Oxidation-promoting strategy boosts highly ordered Co-free Ni-rich layered oxides

Nickel-rich cobalt-free cathodes are considered as an attractive candidate for next-generation lithium-ion batteries in terms of economic efficiency, environmental friendliness, and energy density. However, high-nickel and zero-cobalt contents are prone to induce layered oxide cathode active materials (CAMs) with undesirable anti-site defects (Li⁺/Ni²⁺ mixing) and a defective interface (rock-salt phase layer). Herein, a highly ordered structural LiNi_0.80Mn_0.17Al_0.03O₂ CAM was successfully synthesized via the active Li₂O₂ boosted method. The significant reduction in Li⁺/Ni²⁺ mixing (5.5%→2.9%) and thickness of the rock-salt phase interface (5 nm→1.2 nm) vigorously verify the feasibility of this strategy. The evolution of the Ni²⁺/Ni³⁺ proportion and primary particle size can further illustrate the co-oxidation mechanism of this strategy. In-situ XRD also shows that the degree of H2-H3 phase transition in the modified sample is relieved, which alleviates the volume change. As a result, the optimized sample displays enhanced cyclability (162.60 mAh/g at 1C over 100 cycles) and advanced rate performance (124.29 mAh/g at 5C).