Micropore-Confined Organic Solid for a High-Rate and Durable Electrode

The redox reactions of solid-state anthraquinone (AQ) confined within the micropores of activated carbon (AC) were investigated. A thin layer of AQ solid was adsorbed into the micropores of AC without inhibiting the formation of the electrical double layer. The AQ solid exhibited pseudocapacitive behavior and achieved 100% of its theoretical charge capacity (926 C g_-AQ^-1). Electrochemical impedance spectroscopy revealed that the capacitor response time of the AQ solid was shorter than those of the molecules dissolved in the electrolyte. This indicates that a direct charge transfer occurred from the carbon surface to the AQ solid. Regarding rechargeable aqueous air battery performance, the AQ solid demonstrated a discharge capacity of 257 mAh g_-AQ^-1 (99% of theoretical capacity) and a Coulombic efficiency of 99%. Both the cycling stability and rate performance of the AQ solid were superior compared with previously reported anode materials for rechargeable aqueous air batteries.