Lithium iron phosphate power battery with improved low temperature charge performance

Abstract

The invention discloses a lithium iron phosphate power battery with an improved low temperature charge performance, belongs to the technical field of lithium iron phosphate power batteries, and aims to solve the problem that the negative pole can easily reach a cut-off voltage, and the charge capacity is reduced therefore. The lithium iron phosphate power battery is characterized by comprising a positive plate, a negative plate, and electrolyte. The lithium salt is lithium hexafluorophosphate (11.5-15.0%). The organic solvent is a four component mixed solvent, which is composed of propylene carbonate, methyl carbonate, ethyl carbonate, and diethyl carbonate according to a ratio of 10-40: 1-10: 20-50: 10-30. The additive is one or more of vinylene carbonate, fluoroethylene carbonate, propargyl sulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, and lithium tetrafluoro(oxalato)phosphate. The interface impedance of the negative pole can be reduced, the low temperature properties of the lithium iron phosphate power battery are obviously improved, and the low temperature charge performance of the lithium iron phosphate power battery is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium iron phosphate power batteries, and in particular relates to a lithium iron phosphate power battery capable of improving low-temperature charging performance. Background technique [0002] Lithium iron phosphate power battery has the advantages of high safety, long cycle life, environmental friendliness, non-toxic and harmless, and relatively low cost, so it has attracted widespread attention and has been widely used in electric vehicles. However, because the lithium intercalation potential of the graphite negative electrode is 0.1 volts, which is very close to zero volts, charging at low temperature, because the polarization increases, the negative electrode is easy to reach the cut-off voltage ahead of time, resulting in a decrease in charging capacity. In severe cases, the potential of the negative electrode is even lower than zero volts. Lithium dendrites are precipitated on the surface of the...

AI Technical Summary

Problems solved by technology

[0006] However, softening, hard carbon or reducing the degree of graphitization and reducing the particle size all reduce the effective capacity of the negative electrode. Therefore, the above methods all improve the low-temperature charging performance under the premise of sacrificing the energy density of the battery to a certain extent.

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