Nonfluorinated Membrane with a Decentralized Ion-Transport Network Enables Efficient and Sustainable Polysulfide Redox Flow Batteries

作者：Feiran Wang, Shuang Luo, Jiafeng Lei, Fei Ai, Ka Lok Leung, Jun Fan, Yi‐Chun Lu · 发表于：Science Advances · 年份：2025 · DOI：10.1126/sciadv.aea0032 · 被引用次数：15 · 研究领域：Advanced battery technologies research、Membrane-based Ion Separation Techniques、Membrane Separation Technologies

Aqueous redox flow batteries are one of the most promising electrochemical energy storage technologies for long-duration energy storage. Polysulfide-based redox flow batteries are particularly attractive owing to ultra-low-cost/earth-abundant active materials and full decoupling of power and energy. However, their practical application has been prevented by poor cycle life resulting from polysulfide-crossover and a heavy reliance on costly fluorinated membranes (Nafion117, USD $800 to $3,500 per square meter), along with the environmental concerns associated with the fluorine-processing industries. Common fluorinated membranes such as Nafion are not only expensive but also inadequate to prevent polysulfide-crossover due to oversized ion-transport channels resulting from aggregated microphase separation. Here, we develop non-fluorinated sulfonated polyethersulfone (SPES)-based membrane with decentralized ion-transport channels to create high-quantity, smaller ion-transport channels. The reduced channel size helps to mitigate polysulfide-crossover while the high-quantity channels help to maintain high ionic conductivity. The developed SPES membrane showed a 20 times higher ionic selectivity at a drastically reduced cost (USD $12 to $66 per square meter) compared to the commercial Nafion membrane. The low-cost SPES-based membrane enabled stable cycling of full polysulfide-ferrocyanide redox flow batteries with a high coulombic efficiency (>99.9%) and energy efficiency (averag...