Electrode assembly, battery cell, preparation method, battery apparatus, and electric apparatus

Abstract

Provided in the present application are an electrode assembly, a battery cell, a preparation method, a battery apparatus, and an electric apparatus. The preparation method for a battery cell comprises: providing an electrode assembly to be pressed, wherein at least one side of said electrode assembly in the thickness direction thereof is an outermost active material layer; bonding an adhesive layer on the outermost active material layer to form an intermediate assembly; pressing the intermediate assembly to obtain a pressed assembly, wherein the density of the pressed assembly meets a first preset density; removing the adhesive layer and the outermost active material layer of the pressed assembly to form an electrode assembly; and assembling the electrode assembly into a housing to prepare a battery cell. The energy density of battery cells can be increased.

Description

Electrode assembly, battery cell, manufacturing method, battery device, and electric device

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202411116510.5, filed on August 14, 2024, entitled “Electrode assembly, battery cell, manufacturing method, battery device, and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of battery devices, in particular to an electrode assembly, a battery cell, a manufacturing method, a battery device, and an electric device. BACKGROUND

[0004] Battery cells have characteristics such as high capacity and long service life, and are therefore widely used in electronic devices such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, and electric tools.

[0005] As the application range of battery cells becomes more and more extensive, the requirements for battery performance are gradually increasing, for example, the requirement for the energy density of battery cells is gradually increasing. SUMMARY

[0006] The present application is made in view of the above-mentioned problems, and aims to provide an electrode assembly, a battery cell, a manufacturing method, a battery device, and an electric device, which can improve the energy density of the battery cell.

[0007] In a first aspect, the present application provides a manufacturing method of a battery cell, the manufacturing method comprising: providing a to-be-pressed electrode assembly, the to-be-pressed electrode assembly having an outermost active material layer on at least one side along the thickness direction of the to-be-pressed electrode assembly; adhering an adhesive layer to the outermost active material layer to form an intermediate assembly; pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density; removing the adhesive layer and the outermost active material layer of the pressed assembly to form an electrode assembly; and assembling the electrode assembly into a shell to obtain the battery cell.

[0008] Thus, the present application can improve the occupied space of the active material layer that can participate in charging and discharging by removing the invalid active material layer on the outermost side of the to-be-pressed electrode assembly, thereby improving the energy density of the battery cell.

[0009] In some embodiments, the step of densifying the intermediate assembly to a density satisfying the first preset density comprises: pre-pressing the intermediate assembly to a density satisfying a second preset density; and re-pressing the intermediate assembly to obtain the pressed assembly, the density of the pressed assembly satisfying the first preset density, the first preset density being greater than the second preset density.

[0010] In this way, the density of the electrode assembly can be improved by multiple pressing processes, and the energy density of the battery cell can be improved.

[0011] In some embodiments, the second preset density is 60% to 85%. In this way, the density after pre-pressing is relatively high, the density of the electrode assembly can be improved, and the energy density of the battery cell can be improved.

[0012] In some embodiments, the step of densifying the intermediate assembly to a density satisfying the second preset density comprises: flat pressing the intermediate assembly to a density satisfying the second preset density.

[0013] In some embodiments, the flat pressing temperature is 25°C to 200°C. By pressing under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0014] In some embodiments, the flat pressing pressure is 3MPa to 20MPa. By pressing under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0015] In some embodiments, the flat pressing time is 10s to 180s. By pressing under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0016] In some embodiments, the first preset density is greater than or equal to 94.0% and less than 100%, and can be 94.0% to 97.5%. In this way, the density after pressing is relatively high, the density of the electrode assembly can be improved, and the energy density of the battery cell can be improved.

[0017] In some embodiments, the step of densifying the intermediate assembly to a density satisfying the first preset density comprises: isostatic pressing the intermediate assembly to obtain the pressed assembly, the density of the pressed assembly satisfying the first preset density.

[0018] In some embodiments, the step of obtaining the compacted assembly by isostatic pressing the intermediate assembly to obtain a compacted assembly with a density satisfying the first preset density includes: providing a packaging film to the intermediate assembly to wrap the intermediate assembly to form a to-be-isostatic-pressed assembly; extracting gas in the to-be-isostatic-pressed assembly until a vacuum degree in the to-be-isostatic-pressed assembly satisfies a preset vacuum degree; sealing the to-be-isostatic-pressed assembly, and then performing isostatic pressing on the to-be-isostatic-pressed assembly to obtain the compacted assembly with the density satisfying the first preset density; and removing the packaging film of the compacted assembly.

[0019] In some embodiments, the tensile strength of the packaging film is 20 N to 85 N. When the tensile strength of the packaging film is in the above range, after the sealing treatment, there may still be some space in the to-be-isostatic-pressed assembly, which can provide a gas storage space for the extruded gas in the isostatic pressing process, and is conducive to further improving the density.

[0020] In some embodiments, the material of the packaging film includes one or more of polyolefin, polyimide, metal, and polyphenylene sulfide. The above materials can effectively seal the to-be-isostatic-pressed assembly.

[0021] In some embodiments, the polyolefin material includes one or more of polyethylene, polypropylene, and polytetrafluoroethylene.

[0022] In some embodiments, the polyimide material includes one or more of polyimide, polyimide ether ketone, polyether imide, and polyimide ether sulfone.

[0023] In some embodiments, the metal material includes one or more of aluminum, copper, and steel.

[0024] In some embodiments, the preset vacuum degree is -100 KPa to -50 KPa. By performing the pressing treatment under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0025] In some embodiments, the temperature of the isostatic pressing is 0°C to 250°C. By performing the pressing treatment under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0026] In some embodiments, the pressure of the isostatic pressing is 100 MPa to 2000 MPa. By performing the pressing treatment under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0027] In some embodiments, the time of the isostatic pressing is 1 min to 90 min. By performing the pressing treatment under the above conditions, the density of the electrode assembly can be effectively improved, and the energy density of the battery cell can be improved.

[0028] In some embodiments, the peeling strength of the adhesive layer is 1 N / m to 80 N / m; the adhesive layer is a film layer with a certain viscosity, so that the adhesive layer can be bonded with the outermost active material layer.

[0029] In some embodiments, the shrinkage of the adhesive layer is 2.4% to 11.5%. When the shrinkage of the adhesive layer is in the above range, the shrinkage ability is relatively strong, and the shrinkage range is relatively large during the pressing process, which is more conducive to driving the outermost active material layer to peel off.

[0030] In some embodiments, the adhesive layer comprises one or more of polyolefin, polyimide, polyether, polylactic acid, polyacrylate, polyurethane, and ethylene-vinyl acetate copolymer.

[0031] In some embodiments, the polyolefin comprises one or more of polyethylene, polypropylene, and polytetrafluoroethylene; the above-mentioned materials can effectively bond the outermost active material layer.

[0032] In some embodiments, the polyimide comprises one or more of polyimide, polyimide ether ketone, polyether imide, and polyimide ether sulfone.

[0033] In some embodiments, the polyether comprises one or more of polyvinyl ether and polyphenylene sulfide.

[0034] In some embodiments, the step of providing the electrode assembly to be pressed, at least one side of the electrode assembly along the thickness direction thereof is the outermost active material layer, comprises the following steps: providing a plurality of first electrode sheets, the first electrode sheet comprising a first current collector and a first active material layer, the first active material layer being arranged on both sides of the first current collector along the thickness direction; providing a plurality of second electrode sheets, the second electrode sheet comprising a second current collector and a second active material layer, the second active material layer being arranged on both sides of the second current collector along the thickness direction, the polarity of the second electrode sheet being opposite to that of the first electrode sheet; providing a plurality of solid electrolyte layers; and alternately stacking the first electrode sheet, the solid electrolyte layer, and the second electrode sheet along the thickness direction to obtain the electrode assembly to be pressed, wherein the first electrode sheet is located at the outermost side of the electrode assembly along the thickness direction, and the outermost active material layer is the first active material layer; or the second electrode sheet is located at the outermost side of the electrode assembly along the thickness direction, and the outermost active material layer is the second active material layer.

[0035] In some embodiments, the projection of the first current collector along the thickness direction has a rectangular profile. In this way, the energy density of the battery cell can be further improved.

[0036] In some embodiments, the projection of the second current collector along the thickness direction has a rectangular profile. In this way, the energy density of the battery cell can be further improved.

[0037] In some embodiments, the outermost active material layer comprises a positive active material; or the outermost active material layer comprises a negative active material.

[0038] In some embodiments, the electrode assembly to be pressed has the outermost active material layer on both sides in the thickness direction.

[0039] In some embodiments, the electrode assembly to be pressed has the outermost active material layer on both sides in the thickness direction.

[0040] In some embodiments, the electrode assembly to be pressed has the outermost active material layer on both sides in the thickness direction.

[0041] In some embodiments, the electrode assembly to be pressed has the outermost active material layer on both sides in the thickness direction.

[0042] In some embodiments, the plurality of electrode tabs comprises a plurality of first tabs and a plurality of second tabs, the first tab comprises a first current collector and a first active material layer, the first active material layer is disposed on at least one side of the first current collector in the thickness direction; the second tab comprises a second current collector and a second active material layer, the second active material layer is disposed on at least one side of the second current collector in the thickness direction, the first tab and the second tab have opposite polarities, wherein the plurality of first tabs and the plurality of second tabs are stacked in the thickness direction, at least one side of the electrode assembly in the thickness direction is the first current collector; or at least one side of the electrode assembly in the thickness direction is the second current collector. Thus, the energy density of the battery cell can be improved.

[0043] In some embodiments, the electrode assembly to be pressed has the outermost active material layer on both sides in the thickness direction.

[0044] In some embodiments, the electrode assembly to be pressed has the outermost active material layer on both sides in the thickness direction.

[0045] In some embodiments, the projection of the current collector in the thickness direction is rectangular. The area of the current collector carrying the active material layer is increased, which is beneficial to improve the energy density of the battery cell.

[0046] In a third aspect, the embodiments of the present application provide a preparation method of an electrode assembly. The preparation method comprises: providing a to-be-pressed electrode assembly, the to-be-pressed electrode assembly being provided with an outermost active material layer on at least one side in a thickness direction of the to-be-pressed electrode assembly; adhering an adhesive layer to the outermost active material layer to form an intermediate assembly; performing a pressing process on the intermediate assembly to obtain a pressed assembly, the pressed assembly having a first preset density; and removing the adhesive layer and the outermost active material layer of the pressed assembly to form the electrode assembly.

[0047] In a fourth aspect, the embodiments of the present application provide an electrode assembly. The electrode assembly comprises a plurality of electrode sheets and a solid-state electrolyte layer, the plurality of electrode sheets being stacked along a thickness direction of the electrode assembly, and the solid-state electrolyte layer being located between two adjacent electrode sheets. Each electrode sheet comprises a current collector and an active material layer located on at least one side of the current collector. At least one side of the electrode assembly in the thickness direction is the current collector.

[0048] Therefore, when at least one side of the electrode assembly in the thickness direction is the current collector, the electrode assembly does not include an invalid active material layer that cannot participate in charging and discharging on both sides, so that the occupied space of the active material layer that can participate in charging and discharging is increased, and the energy density of the battery cell is improved.

[0049] In a fifth aspect, the embodiments of the present application provide a battery device comprising the battery cell according to any one of the embodiments of the first aspect of the present application or prepared by the preparation method according to any one of the embodiments of the second aspect of the present application.

[0050] In a sixth aspect, the embodiments of the present application provide an electric device comprising the battery device according to the fifth aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0052] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0053] FIG. 2 is an exploded schematic diagram of a battery pack according to some embodiments of the present application;

[0054] FIG. 3 is a structural schematic diagram of a battery module according to some embodiments of the present application;

[0055] FIG. 4 is a structural schematic diagram of a battery cell according to some embodiments of the present application;

[0056] FIG. 5 is a structural diagram of an electrode assembly in a battery cell according to some embodiments of the present application;

[0057] FIG. 6 is a structural diagram of an electrode assembly in a battery cell according to other embodiments of the present application;

[0058] FIG. 7 is a structural diagram of a first electrode tab in a battery cell according to other embodiments of the present application;

[0059] FIG. 8 is a flowchart of a method of manufacturing an electrode assembly according to other embodiments of the present application;

[0060] FIG. 9 is a structural diagram of a to-be-pressed electrode assembly according to some embodiments of the present application;

[0061] FIG. 10 is a structural diagram of a to-be-pressed electrode assembly and an adhesive layer according to some embodiments of the present application;

[0062] FIG. 11 is a structural diagram of a to-be-pressed electrode assembly in a pressing process according to some embodiments of the present application;

[0063] FIG. 12 is a structural diagram of a packaging film according to some embodiments of the present application;

[0064] FIG. 13 is a flowchart of a method of manufacturing a battery cell according to other embodiments of the present application;

[0065] The accompanying drawings are not necessarily drawn to scale.

[0066] The reference signs are explained as follows: X, thickness direction; 1, vehicle; 2, battery pack; 3, controller; 4, motor; 5, case; 5a, first case portion; 5b, second case portion; 5c, accommodation space; 6, battery module; 7, battery cell; 10, electrode assembly; 20, housing; 30, first electrode tab; 31, first current collector; 32, first active material layer; 40, second electrode tab; 41, second current collector; 42, second active material layer; 50, solid electrolyte layer; 60, adhesive layer; 70, packaging film; 71, packaging cavity; 72, packaging cover. DETAILED DESCRIPTION

[0067] Hereinafter, embodiments of the electrode assembly, the battery cell, the manufacturing method, the battery device, and the power-using device according to the present application are specifically disclosed. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of matters that are already well known, repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0068] The ranges disclosed herein are intended to include both endpoints and intervening ranges unless the context clearly indicates otherwise. For example, a range of "60-120" is intended to include 60 and 120, as well as any intervening ranges, e.g., 66-110, 77- 104, etc. In other words, a range of "a-b" is a shorthand way of describing each and every number that is between (and including) the two endpoints of that range. This is because the endpoints of a range are always included as if they were repeated to infinity. Therefore, a range of 0-5 is intended to cover the numbers 0, 1, 2, 3, 4, and 5, inclusive of all numbers from 0 and 5. Likewise, a range of 1-5 is intended to cover the numbers 1, 2, 3, 4, and 5, inclusive of all numbers from 1 and 5. Also, it is specifically intended that the description set forth herein applies regardless of the number of digits in the range. For example, a range of 0.1- 5 is merely a shorthand way of stating each number that is between (and including) the two endpoints of that range, i.e., the range between 0.1 and 5, inclusive of any numbers with the digit "1" in the tenths place, and the number 5. Therefore, even if this

[0069] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0070] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0071] All steps of the present application can be performed in sequence or randomly, preferably in sequence, if not specifically stated otherwise. For example, a method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), which means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0072] Reference to "an embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to one alternative embodiment versus another alternative embodiment.

[0073] In the description of the present application, it should be noted that unless specifically stated and limited otherwise, the terms "mounting", "connected", "connection", "attached" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0074] The term "and / or" in the present application is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents that the front and rear associated objects have an "or" relationship.

[0075] In the embodiments of the present application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length, width and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0076] "Multiple" appearing in the present application means two or more (including two). In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging.

[0077] In the present application, the battery cell can include a lithium ion secondary battery cell, a lithium ion primary battery cell, a lithium-sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, a magnesium ion battery cell, a lithium metal battery cell, a sodium metal battery, etc. The embodiments of the present application are not limited thereto. The battery cell can be in the shape of a cylinder, a flat body, a cuboid or other shapes, etc. The embodiments of the present application are not limited thereto. The battery cell is generally divided into three types according to the packaging method: cylindrical battery cell, square battery cell and soft pack battery cell, and the embodiments of the present application are not limited thereto.

[0078] The battery device referred to in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery device referred to in the present application can include a battery module or a battery pack, etc. The battery device generally includes a box for packaging one or more battery cells. The box can prevent liquids or other foreign matters from affecting the charging or discharging of the battery cell.

[0079] With the development of the field of battery devices, the performance requirements for battery cells are gradually increasing, for example, the energy density requirements for battery cells are increasing.

[0080] The active material layer at the outermost side of the electrode assembly along the thickness direction thereof does not participate in charging and discharging. The embodiments of the present application improve the mass or volume of the active material layer inside the battery monomer that can participate in charging and discharging by removing the active material layer at the outermost side of the electrode assembly, and can effectively improve the energy density of the battery monomer.

[0081] The battery monomer described in the embodiments of the present application is suitable for a battery device and a power consumption device using the battery device.

[0082] The power consumption device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, and the like. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, and the like. The electric toy includes a fixed or mobile electric toy, for example, a game machine, an electric automobile toy, an electric ship toy, an electric airplane toy, and the like. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, and the like. The embodiments of the present application do not specially limit the above power consumption devices.

[0083] The following embodiments take the power consumption device as a vehicle for example for convenience of description.

[0084] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application.

[0085] As shown in FIG. 1, the vehicle 1 is internally provided with a battery pack 2, which can be arranged at the bottom, the head, or the tail of the vehicle 1. The battery pack 2 can be used for power supply of the vehicle 1, for example, the battery pack 2 can be used as an operating power source of the vehicle 1.

[0086] The vehicle 1 can further include a controller 3 and a motor 4, and the controller 3 is used to control the battery pack 2 to supply power to the motor 4, for example, to meet the working power demand of the vehicle 1 during starting, navigation, and driving.

[0087] In some embodiments of the present application, the battery pack 2 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0088] FIG. 2 is an exploded schematic diagram of a battery pack provided by some embodiments of the present application. As shown in FIG. 2, the battery pack 2 includes a box body 5 and a battery monomer (not shown in FIG. 2), and the battery monomer is accommodated in the box body 5.

[0089] The box 5 is used to accommodate the battery cells, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box part 5a and a second box part 5b, the first box part 5a and the second box part 5b are mutually covered, and the first box part 5a and the second box part 5b jointly define an accommodation space 5c for accommodating the battery cells. The second box part 5b can be a hollow structure with one end open, and the first box part 5a is a plate-shaped structure, the first box part 5a covers the open side of the second box part 5b to form the box 5 with the accommodation space 5c; or the first box part 5a and the second box part 5b can both be a hollow structure with one side open, and the open side of the first box part 5a covers the open side of the second box part 5b to form the box 5 with the accommodation space 5c. Of course, the first box part 5a and the second box part 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0090] To improve the sealing performance of the first box part 5a and the second box part 5b after being connected, a sealing member such as sealing glue, a sealing ring, etc. can be arranged between the first box part 5a and the second box part 5b.

[0091] Suppose the first box part 5a covers the top of the second box part 5b, the first box part 5a can also be called an upper box cover, and the second box part 5b can also be called a lower box.

[0092] In the battery pack 2, the battery cells can be one or multiple. If the battery cells are multiple, the multiple battery cells can be connected in series, in parallel, or in a mixed manner, and the mixed manner means that the multiple battery cells are connected in series and in parallel. The multiple battery cells can be directly connected in series, in parallel, or in a mixed manner, and then the whole of the multiple battery cells is accommodated in the box 5; of course, the multiple battery cells can be first connected in series, in parallel, or in a mixed manner to form a battery module 6, and then the multiple battery modules 6 are connected in series, in parallel, or in a mixed manner to form a whole and are accommodated in the box 5.

[0093] The battery cell can be the smallest unit constituting the battery device.

[0094] FIG. 3 is a structural schematic diagram of the battery module shown in FIG. 2.

[0095] In some embodiments, as shown in FIG. 3, the battery cells 7 are multiple, and the multiple battery cells 7 are first connected in series, in parallel, or in a mixed manner to form a battery module 6. Then the multiple battery modules 6 are connected in series, in parallel, or in a mixed manner to form a whole and are accommodated in the box.

[0096] The multiple battery cells 7 in the battery module 6 can be electrically connected through a busbar component to realize the parallel connection, the series connection, or the mixed connection of the multiple battery cells 7 in the battery module 6. The busbar component can be one or multiple, and each busbar component is used to electrically connect at least two battery cells 7.

[0097] FIG. 4 is a structural schematic diagram of a battery cell 7 according to some embodiments of the present application, and FIG. 5 is a structural schematic diagram of an electrode assembly 10 of the battery cell 7 according to some embodiments of the present application.

[0098] As shown in FIGS. 4 and 5, in some embodiments, the battery cell 7 includes the electrode assembly 10 and the housing 20, and the electrode assembly 10 is accommodated in the housing 20.

[0099] The housing 20 can have various shapes, such as a cylinder, a cuboid, etc. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, the housing 20 can also have a cylindrical structure. If the electrode assembly 10 has a cuboid structure, the housing 20 can also have a cuboid structure.

[0100] The material of the housing 20 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not make special limitations thereon. Optionally, the inner wall of the housing 20 can further include an insulating layer, which can separate the housing 20 and the electrode assembly 10. The material of the insulating layer can be selected from the commonly used materials in the art, and the present application does not make special limitations thereon.

[0101] The electrode assembly 10 accommodated in the housing 20 can be one or more.

[0102] From the appearance of the electrode assembly 10, the electrode assembly 10 includes a tab portion and a main body portion, the tab portion includes a first tab and a second tab, the polarities of the first tab and the second tab are opposite, and the first tab and the second tab respectively protrude from the main body portion. The first tab is a portion of the first tab plate without the active material layer, and the second tab is a portion of the second tab plate without the active material layer. The first tab and the second tab are used to lead out the current in the main body portion. The polarities of the first tab plate and the second tab plate are opposite, in other words, one of the first tab plate and the second tab plate is a positive tab plate, and the other of the first tab plate and the second tab plate is a negative tab plate.

[0103] The positive tab and the negative tab can be led out from the same end of the main body portion, or the positive tab and the negative tab can be led out from opposite ends of the main body portion, respectively.

[0104] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell 7, active ions (such as lithium ions) are inserted and extracted between the positive electrode and the negative electrode. Optionally, the electrode assembly 10 further includes a separator disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive electrode and the negative electrode, and at the same time, allow the active ions to pass through.

[0105] In some embodiments, the positive electrode can be a positive tab plate, and the positive tab plate can include a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, and the positive active material layer includes a positive active material.

[0106] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode active material layer is provided on either one or both of the two surfaces of the positive electrode current collector.

[0107] As an example, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, titanium, silver surface-treated aluminum, or stainless steel, or the like can be employed. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, or the like) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0108] As an example, when the battery cell 7 of the embodiment of the present application is a lithium ion battery, the positive electrode active material can include one or more of the following materials: phosphate, layered transition metal oxide, and a modified compound of each thereof; optionally, the positive electrode active material can include layered transition metal oxide and a modified compound of each thereof, which is advantageous in improving the energy density of the battery cell 7. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material layer can also be used. These positive electrode active materials can be used alone or in combination with two or more.

[0109] Examples of the phosphate can include, but are not limited to, one or more of lithium iron phosphate (such as LiFePO4 (which can also be referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0110] The layered transition metal oxide includes one or more of a compound of the general formula Li a Ni b Co c M d O e A f and a modified compound thereof, 0.8≤a≤1.2, 0.3≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes one or more of N, F, S, and Cl.

[0111] Examples of layered transition metal oxides can include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also can be referred to simply as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to simply as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to simply as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to simply as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to simply as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2), and modified compounds thereof, etc.

[0112] When the battery cell 7 of the embodiments of the present application is a sodium-ion battery or a sodium-metal battery, the positive electrode active material can include, but is not limited to, one or more of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), Prussian blue type materials.

[0113] As an example, the positive electrode active material for a sodium-ion battery can include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue type materials, X p M’ q (PO4) r Ox Y 3-x one or more of Li, Na, K, and NH4, M' is a transition metal cation, optionally one or more of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, Y is a halide anion, optionally one or more of F, Cl, and Br. p M' q (PO4) r O x Y 3-x one or more of Li, Na, K, and NH4, M' is a transition metal cation, optionally one or more of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, Y is a halide anion, optionally one or more of F, Cl, and Br. + 、Li + 、Na + 、K + and NH4 + one or more of Li, Na, K, and NH4, M' is a transition metal cation, optionally one or more of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, Y is a halide anion, optionally one or more of F, Cl, and Br.

[0114] In the embodiments of the present application, the modification compound of each of the above-mentioned positive electrode active materials can be a doping modification and / or a surface coating modification, for example, a carbon coating modification, a fast ion conductor coating modification, etc.

[0115] The battery cell 7 will be accompanied by the deintercalation and consumption of active ions such as Li during the charging and discharging process, and the molar content of Li is different when the battery cell 7 is discharged to different states. In the enumeration of the positive electrode active material in the embodiments of the present application, the molar content of Li is the initial state of the material, i.e., the state before feeding, and the positive electrode active material is applied to the battery system. After charging and discharging cycles, the molar content of Li can change.

[0116] In the enumeration of the positive electrode active material in the embodiments of the present application, the molar content of oxygen O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen O to change. In fact, the molar content of oxygen O will fluctuate.

[0117] In some embodiments, the positive electrode can use a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When the foamed metal is used as the positive electrode, the surface of the foamed metal can not be provided with a positive electrode active material layer, of course, a positive electrode active material layer can also be provided. As an example, the foamed metal can also be filled or / and deposited with a lithium source material, a potassium metal or a sodium metal, and the lithium source material is a lithium metal and / or a lithium-rich material.

[0118] In some embodiments, the positive electrode active material layer can also optionally include a positive electrode conductive agent. The embodiments of the present application do not have special limitations on the type of positive electrode conductive agent. As an example, the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the positive electrode conductive agent in the positive electrode active material layer is ≤5wt%.

[0119] In some embodiments, the positive electrode active material layer can also optionally include a positive electrode binder. The present embodiments do not have particular limitations on the type of positive electrode binder, and as an example, the positive electrode binder can include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic resin. In some embodiments, the mass percentage content of the positive electrode binder in the positive electrode active material layer is ≤ 5 wt%.

[0120] The positive electrode active material layer is typically formed by coating a positive electrode slurry on a positive electrode current collector, drying, and cold-pressing. The positive electrode slurry is typically formed by dispersing and uniformly stirring a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0121] In some embodiments, the battery cell is an ionic battery such as a lithium ion battery, and the negative electrode can be a negative electrode sheet, which can include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

[0122] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0123] As an example, the negative electrode current collector can adopt a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, or a carbon, nickel, or titanium, etc. can be used. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0124] As an example, the negative active material can employ a negative active material for a battery cell 7 known in the art. As an example, the negative active material can include one or more of: a carbon material (e.g., the carbon material includes one or more of artificial graphite, natural graphite, soft carbon, hard carbon), a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can include one or more of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can include one or more of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material layer for a battery can also be used. These negative active material layers can be used alone or in combination with two or more.

[0125] In some embodiments, the negative active material layer can also optionally include a negative conductive agent. The present embodiments do not have a particular limitation on the type of negative conductive agent, and as an example, the negative conductive agent can include one or more of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon fibers. In some embodiments, the mass percentage content of the negative conductive agent in the negative active material layer is ≤ 5 wt%.

[0126] In some embodiments, the negative active material layer can also optionally include a negative binder. The present embodiments do not have a particular limitation on the type of negative binder, and as an example, the negative binder can include one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage content of the negative binder in the negative active material layer is ≤ 5 wt%.

[0127] In some embodiments, the negative active material layer can also optionally include other auxiliary agents. As an example, the other auxiliary agents can include a thickening agent, such as carboxymethyl cellulose sodium (CMC-Na), a PTC thermistor material, etc. In some embodiments, the mass percentage content of the other auxiliary agents in the negative active material layer is ≤ 2 wt%.

[0128] In some embodiments, the battery cell 7 also includes an electrolyte. During charging and discharging of the battery cell, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet, and the electrolyte functions to conduct the active ions between the positive electrode sheet and the negative electrode sheet. The present embodiments do not have a particular limitation on the type of electrolyte, and the electrolyte can be selected as needed.

[0129] The electrolyte can include a solid-state electrolyte, for example, a solid-state electrolyte disposed in a form of a film layer between the positive electrode tab and the negative electrode tab. For example, the positive electrode tab, the solid-state electrolyte layer, and the negative electrode tab are stacked, and the solid-state electrolyte layer can be coated on a surface of the positive active material layer in the positive electrode tab or on a surface of the negative active material layer in the negative electrode tab.

[0130] In some embodiments, the solid-state electrolyte includes one or more of a sulfide solid-state electrolyte, an oxide solid-state electrolyte, a halide solid-state electrolyte, and a polymer solid-state electrolyte.

[0131] The sulfide solid-state electrolyte includes one or more of a sulfide crystalline solid-state electrolyte, a sulfide glass, and a glass-ceramic solid-state electrolyte.

[0132] In some embodiments, the sulfide solid-state electrolyte includes Li 10 GeP2S 12 , Li6PS5Cl, Li 10 Sn P2S 12 , Li2S-P2S5, Li2S-SiS2, and Li2S-B2S3.

[0133] The oxide solid-state electrolyte includes two categories of oxide crystalline and oxide glassy (amorphous) according to the classification of material structure, wherein the oxide crystalline electrolyte includes one or more of perovskite type, NASICON type, LISICON type, and garnet type, and the oxide glassy oxide electrolyte is, for example, a LiPON type electrolyte.

[0134] In some embodiments, the oxide solid-state electrolyte includes Li 3.3 La 0.56 TiO3, LiTi2(PO4)3, Li 14 Zn(GeO4)4, Li7La3Zr2O 12 , Li 1+x Al x Ti 2-x (PO4)3(0<x<2), Li 7-a La3Zr 2-a M a O 12 (M includes one or more of Ta and Nb; 0<a<2), Li b La 2 / 3-b TiO3(0<b<2), LiAlO2, Li2ZrO3, and Li4Ti5O 12 .

[0135] In some embodiments, the halide solid-state electrolyte comprises one or more of Li3YCl6, Li3ErCl6, Li3YBr6, Li3InBr6, Li3InCl6.

[0136] The polymer solid-state electrolyte SPE is mainly composed of a polymer matrix and an electrolyte salt. The electrolyte salt can comprise a lithium salt, which can comprise one or more of lithium hexafluorophosphate LiPF6, lithium perchlorate LiClO4, lithium hexafluoroarsenate LiAsF6, lithium tetrafluoroborate LiBF4. The electrolyte salt can comprise a sodium salt, which can comprise one or more of sodium hexafluorophosphate NaPF6, sodium perchlorate NaClO4, sodium hexafluoroarsenate NaAsF6, sodium tetrafluoroborate NaBF4.

[0137] In some embodiments, the SPE comprises one or more of a polyepoxy, a polyester, a polyalkoxy, a polyolefin, a polyacrylonitrile PAN, a single-ion polymer electrolyte. For example, the polyepoxy comprises one or more of polyethylene oxide PEO, polypropylene oxide PPO. The polyolefin comprises one or more of polyvinylidene fluoride PVDF, polyvinylidene chloride PVDC. The polyester comprises one or more of a polycarbonate, a polymethyl methacrylate PMMA. The polycarbonate comprises one or more of polypropylene carbonate, polytrimethylene carbonate.

[0138] Further, the polymer matrix can be inorganic particle hybridized, the inorganic particles comprising one or more of metal oxide nanoparticles such as MgO, Al2O3, SiO2, and zeolite, montmorillonite, etc. The addition of the inorganic particles can reduce the crystallinity, and the interaction between the polymer matrix, the lithium salt, and the inorganic particles can improve the conductivity and the ion transference number. The inorganic particles can also adsorb trace impurities such as moisture in the electrolyte and improve the mechanical properties.

[0139] In the embodiments of the present application, the polymer matrix and the electrolyte salt can be added to a solvent such as N,N-dimethylformamide, uniformly dispersed to obtain a slurry, and then inverted mold formed to obtain the polymer solid-state electrolyte.

[0140] In the embodiments of the present application, the electrode assembly 10 is in a wound structure or a stacked structure, and can be in a stacked structure.

[0141] When the electrode assembly 10 is in a wound structure, the positive electrode sheet is in a whole sheet structure, the negative electrode sheet is in a whole sheet structure, and the positive electrode sheet and the negative electrode sheet are wound in the same direction.

[0142] When the electrode assembly 10 is in a stacked structure, the positive electrode sheets are multiple, the negative electrode sheets are multiple, and the multiple positive electrode sheets and the multiple negative electrode sheets are stacked.

[0143] As shown in FIG. 5, in some embodiments, the electrode assembly 10 includes a plurality of electrode tabs and a solid-state electrolyte layer 50, the plurality of electrode tabs are stacked along the thickness direction X of the electrode assembly 10, and the solid-state electrolyte layer 50 is located between two adjacent electrode tabs, the electrode tab includes a current collector and an active material layer disposed on at least one side of the current collector, and at least one side of the electrode assembly along the thickness direction is the current collector.

[0144] At least one side of the electrode assembly 10 along the thickness direction X is the current collector, which can mean that one side of the electrode assembly 10 along the thickness direction X is the current collector, and the other side is the active material layer; or both sides of the electrode assembly 10 along the thickness direction X are the current collectors.

[0145] When at least one side of the electrode assembly 10 along the thickness direction X is the current collector, the electrode assembly 10 does not include an active material layer that cannot participate in charging and discharging outside the side, which can improve the occupied space of the active material layer that participates in charging and discharging, thereby improving the energy density of the battery cell;

[0146] When both sides of the electrode assembly 10 along the thickness direction X are the current collectors, both sides of the electrode assembly 10 do not include an active material layer that cannot participate in charging and discharging, i.e., an invalid active material layer, which can further improve the occupied space of the active material layer that participates in charging and discharging, thereby further improving the energy density of the battery cell.

[0147] In some embodiments, the plurality of electrode tabs includes a plurality of first tabs 30 and a plurality of second tabs 40, the first tab 30 includes a first current collector 31 and a first active material layer 32, and the first active material layer 32 is disposed on at least one side of the first current collector 31 along the thickness direction X of the electrode assembly 10; the second tab 40 includes a second current collector 41 and a second active material layer 42, and the second active material layer 42 is disposed on at least one side of the second current collector 41 along the thickness direction X, and the polarity of the first tab 30 and the second tab 40 is opposite, wherein the plurality of first tabs 30 and the plurality of second tabs 40 are stacked along the thickness direction X.

[0148] At least one side of the electrode assembly 10 along the thickness direction X is the current collector, which can be the first current collector 31 or the second current collector 41.

[0149] As shown in FIG. 5, for example, the electrode assembly 10 has the first tab 30 on both sides in the thickness direction X, specifically, the electrode assembly 10 has the first current collector 31 of the first tab 30 on both sides in the thickness direction X; in other words, the first tab 30 inside the electrode assembly 10 includes the first current collector 31 and the first active material layer 32 disposed on both sides of the first current collector 31, and the first tab 30 on both sides of the electrode assembly 10 includes the first current collector 31 and the first active material layer 32 disposed on one side of the first current collector 31. Of course, the first tab 30 inside the electrode assembly 10 can include the first current collector 31 and the first active material layer 32 disposed on one side of the first current collector 31.

[0150] FIG. 6 is a structural schematic diagram of an electrode assembly in a battery cell according to some embodiments of the present application.

[0151] As shown in FIG. 6, for example, the electrode assembly 10 has the second tab 40 on both sides in the thickness direction X, specifically, the electrode assembly 10 has the second current collector 41 of the second tab 40 on both sides in the thickness direction X; in other words, the second tab 40 inside the electrode assembly 10 includes the second current collector 41 and the second active material layer 42 disposed on both sides of the second current collector 41, and the second tab 40 on both sides of the electrode assembly 10 includes the second current collector 41 and the second active material layer 42 disposed on one side of the second current collector 41. Of course, the second tab 40 inside the electrode assembly 10 can include the second current collector 41 and the second active material layer 42 disposed on one side of the second current collector 41.

[0152] For another example, the electrode assembly 10 has the first tab 30 on one side in the thickness direction X and the second tab 40 on the other side, specifically, the electrode assembly 10 has the first current collector 31 of the first tab 30 on one side in the thickness direction X and the second current collector 41 of the second tab 40 on the other side; in other words, the first tab 30 inside the electrode assembly 10 includes the first current collector 31 and the first active material layer 32 disposed on both sides of the first current collector 31, and the second tab 40 inside the electrode assembly 10 includes the second current collector 41 and the second active material layer 42 disposed on both sides of the second current collector 41. Of course, the first tab 30 inside the electrode assembly 10 can include the first current collector 31 and the first active material layer 32 disposed on one side of the first current collector 31. The second tab 40 inside the electrode assembly 10 can include the second current collector 41 and the second active material layer 42 disposed on one side of the second current collector 41.

[0153] FIG. 7 is a structural schematic diagram of a first tab in a battery cell according to some embodiments of the present application.

[0154] As shown in FIG. 7, in some embodiments, the projection of the current collector along the thickness direction X has a rectangular profile; for example, the projection of the first current collector 31 along the thickness direction X has a rectangular profile; for another example, the projection of the second current collector 41 along the thickness direction X has a rectangular profile.

[0155] The edge or internal corner of the current collector is a right angle, i.e. 90°, so that the overall area of the current collector carrying the active material layer is increased, which is beneficial to improve the energy density of the battery cell.

[0156] In the embodiments of the present application, when the first electrode tab 30 is a positive electrode tab, the first current collector 31 is a positive current collector, and the first active material layer 32 is a positive active material layer; correspondingly, when the second electrode tab 40 is a negative electrode tab, the second current collector 41 is a negative current collector, and the second active material layer 42 is a negative active material layer.

[0157] In the embodiments of the present application, when the first electrode tab 30 is a positive electrode tab, the first current collector 31 is a positive current collector, and the first active material layer 32 is a positive active material layer; correspondingly, when the second electrode tab 40 is a negative electrode tab, the second current collector 41 is a negative current collector, and the second active material layer 42 is a negative active material layer.

[0158] The present application also provides a preparation method of an electrode assembly.

[0159] FIG. 8 is a flowchart of the preparation method of the electrode assembly provided by some embodiments of the present application.

[0160] As shown in FIG. 8, the preparation method comprises:

[0161] Step S110, providing a to-be-pressed electrode assembly, at least one side of the to-be-pressed electrode assembly along its own thickness direction is an outermost active material layer;

[0162] Step S120, sticking an adhesive layer on the outermost active material layer to form an intermediate assembly;

[0163] Step S130, pressing the intermediate assembly to obtain a pressed assembly, the density of the pressed assembly satisfies a first preset density;

[0164] Step S140, removing the adhesive layer and the outermost active material layer of the pressed assembly to form an electrode assembly.

[0165] The embodiments of the present application can improve the occupied space of the active material layer that can participate in charging and discharging by removing the invalid active material layer on the outermost side of the to-be-pressed electrode assembly, thereby improving the energy density of the battery cell.

[0166] Step S110, providing a to-be-pressed electrode assembly.

[0167] In some embodiments, step S110 can comprise:

[0168] The to-be-pressed electrode assembly is provided with the outermost active material layer on both sides along the thickness direction thereof.

[0169] In some embodiments, the step S110 can include:

[0170] The step S111 provides a plurality of first electrode tabs, each of which includes a first current collector and a first active material layer arranged on both sides of the first current collector along the thickness direction;

[0171] The step S112 provides a plurality of second electrode tabs, each of which includes a second current collector and a second active material layer arranged on both sides of the second current collector along the thickness direction, and the polarity of the second electrode tab is opposite to that of the first electrode tab.

[0172] The step S113 provides a plurality of solid-state electrolyte layers.

[0173] The step S114 alternately stacks the first electrode tab, the solid-state electrolyte layer, and the second electrode tab along the thickness direction to obtain the to-be-pressed electrode assembly.

[0174] FIG. 9 is a structural schematic diagram of a to-be-pressed electrode assembly according to some embodiments of the present application.

[0175] As shown in FIG. 9, when the first electrode tab 30 is located at the outermost side of the to-be-pressed electrode assembly 10 along the thickness direction X, the first active material layer 32 of the first electrode tab 30 is located at the outermost side of the to-be-pressed electrode assembly 10, i.e., the outermost active material layer is the first active material layer 32.

[0176] When the second electrode tab 40 is located at the outermost side of the to-be-pressed electrode assembly 10 along the thickness direction X, the second active material layer 42 of the second electrode tab 40 is located at the outermost side of the to-be-pressed electrode assembly 10, i.e., the outermost active material layer is the second active material layer 42.

[0177] It should be noted that in the embodiments of the present application, the steps S111, S112, and S113 have no sequence and can occur simultaneously or in steps.

[0178] In some embodiments, the projection of the first current collector along the thickness direction has a rectangular contour. The edges of the first current collector are right angles, so that the area of the first current collector carrying the active material layer as a whole is increased, which is conducive to improving the energy density of the battery cell.

[0179] In some embodiments, the projection of the second current collector along the thickness direction has a rectangular contour. The edges of the second current collector are right angles, so that the area of the second current collector carrying the active material layer as a whole is increased, which is conducive to improving the energy density of the battery cell.

[0180] In step S120, an adhesive layer is arranged on the electrode assembly to be pressed, the adhesive layer covers the outermost active material layer in the thickness direction, for example, the projection of the outermost active material layer in the thickness direction is located in the projection of the adhesive layer in the thickness direction, so as to facilitate the synchronous removal of the outermost active material layer when the adhesive layer is removed subsequently.

[0181] FIG. 10 is a schematic structural view of the electrode assembly to be pressed and the adhesive layer according to some embodiments of the present application. As shown in FIG. 10, the adhesive layer 60 is arranged on the first active material layer 32.

[0182] The adhesive layer is a film layer with a certain viscosity, so that the adhesive layer can be bonded with the outermost active material layer. For example, the peel strength of the adhesive layer is 1 N / m to 80 N / m, which can be selected as 60 N / m to 80 N / m, for example, 1 N / m, 5 N / m, 10 N / m, 15 N / m, 20 N / m, 25 N / m, 30 N / m, 35 N / m, 40 N / m, 45 N / m, 50 N / m, 55 N / m, 60 N / m, 65 N / m, 70 N / m, 75 N / m, 80 N / m or a range composed of any two of the above values. The adhesive layer can be arranged during the process of laminating the electrode assembly, or can be arranged after the process of laminating the electrode assembly.

[0183] In embodiments of the present application, the peel strength of the adhesive layer is the meaning known in the art, which can be tested by using the devices and methods known in the art, for example, according to GB / T 2792-2014 Test method for peel strength of adhesive tape.

[0184] In some embodiments, the shrinkage rate of the adhesive layer is 2.4% to 11.5%, for example, 2.4%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or a range composed of any two of the above values.

[0185] When the shrinkage rate of the adhesive layer is in the above range, the shrinkage ability is relatively strong, and the shrinkage amplitude is relatively large during the pressing process, which is more conducive to driving the outermost active material layer to peel off.

[0186] In embodiments of the present application, the shrinkage rate of the adhesive layer is the meaning known in the art, which can be tested by using the devices and methods known in the art, for example, according to GB / T 36363-2018 Test method for polyolefin separators for lithium ion batteries.

[0187] Optionally, the adhesive layer comprises one or more of polyolefin, polyimide, polyether, polylactic acid, polyacrylate, polyurethane, ethylene-vinyl acetate copolymer.

[0188] Exemplarily, the polyolefin material includes one or more of polyethylene, polypropylene, polytetrafluoroethylene, and polyvinyl chloride.

[0189] Exemplarily, the polyimide material includes one or more of polyimide, polyimide ether ketone, polyether imide, and polyimide ether sulfone.

[0190] Exemplarily, the polyether material includes one or more of polyvinyl ether and polyphenylene sulfide.

[0191] In step S130, the intermediate assembly is subjected to a pressing treatment, so that the internal density of the intermediate assembly is increased, the gap between the first electrode plate and the solid electrolyte layer is smaller, the first electrode plate and the solid electrolyte layer can be in surface-to-surface contact, and the gap between the second electrode plate and the solid electrolyte layer is also smaller, the second electrode plate and the solid electrolyte layer can be in surface-to-surface contact, which is beneficial to reducing the transmission resistance of active ions at the solid-solid interface. After the pressing treatment, the intermediate assembly can form an integrated structure.

[0192] FIG. 11 is a schematic view of a to-be-pressed electrode assembly in a pressing treatment according to some embodiments of the present application.

[0193] As shown in FIG. 11, the pressing treatment also makes the particles in the first active material layer more tightly packed, thereby increasing the compaction density of the first active material layer; and the particles in the second active material layer can also be more tightly packed, thereby increasing the compaction density of the second active material layer, thereby increasing the energy density of the battery cell. The arrows shown in FIG. 11 represent the direction of the force.

[0194] The pressing treatment can include one or more pressing processes. In the case of including multiple pressing processes, the pressing treatment can include a pre-pressing treatment and a re-pressing treatment. Through multiple pressing treatments, the density can be improved, and the energy density of the battery cell can be further improved.

[0195] Specifically, step S130 can include:

[0196] In step S131, the intermediate assembly is subjected to a pre-pressing treatment, so that the density of the intermediate assembly satisfies a second preset density.

[0197] In step S132, the intermediate assembly is subjected to a re-pressing treatment to obtain a pressed assembly, and the density of the pressed assembly satisfies a first preset density, which is greater than the second preset density.

[0198] In step S131, optionally, the second preset density can be 60% to 85%, for example, 60%, 65%, 70%, 75%, 80%, 85%, or a range composed of any two of the above values.

[0199] Pre-compression can be performed using either flat pressing or isostatic pressing, with flat pressing being the preferred option. Flat pressing applies force along the thickness direction to the intermediate component, making its interior more compact and allowing it to form a monolithic structure. This reduces misalignment between electrodes during subsequent processes. After pre-compression, the bonding force between the adhesive layer and the outermost active material layer is stronger, making it easier to remove the outermost active material layer when removing the adhesive layer.

[0200] For example, the flat pressing temperature is from 25°C to 200°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any range of two of the above values.

[0201] For example, the pressure for the flattening process is from 3 MPa to 20 MPa, such as 3 MPa, 5 MPa, 8 MPa, 10 MPa, 12 MPa, 15 MPa, 18 MPa, 20 MPa, or any range of two of the above values.

[0202] For example, the flattening process time is from 10s to 180s, such as 10s, 20s, 50s, 80s, 100s, 120s, 150s, 180s or any range of two of the above values.

[0203] For example, the flat pressing process uses a flat pressing plate, and the parallelism of the flat pressing plate is controlled to be 0.05mm to 0.50mm, such as 0.05mm, 0.10mm, 0.20mm, 0.30mm, 0.40mm, 0.50mm or any two of the above values.

[0204] In step S132, optionally, the first preset density can be greater than or equal to 94.0% and less than 100%, and can be selected as 94.0% to 97.5%, such as 94.0%, 94.5%, 95.0%, 95.5%, 96.0%, 96.5%, 97.0%, 97.5%, 98.0%, 98.5%, 99.0%, 99.5%, or a range of any two of the above values.

[0205] The re-lamination process can be performed using either flat pressing or isostatic pressing, with isostatic pressing being the preferred option. Isostatic pressing applies force to the intermediate component in all directions, making the interior of the intermediate component more compact. After isostatic pressing, the adhesion between the adhesive layer and the outermost active material layer is stronger, making it easier to remove the outermost active material layer when peeling off the adhesive layer.

[0206] The degree of densification of the electrode assembly can be characterized by density, for example, the calculation method is as follows:

[0207] In the formula, τ is the density; m is the mass; V is the volume; and p is the theoretical true density.

[0208] Optionally, the step S132 can include:

[0209] In step S1321, a packaging film is provided to the intermediate assembly to wrap the intermediate assembly, forming a to-be-static-pressed assembly.

[0210] In step S1322, the gas in the to-be-static-pressed assembly is extracted until the vacuum degree in the to-be-static-pressed assembly meets a preset vacuum degree.

[0211] In step S1323, after the to-be-static-pressed assembly is sealed, the to-be-static-pressed assembly is subjected to isostatic pressing to obtain a pressed assembly, and the density of the pressed assembly meets a first preset density.

[0212] In step S1324, the packaging film of the pressed assembly is removed.

[0213] The adhesive layer is adhered to the outside of the to-be-pressed electrode assembly, which can effectively reduce the risk of the electrode edge piercing the packaging film, and can reduce the risk of foreign matter contaminating the electrode assembly during the process. It can also buffer the force of the external member impacting the electrode assembly during the process.

[0214] The packaging film can effectively isolate the intermediate assembly from the isostatic pressing medium, reducing the risk of contamination of the active substance in the intermediate assembly. Optionally, the isostatic pressing medium can include one or more of gaseous medium, liquid medium. For example, the gaseous medium includes one or more of inert gases such as helium, neon or argon. For another example, the liquid medium includes one or more of water, silicone oil or dioctyl sebacate.

[0215] Optionally, the packaging film can adopt the outer shape structure of the intermediate assembly, for example, the intermediate assembly is a cuboid, and the packaging film adopts a similar cuboid structure. For another example, the intermediate assembly is a cylinder, and the packaging film adopts a similar cylindrical structure.

[0216] FIG. 12 is a structural schematic diagram of the packaging film provided by some embodiments of the present application;

[0217] As shown in FIG. 12, the encapsulation film 70 can include an encapsulation cavity 71 in which the intermediate assembly is arranged and an encapsulation cover 72 covering the encapsulation cavity 71, and the encapsulation cover 72 can extend beyond the encapsulation cavity 71, which is conducive to sealing the encapsulation film 70. Optionally, the tensile strength of the encapsulation film is 20 N to 85 N, for example, 20 N, 25 N, 30 N, 35 N, 40 N, 45 N, 50 N, 55 N, 60 N, 65 N, 70 N, 75 N, 80 N, 85 N, or a range formed by any two of the above values. When the tensile strength of the encapsulation film is in the above range, after the sealing process, there can still be some space in the isostatic pressure assembly, which can provide a gas storage space for the gas squeezed out during the isostatic pressure process, which is conducive to further improving the density.

[0218] In the embodiments of the present application, the tensile strength of the encapsulation film is the meaning known in the art, which can be measured by using the equipment and method known in the art, and can be tested according to GB / T 36363-2018 Polyolefin Separator for Lithium Ion Battery.

[0219] Optionally, the material of the encapsulation film includes one or more of polyolefin material, polyimide material, polyphenylene sulfide, and metal material.

[0220] For example, the polyolefin material includes one or more of polyethylene, polypropylene, and polytetrafluoroethylene.

[0221] For example, the polyimide material includes one or more of polyimide, polyimide ether ketone, polyether imide, and polyimide ether sulfone.

[0222] For example, the metal material includes one or more of aluminum, copper, and steel.

[0223] In step S1322, the preset vacuum degree can be -100 KPa to -50 KPa, for example, -100 KPa, -90 KPa, -80 KPa, -70 KPa, -60 KPa, -50 KPa, or a range formed by any two of the above values.

[0224] In step S1323,

[0225] For example, the temperature of the isostatic pressure process is 0℃ to 250℃, for example, 0℃, 10℃, 20℃, 30℃, 50℃, 80℃, 100℃, 120℃, 150℃, 180℃, 200℃, 220℃, 250℃, or a range formed by any two of the above values.

[0226] Exemplarily, the pressure of the isostatic pressing treatment is 100 MPa to 2000 MPa, for example, 100 MPa, 200 MPa, 300 MPa, 400 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa, 900 MPa, 1000 MPa, 1100 MPa, 1200 MPa, 1300 MPa, 1400 MPa, 1500 MPa, 1600 MPa, 1700 MPa, 1800 MPa, 1900 MPa, 2000 MPa, or a range between any two of the above values.

[0227] Exemplarily, the time of the isostatic pressing treatment is 1 min to 90 min, for example, 1 min, 5 min, 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, or a range between any two of the above values.

[0228] The application further provides a preparation method of a battery cell.

[0229] FIG. 13 is a flowchart of a preparation method of a battery cell according to some embodiments of the application. As shown in FIG. 13, the preparation method comprises:

[0230] S100, providing an electrode assembly;

[0231] S200, assembling the electrode assembly into a shell to obtain a battery cell.

[0232] The step of providing the electrode assembly can adopt the preparation steps of the electrode assembly described above. Specifically, the preparation method of the battery cell can comprise:

[0233] S110, providing a to-be-pressed electrode assembly, the to-be-pressed electrode assembly having an outermost active material layer on at least one side along the thickness direction thereof;

[0234] S120, adhering an adhesive layer on the outermost active material layer to obtain an intermediate assembly;

[0235] S130, pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density;

[0236] S140, removing the adhesive layer and the outermost active material layer of the pressed assembly to obtain the electrode assembly;

[0237] S200, assembling the electrode assembly into a shell to obtain a battery cell.

[0238] The embodiments of the present application can improve the space occupied by the active material layers that can participate in charging and discharging by removing the outermost active material layers of the electrode assembly to be pressed, thereby improving the energy density of the battery cell.

[0239] The embodiments of the method for preparing the electrode assembly of the present application can include:

[0240] The edges of the first and second electrode sheets are cut into right angles;

[0241] The first electrode sheet, the solid-state electrolyte layer and the second electrode sheet are stacked to form an electrode assembly to be pressed, and the two sides of the electrode assembly to be pressed along the thickness direction are the outermost active material layers;

[0242] An adhesive layer is arranged on the two sides of the electrode assembly to be pressed to form an intermediate assembly;

[0243] The intermediate assembly is subjected to a flat pressing process to form an integrated structure;

[0244] The intermediate assembly is subjected to an isostatic pressing process to form a pressed assembly, so that the density of the pressed assembly meets the first preset density;

[0245] The adhesive layer and the outermost active material layers are removed to form an electrode assembly.

[0246] Embodiments

[0247] The following embodiments more specifically describe the content disclosed by the embodiments of the present application, and these embodiments are only used for illustrative description, because various modifications and changes within the scope of the content disclosed by the embodiments of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods, and can be directly used without further treatment, and the instruments used in the embodiments are commercially available.

[0248] Embodiments

[0249] 1. Preparation of a laminated electrode assembly

[0250] The negative electrode sheet, the solid-state electrolyte layer and the positive electrode sheet are stacked, the negative electrode sheet is located at the outermost side, the negative electrode sheet includes a negative electrode current collector and negative electrode active material layers arranged on both sides of the negative electrode current collector, and the positive electrode sheet includes a positive electrode current collector and positive electrode active material layers arranged on both sides of the positive electrode current collector; the inner angles of the positive electrode sheet and the negative electrode sheet are right angles;

[0251] The adhesive layer is located on the surface of the negative active material layer of the outermost negative electrode sheet, forming an intermediate assembly; before stacking, an adhesive layer is placed in advance, and then the negative electrode sheet, the solid-state electrolyte layer, the positive electrode sheet and the negative electrode sheet are placed in sequence on the adhesive layer; after the stacking is completed, an adhesive layer is arranged on the surface of the negative active material layer of the outermost negative electrode sheet.

[0252] The intermediate assembly is integrally subjected to flat pressing and pre-pressing treatment, the flat pressing and pre-pressing temperature is 85℃, the pressure is 10MPa, the time is 60s, and the parallelism of the pressing plate is 0.1mm.

[0253] The intermediate assembly is packaged with a packaging film to form a to-be-static-pressing assembly.

[0254] The gas in the to-be-static-pressing assembly is extracted until the vacuum degree in the to-be-static-pressing assembly is -95KPa.

[0255] The to-be-static-pressing assembly is sealed.

[0256] The to-be-static-pressing assembly is subjected to isostatic pressing treatment, the isostatic pressing medium is silicone oil, the temperature is 150℃, the pressure is 800MPa, and the time is 5min.

[0257] The packaging film is removed, the adhesive layer is torn off, and the outermost active material layer is peeled off.

[0258] 2. Preparation of a laminated battery monomer

[0259] The laminated electrode assembly is placed in a shell, and subjected to vacuum packaging, standing, formation, shaping and other processes to obtain a laminated battery monomer.

[0260] Comparative example

[0261] 1. Preparation of a laminated electrode assembly

[0262] The negative electrode sheet, the solid-state electrolyte layer and the positive electrode sheet are stacked and arranged, the negative electrode sheet is located at the outermost side, the negative electrode sheet comprises a negative current collector and negative active material layers arranged on both sides of the negative current collector, and the positive electrode sheet comprises a positive current collector and positive active material layers arranged on both sides of the positive current collector; the edge of the negative electrode sheet is a cut-off chamfer, and the edge of the positive electrode sheet is a cut-off chamfer, i.e., the edge is a round corner.

[0263] The intermediate assembly is integrally subjected to flat pressing and pre-pressing treatment, the flat pressing and pre-pressing temperature is 85℃, the pressure is 10MPa, the time is 60s, and the parallelism of the pressing plate is 0.1mm.

[0264] The intermediate assembly is packaged by a packaging film to form a to-be-static-pressure assembly; gas in the to-be-static-pressure assembly is extracted until the vacuum degree in the to-be-static-pressure assembly is -95 KPa; the to-be-static-pressure assembly is sealed; the to-be-static-pressure assembly is isostatic pressure treated, the isostatic pressure medium is silicon oil, the temperature is 150 DEG C, the pressure is 800 MPa, and the time is 5 min; and the packaging film is removed.

[0265] The adhesive is arranged on the surface of the electrode assembly, and the surface of the electrode assembly includes a main surface and a side surface, the area of the main surface is larger than that of the side surface, the main surface is connected with the side surface, and the adhesive is arranged on the main surface of the electrode assembly.

[0266] 2. Preparation of the laminated battery monomer

[0267] The laminated electrode assembly is placed in the shell, and the laminated battery monomer is obtained through the processes of vacuum packaging, standing, formation, shaping and the like.

[0268] Performance test:

[0269] 1. Flatness test of the laminated electrode assembly

[0270] (1) The battery monomer to be tested is placed on a marble platform, and the battery monomer is fixed by using a 2kg·f pressure;

[0271] (2) The flatness value of the output battery monomer is obtained by using laser surface scanning,

[0272] The flatness can represent the deviation of the macroscopic concave-convex height of the surface of the battery monomer from the ideal plane, and the smaller the flatness is, the more flat the surface is.

[0273] 2. Density test of the laminated electrode assembly

[0274] (1) The sample is weighed by using an analytical balance, and the mass of the electrode assembly is m;

[0275] (2) The geometric volume of the sample is tested by using Three Dimensions (3D) scanning, and the volume of the electrode assembly is V, and the ratio of the mass m of the electrode assembly to the volume V is the apparent density m / V;

[0276] (3) The theoretical true density of the sample is measured by using the helium replacement method, and the ratio of the apparent density m / V to the theoretical true density p is the density.

[0277] 3. Energy density of the battery monomer

[0278] As used herein, the term "energy density" refers to the volume (typically expressed in Wh / L) or weight (typically expressed in Wh / kg) of energy (Wh or mWh) delivered during each cycle of charge / discharge can be tested from the battery device tester.

[0279] Take the weight energy density as an example. At a constant voltage (the positive active material of the examples and the comparative examples is selected to be a layered transition metal oxide NCM811, and the constant voltage is 4.25 V), the first cycle discharge capacity (Ah) is multiplied by the ratio of the discharge voltage to the mass of the battery monomer.

[0280] First cycle discharge capacity: charged at a constant current of 1C to 4.25 V, then charged at 4.25 V constant voltage until the current drops to 0.05C, and then discharged at a constant current of 1C to 2.8 V. The capacity released in this process is the first cycle discharge capacity (Ah).

[0281] Weight energy density = first cycle discharge capacity (Ah) x discharge voltage (4.25 V) / mass of battery monomer (kg).

[0282] In the manner of Example 1, a plurality of stacked electrode assemblies S1 to S5 were prepared, which were respectively prepared as battery monomers, and statistical analysis was performed, as shown in Table 1:

[0283] Table 1

[0284] In Table 1, Comparative Example 1 uses a similar pressing process as Example 1, and the density of the electrode assembly is basically the same.

[0285] The improvement of the energy density of the battery monomer in the examples is based on the calculation of the energy density of the battery monomer in the comparative examples.

[0286] As can be seen from Table 1, the energy density of the battery monomer can be improved by bonding the outermost active material layer through the bonding layer according to the embodiments of the application.

[0287] Moreover, the bonding layer can basically remove all the outermost active material layer, and the flatness of the surface after removal is small, for example, less than or equal to 0.0240 mm, which can be selected to be 0.01 mm to 0.025 mm, and can be selected to be 0.01 mm to 0.015 mm, and the surface is relatively smooth.

[0288] Although the application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the application, and equivalent components can be substituted therefor. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A method for preparing a battery cell, comprising: providing a to-be-pressed electrode assembly, the to-be-pressed electrode assembly having an outermost active material layer on at least one side along a thickness direction thereof; adhering an adhesive layer to the outermost active material layer to form an intermediate assembly; pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density; removing the adhesive layer and the outermost active material layer of the pressed assembly to form an electrode assembly; assembling the electrode assembly into a shell to obtain the battery cell. The production method according to claim 1, wherein, The step of pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density, comprises: pre-pressing the intermediate assembly to a density satisfying a second preset density; re-pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density, the first preset density being greater than the second preset density. The production method according to claim 2, wherein, The second preset density is 60% to 85%. The production method according to claim 2 or 3, wherein The step of pre-pressing the intermediate assembly to a density satisfying a second preset density, comprises: flat pressing the intermediate assembly to a density satisfying a second preset density. The production method according to claim 4, wherein The flat pressing has a temperature of 25°C to 200°C; and / or The flat pressing has a pressure of 3MPa to 20MPa; and / or The flat pressing has a time of 10s to 180s. The production method according to any one of claims 1 to 5, wherein The first preset density is greater than or equal to 94.0% and less than 100%. The production method according to claim 6, wherein The first preset density is 94.0% to 97.5%. The production method according to any one of claims 2 to 7, wherein The step of re-pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density, comprises: isostatic pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density. The production method according to claim 8, wherein The step of isostatic pressing the intermediate assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density, comprises: providing an encapsulation film to the intermediate assembly to wrap the intermediate assembly to form a to-be-isostatic-pressed assembly; extracting gas in the to-be-isostatic-pressed assembly until a vacuum degree in the to-be-isostatic-pressed assembly satisfies a preset vacuum degree; after sealing the to-be-isostatic-pressed assembly, isostatic pressing the to-be-isostatic-pressed assembly to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density; removing the encapsulation film of the pressed assembly. The production method according to claim 9, wherein The encapsulation film has a tensile strength of 20N to 85N. The method of preparation according to claim 10, wherein, The material of the encapsulation film comprises one or more of polyolefin, polyimide, metal, and polyphenylene sulfide. The method of preparation according to claim 11, wherein, The polyolefin comprises one or more of polyethylene, polypropylene, and polytetrafluoroethylene; and / or The polyimide comprises one or more of polyimide, polyimide ether ketone, polyether imide, and polyimide ether sulfone; and / or The metal comprises one or more of aluminum, copper, and steel. The production method according to any one of claims 9 to 12, wherein The preset vacuum degree is -100KPa to -50KPa. The production method according to any one of claims 8 to 13, wherein The isostatic pressing has a temperature of 0°C to 250°C; and / or The pressure of the isostatic pressing treatment is 100 MPa to 2000 MPa; and / or The time of the isostatic pressing treatment is 1 min to 90 min. The production method according to any one of claims 1 to 14, wherein The peeling strength of the adhesive layer is 1 N / m to 80 N / m; and / or the shrinkage of the adhesive layer is 2.4% to 11.5%. The method of manufacturing according to claim 15, wherein, The adhesive layer comprises one or more of polyolefin material, polyimide material, polyether material, polylactic acid, polyacrylate, polyurethane, and ethylene-vinyl acetate copolymer. The method of manufacturing according to claim 16, wherein, The polyolefin material comprises one or more of polyethylene, polypropylene, and polytetrafluoroethylene; and / or The polyimide material comprises one or more of polyimide, polyimide ether ketone, polyether imide, and polyimide ether sulfone; and / or The polyether material comprises one or more of polyvinyl ether and polyphenylene sulfide. The production method according to any one of claims 1 to 17, wherein The step of providing the electrode assembly to be pressed, at least one side of the electrode assembly along its own thickness direction being the outermost active material layer, comprises: providing a plurality of first electrode sheets, each of the first electrode sheets comprising a first current collector and a first active material layer, the first active material layer being disposed on both sides of the first current collector along the thickness direction; providing a plurality of second electrode sheets, each of the second electrode sheets comprising a second current collector and a second active material layer, the second active material layer being disposed on both sides of the second current collector along the thickness direction, the polarity of the second electrode sheets being opposite to that of the first electrode sheets; providing a plurality of solid electrolyte layers; alternately stacking the first electrode sheets, the solid electrolyte layers, and the second electrode sheets along the thickness direction to obtain the electrode assembly to be pressed, wherein the first electrode sheets are located at the outermost side of the electrode assembly to be pressed along the thickness direction, and the outermost active material layer is the first active material layer; or the second electrode sheets are located at the outermost side of the electrode assembly to be pressed along the thickness direction, and the outermost active material layer is the second active material layer. The method of manufacturing according to claim 18, wherein, The projection of the first current collector along the thickness direction has a rectangular contour; and / or The projection of the second current collector along the thickness direction has a rectangular contour. The production method according to any one of claims 1 to 19, wherein The outermost active material layer comprises a positive electrode active material; or the outermost active material layer comprises a negative electrode active material. The production method according to any one of claims 1 to 20, wherein Both sides of the electrode assembly to be pressed along the thickness direction are the outermost active material layers. A battery cell includes an electrode assembly including a solid-state electrolyte layer and a plurality of electrode tabs stacked in a thickness direction of the electrode assembly, the solid-state electrolyte layer being positioned between adjacent two of the electrode tabs, the electrode tab including a current collector and an active material layer provided on at least one side of the current collector, wherein, At least one side of the electrode assembly along the thickness direction is a current collector. A method for preparing an electrode assembly, comprising: providing an electrode assembly to be pressed, at least one side of the electrode assembly along its own thickness direction being an outermost active material layer; adhesively disposing an adhesive layer on the outermost active material layer to form an intermediate assembly; subjecting the intermediate assembly to a pressing treatment to obtain a pressed assembly, the pressed assembly having a density satisfying a first preset density; removing the adhesive layer and the outermost active material layer of the pressed assembly to form the electrode assembly. An electrode assembly includes a plurality of electrode tabs and a solid-state electrolyte layer, the plurality of electrode tabs are stacked along a thickness direction of the electrode assembly, the solid-state electrolyte layer is located between two adjacent electrode tabs, the electrode tab includes a current collector and an active material layer disposed on at least one side of the current collector, wherein, At least one side of the electrode assembly along the thickness direction is a current collector. A battery device comprising a battery cell obtained by the method according to any one of claims 1 to 21, or the battery cell according to claim 22. A power utilization device comprising the battery device according to claim 25.

Images