DIAPHRAGM FOR REDOX FLOW BATTERIES

A redox flow cell membrane includes a porous membrane (10) that has a mean flow pore size of not more than 100 nm, that has a thickness of not more than 500 µm, and that has an air flow rate of not less than 0.1 ml/s·cm 2 . When the redox flow cell membrane is used for a V-V-based redox flow cell, the porous membrane (10) preferably has a mean flow pore size of not more than 30 nm.