Glass ceramic with ion-conducting residual glass phase and process for the production thereof
The present disclosure relates to a lithium ion-conducting glass ceramic which comprises a residual glass phase that is also ion-conducting, a process for the production thereof as well as its use in a battery. The glass ceramic according to the present disclosure comprises a main crystal phase which is isostructural to the NaSICon crystal phase, wherein the composition can be described with the following formula: Li 1+x−y M y 5+ M x 3+ M 2−x−y 4+ (PO 4 ) 3 , wherein x is greater than 0 and at most 1, as well as greater than y. Y may take values of between 0 and 1. Here, the following boundary condition has to be fulfilled: (1+x−y)>1. Here, M represents a cation with the valence of +3, +4 or +5. M 3+ is selected from Al, Y, Sc or B, wherein at least Al as trivalent cation is present. Independently thereof, M 4+ is selected from Ti, Si or Zr, wherein at least Ti as tetravalent cation is present. Independently thereof, M 5+ is selected from Nb, Ta or La.
1. A lithium ion-conductive glass ceramic, wherein the glass ceramic comprises a crystal phase having the chemical composition
Li 1+x M x 3+ M 2−x 4+ (PO 4 ) 3 ,
wherein M 3+ =Al 3+ only and, M 4+ =Ti 4+ only,
wherein the glass ceramic comprises a glass phase with an ionic conductivity of higher than 10 −5 S/cm,
wherein the composition of the glass phase comprises Li 2 O, P 2 O 5 and B 2 O 3 , and the content of B 2 O 3 in the glass ceramic is from 0.2 mole % to 4 mole % and
wherein the Al 3+ forms Al 2 O 3 in the crystal phase and the Ti 4+ forms TiO 2 in the crystal phase, and
wherein x is selected so that the ratio of Al 2 O 3 /Li 2 O in the glass ceramic has a value of between >0 and 0.25.
2. The glass ceramic according to claim 1 , wherein after the glass ceramic is ceramicized and/or sintered at a temperature of <1000° C., the glass ceramic has a total conductivity of higher than 10 −4 S/cm at 22° C.
3. The glass ceramic according to claim 1 , wherein after the glass ceramic is ceramicized and/or sintered at a temperature of <900° C. the glass ceramic has a total conductivity of higher than 10 −4 S/cm at 22° C.
4. The glass ceramic according to claim 1 , wherein the glass phase consists essentially of the components Li 2 O, B 2 O 3 and P 2 O 5 .
5. The glass ceramic according to claim 1 , wherein the content of B 2 O 3 is from 0.3 mole % to 3 mole %.
6. The glass ceramic according to claim 1 , wherein the content of B 2 O 3 is from 0.5 mole % to 2.5 mole %.
7. The glass ceramic according to claim 1 , wherein the ratio of Al 2 O 3 /Li 2 O is less than 0.24.
8. The glass ceramic according to claim 1 , wherein the ratio of Al 2 O 3 /Li 2 O is less than 0.22.
9. The glass ceramic according to claim 1 , wherein the glass ceramic comprises the following composition in mole %:
1-6% of Al 2 O 3 ,
12-28% of Li 2 O,
32-42% of P 2 O 5 ,
28-45% of TiO 2 ,
0.2%<B 2 O 3 <4%.
10. The glass ceramic according to claim 1 , wherein the glass ceramic comprises the following composition in mole %:
2-5% of Al 2 O 3 ,
15-20% of Li 2 O,
34-40% of P 2 O 5 ,
36-42% of TiO 2 ,
0.5%<B 2 O 3 <2.5%.
11. The glass ceramic according to claim 1 , wherein the glass ceramic is substantially free of halides and/or arsenic and/or antimony and/or cadmium and/or chromium.
12. The glass ceramic according to claim 1 , wherein the glass ceramic is free of GeO 2 .
13. The glass ceramic according to claim 1 , wherein the glass ceramic is free of GaO 2 .
14. The glass ceramic according to claim 1 , wherein the glass ceramic has a content of Fe 2 O 3 that is less than 0.2 mole %.
15. The glass ceramic according to claim 1 , wherein the glass ceramic has a content of Fe 2 O 3 that is less than 0.1 mole %.
16. The glass ceramic according to claim 1 , wherein, when the glass ceramic is in contact with a polymer electrolyte, the glass ceramic has a transfer resistance of lower than 1000 Ω/cm 2 .
17. A process for the production of the glass-ceramic of claim 1 , the method comprising the steps of:
a) creating a starting glass by melting raw materials and homogenizing the starting glass,
b) casting and cooling the starting glass,
c) ceramicizing the starting glass at temperatures of between 750-1000° C.,
d) grinding the ceramicized starting glass to a powder, and
e) sintering the powder.
18. The process for the production of a glass-ceramic electrolyte material according to claim 17 , wherein, during the ceramicizing step c), the starting glass is ceramicized at temperatures of between 850-950° C.
19. The process for the production of a glass-ceramic electrolyte material according to claim 17 , wherein, before the sintering step e), the powder is mixed with an organic material.
20. The process for the production of a glass-ceramic electrolyte material according to claim 17 , wherein, before the sintering step e), the powder is mixed with a polymer.
21. A battery comprising the glass ceramic of claim 1 as a constituent, as an electrolyte, as part of an electrode, as an additive for a liquid electrolyte, as a constituent of a polymer electrolyte, as a constituent of a composite electrolyte, or as a coating on an electrode or a separator.
22. A lithium ion-conductive glass ceramic, wherein the glass ceramic comprises a crystal phase having the chemical composition
Li 1+x M x 3+ M 2−x 4+ (PO 4 ) 3 ,
wherein M 3+ =Al 3+ only and M 4+ =Ti 4+ only,
wherein the glass ceramic comprises a glass phase with an ionic conductivity of higher than 10 −5 S/cm,
wherein the composition of the glass phase comprises Li 2 O, P 2 O 5 and B 2 O 3 , and
wherein the Al 3+ forms Al 2 O 3 in the crystal phase and the Ti 4+ forms TiO 2 in the crystal phase, and
wherein x is selected so that the ratio of Al 2 O 3 /Li 2 O in the glass ceramic has a value of between >0 and 0.25,
wherein the glass ceramic comprises the following composition in mole %:
2-5% of Al 2 O 3 ,
15-20% of Li 2 O,
34-40% of P 2 O 5 ,
36-42% of TiO 2 ,
0.5%<B 2 O 3 <2.5%,
and wherein the glass ceramic is free of GeO 2 .