Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.

Issue 26, 2020
Previous Article Next Article

Tunable LiCl@UiO-66 composites for water sorption-based heat transformation applications

Author affiliations


Porous composite materials are potential candidates for water-based adsorptive heat transformation (AHT) applications. Here, a solid adsorbent LiCl@UiO-66 as a 'composite salt inside porous matrix’ (CSPM) has been prepared by incorporating hygroscopic lithium chloride into a microporous metal–organic framework (MOF) UiO-66 as a host matrix through the wet impregnation method. In our wet impregnation we did not let the excess salt solution dry to prevent salt precipitation on the matrix surface. This yielded a true salt@MOF composite with no deliquescence of LiCl and strongly enhanced the water adsorption capacity of UiO-66 through the salt content. At p/p0 = 0.1 the water vapor sorption isotherms show a hydration state of LiCl inside the MOF of LiCl·2–4H2O which is much higher than for neat LiCl with 0.5H2O, due to the dispersion of a small particle size inside the matrix. LiCl@UiO-66 with a 30 wt% LiCl content (LiCl@UiO-66_30) has a 3 to 8 times higher water uptake over neat UiO-66 (depending on relative pressure) and could reach a volumetric and gravimetric water uptake of over 2.15 g g−1 at p/p0 = 0.9, which outperforms the so far known UiO-66-based composites. Cycling tests confirmed the hydrothermal stability of the LiCl@UiO-66 composites. Kinetic evaluation of the gravimetric water uptake (at 90% relative humidity) over time yielded rate coefficients up to 2.0(1) × 10−4 s−1 which is slower than that in neat UiO-66 (6.7(6) × 10−4 s−1) but faster than that for salt@silica gel composites. The coefficient of performance for the heat pumping mode (at Tdes/Tads/Tevap set to 90/40/10 °C) of 1.64 for LiCl@UiO-66_30 exceeds those of other MOFs, salt@MOF or salt@silica gel composites. For thermal battery applications the heat storage capacity (CHS) for LiCl@UiO-66_30 is 900 kJ kg−1 (=0.25 kW h kg−1), which can reach the Department of Energy (DOE) value of 2.5 kW h/35 kg with just 10 kg of material and outperforms CaCl2@UiO-66_38 with a CHS value of 367 kJ kg−1.

Graphical abstract: Tunable LiCl@UiO-66 composites for water sorption-based heat transformation applications

Back to tab navigation

Supplementary files

Article information

27 Mar 2020
12 Jun 2020
First published
12 Jun 2020

J. Mater. Chem. A, 2020,8, 13364-13375
Article type

Tunable LiCl@UiO-66 composites for water sorption-based heat transformation applications

Y. Sun, A. Spieß, C. Jansen, A. Nuhnen, S. Gökpinar, R. Wiedey, S. Ernst and C. Janiak, J. Mater. Chem. A, 2020, 8, 13364
DOI: 10.1039/D0TA03442H

Social activity

Search articles by author