Performance of electrolyte with dimethyl methyl phosphonate as flame-retardant additive

To improve the safety of lithium-ion batteries, dimethyl additive in a LiPF6 electrolyte solution. The flammability and thermal methyl phosphonate（DMMP） was used as a flame-retardant stability of DMMP-containing electrolyte was investigated by means of burning test and accelerating rate calorimeter. It was found that the flammability and self-heat rate of the electrolyte can be reduced by the addition of DMMP. On the other hand, the electrochemical performances of graphite/LiCoO2 cells become slightly worse after using DMMP additive in the electrolyte. This alleviated trade-off between electrolyte flammability, thermal stability, and cell performance provides a possibility to formulate a nonflammable electrolyte containing DMMP and improve the electrolyte thermal stability with a minimal sacrifice in performance.