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Title: Thermochemical energy storage using salt mixtures with improved hydration kinetics and cycling stability
Inorganic salt hydrates are promising materials for thermochemical energy storage as they undergo reversible solid-gas chemical reactions with water vapor to yield high energy densities with negligible self-discharge. However, material-level challenges such as structural and hygrothermal instabilities during the dehydration (charging) and hydration (discharging) reaction have limited their practical application in the buildings sector. The objective of this study is to address these irreversibilities in SrCl2 and MgCl2 by establishing a fabrication procedure that minimizes vapor diffusion resistance and lowers kinetic barriers for nucleation via particle size reduction. Furthermore, the distinct phase behavior of these two salts is leveraged to demonstrate a new binary salt mixture. Characterization of these materials was done using simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) with a humidity generator. The results demonstrate that ball milling to particle sizes <50 μm yields a structurally stable material with improved hydration kinetics, while a 50/50 mass ratio of the binary mixture extends the range of conditions for the hydration reaction. Importantly, the salt mixture achieves a high specific energy density of 1100 J g-1 and peak thermal power output of 1.4 W g-1 under conditions at which the individual salts either deliquesce (MgCl2) or do not fully/rapidly hydrate (SrCl2). This work provides a procedure for the standardized fabrication and rational design of thermochemical salt mixtures with complementary phase behavior.  more » « less
Award ID(s):
2238705
PAR ID:
10560131
Author(s) / Creator(s):
;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Journal of Energy Storage
Volume:
90
Issue:
PB
ISSN:
2352-152X
Page Range / eLocation ID:
111916
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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