TY - JOUR
T1 - Thermodynamic and Structural Effects of Fe Doping in Magnesium Manganese Oxides for Thermochemical Energy Storage
AU - Hashimoto, Jayni
AU - Bayon, Alicia
AU - Tamburro, Olivia
AU - Muhich, Christopher L.
N1 - Funding Information:
We gratefully acknowledge support from the U.S. Department of Energy Advanced Research Projects Agency─Energy under Award DE-AR0000991. We acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160. We acknowledge resources and support from the Metals, Environmental and Terrestrial Analytical Laboratory, part of the Chemical and Environmental Characterization Core Facilities at Arizona State University.
Publisher Copyright:
© 2023 American Chemical Society
PY - 2023/3/16
Y1 - 2023/3/16
N2 - Thermochemical energy storage potentially provides a cost-effective means of directly storing thermal energy that can be converted to electricity to satisfy demand, and MgxMn1-xO4 has been identified as a stable, high-energy density storage material. Here, we investigate the effects of doping small quantities of Fe into the MgMnOx system as a means to increase the reduction extent and storage energy via an increase in entropic contributions and the higher reduction energy of Fe as compared to that of Mn. We find that small additions of Fe (Mg0.5Mn0.4975Fe0.0025)3O4 (Fe = 0.5%) show increased reduction extent, but larger quantities of Fe (Mg0.5Mn0.485Fe0.015)3O4 and (Mg0.5Mn0.475Fe0.025)3O4 (Fe = 3 and 5%) show decreased reduction capability. This finding suggests that small quantities of Fe as a substituent change the thermodynamics of the material increasing the reduction extent through entropic effects, but at larger quantities of Fe, the higher reduction energy of Fe lowers the overall reduction capability. Additionally, the reduction occurs through the formation of intermediate phases which co-occur with the oxidized spinel and reduced halite phases; the presence of Fe significantly narrows the window where the intermediate phase is present, narrowing the T range where most of the reduction occurs.
AB - Thermochemical energy storage potentially provides a cost-effective means of directly storing thermal energy that can be converted to electricity to satisfy demand, and MgxMn1-xO4 has been identified as a stable, high-energy density storage material. Here, we investigate the effects of doping small quantities of Fe into the MgMnOx system as a means to increase the reduction extent and storage energy via an increase in entropic contributions and the higher reduction energy of Fe as compared to that of Mn. We find that small additions of Fe (Mg0.5Mn0.4975Fe0.0025)3O4 (Fe = 0.5%) show increased reduction extent, but larger quantities of Fe (Mg0.5Mn0.485Fe0.015)3O4 and (Mg0.5Mn0.475Fe0.025)3O4 (Fe = 3 and 5%) show decreased reduction capability. This finding suggests that small quantities of Fe as a substituent change the thermodynamics of the material increasing the reduction extent through entropic effects, but at larger quantities of Fe, the higher reduction energy of Fe lowers the overall reduction capability. Additionally, the reduction occurs through the formation of intermediate phases which co-occur with the oxidized spinel and reduced halite phases; the presence of Fe significantly narrows the window where the intermediate phase is present, narrowing the T range where most of the reduction occurs.
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U2 - 10.1021/acs.energyfuels.2c04266
DO - 10.1021/acs.energyfuels.2c04266
M3 - Article
AN - SCOPUS:85149391655
SN - 0887-0624
VL - 37
SP - 4692
EP - 4700
JO - Energy and Fuels
JF - Energy and Fuels
IS - 6
ER -