This technology enables the synthesis of LLZO (Li7La3Zr2O12) solid electrolytes for lithium secondary batteries by adding 7.5 mol% Al2O3 to control reactivity within alumina crucibles, thereby suppressing impurity formation and ensuring a stable cubic crystal structure.
In conventional LLZO synthesis, the reaction between the alumina crucible and LLZO powder generates impurities, which reduces ionic conductivity. To avoid this, expensive platinum crucibles have traditionally been required, creating significant cost barriers.
This technology involves a two-stage heat treatment process: an initial calcination of the raw material mixture (with 7.5 mol% Al2O3) at 800–850°C, followed by grinding and a second heat treatment at 1000–1050°C. The added Al occupies vacancies in the LLZO crystal lattice to stabilize the cubic structure, allowing for the synthesis of high-purity solid electrolytes using standard alumina crucibles. Applicable to the mass production of oxide-based all-solid-state battery electrolyte powders and lithium metal anode protective coatings, this method eliminates reliance on precious metal crucibles and significantly reduces capital expenditure for firing equipment.
This invention was developed with support from the Ministry of Education's Core Research Support Center program.
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