Progress of research on the conductive mechanism of the glassy electrolytes in lithium ion batteries

Glassy electrolytes have broad prospects for the application in all solid-state lithium ion batteries since they have isotropic conductivity and higher lithium ionic conductivity compared with ceramic electrolytes. In recent years, numerous groups have attempted to improve the lithium ionic conductivity, chemical and electrochemical stability of glassy electrolytes through nitrogen-incorporation by radio-frequency magnetron sputtering, preparing mixed former glasses and glass-ceramics by special technologies. In present review, conductive characteristics and mechanism in various glassy electrolytes are introduced. The micro-mechanisms of mixed former effect in several typical glassy electrolytes are discussed emphatically. The mixed former effect produces the non-bridge oxygen providing lithium-ion with the vacant place to move into or out, as well as expanding the lithium-ion conduction pathway to enhance ionic mobility in the network. The effect is brought about by the phase separation in micro structure of glassy electrolytes, which can be described as the isolation of continuous Li-rich phase with high ionic conductivity and isolated Li-poor phase with low ionic conductivity in micro structure. Finally, the premise conditions of mixed former effect occurring to a ternary glassy are summarized. Further study on conductive mechanisms of glassy electrolytes has important guiding significance for theory in developing glassy electrolytes with good chemical and electrochemical performances.