MnFe2O4-graphene nanocomposites with enhanced performances as anode materials for Li-ion batteries.

MnFe(2)O(4)-graphene nanocomposites (MnFe(2)O(4)-GNSs) with enhanced electrochemical performances have been successfully prepared through an ultrasonic method, e.g., approximate 1017 mA h g(-1) and 767 mA h g(-1) reversible capacities are retained even after 90 cycles at a current density of 0.1 A g(-1) and 1 A g(-1), respectively. The remarkable improvement in the reversible capacity, cyclic stability and rate capability of the obtained MnFe(2)O(4)-GNSs nanocomposites can be attributed to the good electrical conductivity and special structure of the graphene nanosheets. On the other hand, MnFe(2)O(4) also plays an important role because it transforms into a nanosized hybrid of Fe(3)O(4)-MnO with a particle size of about 20 nm during discharge-charge process, and the in situ formed hybrid of Fe(3)O(4)-MnO can be combined with GNSs to form a spongy porous structure. Furthermore, the formed hybrid can also act as the matrix of MnO or Fe(3)O(4) to prevent the aggregation of Fe(3)O(4) or MnO, and accommodate the volume change of the active materials during the discharge-charge processes, which is also beneficial to improve the electrochemical performances of the MnFe(2)O(4)-GNSs nanocomposites.