Molecular Sieve Induced Solution Growth of Li₂O₂ in the Li-O₂ Battery with Largely Enhanced Discharge Capacity

The formation of the insulated film-like discharge products (Li₂O₂) on the surface of the carbon cathode gradually hinders the oxygen reduction reaction (ORR) process, which usually leads to the premature death of the Li-O₂ battery. In this work, by introducing the molecular sieve powder into the ether electrolyte, the Li-O₂ battery exhibits a largely improved discharge capacity (63 times) compared with the one in the absence of this inorganic oxide additive. Meanwhile, XRD and SEM results qualitatively demonstrate the generation of the toroid Li₂O₂ as the dominated discharge products, and the chemical titration quantifies a higher yield of the Li₂O₂ with the presence of the molecular sieve additive. The addition of the molecular sieve controls the amount of the free water in the electrolyte, which distinguishes the effect of the molecular sieve and the free water on the discharge process. Hence, a possible mechanism has been proposed that the adsorption of the molecular sieves toward the soluble lithium superoxides improves the disproportionation of the lithium superoxides and consequently enhances the solution-growth of the lithium peroxides in the low donor number ether electrolyte. In general, the application of the molecular sieve triggers further studies concerning the improvement of the discharge performance in the Li-O₂ battery by adding the inorganic additives.