The study on nanostructural evolution of SnO2-carbon aerogel nanocomposite during the first discharge process

Abstract

SnO2 has attracted great attention at energy storage due to the high capacity. The electrochemical conversion behavior of SnO2 as well as its influence on the lithium-storage performance remains unclear because of its pulverization and aggregation. In this paper, SnO2-carbon aerogel (CA) composites were characterized by TEM, SEM, XRD, XPS, FTIR, TG/DTG and BET. SnO2-CA anode materials exhibit excellent cycling stability and a strong rate capacity. The nanostructural evolution of SnO2-CA as anode material were studied by in situ electrochemical-grazing incidence small angle X-ray scattering (GISAXS) technique. The GISAXS results demonstrate that the multihierarchical scatterers in the SnO2-CA as anode material can be roughly divided into interspace, SnO2 nanoparticles, nanopores and so on during the first lithiation. The nanostructural evolution of SnO2 nanoparticles are observed and subsequently some cracks occur that result from the existence of tension stress during the first discharge process. At the same time, the volumes of interspaces and nanopores also expand slightly during Li-ion intercalation process. A schematic model has been tentatively proposed to describe the first lithiation of SnO2-CA anode. It is firmly believed that these results will help further understanding of the complicated reaction mechanism of nanostructured Sn-based anode materials and provide a valuable insight into designing new electrode materials.