The invention belongs to the technical field of battery materials, and particularly relates to a method for synthesizing a
lithium garnet type
solid electrolyte, which comprises the following steps: S1, heating and stirring a
metal ion solution, adjusting the pH value to 9-12, aging, filtering, and
drying filter residues to obtain precursor
powder; s2, mixing a
lithium source, a
lanthanum source, the precursor
powder and a doped
metal oxide, and carrying out ball milling,
drying and calcining to obtain core material
powder; s3, mixing a
lanthanum source, the precursor powder and a doped
metal oxide, and carrying out ball milling,
drying and calcining to obtain
coating layer intermediate powder; s4, taking the core material powder, the
coating layer intermediate powder and
lithium oxide, mixing, ball-milling, drying, sieving and tabletting to obtain a formed sheet; and S5, covering the formed sheet with the core material powder,
sintering, taking out the sheet, and
grinding and
polishing to obtain the lithium garnet type
solid electrolyte. The method provided by the invention can be used for preparing the
electrolyte with high
ionic conductivity, uniform
granularity and
high density.