Why winter lithium battery capacity will fall?

Source: 2020 - 03 - 23 now hits: why winter lithium battery capacity will fall? Since listing, lithium ion batteries due to its long service life, large specific capacity, the advantages of no recall effect has been widely used. Lithium-ion batteries used in low temperature in the low capacity, the serious attenuation, loop is clearly worse than function, lithium disconnect, lithium disconnect imbalance and other issues. However, with the expansion of the application domain, the lithium ion battery low temperature performance of low quality more apparent. It is reported that the lithium ion battery in - 20 ℃ when the discharge capacity is only 31 at room temperature. About 5%. Working temperature in - traditional lithium-ion batteries Between 20 ℃ and + 55 ℃. However, in areas such as aerospace, military, electric vehicles, battery needs to be in - Under 40 ℃ to work properly. As a result, improve the low temperature performance of lithium-ion batteries is of great significance. The performance factors in the lithium ion battery at low temperature under low temperature, the viscosity of the electrolyte increases, some even condensation, resulting in a decline in lithium ion battery electric conductivity. Low temperature, electrolyte and cathode, the compatibility of the diaphragm. Low temperature, the lithium ion battery cathode precipitation, precipitation of metallic lithium lithium ions react with the electrolyte, product buildup of solid electrolyte interface ( SEI) Thickness increases. Low temperature, the charge transfer impedance of the lithium ion battery ( 个随机对照试验) With the decrease of the dispersion system in the active material and significantly increased. Why winter lithium battery capacity will fall? Affect the decisive factor of the lithium ion battery low temperature performance expert opinion 1: electrolyte for lithium ion battery had the greatest influence function at low temperature. Composition and physical and chemical properties of electrolyte had important effect on the low temperature performance of the battery. Under low temperature, the cell cycle will face the following problems: the electrolyte viscosity increases, ionic conduction slow, lead to external electronic removal rate mismatch, make the battery polarization is serious, a sharp drop in charge and discharge capacity. Especially in the low temperature charging, lithium ion in anode surface lithium dendrite formation, lead to battery failure. The low temperature of electrolyte function is closely related to the size of the electrical conductivity of electrolyte itself. High conductivity of the electrolyte ion transport speed, can play a greater capacity in low temperature. The lithium ions in the electrolyte solution is, the more the higher the removal rate of lithium ion, lithium ion conductivity is higher. The higher the conductivity, the faster the ionic conduction velocity, the smaller the polarization, the better the performance of battery low temperature. Therefore, high electric conductivity is a necessary condition for the lithium ion battery good low temperature performance of. The electrical conductivity of electrolyte is associated with the composition of the electrolyte. Reduce the solvent viscosity is one of the ways to improve the electrolyte conductivity. Excellent solvent at low temperature of liquid is to ensure that the ion transport and solid electrolyte membrane electrolyte at low temperature formation of the negative electrode is a key to lithium ionic conduction and rsei were the main the impedance of the lithium ion battery in low temperature environment. Experts 2: the main factors restricting the low temperature performance of lithium-ion batteries is the lithium ion battery at low temperature lithium ion diffusion impedance increases sharply, rather than the SEI.