Alkaline cells having high capacity
View Patent ↗Aspects of the present invention provide a high capacity electrochemical cell having an anode, a cathode, and a separator disposed between the anode and cathode. The cathode includes a mixture having a first component, a second component and a third component. The first component includes a first element, the second component includes a second element, and the third component includes the first element and the second element. The mixture can, for instance, be a mixed metal oxide. The separator is configured to provide suitable ionic transport between the anode and the cathode.
1. An electrochemical cell comprising:
an anode;
a cathode comprising a cathode active material, the cathode active material comprising a mixture, the mixture comprising a first metal oxide component, a second metal oxide component and a third metal oxide component, wherein the first, second and third metal oxide components are different, and further wherein the first metal oxide component consists of a first metallic element and oxygen, the second metal oxide component consists of a second metallic element different from the first metallic element and oxygen, and the third metal oxide component is a compound comprising the first metallic element manganese and the second metallic element; and
a separator disposed between the anode and the cathode wherein the cathode active material displays a continuous discharge profile that is substantially at least 1.0V for the first 20% of cell discharge when discharged at a discharge rate of 30 mA in a half-cell test.
2. The electrochemical cell as recited in claim 1 , wherein the second element is copper.
3. The electrochemical cell as recited in claim 2 , wherein the copper content is greater than about 0.5% by weight of the mixture.
4. The electrochemical cell as recited in claim 1 , wherein the third metal oxide component further comprises a third metallic element.
5. The electrochemical cell as recited in claim 1 , wherein the third metal oxide component is a compound identified by M x Cu y O z , and:
M is a metallic element Mn capable of producing mixed metal oxide compounds or complexes, and x≦20, y≦20, and z≦100.
6. The electrochemical cell as recited in claim 1 , wherein the ratio of the first metal oxide component to the second metal oxide component is greater than about 1:100.
7. The electrochemical cell as recited in claim 6 , wherein the ratio of the first metal oxide component to the second metal oxide component is greater than about 1:20.
8. The electrochemical cell as recited in claim 5 , wherein M x Cu y O z has the formula where x is substantially equal to 3−y and z=4.
9. The electrochemical cell as recited in claim 5 , wherein M x Cu y O z has the formula where x is substantially equal to 2−y and z=2.
10. The electrochemical cell as recited in claim 5 , wherein M x Cu y O z has a spinel type of crystal structure.
11. The electrochemical cell as recited in claim 5 , wherein M x Cu y O z has a tenorite type of crystal structure.
12. The electrochemical cell as recited in claim 5 , wherein the third metal oxide component further comprises an additional metal A, the third component having the formula A w M x Cu y O z , wherein w≦20.
13. The electrochemical cell as recited in claim 12 , wherein the additional metal is selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Mg, Sr, Ni and Ba.
14. The electrochemical cell as recited in claim 5 , wherein the third metal oxide component is amorphous.
15. The electrochemical cell as recited in claim 5 , wherein the third metal oxide component is at least partially crystalline.
16. The electrochemical cell as recited in claim 1 , wherein the first metal oxide component consisting of a manganese oxide.
17. The electrochemical cell as recited in claim 16 , wherein the manganese oxide consisting of manganese dioxide.
18. The electrochemical cell as recited in claim 1 , wherein the second component consisting of an oxide of copper.
19. The electrochemical cell as recited in claim 18 , wherein the oxide of copper comprises cupric oxide.
20. The electrochemical cell as recited in claim 1 , wherein the cathode achieves a discharge capacity of at least 220 mAh/g at 5 mA constant current to a 1.0V end point in a half-cell test.
21. The electrochemical cell as recited in claim 1 , wherein the cathode achieves a discharge capacity of at least 180 mAh/g at 30 mA constant current to a 1.0V end point in a half-cell test.
22. The electrochemical cell as recited in claim 1 , wherein the separator comprises a film, the separator being configured to effectively limit the migration of anode fouling soluble species.
23. The electrochemical cell as recited in claim 22 , wherein substantially all fluid communication between the anode and the cathode occurs through the separator.
24. The electrochemical cell as recited in claim 1 , wherein the mixture comprising the cathode active material has a BET surface area between 1 m 2 /g and 200 m 2 /g.
25. The electrochemical cell as recited in claim 1 , wherein the cathode further comprises a conductive additive present in an amount between 3% and 8.5% by weight of the cathode.
26. The electrochemical cell as recited in claim 25 , wherein the conductive additive is selected from the group consisting of a graphitic carbon and a carbon black.
27. The electrochemical cell as recited in claim 26 , wherein the graphitic carbon comprises at least one of natural, synthetic or expanded graphite.
28. The electrochemical cell as recited in claim 26 , wherein the carbon black comprises an acetylene black present in an amount within a range having a lower end of 0.2% and an upper end of 2% by weight relative to the total cathode.
29. The electrochemical cell as recited in claim 1 , wherein the mixture has a particle size distribution between 0.1 microns and 200 microns.
30. The electrochemical cell as recited in claim 1 , wherein the mixture is further combined with at least one of a copper oxide, a manganese oxide, a silver oxide, and a nickel oxide to produce an active material combination.
31. The electrochemical cell as recited in claim 30 , wherein the manganese oxide is selected from the group consisting of EMD, NMD, and CMD.
32. The electrochemical cell as recited in claim 30 , wherein the copper oxide is cupric oxide.
33. The electrochemical cell as recited in claim 30 , wherein the mixture is present in the combination in a range having a lower end of 1% and an upper end of 99%, by weight, of the combination.
34. The electrochemical cell as recited in claim 33 , wherein the lower end is 1% and the upper end is 70%.
35. The electrochemical cell as recited in claim 25 , wherein the additive has a particle size substantially similar to the particle size of the mixture.
36. The electrochemical cell as recited in claim 31 , further comprising an alkaline electrolyte.
37. The electrochemical cell of claim 36 , wherein the alkaline electrolyte is present in an amount such that the cell includes a water/MnO 2 molar ratio greater than about 1.3.
38. The electrochemical cell as recited in claim 1 , wherein the cathode has a density in a range defined at its lower end by 3.0 gm/cc and its upper end by 4.2 gm/cc.
39. The electrochemical cell as recited in claim 1 , wherein the anode capacity to cell internal volume ratio is between 0.55 Ah/cc and 0.9 Ah/cc.
40. An electrochemical cell comprising:
an anode;
a cathode comprising a cathode active material, the cathode active material comprising a mixture of three different metal oxide components, wherein the components are selected from an oxide consisting of manganese and oxygen, an oxide consisting of copper and oxygen, and a component identified by the formula Mn x Cu y O z ; and
a separator disposed between the anode and the cathode
wherein (i) y has a positive value that is less than 3, x=3−y, and z=4, (ii) y has a positive value that is less than 2, x=2−y, and z=2, or (iii) 1≦x≦5,1≦y≦5, and 1≦z≦20; and
wherein the cathode active material displays a continuous discharge profile that is substantially at least 1.0V for the first 20% of cell discharge when discharged at a discharge rate of 30 mA in a half-cell test.
41. The electrochemical cell as recited in claim 40 , wherein the mixture is combined with at least one of a manganese oxide, a silver oxide, a copper oxide and a nickel oxide to produce an active material combination.
42. The electrochemical cell as recited in claim 41 , wherein the manganese oxide is selected from the group consisting of EMD, NMD, and CMD.
43. The electrochemical cell as recited in claim 42 , wherein the mixture is present in the active material combination in an amount ranging between 1% and 99%, by weight, of the active material combination.
44. The electrochemical cell as recited in claim 42 , wherein the mixture is present in the active material combination in an amount ranging between 1% and 70%.
45. The electrochemical cell as recited in claim 42 , the cell further comprises an alkaline electrolyte.
46. The electrochemical cell of claim 45 , wherein the alkaline electrolyte is present in an amount such that the cell includes a water/MnO 2 molar ratio of at least 1.4.