Lithium ion battery low-temperature electrolyte and lithium ion battery

Abstract

The invention discloses a lithium ion battery low-temperature electrolyte and a lithium ion battery. The lithium ion battery low-temperature electrolyte comprises 2%-20% of lithium salt, 0.01%-20% of a low-temperature additive, 0.1%-10% of a film-forming additive and 70%-90% of a non-aqueous organic solvent. The electrolyte provided by the invention has relatively high low-temperature conductivity, and can improve the cycle performance, the rate capability and the capacity retention ratio of the lithium ion battery at low temperature; at the same temperature of-50 DEG C, the electrolyte provided by the invention has lower viscosity and much higher conductivity than the conventional electrolyte, and the low-temperature cycle life of the lithium ion battery adopting the electrolyte can be prolonged by more than 20%.

Description

technical field [0001] The invention relates to the field of lithium batteries, in particular to a low-temperature electrolyte of a lithium ion battery and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in various fields due to their high energy density, long cycle life, no memory effect, and environmental friendliness. With the expansion of its application range, more stringent requirements are put forward for the performance of lithium-ion batteries. Especially in extremely cold application scenarios such as polar regions, deep seas, mountains, and space, the low-temperature performance of lithium-ion batteries is always challenged. The impact of low temperature on lithium-ion batteries is mainly that the viscosity of the electrolyte increases greatly at low temperatures, the conduction of lithium ions is slow, and the electron migration rate of the external circuit does not match. When the battery is charged, dendrites are eas...

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Problems solved by technology

In terms of material modification, it is mainly through doping, coating and other means to reduce the interface impedance, reduce the side reaction of the material and the electrolyte, increase the layer spacing of the material, increase the diffusion rate of Li+ in the bulk, and reduce the diffusion resistance of Li+; Reducing the particle size of the electrode material can shorten the Li+ transport path, increase the specific surface area of ​​the material, increase the wetting area of ​​the electrolyte, and improve the low-temperature performance of the battery, but the increase in the specific surface area of ​​the electrode material will increase the reactivity of the material, resulting in side reactions with the electrolyte Aggravate, affect the performance of the battery, and the modification of the material will increase the manufacturing cost of the material

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