Freestanding silicon/carbon nanofibers composite membrane as a flexible anode for Li-Ion battery

A flexible freestanding Si/Carbon nanofibers composite membrane with high mechanical strength is prepared by electrospinning and chemical vapor deposition techniques. The physical characteristics of Si/Carbon nanofibers are characterized by scanning electron microscopy, thermo-gravimetric analysis, X-ray diffraction and transmission electron microscopy. The electrochemical performances are investigated by galvanostatic charge-discharge tests and cyclic voltammograms. Carbon nanofibers matrix shows uniform diameter, smooth surface and three dimensional network structures. Si shell with a thickness of 50 nm is uniformly deposited on the surface of carbon nanofibers. The as-synthesized Si/Carbon nanofibers anode delivers 1310 mAh g−1 at 2nd cycle and the loss rate of capacity per cycle is as lower as 0.0703% from 2nd to 480th cycles, which exhibits excellent electrochemical performance. It demonstrates that the structure of three dimensional network membrane that has played an important role in alleviating volume expansion-contraction of Si-based anodes during charge-discharge process.