Mechanism of Charge/Discharge of Poly(vinylphenothiazine)-Based Li–Organic Batteries

Kolek M, Otteny F, Becking J, Winter M, Esser B, Bieker P

Abstract

Organic electrode materials are among the promising next generation compounds for battery energy storage as a greener and cheaper alternative to transition-metal-based electrodes. A prominent class among them are redox polymers, which can reversibly store energy and can be capable of fast redox processes. Nevertheless, drawbacks are their often low specific energy and lifetime. A main challenge is their solubility in battery electrolytes, which is detrimental to cell performance. Herein, we discuss the solubility properties of a polyvinyl-based redox polymer with a methylphenothiazine side group (PVMPT) in organic-solvent-based battery electrolytes and generate new insights into the mechanism of the redeposition process of dissolved active material. We addressed the mechanistic studies of this “polymer–electrolyte cross-talk” with microscopic and spectroscopic methods. These findings are important for the molecular design of new organic electrode materials, since the redeposited polymer showed improved cycling performance and outstanding cycling stabilities. We herein aim to draw a bigger picture of the solubility of redox polymers and its consequences and motivate the scientific community to reconsider the common conception of the deteriorating nature of the solubility of organic battery electrode materials.