Nb/Al Codoping Strategy for Nickel-Rich Cathodes to Improve Rate and Cycle Performance of Lithium-Ion Batteries

Nickel-rich layered LiNi0.8Co0.1Mn0.1O2 holds significant potential as a commercially viable cathode material. However, its widespread application is still hindered by inherent challenges, including poor structural stability, cycling performance, and rate capability. This study presents an Nb/Al codoped Li(Ni0.8Co0.1Mn0.1)0.98Nb0.01Al0.01O2 single-crystal ternary cathode material developed to overcome these challenges. The Nb and Al dopants are uniformly distributed throughout the material, resulting in the formation of an α-LiAlO2 protective layer on the surface. This protective layer effectively reduces electrolyte degradation and facilitates Li+ diffusion. Additionally, some of the TM-O bonds are replaced by Nb–O and Al–O bonds, which minimizes the intermixing of Li+ and Ni2+, thus improving the stability of the layered structure. The Nb/Al codoped nickel-rich single-crystal ternary cathode material exhibits superior cycling stability and rate performance compared to the undoped material. After 200 cycles at 1 C within the voltage window of 2.75–4.5 V, the NA-SNCM delivers a specific capacity retention rate of 76.11% (133.65 mA h g–1). Notably, the undoped counterpart displays severe microcracking, whereas the doped samples maintain intact crystallinity.