Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework

Simon F Winterstein; Alexei F Privalov; Christopher Greve; Renée Siegel; Björn Pötzschner; Michael Bettermann; Lea Adolph; Jana Timm; Roland Marschall; Ernst A Rössler; Eva M Herzig; Michael Vogel; Jürgen Senker

doi:10.1021/jacs.3c09257

Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework

J Am Chem Soc. 2023 Dec 20;145(50):27563-27575. doi: 10.1021/jacs.3c09257. Epub 2023 Dec 7.

Affiliations

¹ Inorganic Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
² Institute for Condensed Matter Physics, Technical University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany.
³ Dynamics and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
⁴ Physical Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.

Abstract

Sulfonated, cross-linked porous polymers are promising frameworks for aqueous high-performance electrolyte-host systems for electrochemical energy storage and conversion. The systems offer high proton conductivities, excellent chemical and mechanical stabilities, and straightforward water management. However, little is known about mass transport mechanisms in such nanostructured hosts. We report on the synthesis and postsynthetic sulfonation of an aromatic framework (SPAF-2) with a 3D-interconnected nanoporosity and varying sulfonation degrees. Water adsorption produces the system SPAF-2^H₂0. It features proton exchange capacities up to 6 mequiv g^-1 and exceptional proton conductivities of about 1 S cm^-1. Two contributions are essential for the highly efficient transport. First, the nanometer-sized pores link the charge transport to the diffusion of adsorbed water molecules, which is almost as fast as bulk water. Second, continuous exchange between interface-bound and mobile species enhances the conductivities at elevated temperatures. SPAF-2^H₂0 showcases how to tailor nanostructured electrolyte-host systems with liquid-like conductivities.