Lithium-conducting solid electrolytes in the Li4SiO4-Li3VO4 system

The solubility of solid solutions in the Li4SiO4-Li3VO4 system is studied. The samples for the study have been prepared by means of preliminary interaction of Li4SiO4 and Li3Vu4 powders at 1000 deg C, and sulsequent pressing and sintering at 1050-1150 deg C. The electric resistance is measured in the temperature ranges from 750 to 350-300 deg C at 50 deg intervals. The X-ray diffraction and thermogravimetric analyses of the samples are made. The systems studied are stated to have three types of solid lithium-conducting electrolytes formed: 1) with the structure Li4SiO4 (Li3VO4 amount is up to 25-30 mol.%), 2) with the P structure, close to #betta#-Li3VO4 (Li3VO4 amount is from 30-35 to 75-85 mol.%), 3) with the structure #betta#-Li3VO4 (Li4SiO4 amount is up to 10-15 mol.%). The effect of Li3VO4 introduction on the electric properties of lithium orthosilicate consists in the formation of lithium vacancies as a result of anion [VO4]3- group substitution for [SiO4]4- group. Electrolytes with the P-structure have the highest conductivity in the given system and the lowest activation energy which in the low-temperature region is 40-42 kJ/mol for electrolytes containing 40-55 mol.% Li3VO4