SMALL-ANGLE X-RAY SCATTERING STUDIES OF NANOSTRUCTURED RESPIRATOR AND BATTERY MATERIALS

Abstract

This work represents a small-angle X-ray scattering (SAXS) investigation into the structure of two rather different materials: chemically impregnated activated carbons (IACs) and the nanostructured alloy of tin-cobalt-carbon. Five impregnant species, namely sodium benzoate, potassium biphthalate, zinc chloride, potassium carbonate, and silver nitrate, were impregnated into activated carbon using the incipient wetness or imbibing method to various loadings and examined. Using a modified version of the Kalliat model and a suitable interpretation, two different impregnant behaviours arose: one marked by good chemical dispersion over all classes of carbon pores, the other characterized by a formation of large grains but little deposition in micropores or formation of small grains. A special apparatus was constructed to collect SAXS data of Li-ion coin cells with beryllium windows using a nanostructured SnCoC electrode. When one such cell was charged and discharged, the entry and exit of lithium atoms into the SnCoC material caused structural deformations, which were visible in SAXS data through the use of the modified Kalliat model. The size of the SnCo grains changed as lithium was inserted and removed from the SnCoC electrode. However, when the cell voltage was less than 0.2 V the SnCo grain size was constant, suggesting lithium insertion and removal below 0.2 V was occurring in the carbon matrix.