Sequential-template synthesis of hollowed carbon polyhedron@SiC@Si for lithium-ion battery with high capacity and electrochemical stability

摘要

In this work, we propose a sequential-template method to synthesize hollowed carbon polyhedron@silicon carbide@silicon (HCP@SiC@Si) tandem architecture as high-performance lithium ion batteries' (LIBs) anode. The ZIF-8@SiO2 Yolk-shell precursor is prepared by the in-situ synthesis of SiO2 film on ZIF-8 where ZIF-8 is etched by Si(OH)(4) simultaneously, and the following magnesium thermal reduction treatment results in the formation of HCP@SiC@Si. The HCP@SiC@Si is composed of a carbon inner-shell, SiC interlayer and Si nanoflakes outer-layer, realizing a novel nanostructure. As a result, the HCP@SiC@Si anode with highly-crystalized SiC interlayer exhibits good initial discharge capacity of 748.2 mAh g(-1) with Coulombic efficiency of 98.06% at the current density of 0.1 A g(-1). Further, the reversible capacity tends to stabilize at 816.3 mAh g(-1) after 100 cycles. Even the current density reaches to 1.0 A g(-1), a highly reversible capacity of 218 mAh g(-1) after 200 cycles can be achieved. Beyond that, the structure of HCP@SiC@Si maintains very well after withstanding long cycling. These results suggest that this tandem structure promotes the kinetics for lithiation/de-lithiation and diffusion process. Meanwhile, the significance of SiC with high crystallinity on the improved LIB's performance of HCP@SiC@Si is highlighted as well.