What is the cause of lithium battery capacity?

　　Author ：Iflowpower – Portable Power Station Supplier

According to reports, the discharge capacity of the lithium-ion battery is only about 31.5% at room temperature at -20 ¡ã C. Traditional lithium-ion battery operating temperature between -20 ~ + 55 ¡ã C.

But in the category of aerospace, electric vehicles, require the battery to work properly at -40 ¡ã C. Therefore, it is of great significance to improve the low temperature properties of lithium ion batteries. In low temperature environments, the viscosity of the electrolyte increases, even partially solidified, resulting in a low-conductivity of the lithium ion battery.

The compatibility between the electrolyte and the negative electrode and the diaphragm is deteriorated in a low temperature environment. The negative electrode of the lithium ion battery under low temperature environments was severely precipitated, and the precipitated metal lithium was reacted with an electrolyte, and the product deposition caused to a solid electrolyte interface (SEI) thickness. Lithium-ion batteries under low temperature environment reduce the internal diffusion system of the active substance, the charge transfer impedance (RCT) is significantly increased.

Expert perspective 1: Electrolyne solution affects the low temperature performance of lithium ion batteries, the composition and materialization properties of electrolyte have a negative effect on battery low temperature performance. The problem in the surface of the battery is: the viscosity of the electrolyte will become large, the ion conductivity is slow, resulting in the electron migration speed of the external circuit, so the battery has severely polarized, and the charge and discharge capacity has a sharp decrease. Especially when low-temperature charging, lithium ions can easily form lithium delegranes on the surface of the negative electrode, resulting in failure of the battery.

The low temperature performance of the electrolyte is closely related to the size of the electrolyte own conductivity, the transmission ion of the electrical conductivity is fast, and more capacity can be exerted at low temperatures. The more lithium salts in the electrolyte, the more the number of migrations, the higher the conductivity. High electrical conductivity, the faster the ion conductivity, the smaller the polarization, the better the performance of the battery at low temperature.

Therefore, higher conductivity is a necessary condition for achieving good low temperature performance of lithium ion batteries. The electrical conductivity of the electrolyte is related to the composition of the electrolyte, and the viscosity of the solvent is to improve the pathway of electrolyte electrical conductivity. The fluidity of solvent is good at a low temperature of the solvent is the guarantee of ion transport, and the solid electrolyte membrane formed by the electrolyte in the low temperature is also a key to affecting lithium ion conductance, and RSEI is a tight impedance of a lithium ion battery in a low temperature environment.

Expert 2: Taste factors to limit low temperature performance of lithium ion batteries are low temperatures, new Li + diffusion impedance, but not SEI film. The layered structure has both a one-dimensional lithium-ion diffusion channel, which has a three-dimensional channel structure stability, and is the first commercial lithium ion battery positive material. Its representative substances include LiCoO2, Li (CO1-XNIX) O2 and Li (Ni, Co, Mn) O2, e.