Rigid-flexible free-standing multichannel carbon nanofiber-silicon composite anodes due to PS-induced channel ordering

Abstract

Silicon (Si)-carbon composite has been regarded as one of the most promising anodes for next-generation lithium-ion batteries (LIBs). However, low mechanical strength of carbon matrix is incapable of maintaining structural stability and electron/ion conductivity of Si anodes. Herein, we employ electrospinning-carbonization to construct free-standing Si@carbon nanofibers with internal ordered channels, uniformly distributed Si nanoparticles, and extraordinary elastic modulus (0.22 GPa) by introducing polystyrene as an oriented filler. The free-standing and rigid-flexible ordered multichannel carbon nanofibers (OM-CNFs) can absorb the volume variation of Si, effectively enhancing the mechanical strength and chemical stability of electrodes. The Si nanoparticles uniformly embedded into the highly conductive OM-CNFs matrix establish a bicontinuous structure and increase the contact area between Si and CNFs, thus boosting the rate capability. Consequently, the Si@OM-CNFs anode delivers an excellent reversible capacity of 939.9 mA h g−1 even at 5 A g−1 after 300 cycles. The assembled full-cell with a prelithiated Si@OM-CNFs anode and LiFePO4 cathode delivers a high energy density of 341 Wh kg−1. This work provides insights into the design of high mechanical strength Si/C composite anodes for high-performance LIBs.