High-Performance Antimony–Bismuth–Tin Positive Electrode for Liquid Metal Battery

The liquid metal battery (LMB) is an attractive chemistry for grid-scale energy-storage applications. The full-liquid feature significantly reduces the interface resistance between electrode and electrolyte, endowing LMB with attractive kinetics and transport properties. Achieving a high energy density still remains a big challenge. Herein, we report a low-melting-point antimony–bismuth-tin positive electrode for LMB with high energy density and excellent rate performance for the first time. The electromotive force of Li||Sb–Bi–Sn system is determined by Li||Sb and Li||Bi chemistries. The Sn component plays a bifunctional role in the chemistry, decreasing the melting point of Sb–Bi–Sn alloy and providing rapid lithium diffusion paths for the electrode reaction. The ternary feature of the positive electrode ensures a low Sn concentration for the eutectic requirement of the positive electrode working at moderate temperature (500 °C). The stepwise reaction characteristics of Sb and Bi provides a dynamic microstructure change of intermediate compounds during the charge/discharge process, allowing the electrolyte to penetrate and make contact with the positive electrode to enable a fast electrode reaction. A synergetic combination of these advantages enables the reported Sb–Bi–Sn electrode to demonstrate a high energy density of about 260 Wh kg –1 and excellent rate capability with almost no capacity degradation at different current densities from 200 to 1200 mA cm –2 . All these excellent properties demonstrate that the Sb–Bi–Sn alloy is an ideal positive electrode of LMB for large-scale applications.