Malonic-acid-functionalized fullerene enables the interfacial stabilization of Ni-rich cathodes in lithium-ion batteries

High-capacity LiNi1-x-yCoxMnyO2 (NCM) (x + y <= 0.2) is a potential candidate for realizing high-energy-density lithium-ion batteries (LIBs). However, successful application of this cathode requires overcoming the irreversible phase transition (layered-to-spinel/rock-salt), interfacial instability caused by residual lithium compounds, and the electrolyte oxidation promoted by highly oxidized Ni-4(+). In this study, we investigate the roles of fullerene with malonic acid moieties (MA-C-60) as a superoxide dismutase mimetic (SODm) electrolyte additive in LIBs to deactivate reactive radical species (O-2(center dot-), LiOCO3 center dot, and Li(CO3)(2)(center dot)) induced by electrochemical oxidation of residual lithium compound, Li2CO3 on the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode surface and to scavenge trace water to avoid undesirable hydrolysis of LiPF6. Further, MA-C-60 maintains the structural stability of NCM811 cathodes and mitigates the parasitic reaction of residual lithium compounds with LiPF6 through the formation of a stable cathode-electrolyte interface. Our findings showed that MA-C-60 helps overcome the challenges associated with Li2CO3 oxidation at the NCM811 cathode, which produces CO2 gas and O-2(center dot-) that react with the solvent molecules.