LiNi1/3Co1/3Mn1/3O2-Graphene Composite as a Promising Cathode for Lithium-Ion Batteries

The use of graphene as a conductive additive to enhance the discharge capacity and rate capability of LiNi1/3Co1/3Mn1/3O2 electrode material has been demonstrated. LiNi1/3Co1/3Mn1/3O2 and its composite with graphene (90:10 wt %) were prepared by microemulsion and ball-milling techniques, respectively. The structural and morphological features of the prepared materials were investigated with powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Characterization techniques depict single-phase LiNi1/3Co1/3Mn1/3O2 with particle sizes in the range of 220-280 nm. Electrochemical studies on LiNi1/3Co1/3Mn1/3O2 and LiNi1/3Co1/3Mn1/3O2 graphene were conducted using cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy methods by constructing a lithium half-cell. Cyclic voltammograms show the well-defined redox peaks corresponding to Ni2+/Ni4+. Charge discharge tests were performed at different Crates: 0.05, 1, and 5 between 2.5 and 4.4 V. The results indicate the better electrochemical performance of the LiNi1/3Co1/3Mn1/3O2-graphene composite in terms of high discharge capacity(188 mAh/g), good rate capability, and good cycling performance compared to LiNi1/3Mn1/3Co1/3O2. The improved electrochemical performance of the LiNi1/3Co1/3Mn1/3O2-graphene composite is attributed to a decrease in the charge-transfer resistance.