Enroute to sub-300 °C operating Sn–Zn||Pb–Bi liquid metal battery by compositional engineering

Abstract

Liquid metal battery (LMB) is considered a potential contender for grid-scale energy storage systems. However, high operating temperatures (>400 °C) leading to higher operational costs limit its commercial application. Therefore, the current work focuses on reducing the melting temperature of electrodes and electrolytes below 300 °C by compositional engineering. Moreover, this study utilizes earth-abundant elements like Zn (with less reliance on Li), in Zn–Sn||Bi–Pb LMB system. The composition of LiCl in the electrolyte is varied to optimize the battery performance, especially the energy efficiency and overpotential while maintaining an operating temperature of <275 °C. It is found that as the LiCl content in the electrolyte salt increases (5–30 Mol%), the overpotential of the battery decreases (0.9–0.3 V), and the energy efficiency of the charge-discharge process improves (14.5%–80.9%) owing to the better ionic conductivity of LiCl. For the optimized LiCl concentration of 30 Mol% LiCl in the electrolyte, the fabricated LMB exhibit good cyclability (no degradation till 100 cycles), a high discharging voltage plateau of 0.92 V, 24.6 mAh charge storage capacity, and a low operating temperature of 275 °C, which is the lowest operating temperature reported so far in a Zn-based LMB system.