Understanding how off-stoichiometry promotes cation mixing in LiNiO₂

2024/01/11 by Cem Komurcuoglu, Yunhao Xiao, Komurcuoglu, Cem +11
Engineering · #Advanced Battery Technologies Research #Advancements in Battery Materials #Extraction and Separation Processes #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)

paper · pdf · doi:10.48550/arxiv.2401.05983

openalex publication_date 2024/01/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Although LiNiO₂ is chemically similar to LiCoO₂ and offers a nearly identical theoretical capacity, LiNiO₂ and related Co-free Ni-rich cathode materials suffer from degradation during electrochemical cycling that has prevented practical use in Li-ion batteries. The observed capacity decay of LiNiO₂ has been attributed to the formation of structural defects via Li/Ni cation mixing that reduces cyclability and leads to poor capacity retention. Herein, we investigate the kinetics and thermodynamics of Li/Ni mixing in ideal LiNiO₂ and off-stoichiometric Li_1-zNi_1+zO₂. We find that ideal LiNiO₂ is stable against cation mixing with similar characteristics as LiCoO₂. Li/Ni mixing is promoted by extra Ni in the Li layers that cannot be avoided in synthesis. Our study elucidates the crucial role of extra Ni atoms on Li sites in the cation mixing mechanism, an insight that can inform the development of Co-free cathode materials.

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