High-Entropy Induces Self-Limiting and Controllable Surface Coherent Phase Achieving Exceptional Ah-Level Ni-Rich Co-Free Batteries

Traditional views hold that the layered cathodes for lithium-ion batteries must retain the layered characters upon cycling to achieve superior electrochemical performance; the disordered phase transition from the particle surface would severely destroy cycling stabilities. Herein, by integrating tungsten-triangular elements, we propose a Ni-rich cathode with a coherent phase ranging from a homogeneous disordered phase to an ordered structure through charge neutralization. This disordered phase showcases minimal lattice mismatch with the bulk layered structure, thus substantially mitigating the lattice strain at order-disorder phase boundaries. Owing to the self-limiting character of tungsten-triangular elements incorporation in the layered material, the disordered phase was confined to the nanoscale. Particularly, the active elements within the disordered phase were proved reduced electron density at the Fermi level with increasing disorder degree, which not only enhances intrinsic stability but also significantly suppresses catalytic decomposition of electrolytes under high-voltage operation. The property enables the disordered phase to maintain nanoscale integrity through prolonged cycling. This helped the coin cells demonstrate 755.8 Wh kg^-1 specific energy with superior cycling stability, and the assembled Ah-level pouch cells exhibit negligible voltage decay after 1000 cycles. This work provides an approach to design surface coherent phase for development of high-energy batteries.