Single‐Molecule Redox‐Targeting Reactions for a pH‐Neutral Aqueous Organic Redox Flow Battery

Abstract

Aqueous organic redox flow batteries (AORFBs) have received considerable attention for large‐scale energy storage. Quinone derivatives, such as 9,10‐anthraquinone‐2,7‐disulphonic acid (2,7‐AQDS), have been explored intensively owing to potentially low cost and swift reaction kinetics. However, the low solubility in pH‐neutral electrolytes restricts their application to corrosive acidic or caustic systems. Herein, the single molecule redox‐targeting reactions of 2,7‐AQDS anolyte are presented to circumvent its solubility limit in pH‐neutral electrolytes. Polyimide was employed as a low‐cost high‐capacity solid material to boost the capacity of 2,7‐AQDS electrolyte to 97 Ah L−1. Through in situ FTIR spectroscopy, a hydrogen‐bonding mediated reaction mechanism was disclosed. In conjunction with NaI as catholyte and nickel hexacyanoferrate as the catholyte capacity booster, a single‐molecule redox‐targeting reaction‐based full cell with energy density up to 39 Wh L−1 was demonstrated.

A Redox-Mediated Zinc–Air Fuel Cell

“…The concept of redox targeting (RT) of battery materials first proposed by Wang et al offers a feasible solution to address these issues by employing redox mediators (RMs) dissolved in the electrolyte. − To tackle the above challenges, here we present a redox-mediated Zn–air fuel cell (RM-ZAFC) based on the RT reactions of the complex cobalt triisopropanolamine (CoTiPA) and 7,8-dihydroxy-2-phenazinesulfonic acid (DHPS) with O 2 and Zn in the catholyte and anolyte, respectively. Due to the RT processes, the ORR and Zn oxidation reactions are both liberated from the electrode surface and occur inside separate reactor tanks (Figure ).…”