context: Yao et al. presented a series of aqueous systems with quinone-based anodes and industrially established cathodes, which showed excellent stability, kinetics and energy density. Particularly for K-based batteries, PAQS P1 was paired with Ni(OH)2 in alkaline media (10 M KOH). The anode showed a capacity of 200 mA h g−1. At r.t., the full cell energy density (79 W h kg−1/138 W h L−1) was smaller than for a nickel metal hydride battery (180 W h kg−1/597 W h L−1), partially due to a relatively high anode potential. However, the capacity retention (88% after 1300 cycles) was better than for the best metal hydrides. Moreover, the capacity of PAQS decreased only by 7% as the temperature decreased from 25 to −25 °C. It is in contrast with Ni-MmH, whose energy density significantly decreases at lower temperatures.