Room-Temperature Rechargeable Ca-Ion Based Hybrid Batteries with High Rate Capability and Long-Term Cycling Life

Calcium-ion batteries (CIBs) are promising energy storage devices due to the merits of natural abundance, similar standard reduction potential to lithium, and bivalent-ion characteristic of calcium. However, the development of CIBs is hindered by the low rate capability and poor cycling performance at room temperature. Here, a highly reversible room-temperature calcium-ion based hybrid battery is realized by a tri-ion strategy, which significantly improves the diffusion kinetics of calcium ions. The optimized CIB shows high rate capability of 15 C as well as excellent cycling stability over 1500 cycles with 86% capacity retention at 5 C, at room temperature, which is the best result of reported calcium-ion based full batteries.