Process for preparing doped lithium lanthanum zirconium oxide

A process for preparing a doped lithium lanthanum zirconium oxide (doped-LLZO) comprising the sequential steps of:

• (a) calcining a dry, powdered mixture of a co-precipitated lanthanum zirconium oxide (LZO) precursor, a dopant, and a lithium salt in an oxygen-containing atmosphere at a temperature in the range of about 500 to about 1100° C.;
• and
• (b) recovering the doped-LLZO;
• wherein the co-precipitated LZO precursor comprises a mixture of lanthanum oxide and/or lanthanum hydroxide in combination with zirconium oxide and/or zirconium hydroxide, in which the La and Zr are present in a La:Zr elemental ratio of about 3:2, and the La and Zr are uniformly mixed at the atomic level;
• the dopant is a salt or oxide of a dopant ion, X, wherein X is not a Li, La Zr, or O ion, X cations replace a portion of Li, La, and/or Zr in the formula Li7La3Zr2O12, and X anions replace a portion of O anion in the formula Li7La3Zr2O12;
• and the lithium salt and the dopant are mixed with the LZO precursor in amounts selected to achieve a target Li:La:Zr:X ratio in the doped-LLZO.