Thermal stability of active electrode material in contact with solid electrolyte

For lithium battery systems including solid-state batteries, the solid electrolytes are playing an important role in enhancing the lithium transportation through the electrode/electrolyte interface resulting in the enhanced electrochemical performance of active materials which can prevent the dendrite formation for long term cycle life. However, the formation of the solid electrolyte film on the materials' surface is carrying on via various types of methods. Especially for oxide-salt-type of solid electrolytes of Li 2 O–M x O y –Li x X y system, these solid electrolyte is forming on the surface of materials via the melt quenching technique at above 500 °C that can lead to the unstable and degradation the structure of the active materials resulting in the lower performance compared to the traditional (wet-chemistry or solid stare reaction) formation of solid electrolyte film. In this work, the thermochemical stability of the active material in contact with the solid electrolyte after formation via a high-temperature method is investigated by the thermogravimetric and X-ray diffraction analysis, and galvanostatic charge–discharge and cyclic voltammetry measurements confirm that the electrochemical degradation can be attributed mainly to the partial destruction of cathode structure and surface oxidation of current collector leading to the lower electrochemical performance. The results suggest that the process formation of solid electrolyte film of the oxide-salt system should not exceed 250–300 °C and is highly relevant to a critical area for the active electrode materials without the degradation of the material structure and decreasing electrochemical performance. Graphic abstract