High Ionic Flux Sub‐Micro Channels Membrane Model for Salinity Gradient Power Generation

Abstract Salinity gradient cells are widely used in power generation from gradient concentration solutions of one electrolyte. High ionic flux sub‐micro channels membrane can offer a high current density for salinity gradient power generation with a significant power output. Herein, based on numerical simulation model with Poisson‐Nernst‐Planck‐Navier‐Stokes (PNP‐NS) equations, a high ionic flux sub‐micro channel model with assumption is introduced that measured current is contributed by Cl⁻ ionic flux across the membrane. An ion channel system is built for experiment, in which a glass membrane with regular symmetric sub‐micro cylindrical channels and high effective channel area is applied, ion conductance and salinity gradient energy conversion property are tested. This PNP‐NS equations model simulation fits experiment well, its mechanism is also studied by the model. In addition, by mixing artificial sea water (0.5 m NaCl) and river water (0.01 mm NaCl), the output power density of this 50‐fold salinity gradient system can achieve 4.16 W m⁻², and the highest output power density will be up to 7.91 W m⁻² under a 0.5 m/0.001 m 500‐fold salinity gradient. This high ionic flux membrane shows a good performance for practical application in salinity gradient power generation.