Current interrupt device for battery cells

Abstract

The present disclosure provides a "current interrupt device for a battery cell". A battery cell includes: an electrode; a terminal; and a current interrupt device, which is configured to electrically isolate the terminal from the electrode. The current interrupt device includes: a plate, which is connected to the electrode and defines a hole; and a diaphragm, which is connected to the terminal and connected to the plate to form a top plate of the hole. The cover of the current interrupt device is connected to the plate to form a bottom plate of the hole. A dielectric fluid is disposed in the hole. The diaphragm and the cover are configured to move toward the terminal in response to the pressure within the battery exceeding a threshold value to separate the diaphragm from the plate to form a gap between the two and release the fluid into the gap, thereby preventing the current from arcing across the gap.

Description

Technical Field

[0001] The present disclosure relates to traction battery assemblies for use in electric or hybrid vehicles, and more particularly to current interrupt devices for battery cells. Background Art

[0002] Vehicles such as battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and strong hybrid electric vehicles (FHEVs) contain a traction battery assembly to serve as an energy source for the vehicle. The traction battery may include components and systems that help manage vehicle performance and operation. The traction battery may also include high voltage components. Summary of the invention

[0003] According to one embodiment, a battery cell includes: an electrode; a terminal; and a current interruption device, the current interruption device being configured to electrically isolate the terminal from the electrode. The current interruption device includes: a plate connected to the electrode and defining a hole; and a diaphragm connected to the terminal and linked to the plate to form a top plate of the hole. The cover of the current interruption device is linked to the plate to form a bottom plate of the hole. A dielectric fluid is disposed in the hole. The diaphragm and the cover are configured to move toward the terminal in response to a pressure within the battery exceeding a threshold value to separate the diaphragm from the plate to form a gap between the two and release the fluid into the gap, thereby preventing arcing of the current across the gap.

[0004] According to another embodiment, a current interruption device for a battery cell includes: a plate defining a hole; and a diaphragm attached to the plate and covering the top of the hole. The current interruption device also includes a cover that seals the bottom of the hole. A dielectric fluid is disposed in the hole. The current interruption device is configured such that the diaphragm and the cover are movable to separate the diaphragm from the plate to form a gap and release the fluid into the gap in response to a battery pressure exceeding a threshold.

[0005] According to another embodiment, a battery cell includes: an electrode; a terminal; and a current interruption device configured to mechanically disconnect the terminal from the electrode. The current interruption device includes: a cavity filled with a dielectric fluid; and a movable cover that seals the cavity and forms a current path between the electrode and the terminal when in a sealed position and inhibits the current path when in a ruptured position, the ruptured position allowing the fluid to leak to further inhibit the path. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a perspective view of a battery cell.

[0007] Figure 2 is a cross-sectional view of the battery cell along cutting line 2 - 2 , wherein the current interrupt device is in a normal position.

[0008] Figure 3 is a partial perspective view of a current interrupting device.

[0009] Figure 4 is a bottom view of a plate of a current interrupt device.

[0010] Figure 5 is a cross-sectional view of the battery cell along the cutting line 2 - 2 , wherein the current interrupt device is in a separated position. DETAILED DESCRIPTION

[0011] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be magnified or minimized to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as restrictive, but only as a representative basis for teaching those skilled in the art to adopt the embodiments in various ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the accompanying drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of the features shown provides representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0012] A typical electric or hybrid electric vehicle may include one or more electric machines powered by a traction battery assembly. The electric machine may act as a motor to provide propulsion. The electric machine may also act as a generator to recover energy through regenerative braking to charge the traction battery assembly.

[0013] The traction battery may provide a high voltage direct current (DC) output from one or more battery cell arrays (sometimes referred to as battery cell stacks) within the traction battery. The battery cell array may include one or more battery cells. The traction battery may be electrically connected to one or more power electronics modules that regulate power to the electric machine. The power electronics modules may be electrically connected to the electric machine and provide the ability to transfer power bidirectionally between the traction battery and the electric machine. For example, a typical traction battery provides a DC voltage, while the electric machine requires a three-phase alternating current (AC) voltage.

[0014] The vehicle can be recharged by an external power source. The external power source is a connection to an electrical outlet. The external power source can be electrically connected to an electric vehicle supply equipment (EVSE). The EVSE can provide circuits and controls to regulate and manage the transfer of electrical energy between the power source and the vehicle. The external power source can provide DC or AC power to the EVSE. The EVSE can have a charging connector for plugging into a charging port of the vehicle. The charging port can be any type of port configured to transfer power from the EVSE to the vehicle. The charging port can be electrically connected to a charger or an onboard power conversion module. The power conversion module can regulate the power supplied from the EVSE to provide the appropriate voltage and current levels to the traction battery. The power conversion module can interface with the EVSE to coordinate the power delivery to the vehicle. The various components discussed can have one or more associated controllers to control and monitor the operation of the components. The controller can communicate via a serial bus (e.g., a controller area network (CAN)) or via discrete conductors.

[0015] The battery cell is configured to convert the stored chemical energy into electrical energy. The battery may include a can (housing), a positive electrode (cathode), and a negative electrode (anode). The electrolyte may allow ions to move between the anode and cathode during discharge, and then return during recharging. The terminals allow current to flow out of the battery cell for use by the vehicle. When positioned in an array with multiple battery cells, the terminals of each battery cell may be aligned with opposite terminals (positive and negative) adjacent to each other, and bus bars may help facilitate series connection between multiple battery cells. The battery cells may also be arranged in parallel with similar terminals (positive and positive or negative and negative) adjacent to each other, or may be arranged in series-parallel combinations.

[0016] Reference Figure 1 , a battery cell 20 (such as a prismatic cell) may include a can 22 having a pair of opposing major sides 24, a pair of opposing minor sides 26, a top 28, and a bottom 30. At least one terminal 32 is disposed on the top 28. In this example, the top 28 may be referred to as the terminal side of the can 22. The battery 20 shown includes both a positive terminal 32a and a negative terminal 32b on the top 28. The can 22 defines an interior. A positive electrode (cathode) 44, a negative electrode (anode) 42, and an electrolyte are disposed in the interior. The negative terminal 32b includes an outer portion 34 disposed on the outer surface of the can 22 and an inner portion 36 electrically connected to the anode 42 via a first current path. The positive terminal 32a also includes an outer portion 38 disposed on the outer surface of the can 22 and an inner portion 40 electrically connected to the cathode 44 via a second current path.

[0017] During charging and discharging of the battery cell 20, internal pressure may build up within the interior of the can 22. Ideally, these internal pressures will not exceed a threshold value. The battery 20 may include a current interrupt device 50 configured to interrupt an associated one of the first current path and the second current path in response to the internal pressure exceeding the threshold value to de-energize the battery 20. De-energizing the battery 20 via the current interrupt device 50 reduces the possibility of further increasing the pressure within the can 22.

[0018] Reference Figure 2 and Figure 3 In one embodiment, the current interrupt device 50 is associated with the positive terminal 32a and is physically disposed between the cathode 44 and the inner portion 40. In other embodiments, the device 50 can be associated with the negative terminal 32b. The device 50 can be attached to the underside 53 of the top 28 below the positive terminal 32a. The current interrupt device 50 is configured to de-energize the battery 20 by physically disconnecting the terminal 32a from the cathode 44 to create an open circuit in the second electrical path.

[0019] The current interruption device 50 may include an interruption member 52 having a fixed support 54 and a movable diaphragm 62. The diaphragm 62 may be disc-shaped. The interruption member 52 is formed of a conductive material. The support 54 is attached to the inner portion 40 of the positive terminal 32a. An upper insulating layer 60 may be disposed between the lower side 53 of the top 28 and the top surface 56 of the support 54 to electrically insulate the interruption member 52 from the tank 22. The support 54 may be circular and have an annular side wall 58 extending downward from the top surface 56. The diaphragm 62 is attached to the side wall 58 around the periphery 64 of the diaphragm 62 by welding, laser welding, brazing, ultrasonic welding, etc. The diaphragm 62 may include a main portion 66 and a protrusion 68 extending downward from the lower surface of the main portion 66. The protrusion 68 may be cylindrical and located at the center of the diaphragm 62. A conductive plate 70 is disposed below the diaphragm 62, and a lower insulating layer 72 is disposed between the main portion 66 and the plate 70. The plate 70 may be attached to a lower insulating layer 72 which is connected to the upper insulating layer 60 to suspend the plate 70 below the diaphragm 62. The conductor 74 ( Figure 1 ) connects plate 70 to cathode 44.

[0020] Reference Figure 2 and Figure 4, plate 70 defines hole 76, and lower insulating layer 72 defines hole 78. Holes 76 and 78 can be circular and concentric with each other. The diameter of hole 78 can be larger than the diameter of hole 76 to expose the upper surface 80 of plate 70. Protrusion 68 extends through hole 78 to contact upper surface 80. The diameter of hole 76 and the diameter of protrusion 68 can be substantially matched so that the side wall of protrusion 68 is placed against the upper edge of hole 76. Diaphragm 62 and plate 70 can be electrically and physically connected to each other by welding, brazing, laser welding, ultrasonic welding, etc.

[0021] A cover 84 is disposed on the lower surface 82 of the plate 70 to cover the bottom of the hole 76. The cover 84 may be a thin disk concentric with the hole 76. The diameter of the cover 84 may be smaller than the diameter of the diaphragm 62. The periphery of the cover 84 may be attached around the lower edge of the hole 76. The cover 84 may be formed of metal, plastic, fabric, neoprene, polypropylene, silicone, etc.

[0022] The diaphragm 62, the plate 70 and the cover 84 cooperate to define a fluid chamber 86 in the hole 76, wherein the projection 68 is used as a lid to form a top plate 88 of the chamber, the cover 84 forms a bottom plate 90 of the chamber, and the plate 70 defines a sidewall 92 of the chamber. A dielectric fluid 94 is disposed in the chamber 86. The dielectric fluid 94 can be contained in a bag, or can be freely disposed in the chamber 86, in which case the diaphragm 62 and the cover 84 accommodate the fluid in the hole 76. The dielectric fluid 94 can be a transformer oil, such as a mineral oil or a synthetic oil. The mineral oil can be a naphthenic oil or a paraffin oil. The synthetic oil can be a silicone oil. The dielectric fluid 94 can have a dielectric strength greater than the maximum voltage design limit of the battery system.

[0023] Figure 2 Current interrupt device 50 is shown in a normal operating position (also referred to as an unbroken, connected or sealed position) in which diaphragm 62 is joined to plate 70 to form an electrical path between terminal 32a and cathode 44. Cover 84 is in a raised position in which cover 84 protrudes at least slightly downwardly from plate 70.

[0024] Reference Figure 5 , the cover 84 is configured to flex upward and enter the hole 76 in response to the internal pressure in the battery 20 exceeding the threshold value. This can be referred to as the recessed position. Since the fluid 94 is incompressible, when the internal fluid pressure exceeds the threshold value, the flexing force of the cover 84 is transmitted to the diaphragm 62 so that the diaphragm 62 moves upward to the separation position separating the protrusion 68 from the plate 70. (The separation position can also be referred to as a rupture or disconnection position.) This creates an open circuit in the electrical path to de-energize the battery 20. When the diaphragm 62 moves to the separation position, the dielectric fluid 94 is released from the fluid chamber 86. The fluid 94 flows into the gap 102 defined between the separated diaphragm 62 and the plate 70 to form a dielectric barrier across the gap 102. The fluid barrier prevents arcing of the current across the gap 102.

[0025] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms covered by the claims. The words used in the specification are descriptive rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments can be combined to form other embodiments of the present invention that may not be explicitly described or shown.

[0026] According to the present invention, there is provided a current interruption device for a battery cell, the current interruption device having: a plate defining a hole; a diaphragm coupled to the plate and covering the top of the hole; a cover sealing the bottom of the hole; and a dielectric fluid disposed in the hole, wherein in response to a battery pressure exceeding a threshold value, the diaphragm and the cover are movable to separate the diaphragm from the plate to form a gap and release the fluid into the gap.

[0027] According to one embodiment, the cover is disc-shaped and has an edge portion joined to the plate.

[0028] According to one embodiment, the diaphragm is a disk and the diameter of the diaphragm is smaller than the diameter of the cover.

[0029] According to one embodiment, the plates are electrically connected to electrodes and the diaphragms are electrically connected to terminals.

[0030] According to one embodiment, the diaphragm comprises a main portion and a protrusion extending from the main portion, the protrusion being sized to engage the top of the hole, and wherein the disc is joined to the plate around a perimeter of the protrusion.

[0031] According to one embodiment, said protrusion is cylindrical.

[0032] According to one embodiment, the cover is formed from metal.

[0033] According to one embodiment, the cover is formed from plastic.

[0034] According to one embodiment, the dielectric fluid is transformer oil.

[0035] According to the present invention, a battery cell is provided, the battery cell having: an electrode; a terminal; and a current interruption device, the current interruption device being configured to electrically isolate the terminal from the electrode, the current interruption device comprising: a plate connected to the electrode and defining a hole, a diaphragm connected to the terminal and joined to the plate to form a top plate of the hole, a cover, the cover joined to the plate to form a bottom plate of the hole, and a dielectric fluid disposed in the hole, wherein the diaphragm and the cover are configured to move toward the terminal in response to a pressure within the battery exceeding a threshold value to separate the diaphragm from the plate to form a gap between the two and release the fluid into the gap, thereby preventing arcing of current across the gap.

[0036] According to one embodiment, the cover is disc-shaped and has an edge portion joined to the plate.

[0037] According to one embodiment, the diaphragm comprises a main portion and a protrusion extending from the main portion, the protrusion being configured to engage with a top portion of the hole, and wherein the diaphragm is attached to the plate around a perimeter of the protrusion.

[0038] According to one embodiment, the electrode is a cathode.

[0039] According to one embodiment, the dielectric fluid is transformer oil.

[0040] According to the present invention, there is provided a battery cell having: electrodes; terminals; and a current interruption device, the current interruption device comprising: a cavity filled with a dielectric fluid; and a movable cover, the movable cover sealing the cavity and forming a current path between the electrode and the terminal when in a sealed position and inhibiting the current path when in a ruptured position, the ruptured position allowing the fluid to leak to further inhibit the path.

[0041] According to one embodiment, the current interrupt device further comprises a cap opposite the cover, and wherein the cover is configured to flex towards the cover in response to the pressure within the battery exceeding a threshold value to move the cover to the ruptured position.

[0042] According to one embodiment, the current interruption device further comprises a plate having a hole, the plate partially defining the cavity, wherein the plate is connected to the electrode and is attached to the cover when the cover is in the sealing position.

[0043] According to one embodiment, the current interruption device further comprises a cover, which is joined to the plate to form a floor of the cavity.

[0044] According to one embodiment, the cover is disc-shaped.

[0045] According to one embodiment, the dielectric fluid is transformer oil.

Claims

1. A current interruption device for a battery cell, the current interruption device comprising: a plate defining an aperture; a diaphragm attached to the plate and covering the top of the hole; a cover that seals the bottom of the hole; as well as A dielectric fluid is disposed in the aperture, wherein in response to a pressure within the battery cell exceeding a threshold, the diaphragm and the cover are movable to separate the diaphragm from the plate to form a gap and release the dielectric fluid into the gap.

2. The current interrupt device of claim 1, wherein the cover is disc-shaped and has an edge portion joined to the plate.

3. The current interrupt device of claim 2, wherein the diaphragm is a disk and the diameter of the diaphragm is smaller than the diameter of the cover.

4. The current interrupt device of claim 1, wherein the plate is electrically connected to an electrode and the diaphragm is electrically connected to a terminal.

5. The current interrupt device of claim 1, wherein the diaphragm includes a main portion and a protrusion extending from the main portion, the protrusion being sized to engage the top of the hole, and wherein the diaphragm is attached to the plate around a perimeter of the protrusion.

6. A current interrupt device as claimed in claim 5, wherein the protrusion is cylindrical.

7. The current interrupt device of claim 1, wherein the cover is formed of metal.

8. The current interrupt device of claim 1, wherein the cover is formed of plastic.

9. The current interrupt device of claim 1, wherein the dielectric fluid is transformer oil.

10. A battery cell, comprising: electrode; terminal; as well as a current interruption device configured to electrically isolate the terminal from the electrode, the current interruption device comprising: a plate connected to the electrode and defining an aperture, a diaphragm connected to the terminal and joined to the plate to form a top plate of the hole, a cover joined to the plate to form a floor of the well, and A dielectric fluid is disposed in the hole, wherein the diaphragm and the cover are configured to move toward the terminal in response to a pressure within the battery cell exceeding a threshold value to separate the diaphragm from the plate to form a gap therebetween and release the dielectric fluid into the gap to prevent arcing of current across the gap.

11. The battery cell of claim 10, wherein the cover is disc-shaped and has an edge portion joined to the plate.

12. The battery cell of claim 10, wherein the separator includes a main portion and a protrusion extending from the main portion, the protrusion being configured to engage with a top of the hole, and wherein the separator is coupled to the plate around a perimeter of the protrusion.

13. A battery cell, comprising: electrode; terminal; as well as A current interrupting device, the current interrupting device comprising: a cavity filled with a dielectric fluid; and a removable cover that seals the cavity and forms a current path between the electrode and the terminal when in a sealed position and inhibits the current path when in a ruptured position that allows leakage of the dielectric fluid to further inhibit the path.

14. The battery cell of claim 13, wherein the current interrupt device further comprises a cover opposite the cover, and wherein the cover is configured to flex toward the cover in response to pressure within the battery cell exceeding a threshold value to move the cover to the ruptured position.

15. The battery cell of claim 13, wherein the current interrupt device further comprises a plate having an aperture, the plate partially defining the cavity, wherein the plate is connected to the electrode and is joined to the cover when the cover is in the sealing position.

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