Charging and discharging technology based on normal-temperature small-rate stepped constant-current charging and discharging repairing mode and secondary battery

Abstract

The invention discloses a charging and discharging technology based on a normal-temperature small-rate-step constant-current charging and discharging repairing mode and a secondary battery, belongs to the technical field of battery charging and discharging, and is characterized in that the battery is subjected to small-rate-step constant-current charging and discharging under a periodic normal-temperature condition in a circulating process. The charge-discharge technology can form an electrode / electrolyte interfacial film with excellent comprehensive properties, improve the cycle stability of the battery, improve the ion transport capability of the interfacial film and improve dynamics. Compared with a common charging and discharging technology, the charging and discharging technology can also remarkably prolong the cycle life of the battery under the all-weather condition.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to a charging and discharging technology and a secondary battery based on a normal temperature small rate step constant current charging and discharging repair method. Background Art

[0002] Since the first industrial revolution, fossil energy has supported the development of modern industry. However, huge carbon emissions have led to global warming, and unsustainability has brought about an energy crisis. Therefore, humans have been constantly exploring sustainable clean energy, such as solar and wind energy, and developing clean energy storage devices in the past half century. Among them, electrochemical energy storage devices have shown significant advantages with their high energy density, good reversibility, low cost and environmental friendliness, and occupy most of the market share. As a high-performance electrochemical energy storage device, lithium-ion batteries have become the main power source for electric vehicles.

[0003] By 2023, the market share of electric vehicles has reached more than 30%, but the long charging time (greater than 30 minutes) has always been the main obstacle to the large-scale application of electric vehicles. Therefore, fast charging characteristics, that is, charging to 80% SOC in less than 15 minutes, has become a key requirement for battery development. At present, electrochemical system design, charging method optimization or heating strategy are the main methods to achieve fast-chargeable batteries. Among them, charging method optimization (such as high-current charging, step charging and pulse charging) can regulate the ion transport process and shorten the charging time. However, high-current charging is prone to increase side reactions and accelerate performance degradation. Step charging cannot be optimized in time according to the changes in electrochemical properties during the life cycle. Pulse charging is prone to dendrite precipitation and reduce cycle performance. It can be seen that the development of new charging and discharging technologies in response to the challenges of optimizing the current main charging methods is of great practical significance to promote the development of electric vehicles and energy storage industries. Summary of the invention

[0004] The purpose of the present invention is to provide a charging and discharging technology and a secondary battery based on a small-rate step constant current charging and discharging repair method at room temperature. By adopting a small-rate step constant current charging and discharging repair strategy under periodic room temperature conditions during the battery cycle process, an electrode / electrolyte interface with excellent comprehensive properties is constructed, the interface stability and interface ion transfer kinetics are improved, and the performance of the battery in low temperature, room temperature and high temperature environments is improved.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A charging and discharging technology based on a small-rate step constant current charging and discharging repair method at room temperature. This technology uses a small-rate step constant current charging and discharging repair method under periodic room temperature conditions during the battery cycle process to improve the battery cycle stability and extend the battery cycle life.

[0007] Furthermore, the battery cycle process includes three types: constant current charge and discharge cycle, step constant current charge / constant current discharge cycle and pulse charge / constant current discharge cycle.

[0008] Furthermore, the constant current charge-discharge cycle method comprises the following steps (A1)-(A2):

[0009] (A1) Set the constant charging current I c , a constant discharge current I d , a charging cut-off voltage V max or a charge cut-off state of charge SOC max , a discharge cut-off voltage V min ;

[0010] (A2) The specific process of the constant current charge and discharge cycle is: the battery is charged at a constant current, and the charging current is I c , the charging cut-off voltage is V max Or the charging end state of charge is SOC max ; Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ; Repeat the constant current charging and constant current discharging cycles.

[0011] Furthermore, the step constant current charge / constant current discharge cycle method includes the following steps (B1)-(B2):

[0012] (B1) Set a set of gradually decreasing constant current charging current values ​​I c {I c1 ,I c2 ,I c3 ,……,I cn}, a set of gradually increasing constant current charging voltage values ​​V{V 1 ,V 2 ,V 3 ,.....,V n} or a set of gradually increasing constant current charging state of charge values ​​SOC{SOC 1 ,SOC 2 ,SOC 3 ,.....,SOC n}, a charging cut-off voltage V max or a charge cut-off state of charge SOC max , a discharge cut-off voltage V min ;

[0013] (B2) The specific process of charge and discharge cycle is as follows:

[0014] First, perform step constant current charging: The first stage of battery constant current charging: the charging current is I c1 , the charging cut-off voltage is V 1 Or the charging state of charge value is SOC 1 , and then at a voltage of V 1 Or the charging state of charge value is SOC 1 Constant voltage charging to I c2 ; The second stage of constant current charging of the battery: the charging current is I c2 , the charging cut-off voltage is V 2 Or the charging state of charge value is SOC 2 ; Then at voltage V 2 Or the charging state of charge value is SOC 2 Constant voltage charging to I c3 ; This process continues until the nth stage of battery charging, when the charging current is I cn , the charging voltage is V n Or the charging state of charge value is SOC n ; Where: V n Equal to the charging cut-off voltage V max , SOC n Equal to the charge cut-off state of charge SOC max ;

[0015] Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ;

[0016] The step constant current charging and constant current discharging processes are repeated in sequence.

[0017] Furthermore, the pulse charge / constant current discharge cycle comprises the following steps (C1)-(C2):

[0018] (C1) sets a pulse charging current value I pc , a pulse discharge current value I pd , a pulse charging time value t c , a pulse discharge time value t d Or a pulse rest time t r , a charging cut-off voltage V max or a charge cut-off state of charge SOC max ;

[0019] (C2) The specific process of charge and discharge cycle is as follows:

[0020] First, pulse charging: The battery is charged with the first pulse, and the charging current is I pc , the pulse charging time is t c, then the battery is discharged or set to standstill, the discharge current is I pd , the discharge time is t d , the standing time is t r The second and subsequent pulse charging of the battery adopts the same method as the first pulse charging; the pulse charging method is used until the battery voltage reaches the charging cut-off voltage V max Or reach the charging cut-off state of charge SOC max ;

[0021] Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ;

[0022] The pulse charging and constant current discharging process is repeated.

[0023] Furthermore, the small-rate stepwise constant current charge-discharge repair method under periodic normal temperature conditions comprises the following steps (D1)-(D3):

[0024] (D1) Set a set of gradually decreasing constant current charging current values ​​I rc {I rc1 ,I rc2 ,I rc3 ,……,I rcn}, a set of gradually increasing constant current charging voltage values ​​V{V rc1 ,V rc2 ,V rc3 ,.....,V rcn} or a set of gradually increasing constant current charging state of charge values ​​SOC{SOC rc1 ,SOC rc2 ,SOC rc3 ,.....,SOC rcn}, a charging cut-off voltage V rmax or a charge cut-off state of charge SOC rmax , a set of gradually decreasing constant current discharge current values ​​I rd {I rd1 ,I rd2 ,I rd3 ,……,I rdn}, a set of gradually decreasing constant current discharge voltage values ​​V rd {V rd1 ,V rd2 ,V rd3 ,.....,V rdn}, a discharge cut-off voltage V rmin ;

[0025] (D2) The first stage of battery step constant current charging: the charging current is I rc1, charge to constant current charging voltage value V rc1 Or constant current charging state of charge value SOC rc1 , and then at the voltage value V rc1 Or constant current charging state of charge value SOC rc1 When the constant voltage is charged to the current I rc2 ; The second stage of constant current charging of the battery: the charging current is I rc2 , charge to constant current charging voltage value V rc2 Or constant current charging state of charge value SOC rc2 , and then charge at constant voltage to I rc3 , and so on until the battery charging stage n, at which time the charging current is I rcn , charge to constant current charging voltage value V rcn Or constant current charging state of charge value SOC rcn ; Constant current charging voltage value V rcn Equal to the charging cut-off voltage V rmax , constant current charging state of charge value SOC rcn Equal to the charge cut-off state of charge SOC rmax ;

[0026] (D3) Perform step-by-step constant current discharge: The first stage discharge current is I rd1 , discharge to constant current discharge voltage value V rd1 ; The second stage of battery constant current discharge, the discharge current is I rd2 , discharge to constant current discharge voltage value V rd2 ; Continue until the battery discharges to the nth stage, at which point the discharge current is I rdn , discharge to constant current discharge voltage value V rdn ; Constant current discharge voltage value V rdn Equal to the discharge cut-off voltage V rmin ;

[0027] (D4) The battery is cycled 0-2 times in accordance with steps (D2)-(D3) at room temperature.

[0028] Furthermore, during the pulse charge / constant current discharge cycle, in step (C1), the charging time value t c 0.1s~30s; discharge current value I pd 0C~0.2C; discharge time value t d 0.01s~5s; pulse static time value t r 0.01s~30s.

[0029] Furthermore, during the periodic low-rate step constant current charging and discharging process under normal temperature conditions, the step constant current charging current I rc 0.01C~0.5C, step constant current discharge current Ird It is 0.01C~0.5C.

[0030] Furthermore, the working environment temperature range of the battery cycling process is -100°C to 100°C, and the battery repair process is carried out at room temperature.

[0031] The secondary battery using the above-mentioned charge and discharge technology may be a lithium ion battery, a lithium metal battery, a sodium ion battery, a sodium metal battery, a potassium ion battery, a potassium metal battery or a lithium sulfur battery.

[0032] The advantages and benefits of the present invention are as follows:

[0033] The charge and discharge technology of the present invention constructs a stable electrode / electrolyte interface film, reduces side reactions, slows down the degradation of active materials, and improves the cycle performance of the battery under all climate conditions by performing a periodic low-rate charge and discharge repair strategy under normal temperature conditions during the secondary battery cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a technical diagram of the constant current charge and discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions of the present invention.

[0035] Figure 2 This is a technical diagram of the present invention's step constant current charge / constant current discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions.

[0036] Figure 3 This is a technical diagram of the pulse charge / constant current discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions of the present invention.

[0037] Figure 4 It is a 25°C cycle performance curve of the constant current charge and discharge cycle of Example 1 combined with the periodic small-rate step constant current charge and discharge under normal temperature conditions and the comparative example 1.

[0038] Figure 5 The transmission electron microscope images of the negative electrode interface of Example 1 after constant current charge and discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions and comparative example 1 at 25°C for 100 cycles; wherein: (a) comparative example 1; (b) example 1.

[0039] Figure 6 It is a 25°C cycle performance curve of Example 2's step constant current charge / constant current discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions and Comparative Example 2.

[0040] Figure 7It is a transmission electron microscope image of the negative electrode interface of Example 2 after 100 cycles of step constant current charge / constant current discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions and Comparative Example 2 at 25°C; Among them: (a) Comparative Example 2; (b) Example 2.

[0041] Figure 8 It is a 25°C cycle performance curve of the pulse charge / constant current discharge cycle of Example 3 combined with the periodic small-rate step constant current charge and discharge under normal temperature conditions and the comparative example 3.

[0042] Fig. 9 TEM images of the negative electrode interface of Example 3 after 100 cycles of pulse charge / constant current discharge cycle combined with periodic small-rate step constant current charge and discharge under normal temperature conditions and Comparative Example 3 at 25°C; wherein: (a) Comparative Example 3; (b) Example 3. DETAILED DESCRIPTION

[0043] In order to make the technical solution of the present invention better understood, the content of the present invention is further explained below in conjunction with specific implementation examples.

[0044] The formation of an unstable electrode / electrolyte interface during the battery cycle is the main cause of performance degradation, which is particularly evident in batteries that use high-current constant-current charging, step charging, and pulse charging. Therefore, considering the changes in the electrochemical properties of the battery during the cycle, the present invention designs a small-rate step constant-current charge-discharge repair strategy under periodic room temperature conditions during the battery cycle, constructs an electrode / electrolyte interface with excellent comprehensive properties, improves interface stability and interface ion transfer kinetics, and improves the performance of the battery under low-temperature, room-temperature, and high-temperature environments.

[0045] The battery systems used in the following embodiments and comparative examples are consistent, all of which are ternary lithium metal batteries, and the actual capacity of all batteries is within the range of 1.0mAh. The cathode active material is NCM811, the negative electrode is metallic lithium, and it also includes an isolation membrane and an electrolyte. The button battery is obtained through conventional battery assembly, activation and other processes. Among them, in the preparation process of the cathode, NCM811, PVDF and conductive carbon black are first mixed evenly in a mass fraction ratio of 9:0.5:0.5, and prepared with N-methylpyrrolidone as solvent. The isolation membrane is a microporous PP film. The voltage test range of all cycle tests of the present invention is 2.7-4.3V.

[0046] Comparative Example 1

[0047] This comparative example is a constant current charge and discharge cycle, and the test environment temperature is 25°C.

[0048] The constant current charge and discharge cycle process is: the battery is charged with a constant current, and the charging current I c For 1C, the charging cut-off voltage Vmax is 4.3V; then a constant current discharge is performed, and the discharge current I d For 1C, the discharge cut-off voltage V min is 2.7V; and the constant current charging and constant current discharging are repeatedly cycled (one cycle is one cycle, and each cycle first performs a constant current charging and then a constant current discharging).

[0049] Example 1

[0050] This embodiment is a constant current charge and discharge cycle combined with a small rate constant current charge and discharge cycle under periodic room temperature conditions, such as Figure 1 As shown, the constant current charge and discharge repair is performed twice under normal temperature conditions with a small rate step constant current charge and discharge for every 30 cycles, and the test environment temperature is 25°C.

[0051] The constant current charge and discharge cycle process is the same as that of Comparative Example 1.

[0052] The repair process of small-rate step-by-step constant-current charge and discharge at room temperature is as follows:

[0053] The charging process is: charging current I rc1 When the constant current is 0.5C, the charging voltage V rc1 3.7V, 3.7V constant voltage charging to charging current I rc2 When the charging current is 0.2C, the constant current is charged to the voltage V rc2 4.12V, 4.12V constant voltage charging to charging current I rc3 When the current is 0.05C, the constant current is charged to the charging cut-off voltage V max 4.3V;

[0054] The discharge process is as follows: The first stage of constant current discharge of the battery is when the discharge current I rd1 When the voltage is 0.5C, the constant current discharge reaches the voltage value V rd1 is 4.1V; the second stage of battery constant current discharge is when the discharge current I rd2 When the voltage is 0.2C, the constant current discharge is V rd2 is 3.9V; the third stage of constant current discharge of the battery is when the discharge current I rd3 When the voltage is 0.05C, the constant current discharge reaches the voltage value V rd3 is 2.7V.

[0055] The above-mentioned small-rate step constant-current charge-discharge process at room temperature is performed once as one cycle.

[0056] Figure 4 25°C cycle performance curves of Example 1 and Comparative Example 1. It can be seen from the figure that compared with Comparative Example 1, Example 1 has better cycle stability.

[0057] In order to more clearly illustrate the performance advantages of the embodiments, Table 1 briefly summarizes the cycle gram capacity decay rates of Embodiment 1 and Comparative Example 1.

[0058] Table 1

[0059]

[0060] Figure 5 The transmission electron microscope morphology of the negative electrode interface of Example 1 and Comparative Example 1 after 100 cycles at 25°C. The results show that the negative electrode / electrolyte interface film of Example 1 after cycling is thin and uniform, which is conducive to the rapid transmission of ions, which is the key to the battery still having good cycle stability and dynamics. In contrast, the negative electrode / electrolyte interface film of Comparative Example 1 is thick and irregular, and the long ion diffusion path leads to high polarization during battery operation.

[0061] Comparative Example 2

[0062] This comparative example is a step constant current charge / constant current discharge cycle, and the test environment temperature is 25°C.

[0063] The step constant current charging / constant current discharging process is: charging current I c1 2C, constant current charging to V 1 3.7V, 3.7V constant voltage charging to charging current I c2 1C, then charge at 1C constant current to V 2 4.12V, 4.12V constant voltage charging to charging current I c3 The current is 0.6C, and then the constant current is charged at 0.6C to the cut-off voltage V max is 4.3V; then a constant current discharge is performed, and the discharge current I d For 1C, the discharge cut-off voltage V min The step constant current charging and constant current discharging process is repeated in sequence (one cycle is one cycle, and each cycle first performs a constant current charging and then a constant current discharging).

[0064] Example 2

[0065] This embodiment is a step constant current charge / constant current discharge cycle combined with a small rate step constant current charge and discharge under periodic normal temperature conditions, such as Figure 2 As shown, small-rate step constant-current charge and discharge are performed twice at room temperature for every 30 cycles, and the test environment temperature is 25°C.

[0066] The step constant current charge / constant current discharge process is the same as that of comparative example 2.

[0067] The repair process of small-rate step-by-step constant-current charge and discharge at room temperature is as follows:

[0068] The charging process is: charging current Irc1 When the constant current is 0.5C, the charging voltage V rc1 3.7V, 3.7V constant voltage charging to charging current I rc2 When the charging current is 0.2C, the constant current is charged to the voltage V rc2 4.12V, 4.12V constant voltage charging to charging current I rc3 When the current is 0.05C, the constant current is charged to the charging cut-off voltage V max 4.3V;

[0069] The discharge process is as follows: The first stage of constant current discharge of the battery is when the discharge current I rd1 When the voltage is 0.5C, the constant current discharge reaches the voltage value V rd1 is 4.1V; the second stage of battery constant current discharge is when the discharge current I rd2 When the voltage is 0.2C, the constant current discharge is V rd2 is 3.9V; the third stage of constant current discharge of the battery is when the discharge current I rd3 When the voltage is 0.05C, the constant current discharge reaches the voltage value V rd3 is 2.7V.

[0070] The above-mentioned small-rate step constant-current charge-discharge process at room temperature is performed once as one cycle.

[0071] Figure 6 25°C cycle performance curves of Example 2 and Comparative Example 2. As can be seen from the figure, compared with the comparative example, the example of the present invention has better cycle stability.

[0072] In order to more clearly illustrate the performance advantages of the embodiments, Table 2 briefly summarizes the cycle gram capacity decay rates of Example 2 and Comparative Example 2.

[0073] Table 2

[0074]

[0075] Figure 7 The transmission electron microscope morphology of the negative electrode interface of Example 2 and Comparative Example 2 after 100 cycles at 25°C. As shown in the figure, after the cycle of Example 2, the negative electrode still has a thin thickness and a complete interface film. In contrast, Comparative Example 1 forms a thick and irregular negative electrode / electrolyte interface film, which leads to rapid degradation of battery performance.

[0076] Comparative Example 3

[0077] This comparative example is a pulse charge / constant current discharge cycle, and the test environment temperature is 25°C.

[0078] First pulse charging: The battery is charged with the first pulse, and the charging current I pcFor 1C, pulse charging time t c for 1s, and then the battery discharges, the discharge current I pd is 0.02mA, discharge time t d The second and subsequent pulse charging of the battery adopts the same method as the first pulse charging; the pulse charging method is used until the battery voltage reaches 4.3V;

[0079] Then a constant current discharge is performed, and the discharge current I d 1C, discharge to voltage 2.7V;

[0080] The above pulse charging and constant current discharging process is repeated (one cycle is one period, and each period first performs a constant current charging and then a constant current discharging).

[0081] Example 3

[0082] This embodiment 3 is a pulse charge / constant current discharge cycle combined with periodic small rate step constant current charge and discharge under normal temperature conditions, such as Figure 3 As shown, small-rate step constant-current charge and discharge are performed twice at room temperature for every 30 cycles, and the test environment temperature is 25°C.

[0083] The process of pulse charging / constant current discharging is the same as that of comparative example 3.

[0084] The repair process of small-rate step-by-step constant-current charge and discharge at room temperature is as follows:

[0085] The charging process is: charging current I rc1 When the constant current is 0.5C, the charging voltage V rc1 3.7V, 3.7V constant voltage charging to charging current I rc2 When the charging current is 0.2C, the constant current is charged to the voltage V rc2 4.12V, 4.12V constant voltage charging to charging current I rc3 When the current is 0.05C, the constant current is charged to the charging cut-off voltage V max 4.3V;

[0086] The discharge process is as follows: The first stage of constant current discharge of the battery is when the discharge current I rd1 When the voltage is 0.5C, the constant current discharge reaches the voltage value V rd1 is 4.1V; the second stage of battery constant current discharge is when the discharge current I rd2 When the voltage is 0.2C, the constant current discharge is V rd2 is 3.9V; the third stage of constant current discharge of the battery is when the discharge current I rd3 When the voltage is 0.05C, the constant current discharge reaches the voltage value V rd3 is 2.7V.

[0087] The above-mentioned small-rate step constant-current charge-discharge process at room temperature is performed once as one cycle.

[0088] Figure 8 They are 25°C cycle performance curves of Example 3 and Comparative Example 3. As can be seen from the figure, compared with the comparative example, the example of the present invention has better cycle stability.

[0089] In order to more clearly illustrate the performance advantages of the embodiments, Table 3 briefly summarizes the cycle gram capacity decay rates of Embodiment 3 and Comparative Example 3.

[0090] Table 3

[0091]

[0092] Fig. 9 The transmission electron microscope morphology of the negative electrode interface of Example 3 and Comparative Example 3 after 100 cycles at 25°C. As shown in the figure, compared with the thick negative electrode / electrolyte interface film formed in Comparative Example 3, the negative electrode interface film after the cycle of Example 3 is thin and uniform. The negative electrode / electrolyte interface film with excellent comprehensive properties significantly improves the battery performance.

[0093] In combination with the embodiments described above, compared with batteries that do not undergo periodic small-rate step constant-current charge and discharge under normal temperature conditions during the cycle process, the charge and discharge optimization technology of the present invention exhibits excellent electrochemical performance and has good engineering application feasibility.

[0094] Finally, it should be noted that the embodiments described above are only used to describe the technical solutions of the present invention, rather than to limit them. The present invention can also make appropriate modifications to the above-mentioned embodiments, or replace some or all of the technical features therein with equivalents. Therefore, some modifications or changes to the present invention should also fall within the scope of protection of the claims of the present invention.

Claims

1. A charging and discharging technology based on a normal temperature small rate step constant current charging and discharging repair method, Features: This technology uses a small-rate step constant current charge and discharge repair method under periodic normal temperature conditions during the battery cycle process to improve battery cycle stability and extend battery cycle life.

2. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 1, Features: The battery cycle process includes three types: constant current charge and discharge cycle, step constant current charge / constant current discharge cycle and pulse charge / constant current discharge cycle.

3. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 2, Features: The constant current charge-discharge cycle method comprises the following steps (A1)-(A2): (A1) Set the constant charging current I c , a constant discharge current I d , a charging cut-off voltage V max or a charge cut-off state of charge SOC max , a discharge cut-off voltage V min ; (A2) The specific process of the constant current charge and discharge cycle is: the battery is charged at a constant current, and the charging current is I c , the charging cut-off voltage is V max Or the charging end state of charge is SOC max ; Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ; Repeat the constant current charging and constant current discharging cycles.

4. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 2, Features: The step constant current charge / constant current discharge cycle method comprises the following steps (B1)-(B2): (B1) Set a set of gradually decreasing constant current charging current values ​​I c {I c1 ,I c2 ,I c3 ,……,I cn }, a set of gradually increasing constant current charging voltage values ​​V{V 1 ,V 2 ,V 3 ,.....,V n } or a set of gradually increasing constant current charging state of charge values ​​SOC{SOC 1 ,SOC 2 ,SOC 3 ,.....,SOC n }, a charging cut-off voltage V max or a charge cut-off state of charge SOC max , a discharge cut-off voltage V min ; (B2) The specific process of charge and discharge cycle is as follows: First, perform step constant current charging: The first stage of battery constant current charging: the charging current is I c1 , the charging cut-off voltage is V 1 Or the charging state of charge value is SOC 1 , and then at a voltage of V 1 Or the charging state of charge value is SOC 1 Constant voltage charging to I c2 ; The second stage of constant current charging of the battery: the charging current is I c2 , the charging cut-off voltage is V 2 Or the charging state of charge value is SOC 2 ; Then at voltage V 2 Or the charging state of charge value is SOC 2 Constant voltage charging to I c3 ; This process continues until the nth stage of battery charging, when the charging current is I cn , the charging voltage is V n Or the charging state of charge value is SOC n ; Where: V n Equal to the charging cut-off voltage V max , SOC n Equal to the charge cut-off state of charge SOC max ; Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ; The step constant current charging and constant current discharging processes are repeated in sequence.

5. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 2, Features: The pulse charge / constant current discharge cycle comprises the following steps (C1)-(C2): (C1) sets a pulse charging current value I pc , a pulse discharge current value I pd , a pulse charging time value t c , a pulse discharge time value t d Or a pulse rest time t r , a charging cut-off voltage V max or a charge cut-off state of charge SOC max ; (C2) The specific process of charge and discharge cycle is as follows: First, pulse charging: The battery is charged with the first pulse, and the charging current is I pc , the pulse charging time is t c , then the battery is discharged or set to standstill, the discharge current is I pd , the discharge time is t d , the standing time is t r The second and subsequent pulse charging of the battery adopts the same method as the first pulse charging; the pulse charging method is used until the battery voltage reaches the charging cut-off voltage V max Or reach the charging cut-off state of charge SOC max ; Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ; The pulse charging and constant current discharging process is repeated.

6. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 2, Features: The small-rate step-constant-current charge-discharge repair method under periodic normal temperature conditions comprises the following steps (D1)-(D3): (D1) Set a set of gradually decreasing constant current charging current values ​​I rc {I rc1 ,I rc2 ,I rc3 ,……,I rcn }, a set of gradually increasing constant current charging voltage values ​​V{V rc1 ,V rc2 ,V rc3 ,.....,V rcn } or a set of gradually increasing constant current charging state of charge values ​​SOC{SOC rc1 ,SOC rc2 ,SOC rc3 ,.....,SOC rcn }, a charging cut-off voltage V rmax or a charge cut-off state of charge SOC rmax , a set of gradually decreasing constant current discharge current values ​​I rd {I rd1 ,I rd2 ,I rd3 ,……,I rdn }, a set of gradually decreasing constant current discharge voltage values ​​V rd {V rd1 ,V rd2 ,V rd3 ,.....,V rdn }, a discharge cut-off voltage V rmin ; (D2) The first stage of battery step constant current charging: the charging current is I rc1 , charge to constant current charging voltage value V rc1 Or constant current charging state of charge value SOC rc1 , and then charge at constant voltage to I rc2 ; The second stage of constant current charging of the battery: the charging current is I rc2 , charge to constant current charging voltage value V rc2 Or constant current charging state of charge value SOC rc2 , and then charge at constant voltage to I rc3 , and so on until the battery charging stage n, at which time the charging current is I rcn , charge to constant current charging voltage value V rcn Or constant current charging state of charge value SOC rcn ; Constant current charging voltage value V rcn Equal to the charging cut-off voltage V rmax , constant current charging state of charge value SOC rcn Equal to the charge cut-off state of charge SOC rmax ; (D3) performs step-by-step constant current discharge: the first stage discharge current is I rd1 , discharge to constant current discharge voltage value V rd1 ; The second stage of battery constant current discharge, the discharge current is I rd2 , discharge to constant current discharge voltage value V rd2 ; This process is continued until the battery discharges to the nth stage, at which point the discharge current is I rdn , discharge to constant current discharge voltage value V rdn ; Constant current discharge voltage value V rdn Equal to the discharge cut-off voltage V rmin ; (D4) The battery is cycled 0-2 times in accordance with steps (D2)-(D3) at room temperature.

7. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 5, Features: During the pulse charge / constant current discharge cycle, in step (C1), the charging time value t c 0.1s~30s; discharge current value I pd 0C~0.2C; discharge time value t d 0.01s~5s; pulse static time value t r 0.01s~30s.

8. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to claim 6, Features: During the small-rate step constant current charge-discharge repair process under the periodic normal temperature condition, the step constant current charge current I rc 0.01C~0.5C, step constant current discharge current I rd It is 0.01C~0.5C.

9. The charging and discharging technology based on the normal temperature small rate step constant current charging and discharging repair method according to any one of claims 1 to 8, Features: The working environment temperature range of the battery cycling process is -100℃~100℃, and the battery repair process is carried out at room temperature.

10. A secondary battery using the charge-discharge technology based on the normal temperature small rate step constant current charge-discharge repair method as described in any one of claims 1 to 8, Features: The secondary battery is a lithium ion battery, a lithium metal battery, a sodium ion battery, a sodium metal battery, a potassium ion battery, a potassium metal battery or a lithium sulfur battery.

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