Spinel-stabilized layered LiCoO2 cathode by surface reconstruction strategy

Layered LiCoO2 (LCO) is one of the most successful cathode materials for lithium ion battery due to its high theoretical capacity and high compacted density. Nevertheless, However, several detrimental issues including surface degradation, destructive phase transformation, and inhomogeneous reactions, resulting in rapid capacity fading and short cycle life. Herein, a highly conformal and compatible spinel Li1-xCo2O4 was in situ reconstructed on LCO surface (S-LCO), which can be realized by thermal treating of in situ engineered LiCoO2@ZIF-67 composite experimentally. The intense and stable LiCoO2 and spinel Li1-xCo2O4 can promote rapid Li+ transport and relieve the mechanical stress. Protected by the spinel Li1-xCo2O4, the optimized S-LCO harvests an initial reversible capacity of 171.9 mA h g−1 at 0.2 C within 4.5 V and offers 137 mA h g−1 at 1 C after 200 cycles with 77.0% capacity retention (LCO: 68.5 mA h g−1 with 43.9% capacity retention). The in situ XRD and ex situ SEM characterizations indicate that the spinel Li1-xCo2O4 can effectively enhance phase transformation reversibility (H1→H2→M1→H3→M2) without serious cell shrinkage and microstructure collapse. The feasible surface reconstruction strategy broadens the perspective for developing high-performance LCO-based cathodes.