An elaborate low-temperature electrolyte design towards high-performance liquid metal battery

Liquid metal battery (LMB) with low cost, excellent cycle performance and flexible scalability is developed as a promising solution for large-scale energy storage. However, the high melting point of the electrolyte necessitates an elevated operating temperature, which provokes aggravated hermetic seal and corrosion issues, seriously inhibiting the advancement of LMBs. Herein, we elaborately design a novel LiCl–LiBr–KBr electrolyte system based on the mass triangle model to overcome this obstacle. The LiCl and LiBr components can provide required lithium ionic conduction, while the KBr plays a dual role of decreasing the melting point and suppressing metal lithium dissolution. The designed LiCl–LiBr–KBr (33:29:38 mol%) electrolyte possesses low melting point (Tm = 327 °C), and high ionic conductivity (1.573 S cm−1 at 420 °C), which enables the Li||Bi battery to work efficiently at 420 °C with high energy efficiency (83%), excellent rate capability, superior cycling stability and freeze/thaw performance. This represents an 80–130 °C decrease in operating temperature compared to most reported LMBs. The unique performance combination together with its low cost makes the designed electrolyte extremely attractive for low-temperature LMB.