There is an increasing need to develop an alternative to Nafion membrane in order to reduce the cost of vanadium redox flow batteries. Pore-filled composite membranes based on Nafion is one way to reduce the amount of costly material, however its chronic problem is low conductivity and water uptake ability. We suggest a novel approach to enhance the conductivity and water uptake by incorporating propylene carbonate to modulate water channel morphologies in Nafion directly. We present a pore-filled type Nafion composite membrane to prove the effect of PC addition. Small-angle X-ray scattering and simulation results are suggested for further understanding. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.