There is a great deal of interest in developing battery systems that can exhibit self-healing behavior, thus enhancing cyclability and stability. Given that gallium (Ga) is a metal that melts near room temperature, we wanted to test if it could be employed as a self-healing anode material for lithium-ion batteries (LIBs). However, Ga nanoparticles (NPs), when directly applied, tended to aggregate upon charge/discharge cycling. To address this issue, we employed carbon-coated Ga2O3 NPs as an alternative. By controlling the pH of the precursor solution, highly dispersed and ultrafine Ga2O3 NPs, embedded in carbon shells, could be synthesized through a hydrothermal carbonization method. The particle size of the Ga2O3 NPs was 2.6 nm, with an extremely narrow size distribution, as determined by high-resolution transmission electron microscopy and Brunauer-Emmett-Teller measurements. A lithium-ion battery anode based on this material exhibited stable charging and discharging, with a capacity of 721 mAh/g after 200 cycles. The high cyclability is due to not only the protective effects of the carbon shell but also the formation of Ga0 during the lithiation process, as indicated by operando X-ray absorption near-edge spectroscopy.
Keywords: anode materials; gallium oxide; hydrothermal carbonization; lithium-ion batteries; self-healing.