exchange area between the heat exchange plate 7 and the electrode body 111c, thereby increasing heat exchange efficiency, reducing temperature changes of the electrode body 111c during the charge and discharge process, and improving the charge and discharge capabilities of the battery cell 6. In this embodiment of the present application, H1 / H2 is set to be less than or equal to 1.2 to reduce the waste of heat exchange capacity of the heat exchange plate 7, reduce the weight and volume of the heat exchange plate 7, and increase the energy density of the battery 2.

[0292] Alternatively, H1 / H2 may be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 or 1.2.

[0293] In some embodiments, 0.8≤H1 / H2≤1.1, so as to further balance the heat exchange capacity and volume of the heat exchange plate 7. On the premise that the heat exchange capacity meets the requirements, the volume of the heat exchange plate 7 is reduced to improve the energy density of the battery 2.

[0294] In some embodiments, in the second direction Z, a distance between an edge of the electrode body 111 c close to the first electrode tab 111 a and an edge of the heat exchange plate 7 close to the first electrode tab 111 a is L1, and L1 is ≤ 20 mm.

[0295] For example, in the second direction Z, the edge of the heat exchange plate 7 close to the first electrode tab 111 a may extend beyond the electrode body 111 c or may not extend beyond the electrode body 111 c.

[0296] In the case where the edge of the electrode body 111c near the first electrode tab 111a extends beyond the edge of the heat exchange plate 7 near the first electrode tab 111a, the embodiment of the present application limits L1 to less than or equal to 20 mm. This allows the heat exchange plate 7 to be as close as possible to the connection between the first electrode tab 111a and the electrode body 111c. In other words, it allows the heat exchange plate 7 to be closer to the location with the highest temperature rise as quickly as possible, thereby reducing the temperature rise of the electrode assembly 10 and improving the cycling performance of the battery cell 6. In the case where the edge of the heat exchange plate 7 near the first electrode tab 111a extends beyond the edge of the electrode body 111c near the first electrode tab 111a, the embodiment of the present application limits L1 to less than or equal to 20 mm. This can reduce the excessive design of the heat exchange plate 7, reduce the space and weight of the heat exchange plate 7, and improve the energy density.

[0297] Alternatively, L1 may be 0 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, 13 mm, 15 mm, 18 mm, or 20 mm.

[0298] In some embodiments, L1 ≤ 15 mm, so as to further reduce the temperature rise of the electrode assembly 10 , improve the cycle performance of the battery cell 6 , and increase the energy density.

[0299] FIG9 is a schematic partial cross-sectional view of batteries provided in some other embodiments of the present application.

[0300] As shown in FIG. 9 , in some embodiments, in the second direction Z, the edge of the heat exchange plate 7 close to the first electrode tab 111 a extends beyond the edge of the electrode body 111 c close to the first electrode tab 111 a .

[0301] In the first direction Y, the heat exchange plate 7 can cover the connection between the main body and the first pole tab 111a, thereby shortening the heat transfer path between the first pole tab 111a and the heat exchange plate 7, reducing the temperature rise at the connection between the main body and the first pole tab 111a, and improving the cycle performance of the battery cell 6.

[0302] Alternatively, in some embodiments, in the second direction Z, the edge of the heat exchange plate 7 close to the first pole ear 111a is flush with the edge of the pole piece body 111c close to the first pole ear 111a, which can improve the heat exchange efficiency, reduce the size of the heat exchange plate 7, and increase the energy density.

[0303] FIG10 is a schematic diagram of an electrode assembly of a battery cell provided in some other embodiments of the present application.

[0304] As shown in Figure 10, in some embodiments, the electrode unit 30 includes an electrode assembly 10. The first electrode sheet 11 of the electrode assembly 10 includes all first electrode sheet layers 111. Correspondingly, the first electrode sheet 11 includes two first electrode tab groups 111b.

[0305] The second pole piece 12 includes all second pole piece layers 121 . Correspondingly, the second pole piece 12 includes two second pole tab groups 121 b .

[0306] In some embodiments, the electrode assembly 10 is a wound structure. The first electrode tab 111a is not provided on the innermost windings of the first electrode sheet 11. The second electrode tab 111a is not provided on the innermost windings of the second electrode sheet 12.

[0307] FIG11 is a schematic diagram of an electrode assembly of a battery cell provided in some other embodiments of the present application.

[0308] As shown in Figure 11, in some embodiments, the electrode assembly 10 includes multiple second electrode sheets 12, the first electrode sheet layer 111 and the second electrode sheet 12 of the first electrode sheet 11 are alternately arranged along the first direction Y, and the first electrode sheet 11 includes a bending layer 112, which connects two adjacent first electrode sheet layers 111.

[0309] The first pole piece 11 adopts a continuous bending structure to form a plurality of first pole piece layers 111 .

[0310] In some embodiments, the electrode unit 30 includes two electrode assemblies 10 .

[0311] In some embodiments, the plurality of second pole pieces 12 are independently provided, and each second pole piece 12 is provided with a second pole tab 121 a.

[0312] According to some embodiments of the present application, the present application further provides an electrical device comprising a battery according to any of the above embodiments, the battery being used to provide electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery.

[0313] 4 to 8 , an embodiment of the present application provides a battery 2 , which includes a heat exchange plate 7 and a battery cell 6 .

[0314] The battery cell 6 includes a housing 20 and two electrode assemblies 10 housed in the housing 20 . The two electrode assemblies 10 are arranged along a first direction Y. The electrode assemblies 10 include a first electrode sheet 11 and a second electrode sheet 12 that are wound together. The first electrode sheet 11 and the second electrode sheet 12 have opposite polarities.

[0315] Each first pole piece 11 includes 0.5N first pole piece layers 111 stacked along a first direction Y. K1 first pole piece layers 111 of the first pole piece 11 are provided with first pole tabs 111a, where K1 is less than 0.5N, N is a positive even number, and K1 is a positive integer greater than 1. The K1 first pole tabs 111a of each first pole piece 11 are stacked and connected to form a first pole tab group 111b.

[0316] Each first electrode sheet 11 further includes 0.5K2 first electrode sheet layers 111 without first electrode tabs 111a, where K2 is a positive even number. The 0.5K2 first electrode sheet layers 111 of one electrode assembly 10 are located on a side of the K1 first electrode sheet layers 111 closer to another electrode assembly 10 along the first direction Y.

[0317] 1 / 8≤K2 / N≤3 / 8, 5 / 16≤K1 / N≤7 / 16.

[0318] The plurality of heat exchange plates 7 are arranged along the first direction Y. The housing 20 is arranged between adjacent heat exchange plates 7 and is capable of exchanging heat with the heat exchange plates 7. In the first direction Y, each first pole piece layer 111 at least partially overlaps with the heat exchange plate 7.

[0319] The housing 20 includes two first shell walls 211 disposed opposite each other along a first direction Y. Each first shell wall 211 is configured to exchange heat with the heat exchange plate 7. In the first direction Y, the minimum distance D1 between the outer surface 211a of the first shell wall 211 and the first tab 111a closest to the first shell wall 211 is 0.5-5 mm.

[0320] Each first electrode layer 111 includes an electrode body 111c. A portion of the first electrode layer 111 is provided with a first electrode tab 111a extending from the end of the electrode body 111c along a second direction Z. The second direction Z is perpendicular to the first direction Y. In the first direction Y, each electrode body 111c at least partially overlaps with the heat exchange plate 7.

[0321] In the second direction Z, the size of the heat exchange plate 7 is H1, the size of the pole piece body 111 c is H2, and 0.8≤H1 / H2≤1.1.

[0322] Example

[0323] The following examples describe the present disclosure in more detail. These examples are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing. The instruments used in the examples are commercially available.

[0324] Example 1

[0325] (i) Graphite (a negative electrode active material) or a mixture of graphite and other active materials in different mass ratios, acetylene black (a conductive agent), CMC (a thickener), and SBR (a binder) are mixed in a mass ratio of 96.4:1:1.2:1.4, deionized water (a solvent) is added, and the mixture is stirred in a vacuum mixer until the mixture becomes uniform to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on a copper foil, dried at room temperature, and then transferred to an oven for further drying. The mixture is then cold pressed, slit, and cut into pieces to obtain a first electrode sheet.

[0326] (ii) The positive electrode active material NCM523, the conductive agent acetylene black, and the binder PVDF were mixed in a mass ratio of 96:2:2. NMP solvent was added and stirred in a vacuum mixer until the mixture was homogeneous to obtain a positive electrode slurry. The positive electrode slurry was evenly coated on copper foil, air-dried at room temperature, and then transferred to an oven for further drying. The second electrode sheet was then cold-pressed, slit, and cut into pieces. The positive electrode slurry solidified to form an active material layer.

[0327] (iii) Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and then fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0328] (iv) A 12 μm thick polypropylene film was used as the separator.

[0329] (v) The first electrode sheet, the separator, and the second electrode sheet are stacked together and wound into a flat electrode assembly.

[0330] (vi) The two electrode assemblies are placed in a housing, and then the battery cell is obtained through processes such as liquid injection, static standing, formation, and shaping.

[0331] (vii) Place the battery cell between two heat exchange plates and bond the heat exchange plates to the battery cell using thermally conductive adhesive.

[0332] In each electrode assembly of a battery cell, the first pole piece includes 0.5N first pole piece layers stacked along a first direction. The K1 first pole piece layers of the first pole piece are provided with a first pole tab, K1 is less than 0.5N, N is a positive even number, and K1 is a positive integer greater than 1. The K1 first pole tabs of each first pole piece are stacked and connected to form a first pole tab group. Each first pole piece also includes 0.5K2 first pole piece layers without a first pole tab, K2 is a positive even number. These 0.5K2 first pole piece layers of an electrode assembly are located on the side of the K1 first pole piece layers close to another electrode assembly along the first direction. K1 / N is 9 / 32, and K2 / N is 7 / 16.

[0333] In each electrode assembly of the battery cell, the second pole piece includes 0.5M second pole piece layers stacked along the first direction. The K3 second pole piece layers of the second pole piece are provided with second pole tabs, K3 is less than 0.5M, M is a positive even number, and K3 is a positive integer greater than 1. The K3 second pole tabs of each second pole piece are stacked and connected to form a second pole tab group. Each second pole piece also includes 0.5K4 second pole piece layers without second pole tabs, K4 is a positive even number. These 0.5K4 second pole piece layers of an electrode assembly are located on the side of the K3 second pole piece layers close to another electrode assembly along the first direction. K3 / M is 1 / 4, and K4 / M is 1 / 2.

[0334] In addition, referring to Figures 3-8, D1 is 0.7 mm and H1 / H2 is 1.

[0335] Example 2-12

[0336] The preparation methods of the batteries of Examples 2-12 can refer to Example 1. The differences between Examples 2-12 and Example 1 are shown in Table 1.

[0337] Comparative Example 1

[0338] The preparation method of the battery cell of Comparative Example 1 can refer to Example 1. The differences between Comparative Example 1 and Example 1 are shown in Table 1.

[0339] Test section

[0340] During battery cell preparation, temperature-sensing wires were placed at multiple detection points within the electrode assembly. These wires were capable of detecting and recording the actual temperature at each detection point within the battery cell during a 4C fast charge at 20°C. This allowed the maximum and minimum temperatures, as well as the maximum temperature difference, to be determined. During charging, cooling water at 20°C and a flow rate of 2 L / min flowed through the heat exchange plate. The data obtained for Examples 1-12 and Comparative Example 1 are shown in Table 1.

[0341] Figures 12 to 14 are schematic diagrams of battery cells of some embodiments of the present application at different angles, showing multiple detection sites. For example, detection sites P1, P2, and P3 are located between the two electrode assemblies 10 in the first direction Y, arranged from top to bottom in the second direction Z, and located in the middle of the electrode assembly 10 in the third direction X. Detection sites P4, P5, and P6 are located on the outside of the right electrode assembly 10 in Figure 12, arranged from top to bottom in the second direction Z, and located in the middle of the electrode assembly 10 in the third direction X. Detection site P7 is located at the center of the outer surface of the left electrode assembly 10 in Figure 12. Detection site P8 is located on the outer surface of the left electrode assembly 10 in Figure 12 and is located near the first tab group 111b. Detection site P9 is located on the outer surface of the left electrode assembly 10 and is located near the second tab group 121b.

[0342] Table 1

[0343] Referring to Table 1, Comparative Example 1 includes a first tab on each first electrode layer, resulting in a large maximum temperature difference within the battery cell. Referring to Comparative Example 1 and Examples 1-12, removing some of the first tabs from the electrode assembly can reduce the temperature difference, lower impedance variation, improve current consistency, enhance the charge and discharge performance of the battery cell, and extend the cycle life of the battery cell.

[0344] Referring to Examples 1-12, limiting K1 / N to 1 / 4-7 / 16 can reduce the maximum temperature difference. Further, limiting K1 / N to 5 / 16-7 / 16 can reduce the maximum temperature of the electrode assembly and reduce the temperature difference of the electrode assembly.

[0345] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A battery comprising: A battery cell, comprising a housing and an electrode unit contained in the housing, wherein the electrode unit comprises a plurality of first pole sheet layers, the plurality of first pole sheet layers have the same polarity and are stacked in a first direction, a portion of the first pole sheet layers are provided with first pole tabs and form two first pole tab groups, each of the first pole tab groups comprises a plurality of first pole tabs that are stacked and connected, and a first pole sheet layer without the first pole tab is provided between the two first pole tab groups; A plurality of heat exchange plates are arranged along the first direction, the housing is arranged between adjacent heat exchange plates and can exchange heat with the heat exchange plates, and in the first direction, each of the first pole piece layers at least partially overlaps with the heat exchange plates.

2. The battery according to claim 1, wherein The total number of the first pole sheet layers is N, the number of the first pole tabs of each first pole tab group is K1, and K1 and N satisfy: 1 / 4≤K1 / N≤7 / 16; Optionally, 5 / 16≤K1 / N≤7 / 16.

3. The battery according to claim 2, wherein The number of the first pole sheet layers located between the two first pole tab groups and not provided with the first pole tabs is K2, and K2 and N satisfy: 1 / 8≤K2 / N≤1 / 2; Optionally, 1 / 8≤K2 / N≤3 / 8.

4. The battery according to claim 2 or 3, wherein The housing comprises two first shell walls arranged opposite to each other along the first direction, each of the first shell walls being used for exchanging heat with the heat exchange plate; In the first direction, the minimum distance between the outer surface of the first shell wall and the first pole ear closest to the first shell wall is D1 mm; K1, N and D1 satisfy: 21≤88×K1 / N-D1 / 5≤38.4; optionally, 26.9≤88×K1 / N-D1 / 5≤38.

3.

5. The battery according to any one of claims 1 to 4, wherein: The housing comprises two first shell walls arranged opposite to each other along the first direction, each of the first shell walls being used for exchanging heat with the heat exchange plate; In the first direction, the minimum distance between the outer surface of the first shell wall and the first pole ear closest to the first shell wall is D1 mm; D1 is 0.5-5; optionally, D1 is 1-3.

6. The battery according to any one of claims 1 to 5, wherein: The two first electrode tab groups are spaced apart along the first direction; The ends of the two first electrode tab groups are bent in a direction approaching each other and the ends of the two first electrode tab groups are arranged opposite to each other along the first direction.

7. The battery according to any one of claims 1 to 6, wherein: The first pole sheet layer in the middle of the plurality of first pole sheet layers is not provided with the first pole tab, and the first pole sheet layers corresponding to the two first pole tab groups are respectively located on both sides of the first pole sheet layer in the middle.

8. The battery according to any one of claims 1 to 7, wherein: The electrode unit comprises at least one electrode assembly, each of which comprises a first electrode piece and a second electrode piece with opposite polarities; The first pole piece includes at least part of the plurality of first pole piece layers, and the plurality of first pole piece layers of the first pole piece form at least one first pole lug group.

9. The battery according to claim 8, wherein The first pole piece and the second pole piece are wound; or The electrode assembly includes a plurality of second pole sheets, the first pole sheet layers and the second pole sheets of the first pole sheet are alternately arranged along the first direction, and the first pole sheet includes a bending layer, and the bending layer connects two adjacent first pole sheet layers.

10. The battery according to claim 8 or 9, wherein The electrode unit includes two electrode assemblies, and the two electrode assemblies are arranged along the first direction; Each of the electrode assemblies includes one first electrode tab group.

11. The battery according to any one of claims 8 to 10, wherein: The first pole piece is a negative pole piece.

12. The battery according to claim 11, wherein The first electrode sheet includes a negative electrode active material; The volume distribution particle size Dv50 of the negative electrode active material is ≤15 μm, and / or the specific surface area of ​​the negative electrode active material is 0.5 m 2 / g-5m 2 / g.

13. The battery according to claim 11 or 12, wherein The first electrode sheet includes a negative electrode active material, and the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, silicon oxygen or silicon carbon.

14. The battery according to any one of claims 11 to 13, wherein: The first electrode sheet comprises a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector; 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 .

15. The battery according to any one of claims 1 to 14, wherein: The electrode unit includes a plurality of second pole sheet layers, the polarity of the second pole sheet layers is opposite to the polarity of the first pole sheet layers, and the second pole sheet layers and the first pole sheet layers are stacked along a first direction; A portion of the second pole sheet layer is provided with a second pole lug to form two second pole lug groups, each of the second pole lug groups includes a plurality of stacked and connected second pole lugs, and a second pole sheet layer without a second pole lug is provided between the two second pole lug groups.

16. The battery according to claim 15, wherein The total number of the second pole sheet layers is M, the number of the second pole tabs of each second pole tab group is K3, and K3 and M satisfy: 1 / 4≤K3 / M≤7 / 16; Optionally, 5 / 16≤K3 / M≤7 / 16.

17. The battery according to claim 16, wherein: The number of the second pole sheet layers located between two of the second pole tab groups and not provided with the second pole tabs is K4, and K4 and M satisfy: 1 / 8≤K4 / M≤1 / 2; Optionally, 1 / 8≤K4 / M≤3 / 8.

18. The battery according to any one of claims 15 to 17, wherein: The first pole ear is a negative pole ear, and the second pole ear is a positive pole ear; The number of the first electrode tabs in the first electrode tab group is greater than the number of the second electrode tabs in the second electrode tab group.

19. The battery according to claim 18, wherein The first pole lug is a copper pole lug, the second pole lug is an aluminum pole lug, and the sum of the cross-sectional areas of all the second pole lugs is A1, in mm 2 The sum of the cross-sectional areas of all the first tabs is A2, in mm 2 , satisfying: A1≤2.5A2; optionally, A1≤1.5A2.

20. The battery according to any one of claims 1 to 19, wherein: The battery cell further includes an electrolyte contained in the housing, wherein the ion conductivity of the electrolyte is 9 mS / cm-16 mS / cm.

21. The battery according to any one of claims 1 to 20, wherein: The DC impedance of the battery cell is less than or equal to 0.4 milliohms.

22. The battery according to any one of claims 1 to 21, wherein: Each of the first pole sheet layers includes a pole sheet body, and a portion of the first pole sheet layers is provided with the first pole ear extending from an end of the pole sheet body along a second direction, and the second direction is perpendicular to the first direction; In the first direction, each of the pole piece bodies at least partially overlaps with the heat exchange plate.

23. The battery according to claim 22, wherein In the second direction, the size of the heat exchange plate is H1, the size of the pole piece body is H2, 0.6≤H1 / H2≤1.2; optionally, 0.8≤H1 / H2≤1.

1.

24. The battery according to claim 22 or 23, wherein In the second direction, a distance between an edge of the pole piece body close to the first pole lug and an edge of the heat exchange plate close to the first pole lug is L1, and L1≤20mm; optionally, L1≤15mm.

25. The battery according to any one of claims 22 to 24, wherein: In the second direction, the edge of the heat exchange plate close to the first pole ear exceeds the edge of the pole piece body close to the first pole ear; or In the second direction, the edge of the heat exchange plate close to the first pole lug is flush with the edge of the pole piece body close to the first pole lug.

26. The battery according to any one of claims 1 to 25, wherein: The housing comprises two first shell walls opposite to each other along the first direction, two second shell walls opposite to each other along the second direction, and two third shell walls opposite to each other along the third direction, wherein the first direction, the second direction and the third direction are perpendicular to each other; The area of ​​the first shell wall is greater than that of the second shell wall, and the area of ​​the first shell wall is greater than that of the third shell wall.

27. The battery according to any one of claims 1 to 26, wherein: A plurality of battery cells arranged in sequence are disposed between adjacent heat exchange plates, and an arrangement direction of the plurality of battery cells is perpendicular to the first direction.

28. The battery according to any one of claims 1 to 27, wherein: The average charging rate of the battery cell is x, where x≥2.

29. The battery according to claim 28, wherein x is 2, 3, 4, 5, or 6.

30. An electrical device, comprising a battery according to any one of claims 1 to 29, wherein the battery is used to provide electrical energy.

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