Si nanoparticles embedded in porous N-doped carbon fibers as a binder-free and flexible anode for high-performance lithium-ion batteries

Abstract

Si has attracted more attention as an ideal anode for next-generation Li-ion batteries (LIBs), due to its large theoretical capacity and low de-lithiation voltage. However, extreme volume change (about 300%) and low electronic conductivity severely hinder its practical application. Herein, to overcome these problems, via the electrospinning and pyrolysis processes, Si nanoparticles are embedded in porous N-doped carbon fibers (Si/P-NCFs) and interwoven into a flexible film. The binder-free and flexible Si/P-NCFs can significantly enhance the Li-ion storage capacity (1386 mAh g−1 after 100 cycles at 0.1 A g–1), cycling stability (942 mAh g−1 over 1000 cycles at 1 A g−1), as well as rate capability (381 mAh g−1 at 10 A g−1). These improvements are ascribed to the spatial confinement of carbon fibers and buffering effect of porous structure, which synergistically prevent the harm caused by the volume change. Additionally, porous N-doped carbon networks and binder-free structure can significantly enhance electron/ion conductivities. This work demonstrates an effective design to address the volume change and low electronic conductivity of Si towards advanced flexible Si-based anodes, as well as exhibits promising potential in practical use.