High stability of LiCoO2 enabled by mixed conductor Li0.33La0.557Ti0.8Cr0.2O3 coating

LiCoO2 has excellent volume energy density, and is the dominant cathode materials for 3 C electronic products. However, the capacity of LiCoO2 is not fully utilized, and its cycle stability is not high enough. To preserve the structural stability of LiCoO2 at high voltage, the mixed ion-electron conductor Li0.33La0.557Ti0.8Cr0.2O3 is coated on LiCoO2 particles, and the effects of coating amount and annealing temperature on the electrochemical performances are systematically investigated. The capacity retention of the pristine LiCoO2 in the range of 2.8–4.5 V is only 51.0% after 200 cycles, which is related to the resistance increase of interface and cracks of cathode particles. The coating layer can improve the interface stability and keep the particles intact, and therefore, the capacity retention of the coated sample is significantly increased to 88.2%.