Pomegranate-like gallium oxide nanospheres coated with nitrogen-doped carbon as an anode for lithium-ion batteries with an ultra-long cycle life

Ga-based materials have emerged as novel self-healing anodes that can spontaneously repair cracks during cycling. However, Ga-based alloying is limited by an unstable solid–electrolyte interphase (SEI) and severe aggregation resulting from the fluidity of Ga. In this study, Ga₂O₃ nanoparticles of ∼20 nm were synthesized. By confining and separating the Ga₂O₃ nanoparticles using doped carbon shells, Ga₂O₃@C with a pomegranate-like structure was successfully fabricated and used as an anode for ultra-long-life lithium-ion batteries. The carbon shell prevents aggregation of the lithium storage reaction product (Ga), provides better electrical conductivity, and forms a more stable SEI. The obtained Ga₂O₃@C anode exhibits a mixed lithium storage mechanism consisting of both diffusion-controlled and capacitive-controlled processes, with a pseudocapacitive contribution of up to 75.0 % at 1.0 mV s⁻¹. The accelerated electrochemical reaction kinetics and high pseudocapacitive contribution of Ga₂O₃@C help deliver excellent cycling stability and rate properties. The Ga₂O₃@C anode can retain a capacity of ∼297.4 mAh g⁻¹ within 3000 cycles at a high current density of 2 A g⁻¹.