Effect of carbon nanospace on charge-discharge properties of Si and SiOx nanoparticles-embedded nanoporous carbons

Abstract

Providing both electronic conduction paths and buffer space for the large volume change between LixSi and Si are considered to be the key of development of high-performance Si-based anodes. Si and SiOx nanoparticle-embedded nanoporous carbons were synthesized by Mg thermal reduction of a SiO2 opal-carbon nanocomposite precursor followed by HCl and HF treatments, and the interstitial space in carbon nanopores was systematically controlled by NaOH-etching of the precursor. The electrochemical charge-discharge capacity and its retention with cycling of obtained samples were increased with increasing the nanopore volume and decreasing the loading amount of active material per pore volume. It was also found that dispersive loading of Si and SiOx nanoparticles in the carbon nanospace enhances the reactivity of Si and SiOx nanoparticles. The relationship between the composite structure and the charge-discharge properties were discussed in detail.