Ab-initio study of doped salt hydrates crystal stabilities for thermochemical heat storage

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

Abstract

In order to move towards a sustainable energy economy, a reliable energy storage technology is necessary. Thermochemical heat storage based on reversible physico-chemical processes, like sorption of water in hygroscopic chloride-based salts, is a highly appealing approach. This concept allows one to store heat over long periods of time in relative compact systems. Promising materials for this process are MgCl2·nH2O and CaCl2·nH2O (n=0,1,2,4,6), which undergo chemical reactions between the different hydrates at the desired operating temperatures. However, challenges remain related to the kinetics and stability of these salt hydrates. Another challenge is the formation of HCl through hydrolysis of MgCl2·nH2O at high temperatures. Doped salts have the potential to overcome these challenges. Therefore, density functional theory (DFT) studies are performed on MgCl2·2H2O with varying contents of Ca, and on CaCl2·2H2O with varying contents of Mg. Advanced chemical bonding approaches (DDEC6 bond order and charges, Bader topological analysis) are used to describe the relevant chemical bonds within these doped structure. These tools allow to quantitatively and qualitatively describe the doped crystals, and provide insight in the strength and nature of its interatomic interactions. Important trends in structure stability of the doped salts are revealed. It is confirmed that doping MgCl2·nH2O increases its resistivity towards hydrolysis. However, too high amount of doping (above 39%), can result in metastable crystal structures.
LanguageEnglish
Title of host publicationEurotherm Seminar #112 Advances in Thermal Energy Storage
Number of pages10
ISBN (Electronic)978-84-9144-155-7
StatePublished - Jun 2019
EventEurotherm Seminar #112: Advances in Thermal Energy Storage - University of Lleida, Lleida, Spain
Duration: 15 May 201917 May 2019
http://eurotherm.udl.cat/#Home

Conference

ConferenceEurotherm Seminar #112
CountrySpain
CityLleida
Period15/05/1917/05/19
Internet address

Fingerprint

Magnesium Chloride
Heat storage
Hydrates
Salts
Crystals
Hydrolysis
Doping (additives)
Chemical bonds
Energy storage
Density functional theory
Sorption
Chlorides
Chemical reactions
Crystal structure
Temperature
Kinetics
Water

Keywords

  • Thermochemical heat storage
  • doped salts
  • salt hydrates
  • Chemical bonding analysis

Cite this

@inproceedings{fa2e5a9f0aa444158869bc4c56e56602,
title = "Ab-initio study of doped salt hydrates crystal stabilities for thermochemical heat storage",
abstract = "In order to move towards a sustainable energy economy, a reliable energy storage technology is necessary. Thermochemical heat storage based on reversible physico-chemical processes, like sorption of water in hygroscopic chloride-based salts, is a highly appealing approach. This concept allows one to store heat over long periods of time in relative compact systems. Promising materials for this process are MgCl2·nH2O and CaCl2·nH2O (n=0,1,2,4,6), which undergo chemical reactions between the different hydrates at the desired operating temperatures. However, challenges remain related to the kinetics and stability of these salt hydrates. Another challenge is the formation of HCl through hydrolysis of MgCl2·nH2O at high temperatures. Doped salts have the potential to overcome these challenges. Therefore, density functional theory (DFT) studies are performed on MgCl2·2H2O with varying contents of Ca, and on CaCl2·2H2O with varying contents of Mg. Advanced chemical bonding approaches (DDEC6 bond order and charges, Bader topological analysis) are used to describe the relevant chemical bonds within these doped structure. These tools allow to quantitatively and qualitatively describe the doped crystals, and provide insight in the strength and nature of its interatomic interactions. Important trends in structure stability of the doped salts are revealed. It is confirmed that doping MgCl2·nH2O increases its resistivity towards hydrolysis. However, too high amount of doping (above 39{\%}), can result in metastable crystal structures.",
keywords = "Thermochemical heat storage, doped salts, salt hydrates, Chemical bonding analysis",
author = "Koen Heijmans and Ionut Tranca and {Gaastra - Nedea}, Silvia and David Smeulders",
year = "2019",
month = "6",
language = "English",
booktitle = "Eurotherm Seminar #112 Advances in Thermal Energy Storage",

}

Heijmans, K, Tranca, I, Gaastra - Nedea, S & Smeulders, D 2019, Ab-initio study of doped salt hydrates crystal stabilities for thermochemical heat storage. in Eurotherm Seminar #112 Advances in Thermal Energy Storage., E150, Eurotherm Seminar #112, Lleida, Spain, 15/05/19.

Ab-initio study of doped salt hydrates crystal stabilities for thermochemical heat storage. / Heijmans, Koen; Tranca, Ionut; Gaastra - Nedea, Silvia; Smeulders, David.

Eurotherm Seminar #112 Advances in Thermal Energy Storage. 2019. E150.

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

TY - GEN

T1 - Ab-initio study of doped salt hydrates crystal stabilities for thermochemical heat storage

AU - Heijmans,Koen

AU - Tranca,Ionut

AU - Gaastra - Nedea,Silvia

AU - Smeulders,David

PY - 2019/6

Y1 - 2019/6

N2 - In order to move towards a sustainable energy economy, a reliable energy storage technology is necessary. Thermochemical heat storage based on reversible physico-chemical processes, like sorption of water in hygroscopic chloride-based salts, is a highly appealing approach. This concept allows one to store heat over long periods of time in relative compact systems. Promising materials for this process are MgCl2·nH2O and CaCl2·nH2O (n=0,1,2,4,6), which undergo chemical reactions between the different hydrates at the desired operating temperatures. However, challenges remain related to the kinetics and stability of these salt hydrates. Another challenge is the formation of HCl through hydrolysis of MgCl2·nH2O at high temperatures. Doped salts have the potential to overcome these challenges. Therefore, density functional theory (DFT) studies are performed on MgCl2·2H2O with varying contents of Ca, and on CaCl2·2H2O with varying contents of Mg. Advanced chemical bonding approaches (DDEC6 bond order and charges, Bader topological analysis) are used to describe the relevant chemical bonds within these doped structure. These tools allow to quantitatively and qualitatively describe the doped crystals, and provide insight in the strength and nature of its interatomic interactions. Important trends in structure stability of the doped salts are revealed. It is confirmed that doping MgCl2·nH2O increases its resistivity towards hydrolysis. However, too high amount of doping (above 39%), can result in metastable crystal structures.

AB - In order to move towards a sustainable energy economy, a reliable energy storage technology is necessary. Thermochemical heat storage based on reversible physico-chemical processes, like sorption of water in hygroscopic chloride-based salts, is a highly appealing approach. This concept allows one to store heat over long periods of time in relative compact systems. Promising materials for this process are MgCl2·nH2O and CaCl2·nH2O (n=0,1,2,4,6), which undergo chemical reactions between the different hydrates at the desired operating temperatures. However, challenges remain related to the kinetics and stability of these salt hydrates. Another challenge is the formation of HCl through hydrolysis of MgCl2·nH2O at high temperatures. Doped salts have the potential to overcome these challenges. Therefore, density functional theory (DFT) studies are performed on MgCl2·2H2O with varying contents of Ca, and on CaCl2·2H2O with varying contents of Mg. Advanced chemical bonding approaches (DDEC6 bond order and charges, Bader topological analysis) are used to describe the relevant chemical bonds within these doped structure. These tools allow to quantitatively and qualitatively describe the doped crystals, and provide insight in the strength and nature of its interatomic interactions. Important trends in structure stability of the doped salts are revealed. It is confirmed that doping MgCl2·nH2O increases its resistivity towards hydrolysis. However, too high amount of doping (above 39%), can result in metastable crystal structures.

KW - Thermochemical heat storage

KW - doped salts

KW - salt hydrates

KW - Chemical bonding analysis

M3 - Conference contribution

BT - Eurotherm Seminar #112 Advances in Thermal Energy Storage

ER -