Redox-Active Water-Soluble Low-Weight and Polymer-Based Anolytes Containing Tetrazine Groups: Synthesis and...

Area of Science:

• Electrochemistry
• Polymer Science
• Materials Science

Background:

• Aqueous redox flow batteries (RFBs) are emerging as a sustainable energy storage solution.
• There is a growing need for novel, cost-effective, and environmentally benign redox-active organic compounds for RFB applications, particularly for anolytes.
• S-tetrazines are attractive due to their small size and reversible two-electron reduction in protic media.

Purpose of the Study:

• To synthesize and evaluate novel water-soluble redox-active s-tetrazine derivatives for use in polymer-based aqueous RFBs.
• To functionalize linear polymers and microgels with tetrazine groups for anolyte applications.
• To investigate the electrochemical properties and potential for tuning reduction potentials.

Main Methods:

• Synthesis of low molecular weight and polymeric s-tetrazine derivatives.
• Modification of linear polyacrylic acid and poly(N-isopropylacrylamide-co-acrylic acid) microgels with pendent 1,2,4,5-tetrazine groups.
• Electrochemical testing in aqueous acetate buffer solutions, including cyclic voltammetry and potentially other techniques to assess reversibility and kinetics.

Main Results:

• Successful synthesis of water-soluble tetrazine monomers and polymers (linear and microgel).
• Demonstrated chemical reversibility of the reduction process for tetrazine-containing polymers in aqueous solution.
• Identified that reduction potential can be tuned by modifying tetrazine core substituents.
• Observed improved reaction kinetics with carbon electrodes.

Conclusions:

• Novel water-soluble tetrazine-based polymers are viable candidates for anolyte materials in aqueous organic RFBs.
• The developed materials expand the range of available anodic materials for sustainable energy storage.
• Further optimization of tetrazine structure and electrode materials can enhance RFB performance.