Effects of thermal and rheological properties of deep eutectic solvents (DESs) on the Nafion proton conductivity for anhydrous fuel cells

This study intended to assess the effects of deep eutectic solvents (DESs) as electrolyte on the Nafion proton conductivity for anhydrous fuel cell applications. For this purpose, the effects of thermal and rheological properties of two types of DESs as their main characteristic features, on the Nafion proton conductivity, were examined. Thermal properties and viscosities of the synthesized DESs were evaluated using Differential Scanning Calorimetry (DSC) and Viscometery analysis, respectively. Moreover the effect of DES type and its properties on the through plane proton conductivity of Nafion membrane was evaluated. The obtained results revealed that the synthesized DESs are completely stable solutions with anti-ice feature. The electronegativity of hydrogen bond acceptor (HBA) used for DES synthesis is an important factor which can influence the glass transition temperature (Tg) of the DESs. Also, a HBA with a more electronegative halogen could provide a stronger hydrogen bond which results in a DES with higher viscosity. Interestingly anhydrous proton conductivity of Nafion was significantly influenced by halogen type in a way that the Bromide based Nafion/DES membranes have provided proton conductivity of ۳۳۷ mS/cm at ۱۰۰ ℃ at anhydrous condition which was about ۱۲۰% higher than that of the Iodide based Nafion/DES membranes.

Keywords:

Hydrogen , Nafion , PEM Fuel cell , Deep eutectic solvent