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

Abstract

Nickel-rich layered LiNi_0.8Co_0.1Mn_0.1O₂ 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(Ni_0.8Co_0.1Mn_0.1)_0.98Nb_0.01Al_0.01O₂ 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.