Self-repaired cathode electrolyte interphase to stabilize the high-nickel cathode interface by a sustained-release multifunctional electrolyte additive

Abstract

Increasing the nickel content in high-nickel LiNixCoyMn1-x-yO2 cathode materials (NCM) can boost their energy density. However, the consequence of rising Ni content in NCM consists in the heightened stress buildup, intensified irreversible phase transition and severe electrolyte decomposition, and consequently accelerating the battery’s degradation. In the current study, we have revealed that the 4-fluoro-N, N dimethylbenzenesulfonamide (FBSN) as an electrolyte additive can refrain the typical dehydrogenation of EC. Furthermore, a continuously repaired cathode electrolyte interphase (CEI) is designed elaborately on LiNi0.9Co0.05Mn0.05O2 (NCM90) surface by employing the FBSN as a sustained-release electrolyte additive to enhance cycling stability of NCM90||Li cells. This CEI, composed of high mechanical strength LiF and benzene ring skeleton, along with conductive Li+ moieties (S-rich and N-rich species), can be effectively self-repaired in time when damaged, reduce the interaction between the NCM90 and sensitive electrolyte, and mitigate the devastation to the NCM90 cathode surface. As a result, the NCM90||Li cells with 2 % FBSN-containing electrolyte delivers a capacity retention of 90.2 % after 200 cycles at 1C, and 83.1 % after 200 cycles even at higher voltage of 4.5 V, superior than that of Base electrolyte (70.0 % at 4.3 V and 68.0 % at 4.5 V). This study provides an engaging approach to design electrolytes for high-nickel cathodes by autonomously interfacial repair.