Rigid Framework-Constrained Membranes: A Key to Long-Life Polysulfide/Polyiodide Redox Flow Batteries

Area of Science:

• Energy Storage
• Materials Science
• Electrochemistry

Background:

• Polysulfide/polyiodide redox flow batteries (PSIBs) offer high capacity and low cost.
• Challenges include polysulfide/polyiodide crossover and limited cycle life due to membrane swelling.

Purpose of the Study:

• To develop a rigid framework-constrained membrane to mitigate ion crossover and improve cycle life in PSIBs.
• To investigate the structural optimization of composite membranes for enhanced battery performance.

Main Methods:

• Construction of a composite membrane using rigid carbonylated polymer of intrinsic microporosity (cPIM-1) and flexible perfluorosulfonic acid (PFSA).
• Utilized Quartz Crystal Microbalance and Positron Annihilation techniques to analyze membrane structure and channel size.
• Tested the performance of the composite membrane in a PSIB.

Main Results:

• The composite membrane (P/cPIM) successfully constrained the movement of PFSA polymer chains, optimizing membrane structure.
• PSIBs utilizing the P/cPIM membrane demonstrated stable operation for over 780 hours.
• This represents a significant improvement compared to the 165 hours achieved with the standard PFSA membrane.

Conclusions:

• The rigid framework-constrained composite membrane effectively suppresses ion crossover in PSIBs.
• The developed membrane technology enhances the cycle life and stability of PSIBs, paving the way for their practical application.