Rechargeable aqueous metal||I2 electrochemical energy storage systems are a cost-effective alternative to conventional transition-metal-based batteries for grid energy storage. However, the growth of unfavorable metallic deposition and the irreversible formation of electrochemically inactive by-products at the negative electrode during cycling hinder their development. To circumvent these drawbacks, herein we propose 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) as negative electrode active material and a saturated mixed KCl/I2 aqueous electrolyte solution. The use of these components allows for exploiting two sequential reversible electrochemical reactions in a single cell. Indeed, when they are tested in combination with an active carbon-enveloped I2 electrode in a glass cell configuration, we report an initial specific discharge capacity of 900 mAh g−1 (electrode mass of iodine only) and an average cell discharge voltage of 1.25 V at 40 A g−1 and 25$$\pm$$ ± 1 °C. Finally, we also report the assembly and testing of a PTCDI|KCl-I2|carbon paper multilayer pouch cell prototype with a discharge capacity retention of about 70% after 900 cycles at 80 mA and 25$$\pm$$ ± 1 °C.