A Method for Controlling the Solid Electrolyte Interface of All-Solid-State Secondary Batteries

Abstract

The present invention discloses a method for regulating the solid electrolyte interface of an all-solid-state secondary battery. After assembling the positive electrode sheet, negative electrode sheet, and solid electrolyte into an electric core, without pressing, it is first charged at a current of 0.005 - 0.015C until the content of C-C and / or C-O groups increases by 2% - 10%, completing the first charging stage. Then, a pressure of 0.5 - 2 MPa is applied to the electric core for pressing, and the electric core is heated during the pressing process. The heating temperature is higher than the charging temperature in the first charging stage. Press until the thickness of the electric core decreases by 10% - 30%, and then continue charging for formation. In the above solution, by limiting the charging rate and the content of specific groups in the first charging stage, the selection of the solid electrolyte interface components formed in the first charging stage is realized, and by pressing the electric core under heating conditions, the uniformity of the solid electrolyte interface is improved, thereby leading to an increase in the consistency of the current density.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical power sources, and specifically relates to a method for regulating the solid electrolyte interface of a all-solid-state secondary battery. Background Art

[0002] Lithium-ion batteries have the characteristics of high energy density, high power, long life, etc., and are widely used in energy storage, 3C, automotive and even military fields; with the development of lithium battery related technologies, people have put forward higher requirements for their energy density, cycle performance and safety.

[0003] At present, lithium-ion batteries mainly include three categories: liquid, quasi-solid-state and all-solid-state. Among them, there are liquid electrolytes in liquid lithium-ion batteries and quasi-solid-state lithium-ion batteries, which are prone to thermal runaway under high temperature, humidity, overcharge, over-discharge or violent impact, etc., and then combustion and explosion accidents occur; in contrast, all-solid-state lithium-ion batteries have higher safety; however, both the electrolyte and the electrode in all-solid-state lithium-ion batteries are solid, and the poor contact of the solid-solid interface leads to low ionic conductivity, which limits the development and application of all-solid-state lithium-ion batteries.

[0004] The Chinese invention patent with the application number CN202010245930.9 discloses a solution of setting a buffer layer between the electrode sheet and the solid electrolyte to eliminate the interface resistance and improve the ionic conductivity through the buffer layer.

[0005] The Chinese invention patent with the application number CN201810092084.4 discloses a solution of coating an electrolyte layer on the surfaces of the positive electrode and the negative electrode, and combining the positive electrode and the negative electrode sheets after heat treatment to obtain an all-solid-state lithium-ion battery.

[0006] The Chinese invention patent with the application number CN202010364972.4 discloses a formation method of constant current charging, pulse charging and constant current discharging in sequence under the condition that a fixture clamps the all-solid-state battery and applies pressure.

[0007] The above-mentioned existing patents improve the interface performance of all-solid-state batteries in different ways, but in the formation stage, the current density is affected by the distance between the solid-solid interfaces, resulting in poor uniformity of the solid electrolyte interface, which directly affects the performance of all-solid-state batteries.

[0008] In view of this, the present invention is specifically proposed. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to solve one of the above-mentioned problems in the prior art, and provide a method for regulating the solid electrolyte interface of an all-solid-state secondary battery. After the assembled battery core is charged, it is pressed to improve the consistency of the solid electrolyte interface.

[0010] To solve the above technical problems, the present invention provides a method for regulating the solid electrolyte interface of a all-solid-state secondary battery, where the assembled battery cell is pressed after charging.

[0011] In the above solution, pressing after charging makes the components of the solid electrolyte interface formed during the charging process more uniform under the influence of pressure on the one hand; on the other hand, the contact at the solid-solid interface inside the battery cell is more sufficient under the action of pressure, improving the stability of the solid electrolyte interface during subsequent charging, while enhancing the ion transport efficiency and effectively avoiding the formation of lithium dendrites, thereby improving the safety and service life of the battery.

[0012] Further, the capacity of the battery cell during pressing does not exceed 50% SOC.

[0013] Further, before pressing the battery cell, it at least includes a first charging stage;

[0014] After charging to a content increase of C-C and / or C-O groups by more than 2% in the first charging stage, the battery cell is pressed.

[0015] Since the formation of the solid electrolyte interface cannot be directly observed during the charging process, by observing the changes in the C-C and / or C-O groups through detection means such as XPS, the formation state of the solid electrolyte interface can be judged more accurately, ensuring that the formation state of the solid electrolyte interface meets the pressing requirements, and thus improving the pressing effect after charging.

[0016] Further, it is characterized in that after charging to a content increase of C-C and / or C-O groups by 2% - 10%, the battery cell is pressed.

[0017] In the above solution, by controlling the content of C-C and / or C-O groups, the pressing is controlled in the early stage of the formation of the solid electrolyte interface. On the one hand, it can significantly improve the stability, uniformity and consistency of the solid electrolyte interface, and on the other hand, it also avoids defects or damage to the structure of the solid electrolyte interface caused by pressing in the later stage of the formation of the solid electrolyte interface.

[0018] Further, before pressing, the battery cell is charged at a charging rate of 0.005 - 0.015C.

[0019] The above solution ensures the effective activation of the solid electrolyte interface components through a smaller charging rate, and on the other hand, enables the initial formation of the solid electrolyte interface to be more uniform, ensuring a higher stability and a solid electrolyte interface conducive to lithium ion migration after pressing.

[0020] Further, the pressure range for pressing the battery cell is 0.5 - 2 MPa.

[0021] In the above solution, the selection of the pressure range is a relatively preferred range confirmed by technicians based on a large amount of research. Pressing at a pressure of 0.5 - 2 MPa can provide sufficient pressure to the battery cell. On the one hand, it can fully press the solid electrolyte interface, and at the same time compress the overall thickness of the battery cell, enabling the solid-solid interface between the solid electrolyte and the electrode to have more sufficient contact; on the other hand, by applying pressure to the solid electrolyte, the internal structure of the battery cell becomes more compact, and at the same time, local defects of the solid electrolyte are repaired; if the pressure is too small, the pressing effect on the solid electrolyte interface will decline, and it may be impossible to form a uniform solid electrolyte interface; if the pressure is too large, the battery cell may be damaged.

[0022] Further, the battery cell is pressed under the condition of a preset temperature.

[0023] Preferably, the preset temperature is higher than the charging temperature during the charging process before pressing.

[0024] In the above solution, while pressing, the battery cell is heated at a preset temperature, and the solid electrolyte interface is softened to a certain extent and can be more easily pressed evenly; since the charging stage before pressing may be carried out under heating conditions, and the battery cell inevitably generates self-heat during the charging process, in order to further heat the battery cell during the pressing process, the preset temperature is actually set to be higher than the charging temperature before pressing.

[0025] It should be noted here that when the charging stage before pressing is carried out under heating conditions, the charging temperature is the heating temperature during the charging stage before pressing; when the charging stage before pressing is carried out at room temperature, the charging temperature is the actual temperature of the battery cell at the end of the charging stage before pressing.

[0026] Further, the preset temperature is 5 - 20 °C higher than the temperature of the first charging stage.

[0027] Or, parallel to the above solution, the preset temperature satisfies:

[0028] Y + 5 °C ≤ X ≤ Y + 20 °C

[0029] Wherein, X is the preset temperature; Y is the lowest value of the melting limit in the solid electrolyte interface formed during the first charging stage.

[0030] In the above solution, the preset temperature is slightly higher than the lowest value of the melting limit in the solid electrolyte interface. During the pressing process, some components in the solid electrolyte interface undergo phase changes due to heat, and other components can also be softened to a certain extent at the preset temperature, so that a more uniform solid electrolyte interface can be obtained, further improving the stability of the solid electrolyte interface.

[0031] Furthermore, compared with before the pressing starts, the thickness of the battery cell decreases by 10-30% after pressing.

[0032] As can be seen from the above change rate of the battery cell thickness, during the charging stage before pressing, the battery cell as a whole maintains a relatively loose state, and the microscopic distance between the solid electrolyte and the electrode at the solid-solid interface is relatively large, which provides more sufficient space for the formation of the solid electrolyte interface; during the pressing process, the thickness of the battery cell decreases, and the microscopic distance between the solid-solid interfaces decreases. On the one hand, the contact effect at the interface is improved, and on the other hand, the already formed solid electrolyte interface spreads under the action of pressure, improving the distribution uniformity on the solid-solid interface.

[0033] Furthermore, the assembled battery cell is alternately charged and pressed.

[0034] In the above solution, charging and pressing are alternately cycled. As charging progresses, the battery cell is repeatedly pressed, and a solid electrolyte interface with higher uniformity and consistency can be obtained.

[0035] Furthermore, arranged according to the charging time sequence, the subsequent pressing pressure is greater than the previous pressing pressure.

[0036] Preferably, arranged according to the charging time sequence, the subsequent pressing temperature is greater than the previous pressing temperature.

[0037] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0038] 1. After the battery cell is assembled, it is not pressed first but charged. Charging is carried out in a state where the microscopic gap at the solid-solid interface in the battery cell is relatively large, providing a larger formation space for the solid electrolyte interface. During the subsequent pressing process, affected by the pressure, the solid electrolyte interface can spread to a certain extent at the interface, improving the uniformity and consistency of the solid electrolyte interface.

[0039] 2. Charge at a current of 0.005-0.015C until the content of C-C and / or C-O groups increases by 2%-10%. On the one hand, a lower charging rate is used to ensure that the generated solid electrolyte interface itself has higher uniformity; on the other hand, the change in the component content of the solid electrolyte interface during the charging process can be regulated. Through regulation, the solid electrolyte interface can better meet the pressing requirements, and then a solid electrolyte interface with excellent stability can be obtained after pressing.

[0040] 3. Press the battery cell under heating conditions, which improves the fluidity of the solid electrolyte interface to a certain extent, further enhances the stability and uniformity of the solid electrolyte interface after pressing; at the same time, it can repair the defects inside the solid electrolyte; the temperature of the hot pressing can be adjusted according to the charging temperature in the charging stage before pressing, or can be adjusted according to the melting limit of the formed solid electrolyte interface, but generally it is higher than the charging temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the SEM image of the surface of the electrode sheet after the battery cell prepared in Example 1 of the present invention is disassembled after 100 charge-discharge cycles;

[0042] Figure 2 is the SEM image of the surface of the electrode sheet after the battery cell prepared in Comparative Example 1 of the present invention is disassembled after 100 charge-discharge cycles. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0044] In the description of the present invention, without special explanation, the term "A and / or B" is understood in the normal sense, and its meaning includes: only A, only B, and the situation where A and B exist simultaneously.

[0045] Without special explanation, the "hot pressing" mentioned in the present invention means heating while pressing the battery cell.

[0046] It needs to be explained in advance that in the formation steps mentioned in the following embodiments, without special explanation, the default formation capacity is 80% SOC.

[0047] The present invention provides a method for regulating the solid electrolyte interface of a all-solid-state secondary battery. After the battery cell is assembled, it is first charged and then pressed. By pressing, on the one hand, the microscopic gap at the solid-solid interface is reduced; on the other hand, the solid electrolyte interface becomes more uniform, improving the uniformity of the solid electrolyte interface; and, by pressing the battery cell, the internal structure of the battery cell becomes more compact, which can reduce or even repair the defects inside the solid electrolyte to a certain extent, and reduce the capacity loss of the battery during the first charge and discharge process.

[0048] The charging process before pressing includes at least a first charging stage, and may also include two or more charging stages. The charging rates, charging capacities, and the increasing ratios of C-C and / or C-O groups in each charging stage may be the same or different from each other. By designing the solid electrolyte interface more precisely through multiple charging stages, the pressed solid electrolyte interface has higher stability.

[0049] When the first charging stage ends and whether to perform pressing are judged according to the change in the content of C-C and / or C-O groups in the solid electrolyte interface. During the pressing process, better pressing effects can be obtained by utilizing the property that organic components are more easily softened and deformed. The change in C-C and / or C-O groups can intuitively reflect the generation state of organic components, and thus can accurately judge whether the solid electrolyte interface reaches the state where it can be pressed.

[0050] In addition, based on a large amount of research, technicians found that the generation of LiCO3, Li2O, and LiF in the inorganic components is basically not affected by the type of active material and electrolyte. Therefore, for the generation state of the negative electrode solid electrolyte interface, it can also be judged by the change in the generation amount of LiF. When the C-C and / or C-O bonds increase by 2%-10%, the corresponding generation amount of LiF can also be used as a standard to judge whether the solid electrolyte interface can be pressed.

[0051] However, neither the generation state nor the growth degree of C-C, C-O, or LiF can be directly observed during the charging process. Therefore, through the selective relationship between different charging parameters and the generation of components in the solid electrolyte interface, by restricting and observing macroscopic parameters such as current and time in the first charging stage, it is ensured that the cell is pressed after the generation amount of LiF meets the requirements.

[0052] Therefore, the end of the first charging stage can also be judged according to the charging duration, charging capacity, or other relevant parameters at a specific charging current rate. Based on a large amount of experiments and research, technicians in this field found that by setting the current rate of the first charging stage within the range of 0.005-0.015C and setting the target capacity of the first charging stage to 0.5%-2% SOC, the increase in C-C and C-O bonds also correspondingly maintains within the range of 2%-10% under these conditions, and at this time the solid electrolyte interface can fully meet the requirements of subsequent pressing.

[0053] After the end of the first charging stage, the battery cell is pressed to physically squeeze the solid electrolyte interface, thereby improving the uniformity of the solid electrolyte interface. The pressure for pressing the battery cell is selected within the range of 0.5 - 2 MPa. On the one hand, it can effectively press the solid electrolyte interface; on the other hand, it can avoid damaging the battery cell due to excessive pressure or being unable to effectively press the solid electrolyte interface due to too low pressure. The pressing needs to be maintained for 2 - 10 h.

[0054] In addition, during the pressing process, the battery cell can also be heated. By raising the temperature, the solid electrolyte interface is softened, which is beneficial to further improving the uniformity and stability of the solid electrolyte interface. To achieve the softening of the solid electrolyte interface, the heating temperature is usually higher than the temperature of the first charging stage. For example, the heating temperature can be set 5 - 20 °C higher than the temperature of the first charging stage; or the heating temperature can be set according to the melting limit of the solid electrolyte interface. For example, the heating temperature is set to satisfy the following relationship:

[0055] Y + 5 °C ≤ X ≤ Y + 20 °C

[0056] Wherein, X is the heating temperature; Y is the lowest value of the melting limit in the solid electrolyte interface formed in the first charging stage. The X that satisfies the above relationship is used as the preset temperature during the pressing process, and the battery cell is heated accordingly, so that the components with lower melting points in the solid electrolyte interface undergo phase changes to a certain extent, providing better deformation ability for the solid electrolyte interface, further improving the uniformity and stability of the solid electrolyte interface, and making the internal structure of the solid electrolyte more compact under the action of pressure, realizing the repair of internal defects and improving the ion migration efficiency.

[0057] It should be noted that the charging and pressing of the battery cell can be completed in the same device or in different devices respectively. For example, the charging of the battery cell can be carried out in a conventional formation cabinet, and the pressing of the battery cell can be carried out in an independent pressure device; or a pressure fixture or a pressure fixture with a heating function can be set in the formation cabinet, so that there is no need to repeatedly install and remove the battery cell, which is more convenient.

[0058] In addition, in the following embodiments, a half-cell is assembled from a positive electrode, a negative electrode and a solid electrolyte respectively, and the performance of the half-cell is detected and analyzed, which can better reflect the influence of the change of the solid electrolyte interface on the battery performance. It should be noted that the half-cell assembled from the positive electrode / negative electrode and the solid electrolyte is a soft-pack battery, not the button battery commonly understood by those skilled in the art.

[0059] For the sake of convenience of description, the half-cell assembled from the positive electrode and the solid electrolyte is uniformly written as the positive electrode / Li battery, and the half-cell assembled from the negative electrode and the solid electrolyte is written as the negative electrode / Li battery.

[0060] Next, a specific embodiment is used to further elaborate on the present invention in detail.

[0061] Embodiment 1

[0062] As an embodiment of the present invention, this embodiment provides a method for generating a solid electrolyte interface of a all-solid-state secondary battery, which is specifically as follows.

[0063] Using a positive electrode and a solid electrolyte as raw materials, an electric core is assembled, and then charged at a current rate of 0.005C to 2% SOC at a temperature of 45°C. Then, pressure is applied to the electric core for pressing, controlling the pressure to be 1 MPa and the pressing duration to be 8 h; while pressing, the electric core is heated, and the heating temperature is 65°C. The thickness of the electric core after pressing is 80% of that before pressing. After that, formation is continued at a current rate of 0.3C to obtain a positive electrode / Li battery.

[0064] Embodiment 2

[0065] As another embodiment of the present invention, the main difference between this embodiment and Embodiment 1 is that heating is not performed while pressing the electric core.

[0066] Specifically, using a positive electrode and a solid electrolyte as raw materials, an electric core is assembled, and then charged at a current rate of 0.015C to 0.5% SOC at a temperature of 35°C. Then, pressure is applied to the electric core for pressing, controlling the pressure to be 0.5 MPa and the pressing duration to be 8 h; the thickness of the electric core after pressing is 90% of that before pressing. After that, formation is continued at a current rate of 0.3C to obtain a positive electrode / Li battery.

[0067] The different solid-state batteries obtained by changing the preparation conditions according to the steps described in Embodiment 1 and Embodiment 2 are summarized as follows:

[0068]

[0069]

[0070] Embodiment 10

[0071] As another embodiment of the present invention, the main difference between this embodiment and Embodiment 1 is that the charging process includes two stages.

[0072] Specifically, a battery cell is assembled using a positive electrode and a solid electrolyte as raw materials, and then enters the first charging stage, where it is charged at a current rate of 0.005C to 1% SOC at a temperature of 45°C; then it continues to enter the second charging stage, where it is charged at a current rate of 0.01C to 2% SOC at a temperature of 45°C; after the second charging stage ends, pressure is applied to the battery cell for pressing, controlling the pressure to be 1 MPa, and simultaneously heating the battery cell, with the heating temperature being 65°C, the pressing lasting for 8 h, and the thickness of the battery cell after pressing being 80% of that before pressing; then it continues to complete formation at a current rate of 0.3C to obtain a positive electrode / Li battery.

[0073] Example XI

[0074] As another embodiment of the present invention, the difference between this embodiment and Embodiment 1 is that after the battery cell is assembled, charging and pressing are carried out alternately.

[0075] In this embodiment, a battery cell is assembled using a positive electrode and a solid electrolyte as raw materials, and then enters the first charging stage, where it is charged at a current of 0.005C to 1% SOC at a temperature of 45°C; then the battery cell is subjected to the first pressing at a pressure of 1 MPa until the thickness of the battery cell is 90% of that before pressing, and the battery cell is heated during the first pressing process, with the heating temperature being 65°C; continue to carry out the second charging stage, where it is charged at a current of 0.015C to 3% SOC at a temperature of 45°C; then the battery cell is subjected to the second pressing at a pressure of 2 MPa, controlling the duration of the second pressing to be 6 h, and heating the battery cell while pressing, with the heating temperature being 65°C, and the thickness of the battery cell after the second pressing ends is 90% of that before the second pressing; then it continues to complete formation at a current rate of 0.3C to obtain a positive electrode / Li battery.

[0076] Comparative Example I

[0077] This comparative example prepares a positive electrode / Li battery, and the specific preparation process is as follows.

[0078] A battery cell is assembled using a positive electrode and a solid electrolyte as raw materials respectively, and then under the conditions of 45°C and 50 KPa, it is formed at a current rate of 0.2C to obtain a positive electrode / Li battery.

[0079] Experimental Example I

[0080] This experimental example tests the performance of the all-solid-state batteries prepared in some of the above experimental examples and comparative examples, and the results are shown in the following table:

[0081]

[0082]

[0083] As can be seen from the above data, in Examples 1 to 11, the method of the present invention was adopted, and the initial efficiency of the finally prepared half-cell was significantly improved compared with the comparative example, and the capacity retention rate after 100 cycles at 0.3C was also significantly better than that of Comparative Example 1, indicating that the method of the present invention effectively improved the uniformity of the solid electrolyte interface.

[0084] The difference between Example 2 and Example 1 is that heating is not carried out during the pressing process. The corresponding initial efficiency and capacity retention rate both decreased slightly compared with Example 1, indicating that heating during the pressing process is more conducive to improving the uniformity and consistency of the solid electrolyte interface.

[0085] In Example 4, the charging rate in the first charging stage was increased on the basis of Example 1, and in Example 5, the charging rate in the first charging stage was decreased on the basis of Example 3. The corresponding initial efficiency and capacity retention rate both decreased to a certain extent, indicating that the control of the charging rate in the first charging stage directly affects the uniformity and consistency of the solid electrolyte interface. At too high or too low charging rates, the components of the solid electrolyte interface generated in the first charging stage changed, affecting the pressing effect.

[0086] In Example 6, the target capacity in the first charging stage was increased on the basis of Example 1, and in Example 7, the target capacity in the first charging stage was decreased on the basis of Example 3. The initial efficiency and capacity retention rate of the finally prepared half-cell both decreased to varying degrees; it shows that limiting the target capacity of the charging stage before pressing to 0.5-2% SOC can better cooperate with the pressing step to improve the consistency of the solid electrolyte interface. If the target capacity is too high or too low, the formation state of the solid electrolyte interface cannot meet the pressing requirements; and ultimately affect the uniformity and consistency of the solid electrolyte interface.

[0087] In Examples 8 and 9, the change rate of the thickness of the electrode sheet after pressing was increased and decreased respectively on the basis of Example 1. It can be found that the initial efficiency and capacity retention rate were not measured in Example 8 because the change rate of the thickness was too large, resulting in damage to the battery cell; from the initial efficiency and capacity retention rate of Example 9, it can be seen that the pressure during the pressing process was small, resulting in insufficient pressing, and the uniformity and consistency of the solid electrolyte interface could not be significantly improved during the pressing process, and thus there was no obvious improvement in the initial efficiency and capacity retention rate compared with Comparative Example 1.

[0088] The difference between Example 10 and Example 1 is only that the charging process before pressing was divided into multiple charging stages. From the test results, it can be seen that the final initial efficiency and capacity retention rate are relatively close to those of Example 1, indicating that within the limited charging rate and target capacity, the division of the charging stage will not cause obvious changes in the solid electrolyte interface.

[0089] Experimental Example 2

[0090] In this experimental example, the batteries prepared in each embodiment and comparative example of the present invention were charged and discharged cyclically at a rate of 0.3C, and disassembled at different numbers of cycles to observe the generation of lithium dendrites at the interface. The results are shown in the following table:

[0091]

[0092] As can be seen from the above table, for the half-cell prepared by the method of the present invention, after 100 charge-discharge cycles, only a small amount of filamentous lithium is generated on the surface of the electrode sheet, while in Comparative Example 1, dendritic lithium has been formed after 100 charge-discharge cycles. Thus, it can be shown that for the half-cell prepared by the method of the present invention, a uniform solid electrolyte interface is formed between the electrode sheet and the solid electrolyte; from Figure 1 and Figure 2 it can also be seen that there are obvious differences in the state of the electrode sheet surface after 100 cycles. It can be clearly seen that after 100 cycles, the surface of the electrode sheet in Example 1 still remains clean and intact, and only a very small amount of filamentous lithium can be seen to be generated; while a large number of lithium dendrites have been formed on the surface of the electrode sheet in Comparative Example 1; from Figure 1 and Figure 2 it is not difficult to know from the comparison that for batteries composed of the same raw materials, the cycle life and capacity retention rate of the batteries prepared by the method of the present invention will be significantly improved.

[0093] The above description is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present invention, may make some changes or modifications to the above-mentioned technical content to obtain equivalent embodiments of equivalent changes. The implementation schemes in the above embodiments can also be further combined or replaced. However, as long as the content does not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the present invention.

Claims

1. A method for regulating the solid electrolyte interface of an all-solid-state secondary battery, characterized in that, The assembled battery cell is charged and then pressed; Before pressing the battery cell, it at least includes a first charging stage; In the first charging stage, it is charged at a charging rate of 0.005-0.015C until the capacity reaches 0.5%-2% SOC, and then pressed at a pressure of 0.5-2 MPa. Compared with before the pressing starts, the thickness of the battery cell is reduced by 10-30% after pressing.

2. The method for regulating the solid electrolyte interface of the all-solid-state secondary battery according to claim 1, characterized in that The battery cell is pressed under the condition of a preset temperature.

3. The method for regulating the solid electrolyte interface of the all-solid-state secondary battery according to claim 2, wherein The preset temperature is higher than the charging temperature during the charging process before pressing.

4. The method for regulating the solid electrolyte interface of the all-solid-state secondary battery according to claim 2, wherein The preset temperature is 5-20°C higher than the charging temperature during the charging process before pressing.

5. The method for regulating the solid electrolyte interface of an all-solid-state secondary battery according to any one of claims 2-4, characterized in that The preset temperature satisfies: Y + 5°C ≤ X ≤ Y + 20°C where X is the preset temperature; Y is the lowest value of the melting limit in the solid electrolyte interface formed before pressing.

6. The method for regulating the solid electrolyte interface of the all-solid-state secondary battery according to claim 1, wherein The assembled battery cell is alternately charged and pressed.

7. The method for regulating the solid electrolyte interface of the all-solid-state secondary battery according to claim 6, wherein Arranged according to the charging time sequence, the subsequent pressing pressure is greater than the previous pressing pressure.

8. The method for regulating the solid electrolyte interface of the all-solid-state secondary battery according to claim 6, characterized in that Arranged according to the charging time sequence, the subsequent pressing temperature is greater than the previous pressing temperature.

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