Garnet materials for Li secondary batteries and methods of making and using garnet materials
Set forth herein are garnet material compositions, e.g., lithium-stuffed garnets and lithium-stuffed garnets doped with alumina, which are suitable for use as electrolytes and catholytes in solid state battery applications. Also set forth herein are lithium-stuffed garnet thin films having fine grains therein. Disclosed herein are novel and inventive methods of making and using lithium-stuffed garnets as catholytes, electrolytes and/or anolytes for all solid state lithium rechargeable batteries. Also disclosed herein are novel electrochemical devices which incorporate these garnet catholytes, electrolytes and/or anolytes. Also set forth herein are methods for preparing novel structures, including dense thin (<50 um) free standing membranes of an ionically conducting material for use as a catholyte, electrolyte, and, or, anolyte, in an electrochemical device, a battery component (positive or negative electrode materials), or a complete solid state electrochemical energy storage device. Also, the methods set forth herein disclose novel sintering techniques, e.g., for heating and/or field assisted (FAST) sintering, for solid state energy storage devices and the components thereof.
1. A method for sintering a thin and free standing garnet film, comprising the following steps:
providing a green tape thin film by casting a garnet slurry;
wherein the slurry comprises a lithium-stuffed garnet and a binder; and
wherein the slurry further comprises at least one member selected from the group consisting of a solvent, a plasticizer, a surfactant, a dispersant, and combinations thereof;
sintering the green tape thin film between setter plates;
wherein at least one of the setter plates is a ceramic setter plate comprising a material having a lithium concentration that is at least 10 atomic percent of the material;
wherein the sintering is heat, spark plasma, or field assisted sintering;
wherein sintering optionally includes applying pressure to the film with the setter plates; and
wherein one of the setter plates comprises ZrO 2 , SiO 2 , Al 2 O 3 , LiAlO 2 , LiLaO 2 , lithium-stuffed garnet, or Li 2 ZrO 3 .
2. The method of claim 1 , wherein the slurry comprises milled and calcined lithium-stuffed garnet.
3. The method of claim 1 , wherein the solid loading of the green tape is at least 30% v/v.
4. The method of claim 1 , wherein the solid loading of the green tape is at least 40% v/v.
5. The method of claim 1 , wherein the solid loading of the green tape is at least 50% v/v.
6. The method of claim 1 , wherein the solid loading of the green tape is at least 60% v/v.
7. The method of claim 1 , wherein the solid loading of the green tape is at least 65% v/v.
8. The method of claim 1 , wherein the film is sintered directly onto a metal.
9. The method of claim 8 , wherein the metal is a metal powder or a metal foil.
10. The method of claim 9 , wherein the metal is a metal powder between and in contact with one side of the green tape and one setter plate.
11. The method of claim 9 , wherein the metal is a metal powder layer positioned between and in contact with two green tapes, and wherein the green tapes are between and in contact with the setter plates.
12. The method of claim 8 , wherein the metal is Ni or Cu powder.
13. The method of claim 1 , wherein a source of Li in addition to the setter plates is placed in proximity of the sintered film during sintering.
14. The method of claim 1 , wherein one of the setter plates comprises lithium-stuffed garnet, and wherein the lithium-stuffed garnet is characterized by the empirical formula Li A La B M′ C M″ D Zr E O F , wherein 4<A<8.5, 1.5<B<4, 0≤C≤2, 0≤D≤2, 0≤E≤2, 10<F≤13, and M′ and M″ are, independently in each instance, either absent or are each independently selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta.
15. The method of claim 1 , wherein the pressure applied to the film with the setter plates is between 1 and 1000 PSI.
16. The method of claim 1 , wherein the solvent is selected from ethanol, isopropanol, toluene, ethyl acetate, methyl acetate, acetone, acetonitrile, or combinations thereof.