Charging method for lithium ion battery in low-temperature environment

Abstract

The invention discloses a charging method for a lithium ion battery in a low-temperature environment, and the method specifically comprises a charging system assembling step, a battery heating step through charging and discharging, and a normal charging step, the battery heating step through charging and discharging specifically comprises the following steps: firstly standing the battery for 2 seconds; the charging cabinet carries out constant-current charging on the battery, the charging current of the constant-current charging is 0.15-0.3 C (mA), and the constant-current charging time is 30-50 s; after the constant-current charging is completed, standing the battery for 2 seconds; the charging cabinet conducts constant-current discharging on the battery, the discharging current of constant-current discharging is 0.15-0.3 C (mA), and the constant-current discharging time is 40 s; then the operation is cycled until the surface temperature of the battery is higher than 5 DEG C; the method is suitable for charging the lithium ion battery under the low-temperature condition of-20 DEG C to 0 DEG C, the principle that the lithium ion battery generates heat during charging and discharging is utilized, and shallow charging and shallow discharging are circularly performed, so that the temperature of the battery is gradually increased.

Description

Technical Field

[0001] The present invention relates to a method for charging a lithium battery, specifically, a charging method for a lithium-ion battery in a low-temperature environment, belonging to the technical field of new energy batteries. Background Art

[0002] In recent years, with the increasingly scarce petroleum resources, the new energy industry has received more and more attention, and lithium-ion batteries have become a national key research project.

[0003] The low-temperature performance of lithium-ion batteries has always been a bottleneck restricting the further development of lithium-ion batteries. Especially when charging lithium-ion batteries under low-temperature conditions, the lithium intercalation kinetics conditions at the negative electrode become worse, the specific capacity of the negative electrode decreases, and lithium plating is likely to occur during charging, forming a lithium coating or even lithium dendrites on the surface of the negative electrode, resulting in capacity loss and safety hazards of the lithium battery.

[0004] Currently, under low-temperature conditions, generally a heater is added to heat up the battery, and charging starts after the surface of the battery reaches a certain temperature. The Chinese patent with the patent application number: CN202011147539.1 discloses a charging method for a lithium-ion battery in a low-temperature environment. This method specifically includes steps of assembling a charging system, charging and discharging to heat up the battery, and normal charging; the step of assembling the charging system includes: S1. The charging system includes a charging cabinet and a management system. The management system includes a temperature detection device. The monitoring point of the temperature detection device is connected to the battery. The management system obtains the surface temperature of the battery through the temperature detection device. The output end of the charging cabinet is connected to the positive and negative electrodes of the lithium-ion battery to be charged; S2. When the surface temperature of the battery detected by the management system is 15°C < T < 0°C, the step of charging and discharging to heat up the battery is carried out; The present invention is applicable to use in a low-temperature environment of 15°C to 0°C, mainly utilizes the heat generation principle of lithium-ion batteries during charging and discharging to automatically heat up the battery, and avoids the phenomenon of lithium plating during charging of the battery under low-temperature conditions.

[0005] The above-mentioned lithium-ion battery pack charging and heating system and heating method can heat the inside and outside of the battery pack simultaneously by discharging the battery pack and adding a heating device outside the battery pack and making them work simultaneously, which is convenient for charging. However, when the existing battery charging method is used for charging and discharging in a low-temperature environment, if the current is too large or the time is too long, the phenomenon of lithium plating will occur, and the lithium ions in the lithium-ion battery will dissociate into the electrolyte and no longer be recycled, resulting in capacity loss and safety hazards. Summary of the Invention

[0006] The main technical problem to be solved by the present invention is to provide a charging method for a lithium-ion battery applicable to low-temperature conditions of -20°C to 0°C. By using the principle of self-heating during the charge and discharge of the lithium-ion battery, shallow charge and discharge are cycled to gradually increase the temperature of the battery, which not only avoids lithium precipitation in the lithium-ion battery under low-temperature conditions but also does not require an additional heater in a low-temperature environment for charging the lithium-ion battery.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: A charging method for a lithium-ion battery in a low-temperature environment, which specifically includes steps of assembling a charging system, charging and discharging to increase the battery temperature, and normal charging; The step of assembling the charging system includes: S1. The charging system includes a charging cabinet and a management system. The management system includes a temperature detection device. The temperature detection line of the temperature detection device is connected to the battery. The management system obtains the surface temperature of the battery through the temperature detection device. The output end of the charging cabinet is connected to the positive and negative electrodes of the lithium-ion battery to be charged; S2. When the surface temperature of the battery detected by the management system satisfies -20°C < T < 0°C, perform the step of charging and discharging to increase the battery temperature; The step of charging and discharging to increase the battery temperature specifically includes: S3. First, let the battery stand for 2 s, and then perform step S4; S4. The charging cabinet performs constant-current charging on the battery. The charging current for constant-current charging is 0.15 - 0.3C (mA), and the constant-current charging time is 30 - 50 s, where "C" represents the rated capacity of the battery; S5. After the constant-current charging is completed, let the battery stand for 2 s, and then perform step S6; S6. The charging cabinet performs constant-current discharging on the battery. The discharging current for constant-current discharging is 0.15 - 0.3C (mA), and the constant-current discharging time is 40 s, where "C" represents the rated capacity of the battery; Then, cycle through steps S4, S5, and S6, and the number of cycles is 100 times.

[0008] Further optimization: In the step of charging and discharging to increase the battery temperature, the management system real-time detects the surface temperature of the battery. When the surface temperature of the battery is lower than 5°C after the step of charging and discharging to increase the battery temperature is completed, repeat the step of charging and discharging to increase the battery temperature until the surface temperature of the battery is higher than 5°C.

[0009] Further optimization: The steps of this method further include: S7. The management system real-time detects the surface temperature of the battery. When the surface temperature of the battery is higher than 5°C, end the step of charging and discharging to increase the battery temperature and perform the normal charging step.

[0010] Further optimization: In step S7, the management system continuously detects the surface temperature of the battery. When the surface temperature of the battery is higher than 5°C, the management system sends an instruction to the charging cabinet to end the charge-discharge process for battery warming. After that, the management system sends an instruction to the charging cabinet to perform the normal charging process.

[0011] Further optimization: The normal charging process specifically includes: S8. First, the battery 1 after the charge-discharge process for battery warming ends is left to stand for 30 s, and then step S9 is executed; S9. The charging cabinet performs constant-current charging on the battery. During constant-current charging, the charging current is 0.15 - 0.3C (mA), and the voltage is restricted. The constant-current charging time is 40 - 60 min, where "C" represents the rated capacity of the battery; S10. The charging cabinet performs further constant-current charging on the battery. The charging current for this constant-current charging is 0.25 - 0.45C (mA), and the voltage is restricted. The charging time for this constant-current charging is 200 min, where "C" represents the rated capacity of the battery; S11. The charging cabinet performs constant-voltage charging on the battery. The charging current for this constant-voltage charging is 0.25 - 0.45C, and the voltage is restricted. The restricted current is 0.03C, and the charging ends.

[0012] Further optimization: In step S9, the restricted voltage for the lithium iron phosphate battery is 3800 (mV), and the restricted voltage for the ternary battery is 4500 (mV).

[0013] Further optimization: In step S10, the restricted voltage for the lithium iron phosphate battery is 3800 (mV), and the restricted voltage for the ternary battery is 4500 (mV).

[0014] With the above technical solution, the present invention is ingeniously conceived, applicable to use in a low-temperature environment of -15°C to 0°C, and is convenient to use. It mainly utilizes the heat generation principle during the charge and discharge of lithium-ion batteries, performs shallow charge and discharge in a cycle to automatically warm the battery, which not only avoids the lithium plating phenomenon during charging of lithium-ion batteries under low-temperature conditions, does not affect the cycle life of lithium-ion batteries, but also can use the heat generated by the lithium-ion battery itself to increase the battery temperature. After the temperature reaches a certain value, conventional high-current discharge is performed, which is convenient to use, saves the additional heater for warming the battery, and greatly reduces the production and use costs.

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0017] In the figure: 1 - battery, 2 - charging cabinet; 3 - management system; 4 - temperature detection line. Detailed implementation mode

[0018] Example 1: Please refer to Figure 1 , a charging method for lithium-ion batteries in a low-temperature environment, which specifically includes the steps of assembling a charging system, charging and discharging to warm up the battery, and normal charging steps; The steps of assembling the charging system include: S1. The charging system includes a charging cabinet 2 and a management system 3. The management system 3 includes a temperature detection device. The temperature detection line 4 of the temperature detection device is connected to the battery 1. The management system 3 obtains the surface temperature of the battery 1 through the temperature detection line 4 of the temperature detection device.

[0019] In step S1, the monitoring point of the temperature detection device is installed in the middle part of the battery 1 to improve the accuracy of the detection data and facilitate use.

[0020] Both the charging cabinet 2 and the management system 3 in the charging system are existing technologies, which can be directly purchased on the market and can be automatically controlled through programming.

[0021] In step S1, the output end of the charging cabinet 2 is connected to the positive and negative electrodes of the lithium-ion battery 1 to be charged.

[0022] S2. When the surface temperature of the battery 1 detected by the management system 3 is 0 °C, the management system 3 sends an instruction to the charging cabinet 2 to perform the steps of charging and discharging to warm up the battery.

[0023] In step S2, when the surface temperature of the battery 1 detected by the management system 3 is lower than -20 °C, the management system 3 sends an instruction to the charging cabinet 2 not to start the steps of charging and discharging to warm up the battery.

[0024] The steps of charging and discharging to warm up the battery specifically include: S3. First, the battery 1 is left standing for 2 s, and then step S4 is executed.

[0025] S4. The charging cabinet 2 performs constant-current charging on the battery 1. The charging current during the constant-current charging is 0.15C (mA), and the constant-current charging time is 50 s, where "C" represents the rated capacity of the battery 1.

[0026] The charging current of 0.15C (mA) in step S4 means that the charging current is the rated capacity of the battery * 0.15 (mA).

[0027] S5. After the constant-current charging is completed, the battery 1 is left standing for 2 s, and then step S6 is executed.

[0028] S6. The charging cabinet 2 discharges the battery 1 at a constant current. During the constant-current discharge, the discharge current is 0.15C (mA), and the constant-current discharge time is 40 s, where "C" represents the rated capacity of the battery 1.

[0029] Then, steps S4, S5, and S6 are cycled, and the number of cycles is 100 times.

[0030] The discharge current of 0.15C (mA) in step S6 means that the discharge current is the rated capacity of the battery * 0.15 (mA).

[0031] In the step of heating the battery by charge and discharge, the management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is still lower than 5°C after the step of heating the battery by charge and discharge ends, the management system 3 will continue to send instructions to the charging cabinet 2 to repeat the step of heating the battery by charge and discharge until the surface temperature of the battery 1 is higher than 5°C.

[0032] S7. The management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is higher than 5°C, the step of heating the battery by charge and discharge ends, and the normal charging step is carried out.

[0033] In step S7, the management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is higher than 5°C, the management system 3 sends an instruction to the charging cabinet 2 to end the step of heating the battery by charge and discharge. After that, the management system 3 sends an instruction to the charging cabinet 2 to carry out the normal charging step.

[0034] The normal charging step includes: S8. First, the battery 1 after the step of heating the battery by charge and discharge ends is left standing for 30 s, and then step S9 is executed.

[0035] S9. The charging cabinet 2 charges the battery 1 at a constant current. During the constant-current charging, the charging current is 0.15C (mA), and the voltage is limited. The constant-current charging time is 60 min, where "C" represents the rated capacity of the battery 1.

[0036] The charging current of 0.15C (mA) in step S9 means that the charging current is the rated capacity of the battery * 0.15 (mA).

[0037] In step S9, the limited voltage for the lithium iron phosphate battery is 3800 (mV), and the limited voltage for the ternary battery is 4500 (mV).

[0038] S10. The charging cabinet 2 further charges the battery 1 at a constant current. The charging current of this constant-current charging is 0.25C (mA), and the voltage is limited. The charging time of this constant-current charging is 200 min, where "C" represents the rated capacity of the battery 1.

[0039] The charging current in step S10 being 0.25C (mA) means: the charging current is the battery's rated capacity * 0.25 (mA).

[0040] The defined voltage for the lithium iron phosphate battery in step S10 is 3800 (mV), and the defined voltage for the ternary battery is 4500 (mV).

[0041] S11. The charging cabinet 2 performs constant - voltage charging on the battery 1. The charging current for this constant - voltage charging is 0.25C (mA), and the voltage is restricted, where the restricted current is 0.03C, and the charging ends.

[0042] The charging current in step S11 being 0.25C (mA) means: the charging current is the battery's rated capacity * 0.25 (mA).

[0043] Adopting the above - mentioned technical solution, the present invention is ingeniously conceived, applicable to use in a low - temperature environment of - 15°C to 0°C, and is convenient to use. It mainly utilizes the heat - generation principle during the charge - discharge process of lithium - ion batteries, cycles through shallow charge and shallow discharge to automatically raise the battery temperature. This not only avoids the phenomenon of lithium plating during charging of lithium - ion batteries under low - temperature conditions, but also does not affect the cycle life of lithium - ion batteries. Moreover, it can utilize the heat generated by the lithium - ion battery itself to increase the battery temperature, and perform conventional high - current discharge after the temperature reaches a certain value, which is convenient to use, saves the additional heater for raising the battery temperature, and greatly reduces the production and use costs.

[0044] Example 2: Please refer to Figure 1 , a charging method for lithium - ion batteries in a low - temperature environment, which specifically includes steps of assembling a charging system, charging and discharging to raise the battery temperature, and normal charging; The steps of assembling the charging system include: S1. The charging system includes a charging cabinet 2 and a management system 3. The management system 3 includes a temperature - detection device. The temperature - detection line 4 of the temperature - detection device is connected to the battery 1. The management system 3 obtains the surface temperature of the battery 1 through the temperature - detection line 4 of the temperature - detection device. The monitoring point of the temperature - detection device is installed in the middle part of the battery 1 to improve the accuracy of the detection data, which is convenient to use. The output end of the charging cabinet 2 is connected to the positive and negative electrodes of the lithium - ion battery 1 to be charged.

[0045] Both the charging cabinet 2 and the management system 3 in this charging system are existing technologies, which can be directly purchased on the market and can be programmed to achieve automatic control.

[0046] S2. When the surface temperature of the battery 1 detected by the management system 3 is -7.5°C, the management system 3 sends an instruction to the charging cabinet 2 to perform the charge and discharge steps to increase the battery temperature. When the surface temperature of the battery 1 detected by the management system 3 is lower than -15°C, the management system 3 sends an instruction to the charging cabinet 2 not to start the charge and discharge steps to increase the battery temperature.

[0047] The charge and discharge steps to increase the battery temperature specifically include: S3. First, the battery 1 is left stationary for 2 s, and then step S4 is executed.

[0048] S4. The charging cabinet 2 performs constant current charging on the battery 1. During the constant current charging, the charging current is 0.2C (mA), and the constant current charging time is 40 s. Here, "C" represents the rated capacity of the battery 1. The charging current of 0.2C (mA) means that the charging current is the rated capacity of the battery * 0.2 (mA).

[0049] S5. After the constant current charging is completed, the battery 1 is left stationary for 2 s, and then step S6 is executed.

[0050] S6. The charging cabinet 2 performs constant current discharging on the battery 1. During the constant current discharging, the discharging current is 0.2C (mA), and the constant current discharging time is 40 s. Here, "C" represents the rated capacity of the battery 1. The discharging current of 0.2C (mA) means that the discharging current is the rated capacity of the battery * 0.2 (mA).

[0051] Then steps S4, S5, and S6 are cycled, and the number of cycles is 100 times.

[0052] During the charge and discharge steps to increase the battery temperature, the management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is still lower than 5°C after the charge and discharge steps to increase the battery temperature are completed, the management system 3 will continue to send an instruction to the charging cabinet 2 to repeat the charge and discharge steps to increase the battery temperature until the surface temperature of the battery 1 is higher than 5°C.

[0053] S7. The management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is higher than 5°C, the charge and discharge steps to increase the battery temperature are ended, and the normal charging steps are performed.

[0054] In step S7, the management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is higher than 5°C, the management system 3 sends an instruction to the charging cabinet 2 to end the charge and discharge steps to increase the battery temperature. After that, the management system 3 sends an instruction to the charging cabinet 2 to perform the normal charging steps.

[0055] The normal charging steps include: S8. First, the battery 1 after the charge and discharge steps to increase the battery temperature are completed is left stationary for 30 s, and then step S9 is executed.

[0056] S9. The charging cabinet 2 performs constant-current charging on the battery 1. During constant-current charging, the charging current is 0.2C (mA), and the voltage is limited. The constant-current charging time is 50 min, where "C" represents the rated capacity of the battery 1. The charging current of 0.2C (mA) means that the charging current is the rated capacity of the battery * 0.2 (mA).

[0057] In step S9, the limited voltage for the lithium iron phosphate battery is 3800 (mV), and the limited voltage for the ternary battery is 4500 (mV).

[0058] S10. The charging cabinet 2 performs further constant-current charging on the battery 1. The charging current of this constant-current charging is 0.35C (mA), and the voltage is limited. The charging time of this constant-current charging is 200 min, where "C" represents the rated capacity of the battery 1. The charging current of 0.35C (mA) means that the charging current is the rated capacity of the battery * 0.35 (mA).

[0059] In step S10, the limited voltage for the lithium iron phosphate battery is 3800 (mV), and the limited voltage for the ternary battery is 4500 (mV).

[0060] S11. The charging cabinet 2 performs constant-voltage charging on the battery 1. The charging current of this constant-voltage charging is 0.35C (mA), and the voltage is limited. The limited current is 0.03C, and the charging ends. Here, "C" represents the rated capacity of the battery 1. The charging current of 0.35C (mA) means that the charging current is the rated capacity of the battery * 0.35 (mA).

[0061] With the above technical solution, the present invention is ingeniously conceived, suitable for use in a low-temperature environment of -15°C to 0°C, and is convenient to use. It mainly utilizes the heat generation principle of lithium-ion batteries during charge and discharge, performs shallow charge and discharge cyclically to make the battery automatically warm up, which not only avoids the phenomenon of lithium deposition during charging of lithium-ion batteries under low-temperature conditions, does not affect the cycle life of lithium-ion batteries, but also can utilize the heat generated by the lithium-ion battery itself to increase the battery temperature. After the temperature reaches a certain value, conventional high-current discharge is carried out, which is convenient to use, saves the additional heater for warming up the battery, and greatly reduces the production and use costs.

[0062] Example 3: Please refer to Figure 1 , a charging method for lithium-ion batteries in a low-temperature environment, which specifically includes steps of assembling a charging system, charging and discharging to warm up the battery, and normal charging; The steps of assembling the charging system include: S1. The charging system includes a charging cabinet 2 and a management system 3. The management system 3 includes a temperature detection device. The temperature detection line 4 of the temperature detection device is connected to the battery 1. The management system 3 obtains the surface temperature of the battery 1 through the temperature detection line 4 of the temperature detection device. The monitoring point of the temperature detection device is installed in the middle part of the battery 1 to improve the accuracy of the detection data and facilitate use. The output end of the charging cabinet 2 is connected to the positive and negative electrodes of the lithium-ion battery 1 to be charged.

[0063] Both the charging cabinet 2 and the management system 3 in the charging system are existing technologies and can be directly purchased on the market, and both can be automatically controlled through programming.

[0064] S2. When the surface temperature of the battery 1 detected by the management system 3 is 0 °C, the management system 3 issues an instruction to the charging cabinet 2 to perform the charge and discharge step to raise the temperature of the battery. When the surface temperature of the battery 1 detected by the management system 3 is lower than -15 °C, the management system 3 issues an instruction to the charging cabinet 2 not to start the charge and discharge step to raise the temperature of the battery.

[0065] The charge and discharge step to raise the temperature of the battery specifically includes: S3. First, the battery 1 is static for 2 s, and then step S4 is executed.

[0066] S4. The charging cabinet 2 performs constant current charging on the battery 1. During the constant current charging, the charging current is 0.3C (mA), and the constant current charging time is 30 s. Here, "C" represents the rated capacity of the battery 1. The charging current of 0.3C (mA) means that the charging current is the rated capacity of the battery * 0.3 (mA).

[0067] S5. After the constant current charging is completed, the battery 1 is static for 2 s, and then step S6 is executed.

[0068] S6. The charging cabinet 2 performs constant current discharging on the battery 1. During the constant current discharging, the discharging current is 0.3C (mA), and the constant current discharging time is 40 s. Here, "C" represents the rated capacity of the battery 1. The discharging current of 0.3C (mA) means that the discharging current is the rated capacity of the battery * 0.3 (mA).

[0069] Then, steps S4, S5, and S6 are cycled, and the number of cycles is 100 times.

[0070] During the charge and discharge step to raise the temperature of the battery, the management system 3 real-time detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is still lower than 5 °C after the charge and discharge step to raise the temperature of the battery ends, the management system 3 will continue to issue an instruction to the charging cabinet 2 to repeat the charge and discharge step to raise the temperature of the battery until the surface temperature of the battery 1 is higher than 5 °C.

[0071] S7. The management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is higher than 5°C, the charge-discharge to heat up the battery step is ended, and the normal charging step is carried out.

[0072] In the step S7, the management system 3 continuously detects the surface temperature of the battery 1. When the surface temperature of the battery 1 is higher than 5°C, the management system 3 issues an instruction to the charging cabinet 2 to end the charge-discharge to heat up the battery step. After that, the management system 3 issues an instruction to the charging cabinet 2 to carry out the normal charging step.

[0073] The normal charging step includes: S8. First, after the battery 1 after the charge-discharge to heat up the battery step is ended is left standing for 30 s, step S9 is executed.

[0074] S9. The charging cabinet 2 performs constant-current charging on the battery 1. During the constant-current charging, the charging current is 0.3C (mA), and the voltage is restricted. The constant-current charging time is 40 min, where "C" represents the rated capacity of the battery 1. The charging current of 0.3C (mA) means: the charging current is the rated capacity of the battery * 0.3 (mA).

[0075] In the step S9, the restricted voltage for the lithium iron phosphate battery is 3800 (mV), and the restricted voltage for the ternary battery is 4500 (mV).

[0076] S10. The charging cabinet 2 performs further constant-current charging on the battery 1. The charging current of this constant-current charging is 0.45C (mA), and the voltage is restricted. The charging time of this constant-current charging is 200 min, where "C" represents the rated capacity of the battery 1. The charging current of 0.45C (mA) means: the charging current is the rated capacity of the battery * 0.45 (mA).

[0077] In the step S10, the restricted voltage for the lithium iron phosphate battery is 3800 (mV), and the restricted voltage for the ternary battery is 4500 (mV).

[0078] S11. The charging cabinet 2 performs constant-voltage charging on the battery 1. The charging current of this constant-voltage charging is 0.45C (mA), and the voltage is restricted. The restricted current is 0.03C, and the charging ends, where "C" represents the rated capacity of the battery 1. The charging current of 0.45C (mA) means: the charging current is the rated capacity of the battery * 0.45 (mA).

[0079] With the above technical solution, the present invention is ingeniously conceived and applicable to use in a low-temperature environment of -15°C to 0°C. Moreover, it is convenient to use. It mainly utilizes the heat generation principle of lithium-ion batteries during charging and discharging, and performs shallow charge and discharge cyclically to automatically heat up the battery. This not only avoids the phenomenon of lithium deposition during charging of lithium-ion batteries under low-temperature conditions, but also does not affect the cycle life of lithium-ion batteries. Additionally, it can utilize the heat generated by the lithium-ion battery itself to increase the battery temperature. After the temperature reaches a certain value, it conducts conventional high-current discharge, which is convenient to use and saves the additional heater required to heat the battery, greatly reducing the production and use costs.

[0080] For those of ordinary skill in the art, according to the teachings of the present invention, without departing from the principles and spirit of the present invention, the changes, modifications, substitutions, and variations made to the embodiments still fall within the protection scope of the present invention.

Claims

1. A method for charging a lithium-ion battery in a low temperature environment, characterized in that: The method specifically comprises the steps of assembling a charging system, charging and discharging to raise the temperature of the battery, and a normal charging step; The steps of assembling the charging system include: S1. The charging system includes a charging cabinet and a management system. The management system includes a temperature detection device. The temperature detection line of the temperature detection device is connected to the battery. The management system obtains the surface temperature of the battery through the temperature detection device. The output end of the charging cabinet is connected to the positive and negative electrodes of the lithium-ion battery to be charged. S2, when the surface temperature of the battery detected by the management system is -20°C<T<0°C, charging and discharging are performed to increase the temperature of the battery; The steps of charging and discharging to increase the temperature of the battery include: S3, first let the battery stand for 2 seconds, then execute step S4; S4. The charging cabinet charges the battery with a constant current. The charging current of the constant current charging is 0.15-0.3C (mA) and the constant current charging time is 30-50s, where "C" represents the rated capacity of the battery. S5. After constant current charging is completed, the battery is left to stand for 2 seconds, and then step S6 is executed; S6. The charging cabinet discharges the battery at a constant current. The discharge current of the constant current discharge is 0.15-0.3C (mA) and the constant current discharge time is 40s, where "C" represents the rated capacity of the battery. Then, steps S4, S5, and S6 are repeated 100 times.

2. A method for charging a lithium-ion battery in a low temperature environment according to claim 1, characterized in that: In the step of heating the battery by charging and discharging, the management system detects the surface temperature of the battery in real time. When the surface temperature of the battery is lower than 5°C after the step of heating the battery by charging and discharging is completed, the step of heating the battery by charging and discharging is repeated until the surface temperature of the battery is higher than 5°C.

3. A method for charging a lithium-ion battery in a low temperature environment according to claim 2, characterized in that: The method further includes the following steps: S7, the management system detects the surface temperature of the battery in real time, and when the surface temperature of the battery is higher than 5°C, the charging and discharging step is terminated to warm up the battery, and a normal charging step is performed.

4. A method for charging a lithium-ion battery in a low temperature environment according to claim 3, characterized in that: In step S7, the management system detects the surface temperature of the battery in real time. When the surface temperature of the battery is higher than 5°C, the management system issues an instruction to the charging cabinet to end the charging and discharging process to warm up the battery. After the end, the management system issues an instruction to the charging cabinet to perform normal charging steps.

5. A method for charging a lithium-ion battery in a low temperature environment according to claim 4, characterized in that: The normal charging step specifically includes: S8, after the charging and discharging step to raise the battery temperature, the battery 1 is left to stand for 30 seconds, and then step S9 is executed; S9. The charging cabinet charges the battery with a constant current. The charging current is 0.15-0.3C (mA) and the voltage is limited. The constant current charging time is 40-60 minutes, where "C" represents the rated capacity of the battery. S10, the charging cabinet further performs constant current charging on the battery, the charging current of the constant current charging is 0.25~0.45C (mA), and the voltage is limited. The charging time of the constant current charging is 200min, where "C" represents the rated capacity of the battery; S11, the charging cabinet performs constant voltage charging on the battery, the charging current of the constant voltage charging is 0.25-0.45C, and the voltage is limited, wherein the limited current is 0.03C, and the charging is completed.

6. A method for charging a lithium-ion battery in a low temperature environment according to claim 5, characterized in that: In step S9, the voltage limit for the lithium iron battery is 3800 (mV), and the voltage limit for the ternary battery is 4500 (mV).

7. A method for charging a lithium-ion battery in a low temperature environment according to claim 6, characterized in that: In step S10, the voltage limit for the lithium iron battery is 3800 (mV), and the voltage limit for the ternary battery is 4500 (mV).

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