Annealed garnet electrolyte separators

• US 9,966,630 B2
• Filed: 01/27/2016
• Issued: 05/08/2018
• Est. Priority Date: 01/27/2016
• Status: Active Grant

• Current Assignee: Quantumscape Battery Incorporated
• Original Assignee: Quantumscape Corporation
• Inventors: Cheng, Lei, Iyer, Sriram, Gardner, Will, Holme, Tim, Li, Shuang, Chao, Cheng-chieh, Donnelly, Niall, Allenic, Arnold
• Primary Examiner(s): Fraser, Stewart A
• Application Number:
  US15/007,908
• Publication Number:
  US 20170214084A1
• Time in Patent Office: 832 Days
• CPC Class Codes: C04B 2235/3203 Lithium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3227 Lanthanum oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/6025 Tape casting, e.g. with a doctor blade
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/764 Garnet structure A3B2(CO4)3
• CPC Class Codes: C04B 35/4885 with aluminium oxide
• CPC Class Codes: C04B 35/62218 obtaining ceramic films, e.g. by using temporary supports
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/056 characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
• CPC Class Codes: H01M 10/0562 Solid materials
• CPC Class Codes: H01M 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 10/058 Construction or manufacture
• CPC Class Codes: H01M 50/403 Manufacturing processes of separators, membranes or diaphragms
• CPC Class Codes: H01M 50/409 Separators, membranes or diaphragms characterised by the material
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Set forth herein are pellets, thin films, and monoliths of lithium-stuffed garnet electrolytes having engineered surfaces. These engineered surfaces have a list of advantageous properties including, but not limited to, low surface area resistance, high Li⁺ ion conductivity, low tendency for lithium dendrites to form within or thereupon when the electrolytes are used in an electrochemical cell. Other advantages include voltage stability and long cycle life when used in electrochemical cells as a separator or a membrane between the positive and negative electrodes. Also set forth herein are methods of making these electrolytes including, but not limited to, methods of annealing these electrolytes under controlled atmosphere conditions. Set forth herein, additionally, are methods of using these electrolytes in electrochemical cells and devices. The instant disclosure further includes electrochemical cells which incorporate the lithium-stuffed garnet electrolytes set forth herein.

Claims

1. An electrolyte separator,

having top and bottom surfaces and a bulk therebetween, wherein the bulk has a thickness,

wherein the top or bottom surface length or width is greater than the thickness of the bulk by a factor of ten (10) or more, and the

thickness of the bulk is from about 10 nm to about 100 μ

m;

wherein the bulk is characterized by the chemical formula Li_xLa₃Zr₂O_zy(Al₂O₃), wherein 5≤

x≤

7.5, 11≤

z≤

12.25, and 0≤

y≤

1;

wherein both the top and bottom surfaces are characterized as having substantially no layer thereupon comprising a lithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, a hydrate thereof, an oxide thereof, or a combination thereof.

2. The electrolyte separator of claim 1, wherein the top or bottom surface length or width is from about 100 μ

m to 100 cm.

3. The electrolyte separator of claim 1, wherein x is 5, 5.5, 6, 6.5, 7, or 7.5.

4. The electrolyte separator of claim 1, wherein the electrolyte bulk is characterized by the chemical formula Li₅La₃Zr₂O_h0.2(Al₂O₃), Li₅La₃Zr₂O_h0.25(Al₂O₃), Li₅La₃Zr₂O_h0.3(Al₂O₃), Li₅La₃Zr₂O_h0.35(Al₂O₃), Li₅La₃Zr₂O_h0.4(Al₂O₃), Li₅La₃Zr₂O_h0.45(Al₂O₃), Li₅La₃Zr₂O_h0.5(Al₂O₃), Li₅La₃Zr₂O_h0.55(Al₂O₃), Li₅La₃Zr₂O_h0.6(Al₂O₃), Li₅La₃Zr₂O_h0.7(Al₂O₃), Li₅La₃Zr₂O_h0.75(Al₂O₃), Li₅La₃Zr₂O_h0.8(Al₂O₃), Li₅La₃Zr₂O_h0.85(Al₂O₃), Li₅La₃Zr₂O_h0.9(Al₂O₃), Li₅La₃Zr₂O_h0.95(Al₂O₃), Li₅La₃Zr₂O_h(Al₂O₃), Li₆La₃Zr₂O_h0.2(Al₂O₃), Li₆La₃Zr₂O_h0.25(Al₂O₃), Li₆La₃Zr₂O_h0.3(Al₂O₃), Li₆La₃Zr₂O_h0.35(Al₂O₃), Li₆La₃Zr₂O_h0.4(Al₂O₃), Li₃La₃Zr₂O_h0.45(Al₂O₃), Li₆La₃Zr₂O_h0.5(Al₂O₃), Li₆La₃Zr₂O_h0.55(Al₂O₃), Li₆La₃Zr₂O_h0.6(Al₂O₃), Li₆La₃Zr₂O_h0.65(Al₂O₃), Li₆La₃Zr₂O_h0.7(Al₂O₃), Li₆La₃Zr₂O_h0.75(Al₂O₃), Li₆La₃Zr₂O_h0.8(Al₂O₃), Li₆La₃Zr₂O_h0.85(Al₂O₃), Li₆La₃Zr₂O_h0.9(Al₂O₃), Li₆La₃Zr₂O_h0.95(Al₂O₃), Li₆La₃Zr₂O_h(Al₂O₃), Li₇La₃Zr₂O_h0.2(Al₂O₃), Li₇La₃Zr₂O_h0.25(Al₂O₃), Li₇La₃Zr₂O_h0.3(Al₂O₃), Li₇La₃Zr₂O_h0.35(Al₂O₃), Li₇La₃Zr₂O_h0.4(Al₂O₃), Li₇La₃Zr₂O_h0.45(Al₂O₃), Li₇La₃Zr₂O_h0.5(Al₂O₃), Li₇La₃Zr₂O_h0.55(Al₂O₃), Li₇La₃Zr₂O_h0.6(Al₂O₃), Li₇La₃Zr₂O_h0.65(Al₂O₃), Li₇La₃Zr₂O_h0.7(Al₂O₃), Li₇La₃Zr₂O_h0.75(Al₂O₃), Li₇La₃Zr₂O_h0.8(Al₂O₃), Li₇La₃Zr₂O_h0.85(Al₂O₃), Li₇La₃Zr₂O_h0.9(Al₂O₃), Li₇La₃Zr₂O_h0.95(Al₂O₃), Li₇La₃Zr₂O_h(Al₂O₃), Li₇La₃Zr₂O_h0.3(Al₂O₃), Li₇La₃Zr₂O_h0.35(Al₂O₃), Li₇La₃Zr₂O_h0.4(Al₂O₃), Li₇La₃Zr₂O_h0.45(Al₂O₃), Li₇La₃Zr₂O_h0.5(Al₂O₃), Li₇La₃Zr₂O_h0.55(Al₂O₃), Li₇La₃Zr₂O_h0.6(Al₂O₃), Li₇La₃Zr₂O_h0.65(Al₂O₃), Li₇La₃Zr₂O_h0.7(Al₂O₃), Li₇La₃Zr₂O_h0.75(Al₂O₃), Li₇La₃Zr₂O_h0.8(Al₂O₃), Li₇La₃Zr₂O_h0.85(Al₂O₃), Li₇La₃Zr₂O_h0.9(Al₂O₃), Li₇La₃Zr₂O_h0.95(Al₂O₃), or Li₇La₃Zr₂O_h(Al₂O₃);

wherein subscript h is a rational number from 11 to 12.25 and is selected to maintain charge neutrality.

5. The electrolyte separator of claim 4, wherein subscript h is 12.

6. The electrolyte separator of claim 1, wherein the bulk of the electrolyte separator is characterized by a chemical formula different from the top or bottom surface of the electrolyte separator.

7. The electrolyte separator of claim 1, wherein the bulk of the electrolyte separator is characterized by the chemical formula Li_x1La₃Zr₂O₁₂y(Al₂O₃), wherein 5≤

x1≤

7.5 and 0≤

y≤

1;

wherein the top or bottom surface or both is/are characterized by the chemical formula Li_x2La₃Zr₂O₁₂y(Al₂O₃), wherein 5≤

x1≤

7.5 and 0≤

y≤

1;

wherein x2 is less than x1.

8. The electrolyte separator of claim 1, wherein both the top and bottom surfaces are characterized as having no detectable presence of lithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, or a combination thereof as detected by XPS or FT-IR.

9. The electrolyte separator of claim 1, wherein both the top and bottom surfaces are characterized as having no secondary phases present on the top or bottom surface, wherein secondary phases are selected from LiAlO₂, Li₂ZrO₃, LaAlO₃, Li₅AlO₄, Li₆Zr₂O₇, La₂(Li_xAl₁₋

x), wherein x is from 0 to 1, or combinations thereof.

10. The electrolyte separator of claim 1, having a Li-metal interface area specific resistance between 0 and 15 Ω

cm² at 60°

C.

11. The electrolyte separator of claim 10, having a Li-metal interface area specific resistance is less than 2 Ω

cm² at 60°

C.

12. The electrolyte separator of claim 1, having a Li-metal interface area specific resistance less than 2 Ω

cm² at 25°

C.

13. The electrolyte separator of claim 1, having a Li-metal interface area specific resistance less than 20 Ω

cm² at −

25°

C.

14. The electrolyte separator of claim 1, wherein the separator is a pellet, a film, free-standing film, or a monolith.

15. The electrolyte separator of claim 1, wherein the lithium carbonate is characterized by Li_x(CO₃)_y and x is from 0 to 2, and y is from 0 to 1.

16. The electrolyte separator of claim 1, wherein the lithium hydroxide is characterized by Li_x(OH)_y and x and y are each, independently, from 0 to 1.

17. The electrolyte separator of claim 1, wherein the lithium oxide is characterized by Li_xO_y and x and y are each, independently, from 0 to 2.

18. The electrolyte separator of claim 1, wherein the electrolyte separator is characterized by an EPR spectrum having a spin density of approximately in the order of 1×

10<sup>−

18</sup>/cm₃ to 1×

10<sup>−

20</sup>/cm³.

19. The electrolyte separator of claim 1, wherein the top or bottom surface is characterized by an FT-IR spectrum substantially absent of peaks corresponding to Li₂CO₃.

20. The electrolyte separator of claim 1, wherein the top or bottom surface is characterized by a Raman spectrum having stretches characteristic of the garnet crystal structure and associated with ZrO₆, LaO₈ and LiO₄ chemical units and additional peaks at 515 cm⁻

1, 531 cm<sup>−

1</sup> and 711 cm<sup>−

1</sup>.

21. The electrolyte separator of claim 1, wherein the top or bottom surface is in direct contact with Li-metal.

22. The electrolyte separator of claim 1, having a top or bottom surface that has a carbon concentration at the surface of less than 5 atomic %.

23. The electrolyte separator of claim 1, having a top or bottom surface that has a hydrogen concentration at the surface of less than 5 atomic %.

24. The electrolyte separator of claim 22, wherein the atomic % of carbon is measured by XPS.

25. The electrolyte separator of claim 23, wherein the atomic % of hydrogen is measured by SIMS.

26. The electrolyte separator of claim 1, having an Oxygen (O) vacancy concentration characterized by an EPR signal spin density of 1×

10<sup>−

18</sup>/cm³ to 1×

10<sup>−

20</sup>/cm³.

27. The electrolyte separator of claim 26, having a spin density equal to about 1×

10<sup>−

19</sup>/cm³.

28. An electrochemical cell comprising a positive electrode, a negative electrode, and an electrolyte between the positive and negative electrode, wherein the electrolyte comprises the electrolyte separator of claim 1.

29. A method of cycling lithium through a solid state lithium ion conducting ceramic, comprising

providing an electrolyte separator according to claim 1 in contact with a lithium metal anode;

applying a pressure of at least 300 pounds per square inch (PSI) to the electrolyte separator and anode; and

cycling at least 10 μ

m of lithium metal at a current of at least 1 mA/cm² or greater.

30. A method of cycling lithium through a solid state lithium ion conducting ceramic, comprising

providing an electrolyte separator according to claim 1 in contact with a lithium metal anode;

applying a pressure of at least 20 PSI to the electrolyte separator and anode; and

cycling at least 20 μ

m of lithium metal at a current of at least 2 mA/cm² or greater.

31. An electrochemical cell comprising the electrolyte separator of claim 1, wherein the electrochemical cell further includes a gel electrolyte.

32. An electrochemical cell comprising the electrolyte separator of claim 1, wherein the electrochemical cell further includes a gel electrolyte between the positive electrode active material and the electrolyte separator.

33. The electrochemical cell of any one of claims 31-32 wherein the gel comprises a solvent, a lithium salt, and a polymer.

34. The electrochemical cell of claim 33, wherein the solvent is ethylene carbonate, propylene carbonate, diethylene carbonate, methylene carbonate, or a combination thereof.

35. The electrochemical cell of claim 33, wherein the lithium salt is LiPF₆, LiBOB, or LFTSi.

36. The electrochemical cell of claim 33, wherein the polymer is PVDF-HFP.

37. The method of claim 30, comprising applying a pressure of at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, or 320 PSI to the electrolyte separator and anode.

38. The method of claim 30, comprising applying a pressure of at least 320 PSI to the electrolyte separator and anode.

39. The electrolyte separator of claim 1, made by a process which comprises a step of annealing the top or bottom surface at a temperature of 350°

C. or higher.

40. An electrolyte separator, characterized by the chemical formula Li_xLa₃Zr₂O₁₂+yAl₂O₃, wherein 3≤

x≤

8 and 0≤

y≤

1 and having a top or bottom surface that has less than 5 atomic % of an amorphous material comprising carbon and oxygen.