C Fullerene-Reinforced Silicon Oxycarbide Composite Fiber Mats: Performance as Li-Ion Battery Electrodes.

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