An all-organic aqueous potassium dual-ion battery

Benefiting from the environmental friendliness of organic electrodes and the high security of aqueous electrolyte, an all-organic aqueous potassium dual-ion full battery (APDIB) was assembled with 21 M potassium bis(fluoroslufonyl)imide (KFSI) water-in-salt as the electrolyte. The APDIB could deliver a reversible capacity of around 50 mAh g−1 at 200 mA g−1 (based on the weight of total active materials), a long cycle stability over 900 cycles at 500 mA g−1 and a high coulombic efficiency of 98.5%. The reaction mechanism of APDIB during the charge/discharge processes is verified: the FSI− could associate/disassociate with the nitrogen atom in the polytriphenylamine (PTPAn) cathode, while the K+ could react with CO bonds in the 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) anode reversibly. Our work contributes toward the understanding the nature of water-into-salt electrolyte and successfully constructed all-organic APDIB.