Low-temperature electrolyte of lithium iron phosphate power battery and preparation method thereof

Abstract

The invention provides a low-temperature electrolyte of lithium iron phosphate power battery and a preparation method thereof, and belongs to the technical field of lithium iron phosphate power batteries. The low-temperature electrolyte of the lithium iron phosphate power battery is prepared from 65 to 95 percent of organic solvent, 3 to 15 percent of additive and 0.7 to 1.4 mol / L of lithium salt. The preparation method comprises the following steps of: fully and uniformly mixing one or more selected organic solvents in a glove box at the humidity of below 1 percent for preparing electrolyte solution; adding the selected additive into the solution; finally adding the required lithium electrolyte salts into the solution; and when all the added lithium electrolyte salts are fully dissolved, standing for 30 to 40 hours to obtain the low-temperature electrolyte of the lithium iron phosphate power battery. The low-temperature electrolyte of the lithium iron phosphate power battery of the invention has the advantages of suitability for a low-temperature environment, rational component selection and matching, good low-temperature charging-discharging performance, magnification performance and cycling performance, simple preparation method and easy operation.

Description

(1) Technical field [0001] The invention relates to a lithium iron phosphate power battery technology, in particular to a low-temperature electrolyte for a lithium iron phosphate power battery and a preparation method thereof. (2) Technical background [0002] The contemporary development of electric vehicles is the best way to solve the energy crisis and environmental pollution. In recent years, electric vehicles have developed rapidly, and various types of electric vehicles have emerged. Among the three commonly used vehicle batteries, lead-acid batteries have basically withdrawn from mainstream applications due to low specific energy, poor cycle performance, and certain environmental pollution; although nickel-metal hydride batteries are currently the mainstream of commercialization, their main indicators are lower than those of phosphoric acid. Lithium iron battery, and theoretically there is basically no room for improvement. Lithium iron phosphate power battery has t...

AI Technical Summary

Problems solved by technology

However, there is still a bottleneck problem to be solved in the charge and discharge of lithium iron phosphate batteries under low temperature conditions; besides the positive material, the electrolyte is one of the most important factors for the low temperature performance of lithium iron phosphate power batteries. At this stage, the electrolyte of lithium iron phosphate power batteries is mainly If it is composed of carbonate solvents, such as ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate (PC), etc., but Any solvent has its own advantages and disadvantages. At present, the electrolyte solvent is composed of several solvents mixed together in a certain proportion. Therefore, the selection of solvent components and the ratio between components are the key to optimize the electrolyte.

[0003] At this stage, the discharge capacity of lithium iron phosphate power battery electrolyte at -20°C is only about 50% of that at 25°C, and it can hardly discharge electricity at -40°C. It is very difficult to use electric bicycles and electric vehicles in winter in the north , thus greatly limiting the application of lithium iron phosphate power batteries

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