Enabling high reversible capacity of Ca metal batteries at 50 °C via thermally stable electrolytes

Stable operation of Ca metal batteries at elevated temperatures is significantly limited by electrolyte volatility. In this study, a low-volatility Ca(CB 11 H 12 ) 2 /diglyme electrolyte with CaBr 2 enables stable Ca plating/stripping at 50 °C. In contrast to conventional volatile ether-based systems, this thermally stable electrolyte facilitates near-theoretical capacity utilization in NaTi 2 (PO 4 ) 3 cathodes, overcoming the kinetic limitations typically observed at room temperature. • Ca(CB 11 H 12 ) 2 /G 2 with CaBr 2 electrolyte enables stable Ca plating/stripping at 50 °C. • Inorganic-rich interphase enables stable Ca metal cycling at 50 °C. • Low volatility is attributed to the high-boiling point of G2 solvent. • Stable 50 °C operation enables near-theoretical Ca storage in NaTi 2 (PO 4 ) 3 .