Overcharge Protection System for Prismatic Lithium-Ion Battery Cells with Biased Encapsulation

Abstract

A prismatic lithium-ion battery cell includes an enclosure having a lid. A power assembly disposed within the enclosure has a first (e.g., negative) side and a second (e.g., positive) side. A terminal pad is electrically coupled to the first side of the power assembly, and the lid (84, 62) is electrically coupled to the second side of the power assembly. The lid includes a spiral disk feature (120) disposed beneath the terminal pad and a reverse disk (104) disposed beneath the spiral disk feature. The reverse disk is configured to deflect upward in response to a pressure within the enclosure being greater than a first predefined pressure threshold to displace the spiral disk feature to contact the terminal pad, thereby creating an external short circuit between the first side and the second side of the power assembly. Subsequently, a portion of the power assembly fails in response to the external short circuit and interrupts current flow within the power assembly.

Description

[0001] This application is a divisional application of a patent application for an invention titled "Overcharge Protection System for Prismatic Lithium Ion Battery Cells with Biased Encapsulation", with an application date of August 1, 2017, an international application number of PCT / US2017 / 044955, and a national application number of 201 / 780047370.2.

[0002] Cross - Reference to Related Applications

[0003] This application claims the priority and benefit of U.S. Provisional Application No. 62 / 369,718, filed on August 1, 2016, titled "OVERCHARGE PROTECTION DEVICES FOR PRISMATIC CELLS", and claims the priority and benefit of U.S. Provisional Application No. 62 / 369,720, filed on August 1, 2016, titled "OVERCHARGE PROTECTION DEVICES FOR CELLS WITH NEUTRAL CANS", which are hereby incorporated by reference in their entirety for all purposes. Background of the Invention

[0004] The present disclosure generally relates to the field of batteries and battery modules. More specifically, the present disclosure relates to an overcharge protection system for prismatic lithium - ion battery cells.

[0005] This section is intended to introduce to the reader aspects of the technology that may be related to aspects of the present disclosure described below. This discussion is considered to be helpful in providing background information to the reader to facilitate a better understanding of the aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light and not as an admission of prior art.

[0006] Battery systems can provide a viable alternative or supplement to systems that operate based on fossil - fuel combustion. Certain motor vehicles (e.g., all - electric vehicles, hybrid - electric vehicles, mild - hybrid electric vehicles, or other types of "xEV") include battery systems to provide all or part of the vehicle's power. For example, homes, offices, buildings, and similar locations typically include backup power sources (e.g., gas - powered generators) that can be used in the event of a central power failure (e.g., due to inclement weather). Similarly, certain environments (e.g., temporary offices, temporary housing, or other environments remote from the power grid) may not necessarily be connected to the power grid and may instead rely on energy supplied by a relatively portable power source (e.g., an engine - driven generator). For these environments, fixed battery systems can be an attractive alternative, not only because they can emit relatively fewer emissions compared to combustion processes, but also because other energy sources such as wind and solar energy can be coupled to these fixed battery systems to enable energy capture for later use.

[0007] A lithium-ion battery module typically includes a number of lithium-ion battery cells that are electrically connected together in a suitable manner to store and provide charge, for example, within a stationary or automotive battery system. When the battery module receives power, the battery cells of the module are charged for later use. However, during this process, the battery cells can become overcharged, resulting in unstable conditions within and around the battery cells, potentially including thermal runaway, rupture, fire, and / or explosion of the battery cells. Thus, it is desirable to reduce the risk of overcharging the lithium-ion battery cells in order to reduce the risk of damage to the battery module or the stationary / automotive power system due to these unstable battery cell conditions. SUMMARY OF THE INVENTION

[0008] An overview of certain embodiments disclosed herein is set forth below. It should be understood that presenting these aspects is merely to provide a brief overview of these embodiments to the reader and that these aspects are not intended to limit the scope of the disclosure. Indeed, the disclosure may cover aspects that may not be set forth below.

[0009] In an embodiment, a prismatic lithium-ion battery cell includes an enclosure having a lid sealed to a can. A power assembly disposed within the enclosure has a first side (e.g., a negative side) and a second side (e.g., a positive side). A terminal pad is electrically coupled to the first side of the power assembly, and the lid is electrically coupled to the second side of the power assembly. The lid includes a spiral disc feature disposed below the terminal pad and a reverse disc disposed below the spiral disc feature. The reverse disc is configured to deflect upward in response to a pressure within the enclosure being greater than a first predefined pressure threshold to displace the spiral disc feature to contact the terminal pad, thereby creating an external short circuit between the first side and the second side of the power assembly. Subsequently, a portion of the power assembly fails in response to the external short circuit and interrupts the flow of current within the power assembly.

[0010] In another embodiment, a prismatic lithium-ion battery cell includes an enclosure having a lid sealed to a can. A power assembly is disposed within the enclosure and includes: a wound stack having at least one wound; a first current collector coupled to the negative electrode of the at least one wound; a second current collector coupled to the positive electrode of the at least one wound; a first terminal post coupled to the first current collector and extending through the lid; and a second terminal post coupled to the second current collector and coupled to the lid. The battery cell includes a first terminal pad coupled to the first terminal post and a second terminal pad coupled to the second terminal post. The lid includes a spiral disk feature disposed below the first terminal pad and a reverse disk disposed below the spiral disk feature. The reverse disk is configured to deflect upward in response to a pressure within the enclosure being greater than a first predefined pressure threshold and displace the spiral disk feature to contact the first terminal pad and form an external short circuit between the positive and negative electrodes of the power assembly via the spiral disk feature. Subsequently, a portion of the power assembly fails in response to the external short circuit and interrupts current flow within the power assembly.

[0011] In another embodiment, a prismatic lithium-ion battery cell includes an enclosure having a lid sealed to a can. A power assembly is disposed within the enclosure, including a positive side and a negative side, wherein the enclosure is electrically coupled to the positive side of the power assembly. Terminal pads are disposed above the lid of the enclosure and are electrically coupled to the negative side of the power assembly. The lid includes: a spiral disk feature disposed below the terminal pads; and a reverse disk that is sealed to the lid below the spiral disk feature. In response to a pressure within the enclosure being greater than a first predefined pressure threshold, the reverse disk is configured to deflect upward to displace the spiral disk feature to contact the terminal pads and form an external short circuit between the positive and negative sides of the power assembly via the spiral disk feature. The lid further includes a vent disk that is sealed to the lid and is configured to be activated at a second predefined pressure threshold to release effluent from the interior of the enclosure, wherein the first predefined pressure threshold is significantly less than the second predefined pressure threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Aspects of the present disclosure are better understood upon reading the following detailed description and referring to the drawings, in which:

[0013] Figure 1 is a schematic view of a stationary energy storage system according to an embodiment of the present invention, the stationary energy storage system including a stationary drawer-type housing and battery modules;

[0014] Figure 2 is according to an embodiment of the present invention Figure 1 is an exploded perspective view of a battery module of the stationary storage system shown;

[0015] Figure 3 is according to an embodiment of the present inventionFigure 1 Perspective view of a fixed energy storage drawer of a fixed storage system as shown;

[0016] Figure 4 Perspective view of a prismatic lithium-ion battery cell according to an embodiment of the present technology, the prismatic lithium-ion battery cell comprising an overcharge protection system.

[0017] Figure 5 According to an embodiment of the present technology Figure 4 Exploded view of a prismatic lithium-ion battery cell.

[0018] Figure 6A and Figure 6B Respectively are perspective view and cross-sectional view of an example cover of a prismatic lithium-ion battery cell according to an embodiment of the present technology Figure 5 as shown;

[0019] Figure 7 According to an embodiment of the present technology Figure 5 Perspective view of another example cover of a prismatic lithium-ion battery cell as shown, wherein the cover comprises a dual integrated spiral disc feature;

[0020] Figure 8A According to an embodiment of the present technology Figure 5 Perspective view of an example current collector of a prismatic lithium-ion battery cell as shown, the current collector lacking a fuse;

[0021] Figure 8B According to an embodiment of the present technology Figure 5 Perspective view of another example current collector of a prismatic lithium-ion battery cell as shown, the current collector comprising a fuse;

[0022] Figure 9 Cross-sectional view of an assembled current divergence device (CDD) of an overcharge protection system of a prismatic lithium-ion battery cell according to an embodiment of the present technology;

[0023] Figure 10 Flowchart of the process of a prismatic lithium-ion battery cell overcharge protection system with a CDD having a single integrated spiral disc feature interrupting the current flow between the terminal pads of the battery cell in response to an overcharge event;

[0024] Figure 11 Flowchart of the process of a prismatic lithium-ion battery cell overcharge protection system with a CDD having a dual integrated spiral disc feature interrupting the current flow between the terminal pads of the battery cell in response to an overcharge event;

[0025] Figure 12Ais a cross-sectional view of another embodiment of an assembled CDD of an overcharge protection system for a prismatic lithium-ion battery cell prior to activation in accordance with an embodiment of the present technology;

[0026] Figure 12B According to an embodiment of the present technology, after activation Figure 12A Cross-sectional view of CDD;

[0027] Figure 13 According to an embodiment of the present technology Figure 12A and Figure 12B A flowchart of a process by which an overcharge protection system interrupts the flow of current between terminal pads of a battery cell in response to an overcharge event is shown;

[0028] Figure 14A is a cross-sectional view of another embodiment of an assembled CDD of an overcharge protection system for a prismatic lithium-ion battery cell prior to activation in accordance with an embodiment of the present technology;

[0029] Figure 14B According to an embodiment of the present technology, after activation Figure 14A a cross-sectional view of the CDD; and

[0030] Figure 15 is a cross-sectional view of a spiral disk feature having a relatively thick central portion and relatively thin leg portions in accordance with an embodiment of the present technology. DETAILED DESCRIPTION

[0031] One or more specific embodiments are described below. In order to provide a concise description of these embodiments, not all features of the actual implementations are described in this specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developer's specific goals, for example, to meet system-related and business-related constraints, which may vary from implementation to implementation. Furthermore, it should be understood that such development work may be complex and time-consuming, but is a routine task of design, construction, and manufacturing for those of ordinary skill having the benefit of this disclosure.

[0032] As described above, when a lithium-ion battery cell becomes overcharged, the unstable conditions (e.g., thermal runaway, cell rupture, cell fire, and / or cell explosion) that result within and around the cell can cause substantial damage to the surrounding system. When the cell is part of a larger battery module or even a larger stationary energy storage system, the resulting damage can include damage to the cell, the battery module, and other parts of the stationary energy storage system. Additionally, larger battery cells (e.g., 100 ampere-hours (Ah) or greater) provide increased capacity to the stationary energy storage system. However, these larger battery cells may potentially release a greater amount of energy due to an overcharge event, thereby increasing the risk of substantial damage to the battery module and / or stationary energy storage system that includes the cell. With this in mind, embodiments of the present invention relate to an overcharge protection system for a prismatic lithium-ion battery cell that is designed to appropriately interrupt the current within the cell to interrupt and limit or mitigate the damage caused by an overcharge event. Although the present technology is primarily discussed in the context of a stationary energy storage system, it should be understood that the inventions of the present disclosure are also applicable to automotive (e.g., vehicle) energy storage systems and other suitable types of energy storage systems.

[0033] More specifically, in response to an overcharge event, embodiments of the overcharge protection system of the present disclosure are designed and arranged to first short-circuit the cell externally. The current resulting from the short circuit is high enough to damage (e.g., melt) one or more internal components of the cell. This damage electrically disconnects at least one of the terminals (e.g., the positive terminal, the negative terminal, or both) from the corresponding electrode (e.g., the cathode or the anode) within the cell, thereby interrupting the internal current flow between the terminals of the cell. Thus, by interrupting this current flow in response to an overcharge event, embodiments of the overcharge protection system of the present disclosure prevent thermal runaway of the cell, thereby limiting damage within the battery module and / or energy storage system (e.g., a stationary energy storage system or a vehicle energy storage system) that includes the cell.

[0034] As discussed below, the overcharge protection system of the present disclosure includes at least one current diverting device (CDD) that externally shorts a prismatic lithium-ion battery cell in response to an increase in pressure within the interior of the battery cell. When the battery cell is overcharged, portions of the electrolyte within the battery cell may thermally expand, volatilize, and / or decompose, thereby substantially increasing the pressure within the interior of the battery cell. Other potential sources of outgassing during overcharge include decomposition of the active materials, as well as reactions between the active materials and the electrolyte and / or electrolyte additives. With this in mind, certain lithium-ion battery cells include venting features that eventually open to release this pressure once the pressure exceeds a specific threshold (typically about 6 bar or greater). In contrast, in certain embodiments, the overcharge protection system of the present disclosure includes a low-pressure current diverting device that is designed and arranged to interrupt the current in the battery cell in response to a significantly lower pressure (e.g., about 3 to 4 bar) within the interior of the battery cell. Thus, certain embodiments of the present invention are capable of responding more quickly (e.g., at a relatively low pressure, at a relatively low state of charge (SOC) of the battery cell) to interrupt the current in the battery cell in response to an overcharge condition prior to other protection features (e.g., venting features), thereby reducing the aforementioned risk of damage to the battery module and / or stationary energy storage system. Additionally, while capable of interrupting the current in the battery cell in response to a low activation pressure, the CDD of the present disclosure is designed and arranged to carry a sufficient amount of current during the short circuit to ensure that, in response to an overcharge event, the flow of current between the terminals of the battery cell is permanently interrupted, as discussed below.

[0035] The CDD designs of the present disclosure include three embodiments discussed in detail below. In all of these CDD designs, the lid of the battery cell includes at least one reverse disk that deforms when the pressure within the packaging of the battery cell reaches a predefined threshold. The deformation of the at least one reverse disk causes at least one conductive element (e.g., spiral disk feature, conductive member) to contact at least one terminal pad of the battery cell, thereby creating a short circuit between the terminals and ultimately resulting in the interruption of the current flow within the battery cell. More specifically, embodiments of the present disclosure include a battery cell having a single reverse disk and an unbiased or non-conductive encapsulation (as generally illustrated and discussed with respect to Figure 4 , Figure 5 , FIG. 12, Figure 13 and FIG. 14), where a single conductive element contacts two terminal pads to create a short circuit. Embodiments of the present disclosure also include a battery cell having a single reverse disk and a biased encapsulation (as generally illustrated and discussed with respect to Figure 9 and Figure 10Generally described and discussed), where a single conductive element contacts a single terminal pad to form a short circuit via the cover of the battery cell. Additionally, embodiments of the present disclosure include battery cells having dual reverse disks and an unbiased encapsulation (as described generally with respect to Figure 9 and Figure 11 Generally described and discussed), where two conductive elements contact different respective terminal pads to form a short circuit via the cover of the battery cell. Those skilled in the art will appreciate that, in accordance with the present disclosure, various aspects of these embodiments of the present disclosure may be combined or interchanged to provide CDD-protected battery cells with appropriate encapsulation (e.g., materials, bias) for different battery module designs.

[0036] In view of the foregoing, Figure 1 is a schematic diagram of an embodiment of a battery system 10, where a battery module 12 (e.g., a lithium-ion battery module 12) is configured for use in a stationary energy storage system 16. More specifically, the battery module 12 may be used as all or part of a stationary energy storage drawer 20. The stationary energy storage drawer 20 may be removably coupled to a stationary drawer housing 22 of the stationary energy storage system 16. Each stationary energy storage drawer 20 may include one or more battery modules 12, and the stationary energy storage system 16 may include one or more stationary energy storage drawers 20.

[0037] For example, the battery module 12 may have a plurality (e.g., between 10 and 20) of lithium-ion battery cells. The general configuration of the battery module 12 will be described in more detail below. One or more battery modules 12 may be incorporated into the stationary energy storage drawer 20, where several battery modules 12 may be connected to a larger stationary energy storage system 16 to provide the desired energy storage, energy conditioning, and / or energy output capabilities to a facility 24.

[0038] As illustrated, the facility 24 may include a building or a similar environment that is typically connected to a power grid 26 or other primary energy source to provide electricity for daily power consumption. However, in other embodiments, the facility 24 may be a facility that is not connected to the power grid 26 and thus relies entirely on other components to provide electrical energy (e.g., the stationary storage system 16). Additionally, the facility 24 may be a home or other environment. The stationary energy storage system 16 may be incorporated into or otherwise connected to the power grid of the facility 24 to provide electricity as needed. As a non-limiting example, the stationary energy storage system 16 may provide electricity to the facility 24 as a backup to the power grid 26 (e.g., due to a power outage), for power conditioning, to supplement power, or to compensate for power consumption of the power grid 26, etc.

[0039] Figure 2 is Figure 1Exploded perspective view of an embodiment of the battery module 12 of the fixed storage system 16 shown. As illustrated, certain embodiments of the battery module 12 include a plurality of prismatic lithium-ion battery cells 30 (also referred to herein as "batteries" for simplicity), and the plurality of prismatic lithium-ion battery cells 30 can be arranged in various configurations (e.g., orientation, stacking order). However, the batteries 30 will generally be provided in a certain quantity and configuration for a specific fixed application to have sufficient energy density, voltage, current, capacity, etc. As discussed in more detail below, in different embodiments, the battery 30 can have a polymer housing or a metal housing or a combination that encloses the electrochemically active components of the battery cell 30.

[0040] Figure 2 The battery module 12 includes a stack or array of battery cells 30, where the busbar carrier 32 is positioned above the terminals 34, 36 to achieve electrical interconnection of the terminals 34, 36 using the busbar assembly 38. The busbar assembly 38 generally electrically connects the battery cells 30 as an electrical assembly. In certain embodiments, the busbar assembly 38 can be integrated onto the busbar carrier 32 with other suitable features (e.g., voltage sensing connectors) in some cases.

[0041] For the illustrated embodiment, a traceboard 40 is positioned above the busbar assembly 38 such that the busbar assembly 38 is positioned between the traceboard 40 and the busbar carrier 32. A battery management system (BMS) 42 is integrated onto the traceboard 40 to connect the BMS 42 to any sensing features (e.g., temperature and / or voltage sensing features) and to achieve control over the overall operation of the battery 30 and the battery module 12. In some embodiments, the BMS 42 can also monitor and control the operation of the fixed energy storage drawer 20.

[0042] The housing 44 of the illustrated embodiment completely encloses the battery 30 and some or all of the features described above with respect to Figure 2 As illustrated, the module housing 44 takes the shape of the battery cells 30 that make it up (in this case, a prismatic outer shape). However, the housing 44 can be shaped into any shape suitable for a specific application. A cover 46 is provided above the BMS 42, the traceboard 40, and the busbar assembly 38 and is attached to the upper part of the battery module housing 44. The cover 46 is configured to substantially enclose the BMS 42, the traceboard 40, and the busbar assembly 38 to prevent unintentional contact with the electrical and control components. Thus, the cover 46 can be formed of an electrically insulating material, which can be the same as or different from the material forming the housing 44. In certain embodiments, the outer perimeter of the traceboard 40 can correspond to the inner perimeter of the cover 46.

[0043] Integrating the battery module 12 into the fixed energy storage drawer 20 can have many advantages and enable various configurations of the fixed energy storage drawer 20. For example, Figure 3 depicts an embodiment of the fixed energy storage drawer 20 having two battery modules 12 (e.g., a first battery module 12 and a second battery module 12) positioned side by side within the fixed drawer housing 52. Specifically, in Figure 3 , each battery module 12 is fastened within the fixed energy storage drawer 20 in an orientation in which the respective terminals 34, 36 of the battery cells 30 are axially oriented laterally with respect to the base 50 of the fixed drawer housing 22. The fixed energy storage drawer 20 of the present disclosure can include various types of battery modules 12 (e.g., having the same or different capacities, voltages, sizes, shapes) to enable flexible solutions for various fixed energy storage applications.

[0044] Figure 4 is a perspective view of an embodiment of a prismatic lithium-ion battery cell 60 according to an embodiment of the present invention. As used herein, "prismatic" refers to the generally box-shaped (e.g., polygonal) shape of the substantially rigid encapsulation 62 of the battery cell 60. Thus, it should be understood that the prismatic battery 60 of the present disclosure is different from a pouch battery cell having a substantially flexible laminated encapsulation. Additionally, it should be understood that the prismatic battery 60 of the present disclosure is also different from a cylindrical battery cell having a substantially rigid cylindrical encapsulation. Those skilled in the art will appreciate that these different battery shapes and encapsulation materials present different limitations and failure modes, and problems or solutions that are effective for one type of battery cell may not be applicable to other types of battery cells.

[0045] The illustrated encapsulation 62 of the prismatic lithium-ion battery cell 60 can generally be described as having a first substantially flat side 64 and a second substantially flat side 66 disposed opposite one another. Additionally, the encapsulation 62 includes a first end 68 and a second end 70 disposed opposite one another. In certain embodiments, the ends 68 and 70 can be substantially flat, rounded, or substantially flat with slightly rounded corners 72, as illustrated.

[0046] Figure 5 is Figure 4Exploded perspective view of an embodiment of a prismatic lithium-ion battery cell 60 as shown. The enclosure 62 of the illustrated battery cell 60 includes a can 80 that is coupled to (e.g., hermetically sealed to, welded to) a lid 84. In some embodiments, both the can 80 and the lid 84 may be made of metal (e.g., aluminum), while in other embodiments, one or both of the can 80 and the lid 84 may be made of an electrically insulating material (e.g., polymer, polypropylene plastic). Once sealed (e.g., via welding) together, the can 80 and the lid 84 form a substantially rigid enclosure that resists (e.g., prevents, stops) expansion due to increased pressure within the battery 60 (e.g., due to thermal expansion, due to an overcharge event) and due to externally applied pressure to the battery 60.

[0047] Within the can 80, the illustrated prismatic lithium-ion battery cell 60 includes a stack 85 having two electrode (e.g., cathode / anode) rolls 86 and 88. Each roll 86 and 88 includes a cathode layer and an anode layer as well as appropriate separator layers that are wound together to form the charge storage elements of the battery 60. In other embodiments, according to the present disclosure, the battery 60 may include only one roll, or include a stack 85 having three, four, five, or more rolls. As discussed in more detail below with respect to Figure 8A and Figure 8B collectors 92A and 92B, the collectors 92A and 92B are welded to the appropriate electrodes (e.g., cathode or anode) at the ends of the rolls 86 and 88 of the roll stack 85. Additionally, terminal posts 94A and 94B are welded to the collectors 92A and 92B, respectively, to produce an assembled electrical assembly 95 of the battery 60. The assembled electrical assembly 95 may be generally described herein as having a first side or negative side (e.g., corresponding to the collector 92A) and a second side or positive side (e.g., corresponding to the collector 92B) that are respectively coupled to terminal pads 112A and 112B. Additionally, an insulating wrapper 96 wraps around a sufficient amount of the electrical assembly 95 to electrically isolate the electrical assembly 95 from the can 80 of the battery cell 60.

[0048] The lid 84 is disposed above the electrical assembly 95, and the terminal posts 94A and 94B extend through corresponding openings 98A and 98B defined in the lid 84 (and are hermetically sealed within the corresponding openings 98A and 98B). The illustrated lid 84 includes an opening 100, and a vent disk 101 is sealed (e.g., welded) around the opening 100 to the bottom side 103 of the lid 84, where the top side 105 faces away from the electrical assembly 95. Additionally, the illustrated lid 84 includes an opening 102, and a reverse disk 104 is sealed (e.g., welded) around the opening 102 on the bottom side 103 of the lid 84, and a conductive element (e.g., a spiral disk feature 106 or another suitable conductive member) is welded to the top side 105 of the lid 84. The lid 84 also includes a fill hole 108 for adding electrolyte to the battery 60 after assembly.

[0049] In some embodiments, the reverse disk 104 can be made of a suitable metal or polymer material and can have suitable dimensions (e.g., thickness, diameter) to deflect (e.g., flip) when the pressure within the enclosure 62 of the battery 60 reaches or exceeds a specific threshold. In some embodiments, the vent disk 101 is sized, designed, and configured to activate at a threshold pressure that is at least 50% greater (e.g., between 50% and 80% greater) than the threshold pressure of the reverse disk 104 to ensure that the reverse disk 104 externally shorts the battery 60 before the effluent is released from the interior of the battery 60 through the vent disk 101.

[0050] In addition, by using the conductive elements of the present disclosure (e.g., the spiral disk feature 106, as discussed for the embodiments regarding Figure 5 , Figure 6, Figure 7 , Figure 9 and Figure 14, or another suitable conductive member 180, as discussed for the embodiments regarding Figure 12 and Figure 13 ), the reverse disk 104 of the present disclosure can be significantly thinner and can activate in response to a pressure that is significantly lower (e.g., less than 6 bar, about 3 to 4 bar) than the activation pressure for a design where an external short circuit would have to traverse a thicker reverse disk 104 (e.g., at an activation pressure greater than about 6 bar). That is, in the design of the present invention, the reverse disk 104 does not need to be part of the short - circuit path or does not need to carry a significant amount of current. In fact, in the design of the present invention, the reverse disk 104 deflects a conductive element having a significantly larger current - carrying capacity (e.g., the spiral disk feature 106 or the conductive member 180) to form an external short circuit with one or both of the terminal pads. For example, for the Figure 5 illustrated embodiment, once the reverse disk 104 is deployed to form a short - circuit path, the conductive element (i.e., the spiral disk feature 106) contacts both terminal pads 112A and 112B. It can be appreciated that in some embodiments, since the reverse disk 104 can be in electrical contact with the conductive element (e.g., the spiral disk feature 106 or the conductive member 180), for these embodiments, a small portion of the short - circuit current can traverse, energize, or pass through the reverse disk 104, the cover 84, and the enclosure 62 of the battery cell 60. However, the conductive element can be significantly thicker (e.g., 2 to 10 times, 5 to 10 times) than the reverse disk 104, or have a portion that is significantly thicker than the reverse disk 104. Accordingly, it is currently recognized that the conductive element (e.g., the spiral disk feature 106 or the conductive member 180) exhibits a significantly lower resistance than the reverse disk 104. Thus, for these embodiments, a significant portion of the short - circuit current traverses the lower - resistance spiral disk feature 106 or conductive member 180 rather than the reverse disk 104. In other embodiments discussed below, the reverse disk 104 can be via an electrically insulating layer (e.g., viaFigure 12A and Figure 12B is electrically insulated from the conductive element (e.g., conductive member 180) by the illustrated insulating layer 182), thereby substantially preventing or precluding a short-circuit current from reaching the reverse disk 104, the lid 84, or any other part of the encapsulation 62 of the battery cell 60. It will be appreciated that this substantially reduces the risk of electrical damage to components that may be in contact with the encapsulation 62 of the battery cell 60 within the battery module 12 during a short-circuit event. Accordingly, the CDD design of the present disclosure achieves improved current-carrying capacity, greater sensitivity (e.g., lower pressure threshold), and more short-circuit path options compared to other CDD designs.

[0051] In the illustrated embodiment, the polymeric terminal insulator 110 is disposed over the lid and provides selective electrical isolation between certain metallic features of the battery 60. For example, the terminal insulator 110 generally defines openings to allow certain components (e.g., terminal posts 94A and 94B, spiral disk features 106) to pass through (e.g., extend through, deflect through) the terminal insulator 110 as needed. Additionally, in certain embodiments, the terminal insulator 110 electrically isolates portions of the lid 84 from one or both of the terminal pads 112A and 112B.

[0052] The illustrated terminal pads 112A and 112B of the battery 60 are coupled to the terminal posts 94A and 94B, respectively, and are disposed over the terminal insulator 110 and the lid 84 of the battery cell 60. The illustrated battery 60 also includes electrically insulating terminal caps 114A and 114B disposed over portions of the terminal pads 112A and 112B, respectively, which help avoid accidental contact with the terminal pads 112A and 112B or between the terminal pads 112A and 112B. Additionally, the illustrated battery 60 includes a fill-hole seal disk 116 that seals the fill hole 108 of the lid 84 after the interior of the battery 60 has been filled with electrolyte, as described above.

[0053] Figure 6A is a perspective view of another embodiment of the lid 84 of the prismatic lithium-ion battery cell 60 according to the present invention. Figure 6B is taken along line 6B Figure 6A cross-sectional view of the embodiment of the lid 84. The illustrated lid 84 includes and / or defines certain features described above, including openings 98A and 98B corresponding to the terminal posts 94A and 94B, respectively, an opening 100 corresponding to the vent disk 101, and a fill hole 108. However, instead of Figure 5 the opening 102 shown in the lid 84 of Figure 6A and Figure 6BThe lid 84 includes an integrated helical disk feature 120 formed in relief. For example, the illustrated metal lid 84 can be manufactured using stamping and / or pressing operations that simultaneously form the features of the illustrated lid 84, including the integrated helical disk feature 120 formed in relief. Thus, compared to other designs, the illustrated integrated helical disk feature design reduces manufacturing time and cost and provides a more reliable (e.g., thicker, more controlled, more regular) connection between the helical member 120 and the lid 84 for external short circuits to cross.

[0054] Figure 7 is Figure 5 A perspective view of another embodiment of the lid 84 of the illustrated prismatic lithium-ion battery cell 60. Additionally, the illustrated lid 84 includes and / or defines the features described above, including openings 98A and 98B corresponding to terminal posts 94A and 94B, respectively, an opening 100 corresponding to the vent disk 101, and a fill hole 108. However, Figure 6A and Figure 6B the lid 84 includes dual integrated helical disk features 120A and 120B formed in relief. For embodiments of the CDD that include the illustrated lid 84, the lid 84 has dual integrated helical disk features 120A and 120B, and corresponding reverse disks 104 are sealed (e.g., welded) to the bottom side 103 of the lid 84 below each disk. The operation of the lid 84 having dual integrated helical disk features 120A and 120B is discussed below with respect to Figure 11 and.

[0055] Figure 8A and Figure 8B is Figure 5 A perspective view of different embodiments of the current collector 92A of the illustrated prismatic lithium-ion battery cell 60. The two illustrated current collectors 92A include extensions 130 that are welded to the corresponding electrodes of the rolls (e.g., rolls 86, 88), and also include platforms 132 to which the terminal posts 94A are welded, as described above. However, Figure 8B the illustrated embodiments of the current collector 92A include one or more fuses 134, while Figure 8A the illustrated embodiments of the current collector 92A lack any such fuse features.

[0056] Thus, it can be noted that in some embodiments, at least one of the current collectors (e.g., current collector 92A, current collector 92B, or both) that electrically couple an electrode (e.g., cathode or anode) to its corresponding terminal pad can include such a fuse 134 that preferentially fuses and fails before other parts of the electrical assembly 95 of the battery 60 in response to an external short circuit. In contrast, for embodiments that include Figure 8AIn an embodiment of the current collector 92A, when the battery 60 is short-circuited externally, an unexpected (e.g., unplanned, random) portion of the power assembly 95 fuses and fails, thereby interrupting the continuity between the electrode (e.g., cathode or anode) and the corresponding terminal of the battery cell. By disconnecting at least one electrode from the corresponding terminal in response to an induced external short circuit, embodiments of the present invention achieve automatic cut-off of the current within the battery 60 in response to an overcharge event, which protects the battery 60 from thermal runaway and limits damage within the battery module 12 and / or the stationary energy storage system 16 that includes the battery 60.

[0057] Figure 9 FIG. 4 is a cross-sectional view of an embodiment of an assembly current diverting device (CDD) 140 of an overcharge protection system for a prismatic lithium-ion battery cell 60. More specifically, for the embodiment of the CDD 140 shown and discussed below, opposite terminals (not shown) are electrically coupled to the lid 84 of the package 62 of the battery cell 60. In some embodiments, the positive or negative side of the power assembly 95 is electrically coupled to the lid 84, and the opposite side (e.g., positive or negative side) of the power assembly 95 is electrically coupled to the shown terminal 112A disposed above the reverse disk 104 and the spiral disk feature 106. It should be understood that Figure 9 the design shown also represents one terminal region of an embodiment of the CDD 140 that includes a reverse disk 104 and a spiral disk 106 disposed below two terminal pads 112, as described below with respect to Figure 9 FIGS. 8 and 9. Figure 11 as described.

[0058] In addition to including the components described above, Figure 9 the embodiment shown also includes a washer 142 positioned between the terminal post 92A and the lid 84. For embodiments in which the lid 84 is metal, the washer 142 electrically isolates the terminal post 94A from the lid 84. Figure 10 FIG. 7 is a flow chart of a process 150 in which an embodiment of an overcharge protection system for a prismatic lithium-ion battery cell 60 interrupts current flow between terminal pads 112A and 112B of the battery 60 in response to an overcharge event. The prismatic lithium-ion battery cell 60 has a CDD with a single integrated spiral disk feature 120 and a package 62 with a positive polarity. Thus, the discussion below is in the context of the CDD 140 shown in Figure 9 FIGS. 4-6. Figure 10For this example, the CDD 140 of the overcharge protection system includes a single reverse disk 104 and a single integrated spiral disk feature 120, which are disposed under a portion of the terminal pad 112A that is not electrically coupled to the cover 84 or the package 62 of the battery 60. As described above, another terminal pad 112B (not shown) is electrically coupled to the cover 84 and the package 62, resulting in a biasing (e.g., positive biasing) of the cover 84 and the package 62.

[0059] For this example embodiment, the process 150 shown begins with the pressure in the battery 60 increasing (block 152) in response to the aforementioned electrochemical processes (e.g., thermal expansion, electrolyte decomposition) occurring inside the battery 60 due to an overcharge event. When the pressure in the battery 60 reaches a pressure threshold, based on the size of the reverse disk 104, the reverse disk 104 deflects upward (e.g., outward from the interior of the battery 60, as indicated by the arrow 156 in Figure 9 ) (block 154). This deflection provides sufficient force to cause the spiral disk feature 120 to shift upward (e.g., in the direction 156) (e.g., deflect, bend, twist, and / or otherwise deform) toward the terminal pad 112A disposed above the integrated spiral disk feature 120 (block 158).

[0060] For the example shown, because the cover 84 is physically and electrically coupled to the spiral disk feature 120, physical contact between the spiral disk 120 and the terminal pad 112B forms a short circuit between the positive and negative sides of the power assembly 95 of the battery 60. In other words, because the cover 84 of the package 62 is biased (e.g., positively biased), physical contact between the integrated spiral disk feature 120 and the terminal pad 112A as described in block 158 forms a short circuit, as indicated by the arrow 159 (see Figure 9 ) between the positive and negative sides of the power assembly 95, where the short circuit current passes through the cover 84 of the battery (block 160). The power assembly 95 of the battery 60 resistively heats (block 162) in response to the external short circuit until a portion of the power assembly 95 (e.g., Figure 8B the fuse 134 shown or a random / unplanned portion) fails to respond to the resistive heating, thereby interrupting the internal circuit path and current between the terminal pads 112A and 112B. As the overcharge event abates / interrupts, the battery 60 then cools in response to the interruption of the internal circuit path between the terminal pads 112A and 112B.

[0061] Figure 11FIG. 170 illustrates the process by which an embodiment of the overcharge protection system of the present disclosure responds to an overcharge event in a battery cell having a neutral unbiased encapsulation 62 (e.g., the cover 84 is electrically insulated from the terminal pads 112A and 112B and the terminal posts 94A and 94B). For this embodiment, the CDD of the overcharge protection system includes two reverse discs and two corresponding integrated spiral disc features disposed respectively under portions of the terminal pads 112A and 112B. Thus, process 170 corresponds to an embodiment of the CDD of the cover 84 having Figure 7 which includes dual integrated spiral disc features 120A and 120B.

[0062] Similar to Figure 10 the process 150 shown, Figure 11 the process 170 shown begins with an increase in pressure in the battery 60 in response to an overcharge event (block 152). When the pressure in the battery 60 reaches a pressure threshold, based on the size of the reverse discs 104, the reverse discs 104 each deflect upward (e.g., as shown by the arrow 156 in Figure 9 ) (block 171). This deflection provides sufficient force to cause the integrated spiral disc features 120A and 120B to shift upward (e.g., as shown by the arrow 156 in Figure 9 ) (e.g., deflect, bend, twist, deform) toward the terminal pads 112A and 112B respectively (block 172). In this instance, in addition to the physical and electrical contact between the integrated spiral disc feature 120B and the terminal pad 112B, the physical contact between the integrated spiral disc feature 120A and the terminal pad 112A also forms a short circuit between the terminal pads 112A and 112B, where the short circuit current again passes through the cover 84 of the battery (block 174). Similar to Figure 10 the process 150, as Figure 11 shown, the power assembly 95 of the battery 60 resistively heats in response to an external short circuit (block 162) until a portion of the power assembly 95 fails (block 164), and as the overcharge event abates / interrupts, the battery 60 then cools in response to the interruption of the internal circuit path and current between the terminal pads 112A and 112B.

[0063] Figure 12A FIG. 221 is a cross-sectional schematic view of another embodiment of the CDD 140 of the assembly of the overcharge protection system of the prismatic lithium-ion battery cell 60 before activation. Figure 12B FIG. 224 is after activation Figure 12ACross-sectional view of the CDD. The illustrated embodiment includes certain components similar to those discussed above, including terminal pads 112A and 112B, terminal insulator 110, cover 84, and reverse disk 104. The illustrated reverse disk 104 is disposed between terminal pads 112A and 112B and in the central region below terminal pads 112A and 112B. The illustrated embodiment also includes a conductive element (e.g., conductive member 180), which is illustrated as a flat metal disk disposed above reverse disk 104. In other embodiments, conductive member 180 may be implemented as all or part of a helical disk feature coupled or integrated into cover 62 of battery cell 60. The illustrated design also includes an electrical insulation layer 182 disposed between conductive member 180 and reverse disk 104. For example, in certain embodiments, insulation layer 182 may include an adhesive to enable conductive member 180 to be attached to reverse disk 104. In other embodiments, insulation layer 182 may additionally or alternatively include snap features to fasten conductive member 180 to the surface of reverse disk 104.

[0064] Figure 14A is a cross-sectional schematic view of another embodiment of the assembled CDD 140 of the overcharge protection system of the prismatic lithium-ion battery cell 60 before activation. Figure 14B is after activation Figure 14A cross-sectional view of CDD 140. Similar to Figure 12A and Figure 12B the design shown, for Figure 14A and Figure 14B the design shown, the remaining portion of cover 62 and / or encapsulation 84 may be made of a conductive (e.g., metal) or non-conductive (e.g., polymer) material. For embodiments having a conductive cover 62 and / or encapsulation 84, cover 62 and encapsulation 84 may be electrically isolated from the two terminal pads 112A and 112B such that the encapsulation 84 of battery cell 60 is not biased until activation of the CDD, as Figure 12B and Figure 14B shown. For Figure 14A and Figure 14B the embodiments shown, the conductive element is implemented as a helical disk feature 106 disposed above reverse disk 104. Figure 14A and Figure 14B the embodiments shown lack the electrical insulation layer 182 disposed between the conductive element (e.g., conductive member 180 or helical disk feature 106) and reverse disk 104, as Figure 12A and Figure 12B shown. Thus, for Figure 14A and Figure 14B the embodiments shown, reverse disk 104 and cover 62 are in electrical contact with helical disk feature 106.

[0065] In addition, Figure 15 Cross-sectional view of the conductive element (i.e., the spiral disc feature 106) of the cover 84 of the illustrated battery cell 60, which can be used in embodiments of the CDD where the conductive element contacts two terminal pads 112A and 112B (e.g., Figure 5 as shown in FIG. 14). As Figure 15 shown, the spiral disc feature 106 includes a central portion 200 having a first thickness 201, which facilitates current passage between the terminal pads 112A and 112B. In certain embodiments, the central portion 200 of the spiral disc feature 106 can be used as and / or referred to as the conductive member 180 (e.g., Figure 12A the conductive member 180 in Figure 12B ). The relatively thick central portion 200 is coupled to the cover 84 via a plurality of legs 202 having a second thickness 203, which enables deflection of the central portion 200 via the reverse disc 104. As illustrated, in certain embodiments, the first thickness 201 can be significantly greater than the second thickness 203. In other words, for the illustrated embodiment (as Figure 14B shown), since the legs 202 of the spiral disc feature 106 do not need to carry the short-circuit current, the legs 202 can be significantly (e.g., 2 to 5 times) thinner than the central portion 200 of the spiral disc feature 106, which reduces the force required to shift the spiral disc feature 106 to contact the terminal pads 112A and 112B.

[0066] Figure 13 An example of the process 190 in which the CDD 140 shown in FIGS. 12 and 14 responds to an overcharge event within the battery 60. For this example, the cover 84 and the remainder of the encapsulation 62 of the battery 60 can be conductive (e.g., metal) and neutral, or can be non-conductive (e.g., polymer, plastic). Similar to the processes 150 and 170 discussed above, Figure 13 the process 190 shown begins with an increase in pressure within the battery 60 in response to an overcharge event (block 152). When the pressure within the battery 60 reaches a pressure threshold, based on the size of the reverse disc 104, the reverse disc 104 deflects upward, as indicated by the arrows 192 shown in Figure 12B and Figure 14B respectively (block 154). This deflection provides sufficient force to move the conductive element (e.g., the conductive member 180 or the spiral disc feature 106) upward (e.g., along Figure 12B and Figure 14Bthe arrow 192) is displaced (e.g., moved, translated, deflected) (block 194). The physical contact between the conductive element (e.g., conductive member 180 or spiral disk feature 106) and the two terminal pads 112A and 112B forms a short circuit between the terminal pads, where a substantial portion (e.g., the majority, most part) of the current passes through the conductive element (e.g., conductive member 180 or spiral disk feature 106), as indicated by the arrows 195 in Figure 12B and 14B respectively (block 196). For the Figure 12B illustrated embodiment, since the reverse disk 104 is electrically insulated from the conductive member 180, the short circuit current does not cross or energize the cover 84 or the package 62 of the battery 60. For the Figure 14B illustrated embodiment, since the reverse disk 104 is in electrical contact with the spiral disk feature 106 and since the legs 202 of the spiral disk feature 106 are coupled to the cover 84, a small portion of the short circuit current may cross or energize the cover 84 or the package 62 of the battery 60. However, as described above, at least a portion of the conductive element (e.g., the central portion 200 of the conductive member 180 or spiral disk feature 106) is significantly (e.g., 2 to 10 times) thicker than the reverse disk 104 and thus has a lower resistance. Therefore, in contrast to the reverse disk 104, the cover 84, or the package 62, a substantial portion of the short circuit current crosses the conductive element with the lower resistance (e.g., the conductive member 180, the central portion 200 of the spiral disk feature 106). Similar to the processes 150 and 170 discussed above, as Figure 13 illustrated, the power assembly 95 of the battery 60 resistively heats (block 162) in response to an external short circuit until a portion of the power assembly 95 fails (block 164), and as the overcharge event abates / interrupts, the battery 60 then cools in response to the interruption of the internal circuit path and current between the terminal pads 112A and 112B.

[0067] One or more embodiments of the present disclosure, individually or in combination, may provide one or more technical effects, including the manufacture of a battery module having a current diverting device (CDD) that externally shorts a prismatic lithium-ion battery cell in response to an increase in pressure within the battery. Certain embodiments of the lithium-ion battery cells of the present invention are capable of responding relatively quickly (e.g., at relatively low pressures and at relatively low states of charge (SOC) of the battery cell) to interrupt current in the battery cell in response to an overcharge condition, thereby reducing the risk of damage to the battery module and / or the stationary energy storage system. Additionally, while capable of interrupting current in the battery cell in response to a low activation pressure, the CDD of the present disclosure is designed and arranged to carry a sufficient amount of current during the short circuit to ensure that, in response to an overcharge event, the flow of current is permanently interrupted between the terminals of the battery cell. The technical effects and technical problems in this specification are exemplary and not restrictive. It should be noted that the embodiments described in this specification may have other technical effects and may solve other technical problems.

[0068] The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may have various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

Claims

1. A method for interrupting current within a battery cell, the battery cell including a package, an electrical assembly, and terminal pads, the package including a can and a lid sealed to the can, the electrical assembly having a first side and a second side and disposed within the package, the terminal pads being electrically coupled to the electrical assembly, the lid including a spiral disk and a reverse disk disposed below the spiral disk, the spiral disk being disposed below the terminal pads and including a central portion and a plurality of legs, the central portion being coupled to the lid by the plurality of legs, the method including: Deflecting the reverse disk in response to a pressure within the package being greater than a first predefined pressure threshold such that at least the central portion of the spiral disk is displaced, the deflection causing at least the central portion to contact the terminal pads; When the central portion contacts the terminal pads, creating a short circuit between the first side and the second side of the electrical assembly; And In response to the short circuit, causing at least a portion of the electrical assembly to fail and interrupting current flow between the first side and the second side of the electrical assembly.

2. The method according to claim 1, wherein current associated with the short circuit at least traverses the terminal pads, the spiral disk, and the lid.

3. The method according to claim 1, the method further comprising: In response to the short circuit, causing resistive heating of at least the portion of the electrical assembly until at least the portion of the electrical assembly fails.

4. The method according to claim 1, the method further comprising: In response to interrupted current between the first side and the second side of the electrical assembly, causing the battery cell to cool.

5. The method according to claim 1, wherein As a result of an electrochemical process occurring within the battery cell during an overcharge event, the pressure within the package increases.

6. The method according to claim 1, wherein the lid includes a vent disk and the package includes an internal space for receiving effluent, and the method further comprises: Activating the vent disk at a second predefined pressure threshold to release the effluent from the internal space of the package, the first predefined pressure threshold being less than the second predefined pressure threshold.

7. The method according to claim 1, wherein the battery cell further includes a terminal post that is isolated from the lid, the terminal post being electrically coupled to the terminal pads and the first side of the electrical assembly, the lid being electrically coupled to the second side of the electrical assembly, and creating the short circuit includes: When the central portion contacts the terminal pads, creating the short circuit between the first side and the second side of the electrical assembly via the terminal post, the terminal pads, and the lid.

8. The method according to claim 1, wherein causing at least a portion of the electrical assembly to fail includes: Melting the portion of the electrical assembly to interrupt the current.

9. The method according to claim 1, wherein the battery cell includes a terminal insulator disposed between the cover and the terminal pad, the terminal insulator defining an opening, and deflecting the reverse disc includes: shifting the central portion through the opening to contact the terminal pad.

10. The method according to claim 1, wherein the terminal pad is electrically connected to the first side of the power assembly, the battery cell further includes another terminal pad, the another terminal pad is electrically connected to the second side of the power assembly, in response to the pressure within the package being greater than the first predefined pressure threshold, the shifting further causes at least the central portion to contact the another terminal pad, and when the central portion contacts the terminal pad, forming a short circuit between the first side and the second side of the power assembly includes: forming the short circuit between the terminal pad and the another terminal pad; and preventing the current from flowing through the plurality of legs to the cover.

11. A method for interrupting current within a battery cell, including any technical feature or any combination of technical features in claims 1-10.

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