High-capacity Li-rich layered oxide cathodes along with Si-incorporated graphite anodes have high reversible capacity, outperforming the electrode materials used in existing commercial products. Hence, they are potential candidates for the development of high-energy-density lithium-ion batteries (LIBs). However, structural degradation induced by loss of interfacial stability is a roadblock to their practical use. Here, the use of malonic acid-decorated fullerene (MA-C-60) with superoxide dismutase activity and water scavenging capability as an electrolyte additive to overcome the structural instability of high-capacity electrodes that hampers the battery quality is reported. Deactivation of PF5 by water scavenging leads to the long-term stability of the interfacial structures of electrodes. Moreover, an MA-C-60-added electrolyte deactivates the reactive oxygen species and constructs an electrochemically robust cathode-electrolyte interface for Li-rich cathodes. This work paves the way for new possibilities in the design of electrolyte additives by eliminating undesirable reactive substances and tuning the interfacial structures of high-capacity electrodes in LIBs.