Self-healing liquid metal nanoparticles encapsulated in hollow carbon fibers as a free-standing anode for lithium-ion batteries

Abstract

As a novel self-healing material, room-temperature liquid metal (LM) composed of Ga and Sn is a promising anode in lithium-ion batteries (LIBs). Although there is no structural pulverization of the anode material with self-healing ability, the volume change during cycling may cause cracks in the supporting structure, such as binders or conductive additives, and thus significantly limits the cycling stability and high capacity for lithium-alloy electrodes. Here, novel self-healing core-shell fibers, with liquid metal nanoparticles as the core coated with a carbon shell (denoted as LMNPs@CS fibers), were synthesized by facile coaxial electrospinning and a carbonization process. The as-prepared fibers, which encapsulated nanosized self-healing LM particles with a well-designed inner void space of the shell, served as free-standing anodes for LIBs. Such anodes offered a reversible capacity of 603.9 mAh g−1 at 1000 mA g−1, excellent rate capability, and a highly stable cycling performance with a discharge capacity of 552 mAh g−1 after 1500 cycles at 1000 mA g−1. The superior electrochemical performance can be attributed to (1) the self-healing ability of the LMNPs, which ensured the superior cycling performance of the electrode, (2) the unique core-shell structure with a well-designed void space, which alleviated the volume changes of LMNPs during the lithiation/delithiation processes, and (3) the self-healing LMNPs, composed of Ga and Sn, possessed high theoretical capacities. These promising strategies and associated opportunities demonstrate great potential for fabricating advanced self-healing anode materials for LIBs.