Abstract
The history of the all-solid-state battery, its revival with all its current craze, was previously introduced (end of 2018 lecture). Substantial progress has been made with inorganic ionic conductors. However, the complexity of interfaces means that our hopes must be tempered. This lecture therefore attempts to explain and describe the difficulties encountered in successfully mastering both Li-electrolyte and oxide-sulfide interfaces. It begins with a description of the methodology used to characterize the interfaces using symmetrical cells, and the development of in situ characterization techniques such as X-ray photoemission spectrometry to determine not only the nature, but also the kinetics of decomposition reactions at the interfaces. The mechanism of formation of the blocking layer at the positive electrode, at the oxide-sulfide interface, has also been explained and strategies to overcome it described. These strategies include the deposition of a buffer layer (mainly acid oxide) by sol-gel, atomic jet (ALD) or sputtering techniques.
