Suitable acid groups and density in electrolytes to facilitate proton conduction. Issue 41 (13th October 2021)

• Record Type: Journal Article
• Authors: Ogawa, Takaya; Ohashi, Hidenori; Anilkumar, Gopinathan M.; Tamaki, Takanori; Yamaguchi, Takeo
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 41(2021)
• Page Start: 23778
• Page End: 23786
• Publication Date: 2021-10-13
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp00718a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Suitable acid groups and density are proposed to overcome the drawback of proton conducting materials that suffer from low proton conductivity under low-relative humidity conditions. Abstract : Proton conducting materials suffer from low proton conductivity under low-relative humidity (RH) conditions. Previously, it was reported that acid–acid interactions, where acids interact with each other at close distances, can facilitate proton conduction without water movement and are promising for overcoming this drawback [T. Ogawa, H. Ohashi, T. Tamaki and T. Yamaguchi, Chem. Phys. Lett., 2019, 731, 136627]. However, acid groups have not been compared to find a suitable acid group and density for the interaction, which is important to experimentally synthesize the material. Here, we performed ab initio calculations to identify acid groups and acid densities as a polymer design that effectively causes acid–acid interactions. The evaluation method employed parameters based on several different optimized coordination interactions of acids and water molecules. The results show that the order of the abilities of polymer electrolytes to readily induce acid–acid interactions is hydrocarbon-based phosphonated polymers > phosphonated aromatic hydrocarbon polymers > perfluorosulfonic acid polymers ≈ perfluorophosphonic acid polymers > sulfonated aromatic hydrocarbon polymers. The acid–acid interaction becomes stronger as the distance between acids decreases. The preferable distance between phosphonate moieties is within 13 Å.