Aryl Viologen Polymers in High‐Voltage Full‐Organic Batteries

Anion‐rocking chair batteries, functioning without any metals, are intriguing candidates as alternative, more sustainable energy storage systems. They can be operated by using two types of p‐type organic electrode‐active materials (OAMs) with low and high redox potentials for the negative and positive electrode, respectively. However, identifying compatible material pairs delivering a potential difference above 1.5 V is challenging. Viologens are promising candidates as low‐potential OAMs, but they usually lack stability when cycled over both redox processes. Herein, we report on linear and crosslinked N ‐aryl viologen polymers with enhanced electrochemical stability over both redox processes in lithium half‐cells. We employ these as negative electrodes in anion‐rocking chair full‐cells with a dimethoxyphenothiazine‐polymer‐based positive electrode, able to undergo two reversible oxidations. The full‐cell, using 2 m LiClO 4 in PC as electrolyte, delivered a voltage of ca. 1.8 V and a capacity of up to 78 mAh g −1 and could be cycled over 100 cycles with a capacity retention of 71%. We further demonstrate a metal‐free all‐organic full‐cell using n Bu 4 NClO 4 as electrolyte salt that delivers an even higher specific discharge capacity of up to 88 mAh g −1 . This work constitutes a step forward toward anion‐rocking chair batteries with attractive cell voltages exceeding 1.5 V.