Dynamic heterojunctions enabled by liquid metal for high-performance silicon anodes

Abstract

The exertion of the full capacity of non-conducting silicon anodes inevitably leads to severe volume expansion, which critically limits their practical viability. In our work, a simple liquid metal (LM) coating strategy is introduced to engineer dynamic heterojunction interfaces on Si/C particle surfaces. Leveraging the reversible solid–liquid phase dynamic transition behavior of LM during (de)lithiation, the interface provides solid-phase mechanical buffering during lithiation and liquid-phase flowability upon delithiation, effectively repairing the structural voids and maintaining interfacial continuity under large volume fluctuations. Theoretical calculations reveal that the strong Li–Ga interaction and superior Ga conductivity contribute to improved electronic and ionic kinetics at the interface. As a result, the LM–Si/C anode exhibits a previously unreported cyclic capacity recovery behavior, attributed to phase-induced interfacial remodeling. The electrode delivers a high capacity of 680 mAh g⁻¹ at 2 A g⁻¹, excellent cyclability (500 cycles with 61% retention), and a substantial reduction in electrode thickness expansion from 64.1% to 18.5%. Full-cell tests confirm the practicality of this design. This work establishes a mechanistically guided, phase-adaptive interfacial strategy for advancing silicon-based lithium-ion batteries.