Electrochemical cell
View Patent ↗A cylindrical alkaline electrochemical cell is disclosed that includes a gel free anode. The anode includes a free flowing zinc powder with a preassembly tap density between 1.6 g/cc and 2.9 g/cc. In one embodiment, zinc powder with the desired tap density may be obtained by mixing zinc agglomerates with zinc flakes.
1. An electrochemical cell, comprising:
a) a container;
b) a first electrode disposed in said container, said first electrode contacting said container and defining a cavity therein;
c) a separator lining said cavity; and
d) a gel free second electrode disposed in said separator lined cavity, said second electrode comprising an agglomerated zinc powder containing less than 50 ppm of mercury and having a preassembly tap density greater than 1.6 g/cc and less than 2.9 g/cc.
2. The electrochemical cell, as defined in claim 1 , wherein the second electrode further comprises zinc flakes.
3. The electrochemical cell, as defined in claim 2 , wherein the zinc powder's preassembly tap density is greater than 1.8 g/cc and less than 2.2 g/cc.
4. The electrochemical cell, as defined in claim 1 , wherein the zinc powder is alloyed with at least one selected from the group consisting of: bismuth, indium and aluminum.
5. The electrochemical cell, as defined in claim 4 , wherein the zinc powder's preassembly tap density is greater than 1.8 g/cc and less than 2.2 g/cc.
6. The electrochemical cell, as defined in claim 4 , wherein the second electrode further comprises zinc flakes.
7. An electrochemical cell comprising:
a) a container;
b) a first electrode disposed in said container, said first electrode contacting said container and defining a cavity therein;
c) a separator lining said cavity;
d) a gel free second electrode disposed in said separator lined cavity, said second electrode comprising an electrochemically active material and less than 50 ppm of mercury, said electrochemically active material consisting essentially of a mixture of zinc powders, said mixture of zinc powders comprising a first zinc powder, a second zinc powder and an optional alloy material, said first zinc powder having a preassembly tap density less than 2.0 g/cc and second zinc powder having a preassembly tap density greater than 2.0 g/cc; and
e) wherein the mixture of zinc powders includes agglomerated particles.
8. The electrochemical cell, as defined in claim 7 , wherein said second zinc powder has a tap density greater than 3.0 g/cc.
9. The electrochemical cell, as defined in claim 7 , wherein said second zinc powder has a tap density greater than 3.2 g/cc.
10. The electrochemical cell, as defined in claim 7 , wherein said second zinc powder has a tap density greater than 3.5 g/cc.
11. The electrochemical cell, as defined in claim 7 , wherein said first zinc powder has a tap density less than 1.7 g/cc.
12. The electrochemical cell, as defined in claim 7 , wherein said first zinc powder has a tap density greater than 1.1 g/cc.
13. The electrochemical cell, as defined in claim 7 , wherein said mixture of zinc powders also includes zinc flakes.
14. The electrochemical cell, as defined in claim 7 , wherein said first zinc powder consists essentially of zinc flakes and said second zinc powder consists essentially of zinc agglomerates and particles associated with the zinc agglomerates.
15. The electrochemical cell, as defined in claim 7 , wherein said first zinc powder is at least 5 weight percent of the total weight of said composition of zinc powders.
16. The electrochemical cell, as defined in claim 7 , wherein said first portion of zinc powder is at least 10 weight percent of the total weight of said composition of zinc powders.
17. The electrochemical cell, as defined in claim 7 , wherein said first portion of zinc powder is at least 15 weight percent of the total weight of said composition of zinc powders.
18. The electrochemical cell, as defined in claim 7 , wherein said first portion of zinc powder is at least 20 weight percent of the total weight of said composition of zinc powders.
19. A process for manufacturing an electrochemical cell, comprising:
a. providing a container comprising a first electrode and a separator, said separator contacting said first electrode and defining a cavity therein;
b. providing a second electrode comprising an electrochemically active material with less than 50 ppm of mercury, said electrochemically active material consisting essentially of a zinc powder having agglomerated particles and a preassembly tap density greater than 1.6 g/cc and less than 2.9 g/cc and said second electrode not containing any gelling agents;
c. disposing said second electrode into said cavity; and
d. securing a sealing member to said container.
20. The process of claim 19 , further comprising the step of forming the zinc powder by mixing a first zinc powder having a preassembly tap density less than 2.0 g/cc and a second zinc powder having a preassembly tap density greater than 2.0 g/cc.
21. The process of claim 20 , wherein said second zinc powder has a tap density greater than 3.0 g/cc.
22. The process of claim 20 , wherein said second zinc powder has a tap density greater than 3.2 g/cc.
23. The process of claim 20 , wherein said second zinc powder has a tap density greater than 3.5 g/cc.
24. The process of claim 20 , wherein said first zinc powder has a tap density less than 1.7 g/cc.
25. The process of claim 20 , wherein said first portion of zinc powder has a tap density greater than 1.1 g/cc.
26. The process of claim 19 , wherein the zinc powder is alloyed with at least one selected from the group consisting of: bismuth, indium and aluminum.
27. The process of claim 19 , wherein said zinc powder is disposed into said cavity prior to disposing the electrolyte into said cavity.
28. The process of claim 19 , wherein a portion of said electrolyte is disposed into said cavity before said zinc powder is disposed into said cavity.
29. The process of claim 19 , wherein said zinc powder and said electrolyte are simultaneously disposed into said cavity.
30. The process of claim 19 , wherein said zinc powder and electrolyte are mixed with one another and then disposed into said cavity.