La4NiLiO8-assistant surface reconstruction to realize in-situ regeneration of the degraded nickel-rich cathodes

Abstract

The cost-effectiveness and higher energy density of nickel-rich cathodes have made them appealing for electric vehicles, generating significant interest in their advancement. Unfortunately, the cathodes' high surface activity presents a challenge in humid air conditions, leading to structural degradation. The deterioration leads to the creation of the NiO rock-salt structure and residual lithium, impeding the pathways for Li+ movement throughout the entire system. Concurrently, the reduction of unstable Ni3+ triggers the generation of reactive oxygen species, causing the emergence of oxygen vacancies. These vacancies, in turn, diminish the cathode's structural stability. Herein, to mitigate the degradation of nickel-rich cathodes following storage, a surface reconstruction technique was employed to convert residual lithium and NiO phase into a conductive La4NiLiO8 repair layer. This in-situ regeneration resulted in an impressive regenerative electrochemical capacity of 56.2 mAh/g at 1C for the 28d-1La sample. Additionally, the surface reconstruction technique effectively decreased the concentration of oxygen vacancies, resulting in improved durability of the cathode structure. Furthermore, the La4NiLiO8 repair layer effectively suppressed detrimental phase transitions and mitigated electrolyte corrosion. This study presents a straightforward and efficient regeneration strategy for degraded nickel-rich cathodes resulting from storage.