Regulating the Multiscale Stability of Li‐Rich Cathode through Lewis Acid Gas Treatment

Abstract Lattice oxygen redox reactions dedicate the extra retrievable capacities from the lithium‐rich layered oxides (LLOs) cathodes, however, the widespread adoption of which in the energy‐dense batteries faces a series of obstacles, such as oxygen loss during the initial activation, cycling‐induced structural degradation as well as the retard Li + diffusivity impeded by the interfacial impurities. Here, a Lewis acid gas treatment of LLOs is proposed, namely the PF 5 etching to enhance the cycling endurance and high‐temperature tolerance of the electrode. The multiscale modifications involve the F − doping in the bulk lattice, the phosphate coating to kinetically suppress the O 2 release as well as the removal of surface impurities in a single step. The gas‐phase treatment constructs a continuous pathway across the densely‐packed LLO electrode, enhancing Li + diffusivity by fivefold compared to the untreated electrode. Notably, the transmission‐mode operando X‐ray diffraction of the modified LLOs cathode confirms a 71.4% reduction of self‐discharge rate during the idle charged state at 55 °C, as well as the 16% mitigation of lattice contraction (Δ c/a ) during the dynamic galvanostatic cycling. By pairing the lithium foil (50 µm) with the modified LLO cathode (12.75 mg cm −2 ) in a pouch‐format cell model, the 0.2 Ah prototype achieves the gravimetric energy/power densities as well as cycling endurance across a wide temperature range. This scalable, Lewis‐acid gas modification strategy presents a practical approach for deploying LLOs in energy‐dense cell prototyping.