Non-solvent-induced phase separation as a scaffold-forming strategy for honeycomb carbon-encapsulated EGaIn lithium-ion battery anodes

Alloy-type anodes offer higher lithium-storage capacity than graphite, but repeated alloying and dealloying cause substantial volume changes, structural pulverization, and loss of electrical contact. Room-temperature eutectic gallium-indium (EGaIn) can accommodate alloying-induced strain through its fluidity; however, bare droplets can agglomerate, causing electrode swelling and destabilizing the electrode architecture. Here, we employ non-solvent-induced phase separation (NIPS) as a scaffold-forming strategy to confine EGaIn nanoparticles within a polyacrylonitrile-derived honeycomb carbon framework (EGaIn@HCC). Solvent/non-solvent exchange simultaneously generates porosity, spatially distributes the liquid-metal nanoparticles, and forms a carbonizable precursor. Subsequent stabilization and carbonization produce an interconnected honeycomb carbon scaffold containing approximately 70 wt% EGaIn while providing internal free volume to accommodate volume changes and continuous electron- and ion-transport pathways. The resulting EGaIn@HCC anode delivers 698 mAh g −1 after 100 cycles at 0.1C with 86.3% capacity retention and maintains 337 mAh g −1 after 500 cycles at 1C with 82.3% retention and approximately 99.96% Coulombic efficiency. Structural and chemical characterization confirms the confinement of EGaIn within the porous carbon framework, while electrochemical analyses indicate improved reaction kinetics, preserved charge-transfer accessibility, and sustained Li-ion transport.