Theoretical Insights into High-Entropy Ni-Rich Layered Oxide Cathodes for Low-Strain Li-Ion Batteries

Ni-rich, Co-free layered oxide cathode materials are promising candidates for next-generation Li-ion batteries due to their high energy density. However, these cathode materials suffer from rapid capacity fading during electrochemical cycling. To overcome this shortcoming, so-called high-entropy (HE) materials, which are obtained by incorporating multiple dopants, have been suggested. Recent experimental work has shown that HE Ni-rich cathode materials can offer excellent capacity retention on cycling, although a thorough rationale for this has yet to be provided. Here, we present classical and first-principles calculations to elucidate the salient features of HE layered oxides as cathode materials in Li-ion batteries. We suggest that a combination of five prime factors may be responsible for the enhanced performance of HE Ni-rich layered oxide cathode materials over other Ni-rich cathodes: (1) low crystal lattice variation, (2) invariant local crystal field environment, (3) strong metal-oxygen bonding, (4) low degree of antisite defects, and (5) low operational voltage.