Iodine-doped sulfurized polyacrylonitrile with enhanced electrochemical performance for room-temperature sodium/potassium sulfur batteries. 
Iodine-doped sulfurized polyacrylonitrile (I-S@pPAN) is reported for room-temperature sodium sulfur (RT-Na/S) and potassium sulfur (RT-K/S) batteries operated in ester-based electrolytes.  It delivers an unprecedented capacity of 994 mA h g-1 at 2C (3350 mA g-1) for the RT-Na/S battery, whilst a reversible capacity of 947 mA h g-1 at 0.1C for the RT-K/S battery.