Direct electrochemical reduction of solid Bi2O3 to Bi as a high-performance anode for sodium-ion batteries using deep eutectic solvent

The direct reduction of solid Bi2O3 to Bi used for a high-performance anode is studied for the first time. Cyclic voltammetry results indicate that the conversion of solid Bi2O3 is a one-step process. Electrolysis measurements using a solid Bi2O3 cathode were carried out at various experimental conditions. X-ray diffraction (XRD) measurements of the electrolytic samples reveal that the solid Bi2O3 can be completed reduced to Bi. The electrolytic Bi obtained at 2.6 V for 6 h achieves a long and steady cycle, a higher specific capacity than 403.2 mAh g−1, and a higher capacity retention than 95.5 % cycling for even 4000 cycles, as well as an excellent rate capability. The electrochemical deoxidation approach can provide a green and straightforward pathway for producing high-performance sodium-ion batteries anodes. •The conversion of solid Bi2O3 is a one-step process.•Electrolytic Bi anode displays excellent sodium storage performance.•Electrolytic Bi anode delivers a capacity of 403.2 mAh g−1 after 4000 cycles at 2 A g−1.•The preparation process is a green and straightforward pathway.