Solid Electrolyte Membranes Based on Li₂O-Al₂O₃-GeO₂-SiO₂-P₂O₅ Glasses for All-Solid State Batteries

Rechargeable Li-metal/Li-ion all-solid-state batteries due to their high safety levels and high energy densities are in great demand for different applications ranging from portable electronic devices to energy storage systems, especially for the production of electric vehicles. The Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) solid electrolyte remains highly attractive because of its high ionic conductivity at room temperature, and thermal stability and chemical compatibility with electrode materials. The possibility of LAGP production by the glass-ceramic method makes it possible to achieve higher total lithium-ion conductivity and a compact microstructure of the electrolyte membrane compared to the ceramic one. Therefore, the crystallization kinetics investigations of the initial glass are of great practical importance. The present study is devoted to the parent glasses for the production of Li_1.5+xAl_0.5Ge_1.5Si_xP_3-xO₁₂ glass-ceramics. The glass transition temperature T is determined by DSC and dilatometry. It is found that T decreases from 523.4 (x = 0) to 460 °C (x = 0.5). The thermal stability of glasses increases from 111.1 (x = 0) to 188.9 °C (x = 0.3). The crystallization activation energy of Si-doped glasses calculated by the Kissinger model is lower compared to that of Si-free glasses, so glass-ceramics can be produced at lower temperatures. The conductivity of the glasses increases with the growth of x content.