Novel high phosphorus content phosphaphenanthrene-based efficient flame retardant additives for lithium-ion battery

The novel phosphate derivatives of phosphaphenanthrene with high-density phosphorus were synthesized and used as flame retardant additives for Li-ion batteries. The structures of compounds were characterized by H-1 NMR, C-13 NMR, P-31 NMR, FT-IR, and HR-MS. The excellent thermal stability of compounds was ascertained by thermogravimetric analysis and differential scanning calorimetry. The compounds were added to conventional electrolytes as flame retardant additives and evaluated their ionic conductivity, electrochemical stability, self-extinguishing properties, and combustion performance. The results showed that the compound containing higher phosphorus content has efficient flame retardant properties.