Electrochemical lithium storage of a ZnFe2O4/graphene nanocomposite as an anode material for rechargeable lithium ion batteries

Abstract

In the present work, a graphene-based ZnFe₂O₄ nanocomposite has been synthesized using urea-assisted auto combustion synthesis followed by an annealing step. Urea synthesis is attractive, as it can rapidly synthesize materials with a high degree of control of particle size and morphology at low cost. The microstructure images clearly show that the ZnFe₂O₄ nanoparticles are homogeneously anchored on the surface of the graphene nanosheets. The average nanoparticle size ranges from 25–50 nm for both samples. As anode materials for lithium ion batteries, the obtained nanocomposite electrode shows significantly improved lithium storage properties with a high reversible capacity, excellent cycling stability and higher rate capability compared to the pure ZnFe₂O₄ nanoparticle electrode. The enhanced electrochemical performance of the nanocomposite sample can be attributed to the synergistic interaction between the uniformly dispersed ZnFe₂O₄ nanoparticles and the graphene nanosheets, which offers a large number of accessible active sites for the fast diffusion of Li⁺ ions, low internal resistance and more importantly accommodates the large volume expansion/contraction during cycling.