Electrochemical cell label with integrated tester

• US 5,607,790 A
• Filed: 06/01/1995
• Issued: 03/04/1997
• Est. Priority Date: 09/29/1994
• Status: Expired due to Term

• Current Assignee: Gillette Company (The Procter & Gamble Company)
• Original Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Inventors: Ferguson, Scott, Hughen, John, Garris, Michael
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US08/456,428
• Time in Patent Office: 642 Days
• Field of Search: 429/91-93
• US Class Current: 429/93
• CPC Class Codes: H01M 10/488 Cells or batteries combined with indicating means for external visualization of the condition, e.g. by change of colour or of light density
• CPC Class Codes: H01M 6/505 Cells combined with indicating means for external visualization of the condition, e.g. by change of colour or of light intensity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10T 29/49115 including coating or impregnating

Abstract

A label for an electrochemical cell with a condition tester for the cell integrated with the label to form a label/tester composite is disclosed. The label/tester composite has a thermochromic material in thermal contact with an electrically conductive material. A substructure containing a cured conductive material and preferably also a thermochromic material is formed on a releasable web and transferred from the releasable web to the inside surface of the heat shrinkable base film. A partition coating may be applied over the transferred conductive material. Preferably, a sheet of paper or plastic film having a large window opening therein for entrapping air is applied over the partition coating and aligned over the heat generating portion of the conductive material. The label/tester composite is applied to the cell housing with the insulating paper or plastic film with window opening against the cell housing. The tester may be activated by depressing one or two regions on its surface thereby connecting the conductive material to the terminals of the cell, whereupon the conductive material becomes heated causing a change in appearance of the thermochromic material to indicate the condition of the cell.

Claims

1. In combination, an electrochemical cell and a label/tester composite;

said cell comprising positive and negative terminals and a metal housing;

said label/tester composite being attached to the cell housing, a portion of said housing forming one of said terminals;

said composite including a film having a thermochromic material disposed thereon, an electrically conductive material in thermal contact with the thermochromic material, means for thermally insulating said conductive material from the cell housing, wherein a portion of said conductive material is capable of generating sufficient heat when electrically connected to the terminals of said cell when undischarged to cause a change in appearance in the thermochromic material in thermal contact therewith and wherein said means comprises an opening in a surface of a substantially electrically nonconductive material so that the perimeter of said opening is defined by said nonconductive material, wherein said opening is of sufficient size to equal at least 40% of the surface area of one side of said heat generating portion of said conductive material.

2. The combination of claim 1 wherein said opening is an elongated slot having a smaller width than length and aligned in relation to the cell so that its width is substantially in the circumferential direction of the cell housing.

3. The combination of claim 1 wherein said electrically nonconductive material is of sufficient thickness to provide thermal insulation from air trapped in said opening.

4. The combination of claim 1 wherein the cell is cylindrical and the thickness of said electrically nonconductive material and the width of said opening are predetermined so that no portion of the label/tester composite exclusive of said electrically nonconductive material contacts the cell housing through said opening when the composite is attached to the cell.

5. The combination of claim 1 wherein said electrically nonconductive material has a volume resistivity greater than about 2.7×

10⁶ ohm-cm and a thermal conductivity less than about 10 watt m^-1 K^-1.

6. The combination of claim 1 wherein the thickness of said electrically nonconductive material having said opening therein is between about 2 mils and 12 mils (0.05 mm and 0.3 mm).

7. The combination of claim 5 wherein said opening equals an area of at least 60% of the surface area of one side of said heat generating portion of said conductive material.

8. The combination of claim 5 wherein said electrically nonconductive material is selected from the group consisting of paper, plastic film, polymeric foam and any combination thereof.

9. The combination of claim 5 wherein said electrically nonconductive material comprises paper.

10. The combination of claim 1 further comprising a partition coating between said conductive material and said electrically nonconductive material, said partition coating having at least one cavity extending through the thickness thereof, wherein a portion of the conductive material is positioned over said cavity;

the tester being activatable by applying manual pressure over the conductive portion over said cavity thereby causing it to be pushed therethrough and electrically contact a cell terminal.

11. The combination of claim 10 wherein a portion of said partition coating covers an opening in said electrically nonconductive material and wherein said portion covering said opening is a continuous coating having no gaps in its surface.

12. The combination of claim 10 wherein a portion of said partition coating covers an opening in said electrically nonconductive material and wherein said portion covering said opening is a coating having at least one gap in its surface.

13. The combination of claim 1 wherein the metal housing of said cell has a cylindrical wall with first and second shoulders at respective ends thereof, and wherein said label/tester composite comprises means for permitting at least one end of the composite to be heat shrunk evenly over one of said cell shoulders.

14. The combination of claim 13 wherein said means for said at least one end of the composite to be heat shrunk evenly comprises at least two fingers protruding from said end of the conductive material.

15. The combination of claim 1 wherein said film having the thermochromic material disposed thereon is a heat shrinkable film selected from the group consisting of unplasticized polyvinylchloride and polypropylene.

16. The combination of claim 1 wherein said film is a heat shrinkable film printed with graphics on one side thereof and wherein said film has pressure sensitive adhesive on the same side thereof as the graphics, and said composite is attached to the cell by wrapping it around the cell housing so that the adhesive contacts the housing.

17. The combination of claim 1 wherein the label/tester composite has a thickness of less than 100 mils (2.5 mm).

18. The combination of claim 10 wherein an opening in said electrically nonconductive material has a greater area than the largest of any said cavity in said partition coating through which the tester is activatable.

19. The combination of claim 10 wherein at least one of said cavities through which the tester is activatable has a depth between about 0.1 mil (0.0025 mm) and 2.0 mils (0.05 mm).

20. The combination of claim 10 wherein said cavity and said conductive portion have a combined depth of between about 0.35 mil (0.009 mm) and 3.0 mil (0.075 mm).

21. The combination of claim 11 wherein the continuous portion of said partition coating covering said opening has a thickness between about 0.1 mil (0.0025 mm) and 7 mil (0.18 mm).

22. A label/tester composite for application to an electrochemical cell having a housing and a pair of terminals, said housing having a cylindrical wall with first and second shoulders at respective ends thereof, said label/tester composite comprising a base film and an adhesive coating over one side of the base film, a thermochromic material, an electrically conductive material in thermal contact with the thermochromic material, and separation means for maintaining the conductive material spaced from the housing when the composite is applied thereto, wherein the thermochromic material, the electrically conductive material, and said separation means are on the same side of the base film as the adhesive coating, said separation means comprising a material at least substantially electrically nonconductive and having an opening therein, said conductive material having at least two spaced apart fingers protruding from an end thereof whereby that end of the label/tester composite can be evenly heat shrunk over a shoulder of the cell.

23. The combination of claim 22 wherein a portion of said conductive material is capable of generating sufficient heat when electrically connected to the terminals of an undischarged cell to cause a change in appearance in the thermochromic material in thermal contact therewith, wherein said separation means comprising said electrically nonconductive material has an opening therein of sufficient size to equal at least 40% of the surface area of one side of said heat generating portion of said conductive material, said opening providing thermal insulation from air entrapped therein when said composite is applied to the cell housing.

24. The combination of claim 23 wherein said electrically nonconductive material is selected from the group consisting of paper, plastic film, polymeric foam and any combination thereof.

25. The combination of claim 23 wherein the depth of an opening in said electrically nonconductive material is between about 2 mils and 12 mils (0.05 and 0.3 mm).

26. The combination of claim 23 wherein an opening in said electrically nonconductive material covers an area of at least 60% of the surface area of one side of said heat generating portion of said conductive material.

27. The combination of claim 22 further comprising a partition coating between said conductive material and said electrically nonconductive material, said partition coating having at least one cavity extending through the thickness thereof, wherein a portion of the conductive material is positioned over said cavity;

the tester being activatable by applying manual pressure over the conductive portion over said cavity thereby causing it to be pushed therethrough and electrically contact a cell terminal.

28. The combination of claim 27 wherein an opening in said electrically nonconductive material has a greater area than the surface area of the largest cavity through which the conductive portion may be pushed to electrically contact a cell terminal.

29. The combination of claim 27 wherein a portion of said partition coating covers an opening in said electrically nonconductive material and wherein said portion of the partition coating covering said opening is a continuous coating having no gaps in its surface.

30. The combination of claim 27 wherein said electrically nonconductive material is bonded to said partition coating with an ultraviolet light (U.V.) curable adhesive.

31. In a label/tester composite for application to an electrochemical cell having a housing and a pair of terminals, said label/tester composite of the type comprising a base film and an adhesive coating over one side of the base film, a thermochromic material, an electrically conductive material in thermal contact with the thermochromic material, and separation means for maintaining the conductive material spaced from the housing when the composite is applied thereto, wherein the thermochromic material, the electrically conductive material, and said separation means are on the same side of the base film as the adhesive coating, wherein a portion of said conductive material is capable of generating sufficient heat when electrically connected to the terminals of an undischarged cell to cause a change in appearance in the thermochromic material in thermal contact therewith, the improvement comprising said separation means comprising a substantially electrically nonconductive material having an opening through a surface thereof, said opening being of sufficient size to equal at least 40% of the surface area of one side of said heat generating portion of said conductive material, said opening providing thermal insulation from air entrapped therein when said composite is applied to the cell housing.

32. The combination of claim 31 wherein said electrically nonconductive material has an opening therein of sufficient size to cover at least 60% of the surface area of one side of said heat generating portion of said conductive material, said opening providing thermal insulation from air entrapped therein when said composite is applied to the cell housing.

33. The combination of claim 31 wherein said electrically conductive material comprises a paper sheet having an opening therein equaling an area of at least 80% of the surface area of one side of said heat generating portion of said conductive material.