Why is the lithium battery capacity be lowered in winter?

ଲେଖକ: ଆଇଫ୍ଲୋପାୱାର - Zentral elektriko eramangarrien hornitzailea

Since entering the market, lithium-ion batteries has been widely used in their advantages of their long life, large specific capacity, no memory effect. Low temperature in lithium ion battery is low, severe attenuation, poor cycle magnification, and obvious lithium phenomenon, and deinterlaxing lithium imbalance. However, as the application is continuously expanding, the restriction of low temperature performance of lithium-ion batteries is increasing.

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

But in the fields of aerospace, electric vehicles, the battery can be required to work normally at -40 ¡ã C. Therefore, it is of great significance to improve the low temperature properties of lithium ion batteries Factors constrained lithium ion battery low temperature performance In a low temperature environment, 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 results in a solid state electrolyte interface (SEI) thickness increase Lithium ion batteries decrease in the internal diffusion system in the active substance under low temperature environment, and the charge transfer impedance (RCT) is significantly increased.

 Discussion on the decisive factors affecting low temperature performance of lithium ion batteries Expert perspective 1: The electrolyte affects the low temperature performance of lithium ion batteries, the composition and materialization properties of the electrolyte have an important impact on battery low temperature. The problem in the battery low temperature is: the viscosity of the electrolyte will be large, the ion conduction speed 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 delegra in 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 itself, and the transmission ion of the electrical conductivity is fast, and more capacity can be exhibited at low temperatures. The more lithium salts in the electrolyte, the more the number of migration is, the higher the conductivity. The speed of 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 electrolyte electrical conductivity is related to the compositional composition of the electrolyte, and the viscosity of the solvent is to improve the pathway of the 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 electrolyte is also a key to affecting lithium ion conductance, and RSEI is the main impedance of a lithium ion battery in a low temperature environment.

 Expert 2: Limiting the main factor in low temperature performance of lithium ion batteries is a sharp increase in LI + diffusion impedance at low temperatures, but not the SEI film.<000000>nb.