Battery cell, battery device, and electric device

Abstract

This application belongs to the field of battery technology, and particularly relates to a battery cell, a battery device, and an electrical device. The battery cell includes a casing and an electrode assembly. The casing contains an electrolyte. At least a portion of the electrode assembly is located inside the casing. The electrode assembly includes a first electrode, a separator, and a second electrode. The first and second electrodes have opposite polarities and are located on opposite sides of the separator along its thickness direction. At least one surface of the separator along its thickness direction is provided with a groove. The groove is a straight groove, and the length direction of the groove is not perpendicular to a first direction. The first direction is parallel to the direction of gravity of the battery cell when the electrical device is in use, so that the length direction of the groove is not parallel to the horizontal direction. The groove can guide the electrolyte accumulated at the bottom to climb upward, which can improve the climbing ability of the electrolyte, improve the wetting effect of the electrode assembly, and also help improve the cycle performance of the battery cell.

Description

Technical Field

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

[0002] Battery devices are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] A battery device typically consists of one or more individual battery cells. One charge-discharge cycle of a battery cell is called a cycle. The cycle performance of a battery cell directly affects its capacity retention, internal resistance, reliability, and ultimate lifespan. Therefore, improving the cycle performance of individual battery cells is an important research direction in the field of battery technology.

[0004] The above statements are for the purpose of providing background information in relation to this application only and do not necessarily constitute prior art. Utility Model Content

[0005] The purpose of this application is to provide a battery cell, a battery device, and an electrical device that can improve the cycle performance of the battery cell.

[0006] The technical solution adopted in the embodiments of this application is:

[0007] In a first aspect, a battery cell is provided, the battery cell including a casing and an electrode assembly, the casing containing an electrolyte; at least a portion of the electrode assembly is located inside the casing, the electrode assembly including a first electrode, a separator and a second electrode, the first electrode and the second electrode having opposite polarities, the first electrode and the second electrode being located on opposite sides of the separator along its own thickness direction; at least one surface of the separator along its own thickness direction is provided with a groove, the groove being a straight groove, the length direction of the groove being not perpendicular to a first direction, the first direction being parallel to the direction of gravity of the battery cell when the electrical device is in use.

[0008] By adopting the technical solution of this embodiment, during the charging and discharging process of the battery cell, ions pass through the separator and are inserted and extracted back and forth between the second electrode and the first electrode via the electrolyte, thereby realizing the electrical energy transmission of the battery cell. The separator has a groove on at least one surface along its thickness direction. The groove is a straight groove, and the length direction of the groove is not perpendicular to the first direction. The first direction is parallel to the direction of gravity of the battery cell when the electrical device is in use, so that the length direction of the groove is not parallel to the horizontal direction. This can guide the electrolyte accumulated at the bottom to climb upward, improve the climbing ability of the electrolyte, improve the wetting effect of the electrode assembly, reduce the ion transmission resistance, improve the distribution uniformity of the electrolyte, and improve the cycle performance of the battery cell.

[0009] In some embodiments, the angle between the length direction of the groove and the first direction ranges from 0° to 45°; optionally, the angle between the length direction of the groove and the first direction ranges from 0° to 30°.

[0010] By adopting the technical solution of this embodiment, the electrolyte accumulated at the bottom can be effectively guided to rise upwards, thereby effectively improving the uniformity of electrolyte distribution, enhancing the wetting effect, reducing ion transport resistance, and improving cycle performance.

[0011] In some embodiments, the separator includes a base film and a coating, wherein at least one surface of the base film along the thickness direction of the separator is covered with the coating; at least a portion of the groove is located in the coating, and the groove forms a first opening on the surface of the coating opposite to the base film.

[0012] By adopting the technical solution of this embodiment, it is convenient to manufacture the groove.

[0013] In some embodiments, the groove extends through the coating along the thickness direction of the separator.

[0014] By adopting the technical solution of this embodiment, the groove penetrates the coating and has a relatively deep depth, which can accommodate more electrolyte and facilitate electrolyte reflux, thereby improving the wetting effect of the electrode assembly. In addition, the groove can penetrate the coating along the thickness direction of the separator, exposing the base film. The base film can directly dissipate heat through the groove, reducing the thermal load of the separator and improving the performance of the battery cell.

[0015] In some embodiments, the groove depth is equal to the coating thickness.

[0016] By adopting the technical solution of this embodiment, the groove penetrates through the coating and terminates at the surface of the base film. The base film has good structural strength, which improves the reliability of the battery cell. Using the coating to make the groove also helps to reduce the manufacturing cost of the separator and the manufacturing cost of the battery cell.

[0017] In some embodiments, the coating includes a plurality of coating portions spaced apart, with adjacent coating portions and a base film surrounding a groove.

[0018] By adopting the technical solution of this embodiment, it is easy to form a groove.

[0019] In some embodiments, the groove does not penetrate the coating along the thickness direction of the separator.

[0020] By adopting the technical solution of this embodiment, the groove that does not penetrate the coating can provide a certain liquid storage space, and because the coating material is retained at the bottom, it can improve the overall structural integrity and mechanical strength of the coating, which is beneficial to improving the performance of the separator.

[0021] In some embodiments, the coating includes a first coating and a second coating of different materials. The first coating includes a plurality of coating portions. The second coating continuously covers the surface of the base film. The plurality of coating portions are spaced apart on the surface of the second coating facing away from the base film. Adjacent coating portions and the second coating surround each other to form a groove.

[0022] By adopting the technical solution of this embodiment, the coating adopts a two-layer structure, and the performance of the coating can be flexibly set to meet different usage requirements.

[0023] In some embodiments, the coating includes a first coating and a second coating of different materials. The first coating includes a plurality of coating portions covering the surface of the base film. The second coating includes a plurality of filling portions covering the surface of the base film. The plurality of coating portions and the plurality of filling portions are alternately distributed along a second direction, which is perpendicular to the thickness direction of the separator and the first direction. Two adjacent coating portions and the filling portion located between two adjacent coating portions together form a groove.

[0024] By adopting the technical solution of this embodiment, the first coating and the second coating form a single-layer composite structure, which is beneficial to reduce the thickness of the separator and improve the volumetric energy density of the battery cell; multiple coating parts and multiple filling parts are arranged alternately in the second direction, the overall structure is regular and convenient for coating production.

[0025] In some embodiments, the first coating is a polymer coating and the second coating is a ceramic coating.

[0026] By adopting the technical solution of this embodiment, the first coating is a polymer coating, which is beneficial to improve the adhesion between the separator and the first electrode and / or the second electrode, and reduce the risk of interlayer delamination during battery cell cycling; the second coating is a ceramic coating, which has heat resistance and insulation properties, which is beneficial to improve the high temperature resistance and insulation performance of the separator, and improve the reliability of battery cell use.

[0027] In some embodiments, the electrode assembly is a wound structure, and the separator is wound to form M separator windings, M≥30, where M is a positive integer. The M separator windings have multiple coating portions, which are spaced apart along a second direction, which is the winding direction of the electrode assembly.

[0028] By adopting the technical solution of this embodiment, the separator winding ring includes multiple coating portions, which are spaced apart along the winding direction of the electrode assembly. This facilitates the diffusion of electrolyte along the groove in the axial direction of the electrode assembly, improves the ability of electrolyte to climb and flow back along the axial direction of the electrode assembly, improves the wetting effect of the wound electrode assembly, and improves the cycle performance of the battery cell.

[0029] In some embodiments, the plurality of coating portions include a first coating portion, the innermost isolation winding is the first isolation winding, at least one of the first N isolation windings has a plurality of first coating portions, M / 3-1<N≤M / 3, where N is a positive integer; a groove is formed between two adjacent first coating portions.

[0030] By adopting the technical solution of this embodiment, the inner ring of the electrode assembly has a groove, thereby improving the electrolyte reflux efficiency of the inner ring of the electrode assembly, improving the wetting effect of the wound electrode assembly, and improving the cycle performance of the battery cell.

[0031] In some embodiments, the thickness of the first coating portion ranges from 2 μm to 6 μm; alternatively, the thickness of the first coating portion ranges from 2.5 μm to 4 μm.

[0032] By adopting the technical solution of this embodiment, both the wetting effect and volumetric energy density of the electrode assembly can be taken into account.

[0033] In some embodiments, the plurality of coating portions include second coating portions, at least one of the N+1 to Kth isolation windings has a plurality of second coating portions, 2M / 3-1<K≤2M / 3, where K is a positive integer; a groove is formed between two adjacent second coating portions.

[0034] By adopting the technical solution of this embodiment, the middle ring of the electrode assembly has a groove, thereby improving the electrolyte reflux efficiency of the middle ring of the electrode assembly, improving the wetting effect of the wound electrode assembly, and improving the cycle performance of the battery cell.

[0035] In some embodiments, the thickness of the first coating portion is greater than the thickness of the second coating portion.

[0036] By adopting the technical solution of this embodiment, the thickness of the first coating portion is greater than the thickness of the second coating portion, which helps to reduce the distance difference between the first and second electrode plates in the inner ring portion and the middle ring portion of the electrode assembly, thereby improving the wetting effect of the electrode assembly.

[0037] In some embodiments, the thickness of the second coating portion ranges from 0.5 μm to 3 μm; alternatively, the thickness of the second coating portion ranges from 0.7 μm to 2 μm.

[0038] By adopting the technical solution of this embodiment, both the wetting effect and volumetric energy density of the electrode assembly can be taken into account.

[0039] In some embodiments, the plurality of coating portions include a third coating portion, at least one of the K+1 to Mth isolation windings has a plurality of third coating portions, and a groove is formed between two adjacent third coating portions.

[0040] By adopting the technical solution of this embodiment, the outer ring of the electrode assembly has a groove, thereby improving the electrolyte reflux efficiency of the outer ring of the electrode assembly, improving the wetting effect of the wound electrode assembly, and improving the cycle performance of the battery cell.

[0041] In some embodiments, the thickness of the second coating portion is greater than the thickness of the third coating portion.

[0042] By adopting the technical solution of this embodiment, the thickness of the second coating portion is greater than the thickness of the third coating portion, which helps to reduce the distance difference between the first electrode and the second electrode in the middle ring portion and the outer ring portion of the electrode assembly, and improves the wetting effect of the electrode assembly.

[0043] In some embodiments, the thickness of the third coating portion ranges from 0.1 μm to 1.5 μm; optionally, the thickness of the third coating portion ranges from 0.2 μm to 1 μm.

[0044] By adopting the technical solution of this embodiment, the wetting effect and volumetric energy density of the electrode assembly can be better balanced.

[0045] In some embodiments, the thickness of the coating portion decreases along the second direction.

[0046] By adopting the technical solution of this embodiment, the thickness of the coating portion decreases along the second direction. The thickness of the coating portion decreases from the inside to the outside of the electrode assembly, which can reduce the distance difference between the first electrode and the second electrode from the inside to the outside of the electrode assembly, improve the distance consistency between the first electrode and the second electrode, and improve the wetting effect of the electrode assembly.

[0047] In some embodiments, a plurality of coating portions are spaced apart along a second direction, and the groove extends along a third direction. The second direction is perpendicular to the first direction and the thickness direction of the separator. The third direction is not perpendicular to the first direction and is perpendicular to the thickness direction of the separator. The second direction and the third direction intersect.

[0048] By adopting the technical solution of this embodiment, the multiple coating parts are arranged in a regular manner, which helps to reduce the difficulty of coating production.

[0049] In some embodiments, the distance between two adjacent coated portions is equal to the dimension of the coated portion along the second direction.

[0050] By adopting the technical solution of this embodiment, the coating width is equal to the spacing width, which facilitates the fabrication of the coating section.

[0051] In some embodiments, the groove extends through the coating along a first direction.

[0052] By adopting the technical solution of this embodiment, the electrolyte located at the opposite two end faces of the separator along the first direction can flow directly into the groove for reflux, which is beneficial to improve the wetting efficiency of the electrode assembly and improve the cycle performance of the battery cell.

[0053] In some embodiments, the distance between two adjacent coating portions ranges from 0.5 mm to 4 mm, and optionally, the distance between two adjacent coating portions ranges from 1 mm to 2.5 mm.

[0054] By adopting the technical solution of this embodiment, the groove has a suitable groove width, which can improve the reflux efficiency and storage capacity of the electrolyte, improve the wetting efficiency of the electrode assembly, and better separate the base film from the first electrode and / or the second electrode, so that the groove has a suitable space for electrolyte reflux and storage, thereby improving the wetting effect of the electrode assembly.

[0055] In some embodiments, the number of grooves is multiple, and the multiple grooves include at least one first groove and at least one second groove. The first groove extends along a third direction, and the second groove extends along a fourth direction. The third and fourth directions are perpendicular to the thickness direction of the spacer, intersect each other, and are not perpendicular to the first direction.

[0056] By adopting the technical solution of this embodiment, the first groove can guide the electrolyte to diffuse along a third direction, and the second groove can guide the electrolyte to diffuse along a fourth direction. Electrolyte can be replenished to the first electrode and / or the second electrode from multiple directions, which is beneficial to improving the wetting effect of the electrode assembly and improving the cycle performance of the battery cell.

[0057] In some embodiments, the coating is a ceramic coating, a polymer coating, or a polymer-ceramic coating.

[0058] By adopting the technical solution of this embodiment, grooves can be flexibly set on different types of coatings to meet different usage requirements.

[0059] In some embodiments, the spacer has grooves on both opposite sides along its thickness direction.

[0060] By adopting the technical solution of this embodiment, grooves are provided on both sides of the separator, which can better wet the first electrode and the second electrode, reduce the ion transport resistance, and help improve the cycle performance of the battery cell.

[0061] In some embodiments, along the thickness direction of the spacer, the projections of the grooves located on both sides of the spacer along its own thickness direction intersect.

[0062] By adopting the technical solution of this embodiment, the projections of the grooves on both sides of the separator along its thickness direction intersect, which is beneficial to improving the structural stability of the separator and the reliability of the battery cell. Furthermore, since the electrolyte can pass through the separator, the electrolyte in the groove opposite the first electrode can penetrate the separator and wet the first electrode, and the electrolyte in the groove opposite the second electrode can penetrate the separator and wet the second electrode. Since the projections of the grooves on both sides of the separator intersect, both the first and second electrodes on both sides of the separator receive more sufficient electrolyte wetting in the overlapping area of ​​the groove projections, improving the uniformity of electrolyte distribution and enhancing the cycle performance of the battery cell.

[0063] In some embodiments, the first electrode includes a first current collector and a first active material layer. At least a portion of at least one surface of the first current collector along its thickness direction is connected to the first active material layer. At least a portion of the first active material layer is located between the first current collector and the separator. A groove is disposed facing the first active material layer, and at least a portion of the groove is located between the first active material layer and the second electrode.

[0064] By adopting the technical solution of this embodiment, the groove can directly replenish the electrolyte required for the reaction of the first active material layer, improve the wetting effect of the first active material layer, and improve the wetting effect of the electrode assembly.

[0065] In some embodiments, the first active material layer includes a first active material portion and a second active material portion disposed along a first direction, wherein at least one end of the first active material portion is connected to the second active material portion along the first direction, and the thickness of the second active material portion is less than the thickness of the first active material portion.

[0066] By adopting the technical solution of this embodiment, the thickness of the second active material portion is less than that of the first active material portion, making the surface of the second active material portion facing away from the first current collector closer to the first current collector than the surface of the first active material portion facing away from the first current collector. On the one hand, this can reduce the rolling pressure on the edge of the first active material layer during the first electrode rolling process, reducing the risk of edge cracking of the first active material layer; on the other hand, the side of the second active material portion facing away from the first current collector can accommodate more electrolyte, thereby facilitating electrolyte reflux. Furthermore, the thickness difference between the second and first active material portions can be used to form a siphon effect, increasing the electrolyte reflux speed, improving the wetting effect of the electrode assembly, and improving the cycle performance of the battery cell.

[0067] In some embodiments, the thickness of the second active material portion decreases along the direction from the first active material portion to the second active material portion.

[0068] By adopting the technical solution of this embodiment, a flared structure can be formed on the side of the second active material portion facing away from the first current collector. The large end of the flared structure is positioned facing away from the first active material portion. The flared structure makes it easier for the electrolyte to be drawn into the space between the first active material portion and the second electrode, which is more conducive to improving the wetting effect of the electrode assembly and improving the cycle performance of the battery cell.

[0069] In some embodiments, a gap space is formed on the side of the second active material portion facing away from the first current collector, and a portion of the groove is located between the first active material portion and the separator, with the groove extending into the gap space.

[0070] By adopting the technical solution of this embodiment, the groove extends to the side of the second active material part, so that the groove can be directly connected with the gap space of the side of the second active material part, which facilitates the return of electrolyte, improves the wetting effect of the electrode assembly, and improves the cycle performance of the battery cell.

[0071] In some embodiments, the diameter of the cylindrical battery cell is greater than or equal to 40 mm.

[0072] By adopting the technical solution of this embodiment, the diameter of the cylindrical battery cell is greater than or equal to 40mm. The large-diameter cylindrical battery cell has a higher capacity, which is beneficial to improving the energy density when multiple cylindrical battery cells are assembled into a group. The groove of the separator can effectively improve the electrolyte reflux efficiency and improve the wetting performance and cycle performance of the large-diameter cylindrical battery cell.

[0073] Secondly, a battery device is provided, comprising a plurality of the aforementioned battery cells.

[0074] By adopting the technical solution of this embodiment, the cycle performance of the battery cell is good, which is beneficial to improving the performance and service life of the battery device.

[0075] Thirdly, an electrical device is provided, comprising the aforementioned battery cell or battery device, wherein the battery cell or battery device is used to store or provide electrical energy.

[0076] By adopting the technical solution of this embodiment, the battery cell has good cycle performance, the battery device has good performance and long service life, which is conducive to improving the performance and service life of the electrical device.

[0077] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0078] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0079] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0080] Figure 2 Schematic diagram of a battery device provided for some embodiments of this application;

[0081] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0082] Figure 4 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0083] Figure 5 A partial cross-sectional schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application;

[0084] Figure 6 for Figure 5 Schematic diagram of the cross section at point AA;

[0085] Figure 7 This is a schematic diagram of the structure of the isolation member in the deployed state provided in some embodiments of this application;

[0086] Figure 8 A schematic diagram of the structure of various isolation components provided in some embodiments of this application in an deployed state;

[0087] Figure 9 for Figure 7 Schematic diagram of the cross section at point BB;

[0088] Figure 10 The isolation element provided for other embodiments of this application is along Figure 7 Schematic diagram of the cross section at point BB;

[0089] Figure 11 The isolation element provided in some embodiments of this application is along Figure 7 Schematic diagram of the cross section at point BB;

[0090] Figure 12 The isolation element provided in some embodiments of this application is along Figure 7 Schematic diagram of the cross section at point BB;

[0091] Figure 13Schematic diagram of the structure of the isolation member in the deployed state provided in some embodiments of this application Figure 1 ;

[0092] Figure 14 for Figure 13 The diagram shows the structure of the isolation member in its deployed state. Figure 2 ;

[0093] Figure 15 A schematic diagram of the first electrode sheet in its unfolded state, provided in some embodiments of this application;

[0094] Figure 16 for Figure 15 A cross-sectional view of the CC section.

[0095] The following are the labeling elements in the figure:

[0096] 1. Vehicle; 2. Battery assembly; 3. Controller; 4. Motor; 5. Housing; 51. First housing; 52. Second housing; 6. Battery cell; 10. Electrode assembly; 11. Positive electrode; 111. Positive current collector; 112. Positive active material layer; 12. Negative electrode; 121. Negative current collector; 122. Negative active material layer; 13. Separator; 131. Base film; 132. Coating; 13201. Ceramic coating; 13202. Polymer coating; 1321. Groove; 13211. First opening; 13212. Bottom surface of first groove; 13213. First groove; 13214. Second groove; 1322. Coated section; 13221. First coated section; 13222. Second coated section; 3223, Third coating section; 1323, First coating; 1324, Second coating; 13241, Filling section; 133, Isolation winding ring; 14, First electrode; 1401, Gap space; 141, First current collector; 1411, First current collector body; 1412, First electrode tab; 142, First active material layer; 1422, First active material section; 1423, Second active material section; 1424, First surface; 1425, Second surface; 15, Second electrode; 151, Second current collector; 1511, Second current collector body; 1512, Second electrode tab; 152, Second active material layer; 20, Outer shell; 21, Housing; 211, End wall; 212, Side wall; 22, End cap; 30, Electrode terminal. Detailed Implementation

[0097] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0098] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include at least one of that feature.

[0099] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0100] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0101] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0102] In the description of this application, it should be understood that the terms "inner", "outer", "side", "upper", "bottom", "front", "rear", etc., indicating the orientation or positional relationship are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0103] In the description of this application, it should be noted that the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0104] It should also be noted that in the embodiments of this application, the same reference numerals are used to represent the same component or part. For the same part in the embodiments of this application, the reference numerals may only be used to mark one part or component as an example. It should be understood that the reference numerals are also applicable to other identical parts or components.

[0105] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0106] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0107] A single battery cell can be a rechargeable battery, which refers to a battery cell that can be recharged after being discharged to activate the active materials and continue to be used.

[0108] A battery device can refer to a single physical module that includes one or more battery cells to provide higher voltage and capacity.

[0109] A single battery cell typically includes an electrode assembly and a housing for containing the electrode assembly. The electrode assembly typically includes a separator and two electrodes of opposite polarity, with the separator separating the two electrodes.

[0110] Electrical devices contain battery cells, which store and supply electrical energy through charging and discharging. During the charging and discharging process, the electrolyte plays a role in transporting ions. Ions mainly move back and forth between the electrodes through the electrolyte. However, the flow and distribution of the electrolyte inside the battery cell depends on natural diffusion between the electrodes. However, this method has many limitations. Due to gravity, the electrolyte will gradually accumulate at the bottom of the electrodes, forming areas with higher local concentrations, resulting in uneven electrolyte distribution, which is not conducive to ion transport and affects the cycle performance of the battery cell.

[0111] In view of this, the present application provides a battery cell that, through the rational design of the separator structure, helps to guide the electrolyte at the bottom of the electrode upward, improves the electrolyte's climbing ability, improves the wetting effect of the electrode assembly, reduces ion transport resistance, improves the electrolyte distribution uniformity, and improves the cycle performance of the battery cell.

[0112] The battery cells described in this application are applicable to battery devices and electrical devices that use battery devices. Electrical devices can be equipment that uses battery devices as a power source or various energy storage systems that use battery devices as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0113] For ease of explanation, the following embodiments will be described using vehicle 1 as an example of an electrical device.

[0114] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0115] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0116] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0117] See Figure 2 As shown, in some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0118] A battery cell assembly may include multiple battery cells 6, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection means that multiple battery cells 6 are connected in both series and parallel.

[0119] Battery cell 6 can be a secondary battery cell, which refers to a battery cell that can be recharged after being discharged to activate the active materials and continue to be used.

[0120] As an example, the battery cell 6 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-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0121] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells 6; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells 6 into a single module. As an example, a battery module can be formed by bundling multiple battery cells 6 together with cable ties.

[0122] In some embodiments, the battery device 2 may be a battery pack, which includes a housing 5 and one or more battery cell assemblies housed within the housing 5. As an example, the battery cell assembly may be a battery module, which can be housed within the housing 5 by securing the battery module to the housing 5. Alternatively, as an example, the battery cell assembly may be housed within the housing 5 by directly securing multiple battery cells 6 to the housing 5.

[0123] In some embodiments, the housing 5 is used to house the battery cell 6, and the housing 5 can have various structures.

[0124] In some embodiments, the housing 5 may include a first housing 51 and a second housing 52. The first housing 51 and the second housing 52 are fastened together to form a closed space inside the housing 5 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing 51 may be a top cover or a bottom plate.

[0125] In some embodiments, the housing 5 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that the interior of the housing 5 forms an enclosed space to accommodate the battery cell assembly. As an example, the frame may include multiple side beams.

[0126] In some embodiments, the housing 5 may be part of the chassis structure of the vehicle 1. For example, a portion of the housing 5 may be at least a portion of the floor of the vehicle 1, or a portion of the housing 5 may be at least a portion of the crossbeams and longitudinal beams of the vehicle 1.

[0127] In some embodiments, the battery device 2 may be an energy storage device.

[0128] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0129] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0130] The following, in conjunction with the appendix Figures 3 to 16The battery cell 6 of this application will be described in detail with reference to specific embodiments. In the embodiments of this application, see [reference needed]. Figures 3-6 As shown, the axial direction of battery cell 6 can be referenced in the S direction. (See reference...) Figures 7-14 As shown, the spacer 13 is in its unfolded state. The thickness direction of the spacer 13 can be referenced to the Y direction, the length direction to the X direction, and the width direction to the Z direction. (See also...) Figure 15 and Figure 16 As shown, the first electrode 14 is in the unfolded state. The thickness direction of the first electrode 14 can be referred to the Y1 direction, the length direction of the first electrode 14 can be referred to the X1 direction, and the width direction of the first electrode 14 can be referred to the Z1 direction.

[0131] See Figures 3-6 As shown, this application embodiment provides a battery cell 6, which includes a housing 20 and an electrode assembly 10, with at least a portion of the electrode assembly 10 housed within the housing 20.

[0132] The outer shell 20 may be a hollow structure, with an internal space for accommodating the electrode assembly 10 and the electrolyte.

[0133] In some embodiments, the housing 20 may be a metal housing, such as a steel housing, an aluminum housing, a composite metal housing (e.g., a copper-aluminum composite housing), or other metal housings. Alternatively, the housing 20 may also be a non-metallic housing, such as a plastic housing (e.g., polypropylene).

[0134] In some embodiments, the housing 20 can be a sealed structure or a non-sealed structure. As an example, when the housing 20 is a non-sealed structure, it serves to protect the electrode assembly, and a sealing bag is included between the housing 20 and the electrode assembly 10 to encapsulate the electrode assembly 10 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the housing is a sealed structure, it is used to encapsulate the electrode assembly 10 and components such as the electrolyte.

[0135] As an example, the battery cell 6 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include square battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0136] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening.

[0137] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0138] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell.

[0139] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0140] 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 (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell can have higher structural strength and improve reliability.

[0141] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0142] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0143] In some embodiments, the housing 21 includes an integrally formed sidewall 212 and an endwall 211, the endwall 211 and the end cap 22 being opposite each other along the axial direction of the battery cell 6, and the end cap 22 being sealed to the sidewall 212.

[0144] Electrode assembly 10 is the component in the battery cell 6 where the electrochemical reaction takes place. Electrode assembly 10 can be entirely housed within housing 20 or partially housed within housing 20. For example, a portion of the tabs of electrode assembly 10 can extend outside housing 20.

[0145] Optionally, the electrode assembly 10 is entirely housed within the housing 20.

[0146] In some embodiments, the electrode assembly 10 includes a positive electrode 11 and a negative electrode 12. During the charging and discharging of the battery cell 6, active ions (e.g., lithium ions) are inserted and extracted back and forth between the positive electrode 11 and the negative electrode 12.

[0147] In some embodiments, the positive electrode 11 may include a positive current collector 111 and a positive active material layer 112 disposed on at least one surface of the positive current collector 111.

[0148] As an example, the positive current collector 111 has two surfaces opposite each other in its own thickness direction, and the positive active material layer 112 is disposed on either or both of the two opposite surfaces of the positive current collector 111.

[0149] As an example, the positive current collector 111 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can 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.).

[0150] As an example, the positive electrode active material layer 112 includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. 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, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0151] In some embodiments, the negative electrode sheet 12 may include a negative electrode current collector 121 and a negative electrode active material layer 122 disposed on at least one surface of the negative electrode current collector 121.

[0152] As an example, the negative electrode current collector 121 has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer 122 is disposed on either or both of the two opposite surfaces of the negative electrode current collector 121.

[0153] As an example, the negative electrode current collector 121 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material substrate 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.).

[0154] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cell 6. 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, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cell 6 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0155] In some embodiments, the positive current collector 111 may be made of aluminum, and the negative current collector 121 may be made of copper.

[0156] In some embodiments, the electrode assembly 10 further includes a separator 13 disposed between the positive electrode 11 and the negative electrode 12. The separator 13 serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0157] The separator 13 may be partially located between the positive electrode 11 and the negative electrode 12. For example, the separator 13 protrudes from both ends of the positive electrode 11 and the negative electrode 12 along the axial direction of the battery cell 6; or the entire separator 13 may be located between the positive electrode 11 and the negative electrode 12.

[0158] In some embodiments, the separator 13 is a separator membrane. The separator membrane of this application can be any known porous structure separator membrane with good chemical and mechanical stability.

[0159] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramic. The separator is a multilayer composite film. When the separator is a multilayer composite film, the materials of each layer can be the same or different. The separator 13 can be a single component located between the positive electrode 11 and the negative electrode 12, or it can be attached to the surface of the positive electrode 11 or the surface of the negative electrode 12. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0160] In some embodiments, the battery cell 6 further includes an electrolyte that serves to conduct ions between the positive electrode 11 and the negative electrode 12. The electrolyte used in this application can be selected according to requirements.

[0161] In some embodiments, the electrolyte includes an electrolyte salt and a solvent.

[0162] 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0163] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may 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, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0164] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell 6, such as additives that improve the overcharge / fast charge performance of the battery cell 6, additives that improve the high-temperature performance of the battery cell 6, additives that improve the low-temperature performance of the battery cell 6, etc.

[0165] The electrode assembly 10 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0166] In some embodiments, the positive electrode 11, the negative electrode 12, and the separator 13 are wound together.

[0167] The electrode assembly 10 has a wound structure. For example, the positive electrode 11, the separator 13, and the negative electrode 12 are wound into a cylindrical wound structure.

[0168] In some embodiments, the electrode assembly 10 has a stacked structure.

[0169] As an example, multiple positive electrode plates 11 and multiple negative electrode plates 12 can be set, and multiple positive electrode plates 11 and multiple negative electrode plates 12 can be stacked alternately.

[0170] As an example, multiple positive electrode plates 11 can be provided, and negative electrode plates 12 can be folded to form multiple stacked folded segments, with a positive electrode plate 11 sandwiched between adjacent folded segments.

[0171] As an example, both the positive electrode 11 and the negative electrode 12 are folded to form multiple stacked folded segments.

[0172] As an example, multiple separators 13 can be provided, respectively disposed between any adjacent positive electrode 11 or negative electrode 12.

[0173] As an example, the separator 13 can be continuously arranged and disposed between any adjacent positive electrode 11 or negative electrode 12 by means of folding or rolling.

[0174] In some embodiments, the electrode assembly 10 may be cylindrical, flat, or polygonal, etc.

[0175] In some embodiments, the electrode assembly 10 is provided with tabs that can conduct current from the electrode assembly 10. The tabs include a positive tab and a negative tab.

[0176] Please combine them together Figure 7 and Figure 8As shown, in some embodiments, the battery cell 6 includes a housing 20 and an electrode assembly 10. The housing 20 contains an electrolyte. At least a portion of the electrode assembly 10 is located inside the housing 20. The electrode assembly 10 includes a first electrode 14, a separator 13, and a second electrode 15. The first electrode 14 and the second electrode 15 have opposite polarities and are located on opposite sides of the separator 13 along its thickness direction. At least one surface of the separator 13 along its thickness direction is provided with a groove 1321. The groove 1321 is a straight groove, and the length direction of the groove 1321 is not perpendicular to a first direction, which is parallel to the direction of gravity of the battery cell 6 when the device is in use.

[0177] The battery cell 6 is used in the electrical device. The battery cell 6 is installed in the electrical device and serves as an energy storage unit or discharge unit of the electrical device to store or release electrical energy.

[0178] One of the first electrode 14 and the second electrode 15 is the aforementioned positive electrode 11, and the other is the aforementioned negative electrode 12.

[0179] A portion of the spacer 13 is located between the first electrode 14 and the second electrode 15. Alternatively, the entire spacer 13 is located between the first electrode 14 and the second electrode 15.

[0180] The separator 13 can refer to a component used to separate the first electrode 14 and the second electrode 15. The first electrode 14 and the second electrode 15 are located on opposite sides of the separator 13 in the thickness direction. The separator 13 serves to insulate and separate while allowing ions to pass through.

[0181] The spacer 13 has a groove 1321 on at least one surface along its own thickness direction. It can be understood that at least one of the two surfaces of the spacer 13 that are relatively distributed along its own thickness direction has a groove 1321.

[0182] In some examples, the surface of the separator 13 facing the first electrode 14 has a groove 1321.

[0183] In some examples, the surface of the separator 13 facing the second electrode 15 has a groove 1321.

[0184] In some examples, the surface of the separator 13 facing the first electrode 14 and the surface facing the second electrode 15 are provided with grooves 1321, that is, the separator 13 has grooves 1321 on both sides.

[0185] The groove 1321 can refer to the recessed structure formed on the spacer 13. The cross-sectional shape of the groove 1321 can be rectangular, arc-shaped, triangular, or other similar shapes.

[0186] When the isolation member 13 is in the unfolded state, the groove 1321 is straight in shape and is a straight groove.

[0187] The length direction of the groove 1321 is not perpendicular to the first direction. It can be understood that the length direction of the groove 1321 is parallel to or intersects the first direction at an angle.

[0188] The first direction is parallel to the direction of gravity of the battery cell 6 when the electrical device is in use. It can be understood that when the electrical device (e.g., vehicle 1) is parked on a level road, the direction of gravity of the battery cell 6 is parallel to the first direction, which is parallel to the height direction of the battery cell 6 when it is loaded with the electrical device.

[0189] In some examples, when the spacer 13 is in the unfolded state, the first direction may be parallel to the width direction of the spacer 13, and the second direction may be the length direction of the spacer 13.

[0190] After the first electrode 14, the second electrode 15 and the separator 13 are stacked, the electrode assembly 10 is wound along the second direction to form a wound structure. When the electrode assembly 10 is in the wound state, the second direction is the winding direction V of the electrode assembly 10. After the electrode assembly 10 is wound, it can form a columnar structure. The first direction is parallel to the axial direction of the electrode assembly 10.

[0191] In some examples, when the spacer 13 is in the unfolded state, the number of grooves 1321 can be one or more, and the multiple grooves 1321 can be arranged at intervals along the second direction. The surface of the spacer 13 is also provided with one or more third grooves, the third grooves are perpendicular to the first direction, and the multiple third grooves can be arranged at intervals along the first direction. The multiple grooves 1321 and the multiple third grooves are arranged in a grid.

[0192] For example, multiple grooves 1321 may be arranged at intervals along the second direction, the grooves 1321 may be set at an angle to the first direction, or the grooves 1321 may be parallel to the first direction.

[0193] By adopting the technical solution of this embodiment, during the charging and discharging process of the battery cell 6, ions pass through the separator 13 and are inserted and extracted back and forth between the second electrode 15 and the first electrode 14 via the electrolyte, thereby realizing the power transmission of the battery cell 6. The separator 13 has a groove 1321 on at least one surface along its thickness direction. The groove 1321 is a straight groove. The length direction of the groove 1321 is not perpendicular to the first direction. The first direction is parallel to the direction of gravity of the battery cell 6 when the electrical device is in use. This makes the length direction of the groove 1321 not parallel to the horizontal direction, thereby guiding the electrolyte accumulated at the bottom to climb upward, improving the climbing ability of the electrolyte, improving the wetting effect of the electrode assembly 10, reducing the ion transmission resistance, improving the distribution uniformity of the electrolyte, and improving the cycle performance of the battery cell 6.

[0194] During the charging and discharging process of the battery cell 6, the electrode assembly 10 expands, the distance between the second electrode 15 and the first electrode 14 decreases, the electrolyte between the first electrode 14 and the second electrode 15 is squeezed out, and the squeezed electrolyte can flow back through the groove 1321, providing a channel for the electrolyte to flow back, reducing the difficulty of electrolyte flow back, reducing the resistance to ion transport, improving the wetting effect of the electrode assembly 10, and also helping to improve the cycle performance of the battery cell 6.

[0195] Please refer to the following: Figures 9-14 As shown, in some embodiments, the angle between the length direction of the groove 1321 and the first direction ranges from 0° to 45°.

[0196] The angle between the length direction of the groove 1321 and the first direction is α1, where 0°≤α1≤45°. The value of α1 can be 0°, 45°, or any value between 0° and 45°. For example, the value of α1 can be 0°, 2°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°.

[0197] When α1 equals 0, the groove 1321 is vertically positioned. As the electrolyte flows along the groove 1321, the upward path is shorter, the flow resistance is lower, and the electrolyte's climbing effect is better. The closer α1 is to 0°, the closer the length direction of the groove 1321 is to vertically upward. As the electrolyte flows along the groove 1321, the upward path is straighter, and the flow resistance is lower. In this case, the electrolyte accumulated at the bottom can quickly flow to the top of the electrode assembly 10 through the groove 1321, reducing losses during the flow process. This is suitable for scenarios where it is necessary to quickly fill the electrolyte gaps in the upper part of the electrode assembly 10.

[0198] α1 is located between 0° and 45°. The groove 1321 is inclined but close to vertical. The groove 1321 can effectively guide the electrolyte to climb upward. At the same time, the groove 1321 can also guide the electrolyte to expand in the horizontal direction, which is beneficial to improving the overall wetting uniformity of the surface of the first electrode 14 and / or the second electrode 15.

[0199] By adopting the technical solution of this embodiment, the electrolyte accumulated at the bottom can be effectively guided to rise upwards, thereby effectively improving the uniformity of electrolyte distribution, enhancing the wetting effect, reducing ion transport resistance, and improving cycle performance.

[0200] In some embodiments, the angle between the length direction of the groove 1321 and the first direction is in the range of 0° to 30°.

[0201] 0°≤α1≤30°.

[0202] By adopting the technical solution of this embodiment, the electrolyte accumulated at the bottom can be guided to rise more effectively, thereby improving the uniformity of electrolyte distribution, enhancing the wetting effect, reducing ion transport resistance, and improving cycle performance.

[0203] In some embodiments, the separator 13 includes a base film 131 and a coating 132, wherein at least one surface of the base film 131 along the thickness direction of the separator 13 is covered with the coating 132; at least a portion of the groove 1321 is located on the coating 132, and the groove 1321 forms a first opening 13211 on the surface of the coating 132 facing away from the base film 131.

[0204] The separator 13 has a multi-layer structure, and the base film 131 is the main part of the separator 13. The base film 131 serves to separate the first electrode 14 and the second electrode 15. The base film 131 can also provide support for the coating 132. The base film 131 can be made of at least one of the following materials: glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The coating 132 can refer to the coating structure coated on the surface of the base film 131. The coating 132 can be the above-mentioned inorganic particle coating, organic particle coating, or organic / inorganic composite coating.

[0205] The base film 131 and the coating 132 are stacked along the thickness direction of the separator 13. At least one of the two surfaces of the base film 131 that are relatively distributed along the thickness direction of the separator 13 is covered with the coating 132. The thickness direction of the base film 131 is parallel to the thickness direction of the separator 13. At least one of the two surfaces of the base film 131 that are relatively distributed along its own thickness direction is covered with the coating 132.

[0206] In some examples, a coating 132 is provided between the base film 131 and the first electrode 14; or, a coating 132 is provided between the base film 131 and the second electrode 15; or, a coating 132 is provided between both the base film 131 and the first electrode 14 and between the base film 131 and the second electrode 15. The coating 132 may cover the entire surface of the base film 131 or a portion of the surface of the base film 131.

[0207] The coating 132 can be a single-layer structure or a multi-layer structure.

[0208] The groove 1321 refers to a recessed structure formed on the separator 13. The opening formed by the groove 132 on the surface of the coating 132 facing away from the base film 131 is the first opening 13211, and the groove surface opposite to the first opening 13211 is the first groove bottom surface 13212. The cross-sectional shape of the groove 1321 can be or resemble a rectangle, an arc, or a triangle. The first opening 13211 facilitates the entry of the electrolyte between the first electrode 14 and the second electrode 15 into the groove 1321 for storage or flow. The groove 1321 can be formed by the coating 132 through methods such as intermittent coating or laser etching.

[0209] In some examples, the cross-sectional shape of the groove 1321 may be rectangular or similar to a rectangle, and the bottom surface 13212 of the first groove may be planar or similar to a planar surface.

[0210] In some examples, the cross-sectional shape of the groove 1321 may be or similar to an arc or a triangle, and the bottom surface of the first groove 13212 may be or similar to a straight line, which is the straight line farthest from the first opening 13211.

[0211] At least a portion of the groove 1321 is located in the coating 132. It is understood that a portion of the groove 1321 is located in the coating 132 and another portion is located in the base film 131, that is, the groove 1321 penetrates at least a portion of the coating 132 and the base film 131; or, the entire groove 1321 is located in the coating 132, the groove 1321 penetrates the coating 132 but does not extend into the interior of the base film 131, that is, the groove 1321 only penetrates the coating 132; or, the groove 1321 does not penetrate the coating 132, that is, the groove 1321 exists only inside the coating 132.

[0212] By adopting the technical solution of this embodiment, it is convenient to manufacture the groove 1321.

[0213] In some embodiments, the groove 1321 penetrates the coating 132 along the thickness direction of the separator 13.

[0214] Along the thickness direction of the separator 13, the groove 1321 penetrates the coating 132, wherein the groove 1321 may partially extend to the base film 131, and the surface of the base film 131 forms a recessed structure, which is part of the groove 1321. The groove depth T of the groove 1321 is greater than the thickness t of the coating 132. The groove 1321 does not extend to the base film 131, the surface of the base film 131 is flat, and the groove depth T of the groove 1321 is equal to the thickness t of the coating 132.

[0215] By adopting the technical solution of this embodiment, the groove 1321 penetrates the coating 132. The groove 1321 has a relatively deep depth, which can accommodate more electrolyte, which is conducive to electrolyte reflux and improves the wetting effect of the electrode assembly 10. In addition, the groove 1321 can penetrate the coating 132 along the thickness direction of the separator 13, and the base film 131 is exposed. The base film 131 can be directly dissipated by the groove 1321, which reduces the thermal load of the separator 13 and improves the performance of the battery cell 6.

[0216] In some embodiments, the groove depth T of the groove 1321 is equal to the thickness t of the coating 132.

[0217] By adopting the technical solution of this embodiment, the groove 1321 penetrates through the coating 132 and terminates on the surface of the base film 131. The base film 131 has good structural strength, which is beneficial to improving the structural strength of the separator 13 and improving the reliability of the battery cell 6. Using the coating 132 to make the groove 1321 is also beneficial to reduce the manufacturing cost of the separator 13 and the manufacturing cost of the battery cell 6.

[0218] In some embodiments, the coating 132 includes a plurality of coating portions 1322, which are spaced apart, and adjacent two coating portions 1322 and the base film 131 surround to form a groove 1321.

[0219] The groove 1321 divides the coating 132 into multiple sections. The portion of the coating 132 located on the side of the groove 1321 forms a coating section 1322. Multiple coating sections 1322 are spaced apart. The sides of two adjacent coating sections 1322 facing each other and the surface of the base film 131 surround the groove 1321.

[0220] The groove 1321 is located between two adjacent coating portions 1322; the coating 132 can be applied to the base film 131 by intermittent coating, the area where the coating is applied to the base film 131 forms the coating portion 1322, and the area where the coating is not applied forms the groove 1321; for example, the coating 132 can be a zebra strip structure, each strip being a coating portion 1322.

[0221] By adopting the technical solution of this embodiment, it is easy to form the groove 1321.

[0222] In some embodiments, the groove 1321 does not penetrate the coating 132 along the thickness direction of the separator 13.

[0223] The groove depth T of the groove 1321 is less than the thickness t of the coating 132. The groove 1321 exists in the coating 132 and is recessed from the surface of the coating 132 away from the base film 131 toward the base film 131, but does not reach the contact surface between the coating 132 and the base film 131. Some coating material is still retained at the bottom.

[0224] By adopting the technical solution of this embodiment, the groove 1321 that does not penetrate the coating 132 can provide a certain liquid storage space, and because the coating material is retained at the bottom, it can improve the overall structural integrity and mechanical strength of the coating 132, which is beneficial to improving the performance of the separator 13.

[0225] In some embodiments, coating 132 includes a first coating 1323 and a second coating 1324 made of different materials. The first coating 1323 includes a plurality of coating portions 1322. The second coating 1324 continuously covers the surface of the base film 131. The plurality of coating portions 1322 are spaced apart on the surface of the second coating 1324 facing away from the base film 131. Adjacent two coating portions 1322 and the second coating 1324 surround each other to form a groove 1321.

[0226] The materials of the first coating 1323 and the second coating 1324 are different. It can be understood that the composition of the first coating 1323 and the second coating 1324 is different, or the composition of the first coating 1323 and the second coating 1324 is the same, but the content of the components is different.

[0227] In some examples, the main components in the first coating 1323 and the second coating 1324 are different, and the main component may refer to the component with the highest content in coating 132.

[0228] The coating 132 is a double-layer composite coating. The first coating 1323 and the second coating 1324 are stacked along the thickness direction of the separator 13. The layer closer to the base film 131 is the second coating 1324, and the layer farther away from the base film 131 is the first coating 1323. The second coating 1324 is located between the first coating 1323 and the base film 131. The second coating 1324 is a monolithic structure and continuously covers the surface of the base film 131. The first coating 1323 is a multi-part partitioned structure, each part forming a coating part 1322. Multiple coating parts 1322 are spaced apart and cover the surface of the second coating 1324. Grooves 1321 are formed where the second coating 1324 is not covered by coating parts 1322.

[0229] By adopting the technical solution of this embodiment, the coating 132 adopts a two-layer structure, and the performance of the coating 132 can be flexibly set to meet different usage requirements.

[0230] In some embodiments, coating 132 includes a first coating 1323 and a second coating 1324 made of different materials. The first coating 1323 includes a plurality of coating portions 1322 covering the surface of the base film 131. The second coating 1324 includes a plurality of filling portions 13241 covering the surface of the base film 131. The plurality of coating portions 1322 and the plurality of filling portions 13241 are alternately distributed along a second direction, which is perpendicular to the thickness direction and the first direction of the separator 13. Two adjacent coating portions 1322 and the filling portions 13241 located between two adjacent coating portions 1322 together form a groove 1321.

[0231] The coating 132 is a single-layer composite coating. The first coating 1323 and the second coating 1324 are both directly covered on the surface of the base film 131. Along the thickness direction of the separator 13, the first coating 1323 and the second coating 1324 have no obvious upper and lower layer relationship and belong to different areas distributed in the same plane.

[0232] The first coating 1323 includes a plurality of discrete coating portions 1322, each coating portion 1322 directly covering the surface of the base film 131; the second coating 1324 includes a plurality of discrete filling portions 13241, each filling portion 13241 also directly covering the surface of the base film 131; the plurality of coating portions 1322 and the plurality of filling portions 13241 are arranged alternately along a second direction to form a periodic distribution of coating portion 1322-filling portion 13241-coating portion 1322-filling portion 13241. A filling portion 13241 is sandwiched between two adjacent coating portions 1322, and the thickness of the coating portion 1322 is greater than the thickness of the filling portion 13241, so that two adjacent coating portions 1322 and the filling portion 13241 located between the two adjacent coating portions 1322 form a groove 1321. The opposite sides of adjacent coating portions 1322 form the two side walls 212 of the groove 1321, the surface of the filling portion 13241 forms the first groove bottom surface 13212 of the groove 1321, and the first opening 13211 of the groove 1321 is located on the side of the coating 132 facing away from the base film 131.

[0233] The second direction can refer to the thickness direction perpendicular to the spacer 13 and the first direction; for example, when the spacer 13 is in the unfolded state, the first direction is the width direction of the spacer 13, and the second direction refers to the length direction of the spacer 13.

[0234] By adopting the technical solution of this embodiment, the first coating 1323 and the second coating 1324 form a single-layer composite structure, which is beneficial to reduce the thickness of the separator 13 and improve the volumetric energy density of the battery cell 6; the multiple coating parts 1322 and the multiple filling parts 13241 are arranged alternately in the second direction, the overall structure is regular, and it is convenient to manufacture the coating 132.

[0235] In some embodiments, the first coating 1323 is a polymer coating 13202, and the second coating 1324 is a ceramic coating 13201.

[0236] Ceramic coating 13201 can refer to an inorganic ceramic material coating. Ceramic coating 13201 can be a CCS (Ceramic Coated Separator) coating. The main components of ceramic coating 13201 are ceramic materials such as alumina and boehmite, and it also includes auxiliary components such as dispersants, thickeners, binders, and wetting agents. The dispersant is generally one or more of carboxymethyl cellulose, polyacrylic acid, and their copolymers; the thickener can be carboxymethyl cellulose, xanthan gum, carrageenan, etc.; the binder is usually a heat-resistant binder such as polyimide, inorganic adhesive, or silicone; and the wetting agent is one or more of polyethers and alcohols.

[0237] Polymer coating 13202 can refer to a polymer material coating, and polymer coating 13202 can be a PCS (Polymer Coating Separator) coating.

[0238] The main components of polymer coating 13202 are polymer particles such as polyvinylidene fluoride (PVDF), and water-based thickeners such as BI-4 or CMC-Na (sodium carboxymethyl cellulose) and binders such as FA-3 (polyacrylate emulsion) are usually added.

[0239] By adopting the technical solution of this embodiment, the first coating 1323 adopts a polymer coating 13202, which is beneficial to improve the adhesion between the separator 13 and the first electrode 14 and / or the second electrode 15, and reduce the risk of interlayer delamination during battery cell 6 cycling; the second coating 1324 adopts a ceramic coating 13201, which has heat resistance and insulation properties, which is beneficial to improve the high temperature resistance and insulation performance of the separator 13, and improve the reliability of battery cell 6.

[0240] In some embodiments, the electrode assembly 10 is a wound structure, and the separator 13 is wound to form M separator windings 133, M≥30, M is a positive integer, the M separator windings 133 have a plurality of coating portions 1322, the plurality of coating portions 1322 are arranged at intervals along a second direction, the second direction being the winding direction V of the electrode assembly 10.

[0241] After the first electrode 14, the second electrode 15 and the separator 13 are stacked, the electrode assembly 10 is wound along the second direction to form a wound structure. When the electrode assembly 10 is in the wound state, the second direction is the winding direction V of the electrode assembly 10. After the electrode assembly 10 is wound, it can form a columnar structure. The first direction is parallel to the axial direction of the electrode assembly 10 and is also parallel to the winding axis of the electrode assembly 10.

[0242] In some examples, the battery cell 6 is a cylindrical battery cell, the insulating winding 133 may be circular or near-circular, and the electrode assembly 10 is a cylindrical structure or similar to a cylindrical structure, with the first direction parallel to the axial direction of the cylindrical battery cell.

[0243] In some examples, the battery cell 6 is a square battery cell, the insulating winding 133 is waist-shaped or waist-like, the two ends of the insulating winding 133 are semi-circular or semi-circular, the middle part is a straight structure or a straight structure, and the electrode assembly 10 is a flat column structure or similar to a flat column structure, with the second direction parallel to the axis of the semi-circular structure at both ends of the electrode assembly 10.

[0244] The electrode assembly 10 has a wound structure, and the insulating member 13 has an insulating winding start end C1 and an insulating winding end C2. The insulating winding start end C1 is located inside the electrode assembly 10, and the insulating winding end C2 is located outside the electrode assembly 10. Starting from the insulating winding start end C1, the insulating member 13 forms an insulating winding loop 133 every time it is wound around. It should be noted that the innermost insulating winding loop 133 is the first insulating winding loop 133, and the outermost insulating winding loop 133 is the Mth insulating winding loop 133. The Mth insulating winding loop 133 can be a full loop or less than a full loop.

[0245] Multiple coating portions 1322 are arranged at intervals along the winding direction V of the electrode assembly 10, and multiple grooves 1321 are arranged at intervals along the winding direction V of the electrode assembly 10. This facilitates the diffusion of electrolyte along the grooves 1321 in the axial direction of the electrode assembly 10, improves the ability of electrolyte to climb along the axial direction of the electrode assembly 10, and improves the cycle performance of the battery cell 6.

[0246] The number of isolation winding turns 133 is M, and the value of M is any value greater than or equal to 30; for example, the value of M can be, but is not limited to, 30, 35, 40, 45, 50, 55, and 60.

[0247] By adopting the technical solution of this embodiment, the isolation winding 133 of the separator 13 includes a plurality of coating portions 1322. The plurality of coating portions 1322 are arranged at intervals along the winding direction V of the electrode assembly 10, which is beneficial for the electrolyte to diffuse along the groove 1321 in the axial direction of the electrode assembly 10, improves the ability of the electrolyte to climb and flow back along the axial direction of the electrode assembly 10, improves the wetting effect of the wound electrode assembly 10, and improves the cycle performance of the battery cell 6.

[0248] For ease of explanation, the M insulating windings 133 are divided into three or nearly three equal parts. From the inside to the outside of the electrode assembly 10, the M insulating windings 133 are sequentially divided into a first part, a second part, and a third part. The part of the electrode assembly 10 located in the first part is called the inner ring of the electrode assembly 10, the part of the electrode assembly 10 located in the third part is called the outer ring of the electrode assembly 10, and the part of the electrode assembly 10 located in the second part is called the middle ring of the electrode assembly 10.

[0249] In some embodiments, the plurality of coating portions 1322 include a first coating portion 13221, the innermost isolation winding 133 is the first isolation winding 133, at least one of the first N isolation windings 133 has a plurality of first coating portions 13221, M / 3-1<N≤M / 3, where N is a positive integer; a groove 1321 is formed between two adjacent first coating portions 13221.

[0250] The coating portion 1322 of one or more of the isolation windings 133 located in the front N isolation windings 133 is the first coating portion 13221, and M / 3-1<N≤M / 3, where N is a positive integer, such that the first coating portion 13221 is located in the inner ring portion of the electrode assembly 10.

[0251] In some cases, after the electrode assembly 10 is wound, the distance between the first electrode 14 and the second electrode 15 increases from the inside to the outside of the electrode assembly 10, making it difficult for the electrolyte in the inner ring of the electrode assembly 10 to flow back.

[0252] By adopting the technical solution of this embodiment, the inner ring portion of the electrode assembly 10 has a groove 1321, thereby improving the electrolyte reflux efficiency of the inner ring portion of the electrode assembly 10, improving the wetting effect of the wound electrode assembly 10, and improving the cycle performance of the battery cell 6.

[0253] In some embodiments, the thickness of the first coating portion 13221 ranges from 2 μm to 6 μm.

[0254] The thickness of the first coating portion 13221 is t1, where 2μm≤t1≤6μm.

[0255] The value of t1 can be 2μm, 6μm, or any value between 2μm and 6μm. For example, the value of t1 can be 2μm, 2.2μm, 2.5μm, 3μm, 4μm, 4.5μm, 5μm, or 6μm.

[0256] The thickness of the first coating portion 13221 is set within the aforementioned range. The first coating portion 13221 can separate the base film 131 and the first electrode 14 and / or the second electrode 15, which is beneficial for increasing the distance between the first electrode 14 and the second electrode 15 in the inner ring of the electrode assembly 10, reducing the distance difference between the first electrode 14 and the second electrode 15 in the inner and outer rings of the electrode assembly 10, improving the wetting effect of the electrode assembly 10, and also facilitating the setting of a groove 1321 of a reasonable depth to improve the wetting effect of the inner ring of the electrode assembly 10. In addition, the reasonable thickness of the first coating portion 13221 is also beneficial for improving the volumetric energy density of the battery cell 6. The battery cell 6 of the present application embodiment can better balance the wetting effect and volumetric energy density of the electrode assembly 10.

[0257] In some embodiments, the thickness of the first coating portion 13221 ranges from 2.5 μm to 4 μm.

[0258] It is understandable that 2.5μm≤t1≤4μm.

[0259] By adopting the technical solution of this embodiment, the wetting effect and volumetric energy density of the electrode assembly 10 can be better balanced.

[0260] In some embodiments, the plurality of coating portions 1322 include second coating portions 13222, at least one of the N+1 to Kth isolation windings 133 has a plurality of second coating portions 13222, 2M / 3-1<K≤2M / 3, where K is a positive integer; a groove 1321 is formed between two adjacent second coating portions 13222.

[0261] The coating portion 1322 of one or more of the isolation windings 133 from the (N+1)th to the Kth is the second coating portion 13222, and 2M / 3-1<K≤2M / 3, where K is a positive integer, such that the second coating portion 13222 is located in the middle ring portion of the electrode assembly 10, and the second coating portion 13222 is located between the inner ring portion and the outer ring portion of the electrode assembly 10.

[0262] By adopting the technical solution of this embodiment, the middle ring portion of the electrode assembly 10 has a groove 1321, thereby improving the electrolyte reflux efficiency of the middle ring portion of the electrode assembly 10, improving the wetting effect of the wound electrode assembly 10, and improving the cycle performance of the battery cell 6.

[0263] In some embodiments, the thickness of the first coating portion 13221 is greater than the thickness of the second coating portion 13222.

[0264] The thickness of the second coating portion 13222 is t2, where t1 > t2.

[0265] The first coating portion 13221 can separate the base film 131 from the first electrode 14 and / or the second electrode 15 located in the inner ring portion of the electrode assembly 10, and the second coating portion 13222 can separate the base film 131 from the first electrode 14 and / or the second electrode 15 located in the middle ring portion of the electrode assembly 10.

[0266] By adopting the technical solution of this embodiment, the thickness of the first coating portion 13221 is greater than the thickness of the second coating portion 13222, which helps to reduce the distance difference between the first electrode 14 and the second electrode 15 in the inner ring portion and the middle ring portion of the electrode assembly 10, and improves the wetting effect of the electrode assembly 10.

[0267] In some embodiments, the thickness of the second coating portion 13222 ranges from 0.5 μm to 3 μm.

[0268] 0.5μm≤t2≤3μm.

[0269] The value of t2 can be 0.5μm, 3μm, or any value between 0.5μm and 3μm. For example, the value of t2 can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 1μm, 1.5μm, 2μm, 2.5μm, or 3μm.

[0270] The thickness of the second coating portion 13222 is set within the aforementioned range. The second coating portion 13222 can separate the base film 131 from the first electrode 14 and / or the second electrode 15, which helps to increase the distance between the first electrode 14 and the second electrode 15 in the middle ring of the electrode assembly 10, reduces the distance difference between the first electrode 14 and the second electrode 15 in the middle and outer rings of the electrode assembly 10, improves the wetting effect of the electrode assembly 10, and also facilitates the setting of a groove 1321 of appropriate depth to improve the wetting effect in the middle ring of the electrode assembly 10. Furthermore, the reasonable thickness of the second coating portion 13222 also helps to increase the volumetric energy density of the battery cell 6. The battery cell 6 of this embodiment can better balance the wetting effect and volumetric energy density of the electrode assembly 10.

[0271] In some embodiments, the thickness of the second coating portion 13222 ranges from 0.7 μm to 2 μm.

[0272] 0.7μm≤t2≤2μm.

[0273] By adopting the technical solution of this embodiment, the wetting effect and volumetric energy density of the electrode assembly 10 can be better balanced.

[0274] In some embodiments, the plurality of coating portions 1322 include third coating portions 13223, at least one of the K+1 to Mth isolation windings 133 has a plurality of third coating portions 13223, and a groove 1321 is formed between two adjacent third coating portions 13223.

[0275] The coating portion 1322 of one or more of the isolation windings 133 from the K+1th to the Mth is the third coating portion 13223, and the third coating portion 13223 is located in the outer ring portion of the electrode assembly 10.

[0276] By adopting the technical solution of this embodiment, the outer ring of the electrode assembly 10 has a groove 1321, thereby improving the electrolyte reflux efficiency of the outer ring of the electrode assembly 10, improving the wetting effect of the wound electrode assembly 10, and improving the cycle performance of the battery cell 6.

[0277] In some embodiments, the thickness of the second coating portion 13222 is greater than the thickness of the third coating portion 13223.

[0278] The thickness of the third coating portion 13223 is t3, where t2 > t3.

[0279] The second coating portion 13222 can separate the base film 131 from the first electrode 14 and / or the second electrode 15 located in the middle ring portion of the electrode assembly 10, and the third coating portion 13223 can separate the base film 131 from the first electrode 14 and / or the second electrode 15 located in the outer ring portion of the electrode assembly 10.

[0280] By adopting the technical solution of this embodiment, the thickness of the second coating portion 13222 is greater than the thickness of the third coating portion 13223, which helps to reduce the distance difference between the first electrode 14 and the second electrode 15 in the middle ring portion and the outer ring portion of the electrode assembly 10, and improves the wetting effect of the electrode assembly 10.

[0281] In some embodiments, the thickness of the third coating portion 13223 ranges from 0.1 μm to 1.5 μm.

[0282] 0.1μm≤t3≤1.5μm.

[0283] The value of t3 can be 0.1μm, 1.5μm, or any value between 0.1μm and 1.5μm. For example, the value of t3 can be 0.1μm, 0.15μm, 0.2μm, 0.3μm, 0.5μm, 0.8μm, 1μm, 1.2μm, or 1.5μm.

[0284] The thickness of the third coating portion 13223 is set within the aforementioned range, which facilitates the setting of grooves 1321 of appropriate depth to improve the wetting effect of the outer ring portion of the electrode assembly 10. In addition, the appropriate thickness of the third coating portion 13223 is also beneficial to improving the volumetric energy density of the battery cell 6. The battery cell 6 of the present application embodiment can better balance the wetting effect of the electrode assembly 10 and the volumetric energy density.

[0285] In some embodiments, the thickness of the third coating portion 13223 ranges from 0.2 μm to 1 μm.

[0286] 0.2μm≤t3≤1μm.

[0287] By adopting the technical solution of this embodiment, the wetting effect and volumetric energy density of the electrode assembly 10 can be better balanced.

[0288] In some embodiments, the thickness of the coating portion 1322 is progressively reduced along the second direction.

[0289] Along the winding direction V of the electrode assembly 10, the thickness of the coating portion 1322 can decrease in a stepwise manner or sequentially.

[0290] By adopting the technical solution of this embodiment, the thickness of the coating portion 1322 is progressively reduced along the second direction. The thickness of the coating portion 1322 is progressively reduced from the inside to the outside of the electrode assembly 10. This can reduce the distance difference between the first electrode 14 and the second electrode 15 from the inside to the outside of the electrode assembly 10, improve the distance consistency between the first electrode 14 and the second electrode 15, and improve the wetting effect of the electrode assembly 10.

[0291] In some embodiments, a plurality of coating portions 1322 are spaced apart along a second direction, and a groove 1321 extends along a third direction. The second direction is perpendicular to the first direction and the thickness direction of the separator 13. The third direction is not perpendicular to the first direction and is perpendicular to the thickness direction of the separator 13. The second direction and the third direction intersect.

[0292] Multiple coating portions 1322 are spaced apart along the second direction and cover the surface of the base film 131. Multiple grooves 1321 are spaced apart along the second direction. The third direction is perpendicular to the thickness direction of the separator 13. The third direction may intersect with the second direction. The third direction and the second direction do not intersect perpendicularly.

[0293] In some examples, the groove 1321 is a straight groove, the third direction is the length direction of the groove 1321, the second direction is the length direction of the spacer 13, and the third direction can be the width direction of the spacer 13. In this case, the groove 1321 extends along the width direction of the spacer 13, and the coating portion 1322 is arranged at intervals along the length direction of the spacer 13.

[0294] In some examples, the groove 1321 is a straight groove, the third direction is the length direction of the groove 1321, the second direction is the length direction of the spacer 13, and the third direction forms an angle of 30°, 45° or 60° with the length direction of the spacer 13. In this case, the groove 1321 extends obliquely, and the coating portion 1322 is arranged at intervals along the length direction of the spacer 13.

[0295] Multiple coating portions 1322 are spaced apart along a second direction and cover the surface of the base film 131, and multiple grooves 1321 are spaced apart along the second direction. For example, the coating 132 can be formed by intermittent coating.

[0296] By adopting the technical solution of this embodiment, the multiple coating parts 1322 are arranged in a regular manner, which helps to reduce the manufacturing difficulty of the coating 132.

[0297] In some embodiments, the distance between two adjacent coating portions 1322 is equal to the dimension of the coating portion 1322 along the second direction.

[0298] The distance between two adjacent coating portions 1322 is W1, where W1 can be the groove width of the groove 1321. The dimension of the coating portion 1322 along the second direction is W2, where W2 can be the width of the coating portion 1322. W1 = W2.

[0299] By adopting the technical solution of this embodiment, the coating width of the coating part 1322 is equal to the spacing width, which facilitates the manufacturing of the coating part 1322.

[0300] In some embodiments, the groove 1321 extends through the coating 132 along a first direction.

[0301] The groove 1321 penetrates the opposite two ends of the coating 132 along the first direction and forms an opening.

[0302] In some examples, the groove 1321 is parallel to and perpendicular to the first direction, penetrating the opposite end faces of the coating 132 along the first direction.

[0303] In some examples, the groove 1321 is inclined relative to the first direction, and the groove 1321 is inclined through the opposite end faces of the coating 132 along the first direction.

[0304] In some cases, after the electrode assembly 10 expands, the electrolyte is squeezed out from both ends of the electrode assembly 10, and after the electrode assembly 10 is wound, the distance between the first electrode 14 and the second electrode 15 is small, making it difficult for the electrolyte to flow back between the first electrode 14 and the second electrode 15.

[0305] By adopting the technical solution of this embodiment, the electrolyte located at the opposite end faces of the separator 13 along the first direction can flow directly into the groove 1321 for reflux, which is beneficial to improve the wetting efficiency of the electrode assembly 10 and improve the cycle performance of the battery cell 6.

[0306] In some embodiments, the distance between two adjacent coating portions 1322 ranges from 0.5 mm to 4 mm.

[0307] 0.5mm≤W1≤4mm, where the value of W1 can be 0.5mm, 4mm, or any value between 0.5mm and 4mm. For example, the value of W1 can be 0.5mm, 0.7mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, or 4mm.

[0308] By adopting the technical solution of this embodiment, the groove 1321 has a suitable groove width, which can improve the reflux efficiency and storage capacity of the electrolyte, improve the wetting efficiency of the electrode assembly 10, and also better separate the base film 131 from the first electrode 14 and / or the second electrode 15, so that the groove 1321 has a suitable space for electrolyte reflux and storage, and improve the wetting effect of the electrode assembly 10.

[0309] In some embodiments, the distance between two adjacent coating portions 1322 ranges from 1 mm to 2.5 mm.

[0310] 1mm≤W1≤2.5mm.

[0311] By adopting the technical solution of this embodiment, the wetting effect of the electrode assembly 10 can be effectively improved, and the cycle performance of the battery cell 6 can be improved.

[0312] In some embodiments, the number of grooves 1321 is multiple, and the multiple grooves 1321 include at least one first groove 13213 and at least one second groove 13214. The first groove 13213 extends along a third direction, and the second groove 13214 extends along a fourth direction. The third direction and the fourth direction are perpendicular to the thickness direction of the spacer 13, intersect each other, and are not perpendicular to the first direction.

[0313] When the spacer 13 is in the unfolded state, the first direction can refer to the width direction of the spacer 13, the third direction and the fourth direction are perpendicular to the thickness direction of the spacer 13, the third direction and the fourth direction do not intersect the first direction perpendicularly, the third direction and the fourth direction intersect, the third direction and the fourth direction intersect perpendicularly, and the third direction and the fourth direction do not intersect perpendicularly.

[0314] The surface of the spacer 13 is provided with a plurality of grooves 1321, which include two types: one type of groove 13213 and the other type of groove 13212 is a second groove 13214. The first groove 13213 extends along a third direction, and the second groove 13214 extends along a fourth direction. Both the third and fourth directions are perpendicular to the thickness direction of the spacer 13, and the third and fourth directions intersect. The first groove 13213 and the second groove 13214 can intersect and communicate with each other, forming a cross-shaped groove 1321 structure. For example, the first groove 13213 and the second groove 13214 can form a grid-like, cross-shaped, or obliquely cross-shaped structure.

[0315] By adopting the technical solution of this embodiment, the first groove 13213 can guide the electrolyte to diffuse along a third direction, and the second groove 13214 can guide the electrolyte to diffuse along a fourth direction. Electrolyte can be replenished to the first electrode 14 and / or the second electrode 15 from multiple directions, which is beneficial to improving the wetting effect of the electrode assembly 10 and improving the cycle performance of the battery cell 6.

[0316] In some embodiments, coating 132 is a ceramic coating 13201.

[0317] By adopting the technical solution of this embodiment, the ceramic coating 13201 can improve the heat resistance of the separator 13, enhance the puncture resistance of the separator 13, reduce the self-discharge of the battery cell 6 during use, thereby improving the yield of the battery cell 6.

[0318] In some embodiments, coating 132 is a polymer coating 13202.

[0319] By adopting the technical solution of this embodiment, the polymer coating 13202 can enhance the adhesion of the positive and negative electrode sheets, reduce the deformation of the battery cell 6 during the cycle, and improve the hardness of the battery cell 6. At the same time, it can also improve the wetting ability of the separator 13, enhance liquid absorption, and improve cycle life.

[0320] In some embodiments, coating 132 is a polymer ceramic coating.

[0321] Polymer ceramic coatings can be a composite coating of ceramic and polymer materials 132.

[0322] By adopting the technical solution of this embodiment, the polymer ceramic coating combines the advantages of ceramic coating 13201 and polymer coating 13202. It has the good heat resistance and puncture resistance of ceramic coating 13201, and the excellent adhesion and flexibility of polymer coating 13202. It can significantly improve the overall performance of battery cell 6, such as cycle performance and safety performance.

[0323] In some embodiments, the spacer 13 has grooves 1321 on both opposite sides along its thickness direction.

[0324] In some examples, the base film 131 has coatings 132 on both sides of the opposite side along the thickness direction of the separator 13, and the coatings 132 on both sides have grooves 1321.

[0325] By adopting the technical solution of this embodiment, grooves 1321 are provided on both sides of the separator 13, which can better wet the first electrode 14 and the second electrode 15, reduce the ion transport resistance, and help improve the cycle performance of the battery cell 6.

[0326] In some embodiments, along the thickness direction of the spacer 13, the projections of the grooves 1321 located on both sides of the spacer 13 along its own thickness direction intersect.

[0327] It is understandable that when the spacer 13 is unfolded and its projection is observed along the thickness direction of the spacer 13, the projections of the grooves 1321 facing the first pole piece 14 and the grooves 1321 facing the second pole piece 15 of the spacer 13 intersect. For example, along the thickness direction of the spacer 13, the projections of multiple grooves 1321 form a grid-like structure.

[0328] By adopting the technical solution of this embodiment, the projections of the grooves 1321 located on both sides of the separator 13 along its thickness direction intersect, which is beneficial to improving the structural stability of the separator 13 and the reliability of the battery cell 6. In addition, since the electrolyte can pass through the separator 13, the electrolyte in the groove 1321 opposite to the first electrode 14 can pass through the separator 13 to wet the first electrode 14, and the electrolyte in the groove 1321 opposite to the second electrode 15 can pass through the separator 13 to wet the second electrode 15. Since the projections of the grooves 1321 on both sides of the separator 13 intersect, the first electrode 14 and the second electrode 15 on both sides of the separator 13 receive more sufficient electrolyte wetting in the overlapping area of ​​the projections of the grooves 1321, improving the uniformity of electrolyte distribution and improving the cycle performance of the battery cell 6.

[0329] Please refer to the following: Figure 15 and Figure 16 As shown, in some embodiments, the first electrode 14 includes a first current collector 141 and a first active material layer 142. At least a portion of at least one surface of the first current collector 141 along its thickness direction is connected to the first active material layer 142. At least a portion of the first active material layer 142 is located between the first current collector 141 and the separator 13.

[0330] The first electrode 14 includes a first current collector 141 and a first active material layer 142. The first electrode 14 is a negative electrode 12, the first current collector 141 is the aforementioned negative current collector 121, and the first active material layer 142 is the aforementioned negative active material layer 122. Alternatively, the first electrode 14 is a positive electrode 11, the first current collector 141 is the aforementioned positive current collector 111, and the first active material layer 142 is the aforementioned positive active material layer 112.

[0331] The first current collector 141 has a first active material layer 142 covering one surface along its thickness direction, or both surfaces of the first current collector 141 along its thickness direction are covered with the first active material layer 142.

[0332] The first active material layer 142 may cover a portion of the surface of the first current collector 141, or it may cover the entire surface of the first current collector 141.

[0333] The first active material layer 142 can be directly applied to the first current collector 141. Alternatively, other layer structures, such as a conductive protective layer, can be provided between the first active material layer 142 and the first current collector 141. The conductive protective layer can be made by mixing a conductive agent and a binder. The binder bonds the first active material layer 142 and the first current collector 141, while the conductive agent is responsible for conducting electrons. The conductive agent can be carbon black, graphite, etc., and the binder can be polyvinylidene fluoride, etc.

[0334] The isolation member 13 has a groove 1321 on the side facing the first active material layer 142. The first opening 13211 of the groove 1321 is formed on the surface of the isolation member 13 facing the first active material layer 142. At least a portion of the groove 1321 is directly opposite the first active material layer 142, so that the groove 1321 can directly replenish the electrolyte required for the reaction of the first active material layer 142.

[0335] By adopting the technical solution of this embodiment, the groove 1321 can directly replenish the electrolyte required for the reaction of the first active material layer 142, improve the wetting effect of the first active material layer 142, and improve the wetting effect of the electrode assembly 10.

[0336] In some embodiments, the second electrode 15 includes a second current collector 151 and a second active material layer 152. At least a portion of at least one surface of the second current collector 151 along its thickness direction is connected to the second active material layer 152. At least a portion of the second active material layer 152 is located between the second current collector 151 and the separator 13.

[0337] In some examples, the second electrode 15 includes a second current collector 151 and a second active material layer 152. The second electrode 15 is a negative electrode 12, the second current collector 151 is the aforementioned negative current collector 121, and the second active material layer 152 is the aforementioned negative active material layer 122. Alternatively, the second electrode 15 is a positive electrode 11, the second current collector 151 is the aforementioned positive current collector 111, and the second active material layer 152 is the aforementioned positive active material layer 112.

[0338] The second current collector 151 has a second active material layer 152 covering one surface along its thickness direction, or both surfaces of the second current collector 151 along its thickness direction are covered with the second active material layer 152.

[0339] The second active material layer 152 may cover a portion of the surface of the second current collector 151, or it may cover the entire surface of the second current collector 151.

[0340] The second active material layer 152 can be directly covered on the second current collector 151, or other layer structures, such as a conductive protective layer, can be provided between the second active material layer 152 and the second current collector 151.

[0341] In some embodiments, the first active material layer 142 includes a first active material portion 1422 and a second active material portion 1423 disposed along a first direction. At least one end of the first active material portion 1422 along the first direction is connected to the second active material portion 1423, and the thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422.

[0342] The first active material portion 1422 is connected to the second active material portion 1423 at one end along the first direction, or the first active material portion 1422 is connected to the second active material portion 1423 at both ends along the first direction.

[0343] The thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422. The boundary between the first active material portion 1422 and the second active material portion 1423 can be referenced to the thickness transition position of the first active material layer 142. The second active material portion 1423 can become a thinning region of the first active material layer 142. The thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422, so that a larger space can be formed on the side of the second active material portion 1423, which is the gap space 1401.

[0344] In some examples, the second active material portion 1423 and the first active material portion 1422 may both have a generally equal thickness structure, with the thickness of the second active material portion 1423 being less than the thickness of the first active material portion 1422, so that the second active material portion 1423 and the first active material portion 1422 form a stepped structure.

[0345] In some examples, the first active material portion 1422 may have a generally uniform thickness. Along the direction from the first active material portion 1422 to the second active material portion 1423, the thickness of the second active material portion 1423 decreases from that of the first active material portion 1422, such that the thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422. See also [reference needed] for the direction from the first active material portion 1422 to the second active material portion 1423. Figure 16 The direction indicated by the middle arrow Z1.

[0346] By adopting the technical solution of this embodiment, the thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422, making the surface of the second active material portion 1423 facing away from the first current collector 141 closer to the first current collector 141 than the surface of the first active material portion 1422 facing away from the first current collector 141. On the one hand, this can reduce the rolling pressure on the edge of the first active material layer 142 during the rolling process of the first electrode 14, reducing the risk of edge cracking of the first active material layer 142. On the other hand, the side of the second active material portion 1423 facing away from the first current collector 141 can accommodate more electrolyte, thereby facilitating the return of electrolyte. Furthermore, the thickness difference between the second active material portion 1423 and the first active material portion 1422 can be used to form a siphon effect, increasing the speed of electrolyte return, improving the wetting effect of the electrode assembly 10, and improving the cycle performance of the battery cell 6.

[0347] In some embodiments, the thickness of the second active material portion 1423 is progressively reduced along the direction from the first active material portion 1422 to the second active material portion 1423.

[0348] For example, along the direction from the first active material portion 1422 to the second active material portion 1423, the thickness of the second active material portion 1423 decreases in a stepped manner, making the second active material portion 1423 a stepped structure; or, along the direction from the first active material portion 1422 to the second active material portion 1423, the thickness of the second active material portion 1423 decreases slowly, and the shape of the second active material portion 1423 is more rounded or smooth, which helps to reduce stress concentration and improve the structural strength of the positive electrode 11.

[0349] In some examples, along the direction from the first active material portion 1422 to the second active material portion 1423, the end face of the second active material layer 152 extends beyond the end face of the second active material portion 1423 that is close to the end face of the first active material portion 1422, and the thickness of the second active material portion 1423 decreases, so that a flared structure can be formed between the second active material portion 1423 and the second active material layer 152. The larger end of the flared structure faces away from the first active material portion 1422. The flared structure makes it easier for the electrolyte to be drawn into the space between the first active material portion 1422 and the second electrode 15, which is more conducive to improving the wetting effect of the electrode assembly 10 and improving the cycle performance of the battery cell 6. The space formed by the flared structure is the gap space 1401.

[0350] In some examples, along the direction from the first active material portion 1422 to the second active material portion 1423, the end face of the second active material layer 152 does not exceed the end face of the second active material portion 1423 that is close to the first active material portion 1422. The second active material portions 1423 of the two adjacent winding loops formed by the first electrode 14 are also arranged to form a flared structure. The large end of the flared structure is set away from the first active material portion 1422. The setting of the flared structure makes it easier for the electrolyte to be drawn into the space between the first active material portion 1422 and the second electrode 15, which is more conducive to improving the wetting effect of the electrode assembly 10 and improving the cycle performance of the battery cell 6.

[0351] In some embodiments, the first active material portion 1422 has a first surface 1424 facing away from the first current collector 141, and the second active material portion 1423 has a second surface 1425 facing away from the first current collector 141, wherein the second surface 1425 is closer to the first current collector 141 than the first surface 1424.

[0352] The distance between the second surface 1425 and the first current collector 141 is less than the distance between the first surface 1424 and the first current collector 141.

[0353] By adopting the technical solution of this embodiment, the side of the second surface 1425 facing away from the first current collector 141 has more space to accommodate the electrolyte. Furthermore, the distance difference between the second surface 1425 and the first surface 1424 and the first current collector 141 can be used to form a siphon effect, thereby increasing the speed of electrolyte reflux, improving the wetting effect of the electrode assembly 10, and improving the cycle performance of the battery cell 6.

[0354] In some embodiments, a gap space 1401 is formed on the side of the second active material portion 1423 facing away from the first current collector 141, and a portion of the groove 1321 is located between the first active material portion 1422 and the separator 13, with the groove 1321 extending into the gap space 1401.

[0355] A portion of the groove 1321 is positioned opposite to the first active material portion 1422, and a portion of the groove 1321 is positioned opposite to the second active material portion 1423. The groove 1321 is connected to the gap space 1401, allowing the electrolyte in the gap space 1401 to flow through the groove 1321 to the first active material portion 1422, thereby improving the electrolyte reflux capability.

[0356] By adopting the technical solution of this embodiment, the groove 1321 extends to the side of the second active material part 1423, so that the groove 1321 can be directly connected to the gap space 1401 on the side of the second active material part 1423, which facilitates the return of electrolyte, improves the wetting effect of the electrode assembly 10, and improves the cycle performance of the battery cell 6.

[0357] In some embodiments, the first current collector 141 includes a first current collector body 1411 and a first electrode 1412 arranged and connected along a first direction. At least a portion of the first current collector body 1411 is covered with a first active material layer 142, while the first electrode 1412 is not covered with the first active material layer 142.

[0358] Along the first direction, the first current collector 141 is divided into two parts. The part covered by the first active material layer 142 is called the first current collector body 1411, and the other part not covered by the first active material layer 142 is called the first tab 1412. The interface between the first tab 1412 and the first current collector body 1411 is based on the end face of the first active material layer 142. The first tab 1412 is used for electrical connection with the output electrode to facilitate the input and output of electrical energy.

[0359] In some examples, the first current collector 1411 may be completely covered by the first active material layer 142 or partially covered by the first active material layer 142. For example, the side of the first current collector 1411 facing away from the first tab 1412 is not covered by the first active material layer 142.

[0360] By adopting the technical solution of this embodiment, the first electrode 1412 is led out from the end of the first electrode 14 along the first direction, which facilitates the electrical connection of the first electrode 1412 with other components.

[0361] In some embodiments, the second current collector 151 includes a second current collector body 1511 and a second tab 1512 arranged and connected along a first direction. At least a portion of the second current collector body 1511 is covered with a second active material layer 152, while the second tab 1512 is not covered with the second active material layer 152.

[0362] Along the first direction, the second current collector 151 is divided into two parts. The part covered by the second active material layer 152 is called the second current collector body 1511, and the other part not covered by the second active material layer 152 is called the second tab 1512. The interface between the second tab 1512 and the second current collector body 1511 is referenced to the end face of the second active material layer 152 near the second tab 1512. The second tab 1512 is used for electrical connection with the output electrode to facilitate the input and output of electrical energy.

[0363] In some examples, the second current collector 1511 may be completely covered by the second active material layer 152 or partially covered by the second active material layer 152. For example, the side of the second current collector 1511 facing away from the second tab 1512 is not covered by the second active material layer 152.

[0364] By adopting the technical solution of this embodiment, the second tab 1512 is led out from the end of the second electrode 15 along the first direction, which facilitates the input or output of the battery cell 6.

[0365] In some embodiments, the battery cell 6 is a cylindrical battery cell with a diameter D greater than or equal to 40 mm.

[0366] The diameter D of a cylindrical battery cell can be any value greater than or equal to 40 mm. For example, the diameter D of a cylindrical battery cell can be 40 mm, 45 mm, 50 mm, or 60 mm.

[0367] Large-diameter cylindrical battery cells have higher capacity, which is beneficial for increasing energy density when multiple cylindrical battery cells are assembled into a group. In large-diameter cylindrical battery cells, the first electrode 14 and the second electrode 15 are wound with more turns, and the distance between the first electrode 14 and the second electrode 15 is smaller, which increases the difficulty of electrolyte reflux. The separator 13 is provided with grooves 1321, which can effectively improve the electrolyte reflux efficiency and improve the wetting performance and cycle performance of large-diameter cylindrical battery cells.

[0368] In some embodiments, a battery device 2 is provided, including a plurality of the aforementioned battery cells 6. The battery device 2 is used to be mounted on an electrical device, and in the use state of the electrical device, the gravity direction of the battery device 2 is parallel to the first direction.

[0369] The battery device 2 is used to be installed in the electrical device. The battery device 2 serves as an energy storage unit or a discharge unit of the electrical device to store or release electrical energy.

[0370] When the electrical device is in use, the direction of gravity of the battery device 2 is parallel to the first direction. It can be understood that when the electrical device (e.g., vehicle 1) is parked on a level road, the direction of gravity of the battery device 2 is parallel to the first direction, which is parallel to the height direction of the battery device 2 when it is mounted on the electrical device.

[0371] By adopting the technical solution of this embodiment, the cycle performance of the battery cell 6 is good, which is beneficial to improving the performance and service life of the battery device 2.

[0372] In some embodiments, an electrical device is provided, including the battery cell 6 or the battery device 2 described above, wherein the battery cell 6 or the battery device 2 is used to store or provide electrical energy.

[0373] By adopting the technical solution of this embodiment, the battery cell 6 has good cycle performance, and the battery device 2 has good performance and long service life, which is conducive to improving the performance and service life of the electrical device.

[0374] See Figures 3-9 As shown, this application provides a battery cell 6, which includes a housing 20, an electrode assembly 10, and electrode terminals 30.

[0375] The outer casing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed side wall 212 and an end wall 211. The end wall 211 and the end cap 22 are opposite each other along the axial direction of the battery cell 6. The end cap 22 is welded to the side wall 212.

[0376] Electrode terminals 30 are insulatedly disposed on end wall 211.

[0377] At least a portion of the electrode assembly 10 is housed within the housing 20. The electrode assembly 10 includes a first electrode 14, a second electrode 15, and a spacer 13, which are wound together. The spacer 13 is used to isolate the second electrode 15 and the first electrode 14.

[0378] The first electrode 14 includes a first current collector 141 and a first active material layer 142 covering the surface of the first current collector 141. The second electrode 15 includes a second current collector 151 and a second active material layer 152 covering the surface of the second current collector 151. The portion of the first current collector 141 not covered by the first active material layer 142 forms a first tab 1412, and the portion of the second current collector 151 not covered by the second active material layer 152 forms a second tab 1512. The first tab 1412 is electrically connected to the sidewall 212, and the electrode terminal 30 is electrically connected to the second tab 1512.

[0379] The separator 13 has a groove 1321 on at least one surface along its thickness direction. The groove 1321 is a straight groove, and the length direction of the groove 1321 is not perpendicular to a first direction, which is parallel to the direction of gravity of the battery cell 6 when the electrical device is in use. The angle between the length direction of the groove 1321 and the first direction is in the range of 0° to 45°.

[0380] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

Claims

1. A battery cell for use in an electrical device, characterized by, The battery cell includes: The outer casing contains the electrolyte; An electrode assembly, at least partially located within the housing, includes a first electrode, an isolator, and a second electrode. The first and second electrodes have opposite polarities and are located on opposite sides of the isolator along its thickness direction. The separator has a groove on at least one surface along its thickness direction. The groove is a straight groove. The length direction of the groove is not perpendicular to a first direction, which is parallel to the direction of gravity of the battery cell when the electrical device is in use.

2. The battery cell of claim 1, wherein: The angle between the length direction of the groove and the first direction is in the range of 0° to 45°; optionally, the angle between the length direction of the groove and the first direction is in the range of 0° to 30°.

3. The battery cell of claim 1, wherein: The separator includes a base film and a coating, wherein at least one surface of the base film along the thickness direction of the separator is covered with the coating; at least a portion of the groove is located on the coating, and the groove forms a first opening on the surface of the coating opposite to the base film.

4. The battery cell of claim 3, wherein: The groove extends through the coating along the thickness direction of the separator.

5. The battery cell of claim 4, wherein: The depth of the groove is equal to the thickness of the coating.

6. The battery cell of claim 4, wherein: The coating includes multiple coating portions, which are spaced apart, and adjacent coating portions and the base film surround to form the groove.

7. The battery cell of claim 3, wherein: Along the thickness direction of the separator, the groove does not penetrate the coating.

8. The battery cell according to claim 7, characterized in that: The coating includes a first coating and a second coating made of different materials. The first coating includes a plurality of coating portions. The second coating continuously covers the surface of the base film. The plurality of coating portions are spaced apart on the surface of the second coating facing away from the base film. Two adjacent coating portions and the second coating surround to form the groove.

9. The battery cell of claim 7, wherein: The coating includes a first coating and a second coating made of different materials. The first coating includes a plurality of coating portions covering the surface of the base film. The second coating includes a plurality of filling portions covering the surface of the base film. The plurality of coating portions and the plurality of filling portions are alternately distributed along a second direction, which is perpendicular to the thickness direction of the separator and the first direction. Two adjacent coating portions and the filling portions located between two adjacent coating portions together form the groove.

10. The battery cell according to claim 8, characterized in that: The first coating is a polymer coating, and the second coating is a ceramic coating.

11. The battery cell according to any one of claims 6, 8 to 10, characterized in that: The electrode assembly is a wound structure, and the insulating member is wound to form M insulating winding loops, M≥30, where M is a positive integer. The M insulating winding loops have multiple coating portions, and the multiple coating portions are arranged at intervals along a second direction, which is the winding direction of the electrode assembly.

12. The battery cell of claim 11, wherein: The plurality of coating portions include a first coating portion, the innermost insulating winding is the first insulating winding, at least one of the first N insulating windings has a plurality of the first coating portions, M / 3-1<N≤M / 3, where N is a positive integer; the groove is formed between two adjacent first coating portions.

13. The battery cell of claim 12, wherein: The thickness of the first coating portion ranges from 2 μm to 6 μm; optionally, the thickness of the first coating portion ranges from 2.5 μm to 4 μm.

14. The battery cell of claim 12, wherein: The plurality of coating portions include a second coating portion, at least one of the N+1 to Kth isolation windings has a plurality of second coating portions, 2M / 3-1<K≤2M / 3, where K is a positive integer; the groove is formed between two adjacent second coating portions.

15. The battery cell of claim 14, wherein: The thickness of the first coating portion is greater than the thickness of the second coating portion.

16. The battery cell of claim 14, wherein: The thickness of the second coating portion ranges from 0.5 μm to 3 μm; optionally, the thickness of the second coating portion ranges from 0.7 μm to 2 μm.

17. The battery cell of claim 14, wherein: The plurality of coating portions include a third coating portion, at least one of the K+1 to Mth isolation windings having a plurality of the third coating portions, and the groove is formed between two adjacent third coating portions.

18. The battery cell of claim 17, wherein: The thickness of the second coating portion is greater than the thickness of the third coating portion.

19. The battery cell of claim 18, wherein: The thickness of the third coating portion ranges from 0.1 μm to 1.5 μm; optionally, the thickness of the third coating portion ranges from 0.2 μm to 1 μm.

20. The battery cell of claim 11, wherein: Along the second direction, the thickness of the coating portion is progressively reduced.

21. The battery cell of any one of claims 6, 8-10, wherein: The plurality of coating portions are spaced apart along a second direction, the groove extends along a third direction, the second direction is perpendicular to the first direction and the thickness direction of the separator, the third direction is not perpendicular to the first direction, the third direction is perpendicular to the thickness direction of the separator, and the second direction and the third direction intersect.

22. The battery cell of claim 21, wherein: The distance between two adjacent coating portions is equal to the dimension of the coating portion along the second direction.

23. The battery cell of claim 21, wherein: Along the first direction, the groove penetrates the coating.

24. The battery cell of any one of claims 6, 8-10, wherein: The distance between two adjacent coating portions ranges from 0.5 mm to 4 mm, and optionally, the distance between two adjacent coating portions ranges from 1 mm to 2.5 mm.

25. The battery cell of any one of claims 1-10, wherein: The number of grooves is multiple, including at least one first groove and at least one second groove. The first groove extends along a third direction, and the second groove extends along a fourth direction. The third and fourth directions are perpendicular to the thickness direction of the separator, intersect each other, and are not perpendicular to the first direction.

26. The battery cell of any one of claims 3-7, wherein: The coating is a ceramic coating, a polymer coating, or a polymer-ceramic coating.

27. The battery cell of any one of claims 1-10, wherein: The spacer has grooves on both sides along its thickness direction.

28. The battery cell of claim 26, wherein: Along the thickness direction of the separator, the projections of the grooves located on both sides of the separator along its own thickness direction intersect.

29. The battery cell of any one of claims 1-10, wherein: The first electrode includes a first current collector and a first active material layer. At least a portion of at least one surface of the first current collector along its thickness direction is connected to the first active material layer. At least a portion of the first active material layer is located between the first current collector and the separator. The groove is disposed facing the first active material layer, and at least a portion of the groove is located between the first active material layer and the second electrode.

30. The battery cell of claim 29, wherein: The first active material layer includes a first active material portion and a second active material portion disposed along a first direction. At least one end of the first active material portion along the first direction is connected to the second active material portion, and the thickness of the second active material portion is less than the thickness of the first active material portion.

31. The battery cell of claim 30, wherein: The thickness of the second active material portion decreases along the direction from the first active material portion to the second active material portion.

32. The battery cell of claim 30, wherein: The second active material portion has a gap space formed on the side facing away from the first current collector, and the groove portion is located between the first active material portion and the separator, the groove extending into the gap space.

33. The battery cell of any one of claims 1-10, wherein: The battery cell is a cylindrical battery cell with a diameter greater than or equal to 40 mm.

34. A battery device, characterized by: The battery device comprises multiple battery cells according to any one of claims 1 to 33, and is used to be mounted on the electrical device, wherein, in the operating state of the electrical device, the direction of gravity of the battery device is parallel to the first direction.

35. An electrical device, characterized in that: Includes a battery cell according to any one of claims 1 to 33 or a battery device according to claim 34, wherein the battery cell or the battery device is used to store or provide electrical energy.

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