Current collector and battery cell, battery device and power-consuming device

Abstract

This application belongs to the field of battery technology and specifically discloses a current collector, a battery cell, a battery device, and an electrical device. The current collector comprises an insulating base layer, which includes a first main region and an edge region located outside the first main region. The porosity of the first main region of the insulating base layer is lower than that of the edge region of the insulating base layer. The design proposed in this application improves the cycle life of the battery by enhancing the wettability of the electrode by the electrolyte.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a current collector and a battery cell, a battery device, and an electrical device. Background Art

[0002] With the development of new energy technologies, batteries are being used in more and more applications, such as in mobile phones, laptops, electric vehicles, electric cars, energy storage devices, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. This places increasingly higher demands on battery performance. Summary of the Invention

[0003] The present application provides a current collector, a battery cell, a battery device, and an electrical device. The battery cell improves the wettability of the electrode by the electrolyte to improve the cycle life of the battery.

[0004] In a first aspect, the present application provides a battery cell, the battery cell comprising a current collector and an active material layer located on at least one side of the current collector;

[0005] The current collector includes an insulating base layer, the insulating base layer includes a first main region and an edge region located outside the first main region; the porosity of the first main region of the insulating base layer is smaller than the porosity of the edge region of the insulating base layer;

[0006] The current collector further comprises a conductive layer, wherein the conductive layer is located between the insulating base layer and the active material layer;

[0007] The conductive layer includes a second main region and an edge region located outside the second main region; the edge region of the conductive layer is provided with a through hole;

[0008] An orthographic projection of an edge region of the conductive layer on the insulating base layer at least partially overlaps with an edge region of the insulating base layer.

[0009] The current collector of the present application is immersed in the electrolyte in the battery cell. Since the edge area of ​​the insulating base layer of the current collector has a relatively higher probability of contact with the electrolyte than the main area, the porosity of the edge area of ​​the insulating base layer is selected in the present application to be larger than the porosity of the first main area of ​​the insulating base layer, thereby facilitating the electrolyte to fully and effectively infiltrate the edge area of ​​the insulating base layer of the current collector. The electrolyte flows from the edge area of ​​the insulating base layer to the edge area of ​​the conductive layer, and further flows to the active material layer, so that the edge position of the active material layer is fully and effectively infiltrated by the electrolyte, alleviating a series of problems such as severe polarization and increased impedance caused by the obstruction of the metal ion transmission path at the edge position of the active material layer. Therefore, the design method provided by the present application improves the cycle life of the battery by improving the uniformity of the current distribution of the battery during the charging and discharging process.

[0010] In some embodiments, the porosity of the first main region of the insulating base layer is 0 to 20%;

[0011] and / or;

[0012] The porosity of the edge area of ​​the insulating base layer is 10% to 40%.

[0013] In these embodiments, the present application discloses a specific numerical range of the porosity of the main region and edge region of the insulating base layer. Within this numerical range, the electrolyte can easily infiltrate the edge of the current collector and further infiltrate the active material layer.

[0014] In some embodiments, the first main region of the insulating base layer comprises a porous structure, and the average pore size of the porous structure is 10 nm to 10 μm;

[0015] and / or;

[0016] The edge region of the insulating base layer comprises a porous structure, and the average pore diameter of the porous structure is 10 nm to 10 μm.

[0017] In some embodiments, the insulating base layer includes a first edge region and a second edge region, the first edge region and the second edge region extend along the first direction and are arranged in the second direction, and the first main region is provided between the first edge region and the second edge region;

[0018] The first direction intersects the second direction;

[0019] The first main body region comprises a porous structure, and the average pore size of the porous structure is 50 nm to 2 μm;

[0020] and / or;

[0021] The first edge region and the second edge region comprise porous structures, and the average pore size of the porous structure of the first edge region and the average pore size of the porous structure of the second edge region are independently selected from 500 nm to 4 μm.

[0022] In some embodiments, along the second direction, the first edge region includes a surface A and a surface B that are oppositely disposed, and a distance between the surface A and the surface B is W1;

[0023] Along the second direction, the first main body region includes a C surface and a D surface that are opposite to each other, and a distance between the C surface and the D surface is W2;

[0024] Along the second direction, the second edge region includes an A' surface and a B' surface that are opposite to each other, and a distance between the A' surface and the B' surface is W3;

[0025] Satisfies: W2:W1:W3=6~8:1~2:1~2.

[0026] In some embodiments, a through hole is provided in the edge region of the conductive layer, and no hole is provided in the second main region of the conductive layer.

[0027] In some embodiments, the through holes in the edge region of the conductive layer have an average pore diameter of 100 nm to 10 μm.

[0028] In some embodiments, the conductive layer includes a third edge region and a fourth edge region, the third edge region and the fourth edge region extend along the first direction and are arranged in the second direction, and the second main region is disposed between the third edge region and the fourth edge region;

[0029] The first direction intersects the second direction;

[0030] The second main body region of the conductive layer is not provided with a hole;

[0031] The third edge region and the fourth edge region of the conductive layer are provided with through holes, and the average pore diameter of the through holes in the third edge region and the average pore diameter of the through holes in the fourth edge region are independently selected from 200 nm to 5 μm.

[0032] In some embodiments, along the second direction, the third edge region includes an E surface and an F surface that are opposite to each other, and a distance between the E surface and the F surface is T1;

[0033] Along the second direction, the second main body region includes a G surface and an H surface that are opposite to each other, and a distance between the G surface and the H surface is T2;

[0034] Along the second direction, the fourth edge region includes an E' surface and an F' surface that are opposite to each other, and a distance between the E' surface and the F' surface is T3;

[0035] Satisfies: T2:T1:T3=6~8:1~2:1~2.

[0036] In some embodiments, the material of the insulating base layer includes any one or more of polyethylene terephthalate, polyethylene, polypropylene, epoxy resin, polyamide, polyimide, polyester, polyolefin, polyacetylene, siloxane polymer, polyether, polyol, polysulfone, polysaccharide polymer, amino acid polymer, polysulfur nitride polymer, and aromatic polymer;

[0037] and / or;

[0038] The conductive layer includes metal, and the metal includes any one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, iron alloy, titanium, titanium alloy, silver and silver alloy.

[0039] In some embodiments, the insulating base layer and the conductive layer extend along a first direction and are stacked in a third direction;

[0040] The first direction intersects the third direction;

[0041] Along the third direction, the thickness of the insulating base layer is 25 μm to 50 μm;

[0042] and / or;

[0043] Along the third direction, the conductive layer has a thickness of 3 μm to 10 μm.

[0044] In some embodiments, the current collector and the active material layer extend along a first direction and are stacked in a third direction;

[0045] The first direction intersects the third direction;

[0046] Along the third direction, the active material layer includes an M surface and an N surface disposed opposite to each other, the M surface is disposed close to the current collector, and a distance H is between the M surface and the N surface;

[0047] The area extending from the M surface to the position 0.1×H is recorded as the first area, and the area extending from the N surface to the position 0.1×T1 is recorded as the second area;

[0048] The first region includes a first active material, and the second region includes a second active material;

[0049] The median particle size of the first active material is smaller than the median particle size of the second active material.

[0050] In this design, the particle size of the active material particles in the first region close to the current collector is small, and the particle size of the active material particles in the second region away from the current collector is large. Compared with the pores formed between small particles, the pores between large particles are large, and the tortuosity of the path connecting the large pores is also small. Under the same compaction density, the electrolyte will preferentially infiltrate between the electrode layers along the path with larger pore size and smaller tortuosity during the infiltration process. Therefore, the design provided in the present application accelerates the infiltration between the electrolyte and the active material particles in the second region away from the current collector, and further accelerates the infiltration of the electrolyte into the active material in the first region. As mentioned above, the current collector of the present application is immersed in the electrolyte, and the electrolyte flows from the edge area of ​​the insulating base layer to the edge area of ​​the conductive layer, and further flows to the active material layer, so the electrolyte fully and effectively infiltrates different intervals of the entire active material layer.

[0051] In some embodiments, the current collector and the active material layer extend along a first direction and are stacked in a third direction;

[0052] The first direction intersects the third direction;

[0053] Along the third direction, the active material layer includes a first active material layer disposed close to the current collector and a second active material layer located on a surface of the first active material layer away from the current collector;

[0054] The first active material layer includes a first active material, and the second active material layer includes a second active material;

[0055] The median particle size of the first active material is smaller than the median particle size of the second active material.

[0056] In some embodiments, the current collector and the active material layer extend along a first direction and are stacked in a third direction; the first direction intersects the third direction;

[0057] The active material layer includes an active material main body region and an edge thinning region located outside the active material main body region;

[0058] The orthographic projection of the edge thinning region on the current collector at least partially overlaps with the edge region of the conductive layer.

[0059] In some embodiments, the battery cell includes a separator, and the separator includes a third main body region and an edge region located outside the third main body region;

[0060] The orthographic projection of the edge region of the isolating member on the conductive layer at least partially overlaps with the edge region of the conductive layer;

[0061] The porosity of the edge area of ​​the above-mentioned separator is 70% to 80%.

[0062] A second aspect of the present application is to provide a current collector comprising an insulating base layer;

[0063] The insulating base layer includes a first main region and an edge region located outside the first main region; the porosity of the first main region of the insulating base layer is smaller than the porosity of the edge region of the insulating base layer;

[0064] The current collector further comprises a conductive layer, wherein the conductive layer is located between the insulating base layer and the active material layer;

[0065] The conductive layer includes a second main region and an edge region located outside the second main region; the edge region is provided with a through hole;

[0066] An orthographic projection of an edge region of the conductive layer on the insulating base layer at least partially overlaps with an edge region of the insulating base layer.

[0067] A third aspect of the present application is to provide a battery device, which includes the battery cell described in the first aspect or the current collector described in the second aspect.

[0068] A fourth aspect of the present application is to provide an electrical device, which includes the battery device described in the third aspect.

[0069] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0071] Figure 1 Schematic diagram of the battery structure of some embodiments of the present application;

[0072] Figure 2 This is a schematic diagram of the exploded structure of batteries according to some embodiments of the present application;

[0073] Figure 3 A schematic diagram of a vehicle structure according to some embodiments of the present application;

[0074] Figure 4 This is a schematic structural diagram of a battery pack according to some embodiments of the present application;

[0075] FIG5 is a schematic diagram of the structure of the current collector in some embodiments of the present application; wherein, Figure 5A A structural diagram illustrating the positional relationship between the conductive layer and the insulating base layer;

[0076] Figure 5B 、 Figure 5C 、 Figure 5D and Figure 5E Schematic diagrams of specific structures with different positional relationships between the second main region of the conductive layer and the first main region of the insulating base layer;

[0077] FIG6 is a schematic structural diagram of the insulating base layer of the current collector in some embodiments of the present application; wherein, Figure 6A 、 Figure 6B 、 Figure 6C It is a schematic diagram of the structure of the insulating base layer including different areas;

[0078] FIG7 is a schematic diagram of the structure of the conductive layer of the current collector of some embodiments of the present application; wherein, Figure 7A 、 Figure 7B is a schematic structural diagram of a conductive layer including different regions;

[0079] Figure 8 This is a schematic structural diagram of a secondary battery in some embodiments of the present application;

[0080] FIG9 is a schematic diagram of the structure of the negative electrode sheet of some embodiments of the present application; wherein, Figure 9A 、 Figure 9B Mainly used to illustrate the different areas of the negative electrode;

[0081] Figure 10 This is a schematic diagram of the structure of the electrode plates of some embodiments of the present application.

[0082] Figure 11 This is a schematic diagram of the structure of the electrode plates of some embodiments of the present application.

[0083] Figure 12 This is a schematic diagram of the structure of the electrode plates of some embodiments of the present application.

[0084] Figure 13 This is a structural schematic diagram of the positional relationship between the electrode pads and the isolation member in some embodiments of the present application.

[0085] The accompanying drawings in the specific implementation manner are as follows:

[0086] 10000, vehicle;

[0087] 1000, battery; 2000, controller; 3000, motor;

[0088] 100. Battery cell;

[0089] 200, box body; 210, first part; 220, second part;

[0090] 10. Secondary batteries;

[0091] 101. housing; 102. electrode assembly; 103. cover plate;

[0092] 1. Negative electrode sheet; 11. Negative electrode active material layer;

[0093] M-side, N-side: surfaces of the negative electrode active material layer facing each other along the third direction;

[0094] 11A, first region; 11B, second region; 11a, first negative electrode active material layer; 11b, second negative electrode active material layer; 11, negative electrode active material layer; 111, negative electrode active material main body region; 112, negative electrode active material edge thinning region;

[0095] 2. Positive electrode sheet; 21. Positive electrode active material layer; 211. Positive electrode active material main body area; 212. Positive electrode active material edge thinning area;

[0096] 3. Isolation member; 31. Third main body region; 32. Edge region of the isolation member;

[0097] 4. Current collector; 41. Insulating base layer; 411. First main region; 412. Edge region of insulating base layer; 412a. First edge region; 412b. Second edge region;

[0098] Surface A and Surface B: surfaces of the first edge region arranged opposite to each other along the second direction;

[0099] Surface C and Surface D: surfaces of the first main area arranged opposite to each other along the second direction;

[0100] Surface A' and surface B': surfaces of the second edge region that are opposite to each other along the second direction;

[0101] 42, conductive layer; 421, second main region; 422, edge region of the conductive layer; 422a, third edge region; 422b, fourth edge region;

[0102] Surface E and Surface F: surfaces of the third edge region arranged opposite to each other along the second direction;

[0103] G surface and H surface: surfaces of the second main body region arranged opposite to each other along the second direction;

[0104] Surface E' and surface F': surfaces of the fourth edge region arranged opposite to each other along the second direction;

[0105] First direction: the extension direction of the current collector, also refers to the length direction of the current collector or the coordinate axis x direction;

[0106] Second direction: also refers to the width direction of the current collector or the coordinate axis y direction;

[0107] The third direction also refers to the thickness direction of the current collector, the stacking direction, or the coordinate axis z direction. DETAILED DESCRIPTION

[0108] Below, with appropriate reference to the accompanying drawings, the embodiments of the current collector, battery cell, battery device, and electrical device of the present application are described in detail. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0109] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0110] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0111] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0112] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0113] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0114] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0115] Unless otherwise specified, in this application, the terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0116] Unless otherwise specified, in this application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0117] Unless otherwise specified, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0118] Batteries have been widely used in various products due to their advantages such as high energy density, long cycle life, safety and reliability. In recent years, with the significant increase in demand for batteries as energy sources, higher requirements have been placed on battery performance, such as cycle life.

[0119] During the coating process of battery preparation, the active material forms an active material layer on the surface of the current collector. Because the coating at the edge of the current collector is difficult to control, after the battery is formed, the edge of the active material layer will produce a bulging phenomenon. That is, the thickness of the active material layer at the edge is greater than the thickness of the middle region. This phenomenon can easily lead to uneven current distribution during the battery's charge and discharge process, thereby causing polarization. To alleviate this phenomenon, the prior art discloses thinning the edge of the active material layer during the battery preparation process so that the thickness at the edge is less than the thickness of the middle region. However, this design method brings new technical problems: the distance between the edge positions of adjacent active material layers is greater than the distance between the middle regions of adjacent active material layers. The edge positions of the active material layer are easily not fully infiltrated by the electrolyte, which leads to a variety of problems. For example, for lithium-ion batteries, the transmission path of lithium ions at the edge positions of the active material layer is blocked, and this position is severely polarized, the impedance increases, and then purple spots and lithium precipitation appear. The rate of electrolyte consumption is further accelerated, the local aging rate in the battery is accelerated, the battery cycle performance is degraded, and ultimately the battery life is affected.

[0120] Based on the above considerations, in order to improve the cycle life of the battery, the present applicant conducted relevant experimental research and obtained a current collector and battery cell, a battery device and an electrical device.

[0121] First, the present application discloses a battery cell, which includes a current collector and an active material layer located on at least one side of the current collector; the current collector includes an insulating base layer, the insulating base layer includes a first main region, and an edge region located outside the first main region; the porosity of the first main region of the insulating base layer is less than the porosity of the edge region of the insulating base layer; the current collector also includes a conductive layer, which is located between the insulating base layer and the active material layer; the conductive layer includes a second main region, and an edge region located outside the second main region; the edge region of the conductive layer is provided with a through hole; the orthographic projection of the edge region of the conductive layer on the insulating base layer at least partially overlaps with the edge region of the insulating base layer.

[0122] The current collector of the present application is immersed in the electrolyte in the battery cell. Since the edge area of ​​the insulating base layer of the current collector has a relatively higher probability of contact with the electrolyte than the main area, the porosity of the edge area of ​​the insulating base layer is selected in the present application to be larger than the porosity of the first main area of ​​the insulating base layer, thereby facilitating the electrolyte to fully and effectively infiltrate the edge area of ​​the insulating base layer of the current collector. The electrolyte flows from the edge area of ​​the insulating base layer to the edge area of ​​the conductive layer, and further flows to the active material layer, so that the edge position of the active material layer is fully and effectively infiltrated by the electrolyte, alleviating a series of problems such as severe polarization and increased impedance caused by the obstruction of the metal ion transmission path at the edge position of the active material layer. Therefore, the design method provided by the present application improves the cycle life of the battery by improving the uniformity of the current distribution of the battery during the charging and discharging process.

[0123] Therefore, the battery cell provided in this application is conducive to improving user experience.

[0124] Electrode assembly

[0125] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode sheet, a negative electrode sheet, and a separator, which is located between the negative and positive electrodes. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded in and released from the positive and negative electrodes. The separator, located between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0126] Battery device

[0127] The battery apparatus mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells, which are connected in series, parallel, or hybrid via a busbar.

[0128] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells.

[0129] As an example, the battery cell assembly may be a battery module, which is formed by arranging and fixing multiple battery cells to form an independent module. As an example, the battery module may be formed by bundling multiple battery cells with a cable tie.

[0130] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are housed in the case.

[0131] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0132] As an example, the battery cell assembly may also be housed in the box by directly fixing the plurality of battery cells to the box.

[0133] As an example, the housing may include a first housing and a second housing. The first housing and the second housing engage to form an enclosed space within the housing to house the battery cell assembly. Enclosed here means covered or closed, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0134] As an example, the box may include a top cover, a frame, and a bottom plate, wherein the top cover and the bottom plate are respectively connected to the frame to form a closed space inside the box to accommodate the battery cell assembly.

[0135] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0136] The battery cells of the present application may include outer packaging. The outer packaging may be used to encapsulate the electrode assembly and electrolyte composed of the battery cells. The outer packaging of the battery cells may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cells may also be a soft shell, such as a bag-type soft shell. The material of the soft shell may be plastic, and the plastic includes but is not limited to polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0137] The present application has no particular restrictions on the shape of the battery, which can be cylindrical, square or any other shape. For example, Figure 1 The secondary battery 10 is a square structure as an example.

[0138] According to some embodiments of the present application, Figure 2 , the outer packaging may include a shell 101 and a cover plate 103. The shell 101 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 101 has an opening connected to the receiving cavity, and the cover plate 103 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 102 through a winding process or a lamination process. The electrode assembly 102 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 102. The number of electrode assemblies 102 contained in the secondary battery 10 may be one or more, and those skilled in the art can select according to specific actual needs.

[0139] The electrode assembly 102 provided in the present application is applied to a battery cell, which is beneficial to improving the performance of the battery cell. The battery cell can be used as a power source for an electrical device or as an energy storage unit for an electrical device. The electrical device is applied to the power field, such as mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains (such as subways, high-speed railways, trains, EMUs, etc.), ships and satellites, energy storage systems, etc., but not limited to the above-mentioned fields.

[0140] For the convenience of explanation, some embodiments of the present application are described by taking a vehicle as an example of an electrical device.

[0141] Please refer to Figure 3 , Figure 3 A schematic structural diagram of a vehicle 10000 provided for some embodiments of the present application. The vehicle 10000 may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 1000 is provided inside the vehicle 10000. The battery 1000 may be provided at the bottom, head or tail of the vehicle 10000. The battery 1000 may be used to power the vehicle 10000. For example, the battery 1000 may serve as an operating power source for the vehicle 10000. The vehicle 10000 may further include a controller 2000 and a motor 3000. The controller 2000 is used to control the battery 1000 to power the motor 3000. For example, the controller 2000 is used to control the battery 1000 to power the motor 3000, for example, for starting, navigating and operating power requirements of the vehicle 10000 during driving.

[0142] In some embodiments of the present application, the battery 1000 can serve not only as an operating power source for the vehicle 10000, but also as a driving power source for the vehicle 10000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 10000.

[0143] Please refer to Figure 4 , Figure 4 This is an exploded view of a battery 1000 provided in some embodiments of the present application. Battery 1000 includes a housing 200 and a battery cell 100. Conventional battery cells include primary or secondary batteries, but this application specifically protects secondary batteries 10. Battery cell 100 is housed within housing 200. Housing 200 is used to accommodate battery cell 100 and can adopt a variety of structures.

[0144] In some embodiments, the housing 200 may include a first portion 210 and a second portion 220. The first portion 210 and the second portion 220 overlap each other, and the first portion 210 and the second portion 220 together define a storage space for accommodating the battery cells 100. The second portion 220 may be a hollow structure with one end open, and the first portion 210 may be a plate-like structure. The first portion 210 overlaps the open side of the second portion 220, so that the first portion 210 and the second portion 220 together define the storage space. The first portion 210 and the second portion 220 may also be hollow structures with one end open, with the open side of the first portion 210 overlapping the open side of the second portion 220. Of course, the housing 200 formed by the first portion 210 and the second portion 220 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0145] In the battery 1000, there may be multiple battery cells 100, and the multiple battery cells 100 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. The multiple battery cells 100 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery 100 structure may be housed within the housing 200. Of course, the battery 1000 may also be a battery module formed by first connecting multiple battery cells 100 in series, in parallel, or in a hybrid connection, and then the multiple battery modules 1000 are further connected in series, in parallel, or in a hybrid connection to form an entire battery 1000 structure, and then housed within the housing 200. The battery 1000 may also include other structures, for example, the battery 1000 may also include a busbar component for electrically connecting the multiple battery cells 100.

[0146] battery cells

[0147] In some embodiments, the present application discloses a battery cell, which includes a current collector and an active material layer located on at least one side of the current collector; the current collector includes an insulating base layer, the insulating base layer includes a first main region, and an edge region located outside the first main region; the porosity of the first main region of the insulating base layer is less than the porosity of the edge region of the insulating base layer; the current collector also includes a conductive layer, the conductive layer is located between the insulating base layer and the active material layer; the conductive layer includes a second main region, and an edge region located outside the second main region; the edge region of the conductive layer is provided with a through hole; the orthographic projection of the edge region of the conductive layer on the insulating base layer at least partially overlaps with the edge region of the insulating base layer.

[0148] The battery cells of the present application may be secondary batteries, which are batteries that can be recharged to activate the active materials after discharge and continue to be used. The battery cells may be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc., and the embodiments of the present application are not limited thereto.

[0149] The current collector of the present application refers to a structure or component that collects current, which can collect the current generated by the active material of the battery to form a larger current for external output, while its own internal resistance is sufficiently small.

[0150] The insulating base layer of the present application refers to a film layer made of organic insulating polymer material that supports the conductive layer and the active material layer. The insulating base layer can firstly effectively absorb the deformation stress caused by the expansion of the pole piece. Secondly, in the case of a short circuit, the insulating base layer can also provide a larger resistance, reduce the short-circuit current, prevent thermal runaway, and thus improve the safety of the battery.

[0151] The conductive layer of the present application refers to a film layer with conductive ability, which can collect the current generated by the active material of the battery to form a larger current for external output.

[0152] like Figure 5A 、 5B 5C, 5D, and 5E indicate that the current collector 4 of the present application includes an insulating base layer 41 and a conductive layer 42, wherein the conductive layer 42 is located on at least one side surface of the insulating base layer 41. Figures 5A to 5D The conductive layer 42 is only shown on one side of the insulating base layer 41. The battery cell actually discussed in the subsequent specific embodiments of this application includes an insulating base layer 41 and conductive layers 42 located on both sides of the insulating base layer 41. This application will be discussed in detail later. Figures 5B to 5E 4 illustrates a situation where the orthographic projection of the edge region 422 of the conductive layer on the insulating base layer 41 overlaps with the edge region 412 of the insulating base layer. The orthographic projection here refers to an image formed by a parallel projection line of the edge region 422 of the conductive layer perpendicular to the projection plane with the insulating base layer 41 as the projection plane, wherein: Figures 5B to 5D The diagram shows a situation where the orthographic projection of the edge area 422 of the conductive layer on the insulating base layer 41 partially overlaps with the edge area 412 of the insulating base layer. Figure 5E The diagram shows a situation where the orthographic projection of the edge area 422 of the conductive layer on the insulating base layer 41 completely overlaps with the edge area 412 of the insulating base layer. Figure 5E The schematic structure is convenient for the preparation of the current collector and also convenient for the electrolyte to infiltrate the current collector. Figure 5E The schematic structure is described in detail.

[0153] This application Figure 6A 、 Figure 6B and Figure 6C The schematic diagram of the partial structure of the insulating base layer 41 is shown; Figure 7A 、 Figure 7B A partial structural diagram of the conductive layer 42 is shown.

[0154] Combine Figures 6A to 6C It can be seen that the above-mentioned insulating base layer 41 includes a first main body area 411 and an edge area 412 of the insulating base layer located outside the above-mentioned first main body area 411. Figure 6A 、 Figure 6B It can be seen that the first main area 411 is located in the central position of the insulating base layer 41, and the edge area 412 of the insulating base layer is located in the peripheral area of ​​the first main area 411 and is arranged circumferentially along the first main area 411. The orthographic projection shape of the first main area 411 on the insulating base layer 41 includes any shape conventional in the art, such as a regular circle, ellipse, square, or various irregular shapes. Figure 6B Only some structures and shapes are shown in the figure. Figure 6C It can be seen that the edge region 412 of the insulating base layer and the first main region 411 extend along the coordinate axis x direction and are arranged along the coordinate axis y direction. This application will describe this positional relationship in detail below.

[0155] The porosity of this application refers to the percentage of the pore volume in the material to the total volume of the material in its natural state. Generally speaking, the greater the porosity of the material, the larger the pore volume in the material is relatively, and the stronger the ability to store electrolytes is. The method for determining the porosity of the insulating base layer of this application includes any conventional method in the field, such as first obtaining the insulating base layer of the current collector, and the specific steps are as follows: placing the battery cell in a 1.0 mol / L sodium hydroxide aqueous solution at room temperature for discharge treatment, and after the discharge is completed, manually disassembling to obtain the pole piece and the separator;

[0156] A cryo-focused ion beam (FIB) is used to slice the electrode layer by layer at different thickness positions (the smallest scale can reach nanoscale slices), separate the insulating base layer and the conductive layer, and then cut different distribution areas of the insulating base layer to obtain the first main area sample and the edge area sample.

[0157] The porosity of each area was then measured using the following method:

[0158] After drying, each film layer sample was cut into a square sample of about 20 mm × 20 mm. The thickness and actual side length were measured by a digital micrometer and a vernier caliper. The volume V was calculated and the weight M0 was weighed. Then, the square sample was immersed in n-hexadecane reagent. After soaking for 2 hours at room temperature and air atmosphere, it was taken out and the n-hexadecane reagent liquid adsorbed on the surface was sucked off. Then the weight M was weighed. t , then the porosity of each membrane layer satisfies the following mathematical relationship:

[0159] Porosity = (M t -M0) / ρ×V×100%;

[0160] The ρ in the above mathematical relationship is the density of the n-hexadecane reagent, in g / mm 3 , V is the volume of the square sample of each film layer, unit is mm 3 , weight M0 and M t The unit is g, the weight measuring instrument is a thousandth balance, and the models of the thousandth balance, digital display micrometer, and vernier caliper include but are not limited to any conventional models in the art.

[0161] As mentioned above, the design method of thinning the edge position of the active material layer easily leads to the edge position of the active material layer not being fully infiltrated by the electrolyte, thereby obstructing the transmission path of the metal ions, resulting in severe polarization, increased impedance and other series of problems. The porosity of the first main area 411 of the insulating base layer 41 of the present application is less than the porosity of the edge area 412 of the insulating base layer, and the edge area 412 of the insulating base layer of the current collector 4 has a high probability of contact with the electrolyte, so it is convenient for the electrolyte to fully and effectively infiltrate the edge area 412 of the insulating base layer of the current collector 4, thereby alleviating the severe polarization caused by the obstruction of the transmission path of the metal ions at the edge position of the active material layer, increased impedance and other series of problems. Therefore, the design method provided by the present application improves the cycle life of the battery by improving the uniformity of the current distribution during the charging and discharging process.

[0162] In some embodiments, the porosity of the first main region 411 of the insulating base layer 41 is 0-20%, and the porosity of the edge region 412 of the insulating base layer is 10%-40%.

[0163] The first main region 411 of the insulating base layer 41 of the current collector 4 of the present application and the edge region 412 of the insulating base layer each have a certain porosity. The present application discloses a specific numerical range of each porosity in these embodiments. Within this numerical range, it is convenient for the electrolyte to infiltrate the edge of the current collector and further infiltrate the active material layer.

[0164] In these embodiments, the present application discloses that the porosity of the first main region 411 of the insulating base layer 41 is any one of 0, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%, or any one of the above two ranges. In some embodiments, the present application discloses a design in which the porosity of the first main region 411 of the insulating base layer 41 is 0 or relatively small, and this design does not affect the infiltration of the electrolyte into the edge of the current collector.

[0165] In these embodiments, the present application discloses that the porosity of the edge area 412 of the above-mentioned insulating base layer is any one of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or any one of the values ​​in any two ranges above.

[0166] In some embodiments, the first main region 411 of the insulating base layer 41 comprises a porous structure, and the average pore size of the porous structure is 10 nm to 10 μm;

[0167] In some embodiments, the edge region 412 of the insulating base layer includes a porous structure, and the average pore size of the porous structure is 10 nm to 10 μm.

[0168] As mentioned above, the first main area 411 of the insulating base layer 41 of the present application and the edge area 412 of the insulating base layer both have a certain porosity, so the insulating base layer 41 contains various pore structures, such as through holes, non-through holes, etc. These pore structures have a certain pore size. The average pore size of the present application refers to the average value of the pore sizes contained in the various pore structures in the insulating base layer 41. The method for determining the average pore size includes any conventional determination method in the art, such as nitrogen adsorption desorption instrument and mercury intrusion instrument. Specifically, the test instrument used is ASAP2460-physical adsorption analyzer, and the material sample after drying and degassing treatment is placed in liquid nitrogen. Different test pressures are adjusted to measure the adsorption amount of nitrogen respectively, and the adsorption and desorption isotherms are drawn. The shape of the pore is determined according to the shape of the hysteresis loop, the pore distribution is calculated according to different pore models, and the pore size distribution curve of the pore is fitted using the BJH model to obtain the average pore size.

[0169] In some embodiments, the present application lists the average pore diameter of the porous structure contained in the first main region 411 of the insulating base layer 41 and the edge region 412 of the insulating base layer. Specifically, the average pore diameter of the porous structure in the first main region 411 of the insulating base layer 41 is any one of 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, 5000 nm, and 10 μm, or any one of the above two ranges. Similarly, the average pore diameter of the porous structure in the edge region 412 of the insulating base layer is any one of 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, 5000 nm, and 10 μm, or any one of the above two ranges. Since the material, pore size, etc. of the insulating base layer 41 affect its porosity, under the premise that the material of the insulating base layer 41 remains consistent, the average pore size of the porous structure of the first main area 411 of the insulating base layer 41 is smaller than the average pore size of the porous structure of the edge area 412 of the insulating base layer, so that the porosity of the first main area 411 of the insulating base layer 41 is smaller than the porosity of the edge area 412 of the insulating base layer.

[0170] In some embodiments, the insulating base layer includes a first edge region and a second edge region, the first edge region and the second edge region extend along a first direction and are arranged in a second direction, and the first main region is provided between the first edge region and the second edge region; the first direction intersects with the second direction.

[0171] Specifically combined with the above Figure 6C It can be seen that the present application discloses in some embodiments that the insulating base layer 41 includes a first edge area 412a and a second edge area 412b, and a first main area 411 is provided between the first edge area 412a and the second edge area 412b. The first edge area 412a, the second edge area 412b and the first main area 411 extend along the first direction and are arranged in the second direction. The present application discloses in these embodiments that the first direction is the coordinate axis x direction, which also refers to the length direction of the current collector, and the second direction is the coordinate axis y direction, which also refers to the width direction of the current collector. For wound battery cells, the length direction of the current collector refers to the extension direction of the current collector, and the direction intersecting and perpendicular to the extension direction is the width direction of the current collector. For laminated battery cells, the length direction and width direction of the current collector are determined according to the actual length value or width value or actual needs.

[0172] In some embodiments, the present invention selects Figure 6C The schematic structure distinguishes the edge area and the main area of ​​the insulating base layer 41, which not only facilitates the preparation of the current collector, but also helps to control the performance of the current collector. The preparation process of the current collector is described in detail in the subsequent preparation method of the current collector.

[0173] This application discloses in these examples Figure 6CIn the illustrated insulating base layer 41, the average pore size of the porous structure of the above-mentioned first main area 411 is 50nm~2μm; and / or; the porosity of the above-mentioned first main area 411 is greater than zero and less than or equal to 18.5%, and / or; the average pore size of the porous structure of the above-mentioned first edge area 412a and the second edge area 412b is 500nm~4μm; and / or; the porosity of the above-mentioned first edge area 412a and the second edge area 412b is independently selected from 15%~40%.

[0174] This application discloses in these examples Figure 6C The specific parameters of the average pore size and porosity of each edge area and main area in the illustrated insulating base layer 41 are within the parameter range, which facilitates the infiltration of the electrolyte into the electrode and is conducive to better improving the cycle life of the battery.

[0175] In some embodiments, further combined Figure 6C , along the second direction, the first edge region 412a includes an A surface and a B surface arranged opposite to each other, and the distance between the A surface and the B surface is W1; along the second direction, the first main region 411 includes a C surface and a D surface arranged opposite to each other, and the distance between the C surface and the D surface is W2; along the second direction, the second edge region 412b includes an A' surface and a B' surface arranged opposite to each other, and the distance between the A' surface and the B' surface is W3; this application is Figure 6C The diagram illustrates that surfaces B and C are coplanar. Similarly, surfaces D and B' are coplanar. This application uses different symbols to illustrate the interface between the various intervals, but these symbols are meaningless. Furthermore, the distance W2 between surfaces C and D, the distance W1 between surfaces A and B, and the distance W3 between surfaces A' and B' satisfy the following: W2:W1:W3 = 6-8:1-2:1-2.

[0176] In these embodiments, the present application controls the specific dimensions of the edge regions and the main region on the insulating base layer 41 , which not only facilitates the preparation of the current collector but also helps control the performance of the current collector.

[0177] In these embodiments, the present application discloses that W2:W1:W3 is any one of 6:1:1, 7:1:1, 8:1:1, 6:2:1, 7:2:1, 8:2:1, 6:1:2, 7:1:2, 8:1:2, 6:2:2, 7:2:2, 8:2:2 or any one of the ranges of any two of the above.

[0178] In some embodiments, the conductive layer includes a second main region, an edge region of the conductive layer is provided with a through hole, and the second main region of the conductive layer is not provided with a hole.

[0179] Combine Figure 7A and Figure 7B It can be seen that the conductive layer 42 includes a second main area 421, which has no through-holes, and an edge area 422 of the conductive layer. As described above for the first main area 411 of the insulating base layer 41, the meaning of the second main area 421 of the conductive layer 42 remains the same as above. The advantages of the present application choosing to provide through-holes in the edge area 422 of the conductive layer and not providing through-holes in the second main area 421 include: the electrolyte flows from the edge area 412 of the insulating base layer to the edge area 422 of the conductive layer, and further flows to the active material layer, so that the edge position of the active material layer is fully and effectively infiltrated by the electrolyte. At the same time, as mentioned above, the function of the conductive layer 42 is mainly to collect the current generated by the active material of the battery in order to form a larger current for external output. In order to facilitate the flow of the electrolyte, the present application also chooses to open a through-hole in the edge area 422 of the conductive layer. At the same time, in order to reduce the impact of the through-hole on the current transported by the conductive layer 42, the present application further chooses not to provide a hole in the second main area 421 of the conductive layer 42.

[0180] The present application does not illustrate through holes in the drawings, but in fact through holes of various shapes are within the protection scope of the present application.

[0181] In some embodiments, the average pore diameter of the through holes is 100 nm to 10 μm.

[0182] The through holes provided in the edge region 422 of the conductive layer of the present application include holes opened along the thickness direction of the conductive layer, and can also be other holes. These holes facilitate the delivery of electrolyte to the active material layer while minimizing the impact on the current transported by the conductive layer. In these embodiments, the present application discloses that the average pore diameter of the through holes is any one of 100nm, 500nm, 1000nm, 5000nm, and 10μm, or any range of any two of the above values.

[0183] In some embodiments, combined Figure 7B The conductive layer 42 includes a third edge region 422a and a fourth edge region 422b, which extend along the first direction and are arranged in the second direction. The second main region 421 is provided between the third edge region 422a and the fourth edge region 422b. The first direction intersects with the second direction. The first direction and the second direction described in these embodiments of the present application are the same as those described above and are not described in detail in this application. Figure 7B The schematic structure distinguishes the edge area and the main area of ​​the insulating base layer 41, which not only facilitates the preparation of the current collector, but also helps to control the performance of the current collector. The preparation process of the current collector is described in detail in the subsequent preparation method of the current collector.

[0184] In some embodiments, Figure 7B In the illustrated conductive layer 42 , a through hole is provided in the edge region 422 of the conductive layer. The average pore diameter of the through hole is 200 nm to 5 μm.

[0185] In some embodiments, Figure 7B In the schematic conductive layer 42, along the above-mentioned second direction, the above-mentioned third edge region 422a includes an E surface and an F surface arranged opposite to each other, and the distance between the E surface and the F surface is T1; along the above-mentioned second direction, the second main region 421 includes a G surface and an H surface arranged opposite to each other, and the distance between the G surface and the H surface is T2; along the above-mentioned second direction, the above-mentioned fourth edge region 422b includes an E' surface and an F' surface arranged opposite to each other, and the distance between the E' surface and the F' surface is T3; the distance T2 between the G surface and the H surface and the distance T1 between the E surface and the F surface and the distance T3 between the E' surface and the F' surface of the present application satisfy: T2:T1:T3=6~8:1~2:1~2.

[0186] In these embodiments, the present application controls the specific sizes of the edge regions and the main region on the conductive layer 42 , which not only facilitates the preparation of the current collector but also helps control the performance of the current collector.

[0187] In these embodiments, the present application discloses that T2:T1:T3 is any one of 6:1:1, 7:1:1, 8:1:1, 6:2:1, 7:2:1, 8:2:1, 6:1:2, 7:1:2, 8:1:2, 6:2:2, 7:2:2, 8:2:2, or any one of the ranges of any two of the above.

[0188] In some embodiments, the conductive layer 42 is formed on the insulating base layer 41 in the present application by any one or more methods including mechanical rolling, bonding, vapor deposition, chemical plating, and electroplating.

[0189] In some embodiments, the material of the insulating base layer 41 includes any one or more of a polymer material and a polymer composite material. The polymer material includes any one or more of poly(terephthalate), polyethylene, polypropylene, epoxy resin, polyamide, polyimide, polyester, polyolefin, polyacetylene, siloxane polymer, polyether, polyol, polysulfone, polysaccharide polymer, amino acid polymer, polysulfur nitride polymer, and aromatic polymer. The polymer material also includes aromatic heterocyclic polymers, epoxy resin, phenolic resin, their derivatives, their cross-linked products, and their copolymers. A polymer composite material refers to two or more polymer materials.

[0190] In some embodiments, the polymer material includes one or more of polycaprolactam (commonly known as nylon 6), polyhexamethylene adipamide (commonly known as nylon 66), polyparaphenylene terephthalamide (PPTA), polymetaphenylene diamine (PMIA), and polyethylene terephthalate (PET). Or polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycarbonate (PC), polyethylene (PE), polypropylene (PP), poly(propylene-ethylene) (PPE), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTEE), polystyrene sulfonate (PSS), polyacetylene (PA), silicone rubber, polyoxymethylene (POM), polyphenylene ether (PPO), polyphenylene sulfide (PPS), polyethylene glycol (PEG), cellulose, starch, protein, polyphenylene, polypyrrole (PPy), polyaniline (PAN), polythiophene (PT), polypyridine (PPY), acrylonitrile-butadiene-styrene copolymer (ABS) and its derivatives, cross-linked products thereof, and copolymers thereof.

[0191] In some embodiments, the insulating base layer 41 may be a single layer or multiple layers. For a multi-layer insulating base layer 41 , the materials of each layer may be the same or different.

[0192] In some embodiments, the conductive layer 42 includes a metal, which includes any one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, iron alloy, titanium, titanium alloy, silver, and silver alloy.

[0193] The thickness of the insulating base layer and the thickness of the conductive layer of the present application remain the same as conventional designs in the art.

[0194] In some embodiments, the insulating base layer 41 and the conductive layer 42 extend along a first direction and are stacked in a third direction; the first direction intersects the third direction. In this application, the first direction is the x-axis, also referred to as the length direction of the current collector, and the third direction is the z-axis, also referred to as the thickness direction of the film layer or the stacking direction of the film layer. Along the third direction, the insulating base layer 41 has a thickness of 25 μm to 50 μm; and / or, along the third direction, the conductive layer 42 has a thickness of 3 μm to 10 μm.

[0195] This application selects an insulating base layer and a conductive layer with appropriate thickness, which can not only play the intrinsic function of the current collector, but also facilitate the response to the adverse effects caused by the expansion of the pole piece.

[0196] In these embodiments, the present application discloses that the thickness of the insulating base layer 41 is any one of 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, and 50 μm, or any one of the ranges of any two of the above values.

[0197] In these embodiments, the present application discloses that the thickness of the conductive layer 42 is any one of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm, or any one of the ranges of any two of the above values.

[0198] In some embodiments, the present application further discloses forming a conductive carbon layer on at least one side of the conductive layer 42. The conductive carbon layer comprises conductive carbon and is formed on the surface of the conductive layer 42 by coating. The main region and edge regions of the conductive carbon layer are configured in the same manner as the conductive layer 42, and the openings are positioned and formed in the same manner as the conductive layer 42. This conductive carbon layer improves the bonding between the conductive layer 42 and the active material layer, while not affecting the electrolyte's wetting of the electrode sheet, and further enhances interfacial stability.

[0199] The present application also discloses, in some embodiments, that a protective layer is provided between the conductive layer 42 and the insulating base layer 41, and the protective layer includes a metal oxide protective layer; the metal oxide protective layer has high mechanical strength, strong corrosion resistance, and a large specific surface area, and is conducive to increasing the bonding ability between the conductive layer 42 and the insulating base layer 41. The material of the metal oxide protective layer includes any one or more of aluminum oxide, cobalt oxide, nickel oxide, and chromium oxide. The formation method of the protective layer of the present application includes any one or more of vapor deposition, in-situ formation, and coating methods. At the same time, the main area and the edge area of ​​the protective layer are arranged in the same manner as the insulating base layer 41, and the opening position and method are also the same as the insulating base layer 41. The protective layer is conducive to improving the bonding ability between the conductive layer 42 and the insulating base layer 41 and further improving the interface stability without affecting the infiltration of the electrolyte into the electrode.

[0200] In some embodiments, the present application discloses an electrode sheet formed by the above-mentioned current collector 4 and the active material layer.

[0201] In some embodiments, the electrode plate includes a positive electrode plate or a negative electrode plate, and the electrode plate includes a current collector 4 and an active material layer located on at least one side of the current collector 4.

[0202] The positive electrode sheet 2, separator 3 and negative electrode sheet 1 of the present application can be wound or laminated to form a secondary battery. Figure 8 The secondary battery 10 is formed by a winding method, and the Figure 8 It can be seen that a negative electrode sheet 1 or a positive electrode sheet 2 is placed between two adjacent separators 3, and the negative electrode sheets 1 and the positive electrode sheets 2 are alternately arranged in the stacking direction (z direction of the coordinate axis). The number and size of the negative electrode sheets 1 and / or the positive electrode sheets 2 can be selected according to actual conditions, and this application will not elaborate on them. Figure 8Only one winding method is illustrated; other lamination or winding methods are within the scope of protection of this application. The active material layer of this application may be formed on the surface of the current collector 4 by any conventional method in the art, such as coating or deposition. Coating may include any one or more of roll coating, extrusion coating, blade coating, and gravure coating. Deposition may include any one or more of physical deposition and chemical deposition.

[0203] In some embodiments, the present application takes the negative electrode sheet as an example to specifically describe the positional relationship between the negative electrode active material layer and the current collector.

[0204] In some embodiments, combined Figure 9A It can be seen that the above-mentioned current collector 4 and the above-mentioned negative electrode active material layer 11 extend along the first direction and are stacked in the third direction; the first direction intersects with the third direction; the first direction and the third direction here remain the same as the above description, and are not repeated in this application.

[0205] Along the third direction, the negative electrode active material layer 11 includes an M face and an N face that are opposite to each other. The M face is located close to the current collector 4, and the distance between the M face and the N face is H. The region extending from the M face to 0.1×H is formed as a first region 11A, and the region extending from the N face to 0.1×H is formed as a second region 11B. The first region 11A includes a first negative electrode active material, and the second region 11B includes a second negative electrode active material. The median particle size of the first negative electrode active material is smaller than the median particle size of the second negative electrode active material. In this design, the particle size of the active material particles in the first region close to the current collector is small, and the particle size of the active material particles in the second region away from the current collector is large. Compared with the pores formed between the small particles, the pores between the large particles are large, and the tortuosity of the path connecting the large pores is also small. Under the same compaction density, the electrolyte will preferentially infiltrate between the electrode layers along the path with larger pore size and smaller tortuosity during the infiltration process. Therefore, the design provided in the present application accelerates the infiltration between the electrolyte and the active material particles in the second region away from the current collector, and further accelerates the infiltration of the electrolyte into the active material in the first region. As mentioned above, the current collector of the present application is immersed in the electrolyte, and the electrolyte flows from the edge area of ​​the insulating base layer to the edge area of ​​the conductive layer, and further flows to the active material layer. Therefore, the electrolyte fully and effectively infiltrates different intervals of the entire active material layer. Therefore, the design provided in the present application improves the cycle life of the battery by improving the uniformity of the current distribution of the battery during charging and discharging.

[0206] In some embodiments, as Figure 9BSchematically, the current collector 4 and the negative electrode active material layer 11 extend along a first direction and are stacked in a third direction; the first direction intersects with the third direction; along the third direction, the negative electrode active material layer 11 includes a first negative electrode active material layer 11a arranged close to the current collector, and a second negative electrode active material layer 11b located on the surface of the first negative electrode active material layer 11a away from the current collector 4; the first negative electrode active material layer 11a includes a first negative electrode active material, and the second negative electrode active material layer 11b includes a second negative electrode active material; the median particle size of the first negative electrode active material is smaller than the median particle size of the second negative electrode active material.

[0207] In the above, this application uses the negative electrode active material layer 11 as an example to describe the particle size of the negative electrode active material in the first region 11A arranged close to the current collector 4 and the second region 11B arranged away from the current collector 4. In fact, the positive electrode active material layer can also adopt the same or similar design as the negative electrode active material layer, and this application will not go into details here.

[0208] In some embodiments, the positive electrode active material layer and the negative electrode active material layer are respectively located on both sides of the current collector.

[0209] In some embodiments, the positive electrode active material layer and the negative electrode active material layer are simultaneously located on both sides of the current collector. Figure 10 It can be seen that the two opposite surfaces of the current collector 4 are respectively provided with a negative electrode active material layer 11 and a positive electrode active material layer 21. This design adopted in the present application is conducive to further improving the energy density of the battery.

[0210] In some embodiments, the current collector and the active material layer extend along a first direction and are stacked in a third direction; the first direction intersects the third direction;

[0211] The active material layer includes an active material main body region and an edge thinning region located outside the active material main body region;

[0212] The orthographic projection of the edge thinning region on the current collector at least partially overlaps with the edge region of the conductive layer.

[0213] The third direction of the present application refers to the thickness direction of the current collector or the stacking direction of the pole pieces, and the coordinate axis z direction is illustrated in the drawings of the specification.

[0214] In some embodiments, combined Figure 11It can be seen that the above-mentioned negative electrode plate 1 includes a negative electrode current collector 4 and a negative electrode active material layer 11 located on at least one side of the surface of the above-mentioned negative electrode current collector 4; the negative electrode active material layer 11 includes a negative electrode active material main area 111 and a negative electrode active material edge thinning area 112; the negative electrode active material main area 111 of the present application and the first main area 411 of the above-mentioned current collector 4 have the same meaning, and the positions also correspond. Specifically, the positive projection of the above-mentioned negative electrode active material edge thinning area 112 on the above-mentioned current collector 4 at least partially overlaps with the edge area 412 of the above-mentioned current collector. Similarly, the positive electrode active material layer 21 includes a positive electrode active material main area 211 and a positive electrode active material edge thinning area 212; the positive electrode active material main area 211 of the present application and the first main area 411 of the above-mentioned current collector 4 have the same meaning, and the positions also correspond. Specifically, it can be as follows Figure 12 Here, at least partial overlap includes complete overlap, and the present application will be described mainly in terms of a complete overlap design in subsequent specific embodiments.

[0215] This application is in Figure 11 It is described in the specification that the negative electrode active material layer 11 includes a main body area and an edge thinning area. This design method is convenient and effective in reducing the probability of bulging edges at the edge of the negative electrode active material layer, thereby improving the uniformity of current distribution during the charge and discharge process of the battery to increase the cycle life of the battery. Similarly, this application Figure 12 It is described that the positive electrode active material layer 21 includes a main area and an edge thinning area. This design method also effectively reduces the probability of bulging edges appearing at the edge of the positive electrode active material layer, and improves the uniformity of current distribution during the charge and discharge process of the battery to increase the cycle life of the battery.

[0216] In these embodiments of the present application, during the preparation process, the coating thickness of the main positive electrode active material region 211 is h1, and the coating thickness of the thinned positive electrode active material edge region 212 is h2; and the following conditions are met: h1 / h2 = 1.01 to 1.15. In these embodiments, during the preparation process, the coating thickness of the main negative electrode active material region 111 is h1', and the coating thickness of the thinned negative electrode active material edge region 112 is h2'; and the following conditions are met: h1' / h2' = 1.01 to 1.15. The coating thickness herein refers to the distance between two opposing end surfaces along the third direction of the coordinate axis, and specifically refers to the coating thickness after production.

[0217] In some embodiments, the battery cell includes an isolating member, which includes a third main body area and an edge area located outside the third main body area; the positive projection of the edge area of ​​the isolating member on the insulating base layer at least partially overlaps with the edge area of ​​the insulating base layer; the porosity of the edge area of ​​the isolating member is 70% to 80%.

[0218] Combine Figure 13It can be seen that in some embodiments, the isolation member 3 includes a third main region 31 and an edge region 32 located outside the third main region 31, and the orthographic projection of the edge region 32 of the isolation member on the conductive layer 42 at least partially overlaps with the edge region 422 of the conductive layer; Figure 13 Only the edge area 32 of the single-side separator of the separator 3 is illustrated. In fact, the edge area on the other side also exists, and the at least partial overlap here includes complete overlap, and this application is mainly described in the design mode of complete overlap in subsequent specific embodiments. The present application further selects the porosity of the edge area of ​​the separator to be 70% to 80%, so that the edge position of the active material layer can store sufficient electrolyte and further improve the cycle life of the battery. The meaning and measurement method of the porosity of the separator of this application remain the same as above, and this application will not be repeated here.

[0219] The present application discloses in some embodiments that the porosity of the third main region 31 of the separator 3 is 50% to 60%.

[0220] The present application discloses in these embodiments that the porosity of the edge region 32 of the insulator is any one of 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80% or any one of the ranges of any two of the above values.

[0221] The present application discloses in these embodiments that the porosity of the edge region 32 of the insulator is any one of 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60% or any one of the ranges of any two of the above values.

[0222] Preparation method of current collector

[0223] Some embodiments of the present application disclose a method for preparing a current collector, including the following process:

[0224] Preparation of the insulating base layer: an organic polymer material is extruded through a twin-screw extruder to obtain a high-temperature melt, the high-temperature melt is accurately metered by a melt pump and fed into a die, the high-temperature melt flowing out of the slit of the die passes through a chilled roller to obtain an extruded cast sheet, the extruded cast sheet is fed into a bidirectional asynchronous stretching machine to be stretched a certain multiple in the longitudinal direction, and then the main region and edge region of the cast sheet are stretched separately in the width direction. For example, if the stretching multiple of the main region of the cast sheet in the width direction is a and the stretching multiple of the edge region is b, then a is less than or equal to b, so that the porosity of the main region of the formed insulating base layer is less than the porosity of the edge region;

[0225] The prepared insulating base layer is placed in a high-temperature shaping device and kept warm for a certain period of time to fully remove the membrane stress, thereby obtaining a finished insulating base layer; and then it is cut to the required size according to the battery specifications.

[0226] Preparation of a conductive layer: After the insulating base layer prepared above is cleaned by acid washing, alkali washing, etc., it is placed in a vacuum evaporation chamber, a mask is placed in the edge area of ​​the insulating base layer, and a conductive metal is deposited on at least one side surface of the insulating base layer at a high temperature of 1300℃~2000℃. The edge area of ​​the conductive layer prepared contains through holes, and the main area of ​​the conductive layer does not contain through holes.

[0227] [Positive electrode]

[0228] According to some embodiments of the present application, as described above, the positive electrode sheet includes a current collector and a positive electrode active material layer located on at least one side of the current collector, wherein the positive electrode active material layer includes a positive electrode active material.

[0229] According to some embodiments of the present application, when the positive electrode plate is used in a lithium-ion battery, the positive electrode active material includes but is not limited to one or a combination of two or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and an olivine-structured lithium-containing phosphate; wherein the structural formula of the olivine-structured lithium-containing phosphate is: LiFe 1-x-y Mn x M y PO4, 0≤x≤1, 0≤y<1, 0≤x+y≤1, M includes one or a combination of two or more transition metal elements or non-transition metal elements other than Fe and Mn, and M further includes any one or more of Cr, Mg, Ti, Al, Zn, W, Nb, and Zr.

[0230] This application specifically includes but is not limited to LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 CO 0.2 Mn 0.2 O2(NCM622),LiNi 0.8 CO 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 CO 0.15 Al 0.05 Any one or more of O2, LiFePO4 (LFP) and LiMnPO4.

[0231] According to some embodiments of the present application, when the positive electrode plate is used in a sodium ion battery, the positive electrode active material includes but is not limited to at least one of a sodium transition metal oxide, a polyanionic compound, and a Prussian blue compound. Among them, in the sodium transition metal oxide, the transition metal can be any one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The sodium transition metal oxide is, for example, Na x MO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0<x≤1. Polyanionic compounds include sodium vanadium trifluorophosphate (Na3V2(PO4)2F3), sodium vanadium fluorophosphate (NaVPO4F), sodium vanadium phosphate (Na3V2(PO4)3), Na4Fe3(PO4)2P2O7, NaFePO4, and any one or more thereof. Prussian blue compounds are Na x M1M2(CN)6, wherein M1 and M2 are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, and 0<x≤2.

[0232] According to some embodiments of the present application, the positive electrode active material layer further includes a conductive agent, a binder, etc. The conductive agent includes but is not limited to any one or more of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene and carbon nanofibers. The binder includes but is not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorine-containing acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc. The positive electrode current collector in this application is as described above, and this application will not be repeated here.

[0233] The positive electrode current collector in this application is as described above, and will not be elaborated here.

[0234] The method for forming the positive electrode active material layer of the present application comprises mixing the above raw materials with a solvent (such as nitrogen methyl pyrrolidone) in a certain mass ratio to form a positive electrode slurry, uniformly coating the positive electrode slurry on both sides of the current collector; controlling a certain single-side coating weight; and after drying, using a cold press to compact to a certain compaction density (2.4g / cm 3 ~3.4g / cm 3 ), that is, a positive electrode sheet containing a positive electrode active material layer is obtained.

[0235] [Negative electrode]

[0236] The negative electrode sheet of the present application includes a current collector and a negative electrode film layer located on one or both surfaces of the current collector. Generally speaking, the negative electrode film layer is located on both surfaces of the current collector and is formed by coating or deposition. This application will subsequently use both sides as an example.

[0237] In some embodiments, the present application discloses that the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes one or more of a carbonaceous material, a silicon-based material, a silicon-carbon composite material, a tin-based material, and an alloy thereof. The carbonaceous material in the present application includes one or a combination of two or more of artificial graphite, natural graphite, soft carbon, and hard carbon. Among them, artificial graphite, natural graphite, soft carbon, hard carbon, etc. include materials of any form conventional in the art, and include any manufacturers and models conventional in the art. The silicon-based material in the present application includes one or two of silicon-oxygen materials or silicon-carbon materials, or silicon-carbon composites. The tin-based and alloy materials in the present application include but are not limited to Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, etc. The present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for lithium-ion batteries or sodium-ion batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0238] The present application discloses in some embodiments that the conductive agent comprises one or more of a point-shaped conductive agent, a linear conductive agent, and a planar conductive agent, wherein the point-shaped conductive agent comprises one or more of conductive carbon black (Super P or Super S), acetylene black, conductive graphite (KS-6 or KS-15 or SFG-6 or SFG-15), and Ketjen black, the linear conductive agent comprises one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers, and the planar conductive agent comprises but is not limited to graphene.

[0239] In some embodiments, the present application discloses that the negative electrode active material layer includes a binder and a dispersant, etc. The binder includes but is not limited to polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, polyethylene oxide, polyacrylic acid, polyacrylamide, sodium alginate, styrene-butadiene rubber (SBR), etc. The dispersant also includes any conventional type in the art, such as cellulose and its salts, specifically including but not limited to methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.

[0240] The negative electrode current collector in this application is as described above, and will not be elaborated here.

[0241] The method for forming the negative electrode active material layer of the present application comprises mixing the above raw materials with a solvent (such as deionized water) in a certain mass ratio to form a negative electrode slurry, defoaming the negative electrode slurry, and evenly coating the negative electrode slurry on both sides of the negative electrode current collector; controlling the coating weight on one side; drying, and compacting the negative electrode slurry to a certain compaction density (greater than or equal to 1.65g / cm 3 ), that is, a negative electrode sheet including a negative electrode active material layer is obtained.

[0242] [Isolator]

[0243] Some embodiments of the present application disclose an isolator. The present application does not impose any particular restriction on the type of isolator, and any known porous isolator with good chemical stability and mechanical stability may be selected.

[0244] In some embodiments, the separator includes a base material layer and a coating disposed on the surface of the base material layer; the base material of the base material layer includes one or more of polyethylene, polypropylene, poly(p-phenylene terephthalamide), polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, and polyamide; and the coating includes an inorganic coating and / or an organic coating. The base material layer has good permeability to metal ions, facilitating the migration of metal ions; the coating is disposed on the surface of the base material layer, which can further enhance the mechanical properties of the separator. Furthermore, the inorganic coating includes a ceramic coating, wherein the ceramic particles in the ceramic coating include one or more of SiO2, Al2O3, AlOOH, CaO, TiO2, MgO, ZnO, ZrO2, Mg(OH)2, and BaSO4. The ceramic coating of the present application acts as an insulator, reducing the probability of a short circuit caused by puncturing the separator. In other words, the present application utilizes a separator including a ceramic coating, which first reduces the probability of a short circuit. Even if a short circuit occurs, the current collector of the above-described design of the present application can quickly shut off the short circuit, thereby improving safety.

[0245] In some embodiments, the organic coating comprises an organic polymer coating, wherein the polymer material of the organic polymer coating comprises one or more of polyethylene (PE), polypropylene (PP), poly(p-phenylene terephthalamide) (PPTA), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polyimide (PI), and polyamide (PA). The polymer coating layer can be made of the same material as or a different material than the substrate layer. The thickness of the polymer coating layer and the substrate layer can be different. Furthermore, the thickness of the polymer coating layer is less than the thickness of the substrate layer.

[0246] In other embodiments, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0247] [Electrolytes]

[0248] In some embodiments of the present application, an electrolyte is disclosed. The electrolyte of the present application can be liquid, solid, or gel. Among them, the solid state is a solid electrolyte, the liquid state is a liquid electrolyte, and the gel state is a gel electrolyte. The lithium-ion battery of the present application uses a liquid electrolyte, that is, an electrolyte. The electrolyte contains an electrolyte salt and an organic solvent. Among them, the types of electrolyte salts include any conventional types in the art, for example, including but not limited to inorganic metal salts such as RClO4, RAsF6, RPF6, RBF4, RSbF6, RSO3F, RN(FSO2)2, etc.; fluorine-containing organic metal salts, such as RCF3SO3, RN(FSO2)(CF3SO2), RN(CF3SO2)2, RN(C2F5SO2)2, cyclic 1,3-hexafluoropropane disulfonyl imide lithium, cyclic 1,2-tetrafluoroethane disulfonyl imide lithium, RN(CF3SO2)(C4F9S O2), RC(CF3SO2)3, RPF4(CF3)2, RPF4(C2F5)2, RPF4(CF3SO2)2, RPF4(C2F5SO2)2, RBF2(CF3)2, RBF2(C2F5)2, RBF2(CF3SO2)2, RBF2(C2F5SO2)2, etc.; and metal salts containing dicarboxylic acid complexes, such as lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, etc. The metal and R here contain lithium ions or sodium ions.

[0249] According to some embodiments of the present application, the concentration of the electrolyte salt in the electrolyte is 0.1 mol / L to 4 mol / L. In these embodiments, the present application discloses that the concentration of the electrolyte salt is any one of 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.5 mol / L, 3.8 mol / L, and 4 mol / L, or any one of the values ​​satisfying the above ranges.

[0250] As described above, the organic solvent includes any one or more of carboxylate compounds, carbonate compounds, and ether compounds. Among them, the carboxylate compounds include one or more of ethyl acetate (EA), methyl acetate (MA), ethyl propionate (EP), propyl acetate (PA), methyl propionate (MP), methyl butyrate (MB), ethyl butyrate (EB), and 1,4-butyrolactone (GBL); the carbonate compounds include one or more of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), and fluoroethylene carbonate (FEC). The ether compounds include at least one of tetrahydrofuran, dimethyltetrahydrofuran, tetrahydropyran, dimethyltetrahydropyran, 1,2-dimethoxyethane, dipropylene glycol dimethyl ether, and dimethyl phthalate. The organic solvents of the present application further include one or both of nitrile solvents and sulfone solvents. Nitrile solvents include one or more of acetonitrile (AN), glutaronitrile (GLN), and adiponitrile (ADN). Sulfone solvents include at least one of sulfolane (SF), dimethyl sulfone (MSM), ethylmethyl sulfone (EMS), and diethyl sulfone (ESE), or a combination of two.

[0251] According to some embodiments of the present application, the electrolyte further includes a film-forming stabilizer, which includes a positive electrode film-forming stabilizer and a negative electrode film-forming stabilizer, wherein the positive electrode film-forming stabilizer includes a carbonate additive and / or a sulfate additive, and the carbonate additive includes one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC) and dioctyl carbonate (CC). The sulfate additive includes a cyclic sulfonate additive and / or an alkyl sulfate additive; further, the cyclic sulfonate additive includes one or more of 1,3-propane sultone (PS), propylene sultone (PES), and 3-fluoro-1,3-propane sultone (FPS); the alkyl sulfate additive includes one or more of vinyl sulfate (DTD), diethyl sulfate (DES) and dimethyl sulfate (DMS). The negative electrode film-forming stabilizer includes one or more of a boron lithium salt or sodium salt, a phosphorus-containing lithium salt or sodium salt, and a sulfur-containing lithium salt or sodium salt; the boron-containing lithium salt or sodium salt includes one or more of lithium or sodium tetrafluoroborate (LiBF4, NaBF4), lithium or sodium bisoxalatoborate (LiBOB, NaBOB), and lithium or sodium bisfluorooxalatoborate (LiDFOB, NaDFOB); the phosphorus-containing lithium salt or sodium salt includes one or more of lithium or sodium difluorophosphate (LiPO2F2, NaPO2F2), lithium or sodium fluorophosphate (Li2PO3F, Na2PO3F), and lithium or sodium phosphate (Li3PO4, Na3PO4). The sulfur-containing lithium salt or sodium salt includes one or more of lithium or sodium fluorosulfonate (LiFSO3, NaFSO3), lithium or sodium sulfate (Li2SO4, Na2SO4), and lithium or sodium sulfamate (LiSO3NH2, NaSO3NH2).

[0252] In some embodiments, the electrolyte further comprises an ionic liquid additive, wherein the cation of the ionic liquid additive comprises any one or more of nitrogen-containing onium ions and phosphonium-containing onium ions, and the anion of the ionic liquid additive comprises any one or more of halogen ions, phosphate ions, borate ions, and sulfonimide anions.

[0253] In this application, the electrolyte is the carrier of ion transport in the battery, and plays the role of conducting ions between the positive and negative electrodes of the battery. The type of electrolyte affects the safety of the battery. Ionic liquid additives refer to salts that are added to the electrolyte in a relatively small amount, are composed entirely of cations and anions, and are liquid at room temperature or near room temperature, where room temperature refers to 25°C ± 5°C. Ionic liquid additives themselves have high thermal stability and low volatility. At the same time, the ionic liquid additives can also improve the stability of the negative electrode active material by forming a solid electrolyte interface film (SEI) and improving the stability of the film, thereby improving the safety of the battery.

[0254] In some embodiments, the cation of the ionic liquid additive comprises 1-butyl-3-methylimidazolium ([Bmin] + )、1-benzyl-3-methylimidazolium ([Bzmin] + ), 3-methyl-1-ethoxycarbonylmethylimidazolium ([Etmim] + )、1-alkyl-3-methylimidazolium ([Cnmim] + ), 1-[(trimethylsilyl)methyl]benzotriazolium ([SiMBIM] + )、N-alkyl-N-methylpiperidinium ([CnC1pip] + ), 5-azoniaspiro[4.4]nonane ([AS[mn]] + ), trihexyl (tetradecyl) phosphine ion ([Tf2N] + ), tetrabutylphosphine ion ([Pnnnn] + ), n-butyl-N-methylpyrrolidinium ([Pyr 14 ] + ) can be one or more of tetrabutylphosphine ion or n-butyl-N-methylpyrrolidinium.

[0255] In some embodiments, the anion of the ionic liquid additive comprises a chloride ion ([Cl] - ), bromide ion ([Br] - ), iodide ion ([I] - ), hexafluorophosphate ([PF6] - ), tetrafluoroborate ([BF4] - ), dicyandiamide anion ([N(CN)2] - ), bis(fluorosulfonyl)imide anion ([FSI] - ), bis(trifluoromethylsulfonyl)imide ([TFSI] - ) can be one or more of hexafluorophosphate or bis(fluorosulfonyl)imide anion.

[0256] In some embodiments, the ionic liquid additive includes one or more of tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imide, n-butyl-N-methylpyrrolidine hexafluorophosphate, n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-benzyl-3-methylimidazolium bis(fluorosulfonyl)imide, and can be tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imide, n-butyl-N-methylpyrrolidine hexafluorophosphate, and n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imide.

[0257] The secondary battery of the present application will be described in detail below with reference to specific embodiments.

[0258] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0259] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0260] The present application can adopt conventional techniques of inorganic chemistry within the art. In the following examples, efforts have been made to ensure the accuracy of the numbers used (including amounts, temperatures, reaction times, etc.), but some experimental errors and deviations should be considered. The temperatures used in the following examples (in degrees Celsius) are expressed in ° C, and the pressures are atmospheric pressure or near atmospheric pressure. All pharmaceutical reagents were purchased as AR grade, and all reactions were carried out under argon protection. Unless otherwise noted, all reagents were obtained from commercial sources.

[0261] Experimental materials:

[0262] The materials of the positive electrode active material, the negative electrode active material, the conductive layer and the insulating base layer are all commercially available.

[0263] Preparation Example 1

[0264] A method for preparing a current collector is provided, the method comprising the following steps:

[0265] S100, preparing an insulating base layer: an organic polymer material (polypropylene particles) is extruded through a twin-screw extruder at a temperature of 180° C. to obtain a high-temperature melt. The high-temperature melt is accurately metered by a melt pump and fed into a die. The high-temperature melt flowing out of the die slit passes through a chilled roller to obtain an extruded sheet. The sheet is stretched 3 times in the length direction (coordinate axis x direction) using a bidirectional asynchronous stretching machine. The main region and edge region of the sheet are then stretched separately in the width direction (coordinate axis y direction) of the sheet (wherein the structure of the insulating base layer is as follows Figure 6C, the ratio of the width W2 of the first main area to the width W1 of the first edge area and the width W3 of the second edge area is 7:1.5:1.5). For example, the stretching multiple of the main area of ​​the casting along the width direction is 1 times, and the edge area is stretched 2 times. After the stretching is completed, the insulating base layer is placed in a high-temperature shaping device at 130°C for 6 hours to fully remove the membrane stress, and the thickness of the insulating base layer is 8μm.

[0266] S200, preparing a conductive layer: After cleaning the above-prepared insulating base layer by acid washing, alkali washing, etc., the insulating base layer is placed in a vacuum evaporation chamber, a mask is placed at the edge of the insulating base layer, the aperture of the mask is 1 μm, and conductive metal copper is deposited on one side of the insulating base layer at a high temperature of 1300°C to 2000°C to form a copper conductive layer, and conductive metal aluminum is deposited on the other side of the insulating base layer to form an aluminum conductive layer. The thickness of the copper conductive layer and the aluminum conductive layer are respectively 10 μm, and the structures of the copper conductive layer and the aluminum conductive layer are as shown Figure 7B The orthographic projections of the second main areas of the copper conductive layer and the aluminum conductive layer on the organic layer completely overlap with the first main area of ​​the above-mentioned insulating base layer (the ratio of the width T2 of the second main area to the width T1 of the third edge area and the width T3 of the fourth edge area is 7:1.5:1.5). The edge areas of the copper conductive layer and the aluminum conductive layer are provided with through holes (with an average pore diameter of 1 μm), and no holes are provided in the main area of ​​the conductive layer.

[0267] Comparative Example Preparation Example 1

[0268] A method for preparing a current collector is provided. The method is different from the above-mentioned Preparation Example 1 in that no mask is provided in step S200, that is, no through-holes are formed on the conductive layer.

[0269] Comparative Example Preparation Example 2

[0270] A method for preparing a current collector is provided. The method for preparing a current collector is different from the above-mentioned Preparation Example 1 in that in step S100, the main area and the edge area of ​​the insulating base layer are not stretched in the width direction, and there are no through holes on the conductive layer.

[0271] Comparative Example Preparation Example 3

[0272] A method for preparing a current collector is provided. The method for preparing a current collector is different from the above-mentioned Preparation Example 1 in that in step S100, for example, the main area of ​​the casting along the width direction is stretched 2 times, and the edge area is stretched 1 times.

[0273] Preparation Example 2-1

[0274] A method for preparing a current collector is provided. The difference between the preparation method and the above-mentioned Preparation Example 1 is that in step S100, the stretching ratio of the main area of ​​the casting along the width direction is 2 times, and the stretching ratio of the edge area is 3 times. The rest remains the same as Preparation Example 1.

[0275] Preparation Example 2-2

[0276] A method for preparing a current collector is provided. The difference between the preparation method and the above-mentioned Preparation Example 1 is that in step S100, the stretching ratio of the main area of ​​the casting along the width direction is 1 times, and the stretching ratio of the edge area is 4 times. The rest remains the same as Preparation Example 1.

[0277] Preparation Example 2-3

[0278] A method for preparing a current collector is provided. The difference between the preparation method and the above-mentioned Preparation Example 1 is that in step S100, the stretching ratio of the main area of ​​the casting along the width direction is 1.8 times, and the stretching ratio of the edge area is 3.5 times. The rest remains the same as Preparation Example 1.

[0279] Preparation Example 3-1

[0280] A method for preparing a current collector is provided. The method is different from the above-mentioned Preparation Example 1 in that in step S200, through holes (with an average pore diameter of 100 nm) are provided in the edge region of the conductive layer.

[0281] Preparation Example 4-1

[0282] A method for preparing a current collector is provided. The method is different from the above-mentioned Preparation Example 1 in that in step S200, through holes (with an average pore diameter of 10 μm) are provided in the edge region of the conductive layer.

[0283] The pore size parameters and liquid absorption capacity of the current collectors prepared in the above preparation examples and comparative examples are tested as follows:

[0284] (1) Test the porosity of the insulation base layer:

[0285] The battery cells were placed in a 1.0 mol / L sodium hydroxide aqueous solution at room temperature for discharge treatment. After discharge, they were manually disassembled to obtain the pole pieces and separators. A cryo-focused ion beam (FIB) was used to finely slice the current collector of the pole piece layer by layer at different thickness positions (the smallest scale could reach nanoscale thin slices) to separate the insulating base layer and the conductive layer. Different area areas of the insulating base layer were then cut to obtain main area samples and edge area samples.

[0286] Cut each insulating base sample after drying into a square sample of about 20mm×20mm. Measure the thickness and actual side length with a digital micrometer and a vernier caliper, calculate its volume V, and weigh its weight M0. Then immerse the square sample in n-hexadecane reagent, soak it in air at room temperature for 2 hours, then take it out, absorb the n-hexadecane reagent liquid adsorbed on the surface, and then weigh its weight M0. t , then the porosity of each membrane layer satisfies the following mathematical relationship:

[0287] Porosity = (M t -M0) / ρ×V×100%;

[0288] The ρ in the above mathematical relationship is the density of the n-hexadecane reagent, in g / mm 3 , V is the volume of the square sample of each film layer, unit is mm 3 , weight M0 and M t The unit is g, and the weight measuring instrument is a thousandth balance.

[0289] (2) Test the average pore size of the holes in the insulating base layer and the through holes in the conductive layer:

[0290] The battery cells were placed in a 1.0 mol / L sodium hydroxide aqueous solution at room temperature for discharge treatment. After the discharge was completed, they were manually disassembled to obtain the pole pieces and separators. A cryo-focused ion beam (FIB) was used to finely slice the current collectors of the pole pieces layer by layer at different thickness positions (the smallest scale could reach nanoscale thin slices) to separate the insulating base layer and the conductive layer. Different area areas of the insulating base layer and the conductive layer were then cut to obtain main area samples and edge area samples.

[0291] The test instrument used is ASAP2460-physical adsorption analyzer. The dried and degassed samples are placed in liquid nitrogen. Different test pressures are adjusted to measure the adsorption amount of nitrogen. The adsorption and desorption isotherms are then plotted. The pore volume and specific surface area of ​​each sample are then obtained based on the adsorption and desorption isotherms, and the average pore size is then calculated.

[0292] (3) Test the saturated absorption rate of the current collector to the electrolyte:

[0293] Obtain the current collector according to the above method. First, weigh the mass of the composite current collector and record it as m0. Immerse the weighed composite current collector completely in the electrolyte for 2 hours. Then take it out and wipe off the residual electrolyte on the surface with dust-free paper. Weigh it again and record it as m1. Calculate the maximum liquid absorption rate of the composite current collector using the following formula:

[0294] θ=(m1-m0) / m0×100%;

[0295] In the above formula, θ is the liquid absorption rate, %.

[0296] The electrolyte of this application is the electrolyte used in Example 1.

[0297] Table 1 Parameters and performance list of current collector

[0298]

[0299] In combination with Preparation Example 1, Comparative Preparation Example 1, Preparation Example 3-1 and Preparation Example 4-1 in Table 1, it can be seen that the through holes and the pore size in the edge area of ​​the conductive layer have no effect on the saturated liquid absorption rate of the current collector. However, those skilled in the art know that in order to facilitate the flow of electrolyte absorbed by the current collector to the active material layer, through holes need to be opened on the conductive layer, but at the same time, attention should also be paid to the effect of the through holes on the conductivity of the current collector.

[0300] From the preparation example 1 and the comparative preparation example 2 in Table 1, it can be seen that the pore size and porosity of the insulating base layer affect the saturated liquid absorption capacity of the current collector for the electrolyte.

[0301] Example 1

[0302] A method for preparing a battery cell is provided, wherein the structure diagram of the electrode of the battery cell is as follows Figure 10 Indicate, combine Figure 10 It can be seen that the negative electrode active material layer 11 is provided on one surface of the current collector 4 , and the positive electrode active material layer 21 is provided on the other surface.

[0303] The preparation method of the battery cell includes the following preparation process:

[0304] Preparation of positive electrode sheet:

[0305] Take the ternary material LiNi 0.5 Co 0.3 Mn 0.2 O2 (NCM532), conductive carbon black, and PVDF were mixed in a ratio of 93:2:5, and nitrogen methyl pyrrolidone solvent was added and stirred to form a positive electrode slurry. The positive electrode slurry was coated on the surface of the aluminum metal layer of the positive electrode current collector prepared in the above preparation example 1. The coating shape was as follows: Figure 11 Schematically, a main positive electrode film layer and an edge positive electrode film layer are formed, and the coating thickness of the main positive electrode film layer is h1, and the coating thickness of the edge positive electrode film layer is h2, satisfying: h1 / h2=1.1;

[0306] Heating and drying, specifically using a multi-section oven with the temperature settings of 120℃ / 100℃ / 90℃, and then using a cold press to compact the positive electrode film to obtain a compaction density of 2.8g / cm 3 .

[0307] Preparation of negative electrode sheet:

[0308] Artificial graphite (median particle size Dv50 is 21.7 μm) and conductive agent conductive carbon black, stabilizer carboxymethyl cellulose and binder SBR are dispersed in deionized water in a mass ratio of 96.5:1.0:1.0:1.5 to form a negative electrode slurry. The negative electrode slurry is evenly coated on the surface of the copper conductive layer prepared in the above preparation example 1, wherein the coating shape is as follows: Figure 11 Schematically, a main negative electrode film layer and an edge negative electrode film layer are formed, and the coating thickness of the main negative electrode film layer is h1', and the coating thickness of the edge negative electrode film layer is h2', satisfying: h1' / h2'=1.05;

[0309] The temperature of the nine-stage drying oven was set at 100℃ / 100℃ / 95℃ / 85℃ / 85℃ / 80℃ / 80℃ / 80℃ / 60℃ for drying, and then a cold press was used for compaction. The compaction density of the negative electrode film was 1.65g / cm 3 .

[0310] Isolators available:

[0311] A porous polypropylene (PP) film was used as the separator, with a thickness of 10 μm and a porosity of 57.6%.

[0312] Provide electrolyte:

[0313] In an argon atmosphere glove box with a water content of <10ppm, EC (ethylene carbonate), PC (polycarbonate), and DMC (dimethyl carbonate) were mixed in a weight ratio of EC:PC:DMC=3:3:3, and then LiPF6, VC, DTD, and PS were added and stirred evenly to obtain an electrolyte, wherein the concentration of LiPF6 in the lithium-ion battery electrolyte was 1mol / L, and the mass percentages of VC, DTD, and PS were 3%, 1%, and 1%, respectively, to obtain an electrolyte.

[0314] Assembling battery cells:

[0315] The positive electrode sheets, separators, and negative electrode sheets are stacked in sequence, with the separators being placed between the positive and negative electrode sheets to serve as an isolation mechanism, and the cells are assembled to form wound bare cells. The wound bare cells are placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum packaging, standing, forming, and shaping processes, a battery cell is obtained.

[0316] Comparative Example 1

[0317] A method for preparing a battery cell is provided. Comparative Example 1 differs from Example 1 in that the current collector is replaced with the current collector of Comparative Preparation Example 1, and the rest remains the same as Example 1.

[0318] Comparative Example 2

[0319] A method for preparing a battery cell is provided. Comparative Example 1 differs from Example 1 in that the current collector is replaced with the current collector of Comparative Preparation Example 2, and the rest remains the same as Example 1.

[0320] Comparative Example 3

[0321] A method for preparing a battery cell is provided. Comparative Example 1 differs from Example 1 in that the current collector is replaced with the current collector of Comparative Preparation Example 3, and the rest remains the same as Example 1.

[0322] Example 2-1

[0323] A method for preparing a battery cell is provided. The difference between Example 2-1 and Example 1 is that the current collector is replaced with the current collector of Preparation Example 2-1, and the other steps are the same as Example 1.

[0324] Example 2-2

[0325] A method for preparing a battery cell is provided. Example 2-2 differs from Example 1 in that the current collector is replaced with the current collector of Preparation Example 2-2, and the rest remains the same as Example 1.

[0326] Example 2-3

[0327] A method for preparing a battery cell is provided. The difference between Example 2-3 and Example 1 is that the current collector is replaced with the current collector of Preparation Example 2-3, and the other steps are the same as Example 1.

[0328] Example 3-1

[0329] A method for preparing a battery cell is provided. The difference between Example 3-1 and Example 1 is that the current collector is replaced with the current collector of Preparation Example 3-1, and the other steps are the same as those of Example 1.

[0330] Example 4-1

[0331] A method for preparing a battery cell is provided. The difference between Example 4-1 and Example 1 is that the current collector is replaced with the current collector of Preparation Example 4-1, and the other steps are the same as Example 1.

[0332] Example 5-1

[0333] A method for preparing a battery cell is provided. The difference between Example 5-1 and Example 1 is that the negative electrode film layer is formed according to Figure 9BSchematic diagram, wherein the particle size Dv50 of the first graphite in the first negative electrode active material layer arranged close to the current collector is 6.5 μm, the particle size Dv50 of the second graphite in the second negative electrode active material layer arranged away from the current collector is 21.7 μm, the thickness of the first negative electrode active material layer is consistent with the thickness of the second negative electrode active material layer, and the others remain the same as in Example 1, and the difference between the first graphite and the second graphite is only the particle size, and the others remain the same.

[0334] Example 6-1

[0335] A method for preparing a battery cell is provided. Example 6-1 differs from Example 1 in that the isolation member of the battery cell includes: a porous polyethylene (PE) film with a thickness of 13 μm is used as a base film (porosity of 57.6%), and an organic polymer coating (PE) is formed on both sides of the base film. The edge area porosity of the organic polymer coating is 65.3%, and the main area porosity of the organic polymer coating is 57.7%; the orthographic projection of the edge area of ​​the positive electrode active material layer on the above-mentioned coating completely overlaps with the edge area of ​​the coating, and other aspects remain the same as Example 1-1.

[0336] Example 7-1

[0337] A method for preparing a battery cell is provided. The difference between Example 7-1 and Example 1 is that the edges of the positive electrode active material layer and the negative electrode active material layer are not thinned, and other aspects remain the same as Example 1-1.

[0338] The batteries prepared in the above examples and comparative examples of this application were cycled for 500 cycles at 25°C to calculate the capacity retention rate. The batteries were also disassembled to further observe the lithium deposition on the negative electrode surface. The specific test methods and results are as follows:

[0339] (4) Test the capacity retention of the battery after 500 cycles at 25°C:

[0340] Under a constant temperature environment of 25℃, the battery was charged to 4.4V at a constant current of 1C, then charged at a constant voltage of 4.4V until the current dropped to 0.05C, and then discharged to 2.5V at a constant current of 1C to obtain the first cycle discharge capacity (Cd1); this charge and discharge were repeated until the 500th cycle, and the discharge capacity after 500 cycles was recorded as Cdn.

[0341] Capacity retention (%) = discharge capacity after 500 cycles (Cdn) / discharge capacity in the first cycle (Cd1)

[0342] (5) Determination and analysis of lithium deposition on the edge of the negative electrode after the battery has been cycled 500 times at 25°C:

[0343] After the battery was cycled 500 times according to the above-mentioned cycling method, it was charged to 4.3V at a constant current of 0.33C, and then charged at a constant voltage of 4.3V until the current dropped to 0.05C. The battery was then disassembled, and the positive and negative electrodes were further separated. A scanning electron microscope was used to observe the lithium deposition on the surface of the negative electrode, especially the lithium deposition on the edge area of ​​the negative electrode.

[0344] The criteria for determining lithium deposition are shown in the following table;

[0345] Table 2 Determination level of lithium deposition on the surface of negative electrode

[0346]

[0347] The performance test results of the batteries prepared in the above examples and comparative examples are shown in Table 3 below.

[0348] Table 3 Battery performance list

[0349]

[0350]

[0351] From Example 1, Comparative Examples 2 and 3 in Table 3, it can be seen that the present application adopts a design in which the porosity of the main area of ​​the insulating base layer is greater than the porosity of the edge area of ​​the insulating base layer, which is beneficial to better reduce lithium plating and improve the cycle life of the battery.

[0352] Further comparison of Example 1, Example 2-1 and Example 2-3 shows that the main area and edge area of ​​the insulating base layer have appropriate porosity and a certain appropriate width, which is beneficial to improving the cycle life of the battery.

[0353] Combining Example 1, Comparative Example 1 and Comparative Example 2 in Table 3, it can be seen that in order to facilitate the flow of electrolyte absorbed by the current collector to the active material layer, through holes need to be opened on the conductive layer. Further combining Example 3-1 and Example 4-1, it can be seen that the average pore size of the through holes needs to be set within an appropriate range.

[0354] From the combination of Example 1 and Example 5-1 in Table 3, it can be seen that the present application adopts a design method of matching the current collector and the active material layer, which is conducive to further improving the cycle life of the battery.

[0355] Combining Example 1 and Example 7-1 in Table 3, it can be seen that the current collector provided in the present application conveniently solves the problem that the edge of the active material layer is not easily wetted by the electrolyte after the edge is thinned.

[0356] In summary, the design approach provided in this application is beneficial for improving the cycle life of the battery by increasing the wettability of the electrolyte to the electrode.

[0357] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: The present invention comprises a current collector and an active material layer located on at least one side of the current collector; the current collector comprises an insulating base layer, the insulating base layer comprises a first main region and an edge region located outside the first main region; the porosity of the first main region of the insulating base layer is less than the porosity of the edge region of the insulating base layer; the porosity of the edge region of the insulating base layer is 10% to 40%; The current collector further includes a conductive layer, wherein the conductive layer is located between the insulating base layer and the active material layer; The conductive layer includes a second main region and an edge region located outside the second main region; the edge region of the conductive layer is provided with a through hole; the second main region of the conductive layer is not provided with a hole; An orthographic projection of an edge region of the conductive layer on the insulating base layer at least partially overlaps with an edge region of the insulating base layer.

2. The battery cell according to claim 1, wherein: The porosity of the first main region of the insulating base layer is 0-20%.

3. The battery cell according to any one of claims 1 to 2, characterized in that: The first main region of the insulating base layer comprises a porous structure, and the average pore size of the porous structure is 10 nm to 10 μm; and / or; The edge area of ​​the insulating base layer comprises a porous structure, and the average pore diameter of the porous structure is 10 nm to 10 μm.

4. The battery cell according to claim 3, wherein: The insulating base layer includes a first edge region and a second edge region, the first edge region and the second edge region extend along a first direction and are arranged in a second direction, and the first main region is provided between the first edge region and the second edge region; The first direction intersects the second direction; The first main body region comprises a porous structure, and the average pore size of the porous structure is 50 nm to 2 μm; and / or; The first edge region and the second edge region include a porous structure, and the average pore size of the porous structure of the first edge region and the average pore size of the porous structure of the second edge region are independently selected from 500 nm to 4 μm.

5. The battery cell according to claim 4, characterized in that: Along the second direction, the first edge region includes a surface A and a surface B that are opposite to each other, and a distance between the surface A and the surface B is W1; Along the second direction, the first main body region includes a C surface and a D surface that are opposite to each other, and a distance between the C surface and the D surface is W2; Along the second direction, the second edge region includes an A' surface and a B' surface that are opposite to each other, and a distance between the A' surface and the B' surface is W3; Satisfies: W2:W1:W3=6~8:1~2:1~2.

6. The battery cell according to any one of claims 1 to 2, characterized in that: The average pore diameter of the through holes in the edge area of ​​the conductive layer is 100 nm to 10 μm.

7. The battery cell according to any one of claims 1 to 2, characterized in that: The conductive layer includes a third edge region and a fourth edge region, the third edge region and the fourth edge region extend along the first direction and are arranged in the second direction, and the second main region is provided between the third edge region and the fourth edge region; The first direction intersects the second direction; The second main body region of the conductive layer is not provided with a hole; The third edge region and the fourth edge region of the conductive layer are provided with through holes, and the average pore diameter of the through holes in the third edge region and the average pore diameter of the through holes in the fourth edge region are independently selected from 200 nm to 5 μm.

8. The battery cell according to claim 7, characterized in that: Along the second direction, the third edge region includes an E surface and an F surface that are opposite to each other, and a distance between the E surface and the F surface is T1; Along the second direction, the second main body region includes a G surface and an H surface arranged opposite to each other, and a distance between the G surface and the H surface is T2; Along the second direction, the fourth edge region includes an E' surface and an F' surface that are opposite to each other, and a distance between the E' surface and the F' surface is T3; Satisfies: T2:T1:T3=6~8:1~2:1~2.

9. The battery cell according to any one of claims 1 to 2, characterized in that: The material of the insulating base layer includes any one or more of epoxy resin, polyamide, polyester, polyolefin, polyacetylene, siloxane polymer, polyether, polyol, polysaccharide polymer, amino acid polymer, polysulfur nitride polymer, and aromatic ring polymer; and / or; The conductive layer includes metal, and the metal includes any one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, iron alloy, titanium, titanium alloy, silver and silver alloy.

10. The battery cell according to claim 9, characterized in that: The polyester comprises polyethylene terephthalate; and / or; The polyolefin includes any one or more of polyethylene and polypropylene; and / or; The aromatic ring polymer includes any one or more of polysulfone and polyimide.

11. The battery cell according to any one of claims 1 to 2, characterized in that: The insulating base layer and the conductive layer extend along a first direction and are stacked in a third direction; The first direction intersects the third direction; Along the third direction, the thickness of the insulating base layer is 25 μm to 50 μm; and / or; Along the third direction, the thickness of the conductive layer is 3 μm to 10 μm.

12. The battery cell according to any one of claims 1 to 2, characterized in that: The current collector and the active material layer extend along a first direction and are stacked in a third direction; The first direction intersects the third direction; Along the third direction, the active material layer includes an M surface and an N surface arranged opposite to each other, the M surface is arranged close to the current collector, and the distance between the M surface and the N surface is H; The area extending from the M surface to the position 0.1×H is recorded as the first area, and the area extending from the N surface to the position 0.1×H is recorded as the second area; The first region includes a first active material, and the second region includes a second active material; The median particle size of the first active material is smaller than the median particle size of the second active material.

13. The battery cell according to any one of claims 1 to 2, characterized in that: The current collector and the active material layer extend along a first direction and are stacked in a third direction; The first direction intersects the third direction; Along the third direction, the active material layer includes a first active material layer disposed close to the current collector and a second active material layer located on a surface of the first active material layer away from the current collector; The first active material layer includes a first active material, and the second active material layer includes a second active material; The median particle size of the first active material is smaller than the median particle size of the second active material.

14. The battery cell according to any one of claims 1 to 2, characterized in that: The current collector and the active material layer extend along a first direction and are stacked in a third direction; the first direction intersects the third direction; The active material layer includes an active material main body region and an edge thinning region located outside the active material main body region; An orthographic projection of the edge thinning region on the current collector at least partially overlaps with an edge region of the conductive layer.

15. The battery cell according to any one of claims 1 to 2, characterized in that: The battery cell includes a separator, wherein the separator includes a third main body region and an edge region located outside the third main body region; The orthographic projection of the edge region of the isolating element on the conductive layer at least partially overlaps with the edge region of the conductive layer; The porosity of the edge area of ​​the separator is 70% to 80%.

16. A current collector, characterized in that: Including insulating base; The insulating base layer includes a first main region and an edge region located outside the first main region; the porosity of the first main region of the insulating base layer is smaller than the porosity of the edge region of the insulating base layer; the porosity of the edge region of the insulating base layer is 10% to 40%; The current collector further includes a conductive layer, wherein the conductive layer is located between the insulating base layer and the active material layer; The conductive layer includes a second main area and an edge area outside the second main area; the edge area is provided with a through hole; the orthographic projection of the edge area of ​​the conductive layer on the insulating base layer at least partially overlaps with the edge area of ​​the insulating base layer.

17. A battery device, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 15 or the current collector according to claim 16.

18. An electrical device, characterized in that: A battery device comprising the battery device of claim 17.

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