Lithium ion conducting sulfide glass fabrication
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. Such an electrolyte is also manufacturable, and readily adaptable for battery cell and cell component manufacture, in a cost-effective, scalable manner using an automated machine based system, apparatus and methods based on inline spectrophotometry to assess and inspect the quality of such vitreous solid electrolyte sheets and associated components. Suitable manufacturing methods can involve multi-stage thinning of a sulfide glass preform that includes a first thinning operation that involves applying a compressive force onto the preform to form a glass sheet and a second thinning operation that involves applying a tensile force on the as-formed glass sheet (e.g., drawing the sheet by pulling).
1. A method of making a dense Li ion conducting sulfide glass separator sheet, the method comprising:
providing a glass preform having thickness t i and width w i ;
applying a compressive force onto the preform to decrease its thickness and thus form a glass sheet precursor of thickness t ii , wherein t ii <t i ;
applying a tensile force onto the glass sheet precursor to decrease its thickness and thus form a dense Li ion conducting sulfide glass separator sheet of thickness t f , wherein t f <100 um and t f <t ii ; and
wherein the Li ion conductivity of the sulfide glass is at least 10 −5 S/cm at room temperature.
2. The method of claim 1 , further comprising providing the glass preform to a drawdown apparatus for continuous multi-stage drawing of sulfide glass solid electrolyte sheet, wherein the apparatus includes two or more thinning stages: i) a first thinning stage that uses compressive force for glass thinning, and ii) a second thinning stage that uses tensile force for glass thinning.
3. The method of claim 2 , wherein the apparatus is a slot-draw apparatus comprising a melting vessel and slot for forming a fluid glass preform.
4. The method of claim 2 , wherein the apparatus is an extrusion-draw apparatus comprising an extrusion die for forming an extruded glass preform.
5. The method of claim 2 , wherein the apparatus is a preform draw apparatus, wherein the preform is a block of the Li ion conducting sulfide glass.
6. A method of making a dense Li ion conducting sulfide glass separator sheet, the method comprising:
providing a preform of a sulfide glass having thickness (t i ) and width (w i ), wherein the Li ion conductivity of the sulfide glass is at least 10 −5 S/cm at room temperature;
applying a compressive force onto the preform to make a precursor sheet of the sulfide glass, wherein the width of the precursor sheet (w ii ) is greater than the width of the solid preform (w i ) and the thickness of the precursor sheet (t ii ) is less than the thickness of the preform (t i );
applying a tensile force onto the precursor sheet to draw it down to a Li ion conducting sulfide glass separator sheet having thickness (t f ) and width (w f ), wherein t f is not greater than 50 um.
7. The method of claim 6 , wherein t f <t ii <t i and w ii >w i and w f <w ii .
8. The method of claim 6 , wherein the preform is a solid preform, and further comprising softening the solid preform by heating it to a temperature above the glass transition of the sulfide glass prior to applying the compressive force onto the softened solid preform to make the precursor sheet of the sulfide glass.
9. The method of claim 8 , wherein t f <t ii <t i and w ii >w i and w f <w ii .
10. The method of claim 9 , wherein the thickness of the Li ion conducting sulfide glass separator sheet is not greater than 30 um.
11. The method of claim 10 , wherein the thickness of the Li ion conducting sulfide glass separator sheet is not greater than 20 um.
12. The method of claim 6 , wherein the preform is a fluid glass preform wherein the compressive force onto the fluid glass preform to make the precursor sheet of the sulfide glass.
13. The method of claim 12 , wherein t f <t ii <t i and w ii >w i and w f <w ii .
14. The method of claim 12 , wherein the thickness of the Li ion conducting sulfide glass separator sheet is not greater than 30 um.
15. The method of claim 14 , wherein the thickness of the Li ion conducting sulfide glass separator sheet is not greater than 20 um.
16. A method of making a dense Li ion conducting sulfide glass separator sheet, the method comprising:
extruding a sulfide glass into a preform having thickness (t i ) and width (w i ), wherein the Li ion conductivity of the sulfide glass is at least 10 −5 S/cm at room temperature;
applying a compressive force onto the extruded glass preform to make a precursor sheet of the sulfide glass, wherein the width of the precursor sheet (w ii ) is greater than the width of the solid preform (w i ) and the thickness of the precursor sheet (t ii ) is less than the thickness of the preform (t i );
applying a tensile force onto the precursor sheet to draw it down to a Li ion conducting sulfide glass separator sheet having thickness (t f ) and width (w f ), wherein t f is not greater than 50 um.
17. The method of claim 16 , wherein t f <t ii <t i and w ii >w i and w f <w ii .
18. The method of claim 16 , wherein the thickness of the Li ion conducting sulfide glass separator sheet is not greater than 30 um.
19. The method of claim 18 , wherein the thickness of the Li ion conducting sulfide glass separator sheet is not greater than 20 um.