Super-Electron-Donor Polymers: From Monomer Design to Redox Functionality

The design flexibility of organic materials has enabled numerous applications for energy storage systems. However, few examples of low-potential p-type materials for the negative electrode are known in the field of organic batteries, particularly relevant for anion-rocking-chair full-cells. Herein, we present a synthetic design to incorporate bridged 2,2'-bipyridinium units, which in their reduced form are known as super-electron-donors, into a polymer structure. By adapting their synthesis, we obtain a hydroxy-functionalized bridged bipyridinium salt with interesting structural features that are determined by molecular symmetry and environmental effects. Incorporation into a linear and cross-linked poly(methacrylate) reduces its electrolyte solubility, enabling its initial electrochemical evaluation in lithium battery half-cells. After testing electrodes with different compositions and screening electrolytes, we demonstrate that these polymers have the potential to function as electrode-active materials, operating at an attractively low potential of 1.8 V vs. Li/Li⁺. This work highlights the opportunities of low-potential 2,2'-bipyridinium-based polymers and demonstrates how synthetic design strategies can guide the development of novel organic electrode materials, providing a foundation for future research in this field.