Nano-to-Microdesign of Marimo-Like Carbon Nanotubes Supported Frameworks via In-spaced Polymerization for High Performance Silicon Lithium Ion Battery Anodes

Silicon (Si) has been perceived as a promising anode material for lithium-ion batteries for decades due to its superior theoretical capacity, environmental benignity, and earth abundance. To accommodate the drastic volume expansion during lithiation, which is the primary drawback leading to poor cycling life, a novel structural design via fabricating the Marimo-like carbon nanotubes frameworks with silicon nanoparticle (SiNP) filling in internal space has been developed. This facile fabrication procedure involves an in-spaced polymerization process through ex situ polymerization, using pyrrole monomers with a soft organic template in which well-dispersed SiNPs are present. Carbonization post-treatment is then performed to construct rigid conductive networks. The thus-fabricated 3D Marimo-like hybrid structure exhibits a remarkably improved electrochemical performance compared with that of the simple ball-milling method, which mainly originates from their structural advantages, including the built-in buffer spaces and the robust line-to-line contact mode between the components. The state-of-the-art structure exhibits an optimal high-rate capability (422 mAh g(-1) at a current rate of 2 A g(-1)) and long cycling stability (916 mAh g(-1) for 200th cycles at a current rate of 0.2 A g(-1)) and achieves the requirements for industrial production with the facile and cost-effective synthetic approach.