Constructing foldable and stretchable proton exchange membranes through spin coating technology

Abstract

The convenient storage of fuel cells requires the foldable and stretchable membrane electrolytes. However, there was the risk of sacrificing the charge transport mobility and mechanical strength to achieve the foldability and stretchability. The spin coating technology provided an facile strategy to prepare the well-ordered structure of membranes. In this study, the foldable and stretchable proton exchange membranes (PEMs) based on Kevlar nanofibers and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) were constructed through spin coating technology. After the folded and stretched operations, the membranes exhibited the negligible effect on proton conductivity and mechanical strength. In our opinion, the components of SEBS supported the membranes deformation and Kevlar naonfibers supplied the proton conduction channels. As a result, the prepared (Kevlar/SEBS)5 membranes can be folded in the width direction for 3 times and be stretched up to 10 % strain parallel to the length direction for 50 times. The folded membranes and stretched membranes respectively exhibited the proton conductivities of 9.55 × 10-2 S/cm and 1.98 × 10-1 S/cm, which were comparable with 1.58 × 10-1 S/cm at 160 °C of the original membranes. The tensile stress of (Kevlar/SEBS)5-fold/PA and (Kevlar/SEBS)5–50/PA respectively reached 5.23 MPa and 6.43 MPa, even a little higher than 3.59 MPa of the (Kevlar/SEBS)5/PA membranes. Furthermore, the folded and stretched membranes showed the fine component stability and proton conductivity stability. This study provided the support to exploit foldable and stretchable PEMs with spin coating technique, facilitating the easy storage of PEMs and future portable fuel cells.