High-rate electrolyte of lithium iron phosphate power battery and preparation method thereof and battery

Abstract

The invention discloses a high-rate electrolyte of a lithium iron phosphate power battery and a preparation method thereof and the battery. The battery comprises lithium salt and an organic solvent, wherein the organic solvent comprises 90 wt%-95 wt% of a non-aqueous organic solvent and 5 wt%-10 wt% of a functional additive, the non-aqueous organic solvent comprises ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, the functional additive comprises vinylene carbonate, 1, 3-propane sultone, fluoroethylene carbonate and acetonitrile, and the electrolyte is suitable for the powerbattery with the multiplying power not lower than 6C lithium iron phosphate. According to the battery provided by the invention, the capacity of the battery is kept at 95.6% after 900 times of 3C charge-discharge cycles, the capacity of the battery is kept at 87% after 1000 times of 6C cycles, and the rate cycle performance of the battery is greatly improved.

Description

【Technical field】 [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a high-rate electrolyte for a lithium iron phosphate power battery, a preparation method, and a battery. 【Background technique】 [0002] Lithium iron phosphate batteries are superior to other types of batteries in terms of electrochemical performance, including reversible capacity, stability, safety, cyclicity and high current discharge capacity, and the price of raw materials. The capacity retention rate of lithium iron phosphate battery can still reach more than 80% after 1C cycle of 2000 times, and the cycle performance is much higher than that of lithium cobaltate, ternary materials and lithium manganate. However, with the development and changes of the market, people have also put forward high requirements for lithium-ion batteries, that is, high specific power, fast charging and deep discharge, which have become the mainstream direction of lithiu...

AI Technical Summary

Problems solved by technology

[0003] In the normal temperature range, on the one hand, the electron movement speed is very fast when the lithium iron phosphate battery is discharged with a large current, and on the other hand, because the conductivity of the lithium iron phosphate battery electrolyte is only one percent of the aqueous solution, so Li + The transfer rate of the lithium iron phosphate battery is very low, so the lithium iron phosphate battery will be polarized, and then the lithium iron phosphate battery will be limited in high rate cycle applications

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