Glass-ceramics based on Li1.5Al0.5Ge1.5(PO4)3 for advanced all-solid-state batteries

Glass-ceramic electrolytes of the Li1.5Al0.5Ge1.5(PO4)3-xB2O3 series (0≤x≤0.15 wt%) were obtained by glass crystallization under the same conditions of heat treatment. The influence of B2O3 addition on the phase composition and unit cell parameters of lithium-aluminium-germanium-phosphate glass-ceramics was investigated by XRD. The obtained solid electrolytes have the NASICON-type structure with space group R-3c. Glass-ceramics is single-phase at 0≤x≤0.15. Transport properties of glass-ceramics electrolytes were investigated by impedance spectroscopy. The conductivity of Li1.5Al0.5Ge1.5(PO4)3 was found to be lower compared to the B2O3-added solid electrolytes. Namely, the composition with 0.05 wt% has the highest lithium-ion conductivity, which is 5.5·10−4 S/cm at 25 °C. Also the thermal compatibility of Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte with Li4T5O12 anode material and the influence of Li3BO3 addition on their compatibility were investigated by DSC method.