Alkaline electrochemical cells comprising increased zinc oxide levels
Alkaline electrochemical cells are provided, wherein dissolved zinc oxide or zinc hydroxide is included at least in the free electrolyte solution, and/or solid zinc oxide or zinc hydroxide is included in the anode, so as to slow formation of a zinc oxide passivation layer on a zinc electrode. Methods for preparing such cells are also provided.
1. An alkaline electrochemical cell, comprising:
a) a container; and
b) an electrode assembly disposed within the container and comprising a cathode, an anode, a separator located between the cathode and the anode, and a free electrolyte solution;
wherein the anode comprises 1) solid zinc, 2) solid particulate zinc oxide or solid particulate zinc hydroxide in an amount of from about 0.2 to 5 weight percent, and 3) dissolved zinc oxide or dissolved zinc hydroxide;
wherein the free electrolyte solution comprises dissolved zinc oxide or dissolved zinc hydroxide;
wherein the anode comprises a gelled electrolyte, wherein the gelled electrolyte is prepared by combining a gelling agent with a first aqueous alkaline electrolyte solution, wherein the first aqueous alkaline electrolyte solution comprises an alkaline metal hydroxide electrolyte in an amount less than 30 weight percent and dissolved zinc oxide in an amount of ≥2.5 weight percent; and
wherein the alkaline electrochemical cell is a primary alkaline electrochemical cell.
2. The alkaline electrochemical cell of claim 1 , wherein the anode comprises solid particulate zinc oxide and dissolved zinc oxide, and the free electrolyte solution comprises dissolved zinc oxide.
3. The alkaline electrochemical cell of claim 2 , wherein the free electrolyte solution comprises dissolved zinc oxide in an amount between 1.5 and 2.5 weight percent.
4. The alkaline electrochemical cell of claim 1 , wherein the cathode comprises a second aqueous alkaline electrolyte solution, wherein the second aqueous alkaline electrolyte solution comprises an alkaline metal hydroxide electrolyte and dissolved zinc oxide.
5. The alkaline electrochemical cell of claim 4 , wherein the second aqueous alkaline electrolyte solution comprises dissolved zinc oxide in an amount of ≥2.5 weight percent.
6. The alkaline electrochemical cell of claim 1 , wherein the total dissolved zinc oxide weight percent in the electrochemical cell's full cell electrolyte solution is about 1.5-4.5 weight percent.
7. The alkaline electrochemical cell of claim 1 , wherein the electrochemical cell's full cell electrolyte is greater than 40% saturated with dissolved zinc oxide.
8. The alkaline electrochemical cell of claim 1 , wherein the solid particulate zinc oxide or solid particulate zinc hydroxide is substituted and comprises a cation substituent or an anion substituent, wherein the substituted solid particulate zinc oxide or substituted solid particulate zinc hydroxide is less soluble than unsubstituted solid particulate zinc oxide or unsubstituted solid particulate zinc hydroxide.
9. The alkaline electrochemical cell of claim 8 , wherein the substituted solid particulate zinc oxide has the formula Zn 1-x Y x O or Zn 1-x Y x (OH) 2 , wherein Y is at least one cation substituent, and 0<x≤0.50.
10. The alkaline electrochemical cell of claim 8 , wherein the substituted solid particulate zinc oxide has the formula ZnO 1-w A (2w/z) or Zn(OH) 2-w A (w/z) , wherein A is at least one anion substituent, 0<w≤0.50, and z is the charge of the anion substituent.
11. The alkaline electrochemical cell of claim 8 , wherein the substituted solid particulate zinc oxide is a cation-substituted and anion-substituted mixed oxide hydroxide, and has the formula Zn 1-x Y x O 1-w-t (OH) 2w A (2t/z) , wherein Y is at least one cation substituent, wherein 0<x≤0.50, wherein A, if present, is at least one anion substituent, 0<w≤0.50, 0≤t≤0.50, and z is the charge of the anion substituent.
12. The alkaline electrochemical cell of claim 8 , wherein the cation substituent, if present, is selected from the group consisting of Mg, Ca, Bi, Ba, Al, Si, Be, Cd, Ni, Co, Sn, and Sr, and any combination thereof, and the anion substituent, if present, is selected from the group consisting of CO 3 2- and PO 4 3- , and a combination thereof.
13. The alkaline electrochemical cell of claim 2 , wherein the alkaline electrochemical cell comprises a total zinc oxide weight percent of about 3.0-8.8%.
14. The alkaline electrochemical cell of claim 2 , wherein the alkaline electrochemical cell comprises a total zinc oxide weight percent of greater than about 7.0%.
15. The alkaline electrochemical cell of claim 2 , wherein the anode comprises an electrolyte concentration percent of about 16.0-30.0%.
16. The alkaline electrochemical cell of claim 1 , wherein the full cell electrolyte concentration is about 26.0-30.0%.
17. The alkaline electrochemical cell of claim 1 , wherein the total cell saturation of zinc oxide or zinc hydroxide is at least about 40%.
18. The alkaline electrochemical cell of claim 1 , wherein the alkaline electrochemical cell has a specific capacity or runtime that is greater than that of a similar alkaline electrochemical cell which lacks the dissolved zinc oxide in the free electrolyte.
19. The alkaline electrochemical cell of claim 1 , wherein the cell is a primary cell.