Electrolyte reactivity, oxygen states, and degradation mechanisms of nickel-rich cathodes
M. Peiris, Diana Liepinya, Hao Liu, Manuel Smeu
Abstract
Understanding interactions at electrode interfaces is a key aspect of building better batteries. This work explores the interface between fully lithiated/delithiated Ni-rich cathodes and organic electrolytes using density functional theory and ab initio molecular dynamics. By analyzing the behavior of LiBF 4 and LiPF 6 salts, we gain valuable insights into atomic-level interactions at the cathode-electrolyte interface. We observe significantly higher surface activity in delithiated cathodes relative to lithiated cathodes (forming O 2 species in peroxide form), transitioning from a singlet state into a triplet state while being released from the cathode. Ethylene carbonate dissociation, triggered by surface oxygen radicals, often generates CO 2 and CO on the surface. Variations in Ni and O atomic charges reveal how different lithiation levels affect surface behavior, while the degree of hydrogen passivation significantly influences surface degradation. Lower passivation promotes O 2 evolution, while higher levels lead to H 2 O formation. These findings highlight the potential of targeted surface modifications to enhance battery performance and safety.