Graphene-metal oxide composite as anode material in li-ion batteries

Lithium ion batteries (LIBs) have drawn considerable attention in physics/materials science, chemistry/ chemical engineering, and computational chemistry, as well as in industries. Owing to its outstanding properties such as superior energy density, good cycle life, high operating voltage, and wide working temperature range, LIBs have applications in consumer electronic devices and electric/ hybrid vehicles. The low theoretical capacity (372 mAh g^-1) of the currently used graphite anode limits its applications in higher-capacity devices. Metal oxide (MO) has been pursued previously to overcome the issues related to the specific capacity, but the low conductivity and capacity fading due to severe volume expansion are some of the major limitations for future applications in LIBs. Recently, graphene-metal oxide (MO) composite has attracted huge attention among researchers because of its synergistic effects, where graphene/reduced graphene oxide (rGO) can work as an excellent conducting layer for better charge transport and strong adhesion of the MO with the oxygen functional groups of graphene/rGO. Although graphene has high surface area with excellent electrical conductivity, graphene sheets usually aggregate, reducing the overall surface area as well as the properties. MO nanoparticles/nanostructures grow on/attach to the graphene/rGO sheets, preventing the aggregation of the graphene sheets to improve capacity, cyclic stability, and rate capability of the anode materials. Porous graphene and the MO composite are new concepts, and several researches have also been carried out to enhance the capacity of the anode materials. In this book chapter, we describe different methods for the synthesis of graphene-MO/porous graphene-MO composites, their microstructure, bond vibrations/binding energies, thermal studies, and electrochemical properties, and we will also compare all the available data with the results obtained by our graphene/rGO-MO composite. In this book chapter, we first introduce the basics of LIBs followed by the use of metal oxide and the graphene-metal oxide composite as anode in LIBs.