Zinc electrodes for batteries
A method of: providing an emulsion having a zinc powder and a liquid phase; drying the emulsion to form a sponge; sintering the sponge in an inert atmosphere to form a sintered sponge; heating the sintered sponge in an oxidizing atmosphere to form an oxidized sponge having zinc oxide on the surface of the oxidized sponge; and heating the oxidized sponge in an inert atmosphere at above the melting point of the zinc. A method of: providing an emulsion comprising a zinc powder and a liquid phase; placing the emulsion into a mold, wherein the emulsion is in contact with a metal substrate; and drying the emulsion to form a sponge.
1. A method comprising:
providing a mixture comprising a zinc powder and a liquid phase emulsion;
drying the emulsion to form a sponge;
sintering the sponge in an inert atmosphere to form a sintered sponge;
heating the sintered sponge in an oxidizing atmosphere to form an oxidized sponge comprising zinc oxide on the surface of the oxidized sponge; and
heating the oxidized sponge in an inert atmosphere at above the melting point of the zinc.
2. The method of claim 1 , wherein the sintering is performed at at least two thirds of the melting point of the zinc and below the melting point of the zinc.
3. The method of claim 1 , wherein heating the sintered sponge is performed at a temperature greater than the melting point of the zinc.
4. The method of claim 1 , wherein heating the oxidized sponge is performed at a temperature greater than the melting point of the zinc.
5. The method of claim 1 , wherein the sintering, heating the sintered sponge, and heating the oxidized sponge are each performed with dwell times of at least 30 minutes.
6. The method of claim 1 , wherein the zinc powder or liquid phase comprises an additive that suppresses gas evolution and corrosion of the sponge.
7. The method of claim 6 , wherein the additive comprises bismuth and indium.
8. The method of claim 1 , wherein the liquid phase emulsion comprises water and decane.
9. The method of claim 1 , wherein the emulsion comprises an emulsifier and an emulsion stabilizer.
10. The method of claim 9 , wherein the emulsifier is sodium dodecyl sulfate and emulsion stabilizer is carboxymethylcellulose.
11. The method of claim 1 , wherein the sintering is performed under argon at a peak temperature of 200-410° C.
12. The method of claim 1 , wherein the heating is performed in air at a peak temperature greater than 420° C.
13. The method of claim 1 , further comprising:
electrochemically reducing the zinc oxide to form a zinc metal sponge.
14. The method of claim 13 , wherein the zinc oxide is reduced by applying a negative voltage to the oxidized sponge until the open-circuit potential vs. zinc is less than 5 mV.
15. A method comprising:
providing a mixture comprising a zinc powder and a liquid phase emulsion;
placing the mixture into a mold, wherein the mixture is in contact with a metal substrate;
drying the mixture to form a sponge;
removing the mold from the sponge and substrate;
sintering the sponge in an inert atmosphere to form a sintered sponge;
heating the sintered sponge in an oxidizing atmosphere to form an oxidized sponge comprising zinc oxide on the surface of the oxidized sponge; and
heating the oxidized sponge in an inert atmosphere at above the melting point of the zinc.
16. The method of claim 15 , wherein the substrate is a metal mesh.
17. The method of claim 16 , wherein the mesh has an average opening size that is less than the d 50 particle size of the zinc powder.
18. The method of claim 15 , wherein the substrate is a metal foil.
19. The method of claim 15 , wherein the substrate comprises tin or tin-coated copper.
20. The article made by the method of claim 15 .
21. The method of claim 15 , further comprising electrochemically reducing the zinc oxide to form a zinc metal sponge.
22. The article made by the method of claim 21 .