Laser-Synthesized Metastable Bismuth Nanocrystals Chemically Bonded to Reduced Graphene Oxide for Excellent Lithium Storage
The poor interface contact between bismuth (Bi) nanoparticles and reduced graphene oxide (rGO) impedes ion/electron transfer in lithium-ion battery anodes. We report an innovative fabrication of ultrafine Bi nanocrystals chemically bonded to rGO (Bi-rGO) via liquid-phase pulsed laser irradiation followed by solvothermal reaction with graphene oxide. Metastable Bi nanocrystals synthesized by laser (5.5 nm) undergo lattice restructuring and shrink to a record-small size of 2 nm during solvothermal combination, the smallest reported for Bi/C composites. The Bi nanocrystals are uniformly anchored onto rGO nanosheets via strong Bi–O–C bonds, which suppress particle aggregation, establish efficient ion/electron transport channels, and alleviate volume expansion during lithiation. The Bi-rGO-2 anode, comprising 2 nm Bi nanocrystals, delivers an exceptional reversible capacity of 586.7 mAh g−1 over 500 cycles at 100 mA g−1, nearly doubling that of a Bulk Bi/rGO composite anode (318 mAh g−1). Theoretical calculations confirm higher binding energy between Bi and rGO at smaller particle sizes, while kinetic analysis reveals accelerated Li+ diffusion. This work provides a scalable route to high-performance alloy anodes through metastable nanocrystal engineering and covalent interface coupling.