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Updated: Jan 12, 2026

A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery
Published on: February 13, 2017
Nonfluorinated membrane with a decentralized ion-transport network enables efficient and sustainable polysulfide
Feiran Wang1, Shuang Luo2, Jiafeng Lei1
1Electrochemical Energy and Interfaces Laboratory, Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong SAR, China.
Abstract:
Polysulfide-based redox flow batteries are promising for long-duration energy storage, owing to ultralow-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 (Nafion 117, USD $800 to $3500 per square meter), along with the environmental concerns. Here, we develop a nonfluorinated sulfonated polyethersulfone (SPES)-based membrane with decentralized ion-transport channels, achieving a 20 times higher ionic selectivity at a markedly 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 polysulfide-ferrocyanide redox flow batteries with a high coulombic efficiency (>99.9%) and energy efficiency (average >75%) for 1600 cycles (>6 months). This strategy demonstrated polysulfide-based redox flow batteries with a record longevity using a low-cost and sustainable membrane, paving the way for their practical commercialization.
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