An Aqueous All‐Quinone‐Based Redox Flow Battery Employing Neutral Electrolyte

Abstract Redox flow batteries (RFBs) are considered as promising candidates for large‐scale energy storage. However, traditional RFBs based on toxic metal ions have deficiencies in resource utilization and environmental protection. Considering the corrosiveness of acidic and alkaline electrolytes and sustainability of energy storage devices, neutral aqueous organic redox flow batteries (AORFBs) have more development prospects. Herein, an AORFB is reported, using 9,10‐anthraquinone‐2,7‐disulfonic salt (2,7‐AQDS) and 1,4‐dihydroxyphenylsulfonate potassium (HQS) as negative and positive electroactive materials, respectively. It is found that the anions in the neutral solution further affected the solubility and kinetics of the electroactive materials by affecting the hydrogen bond in the solution, and the Na 2 SO 4 solution showed the optimal comprehensive performance. Therefore, an all‐quinone AORFB employing neutral Na 2 SO 4 electrolytes with a cell voltage of 0.9 V is constructed, which presented a capacity utilization of 70.1% and delivered stable cycling performance at 60 mA cm −2 . This work designs an innovative neutral all‐quinone AORFB and points out how anions affect the properties of the electrolyte by affecting hydrogen bonds within the solution. These findings open a new avenue for the design and application of neutral all‐organic aqueous RFBs.