Title: The favourable thermodynamic properties of Fe-doped CaMnO ₃ for thermochemical heat storage

Abstract

The CaMnO₃ oxide can reversibly release oxygen over a relatively wide range of temperatures and oxygen partial pressures (pO₂) and is thus a promising candidate for thermochemical heat storage in Concentrated Solar Power (CSP) plants. Moreover, it is composed of earth-abundant, inexpensive and non-toxic elements and exhibits a high-energy storage density, which are desirable characteristics for decreasing the deployment costs of the system. However, it undergoes decomposition at pO₂ ≤ 0.008 atm and temperature ≥ 1100 °C. Here the possibility of overcoming this limitation and extending the operating temperature range by B-site doping with Fe (CaFe_xMn_1–xO_3–δ0) is explored. Two doping levels are investigated, x = 0.1 and 0.3. The enthalpy of reduction was determined from a measurement of continuous equilibrium non-stoichiometry curves (δ, T) at several pO₂, enabling an evaluation of the heat storage capacity with high accuracy over widely ranging oxygen non-stoichiometry. Introduction of 0.1 Fe (CaFe_0.1Mn_0.9O_3–δ0) prevented CaMnO3 decomposition up to 1200 °C at pO₂ = 0.008 atm, thus widening the operating temperature range and the oxygen reduction extent. The increase in the accessible nonstoichiometry translates into an increase in the heat storage capacity (QM (kJ mol_ABO3^–1)) from ~272 kJ kg_ABO3^–1 in CaMnO₃ to ~344 kJ kg_ABO3^–1 inmore » CaFe_0.1Mn_0.9O_3–δ0. While even larger changes in oxygen content were accessible in CaFe_0.3Mn_0.7O_3–δ0, the oxidation state changes are accompanied by a lower enthalpy of reduction, resulting in a diminished heat storage capacity of ~221 kJ kg_ABO3^–1.« less

Authors:

Mastronardo, Emanuela  ^[1];

• Search DOE PAGES for author "Mastronardo, Emanuela"
• Search DOE PAGES for ORCID "0000-0002-6564-4494"

Qian, Xin  ^[2];

• Search DOE PAGES for author "Qian, Xin"
• Search DOE PAGES for ORCID "0000-0002-6537-616X"

Coronado, Juan M.  ^[3];

• Search DOE PAGES for author "Coronado, Juan M."
• Search DOE PAGES for ORCID "0000-0003-1919-8371"

Haile, Sossina M. ^[2]

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+ Show Author Affiliations

1. Institute of Catalysis and Petrochemistry, Spanish National Research Council (CSIC), Madrid, Spain, Materials Science and Engineering
2. Materials Science and Engineering, Northwestern University, 60208 Evanston, USA
3. Institute of Catalysis and Petrochemistry, Spanish National Research Council (CSIC), Madrid, Spain

Publication Date:

Tue May 05 00:00:00 EDT 2020

Research Org.:

Northwestern Univ., Evanston, IL (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1615405

Alternate Identifier(s):

OSTI ID: 1985158

Grant/Contract Number:  

EE0008089.0000; EE0008089

Resource Type:

Published Article

Journal Name:

Journal of Materials Chemistry. A

Additional Journal Information:

Journal Name: Journal of Materials Chemistry. A Journal Volume: 8 Journal Issue: 17; Journal ID: ISSN 2050-7488

Publisher:

Royal Society of Chemistry (RSC)

Country of Publication:

United Kingdom

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY