C<sub>60</sub> Fullerene-Reinforced Silicon Oxycarbide\nComposite Fiber Mats: Performance as Li-Ion Battery Electrodes

Precursor-derived\nsilicon oxycarbide (SiOC) has emerged as a potential\nhigh-capacity anode material for rechargeable Li-ion batteries. The\npolymer processing and pyrolysis route, a hallmark of polymer-derived\nceramics, allows chemical interfacing with a variety of nanoprecursors\nand nanofiller phases to produce composites with low-dimensional structures\nsuch as fibers and coatings not readily attained in traditional sintered\nceramics. Here, buckminsterfullerene or C<sub>60</sub> was introduced\nas a filler phase in a hybrid precursor of 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane\n(TTCS) along with polyvinylpyrrolidone or PVP as a spinning agent\nto fabricate electrospun fiber mats, which upon a high-heat treatment\ntransformed to a C<sub>60</sub>-reinforced SiOC ceramic composite.\nTested as the self-supporting working electrode in a Li-ion half-cell,\nC<sub>60</sub>-reinforced fiber mats show a much-improved reversible\ncapacity (825 mA h g<sup>–1</sup>), nearly 100% Coulombic efficiency,\nand superior rate capability with low-capacity decay at high currents\n(only 25.5% decay at 800 mA g<sup>–1</sup>) compared to neat\nC<sub>60</sub> and neat carbonized fiber electrodes.