Aluminum-doped lithium ion conductor based on a garnet structure

1 . An aluminum-doped lithium ion conductor based on a garnet structure, comprising:

an aluminum-doped lithium lanthanum zirconate (LLZO) co-doped on a lanthanum site with Y 3+ and at least one other trivalent cation having an ionic radius that is smaller than that of La 3+ , with the exception of Al 3+ , wherein the conductor has a lithium content that is superstoichiometric in comparison to a stoichiometric garnet structure,

wherein the conductor has 90.1% or more of cubic crystal modification and 9.9% or less of tetragonal crystal modification,

wherein the conductor has a lattice constant of a <12.965 Å,

wherein the conductor has the chemical formula:

Li 7−3x+y′+2y″−z′−2z″+u Al x 3+ La 3−y−y′−y″ M y 3+ M y′ 2+ M y″ 1+ Zr 2−z−z′−z″ M z 4+ M z′ 5+ M z″ 6+ O 12±δ   (I)

in which:

M 3+ includes Y 3+ and the at least one other trivalent cation having an ionic radius smaller than La 3+ , with the exception of Al 3+ ,

M 2+ represents one or more divalent cations,

M 1+ represents one or more monovalent cations, with the exception of Lit,

M 4+ represents one or more tetravalent cations, with the exception of Zr 4+ ,

M 5+ represents one or more pentavalent cations,

M 6+ represents one or more hexavalent cations,

0.1≤x<1,

0<y<2,

0≤y′<0.2,

0≤y″<0.2,

0≤y′+y″<0.2,

0≤z<0.5,

0≤z′<0.8,

0≤z″<0.5,

0≤δ<2, and

wherein u>0.01 for a superstoichiometric lithium content.

2 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the following applies: 0.1≤x<0.5, with reference to one formula unit of the aluminum-doped lithium ion conductor based on a garnet structure in formula (I).

3 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the quantity of Y 3+ is <0.2 per formula unit of the aluminum-doped lithium ion conductor based on a garnet structure.

4 . The aluminum-doped lithium ion conductor according to claim 1 , further comprising:

a ratio for the content of cations per formula unit in chemical formula (I) given by (La+M 3+ +M 2+ +M 1+ )/(Zr+M 6+ +M 5+ +M 4+ +M 3+ ) greater than 1 and less than 1.5.

5 . The aluminum-doped lithium ion conductor according to claim 4 , wherein the content of each of M 6+ , M 5+ , M 4+ , M 2+ , and M 1+ is zero.

6 . The aluminum-doped lithium ion conductor according to claim 1 , further comprising:

a ratio for the content of cations per formula unit in chemical formula (I) given by (La+M 3+ +M 2+ +M 1+ )/(Zr+M 6+ +M 5+ +M 4+ +M 3+ ) in the decreasing range of 1.49 to 1.0.

7 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the at least one other trivalent cation is selected from the group consisting of: cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, bismuth, and indium.

8 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the at least one other trivalent cation is gadolinium and at least 0.1 mol of gadolinium is present per formula unit of the aluminum-doped lithium ion conductor based on a garnet structure.

9 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the at least one other trivalent cation is not polyvalent.

10 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the conductor has an amorphous phase, in which at least one selected from the group consisting of: lithium, aluminum, and M 3+ is enriched.

11 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the aluminum-doped lithium ion conductor has 95% or more of cubic crystal modification and 5% or less of tetragonal crystal modification.

12 . A powder composed of the aluminum-doped lithium ion conductor according to claim 1 , having a particle size in the range of d 50 =0.1 μm to 30 μm.

13 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the aluminum-doped lithium ion conductor is sintered and has an ion conductivity of more than 10 −5 S/cm.

14 . The aluminum-doped lithium ion conductor according to claim 1 , wherein the aluminum-doped lithium ion conductor has 98% or more of cubic crystal modification and 2% or less of tetragonal crystal.

15 . A method for producing an aluminum-doped lithium ion conductor, the method comprising:

melting initial materials in a skull crucible to form a melt; and

cooling the melt to form the conductor,

wherein the conductor is based on a garnet structure and comprises an aluminum-doped lithium lanthanum zirconate (LLZO) co-doped on a lanthanum site with Y 3+ and at least one other trivalent cation having an ionic radius that is smaller than that of La 3+ , with the exception of Al 3+ ,

wherein the conductor has a lithium content that is superstoichiometric in comparison to a stoichiometric garnet structure,

wherein the conductor has 90.1% or more of cubic crystal modification and 9.9% or less of tetragonal crystal modification,

wherein the conductor has a lattice constant of a <12.965 Å,

wherein the conductor has the chemical formula:

Li 7−3x+y′+2y″−z′−2z″+u Al x 3+ La 3−y−y′−y″ M y 3+ M y′ 2+ M y″ 1+ Zr 2−z−z′−z″ M z 4+ M z′ 5+ M z 6+ O 12±δ   (I)

in which:

M 3+ includes Y 3+ and the at least one other trivalent cation having an ionic radius smaller than La 3+ , with the exception of Al 3+ ,

M 2+ represents one or more divalent cations,

M 1+ represents one or more monovalent cations, with the exception of Li + ,

M 4+ represents one or more tetravalent cations, with the exception of Zr 4+ ,

M 5+ represents one or more pentavalent cations,

M 6+ represents one or more hexavalent cations,

0.1≤x<1,

0<y<2,

0≤y′<0.2,

0≤y″<0.2,

0≤y′+y″<0.2,

0≤z<0.5,

0≤z′<0.8,

0≤z″<0.5,

0≤δ<2, and

wherein u>0.01 for a superstoichiometric lithium content.