Space Charge Improved Poly(Aryl Ether Sulfone) Composite Membrane for Osmotic Energy Conversion

The ion-selective porous membrane is the key component in osmotic energy conversion, and optimizing its permeability and selectivity is crucial for improving output performance. Here, to construct a permeability and selectivity synergistically enhanced osmotic energy generator, the surface and space charge synergistically enhanced 3D composite membrane is prepared by inserting sulfonated hydrogels into the 3D ion channels with tunable surface charge. The membrane's selectivity is improved from 0.66 to 0.94 by increasing the charge density on the membrane surface and the spatial charge density of the membrane. The experimental and simulation results showed that the synergistic enhancement of the spatial and surface charges significantly improved the electrostatic interactions between the ions and the ion channels, which led to the enhancement of selectivity, net ionic fluxes, and output performance. The space charge improved composite membrane presents an advanced power density of about 6.4 W·m^–2 under a 50-fold concentration gradient, which is nearly 2 times that of the phase inversion membrane without hydrogels. Our study provides a promising solution for constructing high-performance osmotic energy generators.