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Methods for improving low-temperature performance of lithium-ion batteries(1)

2024-06-05

Lithium-ion batteries have been widely used in consumer electronics, electric vehicles, energy storage and other fields due to their high specific energy and power density, long cycle life, and environmental friendliness. As the power source of new energy vehicles, lithium-ion batteries still have many problems in practical applications, such as the energy density is significantly reduced under low temperature conditions, and the cycle life is also affected accordingly, which also seriously limits the large-scale use of lithium-ion batteries.

At present, researchers are still debating the main factors that cause the poor low-temperature performance of lithium-ion batteries, but the reasons are as follows:

1. At low temperature, the viscosity of the electrolyte increases and the conductivity decreases.

2. The impedance of the electrolyte/electrode interface film and the charge transfer impedance increase;

3. The migration rate of lithium ions in the active substance body decreases. As a result, the polarization of the electrode is intensified at low temperatures, and the charge-discharge capacity is reduced.

this paper, the main influencing factors of low-temperature performance of lithium-ion batteries are systematically discussed from three aspects: cathode materials, electrolytes and anode materials, and effective methods to improve the low-temperature performance of lithium-ion batteries are proposed.

The main ways to improve the ion diffusion performance of cathode materials at low temperature are:

1. The method of surface coating of the active material body with excellent conductivity is used to improve the conductivity of the interface of the cathode material, reduce the interface impedance, and reduce the side reactions of the cathode material and the electrolyte, so as to stabilize the material structure.

2. The bulk phase doping of the material body is carried out by Mn, Al, Cr, Mg, F and other elements, and the layer spacing of the material is increased to increase the diffusion rate of Li in the body, reduce the diffusion impedance of Li, and then improve the low-temperature performance of the battery.

3. Reduce the particle size of the material and shorten the Li migration path. It should be noted that this method will increase the specific surface area of the material and thus increase the side reaction with the electrolyte.