Superwetting Framework Polymer Membranes Enabling Fast TFSI^- Conduction for Nonaqueous Redox Flow Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Nonaqueous redox flow batteries (NARFBs) offer higher voltage than aqueous systems but face membrane challenges.
• Existing membranes suffer from conductivity-selectivity tradeoffs, poor wettability, and electrolyte incompatibility.

Purpose of the Study:

• To design and develop a novel microporous anion conductive membrane for NARFBs.
• To address swelling, wettability, and ion transport limitations in organic electrolytes.

Main Methods:

• Utilized a diversity-oriented design strategy for framework polymer membranes.
• Developed a microporous anion conductive membrane with enhanced acetonitrile affinity.
• Investigated ion diffusion coefficients and charge-carrier/electrolyte selectivity.

Main Results:

• The new membrane shows high resistance to swelling and superb wettability with acetonitrile.
• Achieved a TFSI- diffusion coefficient of 8.12 × 10-7 cm2 s-1 and selectivity of 433.
• Enabled NARFBs to operate at 80 mA cm-2 across temperatures with >99.5% Coulombic efficiency over 900 cycles.

Conclusions:

• The developed membrane significantly improves NARFB performance by enhancing ion transport and stability in organic electrolytes.
• This work provides a design strategy for membranes in organic electrochemical devices.
• Demonstrated potential for robust and efficient energy storage solutions.