Improvement of Li1.5Al0.5Ge1.5(PO4)3 (LAGP) superionic conductivity via antimony doping

Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) solid electrolytes are promising for solid-state batteries (SSBs) because of their electrochemical and air stability. However, to improve the power characteristics of SSBs, increasing the ionic conductivity of the solid electrolyte is necessary. To improve the conductive properties of a superionic glass–ceramic electrolyte of the composition Li_1.5+xAl_0.5Sb_xGe_1.5-x(PO₄)₃, Sb was added. It employs the melt quenching technique, which includes a pre-synthesis stage that decreases the time and temperature of synthesis. An increase in the conductivity of the glass ceramic to 7.7⋅10⁻⁴ S⋅cm⁻¹ by antimony doping was discovered via impedance spectroscopy analysis. The introduction of antimony was discovered to improve the diffusion of lithium ions both in the bulk and at the grain boundaries. The influence of antimony on the grain boundary conductivity was explained by the change in the microstructure of the samples which consists of reducing the average crystallite size and improving contact between them. X-ray data were used to refine the structure parameters and atomic coordinates via the Rietveld method, which revealed a small increase in diffusion channels upon antimony introduction. Using a jump diffusion model, the thermodynamic assumptions for the increase in ionic conductivity were evaluated. The growth of the grain bulk conductivity is determined by increase in the pre-exponential factor.