Facile Synthesis of Multi-Channel Surface-Modified Amorphous Iron Oxide Nanospheres as High-Performance Anode Materials for Lithium-Ion Batteries

Based on the synergistic effect of ripening and hydrogen ion etching in a hydrothermal solution, a simple, facile, and low-cost new strategy was demonstrated to prepare multi-channel surface-modified amorphous Fe2O3 nanospheres as anodes for Li-ion batteries in this study. Compared with polycrystalline Fe2O3, the conversion reaction between amorphous Fe2O3 and lithium ions has a lower Gibbs free energy change and a stronger reversibility, which can contribute to an elevation in the cycle capability of the electrode. Meanwhile, there are abundant active sites and more effective dangling bonds/defects in amorphous materials, which is beneficial to promote charge transfer and lithium-ion migration kinetics. The Galvanostatic intermittent titration analysis results confirmed that the amorphous Fe2O3 electrode had a higher Li+ diffusion coefficient. In addition, the surfaces of the amorphous nanospheres are corroded to produce multiple criss-cross channels. The multi-channel surface structure can not only increase the contact area between Fe2O3 nanospheres and electrolyte, but also reserve space for volume expansion, thereby effectively alleviating the volume change during the intercalation-deintercalation of lithium ions. The electrochemical performance showed that the multi-channel surface-modified amorphous Fe2O3 electrode exhibited a higher specific capacity, a more stable cycle performance, and a narrower voltage hysteresis. It is believed that amorphous metal oxides have great potential as high-performance anodes of next-generation lithium-ion batteries.