Ternary intermediate phase mediated high energy density and kinetically accelerated Sb-Cd electrode for liquid metal batteries

Liquid metal battery (LMB) is an attractive technology that can address the big challenge of efficient utilization of renewable energies, ascribed to its potential ultralong service lifetime, ideal cost-efficiency, and high safety. However, breaking through the energy density bottleneck remains a persistent challenge, due to the limited lithiation voltage and specific capacity of cathodes. Herein, we design a novel dual-active Sb-Cd cathode, which shows a new ternary alloying discharge mechanism with reversible formation of ternary intermediate phase LiCdSb, accompanied by a high discharge voltage of 1.0 V. Coupled with the excellent Li storage capability of Cd, the Sb80Cd20 cathode attains an attractive capacity (> 500 mAh g(-1)), outperforming all reported LMB cathodes. More importantly, upon deep lithiation, the conversion reaction of ternary LiCdSb to Li3Sb mediates the regeneration and dispersion of Cd melt in the cathode, which constructs in situ fast electron and lithium diffusion networks for the subsequent discharge, significantly accelerating the electrode reaction kinetics. Thus, the Sb80Cd20 electrode achieves an exceptional combination of high energy density (398.4 Wh kg(-1) at 200 mA cm(-2)) and superior rate capability (542.5 W kg(-1) at 2400 mA cm(-2)). Additionally, the Li||Sb-Cd battery exhibits an outstanding tolerance and self-healing ability towards thermal runaway.