Low-temperature ceramic-polymer nanocomposite solid state electrolyte
Ceramic-polymer film includes a polymer matrix, plasticizers, a lithium salt, and a ceramic nanoparticle, LLZO: Al x Li 7-x La 3 Zr 1.75 Ta 0.25 O 12 where x ranges from 0 to 0.85. The nanoparticles have diameters that range from 20 to 2000 nm and the film has an ionic conductivity of greater than 1×10 −4 S/cm (−20° C. to 10° C.) and larger than 1×10 −3 S/cm (≥20° C.). Using a combination of selected plasticizers to tune the ionic transport temperature dependence enables the battery based on the ceramic-polymer film to be operable in a wide temperature window (−40° C. to 90° C.). Large size nanocomposite film (area ≥8 cm×6 cm) can be formed on a substrate and the concentration of LLZO nanoparticles decreases in the direction of the substrate to form a concentration gradient over the thickness of the film. This large size film can be employed as a non-flammable, solid-state electrolyte for lithium electrochemical pouch cell and further assembled into battery packs.
1. A ceramic-polymer film that comprises: a polymer matrix which comprises 12.4 wt % of the film; a plasticizer which comprises 37.3 wt % of the film; a lithium salt which comprises 33.2 wt % of the film; and ceramic nanoparticles having the formula Al x Li 7-x La 3 Zr 1.75 Ta 0.25 O 12 where x ranges from greater than 0 to 0.85 (LLZO), wherein the ceramic nanoparticles have diameters that range from 100 to 2000 nm and comprise 16.6 wt % of the film, wherein the film has an ionic conductivity of higher than 1×10 −4 S/cm when measured at a temperature in the range of −20° C. to 10° C. and wherein the film has an ionic conductivity of higher than 1×10 −3 S/cm when measured at a temperature 20° C. or higher.
2. The film of claim 1 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
3. The film of claim 1 wherein the film is free standing and has a thickness that ranges from 100 to 900 μm.
4. The film of claim 1 wherein the film which has a first surface and a second surface and the concentration of LLZO nanoparticles in the film increases in the direction from the first surface to the second surface.
5. The film of claim 1 wherein the plasticizer consists essentially of a mixture of PC and DMSO.
6. The film of claim 1 where x ranges from 0.15 to 0.85.
7. The film of claim 6 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
8. The film of claim 6 wherein the plasticizer consists essentially of a mixture of PC and DMSO.
9. The film of claim 1 where x ranges from 0.15 to 0.85.
10. An electrochemical cell which comprises: an anode; a cathode; and interposed therebetween a solid-electrolyte that is a film which comprises:
a polymeric matrix which comprises 12.4 wt % of the film;
a plasticizer which comprises 37.3 wt % of the film;
a lithium salt which comprises 33.2 wt % of the film; and
ceramic nanoparticles having the formula Al x Li 7-x La 3 Zr 1.75 Ta 0.25 O 12 where x ranges from greater than 0 to 0.85 (LLZO), and wherein the ceramic nanoparticles have diameters that range from 100 to 2000 nm and comprise 16.6 wt % of the film, wherein the film is free standing and has a thickness that ranges from 100 to 900 μm.
11. The electrochemical cell of claim 10 wherein the solid-electrolyte is a film which has a first surface and a second surface and the concentration of LLZO nanoparticles in the film increases in the direction from the first surface to the second surface.
12. The electrochemical cell of claim 10 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
13. The electrochemical cell of claim 10 wherein the plasticizer consists essentially of a mixture of PC and DMSO.
14. The electrochemical cell of claim 10 where x ranges from 0.15 to 0.85.
15. The electrochemical cell of claim 14 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
16. The electrochemical cell of claim 14 wherein the plasticizer consists essentially of a mixture of PC and DMSO.
17. The electrochemical cell of claim 10 where x ranges from 0.15 to 0.85.
18. A process for preparing an electrochemical cell which comprises:
(a) providing a cathode;
(b) providing an anode; and
(c) forming a solid-electrolyte between the cathode and anode wherein the solid electrolyte is a film that comprises: (i) a polymeric matrix that comprises 12.4 wt % of the film, (ii) a plasticizer that comprises 37.3 wt % of the film, (iii) a lithium salt that comprises 33.2 wt % of the film; and (iv) ceramic nanoparticles having the formula Al x Li 7-x La 3 Zr 1.75 Ta 0.25 O 12 where x ranges from 0 to 0.85 (LLZO), and wherein the ceramic nanoparticles have diameters that range from 100 to 2000 nm and comprise 16.6 wt % of the film and wherein the LLZO is synthesized by (i) mixing stoichiometric amounts of LiOH.H 2 O, La 2 O 3 , ZrO 2 , Al 2 O 3 and Ta 2 O 5 in a first liquid form a mixture, (ii) ball milling the mixture to form a slurry, (iii) drying the slurry to form a dried material, and (vi) calcining the dried material to decompose the LiOH.H 2 O to form an as-calcined powder, (iv) ball milling the as-calcined powder in a second liquid to form a ball-milled material, and (v) drying the ball-milled material to form dried powders and (v) sintering the dried powders at a temperature from 800 to 1150° C.
19. The process of claim 18 comprising calcining the dried material at a calcine temperature of 950 to 1050° C. to yield LLZO nanoparticles with diameters of 100 nm to 2 microns and whereby employing higher calcine temperatures yields nanoparticles with larger diameters.
20. The process of claim 18 wherein the plasticizer consists essentially of (i) EC (ii) a mixture of EC and DMSO or (iii) a mixture of PC and DMSO.
21. The process of claim 20 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
22. The process of claim 20 wherein the plasticizer consists essentially of a mixture of PC and DMSO.
23. The process of claim 18 where x is greater than 0.
24. The process of claim 18 where x ranges from 0.15 to 0.85.
25. The process of claim 18 wherein the film is free standing and has a thickness that ranges from 100 to 900 μm.
26. The process of claim 18 wherein the film is formed on an electrode.
27. The process of claim 18 where x is greater than 0.
28. The process of claim 27 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
29. The process of claim 27 wherein the plasticizer consists essentially of a mixture of PC and DMSO.
30. The process of claim 18 where x is 0.15 to 0.85.
31. The process of claim 30 wherein the plasticizer consists essentially of a mixture of EC and DMSO.
32. The process of claim 30 wherein the plasticizer consists essentially of a mixture of PC and DMSO.