Fast ion conducting phosphate glasses and glass ceramic composites: Promising materials for solid state batteries

Fast ion conducting (FIC) phosphate glasses and glass ceramic composites have gained considerable importance due to their potential applications in the fabrication of solid-state batteries and other electrochemical devices. We, therefore, present an overview on various types of FIC glasses and glass ceramic composites. Silver phosphate glasses doped with different weight percent of lithium chloride (1, 5, 10 and 15 wt.%) were synthesized by melt quenching technique. The Ag2O–P2O5–(15 wt.%) LiCl glass exhibited the maximum electrical conductivity (σ = 8.91 × 10− 5 S cm− 1 at room temperature and 4.16 × 10− 3 S cm− 1 at 200 °C). Using this glass as an amorphous host material, glass–ceramic composites of Ag2O–P2O5–(15 wt.%) LiCl:xAl2O3 (x = 5–50 wt.%) were prepared. The ionic transference number, electrical conductivity, ionic mobility and carrier ion concentration of the synthesized samples were measured. Ag2O–P2O5–(15 wt.%) LiCl:(25 wt.%) Al2O3 composite system exhibited the maximum σ value (σ = 3.32 × 10− 4 S cm− 1 at room temperature and 2.88 × 10− 2 S cm− 1 at 200 °C ). Solid‐state batteries using undoped Ag2O–P2O5 glass, Ag2O–P2O5–(15 wt.%) LiCl glass and glass ceramic composite containing 25 wt.% Al2O3 as electrolytes were fabricated. The open circuit voltage (OCV) values and discharge time of these cells were measured and compared. It is found that the glass ceramic composites show enhanced ionic conduction, better OCV value and discharge characteristics.