Battery with electrochemical tester

• US 5,396,177 A
• Filed: 07/22/1992
• Issued: 03/07/1995
• Est. Priority Date: 09/24/1991
• Status: Expired due to Term

• Current Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Original Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Inventors: Wu, Louis L., Chi, Ignacio, Lin, Lifun, Kuo, Han C.
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US07/914,900
• Time in Patent Office: 958 Days
• Field of Search: 324/426, 324/435, 324/104, 340/636, 320/48
• US Class Current: 324/435
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 16/00 Structural combinations of different types of electrochemical generators
• CPC Class Codes: H01M 6/5044 Cells or batteries structurally combined with cell condition indicating means
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

The present invention relates to an electrochemical cell and a related state of charge indicator comprising an electrochemically generated display. The state of charge indicator comprises two electrical contacts and an electrochemically generated display connected therebetween. The display comprises an electrochemical cell that may be permanently connected to a main cell in a parallel configuration via the contacts. The condition of the main cell may thus be continuously displayed on the indicator.

Claims

1. In combination, a first electrochemical cell and a cell condition indicator wherein said first electrochemical cell comprises a casing and a positive and negative terminal and said condition indicator operates by having electrochemical activity occur therein and comprises an electrochemically stimulated display means;

said indicator having a thickness of less than about 100 mils (2.5 mm);

wherein the condition of the first cell is determined by observing a visible condition of said display means as the first cell is discharged.

2. The combination of claim 1 wherein said display means comprises a second electrochemical cell permanently electrically connected in parallel to said first cell.

3. The combination of claim 2 wherein said second cell has an open circuit voltage similar to the open circuit voltage of the first cell.

4. The combination of claim 3 wherein said second cell has an open circuit voltage (OCV) between about 80 and 120 percent of the open circuit voltage (OCV) of the first cell.

5. The combination of claim 2 wherein a resistor is added in series with at least one of the first electrochemical cell and the second electrochemical cell.

6. The combination of claim 2 wherein said second cell has an impedance of at least 100 times the impedance of the first cell.

7. The combination of claim 2 wherein said display means comprises a visible, electrochemically removable layer.

8. The combination of claim 2 wherein said display means comprises a cathode active layer electrically connected to said positive terminal, an anode active layer electrically connected to said negative terminal, an electrolyte layer located between at least a portion of said cathode and anode layers, wherein at least one of the cathode and anode layers is electrochemically removed during discharge of the first electrochemical cell to indicate the condition of said first cell.

9. The combination of claim 8 wherein said display means is positioned along a portion of said casing and said combination further comprises a label wrapped around the casing wherein a transparent portion of said label covers said display means, and said display means further comprises a color or indicia layer which is revealed when one of said cathode and anode active layers is electrochemically removed during discharge of the first electrochemical cell.

10. The combination of claim 8 wherein said cathode active layer comprises a compound selected from the group consisting of CoO₂, NiO₂ and lambda MnO₂ and said anode active layer comprises zinc.

11. The combination of claim 8 wherein said electrolyte layer comprises an electrolytic film having a conductivity of at least 1×

10^-7 ohm^-1 cm^-1.

12. The combination of claim 11 wherein said electrolytic film comprises a porous polymeric film retaining a liquid electrolyte solution within the pores of said polymeric film.

13. The combination of claim 12 wherein said polymeric film is selected from the group consisting of polyvinylidene fluoride and polyacrylonitrile.

14. The combination of claim 12 wherein said liquid electrolyte solution comprises an ionic salt dissolved therein, said ionic salt selected from the group consisting of LiCF₃ SO₃, LiClO₄, Zn(CF₃ SO₃)₂, Zn(ClO₄)₂, LiN(CF₃ SO₂)₂ and combinations thereof.

15. The combination of claim 12 wherein the electrolyte solution comprises an organic solvent selected from the group consisting of ethylene carbonate and propylene carbonate and mixtures thereof.

16. The combination of claim 11 wherein said electrolytic film comprises a polymeric film selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinylidene chloride, and polyester.

17. The combination of claim 2 wherein the cell condition indicator further comprises a barrier layer electrically insulating said anode and cathode active layers from the casing.

18. The combination of claim 2 wherein every part of the condition indicator substantially conforms to the shape of the adjacent portion of said casing.

19. The combination of claim 2 wherein said second electrochemical cell has a thickness of less than about 15 mils (0.4 mm).

20. A cell condition indicator for testing the condition of an electrochemical cell, said condition indicator being a layered structure comprising an anode active layer, a cathode active layer and an electrolyte layer contacting at least a portion of said anode and cathode active layers, said condition indicator having a thickness of less than 100 mils (2.5 mm), and said electrolyte layer comprising an electrolytic film having a conductivity of at least 1×

10^-7 ohm^-1 cm^-1.

21. The cell condition indicator of claim 20 wherein the anode active layer comprises zinc and the cathode active layer comprises a cathode active material which produces an open circuit voltage (OCV) for said condition indicator, which open circuit voltage is similar to the open circuit cell voltage of the electrochemical cell.

22. The cell condition indicator of claim 20 wherein said electrolyte layer has a thickness between about 0.05 and 0.25 mm.