Three-Dimensionally Mesostructured Fe2O3 Electrodes with Good Rate Performance and Reduced Voltage Hysteresis

Ni scaffolded mesostructured 3D Fe2O3 electrodes were fabricated by colloidal templating and pulsed electrodeposition. The scaffold provided short pathways for both lithium ions and electrons in the active phase, enabling fast kinetics and thus a high power density. The scaffold also resulted in a reduced voltage hysteresis. The electrode showed a reversible capacity of ∼1000 mAh g−1 at 0.2 A g−1 (∼0.2 C) for about 20 cycles, and at a current density of 20 A g−1 (∼20 C), the deliverable capacity was about 450 mAh g−1. The room-temperature voltage hysteresis at 0.1 A g−1 (∼0.1 C) was 0.62 V, which is significantly smaller than that normally reported in the literature. The hysteresis further reduced to 0.42 V at 45 °C. Potentiostatic electrochemical impedance spectroscopy (PEIS) studies indicated that the small voltage hysteresis may be due to a reduction in the Li2O/Fe interfacial area in the electrode during cycling relative to conventional conversion systems.