Silicon-based negative electrode solid-state battery and preparation method thereof

Abstract

The invention relates to the technical field of batteries, and provides a silicon-based negative electrode solid-state battery and a preparation method thereof, and the preparation method comprises the following steps: assembling a positive electrode, a solid electrolyte layer and a silicon-based negative electrode to obtain a prefabricated solid-state battery; charging and discharging circulation is conducted on the prefabricated solid-state battery in the state that the first pressure is applied, after the prefabricated solid-state battery is charged for the first time, pressing treatment is conducted on the prefabricated solid-state battery in the state that the second pressure is applied, and the second pressure is larger than the first pressure; and continuously carrying out charge-discharge circulation on the pressed prefabricated solid-state battery in a state of applying the first pressure to prepare the silicon-based negative electrode solid-state battery. The prefabricated solid-state battery charged for the first time is pressed, so that the interface contact condition of the silicon-based negative electrode is effectively improved, the structural stability of the silicon-based negative electrode is improved, and the electrochemical performance of the silicon-based negative electrode solid-state battery is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a silicon-based negative electrode solid-state battery and a preparation method thereof. Background Art

[0002] Silicon-based anodes have become an important research object for sulfide all-solid-state batteries due to their advantages such as high specific capacity, low cost, low risk of lithium precipitation, and good interface compatibility. However, during the process of lithium insertion and extraction, the volume of silicon materials changes greatly, which reduces the stability of the electrode structure, hinders the transmission of ions and electrons, leads to increased polarization and capacity loss, and seriously affects the rate and cycle performance of solid-state silicon-based anodes. Therefore, how to maintain good contact between electrode components during lithium insertion and extraction is very important for improving the electrochemical performance of solid-state silicon-based anodes. Summary of the invention

[0003] Based on this, an embodiment of the present application provides a silicon-based negative electrode solid-state battery with good interface contact and a preparation method thereof.

[0004] In a first aspect, the present application provides a method for preparing a silicon-based negative electrode solid-state battery, the preparation method comprising:

[0005] Assembling a positive electrode, a solid electrolyte layer and a silicon-based negative electrode to obtain a prefabricated solid-state battery;

[0006] Performing a charge-discharge cycle on the prefabricated solid-state battery under a first pressure, and after the prefabricated solid-state battery is charged for the first time, performing a pressing process on the prefabricated solid-state battery under a second pressure, wherein the second pressure is greater than the first pressure;

[0007] The prefabricated solid-state battery after the pressing process is continuously subjected to charge and discharge cycles while the first pressure is applied, so as to prepare the silicon-based negative electrode solid-state battery.

[0008] In some embodiments, the first charging rate of the prefabricated solid-state battery is 0.05C~0.2C.

[0009] In some embodiments, the state of charge of the prefabricated solid-state battery after the first charge is 30% to 100%.

[0010] In some embodiments, the first pressure is 1 MPa~200 MPa.

[0011] In some embodiments, the second pressure is 200 MPa to 1500 MPa.

[0012] In some embodiments, the pressing treatment time is 1 min to 10 min.

[0013] In some embodiments, the method of assembling the prefabricated solid-state battery comprises:

[0014] pressing a first solid electrolyte material to form a solid electrolyte layer;

[0015] A composite positive electrode material is pressed on one side of the solid electrolyte layer to form a positive electrode, and a composite negative electrode material is pressed on the other side of the solid electrolyte layer to form a silicon-based negative electrode, and the prefabricated solid-state battery is assembled.

[0016] In some embodiments, the composite negative electrode material includes a silicon negative electrode material, a second solid electrolyte material, and a first conductive agent.

[0017] Optionally, the mass ratio of the silicon negative electrode material, the second solid electrolyte material and the conductive agent is 50~100:0~45:0~10.

[0018] In some embodiments, the silicon anode material includes silicon.

[0019] In some embodiments, the volume average particle size Dv50 of the silicon negative electrode material is 0.1 μm to 10 μm.

[0020] In some embodiments, the composite positive electrode material includes a positive electrode active material, a third solid electrolyte material, and a second conductive agent.

[0021] Optionally, the mass ratio of the positive electrode active material, the third solid electrolyte material and the second conductive agent is 60-85:15-35:1-10.

[0022] In a second aspect, the present application provides a silicon-based negative electrode solid-state battery, which is prepared by the preparation method of the silicon-based negative electrode solid-state battery as described in the first aspect.

[0023] Compared with the traditional technology, this application has at least the following beneficial effects:

[0024] The present application performs a secondary pressing process on the prefabricated solid-state battery after the first charge. Since the silicon-based negative electrode is embedded with lithium to form a lithium-silicon alloy during the charging process, its modulus is significantly lower than that of the original silicon material, and it is easy to deform during the pressing process, thereby effectively improving the interface contact of the silicon-based negative electrode. In addition, the silicon material will change from a crystalline state to an amorphous state after the first lithium insertion, and its stress-strain relationship will change from anisotropy to isotropy. Therefore, the structure of the silicon-based negative electrode after the secondary pressing will be more stable, thereby effectively improving the electrochemical performance of the silicon-based negative electrode solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison chart of the discharge specific capacity of the silicon-based negative electrode solid-state battery in Example 1 of the present application and Comparative Example 1. DETAILED DESCRIPTION

[0026] Below in conjunction with the embodiments and examples, the present application is further described in detail. These embodiments and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms, and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent form obtained also falls within the protection scope of the present application. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0028] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0029] In this application, the terms "first", "second", etc. in "the first aspect", "the second aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0030] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0031] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for a broad range of quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0032] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0033] In traditional technology, in order to improve the interfacial contact of solid-state electrodes, the main methods used are adding binders, applying higher molding pressures during the electrode preparation stage, and applying higher operating pressures during the battery operation stage. For example, a higher molding pressure (500MPa~1500MPa) is applied during the electrode preparation stage to reduce the porosity of the solid-state electrode as much as possible and improve the contact between the electrode components. However, since the shape of silicon particles is often irregular and not easy to deform, even if the molding pressure is as high as hundreds or even thousands of MPa, the compaction density of the solid-state silicon-based negative electrode is difficult to further increase, resulting in a high degree of tortuosity in the transmission of ions and electrons. In the subsequent lithium insertion and extraction process, the electrode structure will still change due to the expansion and contraction of silicon, further affecting the ion and electron transmission pathways. Therefore, the above methods are difficult to improve the electrochemical properties of silicon-based negative electrode solid-state batteries, especially the rate performance.

[0034] The first aspect of the present application provides a method for preparing a silicon-based negative electrode solid-state battery, the preparation method comprising:

[0035] Assembling a positive electrode, a solid electrolyte layer and a silicon-based negative electrode to obtain a prefabricated solid-state battery;

[0036] Performing a charge-discharge cycle on the prefabricated solid-state battery under a first pressure, and after the prefabricated solid-state battery is charged for the first time, performing a pressing process on the prefabricated solid-state battery under a second pressure, wherein the second pressure is greater than the first pressure;

[0037] The prefabricated solid-state battery after the pressing process is continuously subjected to charge and discharge cycles while the first pressure is applied, so as to prepare the silicon-based negative electrode solid-state battery.

[0038] The present application performs a secondary pressing process on the prefabricated solid-state battery after the first charge. Since the silicon-based negative electrode is embedded with lithium to form a lithium-silicon alloy during the charging process, its modulus is significantly lower than that of the original silicon material, and it is easy to deform during the pressing process, thereby effectively improving the interface contact of the silicon-based negative electrode. In addition, the silicon material will change from a crystalline state to an amorphous state after the first lithium insertion, and its stress-strain relationship will change from anisotropy to isotropy. Therefore, the structure of the silicon-based negative electrode after the secondary pressing will be more stable, thereby effectively improving the electrochemical performance of the silicon-based negative electrode solid-state battery.

[0039] In some embodiments, the ambient temperature during the charge and discharge cycle is 25°C to 60°C.

[0040] In some embodiments, the prefabricated solid-state battery is charged for the first time at a rate of 0.05C to 0.2C, for example, 0.05C, 0.06C, 0.08C, 0.10C, 0.12C, 0.14C, 0.16C, 0.18C or 0.20C. The first charging rate selected in the present application as above can promote relatively uniform lithiation of the silicon-based negative electrode and ensure the stability of the electrode structure during the pressing process. If the charging rate is relatively high, it may cause uneven lithiation of the silicon-based negative electrode in the thickness direction, thereby causing an unstable electrode structure and affecting the effect of the pressing process.

[0041] In some embodiments, the state of charge of the prefabricated solid-state battery after the first charge is 30% to 100%, for example, it can be 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%. The present application selects the state of charge of the prefabricated solid-state battery after charging as above, which can promote the formation of a lithium-silicon alloy with a lower modulus inside the silicon-based negative electrode, thereby ensuring the effect of the pressing treatment. If the state of charge is relatively low, it may result in a small amount of lithium-silicon alloy formed in the silicon-based negative electrode, and the silicon-based negative electrode still contains a high content of silicon material. The silicon material is not sufficiently deformed during the pressing process, and the problem of interface contact cannot be effectively improved.

[0042] It is understandable that in this application, if the state of charge of the prefabricated solid-state battery after the first charge is less than 100%, the prefabricated solid-state battery after the pressing treatment continues to be charged until the state of charge is 100%, and then the charge and discharge cycle is performed. The subsequent charge and discharge cycles can refer to the formation operation of the silicon-based negative electrode solid-state battery to select the charge and discharge rate and the number of cycles; if the state of charge of the prefabricated solid-state battery after charging is 100%, the prefabricated solid-state battery after the pressing treatment is discharged, and then the charge and discharge cycle is performed. The subsequent charge and discharge cycles can refer to the formation operation of the silicon-based negative electrode solid-state battery to select the charge and discharge rate and the number of cycles. It should be noted that in the process of pressing treatment in this application, it is not necessary to charge the prefabricated solid-state battery.

[0043] It is understandable that in one charge and discharge cycle, the charge rate and discharge rate should be the same. That is, the charge rate of the prefabricated solid-state battery in the first charge process in this application is 0.05C~0.2C. Correspondingly, the discharge rate in the first discharge process should also be 0.05C~0.2C, which is the same as the charge rate of the first charge.

[0044] In some embodiments, the first pressure is 1 MPa to 200 MPa, for example, 1 MPa, 10 MPa, 20 MPa, 40 MPa, 60 MPa, 80 MPa, 100 MPa, 120 MPa, 140 MPa, 160 MPa, 180 MPa or 200 MPa.

[0045] In some embodiments, the second pressure is 200MPa to 1500MPa, for example, 200MPa, 300MPa, 400MPa, 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, 1000MPa, 1100MPa, 1200MPa, 1300MPa, 1400MPa or 1500MPa. The second pressure selected in the pressing process as above in the present application ensures that the lithium-silicon alloy can be fully deformed during the pressing process to avoid insufficient pressure affecting the pressing effect, and on the other hand, avoids excessive pressure causing the positive electrode particles to break.

[0046] In some embodiments, the pressing treatment time is 1 min to 10 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0047] It is understandable that the assembly method of the prefabricated solid-state battery can be adjusted according to the type of silicon-based anode solid-state battery. For example, the silicon-based anode solid-state battery can also be a soft-pack solid-state battery, which can be assembled by pressing together the positive electrode, negative electrode and solid electrolyte membrane prepared in advance by wet or dry methods. This application does not make specific requirements and special limitations on the assembly method of the prefabricated solid-state battery.

[0048] In some embodiments, the method for assembling the prefabricated solid-state battery comprises:

[0049] pressing a first solid electrolyte material to form a solid electrolyte layer;

[0050] A composite positive electrode material is pressed on one side of the solid electrolyte layer to form a positive electrode, and a composite negative electrode material is pressed on the other side of the solid electrolyte layer to form a silicon-based negative electrode, and the prefabricated solid-state battery is assembled.

[0051] In some embodiments, the composite negative electrode material includes a silicon negative electrode material, a second solid electrolyte material, and a first conductive agent.

[0052] Optionally, the mass ratio of the silicon negative electrode material, the second solid electrolyte material and the conductive agent is 50~100:0~45:0~10.

[0053] In some embodiments, the silicon anode material includes silicon.

[0054] In some embodiments, the volume average particle size Dv50 of the silicon negative electrode material is 0.1μm~10μm, for example, it can be 0.1μm, 0.2μm, 0.5μm, 0.8μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0055] In some embodiments, the composite positive electrode material includes a positive electrode active material, a third solid electrolyte material, and a second conductive agent.

[0056] Optionally, the mass ratio of the positive electrode active material, the third solid electrolyte material and the second conductive agent is 60-85:10-35:1-10.

[0057] In some embodiments, the positive electrode material can be selected according to the silicon-based negative electrode solid-state battery, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2.

[0058] It is understandable that the materials of the first solid electrolyte, the second solid electrolyte and the third solid electrolyte in the present application can be selected according to the requirements of the silicon-based negative electrode solid-state battery, and the materials of the first solid electrolyte, the second solid electrolyte and the third solid electrolyte can be the same or different. For example, the first solid electrolyte, the second solid electrolyte and the third solid electrolyte are all Li6PS5Cl.

[0059] It is understood that the first conductive agent and the second conductive agent in the present application can be selected according to the requirements of the silicon-based negative electrode solid-state battery, and the first conductive agent and the second conductive agent can be the same or different. For example, the first conductive agent and the second conductive agent are both conductive carbon. Optionally, the conductive carbon can be vapor grown carbon fiber (Vapor Grown Carbon Fiber, VGCF).

[0060] Exemplarily, a method for preparing the above-mentioned solid-state battery is provided, comprising the following steps:

[0061] pressing a first solid electrolyte material to form a solid electrolyte layer;

[0062] A composite positive electrode material is used to press a positive electrode on one side of the solid electrolyte layer, and a composite negative electrode material is used to press a silicon-based negative electrode on the other side of the solid electrolyte layer, and the prefabricated solid-state battery is assembled;

[0063] The prefabricated solid-state battery is charged for the first time under a first pressure, the first charging rate is 0.05C~0.2C, and the prefabricated solid-state battery with a charge state of 30%~100% after the first charging is pressed under a second pressure, the first pressure is 1MPa~200MPa, and the second pressure is 200MPa~1500MPa;

[0064] The prefabricated solid-state battery after the pressing process is continuously subjected to charge and discharge cycles while the first pressure is applied, so as to prepare a silicon-based negative electrode solid-state battery.

[0065] A second aspect of the present application provides a silicon-based negative electrode solid-state battery, which is prepared by the preparation method of the silicon-based negative electrode solid-state battery as described in the first aspect.

[0066] In some embodiments, a silicon-based negative electrode solid-state battery includes a positive electrode and a silicon-based negative electrode alternately stacked, and also includes a solid electrolyte layer located between the positive electrode and the silicon-based negative electrode.

[0067] In some embodiments, the thickness of the positive electrode is 20 μm to 200 μm.

[0068] In some embodiments, the thickness of the silicon-based negative electrode is 5 μm to 50 μm.

[0069] In some embodiments, the solid electrolyte layer has a thickness of 20 μm to 600 μm.

[0070] Furthermore, the present application also provides an electrical device, comprising the above-mentioned silicon-based negative electrode solid-state battery of the present application.

[0071] The above-mentioned electrical devices may include any equipment or devices that use secondary batteries as driving sources, such as mobile phones, laptop computers, electric vehicles, ships, satellites, energy storage devices, smart home appliances, etc., but are not limited thereto.

[0072] The embodiments of the present application will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0073] Example 1

[0074] Silicon with a volume average particle size of 3 μm, sulfide electrolyte Li6PS5Cl and conductive carbon VGCF were weighed in a mass ratio of 60:35:5 and added to a mortar, and manually ground and mixed for 30 minutes to obtain a composite negative electrode material; active material NCM111, sulfide electrolyte Li6PS5Cl and conductive carbon VGCF were weighed in a mass ratio of 70:25:5 and added to a mortar, and manually ground and mixed for 20 minutes to obtain a composite positive electrode material.

[0075] A Si|Li6PS5Cl|NCM all-solid-state battery was assembled using a mold with a diameter of 10 mm. First, 85 mg of sulfide electrolyte Li6PS5Cl powder was weighed and added to the mold to be flattened, and then pressed at a pressure of 300 MPa for 2 minutes to obtain a solid electrolyte layer; then 44.0 mg of the above-mentioned composite positive electrode material was weighed and evenly flattened on one side of the solid electrolyte layer, and pressed at a pressure of 300 MPa for 2 minutes to form a positive electrode; then 2.7 mg of the above-mentioned composite negative electrode material was weighed and evenly flattened on the other side of the solid electrolyte layer, and pressed at a pressure of 900 MPa for 2 minutes to form a silicon-based negative electrode; finally, a stainless steel clamp was used to apply a first pressure of 100 MPa to the mold battery to assemble a prefabricated solid-state battery for the next step of electrochemical testing. The entire assembly process was carried out in a glove box filled with argon, and the environmental requirements were that the water content was <0.01 ppm and the oxygen content was <0.01 ppm.

[0076] The assembled prefabricated solid-state battery was transferred to a constant temperature box with an ambient temperature of 45°C and allowed to stand for 12 hours. The prefabricated solid-state battery was then subjected to rate charge and discharge tests using the Neware battery testing system. The first three cycles were charged and discharged at 0.1C. After the first charge to 4.2V at 0.1C (i.e., the state of charge was 100%), the prefabricated solid-state battery was removed from the stainless steel fixture and pressed again at the second pressure for 2 minutes. The second pressure was 900MPa. The stainless steel fixture was then used again to apply the first pressure to the mold battery. The first pressure was 100MPa. The battery was returned to the constant temperature box and allowed to stand for 30 minutes before being discharged at 0.1C to 2.4V. The battery was then cycled for 2 more cycles at 0.1C to complete the formation process. The battery was then cycled for 3 cycles at 0.2C, 0.5C, 1C, and 2C, respectively.

[0077] Example 2

[0078] A silicon-based negative electrode solid-state battery was prepared according to the method of Example 1, except that the first charging rate was 0.3C.

[0079] Example 3

[0080] A silicon-based negative electrode solid-state battery was prepared according to the method of Example 1, except that the second pressure in the pressing process was 100 MPa.

[0081] Example 4

[0082] A silicon-based negative electrode solid-state battery was prepared according to the method of Example 1, except that the second pressure in the pressing process was 1600 MPa.

[0083] Example 5

[0084] A silicon-based negative electrode solid-state battery is prepared according to the method of Example 1, except that the state of charge of the prefabricated solid-state battery after charging is 20%.

[0085] Comparative Example 1

[0086] A silicon-based negative electrode solid-state battery is prepared according to the method of Example 1, except that no pressing treatment is performed during the charge and discharge cycle.

[0087] The discharge specific capacity and initial efficiency test results of the silicon-based negative electrode solid-state battery in the above embodiment and comparative example 1 during the charge and discharge cycle at 0.1C, 0.2C, 0.5C, 1C and 2C are shown in Table 1, wherein the discharge specific capacity comparison diagram of embodiment 1 and comparative example 1 is shown in Figure 1 shown.

[0088] Table 1

[0089]

[0090] From the above table we can see that:

[0091] (1) Compared with Example 2, it can be seen that the present application controls the charging rate of the prefabricated solid-state battery before the pressing process, which can promote relatively uniform lithiation of the silicon-based negative electrode and ensure the stability of the electrode structure during the pressing process. If the charging rate is relatively high, it may cause the silicon-based negative electrode to have uneven lithiation in the thickness direction, thereby causing the electrode structure to be unstable and affecting the effect of the pressing process.

[0092] (2) Compared with Examples 3-4, it can be seen that the present application controls the second pressure in the pressing process to ensure that the lithium-silicon alloy can be fully deformed during the pressing process to avoid insufficient pressure affecting the pressing effect, and to avoid excessive pressure causing the positive electrode particles to break.

[0093] (3) Compared with Example 5, Example 1 can promote the formation of a lithium-silicon alloy with a low modulus inside the silicon-based negative electrode, thereby ensuring the effect of the pressing treatment. If the state of charge is relatively low, the amount of lithium-silicon alloy formed in the silicon-based negative electrode may be small, and the silicon-based negative electrode still contains a high content of silicon material. The silicon material is not sufficiently deformed during the pressing process, and the problem of interface contact cannot be effectively improved.

[0094] (4) Compared with Comparative Example 1, it can be seen that the present application performs a secondary pressing process on the prefabricated solid-state battery after the first charge. Since the silicon-based negative electrode is embedded with lithium to form a lithium-silicon alloy during the charging process, its modulus is significantly reduced compared with the original silicon material, and it is easy to deform during the pressing process, thereby effectively improving the interface contact of the silicon-based negative electrode. In addition, the silicon material will change from a crystalline state to an amorphous state after the first lithium insertion, and its stress-strain relationship will change from anisotropy to isotropy. Therefore, the silicon-based negative electrode structure after the secondary pressing will be more stable, thereby effectively improving the electrochemical performance of the silicon-based negative electrode solid-state battery.

[0095] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0096] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the application. It should be noted that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a silicon-based negative electrode solid-state battery, characterized in that: The preparation method comprises: Assembling a positive electrode, a solid electrolyte layer and a silicon-based negative electrode to obtain a prefabricated solid-state battery; Performing a charge-discharge cycle on the prefabricated solid-state battery under a first pressure, and after the prefabricated solid-state battery is charged for the first time, performing a pressing process on the prefabricated solid-state battery under a second pressure, wherein the second pressure is greater than the first pressure; The prefabricated solid-state battery after the pressing process is continuously subjected to charge and discharge cycles while the first pressure is applied, so as to prepare the silicon-based negative electrode solid-state battery.

2. The method for preparing a silicon-based negative electrode solid-state battery according to claim 1, characterized in that: The prefabricated solid-state battery is charged at a rate of 0.05C to 0.2C for the first time.

3. The method for preparing a silicon-based negative electrode solid-state battery according to claim 1, characterized in that: The state of charge of the prefabricated solid-state battery after the first charge is 30% to 100%.

4. The method for preparing a silicon-based negative electrode solid-state battery according to claim 1, characterized in that: The method for preparing the solid-state battery satisfies at least one of the following conditions: (1) The first pressure is 1 MPa~200 MPa; (2) The second pressure is 200 MPa~1500 MPa.

5. The method for preparing a silicon-based negative electrode solid-state battery according to claim 1, characterized in that: The pressing treatment time is 1 min to 10 min.

6. The method for preparing a silicon-based negative electrode solid-state battery according to any one of claims 1 to 5, characterized in that: The assembly method of the prefabricated solid-state battery comprises: pressing a first solid electrolyte material to form a solid electrolyte layer; A composite positive electrode material is pressed on one side of the solid electrolyte layer to form a positive electrode, and a composite negative electrode material is pressed on the other side of the solid electrolyte layer to form a silicon-based negative electrode, and the prefabricated solid-state battery is assembled.

7. The method for preparing a silicon-based negative electrode solid-state battery according to claim 6, characterized in that: The composite negative electrode material comprises a silicon negative electrode material, a second solid electrolyte material and a first conductive agent; Optionally, the mass ratio of the silicon negative electrode material, the second solid electrolyte material and the conductive agent is 50~100:0~45:0~10.

8. The method for preparing a silicon-based negative electrode solid-state battery according to claim 7, characterized in that: The silicon negative electrode material meets at least one of the following conditions: (1) The silicon negative electrode material comprises silicon; (2) The volume average particle size Dv50 of the silicon negative electrode material is 0.1 μm to 10 μm.

9. The method for preparing a silicon-based negative electrode solid-state battery according to claim 6, characterized in that: The composite positive electrode material comprises a positive electrode active material, a third solid electrolyte material and a second conductive agent; Optionally, the mass ratio of the positive electrode active material, the third solid electrolyte material and the second conductive agent is 60-85:15-35:1-10.

10. A silicon-based negative electrode solid-state battery, characterized in that: The silicon-based negative electrode solid-state battery is prepared by the preparation method of the silicon-based negative electrode solid-state battery according to any one of claims 1 to 9.

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