All-solid-state battery and preparation method thereof

Abstract

The invention discloses an all-solid-state battery and a preparation method thereof.The preparation method comprises the steps that a negative electrode piece and a first electrolyte membrane are subjected to first pressing treatment to obtain a composite negative electrode, and the first pressing treatment comprises the steps that the negative electrode piece is subjected to first pressing treatment; performing second pressure treatment on the first electrolyte membrane; oppositely arranging the negative pole piece subjected to the first pressure applying treatment and the first electrolyte membrane subjected to the second pressure applying treatment, and performing third pressure applying treatment to obtain a preformed composite negative pole; carrying out n1 fourth pressing treatment on the preformed composite negative electrode (1 < = n1 < = 10) to obtain a composite negative electrode; carrying out second pressing treatment on the positive pole piece to obtain a composite positive pole; and arranging the side, provided with the first electrolyte membrane, of the composite negative electrode opposite to the composite positive electrode, and performing third pressing treatment to obtain the all-solid-state battery. Therefore, the production efficiency of the all-solid-state battery is improved, the cost is reduced, and the battery has better cycle performance and rate capability.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, specifically to all-solid-state batteries and their fabrication methods. Background Technology

[0002] The current fabrication process for all-solid-state batteries includes steps such as electrode preparation, negative electrode and electrolyte layer bonding, negative electrode edge modification, stacking, encapsulation, and isostatic pressing. However, the aforementioned fabrication method requires an isostatic pressing step, and current isostatic pressing equipment is expensive, the pressing process is time-consuming, and it is difficult to press multiple cells in a batch, thus hindering mass production. Therefore, the fabrication of all-solid-state batteries requires further improvement.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of this application, a method for preparing an all-solid-state battery is proposed, comprising: subjecting a negative electrode sheet and a first electrolyte membrane to a first pressing process to obtain a composite negative electrode, wherein the first pressing process includes: subjecting the negative electrode sheet to a first pressure treatment; subjecting the first electrolyte membrane to a second pressure treatment; placing the negative electrode sheet after the first pressure treatment and the first electrolyte membrane after the second pressure treatment opposite to each other, and subjecting them to a third pressure treatment to obtain a pre-formed composite negative electrode; subjecting the pre-formed composite negative electrode to n1 fourth pressure treatments, where 1≤n1≤10, to obtain the composite negative electrode; subjecting a positive electrode sheet to a second pressing process to obtain a composite positive electrode; placing the side of the composite negative electrode with the first electrolyte membrane opposite to the composite positive electrode, and subjecting it to a third pressing process to obtain the all-solid-state battery. This method is beneficial for improving the production efficiency of all-solid-state batteries, reducing costs, and providing the battery with better cycle performance and rate performance.

[0005] In some embodiments, the pressure of the first pressure treatment is 10MPa-20MPa, and the temperature range is 20℃-100℃. This is beneficial for increasing the compaction density of the negative electrode sheet, thereby increasing the volumetric energy density of the negative electrode sheet, while also giving it high mechanical strength so as to maintain structural integrity in subsequent processes.

[0006] In some embodiments, the pressure of the second pressure treatment is 5 MPa-10 MPa, and the temperature range is 20°C-100°C. This helps to increase the density of the first electrolyte membrane, forming continuous ion transport channels within it, thereby improving ionic conductivity and providing a foundation for the rate performance of all-solid-state batteries.

[0007] In some embodiments, the pressure of the third pressure treatment is 10 MPa-20 MPa, and the temperature range is 20°C-100°C; and / or, the pressure of the fourth pressure treatment is 20 MPa-100 MPa, and the temperature range is 20°C-100°C. This facilitates a tighter interface bonding between the negative electrode and the first electrolyte membrane, improving the density of the composite negative electrode.

[0008] In some embodiments, the porosity of the negative electrode sheet after the first pressure treatment is 20%-30%; and / or, the porosity of the first electrolyte membrane after the second pressure treatment is 40%-50%; and / or, after the third pressure treatment, the porosity of the first electrolyte membrane in the preformed composite negative electrode is 20%-30%; and / or, after the n1th fourth pressure treatment, the porosity of the composite negative electrode is less than or equal to 10%. This facilitates shortening the ion transport path, improving ion conductivity, and reducing the contact resistance at the interface between the composite negative electrode and the first electrolyte membrane.

[0009] In some embodiments, 4 ≤ n1 ≤ 8. This helps to reduce the number of processes and improve production efficiency.

[0010] In some embodiments, the second pressing process includes: applying a fifth pressing process to the positive electrode sheet to obtain a pre-formed composite positive electrode; and applying an eighth pressing process n² times to the pre-formed composite positive electrode, where 1 ≤ n² ≤ 10, to obtain a composite positive electrode. This facilitates the construction of continuous ion and electron transport channels and reduces the electron transport impedance within the positive electrode sheet.

[0011] In some embodiments, the second pressing process further includes: applying a sixth pressing treatment to the second electrolyte membrane; placing the positive electrode sheet after the fifth pressing treatment and the second electrolyte membrane after the sixth pressing treatment opposite each other, and then applying a seventh pressing treatment to obtain a pre-formed composite positive electrode. This increases the physical contact area between the positive electrode sheet and the second electrolyte membrane, resulting in a tighter bond between them, lower interfacial porosity, and thus significantly reduced interfacial ion transport resistance. Simultaneously, it helps to form a mechanical interlock between the positive electrode sheet and the second electrolyte membrane, effectively resisting interfacial peeling caused by cyclic stress and maintaining long-term structural integrity.

[0012] In some embodiments, the pressure of the fifth pressure treatment is 20MPa-40MPa, and the temperature range is 20℃-100℃. This is beneficial for increasing the compaction density of the positive electrode sheet, making the positive electrode active material layer and the positive electrode current collector more firmly bonded, and also improving the mechanical strength and flexibility of the positive electrode sheet.

[0013] In some embodiments, the pressure of the sixth pressure treatment is 5 MPa-10 MPa, and the temperature range is 20℃-100℃. This helps to eliminate porosity between solid electrolyte particles, reduce grain boundary transport resistance of ions, achieve atomic-level bonding and densification between particles, and improve ion transport rate.

[0014] In some embodiments, the pressure of the seventh pressure treatment is 10 MPa-20 MPa, and the temperature range is 20°C-100°C; and / or, the pressure of the eighth pressure treatment is 40 MPa-80 MPa, and the temperature range is 20°C-100°C. This facilitates interfacial diffusion and bonding between the positive electrode and the second electrolyte membrane, reducing the porosity of the composite positive electrode.

[0015] In some embodiments, the porosity of the positive electrode sheet after the fifth pressure treatment is 20%-30%; and / or, the porosity of the second electrolyte membrane after the sixth pressure treatment is 40%-50%; and / or, after the seventh pressure treatment, the porosity of the second electrolyte membrane in the preformed composite positive electrode is 20%-30%; and / or, after the n2th eighth pressure treatment, the porosity of the composite positive electrode is less than or equal to 10%. This facilitates shortening the ion transport path, improving ion conductivity, and reducing the interfacial contact resistance between the composite positive electrode and the second electrolyte membrane.

[0016] In some embodiments, 4 ≤ n² ≤ 8. This helps to reduce the number of processes and improve production efficiency.

[0017] In some embodiments, the pressure of the third pressing process is 20MPa-40MPa, and the temperature range is 20℃-100℃. This improves the contact between the solid-solid interface of the first and second electrolyte membranes, reduces interfacial resistance, and achieves integrated molding.

[0018] In some embodiments, the first electrolyte membrane comprises a sulfide electrolyte, wherein the sulfide electrolyte includes a steric sulfide-germanium ore type electrolyte, Li3PS4, or Li6PS5Cl. 1-x Br x At least one of the following; and / or, the second electrolyte membrane comprises a halide electrolyte, wherein the halide electrolyte comprises at least one of Li₂InCl₆ and Li₂ZrCl₆. This is beneficial for improving the high-voltage performance and cycle stability of all-solid-state batteries.

[0019] In a second aspect of this application, an all-solid-state battery is proposed, which is prepared using the method described in the first aspect of this application. Therefore, this all-solid-state battery exhibits good cycle performance and rate performance. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein, Figure 1 This is a flowchart illustrating the fabrication process of an all-solid-state battery according to an embodiment of this application. Detailed Implementation

[0021] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0023] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0024] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0025] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of that feature.

[0027] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0028] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0029] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0030] In the first aspect of this application, a method for preparing all-solid-state batteries is proposed. This method has high production efficiency, low cost, and produces all-solid-state batteries with good cycle performance and rate performance. Specifically, refer to... Figure 1 The method includes: S1: The negative electrode sheet and the first electrolyte membrane are subjected to a first pressing process to obtain the composite negative electrode A.

[0031] The first pressing process includes: applying a first pressing treatment to the negative electrode sheet; applying a second pressing treatment to the first electrolyte membrane; placing the negative electrode sheet after the first pressing treatment and the first electrolyte membrane after the second pressing treatment opposite to each other, and applying a third pressing treatment to obtain a pre-formed composite negative electrode; and applying a fourth pressing treatment n1 times to the pre-formed composite negative electrode, where 1≤n1≤10, to obtain the composite negative electrode.

[0032] As an example, n1 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, etc.

[0033] In some embodiments, the pressure of the first pressure treatment is 10MPa-20MPa (e.g., 10MPa, 12MPa, 14MPa, 16MPa, 18MPa, or 20MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-80℃. This is beneficial for increasing the compaction density of the negative electrode sheet, thereby increasing the volumetric energy density of the negative electrode sheet, while also giving it high mechanical strength to maintain structural integrity in subsequent processes.

[0034] In some embodiments, the pressure of the second pressure treatment is 5 MPa-10 MPa (e.g., 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa), and the temperature range is 20°C-100°C (e.g., 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C); optionally, the temperature range is 60°C-80°C. This helps to improve the density of the first electrolyte membrane, forming continuous ion transport channels within it, thereby improving ionic conductivity and providing a basis for the rate performance of all-solid-state batteries.

[0035] It should be noted that the pressure of the second pressure treatment must not exceed the given maximum value, in order to prevent the porosity of the first electrolyte membrane from decreasing excessively in advance, which would prevent the completion of subsequent composite processes (i.e., the third pressure treatment, the fourth pressure treatment, and the third pressing treatment).

[0036] In some embodiments, the pressure of the third pressure treatment is 10MPa-20MPa (e.g., 10MPa, 12MPa, 14MPa, 16MPa, 18MPa, or 20MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-100℃; and / or, the fourth pressure treatment... The pressure for the pressure treatment is 20MPa-100MPa (e.g., 20MPa, 30MPa, 40MPa, 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, or 100MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-80℃. This facilitates a tighter interface bonding between the negative electrode and the first electrolyte membrane, improving the density of the composite negative electrode.

[0037] It should be noted that the pressure of the fourth pressure treatment varies depending on the negative electrode active material used. For example, when the negative electrode active material is porous silicon-carbon or alloy silicon, the pressure of the fourth pressure treatment can be 20MPa-40MPa. When the negative electrode active material is micron-sized silicon, graphite, or hard carbon, the pressure of the fourth pressure treatment can be 60MPa-100MPa.

[0038] In some embodiments, the porosity of the negative electrode sheet after the first pressure treatment is 20%-30%, for example, it can be 20%, 22%, 24%, 26%, 28%, or 30%; and / or, the porosity of the first electrolyte membrane after the second pressure treatment is 40%-50%, for example, it can be 40%, 42%, 44%, 46%, 48%, or 50%; and / or, after the third pressure treatment, the porosity of the first electrolyte membrane in the preformed composite negative electrode is 20%-30%, for example, it can be 20%, 22%, 24%, 26%, 28%, or 30%; and / or, after the n1th fourth pressure treatment, the porosity of the composite negative electrode is less than or equal to 10%, for example, it can be 1%, 2%, 4%, 6%, 8%, or 10%. This is beneficial for shortening the ion transport path, improving ion conductivity, and reducing the contact resistance at the interface between the composite negative electrode and the first electrolyte membrane.

[0039] In some embodiments, 4 ≤ n1 ≤ 8. This helps to reduce the number of processes and improve production efficiency.

[0040] In some embodiments, the first electrolyte membrane comprises a negatively stable sulfide electrolyte, wherein the sulfide electrolyte comprises a steric sulfide-germanium ore type electrolyte, Li3PS4, or Li6PS5Cl. 1-x Br xAt least one of (LPSCB). This is beneficial for improving the high-voltage performance and cycle stability of all-solid-state batteries.

[0041] S2: Perform a second pressing process on the positive electrode sheet to obtain composite positive electrode B.

[0042] In some embodiments, the second pressing process includes: applying a fifth pressing process to the positive electrode sheet to obtain a pre-formed composite positive electrode; and applying an eighth pressing process n² times to the pre-formed composite positive electrode, where 1 ≤ n² ≤ 10, to obtain a composite positive electrode. This facilitates the construction of continuous ion and electron transport channels and reduces the electron transport impedance within the positive electrode sheet.

[0043] As an example, n2 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, etc.

[0044] In some embodiments, the second pressing process further includes: applying a sixth pressing treatment to the second electrolyte membrane; placing the positive electrode sheet after the fifth pressing treatment and the second electrolyte membrane after the sixth pressing treatment opposite each other, and then applying a seventh pressing treatment to obtain a pre-formed composite positive electrode. This increases the physical contact area between the positive electrode sheet and the second electrolyte membrane, resulting in a tighter bond between them, lower interfacial porosity, and thus significantly reduced interfacial ion transport resistance. Simultaneously, it helps to form a mechanical interlock between the positive electrode sheet and the second electrolyte membrane, effectively resisting interfacial peeling caused by cyclic stress and maintaining long-term structural integrity.

[0045] It is understood that those skilled in the art can flexibly choose whether or not to provide a second electrolyte membrane in the composite cathode according to specific circumstances.

[0046] In some embodiments, the pressure of the fifth pressure treatment is 20MPa-40MPa (e.g., 20MPa, 25MPa, 30MPa, 35MPa, or 40MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-80℃. This is beneficial for increasing the compaction density of the positive electrode sheet, making the positive electrode active material layer more firmly bonded to the positive electrode current collector, and also improving the mechanical strength and flexibility of the positive electrode sheet.

[0047] In some embodiments, the pressure of the sixth pressure treatment is 5MPa-10MPa (e.g., 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, or 10MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-80℃. This helps to eliminate porosity between solid electrolyte particles, reduce grain boundary transport resistance of ions, achieve atomic-level bonding and densification between particles, and improve ion transport rate.

[0048] It should be noted that the pressure of the sixth pressure treatment cannot exceed the given maximum value, because if the maximum value is exceeded, the porosity of the second electrolyte membrane will decrease prematurely, making it impossible to complete the subsequent composite process (i.e., the seventh pressure treatment, the eighth pressure treatment, and the third pressing treatment).

[0049] In some embodiments, the pressure of the seventh pressure treatment is 10MPa-20MPa (e.g., 10MPa, 12MPa, 14MPa, 16MPa, 18MPa, or 20MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-100℃; and / or, the pressure of the eighth pressure treatment is 40MPa-80MPa (e.g., 40MPa, 50MPa, 60MPa, 70MPa, or 80MPa), and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-80℃. This facilitates the interfacial diffusion and bonding between the positive electrode and the second electrolyte membrane, thereby reducing the porosity of the composite positive electrode.

[0050] In some embodiments, the porosity of the positive electrode sheet after the fifth pressure treatment is 20%-30%, for example, it can be 20%, 22%, 24%, 26%, 28%, or 30%; and / or, the porosity of the second electrolyte membrane after the sixth pressure treatment is 40%-50%, for example, it can be 40%, 42%, 44%, 46%, 48%, or 50%; and / or, after the seventh pressure treatment, the porosity of the second electrolyte membrane in the preformed composite positive electrode is 20%-30%, for example, it can be 20%, 22%, 24%, 26%, 28%, or 30%; and / or, after the n2th eighth pressure treatment, the porosity of the composite positive electrode is less than or equal to 10%, for example, it can be 1%, 2%, 4%, 6%, 8%, or 10%. This is beneficial for shortening the ion transport path, improving ion conductivity, and reducing the interfacial contact resistance between the composite positive electrode and the second electrolyte membrane.

[0051] In some embodiments, 4 ≤ n² ≤ 8. This helps to reduce the number of processes and improve production efficiency.

[0052] In some embodiments, the second electrolyte membrane comprises a halide electrolyte with a high electrochemical window, wherein the halide electrolyte comprises at least one of Li₂InCl₆ and Li₂ZrCl₆. This is beneficial for improving the high-voltage performance and cycle stability of all-solid-state batteries.

[0053] S3: The side of the composite negative electrode with the first electrolyte membrane is positioned opposite to the composite positive electrode, and a third pressing process is performed to obtain the all-solid-state battery.

[0054] In some embodiments, the pressure of the third pressing treatment is 20MPa-40MPa (e.g., 20MPa, 25MPa, 30MPa, 35MPa, or 40MPa), that is, the minimum value of the pressure values ​​of the fourth and eighth pressing treatments, and the temperature range is 20℃-100℃ (e.g., 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃); optionally, the temperature range is 60℃-80℃. This facilitates improved contact at the solid-solid interface between the first and second electrolyte membranes, reduces interface resistance, and achieves integrated molding.

[0055] In some embodiments, the side of the composite negative electrode with the first electrolyte membrane is positioned opposite the composite positive electrode, and a third pressing process is performed to obtain the composite unit C. In practical use, to improve capacity and voltage, multiple composite units can be stacked and vacuum-sealed to assemble an all-solid-state battery. The composite unit C can undergo electrochemical screening before stacking, such as testing parameters like open-circuit voltage and impedance, to further improve the consistency and yield of the all-solid-state battery.

[0056] The preparation method described in this application can achieve optimal density of the positive electrode, negative electrode, and electrolyte membrane under their respective required conditions, so that all three are in the most ideal working state at the same time. This effectively reduces the occurrence of overpressure or lack of density in one of the positive electrode, electrolyte membrane, or negative electrode structures, which is prone to occur when using an isostatic pressing integrated molding scheme.

[0057] In a second aspect of this application, an all-solid-state battery is proposed, which is prepared using the method described in the first aspect of this application. Therefore, this all-solid-state battery exhibits good cycle performance and rate performance.

[0058] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0059] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0060] Preparation of positive electrode plate B1: Using nickel-cobalt-manganese ternary material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) was used as the positive electrode active material. NCM811, electrolyte Li6PS5Cl, conductive agent CNT, and binder SBR were mixed in a mass ratio of 85:12:1:2 and diluted with an appropriate amount of xylene solvent. After being dispersed evenly, a positive electrode slurry (solid content of 70%) was obtained. The positive electrode slurry was coated on one side of an aluminum foil with a thickness of 12μm to obtain the positive electrode B1.

[0061] Preparation of negative electrode plate A1: Using porous silicon carbon as the negative electrode active material, porous silicon carbon, electrolyte Li6PS5Cl, conductive agent VGCF, and binder SBR are mixed in a mass ratio of 80:17:1:2, diluted with an appropriate amount of xylene solvent, and dispersed evenly to obtain a negative electrode slurry (solid content of 60%). The negative electrode slurry is coated on one side of a copper foil with a thickness of 6μm to obtain the negative electrode sheet A1.

[0062] Preparation of negative electrode plate A2: Micron-sized silicon and graphite in a mass ratio of 3:1 were used as negative electrode active materials. The negative electrode active materials, electrolyte Li6PS5Cl, conductive agent VGCF, and binder SBR were mixed in a mass ratio of 80:17:1:2 and diluted with an appropriate amount of xylene solvent. After uniform dispersion, a negative electrode slurry (solid content of 60%) was obtained. The negative electrode slurry was coated on one side of a copper foil with a thickness of 6μm to obtain negative electrode A2.

[0063] Preparation of the first electrolyte membrane S1: The electrolyte material LPSCB and the binder SBR are mixed at a mass ratio of 98:2, diluted with an appropriate amount of xylene solvent, and dispersed evenly to obtain a slurry (solid content of 60%). The prepared slurry is coated and dried to obtain the first electrolyte membrane S1.

[0064] Preparation of the second electrolyte membrane S2: The electrolyte material Li2InCl6 and the binder SBR were mixed at a mass ratio of 98:2, diluted with an appropriate amount of xylene solvent, and dispersed evenly to obtain a slurry (solid content of 60%). The prepared slurry was coated and dried to obtain the second electrolyte membrane S2.

[0065] Example 1 (1) Apply the first pressure treatment to the negative electrode plate A1; The first electrolyte membrane S1 is subjected to a second pressure treatment; The negative electrode A1 after the first pressure treatment is placed opposite to the first electrolyte membrane S1 after the second pressure treatment, and a third pressure treatment is performed to obtain a pre-formed composite negative electrode. The preformed composite negative electrode was subjected to four fourth pressure treatments to obtain the composite negative electrode.

[0066] (2) Apply the fifth pressure treatment to the positive electrode plate B1; The second electrolyte membrane S2 is subjected to a sixth pressure treatment; The positive electrode sheet after the fifth pressure treatment is placed opposite to the second electrolyte membrane after the sixth pressure treatment, and a seventh pressure treatment is performed to obtain a pre-formed composite positive electrode. The preformed composite cathode was subjected to four eighth pressure treatments to obtain the composite cathode.

[0067] (3) The side of the composite negative electrode with the first electrolyte membrane is arranged opposite to the side of the composite positive electrode with the second electrolyte membrane, and a third pressing process is performed to obtain a composite unit. The composite units are stacked and packaged to obtain an all-solid-state battery.

[0068] The differences between Examples 2-5 and Example 1 are shown in Table 1-1.

[0069] Table 1-1

[0070] Example 6 (1) Apply the first pressure treatment to the negative electrode plate A2; The first electrolyte membrane S1 is subjected to a second pressure treatment; The negative electrode A1 after the first pressure treatment is placed opposite to the first electrolyte membrane S1 after the second pressure treatment, and a third pressure treatment is performed to obtain a pre-formed composite negative electrode. The preformed composite negative electrode was subjected to four fourth pressure treatments to obtain the composite negative electrode.

[0071] (2) The positive electrode plate B1 is subjected to a fifth pressure treatment to obtain a pre-formed composite positive electrode; The preformed composite cathode was subjected to four eighth pressure treatments to obtain the composite cathode.

[0072] (3) The side of the composite negative electrode with the first electrolyte membrane is placed opposite the composite positive electrode and subjected to a third pressing process to obtain a composite unit. The composite units are stacked and sealed to obtain an all-solid-state battery.

[0073] The differences between Examples 7-10 and Example 6 are shown in Table 1-2.

[0074] Table 1-2

[0075] Comparative Example 1 A solid-state battery is obtained by sequentially stacking the negative electrode A1, the first electrolyte membrane S1, the second electrolyte membrane S2, and the positive electrode B1, sealing them, and pressing them through a 500MPa isostatic pressing process.

[0076] Comparative Example 2 A solid-state battery is obtained by sequentially stacking the negative electrode A1, the first electrolyte membrane S1, the second electrolyte membrane S2, and the positive electrode B1, sealing them, and pressing them through a 300MPa isostatic pressing process.

[0077] Comparative Example 3 After the negative electrode A2, the first electrolyte membrane S1, and the positive electrode B1 are stacked in sequence, they are sealed and pressed by a 500MPa isostatic pressing process to obtain an all-solid-state battery.

[0078] Comparative Example 4 After the negative electrode A2, the first electrolyte membrane S1, and the positive electrode B1 are stacked in sequence, they are sealed and pressed by a 300MPa isostatic pressing process to obtain an all-solid-state battery.

[0079] The porosity of the electrolyte membranes and electrodes prepared in all the above embodiments and comparative examples was tested. The test methods are as follows, and the test results are shown in Tables 2-1, 2-2, 2-3 and 2-4.

[0080] (1) Cut an electrode sample of a certain area S, measure its thickness and mass, and calculate the apparent density of the coating (or the compacted density of the coating):

[0081] (2) Calculate the average density of the coating based on the electrode ratio:

[0082] (3) The porosity calculation method is as follows:

[0083] It is understandable that the testing method for electrolyte membrane porosity is the same as that for electrode porosity.

[0084] Table 2-1 Electrode porosity values ​​during the first to eighth pressure treatments in Examples 1-5

[0085] Table 2-2 Electrode porosity values ​​during the first to eighth pressure treatments in Example 6-10

[0086] Table 2-3

[0087] Table 2-4

[0088] It should be noted that Tables 2-3 and 2-4 contain porosity data for the composite negative electrode, the first electrolyte membrane S1, the second electrolyte membrane S2, and the composite positive electrode in the final all-solid-state battery.

[0089] Rate performance and cycle performance tests were conducted on all solid-state batteries prepared in the above embodiments and comparative examples of this application. The rate performance test conditions were 2 MPa and 60°C, and the cycle performance test conditions were 5 MPa and 30°C, with a voltage range of 2.5V-4.25V, for 300 cycles. The capacity retention rate was measured. The test results are shown in Table 3. In the table, " / " indicates a short circuit.

[0090] Table 3

[0091] As can be seen from Table 3, the preparation method of the all-solid-state battery provided in this application can replace the process flow of the medium static pressure of the all-solid-state battery, improve production efficiency and reduce cost, and the all-solid-state battery has better cycle performance and rate performance.

[0092] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing an all-solid-state battery, characterized in that, include: The negative electrode sheet and the first electrolyte membrane are subjected to a first pressing process to obtain a composite negative electrode, wherein the first pressing process includes: The negative electrode sheet is subjected to a first pressure treatment; The first electrolyte membrane is subjected to a second pressure treatment; The negative electrode sheet after the first pressure treatment is placed opposite to the first electrolyte membrane after the second pressure treatment, and a third pressure treatment is performed to obtain a pre-formed composite negative electrode. The preformed composite negative electrode is subjected to n1 fourth pressure treatments, where 1≤n1≤10, to obtain the composite negative electrode; The positive electrode sheet is subjected to a second pressing process to obtain a composite positive electrode; The composite negative electrode with the first electrolyte membrane on one side is positioned opposite the composite positive electrode, and a third pressing process is performed to obtain the all-solid-state battery.

2. The method according to claim 1, characterized in that, The first pressure treatment is applied at a pressure of 10MPa-20MPa, with a temperature range of 20℃-100℃; and / or, The second pressure treatment involves a pressure of 5 MPa-10 MPa and a temperature range of 20℃-100℃; and / or, The third pressure treatment involves a pressure of 10MPa-20MPa and a temperature range of 20℃-100℃; and / or, The pressure for the fourth pressure treatment is 20MPa-100MPa, and the temperature range is 20℃-100℃.

3. The method according to claim 2, characterized in that, The porosity of the negative electrode sheet after the first pressure treatment is 20%-30%; and / or, The porosity of the first electrolyte membrane after the second pressure treatment is 40%-50%; and / or, After the third pressure treatment, the porosity of the first electrolyte membrane in the preformed composite negative electrode is 20%-30%; and / or, After the n1th fourth pressure treatment, the porosity of the composite negative electrode is less than or equal to 10%.

4. The method according to claim 1, characterized in that, 4≤n1≤8。 5. The method according to claim 1, characterized in that, The second pressing process includes: The positive electrode sheet is subjected to a fifth pressure treatment to obtain a pre-formed composite positive electrode; The preformed composite cathode is subjected to n2 eighth pressure treatments, where 1≤n2≤10, to obtain the composite cathode.

6. The method according to claim 5, characterized in that, The second suppression process also includes: The second electrolyte membrane is subjected to a sixth pressure treatment; The positive electrode sheet after the fifth pressure treatment is placed opposite to the second electrolyte membrane after the sixth pressure treatment, and a seventh pressure treatment is performed to obtain a pre-formed composite positive electrode.

7. The method according to claim 6, characterized in that, The fifth pressure treatment involves a pressure of 20 MPa-40 MPa and a temperature range of 20℃-100℃; and / or, The sixth pressure treatment involves a pressure of 5 MPa-10 MPa and a temperature range of 20℃-100℃; and / or, The seventh pressure treatment involves a pressure of 10MPa-20MPa and a temperature range of 20℃-100℃; and / or, The pressure for the eighth pressure treatment is 40MPa-80MPa, and the temperature range is 20℃-100℃.

8. The method according to claim 7, characterized in that, The porosity of the positive electrode sheet after the fifth pressure treatment is 20%-30%; and / or, The porosity of the second electrolyte membrane after the sixth pressure treatment is 40%-50%; and / or, After the seventh pressure treatment, the porosity of the second electrolyte membrane in the preformed composite positive electrode is 20%-30%; and / or, After the n2th eighth pressure treatment, the porosity of the composite positive electrode is less than or equal to 10%.

9. The method according to claim 5, characterized in that, 4≤n2≤8。 10. The method according to claim 1, characterized in that, The pressure of the third pressing process is 20MPa-40MPa, and the temperature range is 20℃-100℃.

11. The method according to claim 6, characterized in that, The first electrolyte membrane comprises a sulfide electrolyte, which includes a sulfide-germanium sulfide electrolyte, Li3PS4, and Li6PS5Cl. 1-x Br x At least one of them; and / or, The second electrolyte membrane comprises a halide electrolyte, wherein the halide electrolyte comprises at least one of Li2InCl6 and Li2ZrCl6.

12. An all-solid-state battery, characterized in that, It is prepared by the method described in any one of claims 1-11.

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