A Long-Cycle-Life Lithium-CO Battery with Carbon Neutrality.

Lithium-CO 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-CO batteries is to attain reversible formation and decomposition of the Li CO and carbon discharge products. A fully reversible Li-CO battery is developed with overall carbon neutrality using MoS nanoflakes as a cathode catalyst combined with an ionic liquid/dimethyl sulfoxide electrolyte. This combination of materials produces a multicomponent composite (Li CO /C) product. The battery shows a superior long cycle life of 500 for a fixed 500 mAh g capacity per cycle, far exceeding the best cycling stability reported in Li-CO 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 Li CO provides the electronic conduction needed for the oxidation of Li CO and carbon to generate the CO on charge. This achievement paves the way for the use of CO in advanced energy-storage systems.