Self-preheating method for a lithium-ion battery

Abstract

The present invention discloses a self-preheating method for a lithium-ion battery. When the battery is at -20°C to -30°C, it is electrically connected to the battery to be preheated through an external power supply for multiple heating-eliminating concentration polarization cycles. Each heating-eliminating concentration polarization cycle includes a rapid charge and discharge for heating and a rapid charge and discharge for eliminating concentration polarization. The rapid charge and discharge for heating and the rapid charge and discharge for eliminating concentration polarization respectively include a charging stage, a rest stage, and a discharging stage. The charging rate in the charging stage is C charge , and the charging time is T charge ; the rest time in the rest stage is T rest ; the discharging rate in the discharging stage is C discharge , and the discharging time is T discharge ; after the battery temperature is increased through multiple heating-eliminating concentration polarization cycles, the battery is charged and discharged normally; the present invention preheats and activates the battery from the inside of the battery, and inhibits the formation of lithium dendrites during normal rate charging and discharging of the battery in a low-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery heating, and particularly to a self-preheating method for a lithium-ion battery. Background Art

[0002] At low temperatures, the kinetic performance of the electrolyte and the positive and negative electrodes decreases, especially the large internal resistance of the battery caused by the increased viscosity of the electrolyte. Charging and discharging the battery directly at normal working current at low temperatures will cause concentration polarization, induce the deposition of lithium to form lithium dendrites, and in severe cases, even penetrate the diaphragm, causing internal short circuit and leading to explosion.

[0003] Currently, the heating methods for batteries are mostly external heating, mainly achieved through heat conduction and heat convection. However, no matter what kind of external heating method is used, it is necessary to provide external energy, and there will be a certain heat loss in the transfer of the external heat source in a low-temperature environment; the heat transfer will also be uneven due to distance and contact area, and the reliability and uniformity of heating the battery from the outside need to be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a self-preheating method for a lithium-ion battery. The present invention controls the charging and discharging of the battery to gradually preheat and activate the battery from the inside of the battery, and inhibits the formation of lithium dendrites during normal-rate charging and discharging of the battery in a low-temperature environment.

[0005] To solve this technical problem, the technical solution of the present invention is: a self-preheating method for a lithium-ion battery. When the battery is at -20°C to -30°C, it is electrically connected to the battery to be preheated through an external power supply for multiple heating - concentration polarization elimination cycles. Each heating - concentration polarization elimination cycle includes a heating rapid charge and discharge and a concentration polarization elimination rapid charge and discharge;

[0006] Among them, the rapid charge and discharge for heating rapid charge and discharge or concentration polarization elimination includes a charging stage, a rest stage, and a discharging stage;

[0007] The charging rate in the charging stage is C charge , and the charging time is T charge ;

[0008] The rest time in the rest stage is T rest ;

[0009] The discharging rate in the discharging stage is C discharge , and the discharging time is T discharge ;

[0010] After the battery temperature is increased through multiple heating - concentration polarization elimination cycles, the battery is charged and discharged normally.

[0011] Preferably, it is the same heating - concentration polarization elimination cycle;

[0012] Rapid charge and discharge process with temperature rise:

[0013] The charging rate during the charging stage is C1 charge , and the charging time is T1 charge ;

[0014] The rest time during the rest stage is T1 rest ;

[0015] The discharging rate during the discharging stage is C1 discharge , and the discharging time is T1 discharge ;

[0016] Rapid charge and discharge process for eliminating concentration polarization:

[0017] The charging rate during the charging stage is C2 charge , and the charging time is T2 charge ;

[0018] The rest time during the rest stage is T2 rest ;

[0019] The discharging rate during the discharging stage is C2 discharge , and the discharging time is T2 discharge ;

[0020] Among them, C1 charge = C1 discharge ; C2 charge = C2 discharge ; T1 charge = T1 discharge ; T2 charge = T2 discharge .

[0021] In the present invention, the charging rate and discharging rate of the rapid charge and discharge process with temperature rise and the rapid charge and discharge process for eliminating concentration polarization are the same, and the charge and discharge times are also the same, ensuring the charge and discharge balance of each temperature rise - concentration polarization elimination cycle and not affecting the original capacity of the battery.

[0022] Preferably, in the same temperature rise - concentration polarization elimination cycle, C2 charge < C1 charge . The present invention utilizes the process of each cycle to continuously eliminate the concentration polarization generated during the temperature rise while achieving the temperature rise. The specific process is to control the rapid charge and discharge C2 for eliminating concentration polarization charge to inhibit the lithium dendrites caused by the concentration polarization generated at both ends due to the large - rate charge and discharge in the rapid charge and discharge process with temperature rise in the same cycle. That is, the inhibition of lithium dendrites in the present invention is real - time and dynamic. When the lithium dendrites are in the budding stage, a Lorentz force - deflected electric field can be generated between the two electrodes of the battery through small - rate charge and discharge, thereby eliminating the lithium dendrites in the budding stage and stably inhibiting the lithium dendrites.

[0023] Preferably, for two adjacent temperature-rising - concentration polarization elimination cycles, C1 in the latter temperature-rising - concentration polarization elimination cycle charge is greater than C1 in the former temperature-rising - concentration polarization elimination cycle. charge Furthermore, the present invention preferably performs multiple temperature-rising - concentration polarization elimination cycles in chronological order, where C1 charge increases in an arithmetic progression, promoting continuous temperature increase and simultaneously improving the efficiency of self-preheating activation. The present invention utilizes continuously upgraded stepped temperature-rising - concentration polarization elimination cycles to continuously and gradually accelerate the generation and accumulation of heat, and simultaneously and synchronously continuously eliminate dynamically emerging lithium dendrites, quickly activate the battery within a short time, and eliminate the influence of low temperature on the charge and discharge performance of the battery.

[0024] Preferably, C1 in the first temperature-rising - concentration polarization elimination cycle charge ≤0.3C. Since the battery in the first cycle is completely in a non-activated state at low temperature, a smaller charging current is used to protect the battery. The present invention strictly controls the current magnitude in rapid charge and discharge during temperature rise. At low temperature, the internal resistance of the battery is large, and large-rate charge and discharge are prone to concentration polarization at both ends, resulting in the emergence of lithium dendrites. Therefore, by controlling the rate here, the growth of lithium dendrites is controlled during temperature rise.

[0025] Preferably, the preheating time of the multiple temperature-rising - concentration polarization elimination cycles is less than 10 min. The present invention utilizes an external power supply in cooperation, and the total self-preheating time does not exceed 10 min, that is, the battery is quickly activated within a short time, and the influence of low temperature on the charge and discharge performance of the battery is eliminated. The short self-preheating time of the present invention is conducive to the actual popularization and application of the present invention.

[0026] Preferably, C charge and C discharge are both less than or equal to 1C. In principle, the charge and discharge rate is not greater than 1C. When the charge and discharge rate exceeds 1C, serious concentration polarization will occur and cannot be eliminated, and lithium dendrites will grow rapidly, resulting in irreversible lithium dendrites and causing safety problems.

[0027] Preferably, it includes three temperature-rising - concentration polarization elimination cycles;

[0028] The first temperature-rising - concentration polarization elimination cycle:

[0029] Rapid charge and discharge process during temperature rise:

[0030] Charge from 0.3C to 0.5C for 30 s to 60 s;

[0031] Rest;

[0032] Discharge from 0.3C to 0.5C for 30 s to 60 s;

[0033] Fast charge and discharge process for eliminating concentration polarization:

[0034] Charge at 0.1C to 0.2C for 10s to 30s;

[0035] Rest;

[0036] Discharge at 0.1C to 0.2C for 10s to 30s;

[0037] The second temperature rise - eliminating concentration polarization cycle:

[0038] Temperature rise fast charge and discharge process:

[0039] Charge at 0.5C to 0.8C for 30s to 60s;

[0040] Rest;

[0041] Discharge at 0.5C to 0.8C for 30s to 60s;

[0042] Fast charge and discharge process for eliminating concentration polarization:

[0043] Charge at 0.2C to 0.3C for 10s to 30s;

[0044] Rest;

[0045] Discharge at 0.2C to 0.3C for 10s to 30s;

[0046] The third temperature rise - eliminating concentration polarization cycle:

[0047] Temperature rise fast charge and discharge process:

[0048] Charge at 0.7C to 1C for 30s to 60s;

[0049] Rest;

[0050] Discharge at 0.7C to 1C for 30s to 60s;

[0051] Fast charge and discharge process for eliminating concentration polarization:

[0052] Charge at 0.3C to 0.4C for 10s to 30s;

[0053] Rest;

[0054] Discharge at 0.3C to 0.4C for 10s to 30s.

[0055] The present invention utilizes the heating - eliminating concentration polarization cycle. The purpose of the rapid charge - discharge process during heating is to increase the temperature. Its rate is relatively large and increases in an arithmetic progression. The lower the ambient temperature, the lower the charge - discharge rate of the first rapid charge - discharge during heating. In principle, it is not less than 0.3C. Below 0.3C, the temperature rise is too small to achieve the purpose. At low temperatures, the internal resistance of the battery is large. High - rate charge and discharge are prone to concentration polarization at both ends and the appearance of lithium dendrites. Therefore, by controlling the rate here, while ensuring the temperature rise, the growth of lithium dendrites is controlled.

[0056] The purpose of the rapid charge - discharge for eliminating concentration polarization is to eliminate the concentration polarization generated by high - rate charge - discharge during each rapid charge - discharge process during heating and the lithium dendrites in the budding stage. Therefore, the charge - discharge rate of each rapid charge - discharge for eliminating concentration polarization is respectively less than the charge - discharge rate of the corresponding rapid charge - discharge process during heating. When the lithium dendrites are in the budding stage, small - rate charge - discharge can be used to generate a Lorentz force - deflected electric field between the two electrodes of the battery, thereby eliminating the lithium dendrites in the budding stage.

[0057] During the three - cycle process, the charge - discharge rates of the rapid charge - discharge process during heating increase in an arithmetic progression, and its charge - discharge time is less than the charge - discharge time of the corresponding rapid charge - discharge for eliminating concentration polarization, aiming to improve the working efficiency.

[0058] There is a certain time interval between two adjacent heating - eliminating concentration polarization cycles.

[0059] Preferably, C1 of the rapid charge - discharge during heating in the first to the third heating - eliminating concentration polarization cycles charge increases in an arithmetic progression;

[0060] Correspondingly, C2 of the rapid charge - discharge for eliminating concentration polarization in the first to the third heating - eliminating concentration polarization cycles charge increases in an arithmetic progression.

[0061] Preferably, the parameters of normal charge - discharge are 0.5C / 0.5C.

[0062] By adopting the above - mentioned technical solution, the beneficial effects of the present invention are as follows:

[0063] The present invention proposes a method for battery pre - heating. In a low - temperature environment, through rapid pulsed charge - discharge of the battery, the inherent temperature rise of the battery system is created during the charge - discharge process to increase the internal temperature of the battery, enhance the activity of the electrolyte and the positive and negative electrodes, reduce the influence of the external low temperature on the capacity loss during battery operation, activate the battery within a short time and put it into the working state. At the same time, after the temperature is increased, the probability of lithium plating of the battery can be reduced, the cycle life can be extended, the safety risk can be reduced, and the safety performance can be improved.

[0064] The battery preheated by the present invention has a uniform increase in the internal structure temperature, improved battery kinetic performance, can release more electric energy compared with the battery without preheating, enters the cycle under normal rate charge and discharge, has slow battery attenuation, and a high capacity retention rate;

[0065] The preheating method proposed by the present invention can effectively improve the problems of poor discharge performance, easy lithium precipitation, and poor cycle life of the battery at low temperatures.

[0066] Thus, the above object of the present invention is achieved. Brief Description of the Drawings

[0067] Figure 1 It is the surface temperature condition of the battery before and after cycling of the batteries obtained in Examples 1 to 4 and the comparative example in the present invention (the ordinate is -15°C to -25°C);

[0068] Figure 2 It is the surface condition of the electrode after disassembling the comparative example battery;

[0069] Figure 3 It is the surface condition of the electrode after disassembling the battery of Example 1;

[0070] Figure 4 It is the surface condition of the electrode after disassembling the battery of Example 2;

[0071] Figure 5 It is the surface condition of the electrode after disassembling the battery of Example 3;

[0072] Figure 6 It is the surface condition of the electrode after disassembling the battery of Example 4. Detailed Embodiments

[0073] In order to further explain the technical solution of the present invention, the present invention will be elaborated in detail through specific embodiments below.

[0074] Example 1

[0075] This example discloses a self-preheating method for a lithium-ion battery. A 2600 mAh cylindrical battery is in an environment of -30°C, and it is electrically connected to the battery to be preheated through an external power supply for multiple heating - eliminating concentration polarization cycles. Each heating - eliminating concentration polarization cycle includes a heating rapid charge and discharge and an eliminating concentration polarization rapid charge and discharge;

[0076] Among them, the rapid charge and discharge for heating rapid charge and discharge or eliminating concentration polarization includes a charging stage, a rest stage, and a discharging stage;

[0077] The first heating - eliminating concentration polarization cycle;

[0078] The heating rapid charge and discharge process,

[0079] The charging rate during the charging stage is 0.3C, and the charging time is 30s;

[0080] The rest time during the rest stage is 1s;

[0081] The discharging rate during the discharging stage is 0.3C, and the discharging time is 30s;

[0082] The fast charge-discharge process for eliminating concentration polarization,

[0083] The charging rate during the charging stage is 0.1C, and the charging time is 10s;

[0084] The rest time during the rest stage is 1s;

[0085] The discharging rate during the discharging stage is 0.1C, and the discharging time is 10s;

[0086] The second heating-eliminating concentration polarization cycle;

[0087] The heating fast charge-discharge process,

[0088] The charging rate during the charging stage is 0.5C, and the charging time is 30s;

[0089] The rest time during the rest stage is 1s;

[0090] The discharging rate during the discharging stage is 0.5C, and the discharging time is 30s;

[0091] The fast charge-discharge process for eliminating concentration polarization,

[0092] The charging rate during the charging stage is 0.2C, and the charging time is 10s;

[0093] The rest time during the rest stage is 1s;

[0094] The discharging rate during the discharging stage is 0.2C, and the discharging time is 10s;

[0095] The third heating-eliminating concentration polarization cycle;

[0096] The heating fast charge-discharge process,

[0097] The charging rate during the charging stage is 0.7C, and the charging time is 30s;

[0098] The rest time during the rest stage is 1s;

[0099] The discharging rate during the discharging stage is 0.7C, and the discharging time is 30s;

[0100] The fast charge-discharge process for eliminating concentration polarization,

[0101] The charging rate during the charging stage is 0.3C, and the charging time is 10s;

[0102] The rest time during the rest stage is 1 s;

[0103] The discharge rate during the discharge stage is 0.3 C, and the discharge time is 10 s;

[0104] The interval between two adjacent temperature rise - concentration polarization elimination cycles is 1 s.

[0105] Example 2

[0106] The main difference between this example and Example 1 lies in:

[0107] The first temperature rise - concentration polarization elimination cycle;

[0108] The rapid charge - discharge process of temperature rise,

[0109] The charge rate during the charge stage is 0.4 C, and the charge time is 40 s;

[0110] The rest time during the rest stage is 1 s;

[0111] The discharge rate during the discharge stage is 0.4 C, and the discharge time is 40 s;

[0112] The rapid charge - discharge process of eliminating concentration polarization,

[0113] The charge rate during the charge stage is 0.2 C, and the charge time is 20 s;

[0114] The rest time during the rest stage is 1 s;

[0115] The discharge rate during the discharge stage is 0.2 C, and the discharge time is 20 s;

[0116] The second temperature rise - concentration polarization elimination cycle;

[0117] The rapid charge - discharge process of temperature rise,

[0118] The charge rate during the charge stage is 0.6 C, and the charge time is 40 s;

[0119] The rest time during the rest stage is 1 s;

[0120] The discharge rate during the discharge stage is 0.6 C, and the discharge time is 40 s;

[0121] The rapid charge - discharge process of eliminating concentration polarization,

[0122] The charge rate during the charge stage is 0.3 C, and the charge time is 20 s;

[0123] The rest time during the rest stage is 1 s;

[0124] The discharge rate during the discharge stage is 0.3 C, and the discharge time is 20 s;

[0125] The third temperature increase - concentration polarization elimination cycle;

[0126] The temperature increase rapid charge - discharge process,

[0127] The charging rate in the charging stage is 0.8C, and the charging time is 40s;

[0128] The rest time in the rest stage is 1s;

[0129] The discharging rate in the discharging stage is 0.8C, and the discharging time is 40s;

[0130] The rapid charge - discharge process for eliminating concentration polarization,

[0131] The charging rate in the charging stage is 0.4C, and the charging time is 20s;

[0132] The rest time in the rest stage is 1s;

[0133] The discharging rate in the discharging stage is 0.4C, and the discharging time is 20s;

[0134] The interval between two adjacent temperature increase - concentration polarization elimination cycles is 1s.

[0135] Example 3

[0136] The main difference between this example and Example 1 is:

[0137] The first temperature increase - concentration polarization elimination cycle;

[0138] The temperature increase rapid charge - discharge process,

[0139] The charging rate in the charging stage is 0.5C, and the charging time is 50s;

[0140] The rest time in the rest stage is 1s;

[0141] The discharging rate in the discharging stage is 0.5C, and the discharging time is 50s;

[0142] The rapid charge - discharge process for eliminating concentration polarization,

[0143] The charging rate in the charging stage is 0.2C, and the charging time is 30s;

[0144] The rest time in the rest stage is 1s;

[0145] The discharging rate in the discharging stage is 0.2C, and the discharging time is 30s;

[0146] The second temperature increase - concentration polarization elimination cycle;

[0147] The temperature increase rapid charge - discharge process,

[0148] The charging rate during the charging stage is 0.7C, and the charging time is 50s;

[0149] The rest time during the rest stage is 1s;

[0150] The discharging rate during the discharging stage is 0.7C, and the discharging time is 50s;

[0151] The fast charge-discharge process for eliminating concentration polarization,

[0152] The charging rate during the charging stage is 0.3C, and the charging time is 30s;

[0153] The rest time during the rest stage is 1s;

[0154] The discharging rate during the discharging stage is 0.3C, and the discharging time is 30s;

[0155] The third heating-eliminating concentration polarization cycle;

[0156] The heating fast charge-discharge process,

[0157] The charging rate during the charging stage is 0.9C, and the charging time is 50s;

[0158] The rest time during the rest stage is 1s;

[0159] The discharging rate during the discharging stage is 0.9C, and the discharging time is 50s;

[0160] The fast charge-discharge process for eliminating concentration polarization,

[0161] The charging rate during the charging stage is 0.4C, and the charging time is 30s;

[0162] The rest time during the rest stage is 1s;

[0163] The discharging rate during the discharging stage is 0.4C, and the discharging time is 30s;

[0164] The interval between two adjacent heating-eliminating concentration polarization cycles is 1s.

[0165] Example 4

[0166] The main difference between this example and Example 1 is:

[0167] The first heating-eliminating concentration polarization cycle;

[0168] The heating fast charge-discharge process,

[0169] The charging rate during the charging stage is 0.4C, and the charging time is 60s;

[0170] The rest time during the rest stage is 1s;

[0171] The discharge rate during the discharge stage is 0.4C, and the discharge time is 60s;

[0172] A rapid charge-discharge process for eliminating concentration polarization,

[0173] The charge rate during the charging stage is 0.2C, and the charging time is 30s;

[0174] The rest time during the rest stage is 1s;

[0175] The discharge rate during the discharge stage is 0.2C, and the discharge time is 30s;

[0176] The second temperature rise - concentration polarization elimination cycle;

[0177] A rapid charge-discharge process for temperature rise,

[0178] The charge rate during the charging stage is 0.7C, and the charging time is 60s;

[0179] The rest time during the rest stage is 1s;

[0180] The discharge rate during the discharge stage is 0.7C, and the discharge time is 60s;

[0181] A rapid charge-discharge process for eliminating concentration polarization,

[0182] The charge rate during the charging stage is 0.3C, and the charging time is 30s;

[0183] The rest time during the rest stage is 1s;

[0184] The discharge rate during the discharge stage is 0.3C, and the discharge time is 30s;

[0185] The third temperature rise - concentration polarization elimination cycle;

[0186] A rapid charge-discharge process for temperature rise,

[0187] The charge rate during the charging stage is 1C, and the charging time is 60s;

[0188] The rest time during the rest stage is 1s;

[0189] The discharge rate during the discharge stage is 1C, and the discharge time is 60s;

[0190] A rapid charge-discharge process for eliminating concentration polarization,

[0191] The charge rate during the charging stage is 0.4C, and the charging time is 30s;

[0192] The rest time during the rest stage is 1s;

[0193] The discharge rate during the discharge stage is 0.4C, and the discharge time is 30s;

[0194] The interval between two adjacent heating - eliminating concentration polarization cycles is 1 s.

[0195] Comparative example

[0196] A 2600 mAh cylindrical battery at - 30 °C does not go through a non - preheating stage.

[0197] The self - preheating batteries of Examples 1 to 4 and the batteries without self - preheating in the comparative example are respectively subjected to 0.5C / 0.5C charge and discharge; for the batteries undergoing charge and discharge, a temperature rise test is carried out. The specific test method is as follows:

[0198] Thermocouples are attached to the surface of each group of batteries, and a multi - channel tester is used to record the temperature rise of the battery every 30 s during the first discharge. The specific temperature rise conditions are shown in Figure 1 as follows. From Figure 1 the temperature curves, it can be seen that before the normal working discharge (the vertical black straight line in the figure) of Examples 1 - 4, the surface temperature of the batteries in Examples 1 to 4 has already increased, while the surface temperature of the comparative batteries starts to increase only after the working discharge. This proves that the preheating method proposed in the present invention can increase the surface temperature of the battery from the inside out before the normal working charge and discharge of the battery. The batteries of Examples 1 to 4 and the comparative example are subjected to 10 cycles of 0.5C / 0.5C charge and discharge, then fully charged, disassembled, and the lithium deposition on the negative electrode is recorded respectively Figures 2 to 6 as shown in Table 1.

[0199] Table 1 Lithium deposition conditions of the batteries of Examples 1 to 4 and the comparative example

[0200] Group Electrode surface condition Comparative example Lithium deposition on the surface, see Figure 2 Example 1 No lithium deposition on the surface, see Figure 3 Example 2 No lithium deposition on the surface, see Figure 4 Example 3 No lithium deposition on the surface, see Figure 5 Example 4 No lithium deposition on the surface, see Figure 6

[0201] Combined with Table 1 and Figures 2 to 6 it can be known that in the case of the comparative batteries without preheating, directly performing charge and discharge at the working current, lithium deposition appears on the surface of the negative electrode of the battery. The white part in the picture is the deposited lithium; after the batteries of Examples 1 to 4 are preheated, the internal temperature of the batteries rises effectively and evenly, and the kinetic performance of the positive and negative electrode materials and the electrolyte has been improved. In this case, when performing charge and discharge at the working current, the balance of lithium ion insertion and extraction between the positive and negative electrodes is maintained, so lithium deposition is not likely to occur, and the surface of the electrode sheet is golden yellow and smooth. This proves that the preheating method proposed in the present invention can effectively improve lithium deposition.

[0202] The batteries of Examples 1 to 4 and the comparative example are subjected to a cycle life test. The specific test method is to record the capacity change of the batteries for 10 cycles of 0.5C / 0.5C at - 30 °C. The specific data are shown in Table 2.

[0203] Table 2 Cycle data of the batteries of Examples 1 to 4 and the comparative example

[0204]

[0205] Further combined with Table 2 and Figure 1 It can be seen that the discharge capacity of the battery without preheating in the first week at low temperature is only 59% of the original capacity. Moreover, during the subsequent cycling process, the battery capacity decays rapidly. This proves that at low temperature, the battery kinetics is poor, the lithium ion conduction is blocked, the discharged electricity is small, and the cycle life is poor. The batteries of Examples 1-4 are preheated, the internal temperature rises, and the battery kinetics performance is improved. Therefore, more electricity can be discharged. The batteries corresponding to Examples 1 to 4 can discharge 89% of the original capacity in the first week, and during the subsequent cycling process, the battery decays slowly.

[0206] It can be proved from the above data that the preheating method proposed by the present invention can effectively improve the problems of poor discharge performance, easy lithium deposition, and poor cycle life of the battery at low temperature.

Claims

1. A self-preheating method for a lithium-ion battery, where the battery is at -20°C to -30°C, characterized in that: Electrically connect to the battery to be preheated through an external power supply for multiple heating - concentration polarization elimination cycles. Each heating - concentration polarization elimination cycle includes a heating rapid charge - discharge and a concentration polarization elimination rapid charge - discharge; Among them, the rapid charge - discharge for heating and the rapid charge - discharge for concentration polarization elimination respectively include a charging stage, a rest stage, and a discharging stage; The charging rate during the charging stage is C charge , and the charging time is T charge ; The rest time during the rest phase is T rest ; The discharge rate during the discharge stage is C discharge , and the discharge time is T discharge ; After the battery temperature is increased through multiple heating - concentration polarization elimination cycles, the battery is charged and discharged normally; The parameters for normal charge - discharge are 0.5C / 0.5C; The same heating - concentration polarization elimination cycle includes: Heating rapid charge - discharge process: The charging rate during the charging stage is C1 charge , and the charging time is T1 charge ; The rest time during the rest phase is T1 rest ; The discharge rate during the discharge stage is C1 discharge , and the discharge time is T1 discharge ; Rapid charge - discharge process for concentration polarization elimination: The charging rate during the charging stage is C2 charge , and the charging time is T2 charge ; The rest time during the rest phase is T2 rest ; The discharge rate during the discharge stage is C2 discharge , and the discharge time is T2 discharge ; Among them, C1 charge = C1 discharge ; C2 charge = C2 discharge ; T1 charge = T1 discharge ; T2 charge = T2 discharge ; During the same heating - eliminating concentration polarization cycle, C2 charge <C1 charge ; For two adjacent temperature increase - concentration polarization elimination cycles, C1 in the latter temperature increase - concentration polarization elimination cycle charge is greater than C1 in the former temperature increase - concentration polarization elimination cycle charge ; C1 in the first heating - concentration polarization elimination cycle charge ≤0.3C; C charge and C discharge are both less than or equal to 1C.

2. The self-preheating method of a lithium-ion battery according to claim 1, characterized in that: The preheating time of the multiple heating - concentration polarization elimination cycles is less than 10 min.

3. The self-preheating method of a lithium-ion battery according to claim 1, characterized in that: Including three heating - concentration polarization elimination cycles; The first heating - concentration polarization elimination cycle: Heating rapid charge - discharge process: Charge from 0.3C to 0.5C for 30 s to 60 s; Rest; Discharge from 0.3C to 0.5C for 30 - 60 s; Rapid charge - discharge process for concentration polarization elimination: Charge from 0.1C to 0.2C for 10 s to 30 s; Rest; Discharge from 0.1 - 0.2C for 10 - 30 s; The second heating - concentration polarization elimination cycle: Heating rapid charge - discharge process: Charge from 0.5C to 0.8C for 30 s to 60 s; Rest; Discharge from 0.5C to 0.8C for 30 s to 60 s; Rapid charge - discharge process for concentration polarization elimination: Charge from 0.2C to 0.3C for 10 s to 30 s; Rest; Discharge from 0.2C to 0.3C for 10 s to 30 s; The third heating - concentration polarization elimination cycle: Heating rapid charge - discharge process: Charge from 0.7C to 1C for 30 s to 60 s; Rest; Discharge from 0.7C to 1C for 30 s to 60 s; Rapid charge - discharge process for concentration polarization elimination: Charge from 0.3C to 0.4C for 10 s to 30 s; Rest; Discharge from 0.3C to 0.4C for 10 s to 30 s.

4. The self-preheating method of a lithium-ion battery according to claim 3, wherein: C1 for the rapid charge and discharge during heating in the first to third heating - eliminating concentration polarization cycles charge increase in an arithmetic progression; Correspondingly, C2 of the rapid charge and discharge for eliminating concentration polarization in the first to third heating - eliminating concentration polarization cycles charge increases in an arithmetic progression.

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