▎ 摘　　要

Spinel LiNi0.5Mn1.5O4 (LNMO) has been considered as one of the most promising candidate cathode materials for power lithium-ion batteries. However, its cycle performance suffers from the increasing impedance of the LNMO-cathode/electrolyte interface (LNMO-CEI) layer caused by parasitic reactions on the electrode surface at high operating potentials. To address the capacity degradation upon cycling, we present a feasible way to realize electrode modification by electrophoretically deposited graphene ultrathin films on the exterior surface of the LNMO cathodes without decreasing the electrode density. A p-phenylene diamine reduced graphene oxide (pPD-rGO) film with an area density of 20 mu g/cm(2) not only increases the capacity retention rate of the 1000th cycle at 4.2-5.2 V from 71.7 to 81.7% but also boosts the specific capacity from 110.6 to 122.4 mAh/g. X-ray photoelectron spectroscopy (XPS) spectra reveal that the pPD-rGO film with Lewis-base nature increases the content of LiF and reduces the number of RCFx groups in the cycled electrode, indicating the consumption of high-potential-generated F radicals by the pPD-rGO film. Such consumption favors the formation of a robust interphase between the pPD-rGO film and the electrolyte, which could hinder the sustained production of F radicals, consequently stabilize the LNMO-CEI layer, and improve the cycle performance. An electrophoretically deposited Lewis-acid GO film of 20 mu g/cm(2) reduces the specific capacity and fails to work as the pPD-rGO film. The chemical process for the formation of interphase on the GO film is similar to that on the bare LNMO electrode.