Novel Conjugated Bipolar Molecules for Organic Redox Flow Batteries

Abstract

Developing a symmetrical redox flow battery that utilizes the same electroactive material for both the anode and cathode could significantly simplify the manufacturing process and reduce costs. However, the reported bipolar molecules exhibit low voltages(typically below 2V), and the challenge lies in finding suitable bipolar active molecules, which are barriers to the realization of bipolar redox flow batteries. Herein, we have developed a novel molecular strategy that involves the fusion of appropriate p-type and n-type redox materials to create bipolar molecules. Through which, electronic perturbations between the anodic and cathodic active sites lead to an effective voltage shift, enabling higher voltages in symmetrical batteries. We demonstrate the newly designed OBO molecules(where O and B are redox centers), which successfully exhibits bipolar redox activity and provides a high discharge voltage of approximately 3.05V in symmetrical batteries, one of the highest values reported to date. This simple conjugation approach offers a new perspective for the design of high-voltage, high-energy-density bipolar redox materials.