Effect of oxygen adsorbability on the control of Li2O2 growth in Li-O2 batteries: Implications for cathode catalyst design

Abstract

Understanding and controlling the growth of the vital Li2O2 product, which is associated with intrinsic property of cathode surface, is essential to design effective cathode catalysts in Li-O2 batteries. Herein we establish the correlation between the Li2O2 growth model and the O2 adsorbability on cathode surface that determines the pathway of the first electron transfer to O2. The weak O2 adsorbability drives the solution growth model to form Li2O2 toroid, while the strong one drives the surface growth model to thin film. Based on this mechanism, we select the N-doped carbon nanocages as cathode to realize a simultaneous large discharge capacity and low charge overpotential by forming copious thin-film Li2O2, deriving from its high specific surface area and enhanced O2 adsorbability due to N-doping. Our study demonstrates an effective strategy to design advanced cathode catalysts in Li–O2 batteries and potentially other metal-air batteries.