Cation‐Dependent Stabilization of Electrogenerated Naphthalene Diimide Dianions in Porous Polymer Thin Films and Their Application to Electrical Energy Storage. (10th September 2015)

• Record Type: Journal Article
• Authors: DeBlase, Catherine R.; Hernández‐Burgos, Kenneth; Rotter, Julian M.; Fortman, David J.; dos S. Abreu, Dieric; Timm, Ronaldo A.; Diógenes, Izaura C. N.; Kubota, Lauro T.; Abruña, Héctor D.; Dichtel, William R.
• Is Part Of: Angewandte Chemie. Volume 127:Number 45(2015)
• Page Start: 13423
• Page End: 13427
• Publication Date: 2015-09-10
• Subjects: Elektrische Energiespeichersysteme -- Elektrochemie -- Poröse Polymere -- Redoxprozesse -- Superkondensatoren; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201505289
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Porous polymer networks (PPNs) are attractive materials for capacitive energy storage because they offer high surface areas for increased double‐layer capacitance, open structures for rapid ion transport, and redox‐active moieties that enable faradaic (pseudocapacitive) energy storage. Here we demonstrate a new attractive feature of PPNs—the ability of their reduced forms (radical anions and dianions) to interact with small radii cations through synergistic interactions arising from densely packed redox‐active groups, only when prepared as thin films. When naphthalene diimides (NDIs) are incorporated into PPN films, the carbonyl groups of adjacent, electrochemically generated, NDI radical anions and dianions bind strongly to K +, Li +, and Mg 2+, shifting the formal potentials of NDI's second reduction by 120 and 460 mV for K + and Li + ‐based electrolytes, respectively. In the case of Mg 2+, NDI's two redox waves coalesce into a single two‐electron process with shifts of 240 and 710 mV, for the first and second reductions, respectively, increasing the energy density by over 20 % without changing the polymer backbone. In contrast, the formal reduction potentials of NDI derivatives in solution are identical for each electrolyte, and this effect has not been reported for NDI previously. This study illustrates the profound influence of the solid‐state structure of a polymer on its electrochemical response, which does not simply reflect the solution‐phase redox behavior of its monomers.