Phosphorus-containing fire retardant additive of electrolyte for lithium-iron-phosphate batteries

Abstract

The invention discloses fire retardant electrolyte suitable for lithium-iron-phosphate batteries. The fire retardant electrolyte is characterized in that a phosphorus-containing compound is added into an ordinary electrolyte for lithium ion batteries, wherein the addition quantity of the phosphorus-containing compound is 1wt%-20wt% of the weight of the electrolyte for the lithium ion batteries. The phosphorus-containing compound dissolves in the electrolyte for the lithium ion batteries, the cycle performance of the batteries is not influenced, the phosphorus-containing compound does not participate in an electrochemical reaction of positive pole surfaces and negative pole surfaces, the combustibility of the electrolyte can be greatly reduced, and the production safety and the using safety of the lithium-iron-phosphate batteries are improved.

Description

technical field [0001] The invention relates to an electrolyte in a lithium iron phosphate battery, in particular to a class of phosphorus-containing flame retardant additives that can be used to improve the safety performance of the lithium iron phosphate battery and reduce the flammability of the electrolyte. Background technique [0002] Lithium iron phosphate material has excellent cycle life and safety performance due to its stable material structure. Lithium iron phosphate battery has also been widely used in the fields of energy storage batteries and automobile batteries. An important reason restricting the rapid development of electric vehicles is the safety performance of lithium-ion batteries. Although the safety of lithium iron phosphate batteries is better than that of ternary and lithium manganese oxide batteries, there are still potential safety hazards in large-capacity batteries, especially in the case of fire under abuse (such as thermal shock, overcharge, o...

AI Technical Summary

Problems solved by technology

The research on the application of flame retardants in lithium-ion battery electrolytes has received widespread attention at home and abroad. The research on phosphorus-containing organic compounds is the earliest, and related patent reports have been published (Patent No. 200510024433.1). Although these phosphorus-containing compounds have certain Flame retardancy, but the reduction and decomposition reaction will occur on the graphite negative electrode during the first charging and discharging process of the battery, which will greatly reduce the cycle performance of the battery, and more flame retardants need to be added to achieve the flame retardant effect. The electrolyte often Due to its addition, the viscosity will increase, the conductivity will decrease, and the wettability will deteriorate

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