Combustion synthesis of MgFe2O4/graphene nanocomposite as a high-performance negative electrode for lithium ion batteries

We present a facile and cost-effective urea-assisted auto-combustion method for synthesizing pure MgFe2O4 nanoparticle and MgFe2O4/graphene nanocomposite samples followed by annealing at 600 °C for 5 h under N2 atmosphere. The X-ray diffraction pattern confirmed the single phase formation for both samples. The obtained morphology of the nanocomposite sample shows that the MgFe2O4 nanoparticles are highly dispersed on conductive graphene nanosheets with particle size in the range of 50–100 nm. When applied as an anode material, MgFe2O4/graphene nanocomposite electrode shows a high reversible charge capacity of 764.4 mAh g− 1 at 0.04 C over 60 charge/discharge cycles and in spite of that it also retained a capacity of 219.9 mAh g− 1 at high current rate of 4.2 C. The obtained result is much better than the synthesized pure MgFe2O4 nanoparticle electrode. The excellent electrochemical performance of the MgFe2O4/graphene nanocomposite electrode can be attributed to the strong favorable synergistic interaction between MgFe2O4 and reduced graphene nanosheets, which supplied a large number of accessible active sites for Li+-ion insertion and short diffusion length for both Li+ ions and electrons. In addition, the graphene nanosheets in the nanocomposite electrode provide high conductivity and accommodate the large volume expansion/contraction during cycling, resulting in high capacity and long cycling stability.