NiGa₂O₄/rGO Composite as Long-Cycle-Life Anode Material for Lithium-Ion Batteries

This work reports a novel Ga-based material, NiGa₂O₄, which is typically used as a photocatalyst for water splitting, as an anode for Li-ion battery with a long cycle life. High-surface-area reduced graphene oxide (rGO) has been used as the conductive substrate to avoid the aggregation of NiGa₂O₄ nanoparticles (NPs). Because the size and shape of NiGa₂O₄ are very sensitive to the pH of the precursor, ethylene glycol has been employed as the solvent, as well as the reduction agent to reduce GO, to avoid using extra surfactants and also to avoid the variation of pH of the precursor. The obtained NiGa₂O₄/rGO composite possesses high capacity and long cycle life (2000 cycles, 2 A/g), with NiGa₂O₄ NPs around 3-4 nm that are uniformly distributed on the rGO surface. Full cell performance with LiCoO₂ as cathode has also been studied, with the average loss of 0.04% per cycle after 100 cycles (C/2 of LiCoO₂). The long cycle life of the composite was ascribed to the self-healing feature of Ga⁰ formed during charging.