Reference electrode assemblies including thin, porous current collectors and methods of manufacturing thin, porous current collectors
A method of manufacturing a component for a reference electrode assembly according to various aspects of the present disclosure includes providing a separator having first and second opposing surfaces. The method further includes sputtering a first current collector layer to the first surface via magnetron or ion beam sputtering deposition. A porosity of the separator is substantially unchanged by the sputtering. In one aspect, the method further includes sputtering a second current collector layer to the second surface via magnetron or ion beam sputtering deposition. In one aspect, the first current collector layer includes nickel and defines a first thickness of greater than or equal to about 200 nm to less than or equal to about 300 nm and the second current collector layer includes gold and defines a second thickness of greater than or equal to about 25 nm to less than or equal to about 100 nm.
1. A method of manufacturing a component for a reference electrode assembly, the method comprising:
providing a separator layer having a first surface and a second surface opposite the first surface, the separator layer being electrically insulating and ionically conductive; and
sputtering a first current collector layer directly to the first surface, the sputtering including magnetron sputtering deposition or ion beam sputtering deposition, wherein a porosity of the separator layer is substantially unchanged by the sputtering the first current collector layer, and the porosity after the sputtering is greater than or equal to about 50%.
2. The method of claim 1 , further comprising:
sputtering a second current collector layer to the second surface, the sputtering including magnetron sputtering deposition or ion beam sputtering deposition.
3. The method of claim 2 , wherein:
the first current collector layer comprises nickel and defines a first thickness of greater than or equal to about 200 nm to less than or equal to about 300 nm; and
the second current collector layer comprises gold and defines a second thickness of greater than or equal to about 25 nm to less than or equal to about 100 nm.
4. The method of claim 2 , further comprising applying an electroactive layer in contact with the second current collector layer.
5. The method of claim 2 , wherein the first current collector layer comprises nickel.
6. The method of claim 2 , wherein the first current collector layer defines a first thickness of greater than or equal to about 200 nm to less than or equal to about 300 nm.
7. The method of claim 6 , wherein a first variation in the second thickness is less than or equal to about 0.5 μm.
8. The method of claim 2 , wherein the second current collector layer comprises gold.
9. The method of claim 2 , wherein the second current collector layer defines a second thickness of greater than or equal to about 25 nm to less than or equal to about 100 nm.
10. The method of claim 9 , wherein a second variation in the third thickness is less than or equal to about 0.5 μm.
11. The method of claim 1 , further comprising:
prior to the sputtering, applying a mask layer to a first region of the first surface; and
after the sputtering, removing the mask layer from the first surface such that the first current collector layer is disposed in a second region of the first surface distinct from the first region.
12. The method of claim 11 , wherein the mask layer comprises metal, a plastic, cellulose, or a water-soluble composition.
13. The method of claim 11 , further comprising
coupling the mask layer to the separator layer by a magnet, a clamp, a temporary adhesive, or any combination thereof.
14. The method of claim 1 , wherein the sputtering comprises the magnetron sputtering deposition.
15. The method of claim 14 , wherein the magnetron sputtering deposition further includes cooling the separator layer concurrently with the sputtering.
16. The method of claim 14 , wherein:
a volumetric flow rate of a sputtering gas is greater than or equal to about 20 standard cubic centimeters per minute (sccm) to less than or equal to about 300 sccm;
a voltage is greater than or equal to about 30 V to less than or equal to about 300 V; and
a deposition pressure is greater than or equal to about 3 millitorr (mTorr) to less than or equal to about 32 mTorr.
17. The method of claim 1 , wherein the sputtering includes the ion beam sputtering deposition.
18. The method of claim 17 , wherein:
a sputtering rate is greater than or equal to about 1 nm/min to less than or equal to about 200 nm/min;
an ion energy is greater than or equal to about 100 eV to less than or equal to about 100 eV;
an ion current density is greater than or equal to about 0.1 mA/cm 2 to less than or equal to about 10 mA/cm 2 ; and
an angle of incidence is greater than or equal to about 20° to less than or equal to about 60°.
19. The method of claim 1 , wherein the separator layer is maintained at a temperature of less than or equal to about 25° C. during the sputtering.
20. The method of claim 1 , where the porosity is greater than or equal to about 70% to less than or equal to about 80%.