Fe₂O₃ Nanoparticle Seed Catalysts Enhance Cyclability on Deep (Dis)charge in Aprotic LiO₂ Batteries

Abstract Although the high energy density of LiO₂ chemistry is promising for vehicle electrification, the poor stability and parasitic reactions associated with carbon‐based cathodes and the insulating nature of discharge products limit their rechargeability and energy density. In this study, a cathode material consisting of α‐Fe₂O₃ nanoseeds and carbon nanotubes (CNT) is presented, which achieves excellent cycling stability on deep (dis)charge with high capacity. The initial capacity of Fe₂O₃/CNT electrode reaches 805 mA h g⁻¹ (0.7 mA h cm⁻²) at 0.2 mA cm⁻², while maintaining a capacity of 1098 mA h g⁻¹ (0.95 mA h cm⁻²) after 50 cycles. The operando structural, spectroscopic, and morphological analysis on the evolution of Li₂O₂ indicates preferential Li₂O₂ growth on the Fe₂O₃. The similar d‐spacing of the (100) Li₂O₂ and (104) Fe₂O₃ planes suggest that the latter epitaxially induces Li₂O₂ nucleation. This results in larger Li₂O₂ primary crystallites and smaller secondary particles compared to that deposited on CNT, which enhances the reversibility of the Li₂O₂ formation and leads to more stable interfaces within the electrode. The mechanistic insights into dual‐functional materials that act both as stable host substrates and promote redox reactions in LiO₂ batteries represent new opportunities for optimizing the discharge product morphology, leading to high cycling stability and coulombic efficiency.