Unlocking Wide-Temperature Operation of High-Capacity Rechargeable Li/SOCl₂ Batteries with an Activated Carbon Host...

Lithium-thionyl chloride (Li/SOCl₂) batteries offer a high energy density (∼710 Wh kg^-1), high voltage plateau (∼3.5 V), and applicability in extreme temperature conditions (-55-150 °C), and their secondary system is considered a promising alternative for next-generation energy storage. However, the current rechargeable Li/SOCl₂ batteries exhibit unsatisfactory reversible capacities, especially under low-temperature conditions, where their reversibility drops sharply. This is primarily due to the poor oxidation efficiency of lithium chloride (LiCl) on the carbon surface. In this work, we engineered an activated carbon (AC) host featuring a high specific surface area and abundant oxygen-functional groups to enhance LiCl utilization. The AC particles provide numerous reaction sites through their microporous structure and modulate the interfacial kinetics via their oxygen-functional groups. This dual-functional role facilitates high LiCl oxidation while lowering electrochemical polarization. The Li/SOCl₂ batteries utilizing AC hosts (Li/SOCl₂@AC) deliver a high reversible capacity of 1500 mAh g^-1 with a discharge voltage plateau of ∼3.5 V. Moreover, the Li/SOCl₂@AC batteries can be durable for up to 200 cycles at a cycling capacity of 1000 mAh g^-1 even under -20 °C conditions. This work provides new insights into designing highly reversible rechargeable Li/SOCl₂ batteries with wide temperature adaptability.