Optimizing SnO 2- x /Fe 2 O 3 Hetero-Nanocrystals Toward Rapid and Highly Reversible Lithium Storage

Engineering oxygen vacancy and boosting Li2 O reversibility on oxides-based electrode are of significance but remains a challenge in high-power lithium-ion batteries. Herein, the heterogenous SnO2- x /Fe2 O3- y nanocrystals are demonstrated with tailorable x and y values enabled by a glucose-assisted spray combustion technique. Density functional theory calculations unveil the SnO2- x /Fe2 O3 with a maximum x value has the optimal electronic structure, the metallic Fe generated from Fe2 O3 can markedly reduce the free energy to break Li-O bonds for accelerating subsequent delithiation process of Li2 O. Consequently, the optimized SnO2- x /Fe2 O3 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 Li2 O reversibility.