Achieving superior electrode kinetics in bismuth-based liquid metal batteries via tin additive

Liquid metal battery (LMB) is emerging as a promising solution for grid-scale energy storage, offering advantages such as low cost, long lifespan, safety, ease of configuration and scalability. However, the discharge products, consisting of solid intermetallic compounds with dense structure, suffer from insufficient ion transport, leading to high polarization and unsatisfactory rate performance. In this study, we address this challenge by implementing an alloy cathode with a networked structure formed by liquid tin (Sn), which enhances electrochemical kinetics. Notably, the bismuth-tin (Bi-Sn) alloy cathode exhibits a significantly high lithium (Li) ion diffusion coefficient, reducing polarization voltage and increasing the reaction stoichiometric ratio of Li. The Li||Bi-Sn cell achieves a high energy efficiency of 91.39 %, with enhanced material utilization of 93.91 % at 100 mA cm⁻². Additionally, it demonstrates excellent high-rate capability, with 81.87 % of capacity retention and 64.86 % of energy efficiency at 600 mA cm⁻² (3.40 C). These exceptional performance metrics, combined with a competitive cost of 88.69 $ kWh⁻¹, make the Li||Bi-Sn cell a highly attractive candidate for large-scale energy storage applications.