Solid-state battery, method of manufacturing the same, and electric device

Abstract

The application relates to a solid-state battery, a preparation method thereof and an electric device, and belongs to the technical field of solid-state batteries. The solid-state battery provided by the application comprises a battery core and a coating layer wrapped on the surface of the battery core; the battery core comprises a positive electrode sheet, a negative electrode sheet and a solid-state electrolyte layer, and the solid-state electrolyte layer is located between the positive electrode sheet and the negative electrode sheet; the coating layer is formed by solidifying a plurality of polymer films which are attached to and wound on the surface of the battery core after being fused into one body through heating treatment, so as to provide a constraint force in the thickness direction of the positive electrode sheet and the negative electrode sheet. The coating layer can improve the cycle life, energy density and production efficiency of the solid-state battery, and is suitable for large-scale production.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and in particular to a solid-state battery, its preparation method and power application device. Background Technology

[0002] In recent years, batteries have gradually become an energy storage medium for emerging energy sources, and they also play an increasingly important role in industry as power sources for portable electronic devices. Lithium-ion batteries, characterized by high energy density and high power density, are widely considered the most ideal portable power source. Traditional liquid lithium-ion batteries contain a large amount of flammable electrolyte, posing safety hazards. Since solid-state batteries do not contain electrolyte, they can effectively solve the battery safety problem. Therefore, solid-state lithium batteries have become a current research hotspot in the industry.

[0003] However, during cycling, solid-state batteries experience repeated electrode expansion, leading to delamination between the electrode and the current collector, internal electrode structural expansion and deformation, electrode pulverization, and increased resistance. This significantly impacts the cycle performance of solid-state batteries. Therefore, applying pressure to solid-state batteries is necessary to alleviate the electrode expansion problem. Traditional solid-state battery pressurization methods mainly fall into three categories:

[0004] The first method involves placing the positive electrode material, negative electrode material, and electrolyte material of a solid-state battery into a pressurized component mold and testing the performance of the solid-state battery through the mold. The size and capacity of the solid-state battery produced by this method are limited by the size of the mold, making it impossible to achieve large-scale production of solid-state batteries.

[0005] The second method involves applying pressure to the top and bottom sides of the solid-state battery after it has been manufactured. However, this method cannot apply pressure to the sides of the solid-state battery, and the device is too large and can easily cause the solid-state battery packaging to break, making it unsuitable for mass production of solid-state batteries.

[0006] The third method is to form a pressurized layer by casting polymer through a mold. However, this method has strict requirements for the casting mold and positioning equipment. Mechanical and human errors can cause the battery cell to shift inside the pressurized layer, resulting in uneven pressure intensity inside the pressurized layer. Furthermore, due to precision limitations, it is impossible to produce a pressurized layer within 1mm, which greatly reduces the energy density of the solid-state battery. At the same time, the production efficiency is low because the battery cell manufacturing process requires casting and cooling processes. Summary of the Invention

[0007] Therefore, it is necessary to provide a solid-state battery, its preparation method, and an electrical device to improve the cycle life, energy density, and production efficiency of solid-state batteries, and to make them suitable for large-scale production.

[0008] One aspect of this application provides a solid-state battery, the solid-state battery including a cell and a coating layer covering the surface of the cell;

[0009] The battery cell includes a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode;

[0010] The coating layer is formed by heating and fusing multiple polymer films bonded and wound on the surface of the battery cell into a single unit, and then curing it to provide a thickness-direction constraint on the positive electrode and the negative electrode.

[0011] In some embodiments, the raw materials for the polymer film include one or more of propylene copolymer, SBS thermoplastic rubber, SEBS thermoplastic rubber, polyoxymethylene, polycarbonate, silicone, thermoplastic polyurethane, isobutylene rubber, and chloroprene rubber.

[0012] In some embodiments, the thickness of the polymer film is 20 μm to 100 μm.

[0013] In some more specific embodiments, the thickness of the polymer film is 50 μm to 100 μm.

[0014] In some embodiments, the winding tension is 20N to 100N.

[0015] In some embodiments, the width of the polymer film is greater than or equal to the size of the cell in the direction perpendicular to the winding direction, so that the polymer film completely covers the surface of the cell to which it is attached.

[0016] In some embodiments, the polymer film has 10 to 100 winding layers.

[0017] In some embodiments, the thickness of the coating layer is 1 mm to 5 mm.

[0018] In some embodiments, the process conditions for the heat treatment include a heating temperature of 80°C to 190°C, a heating time of 2 min to 5 min, and a vacuum degree of -0.05 MPa to -0.1 MPa.

[0019] In some embodiments, the solid-state battery further includes a housing, with the battery cell and the covering layer located inside the housing.

[0020] Another aspect of this application provides a method for preparing the above-mentioned solid-state battery, comprising the following steps:

[0021] Provide the battery cell;

[0022] The polymer film is bonded to the surface of the battery cell and wound multiple times.

[0023] The battery cell, which is wound around the polymer film, is subjected to the heat treatment to fuse the polymer film into a whole, and then cooled and solidified to form the coating layer.

[0024] In some embodiments, the method for preparing the solid-state battery further includes the following steps: placing the cell with the coating layer into a casing and encapsulating it under a vacuum of -0.05MPa to -0.1MPa, and then subjecting it to isostatic pressure treatment of 10MPa to 500MPa.

[0025] In another aspect of this application, an electrical device is provided, comprising the solid-state battery described above or the solid-state battery prepared by the above method.

[0026] Compared with traditional technologies, the above-mentioned solid-state batteries, their preparation methods, and electrical devices have at least the following advantages:

[0027] (1) The coating layer in the solid-state battery is formed by heating and fusing multiple polymer films bonded and wound on the surface of the cell into one and then curing. The thickness of the coating layer can be controlled by the number of layers of the polymer film and the thickness of the polymer film. During the charging and discharging process of the solid-state battery, the coating layer provides a certain elastic pressure to the cell. The pressure effect can be achieved without the use of an external pressurizing device. This not only enhances the internal pressure of the solid-state battery and promotes material contact, but also effectively alleviates the problem of electrode sheet expansion and improves the cycle life of the solid-state battery. At the same time, the thickness of the coating layer can be precisely controlled without molds. This solves the problem of low production speed caused by the fixed number, precision and size of injection molds in the production process, provides a solution for increasing the output of solid-state lithium batteries, and improves the energy density of solid-state batteries.

[0028] (2) By heating the polymer film to fuse and shrink it into a whole, and then curing it to form a coating layer, the cell can be fully wrapped, which can achieve the effect of pressurizing the cell. Fusing and shrinking the polymer film into a whole is beneficial to make the cell subjected to uniform force, thereby improving the cycle life of solid-state batteries. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the cross-section of a traditional solid-state battery cell.

[0030] Figure 2 This is a schematic cross-sectional view of a solid-state battery cell according to one embodiment of this application.

[0031] Figure 3 This is a cross-sectional view of the solid-state battery in Embodiment 1 of this application after 100 cycles.

[0032] Figure 4 This is a cross-sectional view of the solid-state battery in Comparative Example 1 of this application after 100 cycles.

[0033] Figure 5 This is a comparison chart of the 100-cycle discharge capacity of solid-state batteries in Example 1 and Comparative Example 1 of this application.

[0034] Figure 6 This is a comparison chart of the solid-state battery's 100-cycle discharge capacity in Example 2 and Comparative Example 2 of this application.

[0035] Figure 7 This is a comparison chart of the 100-cycle discharge capacity of the solid-state batteries in Example 3 and Comparative Example 3 of this application.

[0036] Figure 8 This is a comparison chart of the solid-state battery's 100-cycle discharge capacity in Example 4 and Comparative Example 4 of this application.

[0037] Figure 9 This is a comparison chart of the solid-state battery capacity after 100 cycles of discharge between Example 5 and Comparative Example 5 of this application.

[0038] Figure 10 This is a comparison chart of the 100-cycle discharge capacity of the solid-state batteries in Example 6 and Comparative Example 6 of this application.

[0039] Figure 11 This is a diagram showing the 100-cycle discharge capacity of the solid-state battery in Embodiment 7 of this application.

[0040] Figure 1 and Figure 2 In the middle: 1-positive electrode; 2-solid electrolyte layer; 3-negative electrode; 4-coating layer. Detailed Implementation

[0041] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0042] In this application, unless otherwise defined, all technical terms and jargon not explicitly stated have the same meaning as commonly understood by those skilled in the art and are common knowledge to those skilled in the art. Methods not explicitly stated are all conventional methods known to those skilled in the art. The term "multiple" in this application means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0044] Combination Figure 1 In the traditional solid-state battery pressurized coating process, a positive electrode 1, a solid electrolyte layer 2, and a negative electrode 3 are stacked to form a battery cell. The cell is then placed in a fixed mold for positioning, injection molding, pressurization, and curing to obtain the pressurized coating layer 4. However, this method is difficult to implement in actual production. First, large positioning errors in the battery cell can lead to deviations in the thickness of the coating layer 4 and uneven stress within the cell, causing deformation. Second, the production output of the battery cell coating layer 4 is limited by the number of custom-made fixed molds, and the customization cycle and cost of a set of fixed molds are high. Third, because the dimensions of the fixed molds cannot be adjusted at any time, changes to the coating layer 4 thickness require readjustment of the mold dimensions or even a complete re-customization of the mold, resulting in low production efficiency.

[0045] Combination Figure 2 One embodiment of this application provides a solid-state battery, which includes a cell and a coating layer 4 covering the surface of the cell;

[0046] The battery cell includes a positive electrode 1, a negative electrode 3, and a solid electrolyte layer 2, with the solid electrolyte layer 2 located between the positive electrode 1 and the negative electrode 3;

[0047] The coating layer 4 is formed by heating and fusing multiple polymer films bonded and wound on the surface of the cell into one piece, and then curing it to provide a constraint force in the thickness direction to the positive electrode 1 and the negative electrode 3.

[0048] When the coating layer 4 formed by conventional casting or injection molding is thin, the battery cell is prone to misalignment, causing deviations in the thickness of the coating layer 4, resulting in uneven stress within the battery cell and deformation. The thickness of the coating layer 4 can be controlled by the number of winding layers of the polymer film and the thickness of the polymer film. Compared to the coating layer 4 formed by conventional casting or injection molding, the coating layer 4 provided in this embodiment is thinner while maintaining the cycle performance of the solid-state battery. Furthermore, the coating layer 4 is lighter than the coating layer 4 formed by conventional casting or injection molding at the same thickness, thereby effectively improving the energy density of the solid-state battery. The coating layer 4 of this embodiment has a certain degree of elasticity, making it an elastic coating layer that can completely cover the battery cell. During the charging and discharging process of solid-state batteries, the coating layer 4 provides a certain elastic pressure to the cell, achieving a pressurizing effect without the need for an external pressurizing device. This not only enhances the internal pressure of the solid-state battery, promotes material contact, effectively alleviates electrode sheet expansion problems, and improves the cycle life of the solid-state battery, but also allows for precise control of the coating layer 4 thickness without the need for molds. This solves the problem of low production speed caused by the limitations of the number, precision, and size of injection molds during the production process, providing a solution for increasing the production volume of solid-state lithium batteries. The aforementioned solid-state batteries include, but are not limited to, prismatic and cylindrical batteries. The assembly method of the positive and negative electrodes can be, for example, stacked or wound. This application does not impose any particular restrictions on the shape of the solid-state battery or the assembly method of the positive and negative electrodes.

[0049] Optionally, the above-mentioned positive electrode sheet 1 is prepared by the following method: 55wt% to 90wt% of positive electrode material, 5wt% to 40wt% of solid electrolyte, 0.5wt% to 10wt% of conductive agent and 0.5wt% to 5wt% of binder are mixed evenly, a solvent is added to make a positive electrode slurry, which is then coated on aluminum foil and dried. The mass percentage of the aforementioned positive electrode material can be, for example, 55 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt%; the mass percentage of the aforementioned solid electrolyte can be, for example, 5 wt%, 10 wt%, 20 wt%, 30 wt%, or 40 wt%; the mass percentage of the aforementioned conductive agent can be, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%; and the mass percentage of the aforementioned binder can be, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0050] Optionally, the above-mentioned negative electrode sheet 3 is prepared by the following method: 40wt% to 83wt% of negative electrode material, 8wt% to 45wt% of solid electrolyte, 0.5wt% to 10wt% of conductive agent and 0.5wt% to 5wt% of binder are mixed evenly, a solvent is added to make a negative electrode slurry, which is coated on copper foil and dried; or lithium metal is directly rolled onto copper foil as negative electrode sheet 3. The mass percentage of the aforementioned negative electrode material can be, for example, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 83 wt%; the mass percentage of the aforementioned solid electrolyte can be, for example, 8 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, or 45 wt%; the mass percentage of the aforementioned conductive agent can be, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%; and the mass percentage of the aforementioned binder can be, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0051] Optionally, the solid electrolyte layer 2 is prepared by the following method: 95wt% to 99.5wt% of solid electrolyte and 0.5wt% to 5wt% of binder are mixed evenly, a solvent is added to form a solid electrolyte slurry, which is then coated onto the surface of the positive electrode 1 and dried. The mass percentage of the solid electrolyte can be, for example, 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, or 99.5wt%; the mass percentage of the binder can be, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 4wt%, or 5wt%.

[0052] The negative electrode 3 and the positive electrode 1 with a solid electrolyte layer 2 on its surface are stacked or wound and the tabs are welded together to form a battery cell.

[0053] Specifically, the aforementioned cathode material includes one or more of lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), and lithium iron phosphate (LiFePO4).

[0054] Specifically, the aforementioned negative electrode material includes one or more of artificial graphite, natural graphite, silicon carbide, and metallic lithium.

[0055] Specifically, the aforementioned solid electrolyte includes Li 10 GeP2S 12 One or more of Li3PS4 and Li6PS5Cl.

[0056] Specifically, the conductive agent mentioned above includes one or more of carbon black, acetylene black, and carbon nanotubes (CNTs).

[0057] Specifically, the aforementioned adhesives include one or more of polyvinylidene fluoride, styrene-butadiene rubber, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, polyimide, polyethylene terephthalate, and polytetrafluoroethylene.

[0058] Specifically, the solvents mentioned above include one or more of N-methylpyrrolidone, toluene, xylene, anisole, tetrahydrofuran, dimethyltetrahydrofuran, cyclohexane, n-hexane, ethylene glycol dimethyl ether, and diisobutyl ketone.

[0059] In some embodiments, the raw material for the solid electrolyte layer includes Li 10 GeP2S 12 One or more of Li3PS4 and Li6PS5Cl.

[0060] It is understood that the raw materials for the aforementioned solid electrolyte layer may include Li. 10 GeP2S 12 Any one of Li3PS4 and Li6PS5Cl, or Li 10 GeP2S 12 Various arbitrary combinations of Li3PS4 and Li6PS5Cl.

[0061] In some more specific embodiments, the thickness of the polymer film is 50 μm to 100 μm. It is understood that the thickness of the polymer film can be, for example, 50 μm, 52 μm, 55 μm, 57 μm, 60 μm, 62 μm, 65 μm, 67 μm, 70 μm, 72 μm, 75 μm, 77 μm, 80 μm, 82 μm, 85 μm, 87 μm, 90 μm, 92 μm, 95 μm, 97 μm, or 100 μm, etc.

[0062] In some embodiments, the raw materials for the polymer film include one or more of propylene copolymers, SBS thermoplastic rubber, SEBS thermoplastic rubber, polyoxymethylene, polycarbonate, silicone, thermoplastic polyurethane, isobutylene rubber, and chloroprene rubber.

[0063] It is understood that the raw materials for polymer films can include any one of propylene copolymers, SBS thermoplastic rubber, SEBS thermoplastic rubber, polyoxymethylene, polycarbonate, silicone, thermoplastic polyurethane, isobutylene rubber, and chloroprene rubber, or any combination of at least two of propylene copolymers, SBS thermoplastic rubber, SEBS thermoplastic rubber, polyoxymethylene, polycarbonate, silicone, thermoplastic polyurethane, isobutylene rubber, and chloroprene rubber. The aforementioned polymer films are first prepared from these raw materials using methods such as screen printing or vapor deposition, and then produced through longitudinal stretching or biaxial stretching processes.

[0064] In some embodiments, the thickness of the polymer film is 20 μm to 100 μm. It should be noted that using a polymer film with a thickness of 20 μm to 100 μm is beneficial for winding the polymer film onto the surface of the battery cell, and a polymer film with a thickness of 20 μm to 100 μm is less prone to breakage. It is understood that the thickness of the polymer film can be any value between 20 μm and 100 μm, for example: 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 52 μm, 55 μm, 57 μm, 60 μm, 62 μm, 65 μm, 67 μm, 70 μm, 72 μm, 75 μm, 77 μm, 80 μm, 82 μm, 85 μm, 87 μm, 90 μm, 92 μm, 95 μm, 97 μm, or 100 μm, etc. In some more specific embodiments, the thickness of the polymer film is 50 μm to 100 μm.

[0065] In some embodiments, the winding tension is 20N to 100N. It should be noted that controlling the winding tension helps to tightly wrap the battery cell with the polymer film, thereby applying a certain constraint force to the positive and negative electrode sheets. It is understood that the winding tension can be any value between 20N and 100N, such as 20N, 30N, 40N, 50N, 60N, 70N, 80N, 90N, or 100N.

[0066] In some embodiments, the width of the polymer film is greater than or equal to the size of the cell in the direction perpendicular to the winding direction, so that the polymer film completely covers the surface of the cell to which it is attached.

[0067] It should be noted that the width of the polymer film is greater than or equal to the size of the battery cell in the direction perpendicular to the winding direction. In other words, the size of the battery cell in this direction does not protrude beyond the width of the polymer film. The polymer film can completely cover the positive electrode slurry layer of the positive electrode and the negative electrode slurry layer of the negative electrode. In other words, the polymer film can completely wrap the surfaces that adhere to the battery cell, which helps alleviate the expansion problem of the positive and negative electrodes during charging and discharging, thereby improving the cycle performance of the solid-state battery. When the width of the polymer film is equal to the size of the battery cell in the direction perpendicular to the winding direction, the edges of the polymer film will flow during the heat treatment of the battery cell wound with the polymer film. The resulting coating layer, formed after cooling and solidification, can still completely wrap the battery cell.

[0068] In some embodiments, the polymer film has 10 to 100 winding layers.

[0069] The thickness of the coating layer can be controlled by controlling the number of winding layers of the polymer film. The process is simple and suitable for large-scale production. It can be understood that the number of winding layers of the polymer film can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, or 100 layers, or other values ​​between 10 and 100 layers.

[0070] In some embodiments, the thickness of the coating layer is 1 mm to 5 mm.

[0071] The thickness of the coating layer varies, resulting in different levels of constraint on the positive and negative electrode sheets. The thickness of the coating layer can be selected based on the performance characteristics of the positive and negative electrode sheets. For example, the coating layer thickness can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm, and can also be other values ​​between 1mm and 5mm.

[0072] In some embodiments, the heat treatment process conditions include a heating temperature of 80°C to 190°C, a heating time of 2 min to 5 min, and a vacuum degree of -0.05 MPa to -0.1 MPa.

[0073] It should be noted that heat treatment under vacuum conditions is beneficial for eliminating air bubbles between the layers of the wound polymer film and for ensuring tight adhesion between the layers. The heating temperature can be, for example, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, or 190℃, and the heating time can be any value between 2 min and 5 min, for example: 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, or 5 min. The vacuum level can be, for example, -0.05 MPa, -0.06 MPa, -0.07 MPa, -0.08 MPa, -0.09 MPa, or -0.1 MPa.

[0074] In some implementations, the solid-state battery also includes a casing, with the battery cell and coating located inside the casing.

[0075] The aforementioned coating layer completely encapsulates the battery cell before placing it inside the casing. During the charging and discharging process of the solid-state battery, the elastic coating layer provides constraint on the battery cell, ensuring that the internal structure of the battery cell fits tightly and inhibiting the expansion of the battery cell, thereby improving the cycle life of the solid-state battery.

[0076] Another embodiment of this application provides a method for preparing the above-described solid-state battery, comprising the following steps:

[0077] Provide battery cells;

[0078] The polymer film is bonded to the surface of the battery cell and then wound multiple times.

[0079] The battery cell, which is wound with a polymer film, is heated to fuse the polymer film into a whole, and then cooled and cured to form a coating layer.

[0080] The thickness of the coating layer can be controlled by adjusting the thickness of the polymer film and the number of winding layers. After reaching the target coating layer thickness, heat treatment is used to fuse and shrink the polymer film into a whole. The resulting coating layer completely encapsulates the battery cell, effectively pressurizing it. Fusing the polymer film into a single unit helps ensure uniform stress on the cell, thereby improving the cycle life of the solid-state battery. During the charging and discharging process of the solid-state battery, the coating layer provides a certain elastic pressure to the cell, achieving a pressurizing effect without the need for external pressurization devices. This not only enhances the internal pressure of the solid-state battery, promotes material contact, effectively alleviates electrode expansion issues, and improves the cycle life of the solid-state battery, but also allows for precise control of the coating layer thickness without molds. This solves the problem of low production speed caused by limitations in the number, precision, and size of injection molds, providing a solution for increasing the production volume of solid-state lithium batteries.

[0081] In some embodiments, the method for preparing a solid-state battery further includes the following steps: placing a cell with a coating layer into a casing and encapsulating it under a vacuum of -0.05MPa to -0.1MPa, and then subjecting it to isostatic pressure treatment of 10MPa to 500MPa.

[0082] The encapsulation process is first performed under vacuum conditions. This is to prevent oxygen and moisture in the air from affecting the performance of the solid-state battery, and also to ensure a tighter fit between the cell, the coating layer, and the casing. The vacuum level can be any value between -0.05MPa and -0.1MPa, such as -0.05MPa, -0.06MPa, -0.07MPa, -0.08MPa, -0.09MPa, or -0.1MPa. The isostatic pressure treatment can be any value between 10MPa and 500MPa, such as 10MPa, 15MPa, 20MPa, 25MPa, 30MPa, 35MPa, 40MPa, 45MPa, 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, 100MPa, 200MPa, 300MPa, 400MPa, or 500MPa.

[0083] Another embodiment of this application provides an electrical device, including the solid-state battery described above or the solid-state battery prepared by the above preparation method.

[0084] The aforementioned electrical devices can use solid-state batteries as their power source or energy storage unit. These electrical devices include, but are not limited to, electric vehicles, mobile phones, computers, tablets, and smart home appliances.

[0085] The present application will be further described in detail below with reference to specific embodiments and comparative examples. The experimental materials used in the following embodiments and comparative examples of this application can be purchased commercially or prepared according to conventional methods well known to those skilled in the art.

[0086] Example 1

[0087] The method for manufacturing battery cells is as follows:

[0088] S1. Aluminum foil is selected as the positive electrode current collector, NCM622(LiNi) 0.6 Co 0.2 Mn 0.2 O2) as the positive electrode material, Li 10 GeP2S 12 As a solid electrolyte, acetylene black is used as a conductive agent, and polyacrylic acid is used as a binder. The positive electrode material, solid electrolyte, conductive agent and binder are mixed in a mass ratio of 84:13:2:1 to prepare a positive electrode slurry. The solvent of the positive electrode slurry is xylene, and the solid content of the positive electrode slurry is 60wt%. It is uniformly coated on aluminum foil to obtain a positive electrode sheet.

[0089] S2. The sulfide solid electrolyte Li 10 GeP2S 12 A slurry was prepared by mixing polyacrylic acid with a binder at a mass ratio of 98:2, using xylene as the solvent and having a solid content of 55 wt%. This slurry was then coated onto the surface of the positive electrode to form a solid electrolyte layer.

[0090] S3. Select copper foil as the negative electrode current collector and graphite as the negative electrode material, Li 10 GeP2S 12 As a solid electrolyte, carbon nanotubes are used as a conductive agent, and polyvinylidene fluoride is used as a binder. The negative electrode material, solid electrolyte, conductive agent and binder are prepared into a negative electrode slurry in a mass ratio of 75:15:8:2. The solvent of the negative electrode slurry is xylene, and the solid content of the negative electrode slurry is 55wt%. It is then uniformly coated on copper foil.

[0091] S4. Cut the positive and negative electrode sheets to the set size, stack them and weld the tabs to form a battery cell.

[0092] The preparation method of solid-state batteries is as follows:

[0093] Step 1: A 50μm thick propylene copolymer film is selected as the polymer film. The propylene copolymer film is prepared by screen printing and longitudinal stretching. The 50μm thick propylene copolymer film is tightly wound onto the battery cell for coating. The winding tension is 50N, and a total of 50 turns are wound, with a total winding length of approximately 4.75m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 150℃ and -0.1MPa for 2 minutes to achieve the effect of degassing, polymerization, and shrinkage of the propylene copolymer film, so that the battery cell is fully coated. After that, heating is stopped and the battery cell is allowed to cool naturally to room temperature to obtain a battery cell with a polymer coating layer. The coating layer thickness is 2.5mm.

[0094] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 300MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40mm×70mm electrode sheets.

[0095] Example 2

[0096] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0097] The preparation method of solid-state batteries is as follows:

[0098] Step 1: A 100μm thick SBS film is selected as the polymer film. The SBS film is prepared by screen printing and longitudinal stretching. The 100μm thick SBS film is tightly wound onto the battery cell for coating. The winding tension is 100N, and a total of 10 turns are wound, with a total winding length of about 0.9m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 150℃ and -0.1MPa for 3 minutes to achieve the effect of debubbling, polymerization, and shrinkage of the SBS film, so that the battery cell is fully coated. After that, the heating is stopped and the cell is naturally cooled to room temperature to obtain a battery cell with a polymer coating layer with a coating layer thickness of 1mm.

[0099] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 50MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0100] Example 3

[0101] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0102] The preparation method of solid-state batteries is as follows:

[0103] Step 1: A 50μm thick SEBS film is selected as the polymer film. The SEBS film is prepared by screen printing and longitudinal stretching. The 50μm thick SEBS film is tightly wound onto the battery cell for coating. The winding tension is 50N, and a total of 100 turns are wound, with a total winding length of about 10m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 250℃ and -0.1MPa for 3 minutes to achieve the effect of debubbling, polymerization, and shrinkage of the SEBS film, so that the battery cell is fully coated. After that, the heating is stopped and the cell is naturally cooled to room temperature to obtain a battery cell with a polymer coating layer with a coating layer thickness of 5mm.

[0104] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 300MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0105] Example 4

[0106] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0107] The preparation method of solid-state batteries is as follows:

[0108] Step 1: A 50μm thick polyoxymethylene (POM) film is selected as the polymer film. The POM film is prepared by screen printing and longitudinal stretching. The 50μm thick POM film is tightly wound onto the battery cell for coating. The winding tension is 50N, and a total of 50 turns are wound, with a total winding length of approximately 4.75m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 180℃ and -0.1MPa for 5 minutes to achieve the degassing, polymerization, and shrinkage of the POM film, so that the battery cell is fully coated. After that, heating is stopped and the cell is allowed to cool naturally to room temperature to obtain a battery cell with a polymer coating layer. The coating layer thickness is 2.5mm.

[0109] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 500MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0110] Example 5

[0111] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0112] The preparation method of solid-state batteries is as follows:

[0113] Step 1: A 50μm thick polycarbonate film is selected as the polymer film. The polycarbonate film is prepared by screen printing and longitudinal stretching. The 50μm thick polycarbonate film is tightly wound onto the battery cell for coating. The winding tension is 20N, and a total of 50 turns are wound, with a total winding length of approximately 4.75m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 120℃ and -0.1MPa for 3 minutes to achieve the effects of degassing, polymerization, and shrinkage of the polycarbonate film, so that the battery cell is fully coated. After that, heating is stopped and the cell is allowed to cool naturally to room temperature to obtain a battery cell with a polymer coating layer. The coating layer thickness is 2.5mm.

[0114] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 300MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0115] Example 6

[0116] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0117] The preparation method of solid-state batteries is as follows:

[0118] Step 1: A 50μm thick silicone film is selected as the polymer film. The silicone film is prepared by screen printing and longitudinal stretching. The 50μm thick silicone film is tightly wound onto the battery cell for coating. The winding tension is 80N, and a total of 50 turns are wound, with a total winding length of approximately 4.75m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 220℃ and -0.1MPa for 4 minutes to achieve the effect of debubbling, polymerization, and shrinkage of the silicone film, so that the battery cell is fully coated. After that, heating is stopped and the battery cell is allowed to cool naturally to room temperature to obtain a battery cell with a polymer coating layer. The coating layer thickness is 2.5mm.

[0119] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 300MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0120] Example 7

[0121] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0122] The preparation method of solid-state batteries is as follows:

[0123] Step 1: A 20μm thick propylene copolymer film is selected as the polymer film. The propylene copolymer film is prepared by screen printing and longitudinal stretching. The 20μm thick propylene copolymer film is tightly wound onto the battery cell for coating. The winding tension is 20N, and a total of 50 turns are wound, with a total winding length of approximately 4.75m. The coated battery cell is suspended in a vacuum oven through fixed tabs and heated at 150℃ and -0.1MPa for 2 minutes to achieve the degassing, polymerization, and shrinkage of the propylene copolymer film, so that the battery cell is fully coated. After that, heating is stopped and the battery cell is allowed to cool naturally to room temperature to obtain a battery cell with a polymer coating layer. The coating layer thickness is 1mm.

[0124] Step 2: Place the battery cell into an aluminum-plastic shell and encapsulate it at -0.1MPa. After encapsulation, perform isostatic pressing at 300MPa to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0125] Comparative Example 1

[0126] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0127] The preparation method of solid-state batteries is as follows:

[0128] Step 1: Place the battery cell into the injection mold and pour the propylene copolymer at 150℃ and -0.1MPa. After it completely covers the battery cell, apply a pressure of 20MPa and then slowly cool down to allow the propylene copolymer to solidify and form an elastic polymer coating layer. The thickness of the solidified elastic polymer coating layer is 10mm.

[0129] Step 2: Place the cured battery cell into an aluminum-plastic shell, place it in a stamping mold, and pressurize it under -0.1MPa and 300MPa conditions (i.e., isostatic pressing) and seal the edges to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0130] Comparative Example 2

[0131] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0132] The preparation method of solid-state batteries is as follows:

[0133] Step 1: Place the battery cell into the injection mold and pour SBS at 150℃ and -0.1MPa. After it completely covers the battery cell, apply 20MPa pressure and then slowly cool down to allow the SBS to solidify and form an elastic polymer coating layer. The thickness of the solidified elastic polymer coating layer is 1mm.

[0134] Step 2: Place the cured battery cell into an aluminum-plastic shell, place it in a stamping mold, pressurize it under -0.1MPa and 50MPa conditions (i.e., isostatic pressing), and seal the edges to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0135] Comparative Example 3

[0136] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0137] The preparation method of solid-state batteries is as follows:

[0138] Step 1: Place the battery cell into the injection mold and pour SEBS at 250℃ and -0.1MPa. After it completely covers the battery cell, apply a pressure of 20MPa and then slowly cool down to allow the SEBS to solidify and form an elastic polymer coating layer. The thickness of the solidified elastic polymer coating layer is 5mm.

[0139] Step 2: Place the cured battery cell into an aluminum-plastic shell, place it in a stamping mold, and pressurize it under -0.1MPa and 300MPa conditions (i.e., isostatic pressing) and seal the edges to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0140] Comparative Example 4

[0141] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0142] The preparation method of solid-state batteries is as follows:

[0143] Step 1: Place the battery cell into the injection mold and pour polyoxymethylene at 180℃ and -0.1MPa. After it completely covers the battery cell, apply pressure at 20MPa and then slowly cool down to allow the polyoxymethylene to solidify and form an elastic polymer coating layer. The thickness of the solidified elastic polymer coating layer is 2.5mm.

[0144] Step 2: Place the cured battery cell into an aluminum-plastic shell, put it into a stamping mold, pressurize it under -0.1MPa and 500MPa conditions (i.e., isostatic pressing), and seal the edges to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0145] Comparative Example 5

[0146] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0147] The preparation method of solid-state batteries is as follows:

[0148] Step 1: Place the battery cell into the injection mold and pour polycarbonate at 120℃ and -0.1MPa. After it completely covers the battery cell, apply a pressure of 20MPa and then slowly cool down to allow the polycarbonate to solidify and form an elastic polymer coating layer. The thickness of the solidified elastic polymer coating layer is 2.5mm.

[0149] Step 2: Place the cured battery cell into an aluminum-plastic shell, place it in a stamping mold, and pressurize it under -0.1MPa and 300MPa conditions (i.e., isostatic pressing) and seal the edges to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0150] Comparative Example 6

[0151] The method for preparing the battery cell and the battery cell used are the same as in Example 1.

[0152] The preparation method of solid-state batteries is as follows:

[0153] Step 1: Place the battery cell into the injection mold and pour silicone at 220℃ and -0.1MPa. After the silicone completely covers the battery cell, apply pressure at 20MPa and then slowly cool down to allow the silicone to solidify and form an elastic polymer coating layer. The thickness of the solidified elastic polymer coating layer is 2.5mm.

[0154] Step 2: Place the cured battery cell into an aluminum-plastic shell, place it in a stamping mold, and pressurize it under -0.1MPa and 300MPa conditions (i.e., isostatic pressing) and seal the edges to obtain a solid-state battery. The solid-state battery is a stacked soft-pack battery including 40×70mm electrode sheets.

[0155] Performance testing

[0156] The solid-state batteries prepared in Examples 1-7 and Comparative Examples 1-6 were subjected to a 0.1C charge-discharge cycle test at 45°C. The number of cycles was recorded. Using the discharge capacity of the 5th cycle as a baseline, the capacity retention rate after 100 cycles was calculated as (discharge capacity after 100 cycles / discharge capacity after 5 cycles) × 100%. The test results are shown in Table 1 and... Figures 5-11 As shown.

[0157] Figure 3 This is a cross-sectional view of the solid-state battery cell in Example 1 after 100 cycles. Figure 4 This is a cross-sectional view of the solid-state battery cell in Comparative Example 1 after 100 cycles. Figure 3 It can be seen that after 100 cycles, the coating layer of Example 1 showed no significant change, remaining tightly bonded to the positive and negative electrode sheets, which maintained their layered structure without significant bending deformation. Figure 4It can be seen that the cross-section of the coating layer in Comparative Example 1 is white and shows a tendency to become brittle. The positive and negative electrode sheets in Comparative Example 1 no longer have obvious layered structures and have undergone bending deformation. This indicates that although the coating layer in Comparative Example 1 is thicker, the coating layer in Example 1 can provide stronger voltage holding capacity for the cell, which is more conducive to improving the cycle life of the solid-state battery.

[0158] Table 1. Capacity retention of solid-state batteries in Examples 1-7 and Comparative Examples 1-6 after 100 cycles.

[0159]

[0160]

[0161] Combining Table 1 and Figures 5-10 Compared with the coating layer of Example 1, the coating layer of Comparative Example 1 is thicker; however, the capacity retention rate of the solid-state battery of Comparative Example 1 after 100 cycles is much lower than that of Example 1.

[0162] The coating layer of Example 2 has the same thickness as that of Comparative Example 2, and the capacity retention rate of the solid-state battery of Example 2 after 100 cycles is much higher than that of Comparative Example 2.

[0163] The coating layer of Example 3 has the same thickness as that of Comparative Example 3, and the capacity retention rate of the solid-state battery of Example 3 after 100 cycles is significantly higher than that of Comparative Example 3.

[0164] The coating layer of Example 4 has the same thickness as that of Comparative Example 4, and the capacity retention of the solid-state battery of Example 4 after 100 cycles is significantly better than that of Comparative Example 4.

[0165] The coating layer of Example 5 has the same thickness as that of Comparative Example 5, and the capacity retention rate of the solid-state battery of Example 5 after 100 cycles is significantly better than that of Comparative Example 5.

[0166] The coating layer of Example 6 has the same thickness as that of Comparative Example 6, and the capacity retention rate of the solid-state battery of Example 6 after 100 cycles is much higher than that of Comparative Example 6.

[0167] Combining Table 1 and Figure 11In Example 7, the coating thickness was 1 mm, and the capacity retention rate after 100 cycles was 79.6%. A propylene copolymer was cast onto the cell surface using the same method as in Comparative Example 1 to form an elastic polymer coating layer, resulting in a cured elastic polymer coating layer thickness of 1 mm. However, due to the thinness of the elastic polymer coating layer, its preparation is difficult, and the thickness accuracy of the prepared coating layer and the positional accuracy of the cell within it are poor, making it difficult to achieve a cured elastic polymer coating layer thickness of 1 mm. This demonstrates that the solid-state battery provided by this application can precisely control the coating layer thickness without a mold, alleviating the problem of electrode sheet expansion and facilitating mass production of solid-state batteries.

[0168] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0169] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A solid-state battery, characterized in that, The solid-state battery includes a cell and a coating layer covering the surface of the cell; The battery cell includes a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode; The coating layer completely encapsulates the battery cell. The coating layer is formed by heating and fusing multiple polymer films bonded and wound onto the surface of the battery cell, then curing the resulting composite material to provide thickness-direction constraint on the positive and negative electrode plates. The winding tension is 20N~100N. The raw materials of the polymer film include one or more of propylene copolymer, SBS thermoplastic rubber, SEBS thermoplastic rubber, polyoxymethylene, polycarbonate, silicone, thermoplastic polyurethane, isobutylene rubber, and neoprene rubber. The number of winding layers of the polymer film is 10~100 layers. The thickness of the coating layer is 1mm~5mm. The heat treatment process conditions include a heating temperature of 80℃~190℃, a heating time of 2min~5min, and a vacuum degree of -0.05MPa~-0.1MPa.

2. The solid-state battery according to claim 1, characterized in that, The raw material for the polymer film is a propylene copolymer.

3. The solid-state battery according to any one of claims 1 to 2, characterized in that, The thickness of the polymer film is 20μm to 100μm.

4. The solid-state battery according to claim 1, characterized in that, The raw material for the solid electrolyte layer includes Li 10 GeP2S 12 One or more of Li3PS4 and Li6PS5Cl.

5. The solid-state battery according to claim 1, characterized in that, The width of the polymer film is greater than or equal to the size of the battery cell in the direction perpendicular to the winding direction, so that the polymer film completely covers the surface of the battery cell to which it is attached.

6. The solid-state battery according to claim 1, characterized in that, The polymer film has 50 to 100 winding layers.

7. The solid-state battery according to claim 1, characterized in that, The thickness of the coating layer is 1mm to 2.5mm.

8. The solid-state battery according to any one of claims 1-2 and 4-7, characterized in that, It also includes a housing, with the battery cell and the cladding layer located inside the housing.

9. The method for preparing a solid-state battery according to any one of claims 1 to 8, characterized in that, Includes the following steps: Provide the battery cell; The polymer film is bonded to the surface of the battery cell and wound multiple times. The battery cell, which is wound around the polymer film, is subjected to the heat treatment to fuse the polymer film into a whole, and then cooled and solidified to form the coating layer.

10. The preparation method according to claim 9, characterized in that, It also includes the following steps: The battery cell with the coating layer is placed in a housing and encapsulated under a vacuum of -0.05MPa to -0.1MPa, and then subjected to isostatic pressure treatment of 10MPa to 500MPa.

11. An electrical appliance, characterized in that, This includes the solid-state battery as described in any one of claims 1 to 8 or the solid-state battery prepared by the preparation method described in any one of claims 9 to 10.

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