Solvothermal hybridization of LiMn1/3Ni1/3Co1/3O2 and reduced graphene oxide to promote lithium-ion cathode performance

Abstract

A facile solvothermal solution has been introduced to hybridize pre-sintered LiMn_1/3Ni_1/3Co_1/3O₂ (LMNC) nanocrystals and ethylene glycol reduced graphene oxide (EGRGO) nanosheets. Compared with the liquid-based growth of metallic oxide on graphene sheets, this approach not only ensures a high crystallinity of the LMNC particles from pre-sintering, but also realizes the intimate coupling of RGO with LMNC via covalent metal–oxygen bonds. The as-prepared EGRGO/LMNC nanocomposites have been characterized and confirmed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The fabricated EGRGO/LMNC composite electrodes have been investigated using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The results reveal the markedly improved reversibility of the EGRGO/LMNC cathode toward lithium ion intercalation/extraction, which results in a large discharge capacity, high coulombic efficiency, and excellent rate performance. The elevated electrochemical capability of the EGRGO/LMNC cathode material is accounted for the better electrical conduction of the EGRGO nanosheets, highly stable crystal structure of the pre-sintered LMNC particles, and firm construction of the EGRGO/LMNC composite due to solvothermal hybridization.