Long-Life Aqueous H⁺/K⁺ Dual-Cation Batteries Based on Dipyridophenazine//Hexacyanoferrate Electrodes

An aqueous rechargeable battery is considered as one of the most promising electrochemical energy storage devices due to its intrinsic safety and cost advantage. Herein, we report a long-life aqueous dual-cation battery operated in a mixed electrolyte containing potassium and hydrogen ions, where dipyridophenazine (DPPZ) and indium hexacyanoferrate (InHCF) are employed as the anode and cathode material, respectively. Owing to the reversible electrochemical amination of the DPPZ anode and fast intercalation/deintercalation of H+/K+ ions in the InHCF cathode, this dual-cation battery exhibits a large specific capacity of 134.4 mA h g–1 at 1 A g–1, excellent rate performance (retains 90 mA h g–1 up to 10 A g–1) and outstanding long-term cyclic stability (82.5% capacity retention, 99.7% coulombic efficiency, and 93.5% energy efficiency over 5000 cycles).