Fe3+-assistantly carbon-impregnated porous SiO2 mesoscale tubes as Li-ion battery anode materials with highly enhanced performances

Abstract

Porous SiO 2 mesoscale tubes (SiO 2 -pMT) impregnated with carbon in the pores within their tube walls were successfully prepared for the first time by making use of the Fe 3+ assisted anchoring of dopamine (DA) on the surface of SiO 2 as carbon source, and thereby endowed with highly enhanced anode performances for Li-ion batteries. Typically, a reversible specific capacity of 512.8 mAh g −1 was achieved after 500 cycles at 1 A g −1 when the SiO 2 -pMT impregnated with carbon by Fe 3+ assistance was used as anode material, which is about 10 times that of SiO 2 -pMT with no carbon impregnation and 25% higher than that of the SiO 2 -pMT with carbon impregnated at double the concentration of dopamine but in the absence of Fe 3+ cations. It has been found that the carbon impregnation of the SiO 2 -pMT may be achieved more easily and homogeneously with the assistance of Fe 3+ cations and, as a result, 3-dimensional porous carbon-networks with higher connectivity can be built up, which greatly facilitate the transport of electrons to more potential reaction sites where Li-ions are available and provide fast channel for Li-ions diffusion, leading to enhanced electrochemical kinetics, as unveiled by the differential capacity curves and electrochemical impedance spectra acquired at different intervals during the initial cycle. Furthermore, as shown by XPS data, such benefitial assistance of Fe 3+ cations is believed to arise from their coupling effects between the phenolic hydroxyl groups of dopamine molecules and the surface of SiO 2 through the chemical bondings of C-O-Fe and Fe-O-Si. Fe 3+ -assisted carbon impregnation of porous SiO 2 mesoscale tubes (SiO 2 -pMT) with dopamine as carbon source (via path 1) leading to remarkable enhancement in carbon content, structural homogeneity, and anode performance in Li-ion battery in contrast to that achieved with no Fe 3+ -assistance (via path 2). • Fe 3+ was firstly introduced into dopamine for the fabrication of SiO 2 -pMT@iC. • The carbon impregnation was achieved more homogeneously with the assistance of Fe 3+ . • The coupling effect of Fe 3+ exists through the chemical bonds of C-O-Fe and Fe-O-Si. • High connected porous carbon network enable SiO 2 -pMT@iC with enhanced performance.