Integrated Local-Microstructure Engineering Toward Mechanochemically Robust Ultra-High Nickel Cathodes.

Abstract

Ni-rich layered cathodes show exceptional promise for next-generation high-energy-density lithium-ion batteries. However, higher nickel utilization in layered cathodes readily exacerbates both bulk mechanical failure and interfacial chemistry instability, significantly hindering their practical application. Herein, a comprehensive local lattice regulation strategy was proposed via Mg/Nb co-doping, which constructed a chemically and mechanically co-robust LiNi_0.95Co_0.03Mn_0.02O₂ cathode from surface to bulk. The surface-reconstructed ultrathin disordered rock-salt phase effectively stabilized the electrochemical interface. Meanwhile, the bulk cation-disordered structure integrated with a coherent spinel-like phase mitigated lattice strain and enhanced structural integrity. Therefore, the modified ultra-high nickel cathode exhibited excellent long-term cycling stability, high rate capability, and thermal stability. It exhibited high initial coulombic efficiency of 93.24% and a discharge specific capacity of 240.11 mAh·g^-1 at 0.1C. It could also deliver a high initial capacity of 210.44 mAh·g^-1 at 1C and retain 97.37% of its capacity after 100 cycles. Moreover, it exhibited outstanding performance during cycling at 3C, delivering a superior capacity retention of 81.65% after 500 cycles. It also delivered a remarkable specific capacity of 147.43 mAh·g^-1 even at the rate of 15C. This integrated microstructure regulation strategy would pave the way for commercializing ultra-high-nickel cathodes in next-generation high-energy-density batteries.