All-solid-state battery and formation method thereof

Abstract

The invention relates to the technical field of batteries, in particular to an all-solid-state battery and a formation method thereof. The formation method comprises the following steps: applying pressure P1 to the surface of the battery, and charging and discharging at the temperature T1; the parameters are adjusted, the charging and discharging steps are repeated, n times of charging and discharging are carried out, in the ith charging and discharging process, the pressure applied to the surface of the battery is Pi, the temperature is Ti, and i is larger than or equal to 1 and smaller than or equal to n-1; in the nth charging and discharging process, the pressure Pn applied to the surface of the battery is working condition pressure, and under the condition that the temperature is Tn, constant-current charging is carried out to 100% SOC, and then constant-current discharging is carried out to 0% SOC; wherein Pi is greater than or equal to Pi + 1, and pressure drop is performed at least twice from P1 to Pn. The formation system that the surface pressure of the battery is reduced from the high pressure gradient to the working condition pressure is adopted, compact low-resistance electrolyte membranes can be generated on the positive electrode, the negative electrode and the electrolyte interface, the interface impedance is reduced, and the cycle performance of the material is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to an all-solid-state battery and a formation method thereof. Background Art

[0002] As lithium-ion battery technology matures, the development of new high-performance batteries has become an urgent need for industry development. Solid-state batteries are considered an important technical route for the next generation of power batteries. The formation process is a key step in the battery manufacturing process. An excellent formation system helps to form a high-quality reaction interface and activate the capacity of the main material to obtain a high-performance battery. Compared with liquid batteries and semi-solid batteries, all-solid-state batteries do not have the risk of leakage due to the lack of liquid. The batteries have higher thermal stability and a wider operating temperature range; however, there are more significant interface problems due to solid-solid contact.

[0003] The patent application with announcement number CN 118712532 A discloses a solid-state battery formation method to improve the cycle performance and rate performance of solid-state batteries. By adopting a method of alternating in-situ electrolyte polymerization and formation process for the solid-state battery, a small current is charged in the early stage of formation to form an SEI film on the negative electrode. After thermally induced electrolyte polymerization, the solid electrolyte generated by in-situ polymerization inside the battery cell can grow directly on the SEI film. The SEI film and the solid electrolyte can form a tightly bonded solid-solid interface. In the process of continuing low-current charging after polymerization, the degree of fit of the solid-solid interface can be further improved. However, this method is more suitable for in-situ solidification batteries and does not meet the requirements of all-solid-state batteries.

[0004] For all-solid-state batteries, the electrochemical performance is poor when formed at relatively low pressures. While formation at high pressures can improve electrochemical performance, the pressures are far higher than those required for actual application scenarios and are incompatible with the actual operating conditions of power batteries. Therefore, it is of great significance to optimize the formation process for all-solid-state batteries, gradually transition the surface pressure of solid-state batteries from preparation conditions to actual application pressure conditions, and obtain an excellent solid-solid contact interface to improve the electrochemical performance of all-solid-state batteries.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The first purpose of the present invention is to provide a formation method for an all-solid-state battery. The present invention adopts a step-by-step formation system, which is conducive to generating a dense low-resistance electrolyte membrane at the interface between the positive and negative electrodes and the electrolyte, reducing the interface impedance and improving the cycle performance of the material.

[0007] The second object of the present invention is to provide an all-solid-state battery, which is manufactured using the all-solid-state battery formation method as described above.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: A formation method for an all-solid-state battery comprises the following steps: Apply uniform pressure P1 to the battery surface, charge the battery to V1-1 at a constant current at a temperature of T1, and then discharge the battery to V1-2 at a constant current. Adjust the parameters and repeat the above charge and discharge steps for a total of n charge and discharge cycles. During the i-th charge and discharge cycle, the pressure applied to the battery surface is Pi, the temperature is Ti, the charge cut-off voltage is Vi-1, and the discharge cut-off voltage is Vi-2, where 1≤i≤n-1. During the nth charge and discharge process, the pressure Pn applied to the surface of the battery is the operating pressure. Under the condition of temperature Tn, the battery is charged to 100% SOC at a constant current and then discharged to 0% SOC at a constant current. Among them, Pi≥Pi+1, and there are at least two pressure drops from P1 to Pn.

[0009] Preferably, the operating pressure is 2kPa~10MPa.

[0010] Preferably, during any pressure drop process, the pressure drop ranges from 1 MPa to 90 MPa.

[0011] Preferably, the pressure P1 applied to the battery surface during the first charge and discharge process and the pressure Pn applied to the battery surface during the nth charge and discharge process satisfy the following relationship: 5MPa≤P1-Pn≤170MPa.

[0012] Preferably, during any charge and discharge process, the charge rate is 0.01~1C, and the discharge rate is 0.01~1C.

[0013] Preferably, during the i-th charge and discharge process, the charge cut-off voltage Vi-1 is higher than the oxidation potential of the electrolyte and lower than the voltage corresponding to 100% SOC; the discharge cut-off voltage Vi-2 is not lower than the discharge cut-off voltage of the operating condition; wherein 1≤i≤n-1.

[0014] Preferably, the temperature during any charge and discharge process is 10-200°C.

[0015] Preferably, the number of charge and discharge cycles n is 3 to 5 times.

[0016] Preferably, during any charge and discharge process, the pressure and temperature equilibrium time is 5 minutes to 24 hours.

[0017] An all-solid-state battery is produced using the all-solid-state battery formation method described in any one of the aforementioned embodiments.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The step-by-step pressure reduction formation system provided by the present invention first uses a relatively high pressure to perform constant current charging on the battery to a specific voltage, generating a dense, high-quality interface film while ensuring good solid-solid contact conditions, and then gradually reduces the battery surface pressure to an operating value within a certain SOC range to controllably generate a solid-solid interface film and improve battery operation stability. The prepared battery also has good electrochemical performance under low operating pressure, and the battery's discharge specific capacity and capacity retention rate are improved. The method has simple process conditions and is suitable for large-scale production and development. DETAILED DESCRIPTION

[0019] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0020] A first aspect of the present invention provides a formation method for an all-solid-state battery, comprising the following steps: Apply uniform pressure P1 to the battery surface, charge the battery to V1-1 at a constant current at a temperature of T1, and then discharge the battery to V1-2 at a constant current. Adjust the parameters and repeat the above charge and discharge steps for a total of n charge and discharge cycles. During the i-th charge and discharge process, the pressure applied to the battery surface is Pi, the temperature is Ti, the charge cut-off voltage is Vi-1, and the discharge cut-off voltage is Vi-2, 1≤i≤n-1; During the nth charge and discharge process, the pressure Pn applied to the battery surface is the operating pressure. Under the condition of temperature Tn, constant current charging is performed to 100% SOC, and then constant current discharge is performed to 0% SOC. Among them, Pi≥Pi+1, and there are at least two pressure drops from P1 to Pn.

[0021] In the formation process of the present invention, after n charge and discharge processes, the pressure applied to the battery surface in the latter charge and discharge process is less than the pressure applied to the battery surface in the former charge and discharge process, or is equal to the pressure applied to the battery surface in the former charge and discharge process, and the pressure P1 applied to the battery surface in the first charge and discharge process undergoes at least two pressure drops to reach the operating pressure Pn in the nth charge and discharge process; first, the battery is charged to a specific voltage at a higher pressure by constant current, and a dense high-quality interface film is generated while ensuring good solid-solid contact; then, the battery surface pressure is gradually reduced to the operating value within a certain SOC range, so as to controllably generate the solid-solid interface film and improve the battery operation stability; the present invention improves the discharge specific capacity and cycle stability of an all-solid-state battery at low operating pressure through a step-by-step pressure drop formation process, and improves the electrochemical performance of the all-solid-state battery; and the method has simple process conditions and is suitable for large-scale production and development.

[0022] In some specific embodiments of the present invention, the operating pressure during the nth charge and discharge process is 2 kPa~10 MPa, for example, it can be any point value among 2 kPa, 3 MPa, 5 MPa, 7 MPa, 9 MPa, 10 MPa, or a range value consisting of any two point values.

[0023] In some specific embodiments of the present invention, during any pressure drop process, the pressure drop range is 1 MPa~90 MPa. For example, it can be any point value among 1 MPa, 3 MPa, 5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, or a range value consisting of any two point values.

[0024] In some specific embodiments of the present invention, the pressure P1 applied to the battery surface during the first charge and discharge process and the pressure Pn applied to the battery surface during the n-th charge and discharge process satisfy the following relationship: 5MPa≤P1-Pn≤170MPa. For example, the difference between P1 and Pn can be any point value among 5MPa, 10MPa, 20MPa, 30MPa, 40MPa, 50MPa, 70MPa, 100MPa, 120MPa, 150MPa, and 170MPa, or a range value consisting of any two point values. If the difference between P1 and Pn is too small, the pressure applied to the battery surface during the entire formation process is relatively small, that is, the formation is carried out at low pressure, and it is difficult to effectively improve the contact conditions of the solid-solid interface. All-solid-state batteries have extremely high requirements for the contact between the electrode and the solid electrolyte. If the pressure is insufficient, poor interface contact will lead to a significant increase in contact resistance, affecting the battery's charge and discharge efficiency; the ion conductivity of the solid electrolyte depends on good interface contact, and insufficient pressure may also lead to poor ion channels, reducing the overall performance of the battery; if the difference between P1 and Pn is too large, it means that the pressure applied to the battery surface is significantly higher than the pressure under actual working conditions, which may cause damage to the battery structure.

[0025] In some specific embodiments of the present invention, during any charge and discharge process, the charge rate is 0.01~1C, for example, the charge rate can be any point value among 0.01C, 0.1C, 0.3C, 0.5C, 0.8C, and 1C, or a range value consisting of any two point values; the discharge rate is 0.01~1C, for example, the discharge rate can be any point value among 0.01C, 0.1C, 0.3C, 0.5C, 0.8C, and 1C, or a range value consisting of any two point values; the charge rate in different charge and discharge stages can be the same or different; the discharge rate in different charge and discharge stages can be the same or different.

[0026] In some specific embodiments of the present invention, during the i-th charge and discharge process, the charge cut-off voltage Vi-1 is higher than the voltage corresponding to the electrolyte oxidation potential and lower than 100% SOC; the discharge cut-off voltage Vi-2 is not lower than the discharge cut-off voltage during operating mode; 1 ≤ i ≤ n-1. The charge cut-off voltages during different charge and discharge processes can be the same or different; and the discharge cut-off voltages during different charge and discharge processes can be the same or different.

[0027] In some specific embodiments of the present invention, the temperature during any charge and discharge process is 10~200°C, for example, it can be any point value among 10°C, 20°C, 25°C, 45°C, 60°C, 80°C, 100°C, 150°C, and 200°C, or a range value consisting of any two point values; the temperature in different charge and discharge stages can be the same or different.

[0028] In some specific embodiments of the present invention, the number of charge and discharge times n in the formation process is not less than 3 times, preferably 3 to 5 times, for example, 3 times, 4 times or 5 times. Too many charge and discharge times will lead to a decrease in formation efficiency.

[0029] In some specific embodiments of the present invention, during any charge and discharge process, the pressure and temperature equilibrium time is 5 minutes to 24 hours. For example, it can be any point value among 5 minutes, 30 minutes, 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, and 24 hours, or a range value consisting of any two point values.

[0030] A second aspect of the present invention provides an all-solid-state battery, which is manufactured using the all-solid-state battery formation method described in any one of the aforementioned embodiments.

[0031] The following describes some embodiments of the present invention in detail, with reference to specific application examples. The raw materials used in these examples can be purchased commercially unless otherwise specified. The positive electrode used is a high-nickel ternary material (half-cell specific capacity 214 mAh / g), the negative electrode is a SiO material (half-cell specific capacity 1300 mAh / g), and the solid electrolyte is a sulfide electrolyte (electrochemical window 1.5-2.5 V). The mass ratio of active material, electrolyte, glue, and conductive agent in the positive electrode is 65:31:2:2, and the mixture is uniformly coated on both sides of aluminum foil. The mass ratio of active material, electrolyte, glue, and conductive agent in the negative electrode is 67:27:3:3, and the mixture is uniformly coated on both sides of copper foil. The mass ratio of solid electrolyte to glue in the electrolyte membrane is 98:2, and the mixture is uniformly coated on the support material. After film formation, the membrane is transferred to the surface of the negative electrode. The negative electrode sheet, electrolyte membrane, and positive electrode sheet are stacked in the order of negative electrode / electrolyte membrane / positive electrode / negative electrode / electrolyte membrane / positive electrode to form the tested all-solid-state battery.

[0032] Example 1 This embodiment discloses a formation method of an all-solid-state battery, comprising the following steps: Step 1: Pressurize the prepared solid-state battery upper fixture to 180 MPa, keep the ambient temperature at 25°C, let it stand for 1 hour, and place it on the formation cabinet; at 25°C, charge the battery at a constant current of 0.1C to 3.7V, and then discharge it at a constant current of 0.1C to 2.5V; Step 2: Adjust the battery surface pressure to 90 MPa and the ambient temperature to 25°C, and let it stand for 1 hour; at 25°C, charge the battery at a constant current and constant voltage of 0.1C to 3.7V, and then discharge it at a constant current of 0.1C to 2.5V; Step 3: Adjust the battery surface pressure to 10 MPa and the ambient temperature to 25°C, and let it stand for 1 hour; at 25°C, charge the above battery at a constant current and constant voltage of 0.1C charging rate to 4.2V, and then discharge it at a constant current of 0.1C discharge rate to 2.5V.

[0033] Comparative Example 1 The prepared all-solid-state battery upper fixture was pressurized to 10 MPa and left to stand for 1 hour. At 25°C, the battery was charged to 3.7V at a constant current at a charging rate of 0.1C, and then discharged to 2.5V at 0.1C. After charging and discharging twice in the voltage range of 3.7-2.5V, the battery was charged to 4.2V at a constant current at a charging rate of 0.1C, and then discharged to 2.5V at 0.1C.

[0034] Example 2 This embodiment discloses a formation method of an all-solid-state battery, comprising the following steps: Step 1: Pressurize the prepared solid-state battery upper fixture to 60 MPa, keep the ambient temperature at 25°C, let it stand for 5 hours, and place it on the formation cabinet; at 25°C, charge the battery at a constant current of 0.1C to 3.8V, and then discharge it at a constant current of 0.1C to 2.5V; Step 2: Adjust the battery surface pressure to 20 MPa and the ambient temperature to 45°C, and let it stand for 1 hour; at 45°C, charge the battery at a constant current of 0.1C to 3.8V, and then discharge it at a constant current of 0.1C to 2.5V; Step 3: Adjust the battery surface pressure to 10 MPa and the ambient temperature to 45°C, and let it stand for 1 hour; at 45°C, charge the battery at a constant current of 0.1C to 4.2V, and then discharge it at a constant current of 0.1C to 2.5V.

[0035] Comparative Example 2 The prepared all-solid-state battery upper fixture was pressurized to 10 MPa, the ambient temperature was 25°C, and it was left to stand for 5 hours and placed on a formation cabinet. At 25°C, the above battery was charged to 3.8 V at a constant current at a 0.1C charge rate, and then discharged to 2.5 V at a constant current at a 0.1C discharge rate.

[0036] The battery surface pressure was maintained at 10 MPa, the ambient temperature was adjusted to 45°C, and the battery was left to stand for 1 hour. At 45°C, the battery was charged at a constant current and constant voltage of 0.1C at a charge rate to 3.8V, and then discharged at a constant current of 0.1C at a discharge rate to 2.5V. The battery surface pressure was maintained at 10 MPa and the ambient temperature was maintained at 45° C. The battery was charged at a constant current of 0.1 C to 4.2 V, and then discharged at a constant current of 0.1 C to 2.5 V.

[0037] Example 3 This embodiment discloses a formation process for an all-solid-state battery, comprising the following steps: Step 1: Pressurize the prepared solid-state battery upper fixture to 80 MPa and place it on the formation cabinet; at 25°C, charge the battery at a constant current of 0.1C to 3.75V, and then discharge it at a constant current of 0.1C to 2.5V; Step 2: Adjust the battery surface pressure to 60 MPa and the ambient temperature to 45°C, and let it stand for 5 hours; at 45°C, charge the battery at a constant current of 0.1C to 3.75V, and then discharge it at a constant current of 0.1C to 2.5V; Step 3: Adjust the battery surface pressure to 30 MPa and the ambient temperature to 60°C, and let it stand for 5 hours; at 60°C, charge the battery at a constant current of 0.1C to 3.75V, and then discharge it at a constant current of 0.1C to 2.5V; Step 4: Adjust the battery surface pressure to 10 MPa and the ambient temperature to 60°C, and let it stand for 5 hours; at 60°C, charge the battery at a constant current of 0.1C to 3.75V, and then discharge it at a constant current of 0.1C to 2.5V; Step 5. Adjust the battery surface pressure to 8 MPa and the ambient temperature to 25°C, and let it stand for 5 hours. At 25°C, charge the battery at a constant current of 0.1C to 4.2V, and then discharge it at a constant current of 0.1C to 2.5V.

[0038] Comparative Example 3 The prepared solid-state battery upper fixture was pressurized to 8 MPa and placed on a formation cabinet. At 25°C, the battery was charged at a constant current of 0.1C to 3.75V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 8 MPa and the ambient temperature was 45°C, and the battery was left to stand for 5 hours. At 45°C, the battery was charged at a constant current of 0.1C to 3.75V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 8 MPa and the ambient temperature was maintained at 60°C, and the battery was left to stand for 5 hours. At 60°C, the battery was charged at a constant current of 0.1C to 3.75V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 8 MPa and the ambient temperature was maintained at 60°C, and the battery was left to stand for 5 hours. At 60°C, the battery was charged at a constant current of 0.1C to 3.75V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was adjusted to 8 MPa, the ambient temperature was 25°C, and the battery was left to stand for 5 h. At 25°C, the battery was charged to 4.2 V at a constant current at a 0.1C charge rate, and then discharged to 2.5 V at a constant current at a 0.1C discharge rate.

[0039] Example 4 This embodiment discloses a formation process for an all-solid-state battery, comprising the following steps: Step 1: Pressurize the prepared solid-state battery upper fixture to 60 MPa, place it on a formation cabinet, and let it stand for 10 hours; at 25°C, charge the battery at a constant current of 0.1C to 3.65V, and then discharge it at a constant current of 0.1C to 2.5V; Step 2: Set the battery surface pressure to 60 MPa and the ambient temperature to 45°C, and let it stand for 5 hours; at 45°C, charge the battery at a constant current of 0.1C to 3.65V, and then discharge it at a constant current of 0.1C to 2.5V; Step 3: Set the battery surface pressure to 60 MPa and the ambient temperature to 60°C, and let it stand for 5 hours; at 60°C, charge the battery at a constant current of 0.1C to 3.65V, and then discharge it at a constant current of 0.1C to 2.5V; Step 4: Set the battery surface pressure to 30 MPa and the ambient temperature to 45°C, and let it stand for 5 hours. At 45°C, charge the battery at a constant current of 0.1C to 3.65V, and then discharge it at a constant current of 0.1C to 2.5V. Step 5. Set the battery surface pressure to 5 MPa and the ambient temperature to 25°C, and let it stand for 5 hours. At 25°C, charge the battery to 4.2V at a constant current and constant voltage at a charge rate of 0.1C, and then discharge it to 2.5V at a constant current and constant voltage at a discharge rate of 0.1C.

[0040] Comparative Example 4 The prepared solid-state battery upper fixture was pressurized to 5 MPa, placed on a formation cabinet, and left to stand for 10 h. At 25°C, the battery was charged at a constant current of 0.1C to 3.65 V, and then discharged at a constant current of 0.1C to 2.5 V. The battery surface pressure was maintained at 5 MPa and the ambient temperature was 45°C, and the battery was left to stand for 5 hours. At 45°C, the battery was charged at a constant current of 0.1C to 3.65V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 5 MPa and the ambient temperature was 60°C, and the battery was left to stand for 5 hours. At 60°C, the battery was charged at a constant current of 0.1C to 3.65V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 5 MPa and the ambient temperature was 45°C, and the battery was left to stand for 5 hours. At 45°C, the battery was charged at a constant current and constant voltage of 0.1C at a charge rate to 3.65V, and then discharged at a constant current of 0.1C at a discharge rate to 2.5V. The battery surface pressure was maintained at 5 MPa and the ambient temperature was maintained at 25°C for 5 h. At 25°C, the battery was charged at a constant current and constant voltage of 0.1C at a charge rate to 4.2V, and then discharged at a constant current of 0.1C at a discharge rate to 2.5V.

[0041] Comparative Example 5 Comparative Example 5 is similar to Example 4, with the only difference being that the pressure applied to the battery surface during the five charge and discharge processes is 60 MPa, and the other conditions are the same as those in Example 4.

[0042] Comparative Example 6 The prepared solid-state battery upper fixture was pressurized to 5 MPa, placed on a formation cabinet, and left to stand for 10 h. At 25°C, the battery was charged at a constant current of 0.1C to 3.65 V, and then discharged at a constant current of 0.1C to 2.5 V. The battery surface pressure was maintained at 10 MPa and the ambient temperature was 45°C, and the battery was left to stand for 5 hours. At 45°C, the battery was charged at a constant current of 0.1C to 3.65V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 20 MPa and the ambient temperature was 60°C, and the battery was left to stand for 5 hours. At 60°C, the battery was charged at a constant current of 0.1C to 3.65V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 10 MPa and the ambient temperature was 45°C for 5 h. At 45°C, the battery was charged at a constant current of 0.1C to 3.65V, and then discharged at a constant current of 0.1C to 2.5V. The battery surface pressure was maintained at 5 MPa and the ambient temperature was maintained at 25°C for 5 h. At 25°C, the battery was charged at a constant current of 0.1C to 4.2V, and then discharged at a constant current of 0.1C to 2.5V.

[0043] Comparative Example 7 Comparative Example 7 is similar to Example 4, with the only difference being that the pressure applied to the battery surface during the first four charge and discharge processes is 8 MPa, and the pressure applied to the battery surface during the fifth charge and discharge process is 5 MPa. The other conditions are the same as those in Example 4.

[0044] Test example (1) The first discharge specific capacity of the positive electrode material, the second-week battery cycle efficiency, and the 100-week capacity retention rate of the batteries formed in Example 1 and Comparative Example 1 were tested under the conditions of 25°C, 10 MPa, and 0.1C current charge and discharge; (2) The first discharge specific capacity of the positive electrode material, the second-week battery cycle efficiency, and the 100-week capacity retention rate of the batteries formed in Example 2 and Comparative Example 2 were tested under the conditions of 45°C, 10 MPa, and 0.1C current charge and discharge; (3) The first discharge specific capacity of the positive electrode material, the second-week battery cycle efficiency, and the 100-week capacity retention rate of the batteries formed in Example 3 and Comparative Example 3 were tested under the conditions of 25°C, 8 MPa, and 0.1C current charge and discharge; (4) The first discharge specific capacity of the positive electrode material, the second-week battery cycle efficiency, and the 100-week capacity retention rate of the batteries formed in Example 4 and Comparative Examples 4-7 were tested under the conditions of 25°C, 5 MPa, and 0.1C current charge and discharge; The test results are shown in Table 1.

[0045] Table 1

[0046] It can be seen from the data in Table 1 that when the external pressure is high, the contact between the material particles inside the battery is better, which is conducive to the formation of a more complete solid-solid interface and a higher material capacity during battery formation; under lower pressure, due to the volume expansion of the material during the battery charging and discharging process, the electrode structure will undergo significant changes, and the material capacity and battery capacity retention rate will decrease; the gradual transition from high-pressure experimental conditions to low-pressure actual working conditions is conducive to the controllable changes of the solid-solid interface and electrode structure, which helps to improve the capacity and cycle performance of the battery under low-pressure conditions.

[0047] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A formation method of an all-solid-state battery, characterized in that: The following steps are involved: Apply pressure P1 to the battery surface, charge the battery to V1-1 at a constant current at a temperature of T1, and then discharge the battery to V1-2 at a constant current. Adjust the parameters and repeat the above charge and discharge steps for a total of n charge and discharge cycles. During the i-th charge and discharge cycle, the pressure applied to the battery surface is Pi, the temperature is Ti, the charge cut-off voltage is Vi-1, and the discharge cut-off voltage is Vi-2, where 1≤i≤n-1. During the nth charge and discharge process, the pressure Pn applied to the surface of the battery is the operating pressure. Under the condition of temperature Tn, the battery is charged to 100% SOC at a constant current and then discharged to 0% SOC at a constant current. Among them, Pi≥Pi+1, and there are at least two pressure drops from P1 to Pn.

2. The formation method of an all-solid-state battery according to claim 1, characterized in that: The working pressure is 2kPa~10MPa.

3. The formation method of an all-solid-state battery according to claim 1, characterized in that: During any pressure drop process, the pressure drop range is 1MPa~90MPa.

4. The formation method of an all-solid-state battery according to claim 1, characterized in that: The pressure P1 applied to the battery surface during the first charge and discharge process and the pressure Pn applied to the battery surface during the nth charge and discharge process satisfy the following relationship: 5MPa≤P1-Pn≤170MPa.

5. The formation method of an all-solid-state battery according to claim 1, characterized in that: During any charge and discharge process, the charge rate is 0.01~1C, and the discharge rate is 0.01~1C.

6. The formation method of an all-solid-state battery according to claim 1, characterized in that: During the i-th charge and discharge process, the charge cut-off voltage Vi-1 is higher than the oxidation potential of the electrolyte and lower than the voltage corresponding to 100% SOC; the discharge cut-off voltage Vi-2 is not lower than the operating condition discharge cut-off voltage; among them, 1≤i≤n-1.

7. The formation method of an all-solid-state battery according to claim 1, characterized in that: The temperature during any charge and discharge process is 10~200℃.

8. The formation method of an all-solid-state battery according to claim 1, characterized in that: The number of charge and discharge times n is 3 to 5 times.

9. The formation method of an all-solid-state battery according to claim 1, characterized in that: During any charge and discharge process, the pressure and temperature equilibrium time is 5 minutes to 24 hours.

10. An all-solid-state battery, characterized in that: The battery is prepared by the formation method of the all-solid-state battery according to any one of claims 1 to 9.

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