Study On Fire Hazard Of Electrolytes Of Lithium Ion Batteries Based On Cone Calorimeter

Lithium-ion batteries generally use flammable carbonates at high temperatures as electrolyte solvents,which have a high risk of fire.Therefore,research on the fire hazard of lithium-ion battery electrolytes is of great significance for the prevention of lithium-ion battery fires.To this end,this paper uses conical calorimeter as the main research method,analyzes the combustion characteristics of common lithium ion battery electrolyte solvent,and discusses the effects of solute,cathode material and flame retardant additive on its combustion characteristics.On this basis,the fire risk of lithium-ion battery electrolyte was evaluated by means of fire hazard composite index?IFHI?and flash fire characteristics index.The test results of the solvent of a single lithium ion battery electrolyte show that the peak value of the total exotherm and heat release rate of the cyclic carbonate is significantly lower than that of the chain carbonate,and the ethylene carbonate?EC?is the lowest.The test results of the binary or ternary mixed solvent formed by compounding several solvents show that the cyclic carbonate can suppress the peak rate of the thermal release rate of the chain carbonate,but increase the risk of fire.The effects of LiPF₆ solute and typical positive electrode materials on the combustion characteristics of lithium ion battery electrolyte solvent were investigated.The results show that the addition of LiPF₆ solute increases the heat release rate and total heat release of the electrolyte,while the positive electrode material coexists with the electrolyte.At the time,the thermal reaction of the electrolyte is accelerated and the heat release rate and total heat release amount are increased.Based on the cone calorimeter test data,the fire hazard composite index?IFHI?and flash fire characteristics index were used to evaluate the fire hazard of lithium ion battery electrolyte.The results show that the lithium ion battery electrolyte fire risk Higher,and the risk of fire increases with the addition of LiPF6 and the positive electrode material.At the end of the paper,several typical flame retardant additives such as triethyl carbonate?TEP?,dimethyl methylphosphonate?DMMP?,methyl difluoroacetate?MFA?and bis?2,2,2-trifluoroethyl?were selected.Ethyl phosphate?TDP?,its effect on the combustion performance of lithium ion battery electrolyte was investigated.The test results show that the flame retardant additive can significantly reduce the heat release rate and total heat release of the lithium ion battery electrolyte.However,the results of fire hazard composite index?IFHI?and flash fire characteristics index indicate:electrolyte fire risk>adding a single flame retardant additive electrolyte fire risk>adding compound flame retardant additive electrolyte fire risk.Further comparison with the corresponding indices of several representative substances?ethanol,kerosene,ethylene glycol?in different fire hazard categories indicates that the fire hazard of lithium ion battery electrolytes with these flame retardant additives is still close to that of B.Classes still have a high fire risk.