Ionic gel electrolyte, energy storage devices, and methods of manufacture thereof
An electrochemical cell includes solid-state, printable anode layer, cathode layer and non-aqueous gel electrolyte layer coupled to the anode layer and cathode layer. The electrolyte layer provides physical separation between the anode layer and the cathode layer, and comprises a composition configured to provide ionic communication between the anode layer and cathode layer by facilitating transmission of multivalent ions between the anode layer and the cathode layer.
1. A method of fabricating an electrochemical cell, comprising the steps of:
providing a first electrode ink and a second electrode ink;
providing liquid electrolyte ink;
printing a first electrode layer of the first electrode ink;
printing an electrolyte layer of the liquid electrolyte ink, wherein the electrolyte layer comprises a polymer into which at least one ionic liquid and at least one electrolyte salt have been imbibed; and
printing a second electrode layer of the second electrode ink;
wherein the electrolyte layer provides physical separation between the first electrode layer and second electrode layer to form an electrochemical cell;
wherein the electrolyte layer is configured to provide ionic communication between the first electrode layer and the second electrode layer by facilitating transmission of multivalent ions between the first electrode layer and the second electrode layer; and
wherein the electrolyte salt dissolved into the ionic liquid releases multivalent cations selected from ions of at least one of zinc, aluminum, magnesium and yttrium.
2. A method as recited in claim 1 , further comprising:
providing a current collector ink; and
printing a layer of current collector ink adjacent to one or more of the first electrode layer and the second electrode layer.
3. A method as recited in claim 1 , further comprising fabricating the electrochemical cell at ambient temperature and ambient pressure.
4. A method as recited in claim 3 , further comprising fabricating the electrochemical cell without the use of a vacuum or a forming gas.
5. A method as recited in claim 1 , wherein the inks are liquids selected from the group consisting of solutions, suspensions, and slurries.
6. A method as recited in claim 1 , wherein the first and second electrode inks comprise slurries of active electrode particles, polymer binder, optional additives, and a solvent(s).
7. A method as recited in claim 1 , wherein the polymer comprises one or more polymer(s) selected from the group consisting of poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), polyvinyl alcohol (PVA), poly(ethylene oxide) (PEO), poly(acrylo-nitrile) (PAN), poly(methyl methacrylate) (PMMA), epoxy derivatives, and silicone derivatives.
8. A method as recited in claim 1 , wherein the ionic liquid is a room temperature salt having cations selected from the group consisting of imidazolium, pyrrolidinium, ammonium, pyridinium, piperidinium, phosphonium, and sulfonium.
9. A method as recited in claim 8 , wherein the ionic liquid is a room temperature salt having anions selected from the group consisting of chlorides, tetrafluoroborate (BF4-), trifluoroacetate (CF3CO2-), trifluoromethansulfonate (CF3SO3-), hexafluorophosphate (PF6-), bis(trifluoromethylsulfonyl)amide (NTf2-), and bis(fluorosulfonyl)imide (N(SO2F)2-).
10. A method as recited in claim 1 , wherein the first electrode layer comprises a component selected from the group consisting of zinc, aluminum, magnesium, and yttrium.
11. A method as recited in claim 1 , wherein the second electrode layer comprises particles of a metal oxide.
12. A method as recited in claim 1 , wherein at least one of said printing steps is done using a direct write dispenser method.
13. A method as recited in claim 1 , wherein at least one of said printing steps is done using a method selected from the following methods: screen-printing, gravure printing, pad printing, ink jet printing, flexographic coating, spray coating, ultrasonic spray coating, or slot die coating.
14. A method as recited in claim 1 , wherein the electrolyte salt comprises anions selected from the group consisting of chlorides, tetrafluoroborate (BF4-), trifluoroacetate (CF3CO2-), trifluoromethansulfonate (CF3SO3-), hexafluorophosphate (PF6-), bis(trifluoromethylsulfonyl)amide (NTf2-), and bis(fluorosulfonyl)imide (N(SO2F)2-).
15. A method as recited in claim 1 , further comprising printing the layer of electrolyte with a thickness between approximately 1 μm and 30 μm.
16. A method as recited in claim 1 , further comprising depositing the first electrode layer, the second electrode layer and the electrolyte layer on a substrate in a liquid form.
17. A method as recited in claim 16 , further comprising solidifying the first electrode layer, the second electrode layer and the electrolyte layer to at least a semi-solid state.
18. A method as recited in claim 1 , wherein the first electrode layer, the second electrode layer and the electrolyte layer are flexible.
19. A method as recited in claim 1 , wherein the electrolyte layer is substantially non- volatile.
20. A method as recited in claim 1 , further comprising fabricating the electrochemical cell with substantially no hermetic sealing.
21. A method as recited in claim 1 , wherein the electrochemical cell is conformable to a non-planar substrate without damage.
22. A method as recited in claim 1 , wherein, in an electrochemical cell, the electrolyte layer maintains a leakage current density of less than 25 μA/cm 2 while being exposed to ambient air at room temperature for a period greater than 1 week.