A Super-Electron-Donor Polymer Enabling a Low-Voltage Anion-Insertion Battery

The design flexibility of organic materials has enabled numerous applications for energy storage systems. In the field of all-organic batteries, anionic rocking-chair batteries were introduced as promising metal-free alternative, yet few examples of low-potential p-type materials for the negative electrode are known. We herein present 2,2’ bipyridinium-based polymers with a two-electron redox process at an operating potential of 1.8 V vs. Li/Li+ as negative electrode-active material. Inspired by the class of super-electron-donors, we adapted the synthesis to obtain redox-active polymers with reduced solubility. We optimized the electrode composition, thereby increasing the active material mass loadings to up to 3.1 mg cm−2, and tested different electrolytes to assess the electrochemical properties of the material versus lithium. The 2,2’ bipyridinium-based polymers demonstrate how synthetic design strategies can guide the development of novel organic electrode materials. By further expanding the potential window in anionic rocking-chair batteries, this battery type can become an important post-lithium storage alternative.