Wide-temperature-range charging and discharging method based on secondary battery

Abstract

The invention belongs to the technical field of battery charging and discharging, and particularly relates to a wide-temperature-range charging and discharging method based on a secondary battery. The secondary battery is subjected to low-rate constant-current charging and discharging under a periodic normal-temperature condition in a wide-temperature-range circulating process, an electrode / electrolyte interfacial film with excellent properties can be formed by the method, the generation of low-temperature lithium dendrites is inhibited, and the cycle life of the battery at high temperature and low temperature can be effectively prolonged. Compared with a common charge-discharge technology, the charge-discharge technology can significantly prolong the wide-temperature cycle performance of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery charging and discharging, and specifically relates to a wide temperature range charging and discharging method based on a secondary battery. Background Art

[0002] In recent years, advanced energy storage technologies represented by lithium-ion batteries have been widely used in consumer electronics, electric vehicles, and energy conversion, which has promoted energy transformation and the development of intelligent electrification. However, the development of electrochemical energy storage devices is still limited by the problems of energy density far lower than gasoline / diesel, less than ideal endurance, shorter cycle performance, and poor adaptability to climate and environment.

[0003] Among them, an excellent electrode / electrolyte interface is crucial for the reliable operation of the battery in high or low temperature environments. The main methods for constructing a stable electrode / electrolyte interface include electrode design, artificial electrode interface membrane and electrolyte regulation. These strategies have improved the electrode interface properties and enhanced battery performance. In addition, improvements in charging and discharging technology can also effectively improve battery performance, mainly reflected in the ability to achieve a stable and reliable electrode interface membrane.

[0004] There have been many research reports on the charging and discharging technology based on secondary batteries. The charging and discharging technologies that have been applied in engineering mainly include constant current charging and discharging, step constant current charging and pulse charging. Constant current charging and discharging technology is simple, easy to implement, and is the most widely used. Step constant current charging technology uses the changes in battery characteristics during the charging process to tap the charging potential without affecting other performance. It has been promoted in engineering. Pulse charging technology can minimize the polarization of the charging process and has also been used in kinetic energy recovery of electric vehicles. Although the above-mentioned charging and discharging technologies have a positive effect on improving battery cycle performance, shortening charging time or reducing energy consumption, they ignore the trend of electrode / electrolyte interface film degradation during the battery life, especially in high or low temperature environments, and cannot be dynamically or timely optimized according to changes in electrochemical properties.

[0005] Therefore, developing new charging and discharging technologies, achieving timely optimization of the battery life, reducing side reactions, building a stable electrode / electrolyte interface film, and improving the cycle performance under all-climate conditions are of great significance to promoting the application of secondary batteries. Summary of the invention

[0006] The purpose of the present invention is to provide a wide temperature range charging and discharging method based on secondary batteries. By periodically charging and discharging the battery at a small rate and constant current under normal temperature conditions, a stable electrode / electrolyte interface is constructed to slow down performance degradation, especially for batteries in high or low temperature environments, thereby extending the cycle life under all climate conditions.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A wide temperature range charging and discharging method based on a secondary battery, wherein the secondary battery is periodically charged and discharged at a small rate constant current under normal temperature conditions during a wide temperature range cycle process.

[0009] The wide temperature range charging and discharging method based on a secondary battery, the secondary battery cycle process includes a constant current charging and discharging cycle, a step constant current charging / constant current discharging cycle or a pulse charging / constant current charging cycle.

[0010] The wide temperature range charging and discharging method based on the secondary battery, the constant current charging and discharging cycle, comprises the following steps (A1)-(A2):

[0011] (A1) Set a 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 ;

[0012] (A2) The specific process of the constant current charge and discharge cycle is: the secondary battery is charged at a constant current under low temperature, normal temperature or high temperature environment, and the constant charging current is I c , the charging cut-off voltage is V max Or the charging end state of charge is SOC max , and then a constant current discharge is performed, the constant discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above constant current charging and constant current discharging cycles.

[0013] The wide temperature range charging and discharging method based on the secondary battery, the step constant current charging / constant current discharging cycle, comprises the following steps (B1)-(B2):

[0014] (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 maxor a charge cut-off state of charge SOC max , a discharge cut-off voltage V min ;

[0015] (B2) The first stage of constant current charging of the secondary battery, the constant current charging current value is I c1 , the constant current charging voltage value is V 1 Or constant current charging state of charge value SOC 1 ; The second stage of constant current charging of secondary batteries, the constant current charging current value is I c2 , the constant current charging voltage value is V 2 Or constant current charging state of charge value SOC 2 ; proceed in sequence until the secondary battery is charged to the nth stage, and the constant current charging current value is I cn , the constant current charging voltage value is V n Or constant current charging state of charge value SOC n ; This cycle continues until the secondary battery voltage reaches the charging cut-off voltage V max Or charge cut-off state of charge SOC max , and then a constant current discharge is performed, the discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above-mentioned step constant current charging and constant current discharging cycles.

[0016] The wide temperature range charging and discharging method based on a secondary battery, a pulse charging / constant current discharging cycle, comprises the following steps (C1)-(C2):

[0017] (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 value t r , a cut-off voltage V max or a cut-off state of charge SOC max ;

[0018] (C2) The first pulse charging of the secondary battery, the pulse charging current value is I pc , the pulse charging time value is t c , then the secondary battery is discharged or set to standstill, the pulse discharge current value is I pd , the pulse discharge time value is t d Or the pulse rest time value is t r The second and subsequent pulse charging of the secondary battery adopts the same method as the first pulse charging; this cycle continues until the secondary battery voltage reaches the cut-off voltage V max Or cut-off state of charge SOCmax ; Then a constant current discharge is performed, and the discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above-mentioned pulse charging and constant current discharging cycles.

[0019] In the wide temperature range charging and discharging method based on a secondary battery, in the step (C1) of the pulse charging stage, the pulse charging time value t c In the range of 0.1s to 30s, the pulse discharge current value I pd In the range of 0C~0.2C, the pulse discharge time value t d In the range of 0.01s to 5s, the pulse static time value t r In the range of 0.01s to 30s.

[0020] The wide temperature range charging and discharging method based on the secondary battery comprises the following steps (D1)-(D3):

[0021] (D1) Set a constant charging current I under normal temperature conditions rc , a constant discharge current I rd , a charging cut-off voltage V max , a discharge cut-off voltage V min ;

[0022] (D2) After the secondary battery has been cycled a certain number of times at low temperature, room temperature or high temperature, the secondary battery is placed at room temperature for one or two constant current charge and discharge cycles, with the constant charge current being I rc , the charging cut-off voltage is V max , the constant discharge current is I rd , the discharge cut-off voltage is V min ; After completing constant current charging and discharging at room temperature, the secondary battery is placed in a low temperature, room temperature or high temperature environment for circulation again;

[0023] (D3) The secondary battery periodically repeats step (D2) during the cycle process under low temperature, normal temperature or high temperature environment.

[0024] The wide temperature range charging and discharging method based on the secondary battery, the small rate constant current charging and discharging cycle under the periodic normal temperature condition, the constant charging current I rc In the range of 0.01C~0.2C, the constant discharge current I rd In the range of 0.01C~0.2C.

[0025] The wide temperature range charging and discharging method based on the secondary battery is that the working environment temperature range of the secondary battery is -100°C to 100°C.

[0026] The wide temperature range charging and discharging method based on a secondary battery, the secondary battery includes 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.

[0027] The design concept of the present invention is:

[0028] The present invention forms an electrode / electrolyte interface film with excellent properties by optimizing the charge and discharge technology during the life of the secondary battery, thereby inhibiting the generation of low-temperature lithium dendrites and effectively improving the cycle life of the battery at high and low temperatures.

[0029] The advantages and benefits of the present invention are as follows:

[0030] The charge and discharge technology of the present invention builds a stable electrode / electrolyte interface film, reduces side reactions, and improves the battery's cycle performance under all climate conditions by periodically charging and discharging at a low rate under normal temperature during the life of the secondary battery. Compared with ordinary charge and discharge technologies, this charge and discharge technology can significantly extend the battery's wide temperature cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a technical diagram of constant current charge and discharge cycle combined with periodic small-rate constant current charge and discharge under normal temperature conditions.

[0032] Figure 2 This is a technical diagram of a step constant current charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions.

[0033] Figure 3 This is a technical diagram of a pulse charge / constant current discharge cycle combined with periodic low-rate constant current charge and discharge under normal temperature conditions.

[0034] Figure 4 It is a cycle performance curve of Example 1 constant current charge and discharge cycle combined with small rate constant current charge and discharge under periodic room temperature conditions and comparative example 1 at 25°C.

[0035] Figure 5 It is a graph showing the cycle performance of Example 2 constant current charge and discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions and Comparative Example 2 at -20°C.

[0036] Figure 6 It is a graph showing the cycle performance of Example 3 under constant current charge and discharge conditions combined with periodic small rate constant current charge and discharge under normal temperature conditions and Comparative Example 3 at 50°C.

[0037] Figure 7 It is a cycle performance curve of Example 4 at 25°C combined with the step constant current charge / constant current discharge cycle under periodic normal temperature conditions and the comparative example 4.

[0038] Figure 8 It is a cycle performance curve diagram of Example 5 step constant current charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions and comparative example 5 at -20°C.

[0039] Fig. 9 It is a cycle performance curve of Example 6 step constant current charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions and comparative example 6 at 50°C.

[0040] Fig.10 It is a cycle performance curve of Example 7 pulse charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions and Comparative Example 7 at 25°C.

[0041] Fig.11 It is a cycle performance curve diagram of Example 8 pulse charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions and Comparative Example 8 at -20°C.

[0042] Fig.12 It is a cycle performance curve of Example 9 pulse charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions and Comparative Example 9 at 50°C. DETAILED DESCRIPTION

[0043] In the specific implementation process, the present invention proposes a wide temperature range charging and discharging method based on a secondary battery. The secondary battery performs periodic small-rate constant current charging and discharging under normal temperature conditions during the wide temperature range cycle process. The secondary battery cycle process includes three types: constant current charging and discharging cycle, step constant current charging / constant current discharging cycle, and pulse charging / constant current charging cycle.

[0044] like Figure 1 As shown, the constant current charge and discharge cycle includes the following steps (A1)-(A2):

[0045] (A1) Set a 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 ; Among them, the constant charging current I c In the range of 0.01C~100C, the constant discharge current I d In the range of 0.01C~100C;

[0046] (A2) The specific process of the constant current charge and discharge cycle is: the secondary battery is charged at a constant current in a low temperature (-100 to 0°C), normal temperature or high temperature (35 to 100°C) environment, and the constant charging current is I c, the charging cut-off voltage is V max Or the charging end state of charge is SOC max , and then a constant current discharge is performed, the constant discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above constant current charging and constant current discharging cycles.

[0047] like Figure 2 As shown, the step constant current charge / constant current discharge cycle includes the following steps (B1)-(B2):

[0048] (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 ; Among them, the constant current charging current value I c In the range of 0.01C to 100C, the constant current charging state of charge value SOC is in the range of 0 to 100%;

[0049] (B2) The first stage of constant current charging of the secondary battery, the constant current charging current value is I c1 , the constant current charging voltage value is V 1 Or constant current charging state of charge value SOC 1 ; The second stage of constant current charging of secondary batteries, the constant current charging current value is I c2 , the constant current charging voltage value is V 2 Or constant current charging state of charge value SOC 2 ; proceed in sequence until the secondary battery is charged to the nth stage, and the constant current charging current value is I cn , the constant current charging voltage value is V n Or constant current charging state of charge value SOC n ; This cycle continues until the secondary battery voltage reaches the charging cut-off voltage V max Or charge cut-off state of charge SOC max, and then a constant current discharge is performed, the discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above-mentioned step constant current charging and constant current discharging cycles.

[0050] like Figure 3 As shown, the pulse charge / constant current discharge cycle includes the following steps (C1)-(C2):

[0051] (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 value t r , a cut-off voltage V max or a cut-off state of charge SOC max ;

[0052] (C2) The first pulse charging of the secondary battery, the pulse charging current value is I pc , the pulse charging time value is t c , then the secondary battery is discharged or set to standstill, the pulse discharge current value is I pd , the pulse discharge time value is t d Or the pulse rest time value is t r The second and subsequent pulse charging of the secondary battery adopts the same method as the first pulse charging; this cycle continues until the secondary battery voltage reaches the cut-off voltage V max Or 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 ; Repeat the above-mentioned pulse charging and constant current discharging cycles.

[0053] like Figure 1 As shown, the present invention adopts a small rate constant current charge and discharge cycle under periodic room temperature conditions, including the following steps (D1)-(D3):

[0054] (D1) Set a constant charging current I under normal temperature conditions rc , a constant discharge current I rd , a charging cut-off voltage V max , a discharge cut-off voltage V min ;

[0055] (D2) After the secondary battery has been cycled a certain number of times at low temperature (-100 to 0°C), room temperature or high temperature (35 to 100°C), the secondary battery is placed at room temperature for one or two constant current charge and discharge cycles, with the constant charge current being I rc , the charging cut-off voltage is V max , the constant discharge current is I rd , the discharge cut-off voltage is V min ; After completing constant current charging and discharging at room temperature, the secondary battery is placed in a low temperature, room temperature or high temperature environment for circulation again;

[0056] (D3) The secondary battery periodically repeats step (D2) during the cycle process under low temperature, normal temperature or high temperature environment.

[0057] In order to make the technical solution of the present invention better understood, the content of the present invention is further described below in conjunction with specific embodiments and comparative examples.

[0058] The battery systems used in all embodiments and comparative examples of the present invention 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 mass ratio of the three elements of nickel, cobalt and manganese: 80% nickel, 10% cobalt and 10% manganese), the negative electrode is metallic lithium, and also includes an isolation membrane and an electrolyte. The button battery is obtained by battery assembly, activation and other processes. Among them, in the preparation process of the cathode, NCM811, polyvinylidene fluoride (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 the solvent. The isolation membrane is a microporous PP film. The voltage test range of all cycle tests of the present invention is 2.8~4.3V.

[0059] Comparative Example 1

[0060] Comparative Example 1 of the present invention is a constant current charge and discharge cycle, and the test environment temperature is 25°C.

[0061] Example 1

[0062] Embodiment 1 of the present invention is a constant current charge and discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions. Small rate constant current charge and discharge under normal temperature conditions are performed twice for every 30 cycles, and the test environment temperature is 25°C.

[0063] Comparative Example 2

[0064] Comparative Example 2 of the present invention is a constant current charge and discharge cycle, and the test environment temperature is -20°C.

[0065] Example 2

[0066] Embodiment 2 of the present invention is a constant current charge and discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions. Small rate constant current charge and discharge under normal temperature conditions are performed twice for every 20 cycles, and the test environment temperature is -20°C.

[0067] Comparative Example 3

[0068] Comparative Example 3 of the present invention is a constant current charge and discharge cycle, and the test environment temperature is 50°C.

[0069] Example 3

[0070] Embodiment 3 of the present invention is a constant current charge and discharge cycle combined with periodic small-rate constant current charge and discharge under normal temperature conditions. Small-rate constant current charge and discharge under normal temperature conditions are performed once every 10 cycles, and the test environment temperature is 50°C.

[0071] like Figures 4 to 6 As shown, the 25°C cycle performance curve of Example 1 and Comparative Example 1, the -20°C cycle performance curve of Example 2 and Comparative Example 2, and the 50°C cycle performance curve of Example 3 and Comparative Example 3, and the current size of the 25°C cycle and the 50°C cycle is 1C, the current size of the -20°C cycle is 0.5C, and the current size of the room temperature small rate constant current charge and discharge is 0.1C. It can be seen from the figure that compared with the comparative example, all embodiments of the present invention have better cycle stability.

[0072] In order to more clearly illustrate the performance advantages of the embodiments, Table 1 briefly summarizes the cycle gram capacity decay rates of Examples 1 to 3 and Comparative Examples 1 to 3.

[0073] Table 1

[0074]

[0075] Comparative Example 4

[0076] Comparative Example 4 of the present invention is a step constant current charge / constant current discharge cycle, and the test environment temperature is 25°C.

[0077] Example 4

[0078] Embodiment 4 of the present invention is a step constant current charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions, and the test environment temperature is 25°C.

[0079] Comparative Example 5

[0080] Comparative Example 5 of the present invention is a step constant current charge / constant current discharge cycle, and the test environment temperature is -20°C.

[0081] Example 5

[0082] Embodiment 5 of the present invention is a step constant current charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions, and the test environment temperature is -20°C.

[0083] Comparative Example 6

[0084] Comparative Example 6 of the present invention is a step constant current charge / constant current discharge cycle, and the test environment temperature is 50°C.

[0085] Example 6

[0086] Embodiment 6 of the present invention is a step constant current charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions, and the test environment temperature is 50°C.

[0087] like Figures 7 to 9 As shown, the 25°C cycle performance curve of Example 4 and Comparative Example 4, the -20°C cycle performance curve of Example 5 and Comparative Example 5, and the 50°C cycle performance curve of Example 6 and Comparative Example 6, and the charging process of 25°C cycle and 50°C cycle are: 2C constant current charging to 3.7V, 3.7V constant voltage charging to 1C, 1C constant current charging to 4.12V, 4.12V constant voltage charging to 0.6C, 0.6C constant current charging to 4.3V, the discharge current is 1C, and the charging process of -20°C cycle is: 1C constant current charging to 3.7V, 3.7V constant voltage charging to 0.5C, 1C constant current charging to 4.12V, 4.12V constant voltage charging to 0.3C, 0.3C constant current charging to 4.3V, and the discharge current is 0.5C. It can be seen from the figure that compared with the comparative example, all embodiments of the present invention have better cycle stability.

[0088] In order to more clearly illustrate the performance advantages of the embodiments, Table 2 briefly summarizes the cycle gram capacity decay rates of Examples 4 to 6 and Comparative Examples 4 to 6.

[0089] Table 2

[0090]

[0091] Comparative Example 7

[0092] Comparative Example 7 of the present invention is a pulse charge / constant current discharge cycle, and the test environment temperature is 25°C.

[0093] Example 7

[0094] Example 7 of the present invention is a pulse charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions, and the test environment temperature is 25°C.

[0095] Comparative Example 8

[0096] Comparative Example 8 of the present invention is a pulse charge / constant current discharge cycle, and the test environment temperature is -20°C.

[0097] Example 8

[0098] Embodiment 8 of the present invention is a pulse charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions, and the test environment temperature is -20°C.

[0099] Comparative Example 9

[0100] Comparative Example 9 of the present invention is a pulse charge / constant current discharge cycle, and the test environment temperature is 50°C.

[0101] Example 9

[0102] Embodiment 9 of the present invention is a pulse charge / constant current discharge cycle combined with periodic small rate constant current charge and discharge under normal temperature conditions, and the test environment temperature is 50°C.

[0103] like Figures 10 to 12 As shown, the 25°C cycle performance curve of Example 7 and Comparative Example 7, the -20°C cycle performance curve of Example 8 and Comparative Example 8, and the 50°C cycle performance curve of Example 9 and Comparative Example 9, and the pulse charging current size of the 25°C cycle and the 50°C cycle is 1C, the pulse charging time is 1s, the pulse discharge current size is 0.02mA, the pulse discharge time is 0.1s, and the constant current discharge current size is 1C, the pulse charging current size of the -20°C cycle is 0.5C, the pulse charging time is 1s, the pulse discharge current size is 0.01mA, the pulse discharge time is 0.1s, and the constant current discharge current size is 0.5C. It can be seen from the figure that compared with the comparative example, all embodiments of the present invention have better cycle stability.

[0104] In order to more clearly illustrate the performance advantages of the embodiments, Table 3 briefly summarizes the cycle gram capacity decay rates of Examples 7 to 9 and Comparative Examples 7 to 9.

[0105] Table 3

[0106]

[0107] In combination with the embodiments described above, compared with batteries that do not undergo periodic small-rate constant-current charge and discharge under normal temperature conditions during the cycle process, the wide temperature range charge and discharge technology of the present invention not only has significantly better performance advantages under normal temperature conditions, but also exhibits excellent electrochemical properties in high and low temperature environments, and has good engineering application potential.

[0108] 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 wide temperature range charging and discharging method based on a secondary battery, characterized in that: The secondary battery is cycled over a wide temperature range and is periodically charged and discharged at a low rate and constant current under normal temperature conditions.

2. The wide temperature range charging and discharging method based on a secondary battery according to claim 1, characterized in that: The secondary battery cycle process includes constant current charge and discharge cycles, step constant current charge / constant current discharge cycles or pulse charge / constant current charge cycles.

3. The wide temperature range charging and discharging method based on a secondary battery according to claim 2, characterized in that: The constant current charge and discharge cycle includes the following steps (A1)-(A2): (A1) Set a 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 secondary battery is charged at a constant current under low temperature, normal temperature or high temperature environment, and the constant charging current is I c , the charging cut-off voltage is V max Or the charging end state of charge is SOC max , and then a constant current discharge is performed, the constant discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above constant current charging and constant current discharging cycles.

4. The wide temperature range charging and discharging method based on a secondary battery according to claim 2, characterized in that: The step constant current charge / constant current discharge cycle includes 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{V1, V2, V3, ....., V n } or a set of gradually increasing constant current charging state of charge values ​​SOC {SOC1, SOC2, SOC3,....., 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 first stage of constant current charging of the secondary battery, the constant current charging current value is I c1 , the constant current charging voltage value is V1 or the constant current charging state of charge value is SOC1; in the second stage of constant current charging of the secondary battery, the constant current charging current value is I c2 , the constant current charging voltage value is V2 or the constant current charging state of charge value is SOC2; proceed in sequence until the secondary battery is charged to the nth stage, the constant current charging current value is I cn , the constant current charging voltage value is V n Or constant current charging state of charge value SOC n ; This cycle continues until the secondary battery voltage reaches the charging cut-off voltage V max Or charge cut-off state of charge SOC max , and then a constant current discharge is performed, the discharge current is I d , the discharge cut-off voltage is V min ; Repeat the above-mentioned step constant current charging and constant current discharging cycles.

5. The wide temperature range charging and discharging method based on a secondary battery according to claim 2, characterized in that: The pulse charge / constant current discharge cycle includes 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 value t r , a cut-off voltage V max or a cut-off state of charge SOC max ; (C2) The first pulse charging of the secondary battery, the pulse charging current value is I pc , the pulse charging time value is t c , then the secondary battery is discharged or set to standstill, the pulse discharge current value is I pd , the pulse discharge time value is t d Or the pulse rest time value is t r The second and subsequent pulse charging of the secondary battery adopts the same method as the first pulse charging; this cycle continues until the secondary battery voltage reaches the cut-off voltage V max Or 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 ; Repeat the above-mentioned pulse charging and constant current discharging cycles.

6. The wide temperature range charging and discharging method based on a secondary battery according to claim 5, characterized in that: In the step (C1) of the pulse charging phase, the pulse charging time value t c In the range of 0.1s to 30s, the pulse discharge current value I pd In the range of 0C~0.2C, the pulse discharge time value t d In the range of 0.01s to 5s, the pulse static time value t r In the range of 0.01s to 30s.

7. The wide temperature range charging and discharging method based on a secondary battery according to claim 1, characterized in that: The low rate constant current charge and discharge cycle under periodic room temperature conditions includes the following steps (D1)-(D3): (D1) Set a constant charging current I under normal temperature conditions rc , a constant discharge current I rd , a charging cut-off voltage V max , a discharge cut-off voltage V min ; (D2) After the secondary battery has been cycled a certain number of times at low temperature, normal temperature or high temperature, the secondary battery is placed at normal temperature for one or two constant current charge and discharge cycles, with the constant charge current being I rc , the charging cut-off voltage is V max , the constant discharge current is I rd , the discharge cut-off voltage is V min ; After completing constant current charging and discharging at room temperature, the secondary battery is placed in a low temperature, room temperature or high temperature environment for circulation again; (D3) The secondary battery periodically repeats step (D2) during the cycle process under low temperature, normal temperature or high temperature environment.

8. The wide temperature range charging and discharging method based on a secondary battery according to claim 7, characterized in that: Small rate constant current charge and discharge cycle under periodic room temperature conditions, constant charging current I rc In the range of 0.01C~0.2C, the constant discharge current I rd In the range of 0.01C~0.2C.

9. The wide temperature range charging and discharging method based on a secondary battery according to any one of claims 1 to 8, characterized in that: The working environment temperature range of the secondary battery is -100℃~100℃.

10. The wide temperature range charging and discharging method based on a secondary battery according to claim 1, characterized in that: The secondary battery includes 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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