Higher Than 90% Initial Coulombic Efficiency with Staghorn‐Coral‐Like 3D Porous LiFeO_2−x as Anode Materials for Li‐Ion Batteries

Abstract Transition metal oxides represent a promising class of anode materials for high‐capacity lithium‐ion batteries. However, low initial coulombic efficiency (ICE, <80%) still remains a crucial challenge for practical applications. Herein, a unique 3D Fe(II)‐rich porous LiFeO_2−x comprising of staghorn‐coral‐like skeleton measuring ≈100 nm in diameter is demonstrated, which is readily prepared by reacting Fe₂O₃ with LiH at 550 °C. When used as an anode material, the Fe(II)‐rich LiFeO_2−x delivers the presently known highest ICE value of 90.2% with 1170 mAh g⁻¹ discharge capacity. The high ICE value can be ascribed to a fast conversion reaction of LiFeO_2−x upon lithiation/delithiation facilitated by the presence of Fe(II), which generates oxygen vacancies and makes electron transportation much easier, based on the experimental results and density functional theory (DFT) calculations.