Cathode Local Curvature Affects Lithium Peroxide Growth in Li-O2 Batteries.

The growth of lithium peroxide (Li2O2) in cathodes determines the performance of lithium-oxygen batteries (LOBs). The factor affecting the Li2O2 growth position is of great importance. Here, three hollow carbon spheres with diameters of 200 nm, 500 nm, and 2 μm, corresponding to different curvatures of 10, 4, and 1, respectively, are prepared as LOB cathodes. It is found that the larger the curvature, the more difficult it is for Li2O2 to grow inside the hollow sphere. Increasing the discharge current density can promote the growth of Li2O2 onto a highly curved concave substrate. Therefore, to maximize the battery performance, the applied current density and the local curvature of the porous cathode need to match to optimize the pore space utilization and meanwhile to enhance the interface charge transfer between Li2O2 and electrode. The revealed relationship among the local curvature of the porous electrode, Li2O2 deposition position, and battery performance is valuable to the topography design of the LOB cathode.