A proof‐of‐concept study was conducted on an all‐solid‐state rechargeable air battery (SSAB) using redox‐active 2,5‐dihydroxy‐1,4‐benzoquinone (DHBQ) and its polymer (PDBM) and a proton‐conductive polymer (Nafion). DHBQ functioned well in the redox reaction with the solid Nafion ionomer at 0.47 and 0.57 V vs. RHE, similar to that in acid aqueous solution. The resulting air battery exhibited an open circuit voltage of 0.80 V and a discharge capacity of 29.7 mAh gDHBQ−1 at a constant current density (1 mA cm−2). With PDBM, the discharge capacity was much higher, 176.1 mAh gPDBM−1, because of the improved utilization of the redox‐active moieties. In the rate characteristics of the SSAB‐PDBM, the coulombic efficiency was 84 % at 4 C, which decreased to 66 % at 101 C. In a charge/discharge cycle test, the capacity remaining after 30 cycles was 44 %, which was able to be significantly improved, to 78 %, by tuning the Nafion composition in the negative electrode.

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Rechargeable air batteries utilize oxygen from the atmosphere as the active material in the positive electrode and have high potential as next‐generation energy devices owing to their high energy density. In their Research Article (e202304366), Kenji Miyatake et al. design all‐solid‐state rechargeable air batteries, in which the negative electrode is free from metals and consists of a redox‐active molecular compound or its polymer to achieve high discharge capacity, rate characteristics, and cyclability.