Co-Doping Engineered High Performance Ni-Rich Layered Cathode

Abstract

Although layered oxides of LiNi_xCo_yMn_zO₂ (NCM, x + y + z = 1) are promising high energy density cathode materials, they still face significant challenges such as the cracks caused by anisotropic strain and poor structural and thermal stability upon building high-performance rechargeable lithium-ion batteries (LIBs) for scale-up industrialization. Under this circumstance, the La and Mg elements are theoretically and experimentally introduced into the layered NCM cathode to modify the primary particles synergistically by the lattice orientation regulation and surface perovskite-phase coating. The synthesized La/Mg co-doped NCM cathode delivers a discharge-specific capacity of 203 mAh g⁻¹ at 0.1 C and 126.2 mAh g⁻¹ at 10 C (1C = 200 mA g⁻¹), which results from the radial grain orientation by incorporating trace amount of dopants, as well as the enhancements on both ionic and electronic conductivities. Further analysis discloses the formation of the La-based perovskite protective layer on the surface, which plays a key role in stabilizing the lattice oxygen ions upon cycling and increasing both structural and thermal stabilities of the cathode. This one-step co-doping strategy provides a rewarding avenue toward developing practical NCM cathodes and high-performance, durable rechargeable Li batteries.