Vitreous solid electrolyte sheets of Li ion conducting sulfur-based glass and associated structures, cells and methods
A lithium ion-conductive solid electrolyte including a freestanding inorganic vitreous sheet of sulfide-based lithium ion conducting glass is capable of high performance in a lithium metal battery by providing a high degree of lithium ion conductivity while being highly resistant to the initiation and/or propagation of lithium dendrites. Such an electrolyte is also itself manufacturable, and readily adaptable for battery cell and cell component manufacture, in a cost-effective, scalable manner.
1. A standalone Li ion conductive solid electrolyte separator comprising:
a freestanding substantially amorphous solid electrolyte wall structure that is dense, inorganic and highly conductive of Li ions, the wall structure comprising:
i) a continuous Li ion conducting inorganic amorphous material phase with room temperature Li ion conductivity ≥10 −5 S/cm;
ii) first and second opposing principal sides and associated surfaces; and
iii) a microstructure devoid of contiguous crystalline grain boundaries and powder particle boundaries extending between the opposing principal side surfaces;
wherein the inorganic amorphous material phase is a Li ion conducting sulfur-based glass having,
S (sulfur) and Li (lithium) as constituent elements of the glass; and
at least one more constituent element of the glass selected from the group consisting of P (phosphorous), B (boron), Ge (germanium), and Si (silicon);
wherein the wall structure is a freestanding vitreous sheet of the Li ion conducting sulfur-based glass; and
wherein the vitreous sheet has substantially parallel lengthwise edges.
2. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the area of the vitreous sheet is at least 100 cm 2 .
3. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the length of the vitreous sheet is at least 25 cm.
4. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the vitreous sheet has length (l) to width (w) area aspect ratio (l/w) of no less than 10, and the sheet width (w) is no less 1 cm.
5. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the first principal side comprises a liquid-like surface.
6. The standalone Li ion conductive solid electrolyte separator of claim 5 , wherein the liquid-like first principal side surface lacks flaws having a flaw depth extension (Γ) of more than 5 μm.
7. The standalone Li ion conductive solid electrolyte separator of claim 6 , wherein the liquid-like first principal side surface lacks flaws having a flaw depth extension (Γ) greater than 1% of the sheet thickness.
8. The standalone Li ion conductive solid electrolyte separator of claim 5 , wherein the liquid-like first principal side surface is characterizable as having a threshold current density greater than 1 mA/cm 2 .
9. The standalone Li ion conductive solid electrolyte separator of claim 8 , wherein the threshold current density is greater than 2 mA/cm 2 .
10. The standalone lithium ion conductive solid electrolyte separator of claim 5 , wherein the liquid-like first principal side surface has average surface roughness Ra≤0.05 um.
11. The standalone lithium ion conductive solid electrolyte separator of claim 5 , wherein the liquid-like first principal side surface has average surface waviness Wa≤5 μm.
12. The standalone Li ion conductive solid electrolyte separator of claim 5 , wherein the first principal side surface is untouched by an abrasive solid surface.
13. The standalone Li ion conductive solid electrolyte separator of claim 12 , wherein the second principal side surface is untouched by an abrasive solid surface.
14. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the first and second principal side surfaces of the vitreous sheet, in its virgin state as a solid, are untouched by a foreign solid body surface.
15. The standalone Li ion conductive solid electrolyte separator of claim 14 , wherein the vitreous sheet, in its virgin state as a solid, has a uniform thickness no greater than 100 μm thick.
16. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the first and second principal sides of the vitreous sheet are essentially free of surface microvoids.
17. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the vitreous sheet is essentially free of internal micropores.
18. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the first principal side surface of the vitreous sheet of sulfur-based glass is chemically compatible in direct contact with Li metal.
19. The standalone lithium ion conductive solid electrolyte separator of claim 18 , wherein the vitreous sheet has ASR of no more than 200 Ω-cm 2 , as measured using non-blocking lithium metal electrodes in direct contact with the first and second principal opposing side surfaces.
20. The standalone lithium ion conductive solid electrolyte separator of claim 19 , wherein the sulfur-based glass comprises B (boron) as a constituent element and is substantially devoid of P (phosphorous).
21. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the sulfur-based glass is of the type selected from the group consisting of Li 2 S—YS n , Li 2 S—YS n —YO n , and combinations thereof; wherein Y is selected from the group consisting of Ge, Si, As, B, or P; and n=2, 3/2 or 5/2.
22. The standalone Li ion conductive solid electrolyte separator of claim 1 , wherein the sulfur-based glass comprises Li 2 S as a glass modifier and one or more glass formers selected from the group consisting of P 2 S 5 , P 2 O 5 , SiS 2 , SiO 2 , B 2 S 3 and B 2 O 3 .
23. The standalone Li ion conductive solid electrolyte separator of claim 1 , further comprising electrically insulating edge-protector elements, which interface with the substantially parallel lengthwise edges of the vitreous sheet.
24. The standalone Li ion conductive solid electrolyte component of claim 1 , wherein the vitreous sheet is in the form of a continuous web of sulfur-based glass having length >100 cm.
25. The standalone Li ion conductive solid electrolyte component of claim 24 , wherein the continuous web is in the form of a coil.
26. A standalone Li ion conductive solid electrolyte separator comprising:
a freestanding substantially amorphous solid electrolyte wall structure that is dense, inorganic and highly conductive of Li ions, the wall structure comprising:
i) a continuous Li ion conducting inorganic amorphous material phase with room temperature Li ion conductivity ≥10 −5 S/cm;
ii) first and second opposing principal sides and associated surfaces; and
iii) a microstructure devoid of contiguous crystalline grain boundaries and powder particle
boundaries extending between the opposing principal side surfaces;
wherein the inorganic amorphous material phase is a Li ion conducting sulfur-based glass having,
S (sulfur) and Li (lithium) as constituent elements of the glass; and
at least one more constituent element of the glass selected from the group consisting of P (phosphorous), B (boron), Ge (germanium), and Si (silicon);
wherein the wall structure is a freestanding vitreous sheet of the Li ion conducting sulfur-based glass; and
wherein the vitreous sheet of sulfur-based glass has a uniform thickness of no more than 100 μm.
27. A standalone Li ion conductive solid electrolyte separator comprising:
a freestanding substantially amorphous solid electrolyte wall structure that is dense, inorganic and highly conductive of Li ions, the wall structure comprising:
i) a continuous Li ion conducting inorganic amorphous material phase with room temperature Li ion conductivity ≥10 −5 S/cm;
ii) first and second opposing principal sides and associated surfaces; and
iii) a microstructure devoid of contiguous crystalline grain boundaries and powder particle boundaries extending between the opposing principal side surfaces;
wherein the inorganic amorphous material phase is a Li ion conducting sulfur-based glass having,
S (sulfur) and Li (lithium) as constituent elements of the glass; and
at least one more constituent element of the glass selected from the group consisting of P (phosphorous), B (boron), Ge (germanium), and Si (silicon);
wherein the wall structure is a freestanding vitreous sheet of the Li ion conducting sulfur-based glass;
wherein the vitreous sheet is essentially free of internal micropores; and
wherein the vitreous sheet is wound about a spool for storage, the spool having diameter of no more than 20 cm.
28. A lithium battery cell comprising:
a positive electrode;
a negative electrode; and
a solid electrolyte separator disposed between the electrodes, wherein the solid electrolyte separator is a standalone Li ion conductive solid electrolyte separator comprising:
a freestanding substantially amorphous solid electrolyte wall structure that is dense, inorganic and highly conductive of Li ions, the wall structure comprising:
i) a continuous Li ion conducting inorganic amorphous material phase with room temperature Li ion conductivity ≥10 −5 S/cm;
ii) first and second opposing principal sides and associated surfaces; and
iii) a microstructure devoid of contiguous crystalline grain boundaries and powder particle boundaries extending between the opposing principal side surfaces.
29. The cell of claim 28 , wherein the wall structure is a freestanding vitreous sheet of the Li ion conducting sulfur-based glass.
30. The cell of claim 29 , wherein the vitreous sheet has substantially parallel lengthwise edges.
31. A method for making a standalone Li ion conductive solid electrolyte separator, the method comprising making a vitreous solid sheet of Li ion conducting sulfur-based glass; wherein the method for making the vitreous sheet comprises the steps of:
a. forming a continuous fluid sheet of an inorganic sulfur-based glass at a temperature above Tg of the glass, the fluid sheet having substantially parallel lengthwise edges and a center portion having first and second opposing principal side surfaces;
b. causing the continuous fluid sheet to flow with unbroken continuity;
c. solidifying the continuous fluid sheet by cooling it to a temperature below Tg; wherein the solidified fluid sheet of sulfur-based glass is vitreous, substantially amorphous, conductive of Li ions, and of unbroken continuity.
32. The method of claim 31 , wherein just prior to reaching a temperature at or below Tg, the first and second principal side surfaces are untouched by a foreign solid surface.
33. The method of claim 32 , wherein the center portion of the fluid sheet has uniform thickness (t) selected from the group consisting of 250 μm<t≤500 μm (±10%); 100 μm<t≤250 μm (±20%); 50 μm<t≤100 μm (±20%); 30 μm<t≤50 μm (±20%); and 10 μm<t≤30 μm (±20%).
34. The method of claim 32 wherein the solidified fluid sheet is at least 10 cm long.
35. The method of claim 34 , wherein the mole % of Li in the sulfur-based glass is ≥10%.
36. The method of claim 31 , further comprising the step of removing peripheral lengthwise edge portions of the sheet by laser cutting.
37. The method of claim 31 , wherein the fluid sheet of sulfur-based glass is a fluid stream of unbroken continuity that is derived directly from a liquid melt and caused to flow along its lengthwise dimension.
38. The method of claim 31 , wherein fluid sheet is a fluid stream of unbroken continuity that is not derived directly from a liquid melt.
39. The method of claim 31 , wherein the sulfur-based glass has a glass stability factor {T x -T g } of less than 50° C.
40. The method of claim 31 , wherein the vitreous solid sheet of Li ion conducting sulfur-based glass is essentially free of crystalline phases.
41. The method of claim 31 , further comprising the steps of:
i) selecting constituent elements of the sulfur-based glass, the constituent elements comprising S (sulfur), Li (lithium), and one or more of P (phosphorous), B (boron), Si (silicon), and O (oxygen); and
ii) adjusting the mole ratio of the constituent elements to maximize the liquidus viscosity, without decreasing the room temperature Li ion conductivity of the sheet below 10 −5 S/cm.
42. The method of claim 41 , wherein the adjusting step comprises not decreasing the room temperature Li ion conductivity below 10 −4 S/cm.
43. The method of claim 41 , wherein the liquidus viscosity is greater than 200 poise.
44. The method of claim 41 , wherein the adjusting step does not increase the vitreous solid sheet ASR to a value greater than 200 Ω-cm 2 , as measured between opposing principal side surfaces using non-blocking lithium metal electrodes.
45. The method of claim 31 , further comprising the steps of:
i) selecting constituent elements of the inorganic sulfur based Li ion conducting glass, the constituent elements comprising S (sulfur), Li (lithium), and one or more of P (phosphorous), B (boron), Si (silicon), and O (oxygen); and
ii) adjusting the mole ratio of the constituent elements to maximize the glass stability factor {T x −T g } of the sulfur-based glass, without decreasing the room temperature Li ion conductivity of the sheet below 10 −5 S/cm.
46. The method of claim 45 , wherein the room temperature Li ion conductivity does not decrease below 10 −4 S/cm.
47. The method of claim 45 , wherein the glass stability factor is greater than 50° C.