Carbon and RuO₂ Binary Surface Coating for the Li₃V₂(PO₄)₃ Cathode Material for Lithium-Ion Batteries

RuO2 nanocrystals are successfully impregnated into the surface carbon layer of the Li3V2(PO4)3/C cathode material by the precipitation method. Transmission electron microscopy shows that the RuO2 particles uniformly embed in the surface carbon layer. Cyclic voltammetry and electrochemical impedance spectroscopy indicate that the coexistence of carbon and RuO2 enables high conductivity for both Li ions and electrons and thus stabilizes the interfacial properties of the electrode, facilitates the charge transfer reactions, and improves the Li(+) diffusion in the electrode. As a result, the Li3V2(PO4)3 cathode coated with the binary surface layer shows improved rate capability and cycle stability. Particularly, the material containing 2.4 wt % Ru exhibits the best electrochemical performance and delivers a discharge capacity of 106 mAh g(-1) at the 10 C rate with a capacity retention of 98.4% after 100 cycles.