MORPHOLOGICAL AND STRUCTURAL EVALUATION OF AD/DESORPTION STAGES OF SORBENT LiCl COMPOSITES FOR THERMAL ENERGY STORAGE

The aim of the present work is the definition of a characterization protocol for the morphological and structural evaluation of an advanced sorbent composite. The innovative material, based on LiCl supported on multiwall carbon nanotubes (MWCNT) and bent with PolyVinilAlkohol (PVA) as a binder, was specifically developed for sorption thermal energy storage (TES) applications. The composite sorbent was synthesized through a dry impregnation. The phase composition of the composite and its transformation during the ad/desorption cycling were studied. Particularly, the synthesized samples were characterized by temperature programmed X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) operating under controlled humidity and temperature conditions. Isotherms of water vapor sorption were measured by a thermogravimetric technique on an automated vapor sorption analyzer. During water sorption, a morphological transformation due to hydration of LiCl towards crystalline hydrate LiCl∙H2O occurred. The crystalline hydrate LiCl∙H2O formation is likely to be a reason of the water adsorption/desorption hysteresis observed for the sorbent composite.