Structural evolution of α-Fe2O3 nanowires during lithiation and delithiation

This work describes the evolution of α-Fe2O3 nanowires during the conversion reaction associated with lithium intercalation. An electrical resistive heating method synthesizes single crystal hematite (α-Fe2O3) nanowires. Transmission electron microscopy characterizes this anode material at various stages of lithiation and delithiation. The process initiates through the reduction of α-Fe2O3 to nanocrystalline Fe3O4. Further lithiation converts all of the iron oxide to nanocrystalline BCC Fe. During delithiation, the reactions proceed via conversion of Fe0 to Fe2O3. However, a nanocrystalline structure replaces the initial single crystalline α-Fe2O3 after the first circle. This polycrystalline nanowire structure persists for over 30 cycles.