Electrochemical cell label with integrated tester

• US 5,614,333 A
• Filed: 02/08/1996
• Issued: 03/25/1997
• 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:
  US08/598,455
• Time in Patent Office: 411 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 50/107 having curved cross-section, e.g. round or elliptic H01M50/103, H01M50/109, H01M50/11 take precedence
• CPC Class Codes: H01M 50/119 Metals
• 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

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, a portion of said metal housing forming one of said terminals;

said metal housing having a cylindrical wall with first and second shoulders at respective ends thereof;

said label/tester composite being attached to the cell housing;

said composite including a film around said housing, said film having a thermochromic material disposed on the side of the film facing said housing, an electrically conductive material in thermal contact with the thermochromic material, said conductive material being between said thermochromic material and said housing, and means for thermally insulating said conductive material from the cell housing, wherein said insulating means comprises a substantially electrically nonconductive material, and wherein said label/tester composite comprises means for enabling at least one end of the composite to be heat shrunk evenly over one of said cell shoulders, said means for at least one end of the composite to be heat shrunk evenly over one of said shoulders comprises at least two conductive fingers protruding from said conductive material, said composite further comprising a partition coating between said conductive material and said electrically nonconductive material, wherein a portion of said partition coating forms a plurality of protruding ribs, wherein said conductive fingers rest on said ribs, wherein said ribs define therebetween a plurality of cavities through which said conductive fingers may be manually pushed in order to electrically contact said conductive fingers with one of said terminals.

2. The combination of claim 1 wherein said electrically nonconductive material has an opening therethrough through which a portion of the conductive material may be manually pushed to electrically contact said portion of the conductive material with the cell housing.

3. The combination of claim 2 wherein the tester is activatable by exerting manual pressure over both said conductive fingers resting on said ribs and said portion of the conductive material over said opening and wherein said tester is deactivated when said manual pressure is removed.

4. 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 around said housing, said film having a thermochromic material disposed thereon, an electrically conductive material in thermal contact with the thermochromic material, said conductive material being between said thermochromic material and said 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 said thermochromic materials said composite further comprising means for thermally insulating said conductive material from the cell housing, said means comprising a first opening in a substantially electrically nonconductive material, and said first 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 electrically nonconductive material having a second opening therethrough wherein said second opening is spaced apart from said first opening whereby the tester may be activated by pushing a portion of the conductive material through said second opening to electrically contact said portion of the conductive material with a portion of the cell housing.

5. The combination of claim 4 wherein said first opening in said electrically nonconductive material 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.

6. The combination of claim 4 wherein said electrically nonconductive material is of sufficient thickness to provide thermal insulation from air trapped in said first opening.

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

8. The combination of claim 4 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.

9. The combination of claim 8 wherein the thickness of said electrically nonconductive material is between about 2 mils and 12 mils (0.05 mm and 0.3 mm).

10. The combination of claim 8 wherein said first opening in the 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.

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

12. The combination of claim 8 wherein said electrically nonconductive material comprises paper.

13. The combination of claim 4 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 enabling 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 conductive fingers protruding from said conductive material.

15. The combination of claim 14 further comprising a partition coating between said conductive material and said electrically nonconductive material.

16. The combination of claim 15 wherein a portion of said partition coating covers said first opening in said electrically nonconductive material and wherein said portion of the partition coating covering said first opening is a continuous coating having no gaps in its surface.

17. The combination of claim 15 wherein a portion of said partition coating forms a plurality of protruding ribs, wherein said conductive fingers rest on said ribs, wherein said ribs define therebetween a plurality of cavities through which said conductive fingers may be pushed.

18. The combination of claim 4 wherein said film having the thermochromic material disposed thereon is a heat shrinkable film selected from the group consisting of unplasticized polyvinylchloride and polypropylene.

19. The combination of claim 4 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.

20. The combination of claim 4 wherein the label/tester composite has a thickness of less than 100 mils (2.5 mm).

21. The combination of claim 4 wherein said second opening in the electrically nonconductive material has a diameter between about 1.6 and 2.4 mm.

22. The combination of claim 17 wherein at least one of said cavities defined by said ribs has a depth of between about 0.1 mil (0.0025 mm) and 2.0 mil (0.05 mm).