A Long‐Cycle‐Life Lithium–CO₂ Battery with Carbon Neutrality

Lithium-CO₂ batteries are attractive energy-storage systems for fulfilling the demand of future large-scale applications such as electric vehicles due to their high specific energy density. However, a major challenge with Li-CO₂ batteries is to attain reversible formation and decomposition of the Li₂ CO₃ and carbon discharge products. A fully reversible Li-CO₂ battery is developed with overall carbon neutrality using MoS₂ nanoflakes as a cathode catalyst combined with an ionic liquid/dimethyl sulfoxide electrolyte. This combination of materials produces a multicomponent composite (Li₂ CO₃ /C) product. The battery shows a superior long cycle life of 500 for a fixed 500 mAh g⁻¹ capacity per cycle, far exceeding the best cycling stability reported in Li-CO₂ batteries. The long cycle life demonstrates that chemical transformations, making and breaking covalent CO bonds can be used in energy-storage systems. Theoretical calculations are used to deduce a mechanism for the reversible discharge/charge processes and explain how the carbon interface with Li₂ CO₃ provides the electronic conduction needed for the oxidation of Li₂ CO₃ and carbon to generate the CO₂ on charge. This achievement paves the way for the use of CO₂ in advanced energy-storage systems.