Membranes for electrochemical cells
Ionically conducting composite membranes are provided which include a solid-state ionically conducting material The ionically conducting composite membranes may be used in electrochemical cells. The solid-state ionically conducting material may be an electrochemically active material. In some electrochemical cells, the solid-state ionically conducting material may be in electronic communication with an external tab.
1. An electrochemical cell comprising:
a positive electrode comprising a positive electrode active material and a first current collector in electronic communication with the positive electrode active material, the first current collection further comprising a first external connection tab;
a negative electrode comprising a negative electrode active material and a second current collector in electronic communication with the negative electrode active material, the second current collector further comprising a second external connection tab;
a composite membrane disposed between the positive electrode and the negative electrode; the composite membrane being ionically conductive and comprising:
an active layer; wherein said active layer comprises an ionically conductive solid-state material;
a first ionically conductive separator positioned between the positive electrode and the ionically conductive solid-state material; and
a second ionically conductive separator positioned between the negative electrode and the ionically conductive solid-state material;
wherein the composite membrane further comprises a third external connection tab in electronic communication with the ionically conductive solid-state material; and
one or more electrolytes positioned between said positive electrode and said negative electrode; said one or more electrolytes capable of conducting ionic charge carriers; said one or more electrolytes including at least one liquid electrolyte disposed between the composite membrane and the positive electrode, the negative electrode or both the positive and negative electrodes;
wherein said ionically conductive solid-state material is in electronic communication with said third external connection configured to electronically activate said ionically conductive solid-state material so as to provide for an increase in the ionic conductivity of said ionically conductive solid-state material in response to application of a voltage or current between said ionically conductive solid-state material and one of said positive electrode and said negative electrode using said third external connection.
2. The electrochemical cell of claim 1 , wherein the ionically conductive solid-state material is in the form of a sheet, the sheet being substantially nonporous.
3. The electrochemical cell of claim 2 , wherein the ionically conductive solid-state material is from to 10 nm to 50 μm in thickness.
4. The electrochemical cell of claim 1 , wherein the ionically conductive solid-state material comprises a mixture of ionically conductive particles and electronically conductive particles.
5. The electrochemical cell of claim 1 , wherein the ionically conductive solid-state material is configured to be selectively electronically connected to and disconnected from the negative electrode.
6. The electrochemical cell of claim 1 , wherein the ionically conductive solid-state material is configured to be selectively electronically connected to and disconnected from the positive electrode.
7. The electrochemical cell of claim 1 , wherein the ionically conductive solid-state material is electrochemically active.
8. The electrochemical cell of claim 1 , wherein the ionically conductive solid-state material is a solid or gel comprising a material selected from the group consisting of carbon, lithium titanate, Li 2 O 2 , Li 2 O, titanium disulfide, iron phosphate, SiO2, V 2 O 5 , lithium iron phosphate, MnO 2 , Al 2 O 3 , TiO 2 , LiPF 6 , Li 3 P, Li 3 N, LiNO 3 , LiClO 4 , LiOH, PEO, P 2 O 5 , LIPON, LISICON, ThioLISICO, Ionic Liquids, Al, Cu, Ti, Stainless Steel, Iron, Ni, graphene oxide, PEDOT-PSS, and combinations thereof.
9. The electrochemical cell of claim 1 , wherein the electrochemical cell is a Li-ion or Na-ion cell.
10. The electrochemical cell of claim 1 , wherein said first ionically conductive separator is porous or perforated and wherein said second ionically conductive separator is porous or perforated.
11. The electrochemical cell of claim 1 , wherein the conductivity of said ionically conductive solid-state material is lithium titanate.
12. An electrochemical cell comprising:
a positive electrode;
a negative electrode;
a composite membrane layer positioned between the said electrodes comprising:
an active layer; wherein said active layer comprises at least one ionically conductive solid-state material;
wherein the composite membrane further comprises a third external connection tab in electronic communication with the ionically conductive solid-state material;
at least one ionically conductive separator positioned between the positive electrode or negative electrode and the ionically conductive solid-state material; and
one or more electrolytes positioned between said positive electrode and said negative electrode; said one or more electrolytes capable of conducting ionic charge carriers; said one or more electrolytes including at least one liquid electrolyte disposed between the composite membrane layer and the positive electrode, the negative electrode or both the positive and negative electrodes;
wherein said at least one ionically conductive solid-state material is in electronic communication with said third external connection configured to electronically activate said ionically conductive solid-state material activatable so as to provide for an increase in the ionic conductivity of said ionically conductive solid-state material in response to application of a voltage or current between said external connection tab and one of said positive electrode and said negative electrode using said third external connection.
13. The electrochemical cell of claim 12 , wherein the at least one ionically conductive solid-state material is in the form of a coating on at least one side of one of the electrodes.
14. The electrochemical cell of claim 12 , wherein the composite membrane layer is from 10 nm to 50 μm in thickness.
15. The electrochemical cell of claim 12 , wherein the at least one ionically conductive solid-state material has voltage ranges of reduction and oxidation, with values between the charge-discharge voltage limits of the said electrochemical cell.
16. The electrochemical cell of claim 12 , wherein the at least one ionically conductive solid-state material comprises a material selected from the group consisting of carbon, lithium titanate, Li 2 O 2 , Li 2 O, titanium disulfide, iron phosphate, SiO2, V 2 O 5 , lithium iron phosphate, MnO 2 , Al 2 O 3 , TiO 2 , LiPF 6 , Li 3 P, Li 3 N, LiNO 3 , LiClO 4 , LiOH, PEO, P 2 O 5 , LIPON, LISICON, ThioLISICO, Ionic Liquids, Al, Cu, Ti, Stainless Steel, Iron, Ni, graphene oxide, PEDOT-PSS, and combinations thereof.
17. The electrochemical cell of claim 12 , wherein the electrochemical cell is a Li-ion or Na-ion cell.
18. The electrochemical cell of claim 12 , wherein the at least one ionically conductive solid-state material is in the form of a coating on at least one side of one of an ionically conductive separator.
19. The electrochemical cell of claim 12 , wherein the ionically conductive solid-state material is electrochemically active.
20. The electrochemical cell of claim 12 , wherein the composite membrane layer comprises at least one solid-state binder material.
21. The electrochemical cell of claim 12 , wherein the composite membrane layer is porous.
22. The electrochemical cell of claim 12 , wherein the at least one ionically conductive separator is porous or perforated.
23. The electrochemical cell of claim 12 , wherein the conductivity of said ionically conductive solid-state material is lithium titanate.
24. A method for operating an electrochemical cell comprising steps of:
providing an electrochemical cell, the cell comprising:
a positive electrode comprising a positive electrode active material and a first current collector in electronic communication with the positive electrode active material, the first current collection further comprising a first external connection tab;
a negative electrode comprising a negative electrode active material and a second current collector in electronic communication with the negative electrode active material, the second current collector further comprising a second external connection tab;
a composite membrane disposed between the positive electrode and the negative electrode; the composite membrane being ionically conductive and comprising:
an active layer; wherein said active layer comprises an ionically conductive solid-state material;
a third external connection in electronic communication with said ionically conductive solid-state material;
a first ionically conductive separator positioned between the positive electrode and the ionically conductive solid-state material; and
a second ionically conductive separator positioned between the negative electrode and the ionically conductive solid-state material; and
one or more electrolytes positioned between said positive electrode and said negative electrode; said one or more electrolytes capable of conducting ionic charge carriers; said one or more electrolytes including at least one liquid electrolyte disposed between the composite membrane and the positive electrode, the negative electrode or both the positive and negative electrodes; and
applying a voltage or current between said ionically conductive solid-state material and one of said positive electrode and said negative electrode using said third external connection, thereby increasing an ionic conductivity of said ionically conductive solid-state material.
25. The method of claim 24 , wherein the conductivity of said ionically conductive solid-state material is lithium titanate.
26. A method for operating an electrochemical cell comprising steps of:
providing an electrochemical cell, the cell comprising:
a positive electrode;
a negative electrode;
a composite membrane layer positioned between the said electrodes comprising:
an active layer; wherein said active layer comprises at least one ionically conductive solid-state material in electronic communication with an external connection tab;
at least one ionically conductive separator positioned between the positive electrode or negative electrode and the ionically conductive solid-state material;
a third external connection in electronic communication with said ionically conductive solid-state material; and
one or more electrolytes positioned between said positive electrode and said negative electrode; said one or more electrolytes capable of conducting ionic charge carriers; said one or more electrolytes including at least one liquid electrolyte disposed between the composite membrane layer and the positive electrode, the negative electrode or both the positive and negative electrodes; and
applying a voltage or current between said ionically conductive solid-state material and one of said positive electrode and said negative electrode using said third external connection, thereby increasing an ionic conductivity of said ionically conductive solid-state material.
27. The method of claim 26 , wherein the conductivity of said ionically conductive solid-state material is lithium titanate.