Ceria Heterostructure Suppresses Oxygen Release of Na-Ion Battery Cathode Materials

Oxygen anionic redox in transition metal (TM) layered oxide cathodes can offer large extra capacity at high operating voltage. However, this oxygen-involved chemical evolution is usually accompanied by lattice oxygen release, resulting in metal dissolution, voltage fading, and capacity decay. Herein, ultrathin ceria heterostructures were constructed at the surface of the Na2/3Ni1/3Mn2/3O2 (NNM) cathode, which shared similar hexagonal atomic arrangements with the Ni/Mn layer. This phase-compatible combination could form Ce–O–TM bonding at the NNM/ceria interphase for the stabilization of lattice oxygen anions, which effectively suppresses the oxygen release in the deep desodiated state and alleviates the Ni/Mn metal dissolution. By being composited with 5% ultrathin CeO2–x, the oxygen release behavior of the NNM cathode has been successfully suppressed and the modified NNM/CE-5 cathode displays highly competitive cycling stability (75.3% capacity retention after 100 cycles at 0.5 C), excellent voltage stability and high-rate capability. This work provides a successful strategy to construct strong interphase bonding for cathode materials to stabilize anionic redox at a high operating voltage.