Pseudocapacitive Redox Polymers As Battery Materials: A Proof-Of-Concept All-Polymer Aqueous Battery

Redox polymers with distinct redox units have been long recognized for their pseudocapacitive and reversible charge storage behaviour. Many systems investigated so far have utilized organic electrolytes and/or have coupled a redox polymer half-cell to a non-polymer counter electrode. However, due to safety and sustainability considerations, aqueous electrolyte based charge storage in all-polymer configurations is considered a promising option for possible future applications. We present a strategy based on pseudocapacitive charge storage in Osmium-complex and viologen-modified redox polymers with specifically designed poly(vinylimidazole)- and poly(vinylpyridine)-based backbones. We couple both redox polymers in an aqueous battery configuration, demonstrating Nernst-potential driven energy storage. Electrochemical characterization in a concentric three-electrode Swagelok cell and coin cells reveals stable reversible capacities over more than 1800 cycles, with nearly quantitative coulombic efficiencies (>99.4 %) for the coin cells.