LAUSR

Carbon materials with high specific surface area are usually preferred to construct the air cathode of Li-air batteries due to their abundant sites for oxygen reduction and discharge product growth. However, the high surface area also amplifies electrolyte degradation during charge, which would become the threshold of cyclability after addressing the issue of electrode passivation and pore clogging, but is usually overlooked in relevant researches. In this work, we proved the critical influence of cathode surface area on the electrolyte consumption by adopting carbon-ceramic composites to reduce the surface area of air cathode. After screening several potential ceramic materials, an optimal composite of ketjenblack (KB) and La0.7Sr0.3MnO3 (LSM) delivered a discharge capacity even higher than that of the pure KB. This composite effectively mitigated the parasitic reaction current by 45% when polarized at 4.4 V vs. Li+/Li. Correspondingly, this composite prolonged the cell's cyclic life by 156%. Our results demonstrate that the electrolyte consumption during charge is one of critical boundary conditions to restrain the cyclic stability of Li-air batteries.