Rechargeable batteries with iodine-based cathodes have recently been the subject of significant interest due to the moderately high theoretical specific energy (≈600 Wh kg−1) and high-rate capability (>5 C) of the iodine cathode. Progress however has been impeded by the relatively low iodine contents of reported iodine-based cathodes. This is likely due to high rates of poly-iodide shuttling and cell instability that takes place at higher cell loadings. To reinforce the lithium metal anode, oxygen gas is introduced in the cells, which leads to a more robust solid-electrolyte interphase (SEI) layer, improving cell stability. This oxygen-assisted lithium-iodine (OALI) battery overcomes many of the shortcomings of other reported lithium-iodine batteries by utilizing a simple to fabricate lithium iodide (LiI) on activated carbon cathode with cell operating under an oxygen containing atmosphere to realize high-rate capability (>50 mA cm−2) and high areal capacity (>12 mAh cm−2).