Rechargeable Aluminum/Iodine Battery Redox Chemistry in Ionic Liquid Electrolyte

Rechargeable aluminum ion batteries (RABs) have attracted much attention because of their high charge density, low cost, and low flammability. However, the traditional cathodes used in RABs had limited intercalation ability of Al3+ ion, leading to a low capacity. We report for the first time a rechargeable aluminum/iodine (Al/I2) battery. The unique conversion reaction mechanism of the Al/I2 battery chemistry avoids the cathode material disintegration during repeated charge–discharge processes, and this system successfully suppresses the shuttle of dissolved polyiodide in ionic liquid because of the hydrogen-bonding interaction, resulting in a robust rechargeable RAB system. The rechargeable Al/I2 battery based on the I3–/I– redox chemistry is demonstrated to be highly reversible in Al3+ ion storage, providing a high capacity of >200 mAh g–1 at 0.2C and high stability for even over 150 cycles at 1C. This work provides a new insight into designing a RAB system based on redox chemistry.