Optimizing Membranes for Osmotic Power Generation

The design of ion-selective membranes is the key towards efficient reverse electrodialysis-based osmotic power conversion. The tradeoff between ion selectivity (output voltage) and ion permeability (output current) in existing porous membranes, however, limits the upgradation of power generation efficiency for practical applications. Thus, we provide the simple guidelines based on fundamentals of ion transport in nanofluidics for promoting osmotic power conversion. In addition, we discuss strategies for optimizing membrane performance through analysis of various material parameters in membrane design, such as pore size, surface charge, pore density, membrane thickness, ion pathway, pore order, and ionic diode effect. Lastly, a perspective on the future directions of membrane design to further maximize the efficiency of osmotic power conversion is outlined.