Improving Electrochemical Performance and Structural Stability of Cobalt-Free Nickel-Rich Cathode Materials through Entropy-Assisted Doping

Cobalt-free nickel-rich layered oxides, as the next-generation cathode materials for high-energy-density lithium-ion batteries, have attracted much attention due to their high energy density and low-cost advantages, but their cycling stability and structural degradation issues still restrict practical applications. In this work, a multielemental synergistic doping strategy is designed to modify LiNi 0.9 Mn 0.1 O 2 (NM), where high oxidation state elements (Ti 4+, Mo 6+, Nb 5+ ) and Al 3+ are introduced into the transition metal element layer by a one-step solid-phase method to build up entropy-assisted effects and improve the structural stability and electrochemical properties of the material. High-valent metal elements can effectively prevent cation mixing and improve the material’s cycling performance, while Al 3+ doping can strengthen metal–oxygen bonds with oxygen and increase the stability of lattice oxygen, preventing structural degradation. These benefits enable the modified cathode material (NM-ATMN) to demonstrate outstanding cycling and multiplication capabilities. After 150 cycles at 1C, the optimized material, NM-ATMN, has an 82.7% capacity retention, which is more than 50% better than that of the undoped sample NM (52.2%). This work offers a novel solution to the special problems of nickel-rich cathode materials without cobalt, such as poor cycling performance and structural fragility.