Ti modification to improve the cyclic stability of Ni-rich LiNi0.83Co0.11Mn0.06O2 cathode materials by suppressing mechanical fracture

Abstract

The rapid capacity decay is one of the main reasons to hinder the wide industrial application of the Ni-rich ternary cathode materials for lithium-ion batteries (LIBs). Ti-doping has been systematically studied to overcome this problem. Ti doping can improve mechanical stability, reduce strain, maintain structural integrity, and thus improve electrochemical performances. After 200 cycles, the capacity retention of the 424Ti0.2-NCM sample reaches 89.9% in the voltage range of 2.8–4.5 V, and the initial capacity does not decrease significantly (197.0 mAh g-1). Our results also show that the cycle performance is related not only to the doping amount of Ti but also to the doping method, which can affect the microstructure of cathode particles. The grains of the outer layer of the modified NCM cathode particles obtained by the co-precipitation method are distributed along the radial direction, while grains in the core are equiaxed. And there is also a significant difference in the porosity of the two locations. A moderate amount of porosity in the core can help release the internal stress and avoid the fracture of the particles, which contributes to improved cycling performance.