Free-standing and flexible CNT/(Fe@Si@SiO2) composite anodes with kernel-pulp-skin nanostructure for high-performance lithium-ion batteries

Abstract

Silicon-based anodes with carbon materials as current collectors are promising for the fabrication of flexible lithium-ion batteries with high energy density due to the high specific capacity of silicon as well as the light weight and excellent flexibility of carbon materials. Currently it is still significant and challenging to develop new preparation methods and electrode structures to achieve the combination of low cost and high performance for such anodes. In this work, we report a simple and scalable method to prepare freestanding and flexible CNT/(Fe@Si@SiO2) composite anodes with novel kernel-pulp-skin nanostructure for lithium-ion batteries. This unique kernel-pulp-skin nanostructure facilitates the charge transfer at the electrolyte/electrode interface and the diffusion of lithium in the electrode material, which significantly improves the cycle stability and rate capability of the electrode. The resultant CNT/(Fe@Si@SiO2) composite anodes exhibit a high reversible capacity (968 mAh g−1 at 1 A g−1) and stable cycling performance with a capacity retention of 83% after 500 cycles.