Formation of thermally resistant films induced by vinylene carbonate additive on a hard carbon anode for lithium ion batteries at elevated temperature

Vinylene carbonate (VC)-induced film formation in a LiFePO₄/hard carbon (HC) cell is clarified based on mass spectroscopic analysis. VC is found to induce the formation of different types of thermally resistant organophosphates on the HC surface for different solvents and their formation mechanisms are elucidated. Formation of the organophosphates is also found to contribute to the improved cycle performance at elevated temperature due to their thermally stable characteristics.