Hydrated Salt/Graphite/Polyelectrolyte Organic-Inorganic Hybrids for Efficient Thermochemical Storage.

Sergio Salviati,Alberto Fina,Guido Saracco,Federico Carosio

doi:10.3390/nano9030420

Abstract

Hydrated salt thermochemical energy storage (TES) is a promising technology for high density energy storage, in principle opening the way for applications in seasonal storage. However, severe limitations are affecting large scale applications, related to their poor thermal and mechanical stability on hydration/dehydration cycling. In this paper, we report the preparation and characterization of composite materials manufactured with a wet impregnation method using strontium bromide hexahydrate (SBH) as a thermochemical storage material, combined with expanded natural graphite (G). In addition to these fully inorganic formulations, an organic polyelectrolyte (PDAC, polydiallyldimethylammonium chloride) was exploited in the structure, with the aim to stabilize the salt, while contributing to the sorption/desorption process. Different formulations were prepared with varying PDAC concentration to study its contribution to material morphology, by electron microscopy and X-ray diffraction, as well as water sorption/desorption properties, by thermogravimetry and differential calorimetry. Furthermore, the SBH/G/PDAC powder mixture was pressed to form tabs that were analyzed in a climatic chamber, which is evidence for an active role of PDAC in the improvement of water sorption, coupled with a significant enhancement of mechanical resistance upon hydration/dehydration cycling. Therefore, the addition of the polyelectrolyte is proposed as an innovative approach in the fabrication of efficient and durable TES devices.

Highlights

Fighting climate change is one of the biggest challenges, attracting research efforts from all over the world
The increasing development of renewable energy sources creates the need to reinvent energy demand management resulting in integrated solutions where thermal energy storage (TES) technologies are coupled with photovoltaic panels and/or solar thermal technologies in order to manage the peak of electricity demand and reduce the costs related to electricity consumption [9,10]
Despite the selection of the hydrated salt primarily depending on the available source temperature, one of the most promising thermochemical materials (TCMs) discussed in literature for low temperature TES applications is SrBr2·6H2O (SBH) owing to its effective combination of a relatively high storage density (798 kJ/kg) and low dehydration temperature ( 100 ◦C) as reviewed in a detailed study [19]

Summary

Introduction

Fighting climate change is one of the biggest challenges, attracting research efforts from all over the world. The second important advantage of TCMs over PCMs is the higher (one order of magnitude) energy storage density associated with the employed materials [14] Due to this great potential, many efforts were made to identify the best performing salt hydrates with both experimental [15,16], and theoretical methods [17,18]. Despite the selection of the hydrated salt primarily depending on the available source temperature, one of the most promising TCMs discussed in literature for low temperature TES applications is SrBr2·6H2O (SBH) owing to its effective combination of a relatively high storage density (798 kJ/kg) and low dehydration temperature ( 100 ◦C) as reviewed in a detailed study [19].

Characterization

Morphology Analysis

Conclusions