The power output of reverse electrodialysis (RED), an important renewable energy technology, can be improved using high-salinity feed solutions. Herein, a RED stack of ultrathin ion exchange membranes was operated continuously for 10 days using reverse osmosis brine (~0.9 M NaCl_equivalent) and underground water (~0.01 M NaCl_equivalent). The net power and net energy efficiency were initially 1.8 W m⁻²_{cell pair} and 40.8%, respectively, and then decreased gradually, as did the generated current and stack resistance. This deterioration was caused not by conventional membrane fouling but by trapped water inside the polymer matrix of the anion exchange membrane, especially near the cathode. The high salinity gradient and ultrathin membranes caused a flux imbalance between co-ion transport and osmotic water permeation. Further, bulk mass transfer was enhanced inside the RED stack to maintain electroneutrality. Therefore, combinations of membranes with high water permeability and permselectivity may be required to achieve stable RED operation.

反向电渗析 (RED) 是一种重要的可再生能源技术，可以使用高盐进料溶液来提高其功率输出。在此，使用反渗透盐水（约 0.9 M 氯化钠_当量）和地下水（约 0.01 M 氯化钠_当量）连续运行 RED 超薄离子交换膜堆栈 10 天。净功率和净能量效率最初分别为1.8 W m ^-2_电池对和40.8%，然后逐渐下降，产生的电流和堆电阻也是如此。这种恶化不是由传统的膜污染引起的，而是由阴离子交换膜的聚合物基质内的截留水引起的，尤其是在阴极附近。高盐度梯度和超薄膜导致共离子传输和渗透水渗透之间的通量不平衡。此外，RED 堆栈内部的整体传质得到增强，以保持电中性。因此，可能需要具有高透水性和渗透选择性的膜组合才能实现稳定的 RED 运行。