Entropy‐Assisted Doping Strategy Enabling Chemo‐Mechanically Reliable Ultrahigh‐Ni Co‐Free Polycrystalline Cathode for Commercializable Lithium‐Ion Batteries

Abstract Recently, Co‐free Ni‐rich cathodes have received extensive concerns as a competitive candidate for next‐generation sustainable lithium‐ion batteries (LIBs) due to their high‐capacity/operation voltage merits and elimination of expensive Co component. However, it is extremely challenging to solve the issues involving their intrinsic chemo‐mechanical instabilities triggered by anisotropic lattice stress and short cycle life. Herein, we rationally incorporate tiny quintuple high‐valence cations to engineer an entropy‐assisted LiNi 0.9 Mn 0.085 Nb 0.003 W 0.003 Sb 0.003 Ta 0.003 Mo 0.003 O 2 (denoted as EL‐N9‐3) as a competitive cathode for LIBs. Thanks to such multi‐component synergistic superiorities, the five‐cations modulated EL‐N9‐3 is endowed with a robust lattice structure and optimized crystallographic texture, thereby significantly strengthening lattice oxygen framework, mitigating surface side‐reactions and irreversible phase transitions, and further prohibiting the microcracks formation and reproduction. The well‐designed EL‐N9‐3 cathode demonstrates exceptional long‐cycle duration, showing a competitive capacity retention of 86.7 % after 200 cycles at an elevated cut‐off potential of 4.5 V. Besides, the EL‐N9‐3‐based pouch‐type full cell can steadily sustain 500 cycles within a wide voltage window of 2.8–4.4 V at 1 C rate, with 70.8 % capacity retention. This work proves that the entropy‐assisted complex doping strategy is an effective avenue to achieve advanced Co‐free ultrahigh‐Ni layered cathodes, definitely expediting their extensive utilization in next‐generation LIBs.