Low-temperature lithium-ion battery

Abstract

The invention discloses a low-temperature lithium-ion battery. The low-temperature lithium-ion battery comprises a positive plate, a membrane, a negative plate and an electrolytic solution, wherein the positive plate comprises a ternary lithium nickel-cobalt manganate material, the ternary lithium nickel-cobalt manganate material is a composite material of an aggregate material and a quasi-monocrystalline material, and the median particle diameter of the aggregate material is smaller than the median particle diameter of the quasi-monocrystalline material; the negative plate comprises a carbonmaterial, the carbon material comprises synthetic graphite and natural graphite, and the synthetic graphite and the natural graphite are both carbon-coated secondary particles; and the electrolytic solution comprises a solvent, lithium salt and an additive, the solvent comprises EC, DEC, EMC and an auxiliary solvent, the solvent is a quaternary or above compound, the lithium salt comprises LiPF<6>, LiFSI and LiPO<2>F<2>, and the additive comprises VEC, DTD and GBL. The low-temperature lithium-ion battery has good charge / discharge properties, high safety and high energy density under low temperature and can be well suitable for a low-temperature environment.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to low-temperature lithium-ion batteries. Background technique [0002] Lithium-ion batteries have the advantages of high specific capacity, long cycle life, low self-discharge rate, no memory effect, and environmental friendliness, and have broad application prospects in power batteries for electric vehicles. The working temperature of lithium-ion batteries is generally from minus 20°C to minus 60°C. At lower temperatures, such as minus 40°C, the charging and discharging performance of the battery is poor, the battery is difficult to charge, and the discharge capacity is only 12% of that at room temperature. , the energy density is low, and it is easy to precipitate lithium on the surface of the negative electrode, which has a high potential safety hazard. The main reasons for the poor low-temperature performance of lithium-ion batteries are as follows: (1) Under low...

AI Technical Summary

Problems solved by technology

The working temperature of lithium-ion batteries is generally from minus 20°C to minus 60°C. At lower temperatures, such as minus 40°C, the charging and discharging performance of the battery is poor, the battery is difficult to charge, and the discharge capacity is only 12% of that at room temperature. , the energy density is low, it is easy to precipitate lithium on the surface of the negative electrode, and there is a high potential safety hazard

The main reasons for the poor low-temperature performance of lithium-ion batteries are as follows: (1) Under low-temperature conditions, part of the solvent in the battery electrolyte solidifies, and the viscosity increases, resulting in difficulty in ion migration and low conductivity; (2) Under low-temperature conditions, in The transfer resistance of lithium in the electrode material is large; (3) under low temperature conditions, the lithium diffusion and charge transfer between the electrode and the electrolyte interface are slow; poor penetration

The performance of lithium-ion batteries at low temperature is poor, which seriously affects their application in low-temperature environments. Therefore, it is urgent to improve the low-temperature performance of lithium-ion batteries so that lithium-ion batteries have good performance at low temperatures. Better for low temperature environment

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