High crystalline carbon network of Si/C nanofibers obtained from the embedded pitch and its contribution to Li ion kinetics

Silicon (Si) has attracted much attention as a promising anode material for Li ion battery because of its high theoretical specific capacity and low working potential. However, Si has shown poor cycling behavior and reversibility, which result from its huge volume change and the following pulverization. In this study, an electrospinning method was adopted to synthesize Pitch-incorporated into Si/Carbon nanofibers (Si/Pitch CNFs), which has high crystalline carbon network compared to other Si/Carbon nanofibers without the carbon matrix obtained from the decomposition of pitch. We demonstrated that this high crystalline carbon network in the form of nanofiber has two kinds of merits: it not only reduced the diffusion length for Li ion transport thanks to its 1D morphology but also helped to tolerate high strain of Si and maintain electron transport throughout the entire electrode. As a result, Si/Pitch CNFs showed a greatly enhanced kinetic performance, even at 10C, thus showing its feasibility as a high-power material for future applications like electric vehicles (EV) and energy storage systems (ESS).