Enabling the Nb/Ti co-doping strategy for improving structure stability and rate capability of Ni-rich cathode

Abstract

High-capacity Ni-rich layered cathodes LiNi_xCo_yMn_1−x−yO₂ (NCM) have been widely recognized as highly promising candidates for lithium-ion batteries (LIBs). However, NCM cathodes are suffered from sluggish Li-ion kinetics and fast capacity decay. Herein, the Nb/Ti co-doping strategy has been proposed by formation energy analysis to enhance the mechanical and chemical integrities of NCM cathode. Nb/Ti co-doping facilitates Li-ion transport of NCM cathode for boosting the rate ability. Furthermore, the structure stability is prominently improved for the stronger NbO and TiO bonds, resulting from the suppressed sharp contraction of c axis, inhibited microcracks formation, and alleviated electrolyte corrosion. Inspired by the synergistic effect of Nb/Ti co-doping, the modified NCM exhibits superior comprehensive electrochemical performances. The Nb/Ti co-doping NCM exhibits an increased discharge capacity of 144.3 mAh/g at 10 C and an outstanding capacity retention remained 92.7 % after 300 cycles at 1 C. This work offers a promising approach to developing high-performance cathode materials.