Graft Copolymer-Stabilized Liquid Metal Nanoparticles for Lithium-Ion Battery Self-Healing Anodes

Abstract

The use of eutectic gallium indium (EGaIn) liquid metal alloy as anodes for lithium-ion batteries (LIBs) has been extensively studied owing to its shape-deformable and self-healing properties. However, to limit the damage to EGaIn anodes resulting from volume expansion during lithiation and delithiation, chemical modifications are required to stabilize the liquid metal as nanoparticles. This study introduces a novel self-healing liquid metal anode with grafted polymer ionic channels to enhance the stability and rate capability of LIBs. The fluorinated polymer binder grafted with ionomers effectively suppresses liquid metal aggregation, stabilizing the liquid metal nanoparticles. Additionally, the fluorinated polymer binder provides ionic channels that facilitate lithium-ion migration from the electrolyte to the surfaces of the liquid metal nanoparticles. The efficient electrochemical reduction of lithium ions on these surfaces results in high-performance LIBs, which is demonstrated by the improved stability (85% retention after 500 cycles at 0.5 A g⁻¹), rate capability (45.1% at 2.0 A g⁻¹), and cell capacity (803.7 mAh g⁻¹ at 0.1 A g⁻¹). Anodes containing the grafted copolymer to stabilize the liquid metal nanoparticles can be scaled using simple solution processes, providing an effective strategy for developing high-performance liquid metal-based LIBs.