Capacity grading method for all-solid-state battery

Abstract

The invention provides an all-solid-state battery capacity grading method which comprises the following steps: placing a battery in a capacity grading cabinet, and controlling the internal temperature of the capacity grading cabinet to reach a first preset temperature; performing low-current discharging operation on the battery at the first preset temperature, so that the voltage of the battery is reduced to a first preset voltage; low-current charging operation is carried out on the battery, so that the voltage of the battery is increased to a second preset voltage, and the second preset voltage is larger than the first preset voltage; the internal temperature of the capacity grading cabinet is controlled to be reduced to a second preset temperature, large-current charging operation is carried out on the battery, the voltage of the battery is made to be increased to a third preset voltage, and the third preset voltage is larger than the second preset voltage; controlling the internal temperature of the capacity grading cabinet to rise to a first preset temperature, discharging the battery, and reducing the voltage of the battery to a first preset voltage; and charging the battery to enable the voltage of the battery to meet the preset K value test voltage, and ending the capacity grading operation. By applying the method, the internal polarization degree of the battery in the charge-discharge process during capacity grading can be reduced, and the capacity grading process time is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of battery capacity division, and in particular to a method for all-solid-state battery capacity division. Background Art

[0002] In recent years, lithium-ion batteries have been widely used in various fields such as electronic products due to their excellent properties such as high energy density, high voltage, high cycle, high safety, and green environmental protection. Among them, all-solid-state batteries have become a major direction for the future development of lithium-ion batteries due to their high safety, wide operating temperature range, and high energy density. Compared with liquid batteries, all-solid-state batteries are currently in their infancy and do not have a fixed set of process flows. Especially for the middle and later stages of battery production, the processes of major manufacturers are different. Among them, the capacity division process is the top priority of the battery production process and has a great impact on the battery's later test performance. The capacity division stage usually requires multiple charge and discharge cycles, and the discharge capacity of this process is used as the standard for the battery pack. For this reason, battery manufacturers need to study and summarize the capacity division process and parameters that are suitable for them to ensure that the battery obtains the maximum capacity, the best stability, and the longest life.

[0003] Multiple charge and discharge cycles in the capacity division stage will greatly increase the production cycle of the battery and increase energy consumption. Therefore, it is necessary to shorten the capacity division process while meeting the electrochemical performance of the battery. In addition, polarization is inevitable during the charge and discharge process of lithium batteries. The capacity division process usually uses the method of leaving the battery to stand for a long time to deactivate it. The whole process is time-consuming and not conducive to high-efficiency production. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for all-solid-state battery capacity division, which can reduce the internal polarization degree of the battery during the charging and discharging process during capacity division and shorten the capacity division process time.

[0005] In order to achieve the above-mentioned main purpose, the all-solid-state battery capacity division method provided by the present invention includes: placing the battery in a capacity division cabinet, controlling the internal temperature of the capacity division cabinet to reach a first preset temperature; at the first preset temperature, performing a small current discharge operation on the battery to reduce the voltage of the battery to a first preset voltage; performing a small current charging operation on the battery to increase the voltage of the battery to a second preset voltage, and the second preset voltage is greater than the first preset voltage; controlling the internal temperature of the capacity division cabinet to drop to the second preset temperature, performing a large current charging operation on the battery, and increasing the voltage of the battery to a third preset voltage, wherein the third preset voltage is greater than the second preset voltage; controlling the internal temperature of the capacity division cabinet to rise to the first preset temperature, performing a discharge operation on the battery, and reducing the voltage of the battery to the first preset voltage; performing a charging operation on the battery, and making the voltage of the battery meet the preset K value test voltage, and ending the capacity division operation.

[0006] As can be seen from the above scheme, the all-solid-state battery capacity division method of the present invention first adopts a small current discharge, which is conducive to completely emptying the battery and greatly eliminating the influence of polarization. Then a small current is charged to reduce the damage to the positive electrode material lattice and stabilize the contact surface between the solid electrolyte and the positive and negative electrode materials. Then the temperature is lowered, and the current is increased to shorten the charging time, reduce polarization, increase the charging cut-off voltage, and completely open the closed pores of the positive electrode material, increase the release of lithium ions, and improve the capacity, thereby greatly reducing the internal polarization of the battery and shortening the capacity division process time.

[0007] In a further solution, the step of performing a low-current discharge operation on the battery includes: controlling the battery to perform constant-current discharge at a first preset discharge rate, and the discharge duration is the first preset discharge duration.

[0008] It can be seen that constant current discharge at the first preset discharge rate is beneficial to completely discharge the battery and greatly eliminate the influence of polarization.

[0009] In a further embodiment, the step of discharging the battery includes: controlling the battery to perform constant current discharge at a second preset discharge rate, the discharge duration is the second preset discharge duration, and the second preset discharge rate is greater than the first preset discharge rate.

[0010] It can be seen that constant current discharge at the second preset discharge rate can enable the negative electrode to release sufficient lithium ions during discharge to quickly embed into the fully activated positive electrode, ultimately increasing the split capacity.

[0011] In a further embodiment, the first preset discharge rate is 0.05C to 0.1C, and the second preset discharge rate is 0.3C to 0.5C.

[0012] It can be seen that the first preset discharge rate is 0.05C to 0.1C, and the second preset discharge rate is 0.3C to 0.5C, which can optimize the discharge effect.

[0013] In a further solution, the step of performing a low-current charging operation on the battery includes: controlling the battery to perform constant-current charging at a first preset charging rate, and the charging time is the first preset charging time.

[0014] It can be seen that constant current charging at the first preset charging rate to achieve initial small current charging is beneficial to reduce the damage to the positive electrode material lattice and stabilize the contact surface between the solid electrolyte and the positive and negative electrode materials.

[0015] In a further scheme, the step of performing a high current charging operation on the battery includes: controlling the battery to perform constant current and constant voltage charging at a second preset charging rate, the cutoff current is the preset cutoff current, the charging time is the second preset charging time, and the second preset charging rate is greater than the first preset charging rate.

[0016] It can be seen that constant current and constant voltage charging at the second preset charging rate can increase the charging current, shorten the charging time, and reduce polarization.

[0017] In a further embodiment, the first preset charging rate is 0.25C to 0.35C, the second preset charging rate is 0.6C to 0.8C, and the preset cut-off current is 0.02C to 0.05C.

[0018] It can be seen that the first preset charging rate is 0.25C to 0.35C, and the second preset charging rate is 0.6C to 0.8C, which can optimize the charging effect.

[0019] In a further solution, before placing the battery in the capacity distribution cabinet, the method further includes: using a clamp to pressurize and fix the battery, and the pressure between the plates is a preset pressure value.

[0020] It can be seen that pressurizing and fixing the battery by clamping can effectively reduce the gap between the solid electrolyte and the positive and negative electrode interfaces, thereby reducing the internal resistance of the battery.

[0021] In a further scheme, after the internal temperature of the capacity distribution cabinet reaches a first preset temperature, the battery is controlled to perform a small current discharge operation after a first preset time period; and / or after the battery is controlled to perform a small current discharge operation, the battery is controlled to perform a small current charging operation after a second preset time period; and / or after the internal temperature of the capacity distribution cabinet is controlled to drop to the second preset temperature, the battery is controlled to perform a large current charging operation after a third preset time period; and / or after the internal temperature of the capacity distribution cabinet is controlled to rise to the first preset temperature, the battery is discharged after a fourth preset time period; and / or after the battery is discharged, the battery is charged after a fifth preset time period.

[0022] It can be seen that after the first preset time is shelved, the battery is controlled to perform a small current discharge operation, which can ensure that the internal temperature of the battery reaches the first preset temperature before the capacity division operation is performed, thereby improving the capacity division effect. After the second preset time is shelved, the battery is controlled to perform a small current charging operation, which can ensure that the battery voltage is stable and does not fluctuate before discharging. After the third preset time is shelved, the internal temperature of the capacity division cabinet is controlled to drop to the second preset temperature, in order to ensure that the battery's own temperature drops from the first preset temperature to the second preset temperature, so as to improve the accuracy of capacity division. After the fourth preset time is shelved, the internal temperature of the capacity division cabinet is controlled to rise to the first preset temperature, in order to ensure that the battery's own temperature rises from the second preset temperature to the first preset temperature. After the fifth preset time is shelved, the battery is charged to ensure that the battery voltage is stable and does not fluctuate before discharging.

[0023] In a further solution, the first preset temperature is 80°C, the second preset temperature is 60°C, the first preset voltage is 2.5V to 2.7V, the second preset voltage is 3.77V, the third preset voltage is 4.4V, and the preset K value test voltage is 3.86V. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of an embodiment of the all-solid-state battery capacity division method of the present invention.

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0026] All-solid-state battery capacity division method embodiment:

[0027] like Figure 1 As shown, in this embodiment, when the all-solid-state battery capacity division method is working, step S1 is first performed, and the battery is pressurized and fixed by a clamp, and the pressure between the plates is a preset pressure value. Among them, the preset pressure value can be pre-set according to experimental data, and preferably, the preset pressure value is 4Mpa. In this embodiment, the clamp includes two upper and lower stainless steel plates, and the battery is clamped between the two stainless steel plates. Pressurizing and fixing the battery by clamping can effectively reduce the gap between the solid electrolyte and the positive and negative electrode interfaces, thereby reducing the internal resistance of the battery.

[0028] After the battery is pressurized and fixed with a clamp, step S2 is performed to place the battery in a capacity dividing cabinet, and the internal temperature of the capacity dividing cabinet is controlled to reach a first preset temperature. The capacity dividing cabinet can adopt a well-known temperature-controlled capacity dividing cabinet, which will not be described here. After the battery is placed in the capacity dividing cabinet, circuit connection is required to perform the capacity dividing operation. Therefore, the positive and negative pole connectors of the capacity dividing cabinet are connected to the positive and negative pole ears of the battery accordingly. In order to achieve a better battery capacity dividing effect, it is necessary to first control the internal temperature of the capacity dividing cabinet to reach a first preset temperature. At the first preset temperature, the ionic conductivity can be increased and the interface resistance can be reduced. At the same time, the chemical reaction rate can be accelerated and the stability of the battery capacity can be improved. In this embodiment, the first preset temperature is 80°C.

[0029] After the internal temperature of the capacity dividing cabinet reaches the first preset temperature, it is left for a first preset time. The first preset time is 20 minutes. Leaving for the first preset time can ensure that the capacity dividing operation is performed when the internal temperature of the battery reaches 80°C, thereby improving the effect of the capacity dividing.

[0030] After the first preset time is left, step S3 is executed to discharge the battery with a small current at a first preset temperature, so that the voltage of the battery drops to a first preset voltage. The first preset voltage is 2.5V to 2.7V, and preferably, the first preset voltage is 2.5V. Using a small current discharge is conducive to completely discharging the battery and greatly eliminating the influence of polarization.

[0031] In this embodiment, the step of controlling the battery to perform a low current discharge operation includes: controlling the battery to perform a constant current discharge at a first preset discharge rate, and the discharge duration is the first preset discharge duration. The first preset discharge rate is 0.05C to 0.1C, and preferably, the first preset discharge rate is 0.1C. The first preset discharge duration is 30 minutes.

[0032] After the voltage of the battery drops to the first preset voltage, it is left for a second preset time. The second preset time can be preset according to experimental data. The second preset time is 10 minutes. After the second preset time, it can be ensured that the battery voltage is in a stable and non-fluctuating state.

[0033] After the second preset time is left alone, step S4 is executed to perform a low-current charging operation on the battery, so that the voltage of the battery rises to a second preset voltage. The second preset voltage is greater than the first preset voltage, and preferably, the second preset voltage is 3.77 V. Performing a low-current charging operation on the battery can reduce the damage to the lattice of the positive electrode material and stabilize the contact surface between the solid electrolyte and the positive and negative electrode materials.

[0034] In this embodiment, the step of performing a low-current charging operation on the battery includes: controlling the battery to perform constant-current charging at a first preset charging rate, and the charging time is the first preset charging time. The first preset charging rate and the first preset charging time can be preset according to experimental data, wherein the first preset charging rate is 0.25C to 0.35C, preferably, the first preset charging rate is 0.3C, and the first preset charging time is 40 minutes.

[0035] After the voltage of the battery rises to the second preset voltage, step S5 is executed to control the internal temperature of the capacity distribution cabinet to drop to the second preset temperature, and the battery is charged with a large current to raise the voltage of the battery to the third preset voltage. The second preset temperature and the third preset voltage can be preset according to experimental data. Preferably, the second preset temperature is 60°C and the third preset voltage is 4.4V. Lowering the temperature and increasing the charging current can shorten the charging time, reduce polarization, increase the charging cut-off voltage, completely open the closed pores of the positive electrode material, increase the release of lithium ions, and improve the capacity.

[0036] In this embodiment, the step of performing a high-current charging operation on the battery includes: controlling the battery to perform constant-current and constant-voltage charging at a second preset charging rate, the cut-off current is a preset cut-off current, and the charging time is a second preset charging time. Among them, the second preset charging rate is greater than the first preset charging rate. The second preset charging rate and the preset cut-off current can be preset according to experimental data. The second preset charging rate is 0.6C to 0.8C, and preferably, the second preset charging rate is 0.7C. The preset cut-off current is 0.02C to 0.05C, and the preferred preset cut-off current is 0.03C. The second preset charging time is 60 minutes.

[0037] In this embodiment, after the internal temperature of the capacity distribution cabinet is controlled to drop to the second preset temperature, the battery is controlled to perform a high current charging operation after being shelved for a third preset time. The third preset time can be preset according to experimental data, and preferably, the third preset time is 20 minutes. Shelving for the third preset time can ensure that the temperature of the battery itself drops from the first preset temperature to the second preset temperature.

[0038] After the voltage of the battery is raised to the third preset voltage, step S6 is executed to control the internal temperature of the capacity distribution cabinet to rise to the first preset temperature, and the battery is discharged to reduce the voltage of the battery to the first preset voltage. When the battery is discharged, the negative electrode releases sufficient lithium ions and quickly embeds them into the fully activated positive electrode, thereby ultimately increasing the capacity distribution capacity. At the same time, the initial capacity data of the battery can also be obtained for subsequent testing.

[0039] In this embodiment, after the internal temperature of the capacity distribution cabinet is controlled to rise to the first preset temperature, the battery is discharged after being shelved for a fourth preset time, wherein the fourth preset time is 20 minutes. Shelving for the fourth preset time can ensure that the battery's own temperature rises from the second preset temperature to the first preset temperature.

[0040] In this embodiment, the step of discharging the battery includes: controlling the battery to perform constant current discharge at a second preset discharge rate, the discharge duration is the second preset discharge duration, and the second preset discharge rate is greater than the first preset discharge rate. The second preset discharge rate is 0.3C to 0.5C, preferably, the second preset discharge rate is 0.5C. The second preset discharge duration is 120 minutes.

[0041] In this embodiment, after the battery is discharged and the battery voltage drops to the first preset voltage, the fifth preset time is shelved, wherein the fifth preset time is 10 minutes, and the fifth preset time can ensure that the battery voltage is in a stable state without fluctuations.

[0042] After the fifth preset time is shelved, step S7 is executed to charge the battery so that the battery voltage meets the preset K value test voltage, and the capacity division operation is ended. The preset K value test voltage can be preset according to experimental data. Preferably, the preset K value test voltage is 3.86V. Charging the battery voltage to the preset K value test voltage can prepare for the later k value test. After the battery voltage meets the preset K value test voltage, the sixth preset time is shelved to complete the capacity division operation. The sixth preset time can be preset according to experimental data. Preferably, the sixth preset time is ten minutes.

[0043] As can be seen from the above, the all-solid-state battery capacity division method of the present invention first adopts a small current discharge, which is conducive to completely discharging the battery and greatly eliminating the influence of polarization. Then a small current is charged to reduce the damage to the positive electrode material lattice, while stabilizing the contact surface between the solid electrolyte and the positive and negative electrode materials. Then the temperature is lowered, and the current is increased to shorten the charging time, reduce polarization, increase the charging cut-off voltage, and completely open the closed pores of the positive electrode material, increase the release of lithium ions, and improve the capacity. Thereby greatly reducing the internal polarization of the battery and shortening the capacity division process time.

[0044] It should be noted that the above are only preferred embodiments of the present invention, but the design concept of the invention is not limited thereto, and any non-substantial modifications made to the present invention using this concept also fall within the protection scope of the present invention.

Claims

1. A method for all-solid-state battery capacity division, characterized in that: include: Placing the battery in a capacity distribution cabinet, and controlling the internal temperature of the capacity distribution cabinet to reach a first preset temperature; At the first preset temperature, controlling the battery to perform a small current discharge operation so that the voltage of the battery drops to a first preset voltage; Performing a low-current charging operation on the battery so that the voltage of the battery rises to a second preset voltage, wherein the second preset voltage is greater than the first preset voltage; Controlling the internal temperature of the capacity distribution cabinet to drop to a second preset temperature, performing a high-current charging operation on the battery, so that the voltage of the battery rises to a third preset voltage, wherein the third preset voltage is greater than the second preset voltage; Controlling the internal temperature of the capacity distribution cabinet to rise to the first preset temperature, and performing a discharge operation on the battery to reduce the voltage of the battery to the first preset voltage; The battery is charged so that the voltage of the battery meets the preset K value test voltage, and the capacity division operation is ended.

2. The all-solid-state battery capacity division method according to claim 1, characterized in that: The steps of performing a low current discharge operation on the battery include: The battery is controlled to perform constant current discharge at a first preset discharge rate, and the discharge duration is the first preset discharge duration.

3. The all-solid-state battery capacity division method according to claim 2, characterized in that: The steps of discharging the battery include: The battery is controlled to perform constant current discharge at a second preset discharge rate, the discharge duration is the second preset discharge duration, and the second preset discharge rate is greater than the first preset discharge rate.

4. The all-solid-state battery capacity division method according to claim 3, characterized in that: The first preset discharge rate is 0.05C to 0.1C, and the second preset discharge rate is 0.3C to 0.5C.

5. The all-solid-state battery capacity division method according to claim 1, characterized in that: The steps of controlling the battery to perform a low current charging operation include: The battery is controlled to perform constant current charging at a first preset charging rate, and the charging time is the first preset charging time.

6. The all-solid-state battery capacity division method according to claim 5, characterized in that: The steps of controlling the battery to perform a high current charging operation include: The battery is controlled to perform constant current and constant voltage charging at a second preset charging rate, the cut-off current is the preset cut-off current, the charging time is the second preset charging time, and the second preset charging rate is greater than the first preset charging rate.

7. The all-solid-state battery capacity division method according to claim 5, characterized in that: The first preset charging rate is 0.25C to 0.35C, the second preset charging rate is 0.6C to 0.8C, and the preset cut-off current is 0.02C to 0.05C.

8. The all-solid-state battery capacity division method according to any one of claims 1 to 7, characterized in that: Before placing the battery in the storage cabinet, it also includes: The battery is pressurized and fixed by a clamp, and the pressure between the plates is a preset pressure value.

9. The all-solid-state battery capacity division method according to any one of claims 1 to 7, characterized in that: After controlling the internal temperature of the capacity distribution cabinet to reach a first preset temperature, the battery is controlled to perform a small current discharge operation after being left for a first preset time; and / or After controlling the battery to perform a low-current discharge operation, pausing for a second preset time and then controlling the battery to perform a low-current charge operation; and / or After controlling the internal temperature of the capacity distribution cabinet to drop to a second preset temperature, the battery is controlled to perform a high current charging operation after being left for a third preset time; and / or After controlling the internal temperature of the capacity distribution cabinet to rise to the first preset temperature, the battery is discharged after being left for a fourth preset time; and / or After the battery is discharged, the battery is charged after a fifth preset time period.

10. The all-solid-state battery capacity division method according to any one of claims 1 to 7, characterized in that: The first preset temperature is 80° C., the second preset temperature is 60° C., the first preset voltage is 2.5V to 2.7V, the second preset voltage is 3.77V, the third preset voltage is 4.4V, and the preset K value test voltage is 3.86V.

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