Improving Wettability at Positive Electrodes to Enhance the Cycling Stability of Bi-Based Liquid Metal Batteries

Liquid metal batteries (LMBs) are promising candidates for grid-scale energy storage due to their exceptional kinetics, scalability, and long lifespan derived from the distinctive three-liquid-layer structure. However, the positive electrode (such as Bi) suffers from insufficient wettability on the current collector, resulting in excess electrical resistance and uneven current distribution, thus deteriorating the cycling stability. Here the incorporation of 4 mol% Se into Bi-based metal is proposed producing an interface layer with highly surface-active property that decreases the electrode's contact angle with the 304 stainless-steel (SUS304) from 144.7 degrees to 74.3 degrees, so as to improve the wettability. The as-prepared 20 Ah Li || Bi-Se4 (the content of Se is 4 mol% of Bi) cell cycled 1200 times with capacity fade rate of merely 0.00174% per cycle. This facile and effective approach provides a pathway toward the production of stable cells with an extended lifespan and boosts the practical implementation of LMBs. To enhance the wettability of the Bi-based positive metal on the current collector in liquid metal batteries, the highly surface-active element Se as an additive is employed to decrease the surface tension. The obtained Bi-Se4 positive electrode exhibits superior cycle performance with only 2.1% capacity decay during 1200 cycles thanks to the more stable interface with the electrolyte. image