Hierarchical-Structured RGO@EGaIn Composites as Advanced Self-Healing Anode for Room-Temperature Liquid Metal Battery.

Gallium-based liquid metal (LM) has emerged as a promising candidate anode material for lithium-ion batteries (LIBs), exhibiting high theoretical capacity, excellent electrode kinetics, and unique self-healing ability. However, the liquid-solid-liquid transition during the electrochemical reactions can disrupt the solid electrolyte interphase (SEI) and damage the structural integrity, ultimately limiting the cycling stability. Here, hierarchical-structured reduced graphene oxide coated eutectic gallium-indium liquid metal particles (RGO@EGaIn LMPs) are synthesized using a facile self-assembly strategy. The customized RGO@EGaIn electrode demonstrated impressive performance in both half-cell and full-cell configurations for LIBs. The morphological and phase transitions of RGO@EGaIn LMPs during the lithiation/delithiation processes are uncovered by real-time in situ transmission electron microscopy tests. It is clarified that the presence of RGO in the hierarchical structure buffers the volume expansion of LMPs from ≈160% to 125% and provides a fast pathway for the rapid transfer of ions and electrons during the electrochemical reaction, which effectively enhances the electrochemical performance of the electrode. This work introduces a straightforward and effective method for preparing high-performance room-temperature liquid metal electrodes, representing a significant step forward toward the commercial application of liquid metal batteries.