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Mixed Metal‐Organic Frameworks as Efficient Semi‐Solid Electrolytes for Magnesium‐Ion Batteries

Hassan, Hagar K. 1; Farkas, Attila; Varzi, Alberto ORCID iD icon 1; Jacob, Timo 1
1 Helmholtz-Institut Ulm (HIU), Karlsruher Institut für Technologie (KIT)

Abstract:

One of the main issues of metal organic framework (MOF)-based solid electrolytes (SE) is their high guest solvent content reaching up to >50 wt% of the total mass of SE pellets. The presence of large solvent amounts reduces the SE hardness and the electrochemical stability in presence of a magnesium (Mg) anode. Moreover, this often leads to misleading ionic conductivity values. In the present work, a strategy to minimize the guest solvent in MOF-based SE from 44–55 wt% to 20–30 wt% of the total SE's mass is presented. Moreover, mixed metal organic frameworks of different structures and crystallinity are demonstrated for the first time to enhance the ionic conductivity of Mg$^{2+}$ ions inside the MOFs’ structures. The presence of both highly crystalline and amorphous MOFs increases the degree of disorder in the mixture and consequently opens up extra pathways for Mg$^{2+}$ ion diffusion. The ionic conductivity of mixed MOFs [amorphous Mgbp3dc and crystalline α-Mg$_3$(HCOO)$_6$] showed an enhanced value of 3.8×10$^{−5}$ S cm$^{−1}$ at 30 °C compared to 1.1×10$^{−6}$ S cm$^{−1}$ for α-Mg$_3$(HCOO)$_6$. Mixed MOF-SEs with a transference number (t+) of 0.335 showed a good stability in the presence of Mg electrodes with an enhanced reversibility upon galvanostatic cycling.


Verlagsausgabe §
DOI: 10.5445/IR/1000149818
Veröffentlicht am 15.08.2022
Originalveröffentlichung
DOI: 10.1002/batt.202200260
Scopus
Zitationen: 5
Web of Science
Zitationen: 5
Dimensions
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Helmholtz-Institut Ulm (HIU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 2566-6223
KITopen-ID: 1000149818
HGF-Programm 38.02.02 (POF IV, LK 01) Components and Cells
Erschienen in Batteries and Supercaps
Verlag John Wiley and Sons
Band 5
Heft 10
Seiten Art.Nr. e202200260
Vorab online veröffentlicht am 27.07.2022
Nachgewiesen in Web of Science
Dimensions
Scopus
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