Ion/Molecule-selective transport nanochannels of membranes for redox flow batteries

Redox flow batteries (RFBs) are becoming an increasingly important means to power a green and renewable future. Advances in RFBs require an understanding of the construction of ion/molecule-selective transport nanochannels in high-performance and low-cost membranes for the application of large-scale energy storage. Enabling the control of ion/molecule transport at nanometer scales can achieve numerous functions, such as selectivity, conductivity, stability, and electrochemical performance, which result from diverse interactions between the ion/molecule and nanochannels. This paper presents an overview of the research and development of membranes with ion/molecule-selective transport nanochannels for RFB applications and particularly focuses on the basic principles, namely solvated ion/molecule sizes, functional groups, nanoscale confined dimensions, interactions, and environmental factors during ion/molecule-selective transport in nanochannels on the basis of their chemical and physical structures. Finally, we provide insights into the challenges and possible future research directions in the development of next-generation membranes for RFBs.