Enhancing proton conductivity of phosphoric acid‐doped Kevlar nanofibers membranes by incorporating polyacrylamide and 1‐butyl‐3‐methylimidazolium chloride

Abstract

Freeze-drying (fd) technique is an effective and facile method to accumulate nanofibers for membrane preparation, and it has been frequently reported in the development of energy materials. Kevlar as amide nanofibers (ANFs) could serve as support materials for proton exchange membranes (PEMs) owing to the merits of exceptional stiffness and strength, etc. The aim of this research is to enhance the proton conductivity of phosphoric acid (PA)-doped Kevlar membranes by incorporating polyacrylamide (PAM) and 1-butyl-3-methylimidazolium chloride (bmimCl) with freeze-drying technique. The components of PAM and bmimCl could provide the binding sites to combine PA molecules with the formation of Kevlar/PAM/bmimCl/PA membranes. Furthermore, the prepared membranes with the freeze-drying posttreatment are substantially more effective at enhancing proton conductivity owing to the combination of more PA molecules. Specifically, Kevlar/PAM/bmimCl(fd)/PA membranes showed the anhydrous proton conductivity of 2.64 × 10−1 S/cm at 180°C and 1.04 × 10−1 S/cm at 140°C in a 270-hour non-stop test. As regard to the prepared PA-doped Kevlar/CdTe-based membranes, the mechanical strength was far from what was expected. Comparing to the solution casting method, the freeze-drying technique was a feasible strategy to deal with ANFs for exploiting high-temperature PEMs with high performance.