Low-Temperature and High-Energy-Density Li-Based Liquid Metal Batteries Based on LiCl–KCl Molten Salt Electrolyte

Li-based liquid metal batteries (LMBs) have attracted widespread attention due to their potential applications in sustainable energy storage; however, the high operating temperature limits their practical applications. Herein, a new chemistry─LiCl–KCl electrolyte and Sb–Bi–Sn (Pb) positive electrode─is reported to lower the operating temperature of Li-based LMBs and achieve a high energy density. We have investigated the compatibility between low-melting-point LiCl–KCl molten salt and Li and found that the displacement reaction between LiCl–KCl and Li would decrease the KCl content. Addition of a small amount of K to Li can inhibit this displacement reaction and maintain the stability of the molten salt composition, thereby significantly improving the cycling stability of the batteries at a low operating temperature (400 °C). Specifically, the LiK|LiCl–KCl|Sb30Bi40Sn30 LMB exhibits a high energy density of about 241 W h kg–1 and a low material cost of about 68.8 $ kW h–1. Besides, the energy density of the LiK|LiCl–KCl|Sb30Bi40Pb30 LMB is about 194 W h kg–1, which has a lower material cost of about 62.8 $ kW h–1. We propose that this work can open new directions toward designing and developing innovative LMBs for sustainable energy storage.