Current interrupt apparatus particularly adapted for use with prismatic electrochemical cells

• US 6,204,635 B1
• Filed: 05/13/1999
• Issued: 03/20/2001
• Est. Priority Date: 05/22/1998
• Status: Expired due to Fees

• Current Assignee: Sensata Technologies Massachusetts Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Sullivan, Steven K.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/311,489
• Time in Patent Office: 677 Days
• Field of Search: 320/134, 320/136, 320/147, 320/FOR.142, 320/FOR.145, 429/7, 429/53, 429/54, 429/55, 429/56, 429/61, 429/62, 429/64, 429/72, 429/82, 429/89, 429/167, 429/170, 429/172
• US Class Current: 320/134
• CPC Class Codes: H01M 50/169 by welding, brazing or soldering
• CPC Class Codes: H01M 50/342 Non-re-sealable arrangements
• CPC Class Codes: H01M 50/3425 in the form of rupturable membranes or weakened parts, e.g. pierced with the aid of a sharp member
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A pressure actuated current interrupt device particularly useful for prismatic electrochemical cells has a cup-shaped member (12, 12′, 12″, 12′″, 12^IV, 12^V, 12^VI) mounted on the cover of the cell and arranged to protrude into the interior of the cell. The cup-shaped member can be formed either as a separate member or as a portion of a layer of a composite cover. The cup-shaped member has a side wall (12b) in which stress is created by pressure generated in the cell which acts on the generally flat end wall (12a) of the cup-shaped member. A selected amount of pressure causes the side wall to catastrophically collapse with the configuration of the cup-shaped member being inverted to permanently break the electric current path with a cover mounted terminal. A composite cover (8^iv, 8^v) includes a membrane layer in which the cup-shaped member is formed and which can also include a pressure vent (12g).

Claims

1. Current interrupt apparatus for use with an electrochemical cell having a housing with an open end and comprising a cover having a support layer receivable in the open end co-extensive therewith to close the open end of the electrochemical cell, the electrochemical cell having a positive and a negative terminal, an aperture formed in the support layer, a membrane having at least a portion formed into a cup-shaped member having a generally flat end wall, the cup-shaped member having a side wall depending from the flat end wall extending along a length to a support portion, the support portion being attachable to the support layer with the cup-shaped member being in alignment with the aperture and with the side wall extending in a direction toward the interior of the housing and with the flat end wall generally lying in a plane parallel to a plane in which the cover lies, said membrane and the support layer forming a composite in which they are co-extensive with one another and with the open end of the electrochemical cell, an electrical current path formed between an electrode within the housing and one of the positive and negative terminals, the material of the membrane being chosen to have a selected material properties so that upon being subjected to a pressure level from within the housing above a predetermined level, the side wall will catastrophically collapse with the configuration of the cup-shaped member changing to an opposite, inverted configuration with the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the plane in which the cover lies, the catastrophical collapse of the side wall interrupting the current path.

2. Current interrupt apparatus for use with an electrochemical cell according to claim 1 in which the electromechanical cell is prismatic in configuration.

3. Current interrupt apparatus for use with an electrochemical cell according to claim 1 in which the plane in which the flat end wall lies forms an angle greater than 90°

with the side wall of the cup-shaped member.

4. Current interrupt apparatus for use with an electrochemical cell having a housing formed with an open end and comprising a cover having a support layer receivable in the open end co-extensive therewith to close the open end of the electrochemical cell, the electrochemical cell having a positive and a negative terminal, an aperture formed in the support layer, a membrane having at least a portion formed into a cup-shaped member having a generally flat end wall, the cup-shaped shaped member having a side wall depending from the flat end wall extending along a length to a support portion, the support portion being attachable to the support layer with the cup-shaped member being in alignment with the aperture and with the side wall extending in a direction toward the interior of the housing and with the flat end wall generally lying in a plane parallel to a plane in which the cover lies, an electrical current path formed between an electrode! within the housing and one of the positive and negative terminals, one of the positive and negative terminals comprising an electrically conductive member having an outer, annular flange portion with an outer periphery and upper and lower opposed face surfaces, the apparatus further comprising an electrically conductive crimp ring and an electrically insulative sleeve, the support potion of the cup-shaped member being disposed about the outer periphery of the annular flange portion and being in contact with both the upper and lower opposed surfaces, the annular flange portion and support portion received in the electrically insulative sleeve and crimped to the crimp ring with the electrically insulative sleeve electrically separating the cup-shaped member and support member from the crimp ring and providing an elongated tortuous fluid seal path therebetween and the crimp ring being fixedly mounted to the cover in fluid sealed relation, the material of the membrane being chosen to have a selected material properties so that upon being subjected to a pressure level from within the housing above a predetermined level, the side wall will catastrophically collapse with the configuration of the cup-shaped member changing to an opposite, inverted configuration with the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the plane in which the cover lies, the catastrophical collapse of the side wall interrupting the current path.

5. Current interrupt apparatus for use with an electrochemical cell having a housing formed with an open end and comprising a cover having a support layer receivable in the open end co-extensive therewith to close the open end of the electrochemical cell, the electrochemical cell having a positive and a negative terminal, an aperture formed in the support layer, a membrane having a least a portion formed into a cup-shaped member having a generally flat end wall, the cup-shaped member having a side wall depending from the flat end wall extending along a length to a support portion, the support portion being attachable to the support layer with a cup-shaped member being in alignment with the aperture and with the side wall extending in a direction toward the interior of the housing and with the flat end wall generally lying in a plane parallel to a plane in which the cover lies, an electrical current path formed between an electrode within the housing and one of the positive and negative terminals, said cup-shaped membrane being formed of electrically conductive material and being part of the current path and further comprising an electrically conductive plate welded to the flat end wall on the side thereof facing the interior of the housing, the electrode being connected to the electrically conductive plate, the material of the membrane being chosen to have a selected material properties so that upon being subjected to a pressure level from within the housing above a predetermined level, the side wall will catastrophically collapse with the configuration of the cup-shaped member changing to an opposite, inverted configuration with the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the plane in which the cover lies, the catastrophical collapse of the side wall breaking the weld between the flat end wall and the electrically conductive plate to interrupt the electric current path.

6. Current interrupt apparatus for use with an electrochemical cell having a housing formed with an open end and comprising a cover having the support layer receivable in the open end co-extensive therewith to close the open end of the electrochemical cell, the electrochemical cell having a positive and a negative terminal, an aperture formed in the support layer, a membrane having at least a portion formed into a cup-shaped member having a generally flat end wall, the cup-shaped member having a side wall depending from the flat end wall extending along a length to a support portion, the support portion being attachable to the support layer with the cup-shaped member being in alignment with the aperture and with the side wall extending in a direction toward the interior of the housing and with the flat end wall generally lying in a plane parallel to a plane in which the cover lies, an electrically conductive support member having an outer periphery and an opening therethrough, the support portion of the cup-shaped member received about the outer periphery of the support member, a terminal plate and an electrically insulative annular member received on the support member, an electrically insulative, flexible sealing sleeve within which the support of the cup-shaped member, the support member, terminal plate and insulative annular member are received and a crimp ring crimping the terminal plate, insulative annular member, support portion and support member together with the terminal plate electrically isolated from the support portion and support member, the crimp ring extending through the aperture and being hermetically attached to the cover, a movable electrical contact electrically connected to the terminal plate and normally biased into electrical engagement with the support member, an electrically insulative motion transfer member having a portion disposed adjacent to the flat end wall and being received through the opening in the support member and aligned with the movable contact, the motion transfer member transferring motion from the flat end wall to the movable contact upon catastrophic collapse of the side wall to move the movable contact permanently out of engagement with the support member, an electrical current path formed between an electrode within the housing and one of the positive and negative terminals, the material of the membrane being chosen to have a selected material properties so that upon being subjected to a pressure level from within the housing above a predetermined level, the side wall will catastrophically collapse with the configuration of the cup-shaped member changing to an opposite, inverted configuration with the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the plane in which the cover lies, the catastrophical collapse of the side wall interrupting the current path.

7. Current apparatus for use with an electrochemical cell according to claim 6 in which the motion transfer member is integrally formed with the insulative annular member, the insulative annular member comprising an annular portion with an arm extending radially inwardly from the annular portion to a central portion, the motion transfer member being formed by a leg depending from a free end portion of the arm, and a reduced thickness hinge formed in the arm.

8. Current interrupt apparatus for use with an electrochemical cell according to claim 6 in which the motion transfer member is integrally formed with the insulative annular member, the insulative annular member comprising an annular portion defining a central portion with at least two arms extending inwardly in a spiral to a central portion having a contact receiving opening to provide the capability of vertical motion of the central portion, a stationary contact portion of the support member normally extending through the contact receiving opening and the motion transfer member being formed by at least one leg depending from the central portion.

9. Current interrupt apparatus for use with an electrochemical cell having a housing formed with an open end and comprising a cover having a support layer receivable in the open end co-extensive therewith to close the open end of the electrochemical cell the electrochemical cell having a positive and a negative terminal, an aperture formed in the support layer, a membrane having at least a portion formed into a cup-shaped member having a generally flat end wall, the cup-shaped member having a side wall depending from the flat end wall extending along a length to a support portion, the support portion being attachable to the support layer with the cup-shaped member being in alignment with the aperture and with the side wall extending in a direction toward the interior of the housing and with the flat end wall generally lying in a plane parallel to a plane in which the cover lies said support portion of the cup-shaped member being hermetically attached directly to the cover and the cover being crimped to and electrically isolated from the housing, an electrical current path formed between an electrode within the housing and one of the positive and negative terminals, the material of the membrane being chosen to have a selected material properties so that upon being subjected to a pressure level from within the housing above a predetermined level, the side wall will catastrophically collapse with the configuration of the cup-shaped member changing to an opposite, inverted configuration with the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the plane in which the cover lies, the catastrophical collapse of the side wall interrupting the current path.

10. Current interrupt apparatus for use with an electrochemical cell according to claim 9 in which the cover has an inside surface facing the interior of the housing and the support portion is welded to the inside surface.

11. Current interrupt apparatus for use with an electrochemical cell according to claim 9 in which the cover is formed of clad material having first and second layers and the material is rolled over around the aperture so that the layer of the cover facing the interior of the housing is rolled over to face away from the interior and the support portion is welded to the rolled over portion of the layer facing away from the interior of the housing.

12. Current interrupt apparatus for use with an electrochemical cell having a housing formed with an open end and comprising a cover having a support layer receivable in the open end co-extensive therewith to close the open end of the electrochemical cell, the electrochemical cell having a positive and a negative terminal, an aperture formed in the support layer, a membrane having at least a portion formed into a cup-shaped member having a generally flat end wall, the cup-shaped member having a side wall depending from the flat end wall extending along a length to a support portion, the support portion being attachable to the support layer with the cup-shaped member being in alignment with the aperture and with the side wall extending in a direction toward the interior of the housing and with the flat end wall generally lying in a plane parallel to a plane in which the cover lies an electrical current path formed between an electrode within the housing and one of the positive and negative terminals, the material of the membrane being chosen to have a selected material properties and a generally circular groove of reduced thickness formed in the flat end wall of the cup-shaped member at a distance from the side wall to compensate for variations in the geometry and material properties of the cup-shaped member, so that upon being subjected to a pressure level from within the housing above a predetermined level, the side wall will catastrophically collapse with the configuration of the cup-shaped member changing to an opposite, inverted configuration with the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the plane in which the cover lies due to such pressure level acting on the flat end wall creating stress in the side wall effectively through a moment arm, the catastrophical collapse of the side wall interrupting the current path.

13. Current interrupt apparatus for use with an electrochemical cell having a housing with a cover and having a cup-shaped member with a generally flat end wall and a side wall depending therefrom to support portion in which the cup-shaped member is mounted in an aperture formed in the cover and the side wall protrudes from the support portion into the interior of the housing to be exposed to fluid pressure generated in the housing which creates stress in the side wall effectively acting through a moment arm comprising the method steps of adjusting the effective length of the moment arm by choosing a radius between the flat end wall and the side wall to compensate for variations in geometry and material properties of the cup-shaped member.

14. In an electrochemical cell having a housing with a cover and having a cup-shaped member with a generally flat end wall and a side wall depending therefrom to a support portion in which the cup-shaped member is mounted in an aperture formed in the cover and the side wall protrudes from the support portion into the interior of the housing to be exposed to fluid pressure generated in the housing which creates stress in the side wall effectively acting through a moment arm comprising the method steps of adjusting the effective length of the moment arm by forming a generally circular groove of reduced thickness in the end wall adjacent to the side wall at a distance from the side wall selected to compensate for variations in geometry and material properties of the cup-shaped member.

15. Current interrupt apparatus for use with an electrochemical cell having a housing with a cover and having a positive and a negative terminal, the cover having an outer periphery and being a composite comprising a first support layer and a second membrane layer lying generally in a first plane and with each layer formed with an upstanding flange extending around the outer periphery for welding attachment with the housing with the membrane layer disposed between the support layer and the housing, the support having at least three apertures, the second membrane layer having an aperture aligned with the first aperture in the support layer, an electrically conductive rivet received through the first aperture in the support layer and the aperture in the membrane layer aligned with an electrically insulative sleeve between the rivet and the layers, the rivet having an externally exposed, relative to the housing, top portion and an internally exposed, relative to the housing, lower portion for connection to an electrical strap, the support layer having a second aperture in the support layer with the membrane layer extending across the second aperture, the membrane layer being formed with a coined portion aligned with the second aperture to serve as a pressure vent, a third aperture in the support layer, the membrane layer formed with a cup-shaped portion having a side wall extending downwardly from the plane to a generally flat end wall and aligned with the third aperture, the flat end wall lying in a plane parallel to the first plane, the material of the membrane being chosen to have selected material properties being chosen so that upon being subjected to a pressure level from within the housing above a predetermined level, the pressure will exceed the ultimate strength of the side wall material causing the side wall to catastrophically collapse with the configuration of the cup-shaped portion changing to an opposite, inverted configuration with at least a portion of the side wall extending in a direction away from the interior of the housing and with the flat end wall continuing to lie generally in a plane generally parallel to the first plane.

16. Current interrupt apparatus according to claim 15 in which the second aperture of the support layer is defined by a downwardly extending flange.

17. Current interrupt apparatus according to claim 15 further comprising a electrically insulative motion transfer member supported on the support layer and having a portion extending into the cup-shaped portion and an electrically conductive member cantilever mounted on a terminal member above the motion transfer member, the cantilever mounted member having a free distal end having a contact portion, an electrically conductive strap attached to the top portion of the rivet and having an end portion disposed beneath the contact portion whereby collapse of the side wall of the cup-shaped member will move the motion transfer member and, in turn, the cantilever mounted member out of electrical engagement with the electrically conductive strap.

18. Current interrupt apparatus according to claim 15 further comprising an electrically conductive terminal having an upper terminal portion and a lower portion having opposite ends, one opposite end mounted on the support layer electrically insulated therefrom on one side of the cup-shaped portion and the opposite end electrically connected to but movable from the support layer on another side of the cup-shaped portion and an electrically insulative motion transfer motion transfer member extending from the lower portion of the terminal into the cup-shaped portion whereby collapse of the side wall of the cup-shaped portion will move the motion transfer member and, in turn, the lower portion of the terminal out of engagement with the support layer.

19. Current interrupt apparatus according to claim 17 in which the opposite end of the lower portion of the terminal is attached to the support layer with a weak, frangible weld.

20. Apparatus for use with an electrochemical cell having a housing with a cover and having a positive and a negative terminal, the cover having an outer periphery and being a composite comprising a first support layer and a second membrane layer lying generally in a first plane and with each layer formed with an upstanding flange extending around the outer periphery for welding attachment with the housing with the membrane layer disposed between the support layer and the housing, the support having at least two apertures, the second membrane layer having an aperture aligned with the first aperture in the support layer, an electrically conductive rivet received through the first aperture in the support layer and the aperture in the membrane layer aligned with an electrically insulative sleeve between the rivet and the layers, the rivet having an externally exposed, relative to the housing, top portion and an internally exposed, relative to the housing, lower portion for connection to an electrical strap, the support layer having a second aperture in the support layer with the membrane layer extending across the second aperture, the membrane layer being formed with a coined portion aligned with the second aperture to serve as a pressure vent.