High-Entropy Doped Ni-Rich Oxide Cathodes with Alleviated H2–H3 Phase Transition for Li-Ion and All-Solid-State Li Batteries

High-capacity Ni-rich cathodes hold considerable promise in advancing both high-energy Li-ion batteries (LIBs) and all-solid-state Li batteries (ASSLBs). Yet, lattice volume changes induced by the H2–H3 phase transition lead to structural degradation. It has been demonstrated that doping approaches can enhance structural stability. Nevertheless, the selection of an appropriate dopant is of considerable importance for the design of high-performance Ni-rich materials with high-entropy doping. Furthermore, the feasibility of high-entropy doped Ni-rich cathodes in ASSLBs has not been reported to date. In this study, leveraging the chemically competitive doping mechanism of Mg, Al, Ti, Nb, and Mo elements, we propose a high-entropy doped LiNi0.8Co0.1Mn0.05Mg0.01Al0.01Ti0.01Nb0.01Mo0.01O2 (HE-NCM) to stabilize Ni-rich cathodes. In-situ X-ray diffraction confirms that the synergistic effect of multiple dopants in high-entropy doping significantly alleviates the H2–H3 phase transition and reduces lattice volume changes, which contribute to the absence of microcracks and improved bulk/interface stability. In ASSLBs, the HE-NCM@LiNbO3 maintains an outstanding capacity retention of 84.5% even after 1700 cycles, demonstrating the feasibility of high-entropy doped Ni-rich cathodes when matched with a sulfide solid-state electrolyte. The application of high-entropy doping methodology for the development of advanced rechargeable batteries has been shown to provide a novel perspective on the improvement of the structural robustness and interfacial compatibility of Ni-rich cathode materials.