In Situ Realization of Water-Mediated Interfacial Processes at Nanoscale in Aprotic Li–O_2 Batteries

摘要

A fundamental understanding of the remarkable impact of water on the interfacial processes of lithium-oxygen (Li-O-2) reactions is of great significance for the practical application of Li-O-2 batteries. However, clarifying the growth pathway and surface dynamics of active products regulated by water at the nanoscale is still at a preliminary stage. Here, the interfacial evolution of cathode processes mediated by water in Li-O-2 batteries is successfully revealed by using in situ atomic force microscopy. Under the regulation of additive water, the morphology of discharge product Li2O2 is changed from a toroidal shape to a lamellar one with water content increasing, by contrast, the latter one shows a lower decomposition potential with faster dynamics upon charging. Moreover, real-time visualization directly shows that inducing water into the DMSO-based electrolyte can switch the pathway of Li2O2 nucleation from a surface-mediated mechanism to solution-mediated mechanism, which in turn affects product distribution and battery performance. Furthermore, it is found that the applied current density and additive water can antagonistically impact the interfacial behavior. The insights into the effect of water on the nucleation modes and evolution processes of Li2O2 provides a deeper understanding of the interfacial reactions in Li-O-2 batteries.