LITHIUM ION BATTERY ELECTROLYTE ADDITIVE

The present disclosure relates to a phosphorus additive that is useful for stable cycling and storage of lithium ion cells at high temperatures, an electrolyte containing the phosphorus additive, and an electrochemical energy storage device containing the electrolyte. An electrolyte includes an aprotic organic solvent system; a metal salt; and at least one thiophosphate additive having a nitrile terminal group, according to the formula: