Primary lithium electrochemical cell
View Patent ↗A primary electrochemical cell includes a cathode including lambda-manganese dioxide (λ-MnO 2 ), an anode including lithium or a lithium alloy, a separator interposed between the cathode and the anode, and a non-aqueous electrolyte contacting the anode and the cathode.
1. A method of manufacturing an electrochemical cell, the method comprising:
selecting a lambda manganese oxide that, when incorporated into a positive electrode of a cell, can provide the cell with a specific discharge capacity at a nominal discharge rate of 1 mA/cm 2 to a 3V cutoff of greater than 130 mAh/g;
incorporating the lambda manganese oxide into a positive electrode; and
forming a cell including the positive electrode and a lithium negative electrode,
wherein the cell has a closed circuit voltage of about 4V and a specific discharge capacity at a nominal discharge rate of 1 mA/cm 2 to a 3V cutoff of greater than 130 mAh/g.
2. The method of claim 1 , wherein selecting the lambda manganese oxide includes preparing lambda-manganese dioxide by a method comprising:
contacting water with a compound of the formula Li 1 +× Mn 2−× O 4 , wherein x is from −0.02 to +0.02;
adding an acid to the water and compound until the water has a pH of 1 or less;
separating a solid from the water and acid; and
drying the solid at a temperature of 120° C. or below to obtain the lambda-manganese dioxide.
3. The method of claim 2 , wherein the compound has a BET surface area of between 1 and 10 m 2 /g.
4. The method of claim 2 , wherein the compound has a spinel-type crystal structure.
5. The method of claim 2 , wherein the solid is dried at a temperature between 30° C. and 90° C.
6. The method of claim 2 , wherein the solid is dried at a temperature between 50° C. and 70° C.
7. The method of claim 2 , wherein x is from −0.005 to +0.005.
8. The method of claim 2 , wherein contacting water and the compound includes forming a slurry.
9. The method of claim 8 , wherein the slurry is maintained at a temperature below 50° C.
10. The method of claim 8 , wherein the temperature of the slurry is held substantially constant during the addition of acid.
11. The method of claim 2 , wherein the acid comprises sulfuric acid, nitric acid, perchloric acid, hydrochloric acid, toluenesulfonic acid or trifluoromethylsulfonic acid.
12. The method of claim 2 , wherein the pH is 0.7 or less.
13. The method of claim 2 , wherein the acid has a concentration of between 1 and 8 molar.
14. The method of claim 2 , further comprising washing the solid separated from the liquid phase with water until the washings have a pH of between 6 and 7.
15. The method of claim 1 , wherein the cell comprises a primary cell.
16. The method of claim 1 , wherein the cell has a specific discharge capacity at a nominal discharge rate of 1 mA/cm 2 to a 3V cutoff of greater than 135 mAh/g.
17. The method of claim 1 , wherein the cell has a specific discharge capacity at a nominal discharge rate of 1 mA/cm 2 to a 3V cutoff of 140 mAh/g or greater.
18. The method of claim 1 , wherein the lambda-manganese oxide has a BET surface area of greater than 4 m 2 /g.
19. The method of claim 1 , wherein the lambda-manganese oxide has a BET surface area of greater than 8 m 2 /g.
20. The method of claim 1 , wherein the lambda-manganese oxide has a total pore volume of from 0.05 to 0.15 cubic centimeters per gram.