Amorphous Carbon-Coated Silicon Nanocomposites: A Low-Temperature Synthesis via Spray Pyrolysis and Their Application as High-Capacity Anodes for Lithium-Ion Batteries

Abstract

This article introduces an effective, inexpensive, and industrially oriented approach to produce carbon-coated Si nanocomposites as high-capacity anode materials for use in rechargeable lithium-ion batteries. Initially, nanosized Si particles (<100 nm) were mixed in a citric acid/ethanol solution via ultrasonication. This mixture was further spray-pyrolyzed in air at low processing temperature (300-500 °C), resulting in a homogeneous layer of carbon coating on the surface of the spheroidal Si nanoparticles. The effects of the processing temperature on the amorphous carbon content, the thickness of the carbon-coating layer, and the homogeneity of the carbon coating were studied in detail. These parameters strongly influenced the electrochemical performance of the carbon-coated Si nanocomposites, as will be discussed below. Carbon-coated Si nanocomposites spray-pyrolyzed in air at 400 °C show the best cycling performance, retaining a specific capacity of 1120 mA·h g^-1 beyond 100 cycles, with a capacity fading of less than 0.4% per cycle. The beneficial effect of the carbon coating in enhancing the dimensional stability of the Si nanoparticles appears to be the main reason for this markedly improved electrochemical performance.