Optimizing SnO2−x/Fe2O3 Hetero‐Nanocrystals Toward Rapid and Highly Reversible Lithium Storage

Abstract

Engineering oxygen vacancy and boosting Li₂O reversibility on oxides-based electrode are of significance but remains a challenge in high-power lithium-ion batteries. Herein, the heterogenous SnO_2−x/Fe₂O_3−y nanocrystals are demonstrated with tailorable x and y values enabled by a glucose-assisted spray combustion technique. Density functional theory calculations unveil the SnO_2−x/Fe₂O₃ with a maximum x value has the optimal electronic structure, the metallic Fe generated from Fe₂O₃ can markedly reduce the free energy to break Li–O bonds for accelerating subsequent delithiation process of Li₂O. Consequently, the optimized SnO_2−x/Fe₂O₃ exhibits a remarkably enhanced electrochemical reversibility and reaction kinetics. After stabilized by reduced graphene oxide, the hybrid delivers a high reversible specific capacity of 1113 mAh g⁻¹ with superior rate performance (474 mAh g⁻¹ at 20 A g⁻¹) and long cycle life (negligible loss after 500 cycles at 5 A g⁻¹), the oxygen vacancy and microstructure are well-maintained after cycles. This work provides the possibilities for skillfully regulating oxygen vacancy and meantime enhancing Li₂O reversibility.