Supramolecular complexation of nanoclusters with a non-fluorinated polymer for proton exchange membranes at intermediate temperatures

Abstract

Intermediate-temperature proton exchange membranes (PEMs) offer various benefits in fuel cells, including simplified water and thermal management, enhanced fuel tolerance, and improved electrochemical kinetics. In this study, a Keggin-type nanocluster is complexed with polyvinyl alcohol via a simple solution-casting method, and glycerol is used as a plasticizer to enhance the mobility of polymer molecular segments. Owing to the oxygen-rich surface configuration and anionic surface charge, the well-defined nanoclusters engage in diverse intermolecular interactions with polymers. Furthermore, glycerol establishes hydrogen bonds with the polymer, reducing the crystallinity of the polymeric matrix. The proposed proton conductor exhibits a robust intermediate-temperature proton conductivity of 2.03 × 10⁻³ S cm⁻¹ at 110 °C under anhydrous conditions. This work addresses the critical challenge of maintaining high proton conductivity under low-humidity conditions while ensuring thermal stability and mechanical integrity for PEMs at intermediate temperatures. Nevertheless, this simple solution-casting approach, based on the blending of Keggin-type nanoclusters and polymer via supramolecular interactions, is suitable for large-scale production.