Bi@Bi2O3 anchored on porous graphene prepared by solvothermal method as a high-performance anode material for potassium-ion batteries

Abstract

To enhance potassium storage performance of graphene, in situ formed electroactive bismuth nanoparticles were introduced into the porous graphene. The Bi@Bi2O3/graphene composites, which possess the special microstructure that Bi nanoparticles are coated by Bi2O3 and attached to the porous graphene, was synthesized via an environmental-friendly and simple solvothermal method combined with high-temperature sintering under inert environment using graphene oxide, BiCl3 and ethanol as raw materials. Benefiting from the special microstructure and synergistic effect of nano-bismuth particles and graphene, Bi@Bi2O3/graphene composites display better electrochemical performance than graphene. Between 0.01 and 3.0 V (vs K+/K), the electrode was galvanostatically discharged/charged at 100 mA g−1 and the optimal Bi@Bi2O3/graphene composite (Bi@Bi2O3/G-50) has large initial charge capacity (886.4 mAh g−1), which is significantly larger than the theoretic capacities of Bi (385 mAh g−1) and graphene (279 mAh g−1), and after 100 cycles, the high remaining charge capacity of 466.4 mAh g−1 for Bi@Bi2O3/G-50 was obtained. While the remaining charge capacity of graphene is only 112 mAh g−1 after 100 cycles. When electrode cycled at high current density of 800 mA g−1, the initial charge capacities of Bi@Bi2O3/G-50 and graphene are 294.1 and 130 mAh g−1, respectively, and the corresponding remaining capacities are 179.1 and 67.1 mAh g−1, respectively. The results imply that the introduction of high-capacity electroactive materials and the design of special microstructures are effective strategies to significantly improve the potassium storage performance of carbon-based anode materials for potassium-ion batteries.