REVERSIBLE ELECTRICAL CONNECTOR AND METHOD

• US 20130157104A1
• Filed: 12/14/2011
• Published: 06/20/2013
• Est. Priority Date: 12/14/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Ulicny, John C., Carlson, Blair E., Xie, Tao
• Granted Patent: US 9,525,194 B2
• Time in Patent Office: Days
• US Class Current: 429/121
• CPC Class Codes: H01M 10/54 Reclaiming serviceable parts of waste accumulators
• CPC Class Codes: H01M 50/505 comprising a single busbar
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02W 30/84 Recycling of batteries or fuel cells
• CPC Class Codes: Y10T 156/1043 Subsequent to assembly

Abstract

A method of reversibly connecting two substrates includes positioning an electrically conductive adhesive connector including a shape memory polymer (SMP) between the substrates, heating the connector to a temperature higher than the SMP transition temperature, applying a load and cooling the connector below the transition temperature to transform the connector to a conforming shape to form an adhesive bond attaching the substrates and providing an electrical connection therebetween. The method may include disconnecting the connector from the substrates by heating the connector above the SMP transition temperature, which may disrupt the electrical connection between the substrates. The connector may be a battery tab connector configured to connect a battery cell to another battery cell or a terminal. The connector may be releasable from the battery tab such that the battery tab is reusable after removal of the connector. The connector may be multi-layer and generally arcuate in a permanent shape.

Claims

1. A method comprising:

providing an electrically conductive adhesive connector including a shape memory polymer having a glass transition temperature;

providing a first substrate and a second substrate, wherein the first substrate and the second substrate are electrically conductive;

positioning the connector adjacent to the first substrate and the second substrate;

heating the connector to a temperature higher than the glass transition temperature of the shape memory polymer;

applying a load on the connector to transform the connector to a conforming shape while cooling the connector to a temperature lower than the glass transition temperature;

wherein the connector in the conforming shape;

forms an adhesive bond between the connector and the first and second substrates to operatively attach the first and second substrates; and

provides an electrical connection between the first and second substrates.

2. The method of claim 1, wherein the first substrate is a first battery tab, and the second substrate is one of a second battery tab and a battery terminal.

3. The method of claim 1, wherein:

the conforming shape is a temporary shape of the shape memory polymer of the connector; and

the shape memory polymer in a permanent shape defines a generally arcuate shape of the connector.

4. The method of claim 1, further comprising:

disconnecting the connector from the first and second substrate by heating the connector above the glass transition temperature of the shape memory polymer;

wherein disconnecting the connector disrupts the electrical connection between the first and second substrate.

5. The method of claim 4, wherein the glass transition temperature corresponds to a predetermined temperature limit.

6. The method of claim 4, wherein disconnecting the connector includes progressively peeling the connector from the first substrate and progressively peeling the connector from the second substrate.

7. The method of claim 4, further comprising:

reconnecting the connector to the first and second substrate by;

reheating the connector to a temperature higher than the glass transition temperature of the shape memory polymer; and

reapplying a load on the connector to transform the connector to a conforming shape while cooling the connector to a temperature lower than the glass transition temperature.

8. The method of claim 4, further comprising:

detaching the connector from the first and second substrate, wherein at least one of the connector, the first substrate, and the second substrate are reusable after the connector is detached.

9. The method of claim 1, wherein:

the connector is configured as a multi-layer connector including a first adhesive layer, a second adhesive layer, and a third layer between the first and second layers;

the third layer includes the shape memory polymer;

the first adhesive layer, the second adhesive layer, and the third layer are electrically conductive;

the connector is positioned with the first adhesive layer adjacent to the first substrate and the second adhesive layer adjacent to the second substrate.

10. The method of claim 9, wherein each of the first adhesive layer and the second adhesive layer includes a dry adhesive.

11. The method of claim 9, wherein:

the connector includes a fourth layer between the second layer and the third layer;

the fourth layer includes the shape memory polymer;

when the shape memory polymer is in a permanent shape, the third and fourth layers are each configured as a generally arcuate shape and arranged to define a cavity therebetween; and

when the shape memory polymer is in a temporary shape, the third and fourth layers are configured in a conforming shape with the cavity substantially eliminated.

12. The method of claim 11, further comprising:

heating the connector above the glass transition temperature of the shape memory polymer to disconnect the connector;

wherein disconnecting the connector includes recovering the generally arcuate shape of the third and fourth layers and reopening the cavity; and

discontinuing the electrical connection between the first and second substrate.

13. A connector comprising:

a first layer configured as an adhesive layer;

a second layer configured as an adhesive layer;

a third layer between the first and second adhesive layers, wherein the third layer includes a shape memory polymer having a glass transition temperature; and

wherein;

each of the first, second, and third layers is electrically conductive;

the connector in a permanent shape defined by the shape memory polymer includes a generally arcuate shape;

the connector is transformable into a temporary shape configured to substantially conform to a first substrate and a second substrate to operatively attach the first and second substrates and provide an electrically conductive path between the first substrate and the second substrate; and

the connector is releasable from the first and second substrates by heating the connector in the temporary shape above the glass transition temperature to detach the connector from the first and second substrates and disrupt the electrically conductive path between the first substrate and the second substrate.

14. The connector of claim 13, further comprising:

a fourth layer including the shape memory polymer and defined by a generally arcuate shape when the shape memory polymer is in a permanent shape;

wherein;

the fourth layer is electrically conductive;

the fourth layer is adjacent to the third layer and one of the first and second adhesive layers;

the third and fourth layers are arranged to define an opening therebetween when the connector is in the permanent shape; and

the opening is substantially eliminated when the connector is in the temporary shape.

15. The connector of claim 13, wherein the connector is configured to exert a detaching force when transforming from the temporary shape to the permanent shape sufficient to progressively peel the connector from the first substrate and the second substrate.

16. The connector of claim 13, wherein:

the connector is configured as a releasable battery tab connector;

the first substrate is defined by a battery tab of a battery cell;

the second substrate is defined by one of a second battery tab of a second battery cell, and a battery terminal; and

the connector is removable after release from the first and the second substrates such that the first battery cell and the one of the second battery cell and the battery terminal are reusable.

17. The connector of claim 13, wherein the connector is configured as a limit switch activated by heating the connector above a temperature limit corresponding to the glass transition temperature.

18. A battery pack comprising:

a first battery cell defining a first battery tab;

a second battery cell defining a second battery tab;

a reversible adhesive electrically conductive connector including a shape memory polymer;

wherein;

the connector is positioned between the first battery tab and the second battery tab;

the shape memory polymer of the connector in a permanent shape defines a generally curved shape;

the connector is transformable from the permanent shape to a temporary shape generally conforming to the first battery tab and the second battery tab by heating the connector to a temperature higher than a transition temperature of the shape memory polymer, and applying a load on the connector to transform the connector to the conforming shape while cooling the connector to a temperature lower than the transition temperature;

in the conforming shape, the connector forms an adhesive bond between the connector and the first and second substrates to operatively attach the first and second substrates and provide an electrical connection between the first and second substrates;

the connector is releasable from the first and second battery tabs by heating the connector in the temporary shape above the glass transition temperature to recover the permanent shape of the connector; and

the first and the second battery cells are recyclable after the first and second battery tabs are released from the connector.

19. The battery pack of claim 18, wherein the connector is configured as a multi-layer connector including:

a first adhesive layer;

a second adhesive layer;

a third layer between the first and second adhesive layers, wherein the third layer includes the shape memory polymer; and

wherein;

each of the first, second, and third layers is electrically conductive; and

the connector is configured to exert a detaching force when recovering the permanent shape sufficient to progressively peel the first adhesive layer from the first battery tab and the second adhesive layer from the second battery tab.

20. The battery pack of claim 18, wherein the connector is configured to disrupt the electrical connection between the first battery tab and the second battery tab when the connector is heated above a temperature limit of the battery pack corresponding to the glass transition temperature.