Delithiation dynamics of the LICGC electrolyte out of the voltage limits

The recently developed concept of an all-solid-state Li battery is deemed by many as a breakthrough toward safer and higher-capacity rechargeable devices. This, in turn, motivates the researchers in pushing all the battery components up to and beyond operational limits to test the materials’ performance. Herein we present an in-situ characterization of the response of the Lithium Conductive Glass-Ceramic (LICGC) solid electrolyte to the application of a cycling voltage, extending the operating limits up to ±15 V. The purpose was to clarify the dynamics of the delithiation process out of the standard conditions. The Atomic Force Microscopy (AFM) has been employed to monitor the evolution of the LICGC surface morphology induced by high voltage. The in-situ measurement showed that the delithiation of LICGC (encompassed with thin metallic current collectors) leads to the out-diffusion of Li through defects in the current collectors, and the formation of the Li-based nanoparticles (NPs) on the sample surface. The growth of NPs and the formation of nano-to-macro clusters is dependent on the applied voltage: the higher the voltage the larger the NPs. The AFM results are supported by the Neutron Depth Profiling data, which confirm high concentrations of Li in NPs, and by X-rays photoelectron spectroscopy, which clarifies the composition of NPs.