Design High-Entropy Core-Shell Nickel-Rich Cobalt-Free Cathode Material Toward High Performance Lithium Batteries

Abstract

The structural instability of lithium-based transition metal layered oxides during electrochemical cycling-exacerbated by phenomena such as metal dissolution and phase transitions-induces rapid capacity degradation, thus constraining their applicability in high-energy-density lithium batteries. While coating these materials can bolster stability, the employment of electrochemically inactive coatings may inadvertently undermine energy storage performance, presenting a significant trade-off. In response to this challenge, an innovative core-shell cathode architecture is presented, wherein high entropy doped LiNi_1/6Mn_1/6Al_1/6Ti_1/6Mo_1/6Ta_1/6O₂ serves as the shell and nickel-rich cobalt-free LiNi_0.89Mn_0.11O₂ constitutes the core, synthesized through a simple two-step co-precipitation methodology (designated as LHECNM). This high-entropy shell preserves the core's electrochemical performance while effectively mitigating phase transformations and transition metal ion dissolution, thereby enhancing structural robustness. Moreover, the core-shell configuration significantly diminishes the energy barrier for Li⁺ diffusion, facilitating superior ion transport dynamics. Consequently, LHECNM demonstrates remarkable electrochemical performance, achieving a discharge capacity of 201.57 mAh g⁻¹, a commendable rate capability up to 5C, and an impressive 92% capacity retention over prolonged cycling. This investigation elucidates a promising paradigm for the design of high-entropy cathode materials, offering profound insights for the advancement of future energy storage technologies.