Manganese Dioxide Nanocomposite Preparation And Electrochemical Properties Of Di - Graphene

Lithium ion battery (LIB) was the most developed energy storage device for various applications such as portable electronic devices, electric vehicles, and sustainable energy generation systems because of their attractive high energy densities, no memory effect and high average output voltage compared with other energy storage techniques. However, first introduced in the commercial market as the anode material in LIBs, graphite has only a low specific capacity (372mAh g-1) and can hardly meet the increasing demand for higher energy density.One-dimensional (1-D) nanostructures have drawn continuous research attention because of their unique electrical, optical and magnetic properties different from that of bulk and nanoparticles as well as their potential applications in mesoscopic research and nanodevices. A variety of nanostructured transition-metal oxides have been widely investigated as anode materials for LIBs due to their high theoretical capacity, environmental benignity, non-formation of hazardous Li dendrites, and low cost. In particular, nanostructured manganese oxides have been widely investigated owing to their ideal electrochemical behavior, low cost, and environmental compatibility. Among them, manganese dioxide (MnO2) was one of the most stable manganese oxides with excellent physical and chemical properties under ambient conditions and was expected to be one of the ideal candidates as anode electrode material for LIB. However, as with other transition metal oxides, practical application of MnO2in LIBs was limited due to its huge volume expansion/contraction and particle polymerization during repeated cycling processes, which lead to electrode breakdown, decrease of inter-particle contact and poor cycling stability.Carbon-based composites have been exploited to solve these problems. Recently, graphene, one of the most popular nano-materials, has received considerable attention because of its superior conductivity, structure flexibility, large surface area, and chemical stability.In this present work, we used the conventional hydrothermal approach. However, we proved experimentally that instead of a two-step process, we could reduce the graphene oxide and synthesize the graphene-MnO2composite in a single step. Besides process simplification, we proved that this procedure also provides a simple and practical way to obtain a homogeneous network of MnO2nanowires with controllable size, shape and crystallinity covered with graphene. This nanostructured composite material was shown to exhibit superior electrochemical performance with large reversible capacity, high columbic efficiency, excellent cyclic performance and good rate capacity, showing a great potential and promise as anode material in LIBs.