Low-temperature and high-voltage Zn-based liquid metal batteries based on multiple redox mechanism

Liquid metal battery (LMB) has raised extensive interest in the field of large-scale energy storage applications . The Zn-based LMB composed of inexpensive Zn and low-temperature electrolyte have proven to be feasible and promising. However, the low voltage plateau and coulombic efficiency still limit their practical application. Here we demonstrate a simple design Zn-based LMB, which consists of Zn 5 Sn 5 alloy as negative electrode , Bi as positive electrode and ZnCl 2 –LiCl–KCl molten salt with lower zinc chloride content as electrolyte. The battery can stably operate at a low temperature of 375 °C and exhibit a flat and high voltage plateau of 0.8–0.9 V. A high coulombic efficiency of over 96% can be achieved by optimizing the composition of electrolyte. Sn is added to yield a liquid negative electrode, and then the problem of Zn dendrites can be avoided. In addition to Zn, both Sn and Bi participate in the redox reaction , which contributes to a multiple redox reaction mechanism. The Zn-based liquid metal batteries with low temperature and high voltage will be a prospective choice for large-scale energy storage.