Improvement of electrochemical performance and structural stability of LiNi0.83Co0.12Mn0.05O2 at high-voltage by La and Ti modification

Abstract

The large-scale commercialization of Ni-rich LiNi1−x-yCoxMnyO2 is hindered by the rapid capacity decay, which is caused by structural instability, interface side reaction, and surface phase transition. In this study, the Ni-rich cathode is modified with Ti and La through a one-step sintering method. Ti and part La diffuse into the cathode particles, and the rest of La is coated on the surface of the particles in the form of La4NiLiO8. The La and Ti modified cathodes show excellent cycling performance even at a high cut-off voltage of 4.5 V. The modified cathode has an initial capacity of 195.5 mAh g−1 and capacity retention of 87% after 200 cycles. The rate performance is also improved, and the capacity at 5 C reaches 178.3 mAh g−1. The improved cycling performance is attributed to the modification of La and Ti, which avoids structural degradation and maintains the mechanical integrity of the cathode particles during cycling. The improvement in rate performance is attributed to the fact that the Li+ diffusion coefficient is increased due to the modification.