Property evaluation of custom-made ion exchange membranes for electrochemical performance in reverse electrodialysis application

Abstract

Reverse electrodialysis (RED) is an emerging energy conversion process that utilizes the ion exchange membranes for salinity gradient power generation. As a primary component in RED, the development of suitable ion exchange membrane is crucial for sustainable energy harvest from various forms of salinity gradients. However, a great challenge still exists in designing and tailoring the RED membranes due to lack of understanding of the complexed relationships among properties of the membranes. This work presents the physical and electrochemical properties of a series of custom-made and commercial IEMs and investigates an interconnected relationship that affects the performance. Also, various membrane combinations comprised of custom-made and commercial membranes are tested in RED stack to evaluate the significance and dependency of the key membrane properties toward the power output via RED. The findings of this study suggest that the membranes having lower area resistance is much more influential regardless of its permselectivity level to perform better in RED. In this work, a combination of custom-made membranes with significantly low area resistance as well as low permselectivity obtained the highest power density. This observation implies that the ion conductance through the membrane should be the priority concern for the power generation in RED than ion selectivity of membrane. The result of this work provides the direction of effective membrane design with proper property orientation for RED application.