Ni-rich LiNi0.8Co0.1Mn0.1O2 oxide functionalized by allyl phenyl sulfone as high-performance cathode material for lithium-ion batteries

Abstract

• Surface stability of Ni-rich Cathode is improved by using APS additive. • Electrochemical reaction of APS makes stable CEI layer on Ni-rich NCM surface. • APS-based CEI layer effectively suppresses decomposition of electrolytes. • The cell cycled with APS shows improved cycling performance at 45 °C. • NMR result exhibits APS effectively scavenge F – to prevent transition metal dissolution. Nickel-rich layered lithium metal oxides have been on the spotlight for their being advanced cathode materials for lithium-ion batteries; however, their poor cycling performance at high temperature is a critical bottleneck in their application. To improve the interfacial stability of Ni-rich layered lithium metal oxides, we propose the use of a functional electrolyte additive, allyl phenyl sulfone (APS), which is modified by allyl and sulfone functional groups. The sulfone functional group introduced into cathode–electrolyte interphases (CEI) is anticipated to effectively suppress electrolyte decomposition during cycling, whereas the allyl functional group renders the CEI more durable as its desirable chemical reactivity promotes additional crosslinking reaction between CEI. Additionally, the allyl functional group selectively scavenges fluoride (F − ) species in a cell and is thus is expected to reduce F − concentration, leading to the improved overall electrochemical performance of a cell. Results of ex-situ nuclear magnetic resonance spectroscopy confirmed that the APS additive effectively reduced the F − species via a chemical scavenging reaction. As regards the cycling performance of a half-cell, the cell cycled with the APS additive exhibited a considerably improved cycling retention at high temperature (78.9%), whereas the cell cycled with standard electrolyte suffered from continuous fading of retention (64.3%).