Amorphous TiO2 shells: an Essential Elastic Buffer Layer for High-Performance Self-Healing Eutectic GaSn Nano-Droplet Room-Temperature Liquid Metal Battery

Gallium-based alloy liquid metal batteries currently face limitations such as volume expansion, unstable solid electrolyte interface (SEI) film and substantial capacity decay. In this study, amorphous titanium dioxide is used to coat eutectic GaSn nanodroplets (eGaSn NDs) to construct the core-shell structure of eGaSn@TiO2 nanodroplets (eGaSn@TiO2 NDs). The amorphous TiO2 shell (similar to 6.5 nm) formed a stable SEI film, alleviated the volume expansion, and provided electron/ion transport channels to achieve excellent cycling performance and high specific capacity. The resulting eGaSn@TiO2 NDs exhibited high capacities of 580, 540, 515, 485, 456 and 426 mAhg(-1) at 0.1, 0.2, 0.5, 1, 2 and 5 C, respectively. No significant decay was observed after more than 500 cycles with a capacity of 455 mAhg(-1) at 1 C. In situ X-ray diffraction (in situ XRD) was used to explore the lithiation mechanism of the eGaSn negative electrode during discharge. This study elucidates the design of advanced liquid alloy-based negative electrode materials for high-performance liquid metal batteries (LMBs).