Improved kinetics of LiNi1/3Mn1/3Co1/3O2 cathode material through reduced graphene oxide networks

An electronically conducting 3D network of reduced graphene oxide (RGO) was introduced into LiNi1/3Mn1/3Co1/3O2 (LNMC) cathode material in a special nano/micro hierarchical structure. The rate test and cycling measurement showed that the hierarchical networks remarkably improve the high rate performance of LNMC electrode for lithium-ion batteries. The effect of RGO conducting networks on kinetic property was investigated by electrochemical impedance spectroscopy (EIS) and potentiostatic intermittent titration (PITT). The EIS results reveal that the RGO network greatly decreases the resistance of lithium batteries, especially the charge transfer resistance which can be attributed to the significantly improved conducting networks. The enhancement of apparent diffusion coefficient by the RGO conducting networks is shown by PITT. The power performance was found to be limited by the electrical conduction in the two-phase region, which can be greatly facilitated by the hierarchical RGO network together with carbon black. The as-obtained LNMC/RGO cathode exhibits an outstanding electrochemical property supporting the design idea of electronically conducting 3D networks for the high-energy and high-power lithium-ion batteries.