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.

No abstract

Graphical AbstractCoFe2O4-graphene nanocomposites (CoFe2O4-GNSs) have been synthesized through an ultrasonic method combined with calcination process. The nanocomposite calcinated at 350 °C shows better rate capabilities, e.g., 696, 495, 308, and 254 mAh g−1 at 1, 2, 5, and 10 A g−1, respectively. Electronic supplementary materialThe online version of this article (doi:10.1007/s40820-014-0003-7) contains supplementary material, which is available to authorized users.

No abstract

SnO 2 nanorods/graphene nanosheets (GNSs) nanocomposites have been synthesized through a simple ultrasonic combined hydrothermal process, and the formation mechanism of the nanocomposites has been proposed. According to FESEM and TEM analysis, SnO 2 nanorods are directly grown and densely distributed on GNSs matrix in such a way that the structure of obtained nanocomposites is analogous to an array structure. The as-prepared nanocomposites exhibit a significantly improved lithium-storage capacity, good cycling stability and high rate capability, e.g. the reversible capacity is kept as high as 1107 mA h g À1 within 100 cycles at a current density of 200 mA g À1 , retaining 96.2% of the initial value. The high performance can be ascribed to the unique structure of SnO 2 nanorods/GNSs and the synergic effects of GNSs and SnO 2 nanorods, in which the direct growth of SnO 2 nanorods on GNSs can reduce the stacking of GNSs, provide more reaction sites and facilitate the rapid diffusion of electrons.

No abstract

Biomorphic SnO2/C composites were synthesized by a facile biotemplating method using natural cotton as the structure template and the bio-carbon source. The composites calcinated at 300 °C exhibited a reversible capacity of 530 mAh g−1 after 100 cycles at a current density of 100 mA g−1.

No abstract