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Batteries

Breakthrough in Vanadium Redox Flow Battery Technology

Strategic Insights

— 2 min read

Research conducted at Jilin University in China has resulted in a significant advancement in the development of advanced membranes for vanadium redox flow battery (VRFB) technology. The team, led by Yue Ao, has designed a novel class of ether-free poly(fluorenyl-co-imidazoliumisatin) (PFIMIS-x%) membranes that exhibit high ion conductivity and long-term stability. The membranes are prepared through a rational copolymerization process, followed by a phosphoric acid pre-swelling strategy. The resulting membrane demonstrates exceptional performance, with a low area resistance of 0.27 Ω cm, extremely low vanadium permeability (6.85 × 10^(-9) cm/min), and excellent ion selectivity of 2.97 × 10^(-3) S/min cm. The optimized PFIMIS-20%-5 M membrane achieves superior performance in VRFB single battery tests, including an energy efficiency of 72.7% at 300 mA/cm, a 196 h self-discharge duration, a peak power density of 521.2 mW/cm, and exceptional cycling stability over 600 cycles at 150 mA/cm.

Key Takeaways:

  • The developed PFIMIS-x% membranes exhibit high ion conductivity and long-term stability, addressing the critical challenge in VRFB technology.
  • The phosphoric acid pre-swelling strategy enhances the chain packing and microphase separation of the copolymer, leading to improved performance and a well-balanced structure-property relationship.
  • The optimized PFIMIS-20%-5 M membrane demonstrates exceptional performance, with a low area resistance of 0.27 Ω cm, extremely low vanadium permeability (6.85 × 10^(-9) cm/min), and excellent ion selectivity of 2.97 × 10^(-3) S/min cm.
  • The membrane exhibits excellent chemical stability over 400 hours and achieves superior performance in VRFB single battery tests.
  • The research offers new insights into molecular design strategy for developing high-performance membranes in advanced energy storage systems.
  • The breakthrough has been peer-reviewed and published in the Journal of Colloid and Interface Science.
  • The research was conducted by Yue Ao and his team at Jilin University, with additional authors including Tong Mu, Yang Pang, Binghui Liu, Longyu Li, and Chengji Zhao.

Statistics:

  • The optimized PFIMIS-20%-5 M membrane demonstrates a low area resistance of 0.27 Ω cm.
  • The membrane exhibits extremely low vanadium permeability of 6.85 × 10^(-9) cm/min.
  • The membrane has an excellent ion selectivity of 2.97 × 10^(-3) S/min cm, 16 times higher than that of Nafion 212.
  • The membrane achieves an energy efficiency of 72.7% at 300 mA/cm.
  • The membrane exhibits a self-discharge duration of 196 hours.
  • The membrane has a peak power density of 521.2 mW/cm.
  • The membrane demonstrates exceptional cycling stability over 600 cycles at 150 mA/cm.

Sources:

  • Ao, Y., et al. "A phosphoric acid pre-swelling strategy to construct poly(fluorenyl-co-imidazoliumisatin) membranes with high ion selectivity and stability for vanadium redox flow battery." Journal of Colloid and Interface Science, 2025, vol. 703, no. 159, p. 139258, doi: 10.1016/j.jcis.2023.139258.
  • NewsRx. "Findings in the Area of Science Reported from Jilin University [A phosphoric acid pre-swelling strategy to construct poly(fluorenyl-co-imidazoliumisatin) membranes with high ion selectivity and stability for vanadium redox flow battery]." Chemicals & Chemistry, 31 Oct. 2025, p. 986.

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