A terminal assembly and a venting arrangement for a secondary cell

Abstract

There is disclosed herein a venting arrangement (2000, 3000) and a terminal assembly (100, 200, 300) configured to seal an opening (534o) in a casing (534) of a cylindrical secondary cell (4000, 5000), wherein the terminal assembly (100, 200, 300) comprises a venting channel (130, 230, 330), and the venting channel (130, 230,330) is configured to vent gases generated upon a failure of the cylindrical secondary cell (4000, 5000), the venting arrangement (2000, 3000) comprising: the terminal assembly (100, 200, 300), and a failure vent (2100) arranged to block the venting channel (130, 230, 330) and configured to rupture in response to an internal pressure of the cylindrical secondary cell (4000, 5000) exceeding a threshold.

Description

A TERMINAL ASSEMBLY AND A VENTING ARRANGEMENT FOR A SECONDARY CELLTechnical Field

[0001] The present disclosure relates to a terminal assembly and a venting arrangement for a secondary cell, a secondary cell comprising the terminal assembly and / or the venting arrangement, and a battery pack comprising such a secondary cell.Background

[0002] In addressing climate change, there is an increasing demand for rechargeable batteries, e.g. to enable electrification of transportation and to supplement renewable energy. Currently, lithium-ion batteries are becoming increasingly popular. They represent a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging.

[0003] As the demand for rechargeable batteries increases, more and more focus is being placed on safety issues. To achieve safer rechargeable batteries, the design of the batteries can be optimized.

[0004] Rechargeable battery cells, particularly those used in electric vehicles (EVs), require effective venting mechanisms to ensure optimal performance and safety. The venting process is crucial for maintaining the functional safety of battery packs.

[0005] Venting of a cell may be carried out due to the temperature and pressure changes that occur within the cell enclosure. Such changes can result from weather conditions, heat from electronic circuits, changes in altitude, and / or chemical failure of the cell. Without proper venting, these changes can lead to potentially dangerous thermal runaway conditions.

[0006] Given these challenges, the integration, installation, and design of venting arrangements for battery cells are crucial for optimal battery venting and safety. Hence, further solutions aiming to improve the safety and efficiency of venting in battery cells are needed.Summary

[0007] The present disclosure aims to provide improved secondary cells and parts thereof. The improvements may be in energy performance, safety, manufacturing efficiency, decreased amount of material use, and assembly simplification, among others.

[0008] In particular, according to a first aspect of the present disclosure, there is provided a terminal assembly configured to seal an opening in a casing of a cylindrical secondary cell, comprising a head portion having a top surface configured to form an external terminal of the cylindrical secondary cell and a shaft portion configured to extend through the opening in the casing from a bottom surface of the head portion opposite the top surface. The head portion further comprises a side surface between the top surface and the bottom surface, and the terminal assembly further comprises a venting channel having an inlet at the shaft of the terminal assembly and an outlet at the side surface of the head portion. The venting channel is configured to vent gases generated upon a failure of the cylindrical secondary cell from inside the casing of the cylindrical secondary cell to an environment outside the casing of the cylindrical secondary cell.

[0009] Hereby, improved safety of cylindrical secondary cells is provided. In particular, the venting channel of the terminal assembly provides immediate pressure relief if a battery cell overheats or combusts. Thus, potential explosions and / or other hazardous outcomes that may occur due to a buildup of pressure within the battery cell may be prevented. The venting channel allows the gases produced to escape safely, thereby reducing the risk of damage or injury.

[0010] Moreover, by providing a venting channel through the terminal assembly, no additional opening or weakening in the casing of the cell may be provided. Thus, the integrity of the casing may be enhanced.

[0011] The cylindrical secondary cell may be referred to as battery cell or simply ‘cell’ throughout the present specification.

[0012] The terminal assembly may refer to a device which provides a point of electrical connection between a battery cell and an external circuit or load. The terminal assembly may be formed as a rivet and referred to as a ‘terminalrivet’. In other words, the terminal assembly may be a mechanical fastener which has a head on one end and a shaft (e.g., cylindrical) on the other end. In particular, when installed, the shaft of the terminal assembly may be deformed, to become larger than the opening in the casing through which it was arranged, thereby securing the terminal assembly in place. The shaft of the terminal assembly may be electrically connected (through attachment or abutment) to an anode or cathode current collector of the cell, thus allowing the terminal assembly to provide a secure electrical connection.

[0013] The terminal assembly may preferably be isolated from the surrounding casing by a gasket, which serves to form an electrically insulating and water-tight seal between the terminal assembly and the casing. Hence, the casing (or parts thereof) can serve as one terminal (e.g., an anode terminal) and the head of the terminal assembly can serve as the other terminal (e.g., the cathode terminal).

[0014] The terminal assembly according to aspects of the present disclosure thus has at least two functions, to provide an electrical connection point that is isolated from the surrounding casing, and to provide venting of gases generated upon failure of the battery cell. The venting feature provided by the venting channel of the terminal assembly may act as a safety vent. By allowing gases to escape in the event of overpressure within the battery cell, potential damage or rupture may be avoided. Therefore, a terminal assembly with these features may improve performance, safety, and / or durability of a battery cell.

[0015] As mentioned above, by incorporating the venting channel in the terminal assembly, manufacturing of safer battery cells is facilitated by circumventing any need of implementing venting holes and / or venting potions in the casing of the battery cell. Hereby, venting of battery cells may be provided without manufacturing special casings, which may consequently reduce costs and simplify the battery production process by allowing for greater flexibility and resource optimization.

[0016] The venting channel may serve as an indicator of a failure of a battery cell. Battery failure may occur due to over-discharging or a hard short, both of which can cause the battery cell to overheat and produce gases. Such gasesmay be vented to an environment outside the casing of the battery cell through the venting channel. The vented gases may in turn signal that the battery cell has failed. Hence, timely intervention and replacement of the battery cell may be performed, thus preventing further damage to surrounding battery cells and / or to a machine powered by the battery cell.

[0017] In some examples, the gases may interact with a current interrupt device or a fuse-type device to permanently cut off an electrical contact and / or circuit. In other words, such a device may be triggered by gases formed by excessive battery cell pressure and / or high temperature and running through the venting channel.

[0018] The outlet at the side surface of the head portion may provide directed venting to a preferred side of the head portion of the terminal assembly. The venting channel may be directed to avoid a welding region for attaching a busbar.

[0019] By venting in a defined direction, or plane, heat and / or ejecta from the battery cell may be controlled to prevent propagation of failure throughout a battery module comprising battery cells. Hence, improved safety of battery cells is provided. Moreover, if the cell is installed into an electric vehicle, the vented gases therefrom can be preferably directed away from the occupants of the vehicle, and preferably towards the ground or to an environment external to the vehicle.

[0020] According to a second aspect of the present disclosure, there is provided a venting arrangement for a cylindrical secondary cell, comprising a terminal assembly configured to seal an opening in a casing of the cylindrical secondary cell, and a failure vent arranged to block the first venting channel and configured to rupture in response to an internal pressure of the cylindrical secondary cell exceeding a threshold.

[0021] The terminal assembly comprises a head portion having a top surface configured to form an external terminal of the cylindrical secondary cell, a shaft portion configured to extend through the opening in the casing from a bottom surface of the head portion opposite the top surface, and a first venting channel through the terminal assembly.

[0022] The failure vent and the venting arrangement are configured to vent gases generated upon a failure of the cylindrical secondary cell from inside the casing of the cylindrical secondary cell to an environment outside the casing of the cylindrical secondary cell.

[0023] The second aspect may generally present the same or corresponding advantages as the first aspect. In particular, the terminal assembly of the first aspect may generally present the same or corresponding advantages as the terminal assembly and / or venting arrangement of the second aspect, and vice versa.

[0024] The failure vent of the venting arrangement may be designed to burst when an internal pressure of the battery cell rises and / or exceeds a threshold. In other words, the failure vent may be a breakable portion or constitute a notch in the material of the terminal assembly or a separate part of the venting arrangement. In yet other words, the failure vent may be a membrane, comprise a membrane, and / or may be formed from a local weakening in the terminal assembly. In particular, the failure vent may be free-floating, i.e. not connected or welded to a current collector and / or disc of the battery cell. The failure vent may be arranged at any location suitable for permitting gas flow through the venting channel if and only if a failure of the cell has occurred.

[0025] The first venting channel may comprise an inlet arranged at a shaft of the terminal assembly and an outlet arranged at a side surface of the head portion of the terminal assembly. In other examples, the outlet may be arranged on the top surface of the head portion of the terminal assembly, or elsewhere directed to an environment external to the cell. The outlet may preferably be positioned to avoid a location where a connection to the head portion is formed (e.g., a busbar connection) or the outlet may be positioned to coincide therewith as a part of some current interrupt system, as mentioned above, depending on the implementation.

[0026] Thus, gases generated inside the casing may enter the inlet and escape the casing through the outlet. The inlet may be arranged at a bottom portion of the shaft. The inlet may be arranged at the shaft at an opposite side of the head portion and / or at a furthest distance from the head portion of theterminal assembly. The inlet may specifically be arranged at a position configured to be inside the casing when the terminal assembly is installed on a battery cell. In particular the inlet may be arranged at a position where gases are expected to accumulate and / or a pressure inside the battery cell is expected to increase. Hence, gases may be facilitated to enter the inlet due to its position.

[0027] The failure vent may be arranged at the inlet. In particular, before failure of the battery cell, the failure vent may block or obstruct the inlet. Upon rupture of the failure vent, an opening to the inlet may be created. Thereby making the inlet available for gases to enter.

[0028] Alternatively, the failure vent may be arranged inside the first venting channel, the failure vent may, e.g., be arranged between the inlet and the outlet.

[0029] The outlet may be arranged at a peripheral side portion of the head portion of the terminal assembly. An opening to the outlet may, e.g., be perpendicular, or substantially perpendicular, to the opening of the inlet. In other words, the gases may enter the inlet in a direction perpendicular, or substantially perpendicular, to a direction in which the gases exit the outlet.

[0030] An angled or curved venting channel may allow for a greater surface contact with the material mass of the terminal assembly, and may further allow for solid ejecta to be retained in the venting channel. Hence, the temperature of and ejecta in the vented gases may be advantageously reduced.

[0031] The outlet may allow the gases to exit in a defined or predetermined direction. Hereby, a distribution or dissipation of heat and / or ejecta from a failing battery cell may be further controlled.

[0032] Further, a failure vent may be arranged at the outlet. In particular, before failure of the battery cell, the failure vent may block or obstruct the outlet. Upon rupture of the failure vent, an opening to the outlet may be created, thereby allowing the gases to exit through the outlet.

[0033] The terminal assembly may comprise a plurality of failure vents. The terminal assembly may, e.g., comprise a failure vent at the inlet of the venting channel and at the outlet of the venting channel. Hence, matter or particulatesmay be prevented from entering the venting channel before rupture of the failure vent. In other words, the failure vent and / or a blockage mechanism may be provided to prevent unwanted materials from entering the venting channel, thereby preventing potential clogging, and / or ensuring that when the venting channel needs to be utilized to vent gases, a clear path is available.

[0034] The head portion may be formed as a single piece, i.e., as a monolithic part (e.g., also with the shaft portion), or the head portion may comprise a cap. The cap may act as a connecting portion of the battery cell. The cap may serve as a protective layer, shielding the terminal assembly from environmental factors, and may cover a surface of the terminal assembly upon which a welding laser or the like has been directed (e.g., during welding of the terminal assembly to a current collector). Thus, the cap can provide a reliable connection surface for busbars or the like. Furthermore, the cap may provide a larger surface area, contributing to operational efficiency.

[0035] The cap may form and / or comprise a second venting channel for venting to an external environment.

[0036] The second venting channel may be integrated in, or integrally formed with, the cap. Alternatively, the second venting channel may be formed by a void space in between the (rest of the) terminal assembly and the cap.

[0037] The second venting channel may guide and / or direct the gases generated into the external environment.

[0038] The terminal assembly may comprise the cap. In particular, the terminal assembly may comprise a terminal rivet and a cap. Hence, the terminal assembly may comprise two pieces allowing for a current collector weld thereto and / or forming of a void space for venting. The cap may, e.g., be welded to the terminal assembly to provide a connection surface to the battery cell.

[0039] Concretely, example assembly steps may comprise a riveting of the terminal assembly into the opening of the casing (with a gasket arranged therearound), an arrangement of an electrode roll into the casing with a current collector between the (riveted) shaft of the terminal assembly and the electrode roll, a welding of the shaft to the current collector (from the outside of the cell), and then a welding of the cap of the terminal assembly.

[0040] The cap may be arranged in connection with the terminal assembly such that the first venting channel is in fluid communication with the second venting channel.

[0041] Hereby, the generated gases may flow seamlessly between the first venting channel and the second venting channel. The gases may be vented by entering the inlet of the first venting channel, exiting the outlet of the first venting channel to enter an inlet of the second venting channel, and exiting and / or being distributed into the external environment from an outlet of the second venting channel.

[0042] The second venting channel may extend laterally along the cap (i.e., in a radial direction).

[0043] The lateral extension of the second venting channel may provide improved directional control of the vented gases. The directional control of the gases may ensure safety and prevent backflow or misdirection of the gases.

[0044] The first venting channel may be a hollow shaft through the terminal assembly.

[0045] The hollow shaft through the terminal assembly may provide efficient dissipation of the generated gases within the casing of a battery cell by serving as a conduit for the gases. Moreover, the hollow shaft may contribute to a reduction of a weight of the terminal assembly and, consequently, battery cells.

[0046] The venting arrangement may further comprise a current collector. That is, the arrangement and configuration of the current collector may be such that gases are guided by the current collector (or at least a portion thereof) towards the venting channel. It will be appreciated that a void formed in the region of the inlet of the venting channel and / or the failure vent may be assistive in facilitating the rupture of the failure vent and the flow of gases out of the cell through the venting channel.

[0047] The current collector may be welded to the terminal assembly, e.g., as laid out above in the example assembly steps. The current collector may facilitate efficient transfer of electrical charge between the electrode roll and the terminal assembly.

[0048] The current collector may contribute to regulation of heat within the battery cell. The current collector may, e.g., distribute thermal energy more evenly to prevent overheating. The integration of a current collector within the venting arrangement may further lead to a more compact design (i.e., the failure vent may be formed in the current collector rather than as a separate part).

[0049] That is, the current collector may comprise the failure vent and / or a portion configured to rupture. In the latter case, the portion configured to rupture may be arranged to coincide with the failure vent so as to permit gas flow therethrough.

[0050] The failure vent may be integrally formed with the current collector. The failure vent may, e.g., be a membrane, a weakened portion of the current collector, and / or a notch in the material of the current collector.

[0051] The failure vent of the current collector may be arranged in connection with the inlet of the first venting channel. Thereby, upon failure of the battery cell, the failure vent may rupture and provide an opening to the inlet of the first venting channel.

[0052] By including the failure vent in the current collector, the manufacturing process may be simplified. In particular, creation of a portion configured to rupture may be facilitated on a substantially flat component such as a current collector. The failure vent being arranged on the current collector may further allow for a more compact design by not having a dedicated portion of terminal assembly comprising the failure vent.

[0053] According to a third aspect of the present disclosure, there is provided a cylindrical secondary cell comprising a terminal assembly according to the first aspect, and / or a venting arrangement according to the second aspect.

[0054] The third aspect may generally present the same or corresponding advantages as the former aspects.

[0055] According to a fourth aspect of the present disclosure, there is provided a battery pack comprising a plurality of secondary cells, wherein one or more of such secondary cells is a cylindrical secondary cell according to the third aspect.

[0056] The fourth aspect may generally present the same or corresponding advantages as the former aspects.

[0057] According to a fifth aspect of the present disclosure, there is provided a vehicle comprising a battery pack according to the fourth aspect.

[0058] The fifth aspect may generally present the same or corresponding advantages as the former aspects.

[0059] In some cases, the cylindrical secondary cell as described herein may be incorporated into a battery pack having a plurality of similar or different secondary cells. Such a battery back may further be incorporated into a vehicle, such as an electric or hybrid vehicle. Thus, the benefits provided by the above-described configuration of the terminal assembly may further benefit the battery pack or vehicle into which they are integrated, especially if a plurality of cells having such a terminal assembly are installed therein.

[0060] Hence, safer battery cells, safer battery packs, and safer electric vehicles can be realized, as well as an improved manufacturing process, leading to, e.g., reduced production costs. Furthermore, the terminal assembly and venting arrangement can facilitate easier assembly, contributing to the efficiency of the production process.Brief Description of the Drawings

[0061] One or more example implementations of the present disclosure will be described, by way of example only, and with reference to the following figures, in which:

[0062] Figure 1 A schematically shows a cross-sectional view of an example terminal assembly comprising a venting channel;

[0063] Figure 1 B schematically shows a cross-sectional view of the terminal assembly of figure 1A, extending through an opening in a casing of a cylindrical secondary cell, according to an example implementation;

[0064] Figure 2A depicts a cross-sectional view of a venting arrangement for a cylindrical secondary cell, wherein the shaft of the terminal assembly has been deformed by riveting, according to an example implementation;

[0065] Figure 2B depicts a cross-sectional view of a venting arrangement according to another example implementation;

[0066] Figures 3A and 3B schematically show example alternatives of a failure vent;

[0067] Figures 4A to 4E schematically show cross-sectional views of various examples of a terminal assembly or a venting arrangement wherein the terminal assembly comprises a cap;

[0068] Figures 5A and 5B schematically show an underside of example caps;

[0069] Figure 6 depicts a cross-sectional view of a cylindrical secondary cell comprising a terminal assembly formed as a rivet extending through an opening in the casing, according to an example implementation of the present disclosure;

[0070] Figure 7 shows a battery pack comprising a plurality of cells; and

[0071] Figure 8 shows a vehicle comprising the battery pack shown in figure 7.Detailed Description

[0072] The present disclosure is described in the following by way of a number of illustrative examples. It will be appreciated that these examples are provided for illustration and explanation only and are not intended to be limiting on the scope of the present disclosure. Instead, the scope of the present disclosure is defined by the appended claims.

[0073] Furthermore, although examples may be presented individually for the sake of focused discussion of particular features, it will be recognized that the present disclosure also encompasses combinations of the examples described herein.

[0074] Figure 1 A schematically shows a cross-sectional view of an example terminal assembly 100. The terminal assembly 100 comprises a head portion 110 having a top surface 112, and a shaft portion 120. The head portion 110 has a bottom surface 114 opposite the top surface 112, and a side surface 116 between the top surface 112 and the bottom surface 114. The head portion 110 and the shaft portion 120 may be substantially cylindrical.

[0075] Here, the terminal assembly 100 further comprises a venting channel 130 having an inlet 132 at the shaft portion 120 of the terminal assembly 100 and an outlet 134 at the side surface 116 of the head portion 110. However, the outlet 134 may be arranged at any side of the head portion 110. The outlet may, e.g., be arranged at the top surface 112 of the head portion 110.

[0076] It will be appreciated that the cross-sectional view is taken coincidentally with the venting channel 130 such that the terminal assembly 100 appears to be discontinuous, but the terminal assembly in the illustrated example is formed as a single piece and the venting channel 130 is merely a bore through an otherwise monolithic part.

[0077] In Figure 1 A, the inlet is further depicted to be arranged on a bottom surface of the shaft portion 120, more specifically, the inlet 132 is here centrally arranged at an opposite side of the top surface 112 of the head portion 110. However, the inlet 132 may be arranged at any suitable location of the shaft portion 120.

[0078] It is to be understood that terminal assembly 100 is herein depicted with a specific shape to aid understanding of the present disclosure.However, the shape of the terminal assembly 100 may vary depending on specific requirements of a device it is configured to be used in. Portions of the terminal assembly 100, or the terminal assembly 110 itself, may be rectangular, circular, semi-circular, or take any other shape that suits its purpose. It is further understood that the effects and advantages of the terminal assembly according to the present disclosure may be achieved regardless of its physical form.

[0079] Figure 1 B schematically shows a cross-sectional view of the terminal assembly of figure 1A, extending through an opening 434o in a casing 434 of a cylindrical secondary cell 4000 (referenced but not shown in its entirety, and also referred to as simply the ‘cell 4000’ or the ‘battery cell 4000’), according to an example implementation. The terminal assembly 100 seals the opening 434o in the casing 434 of the cylindrical secondary cell 4000. In particular, the shaft portion 120 here extends through the opening 434o in the casing 434 from the bottom surface 114 of the head portion 110 opposite the top surface

[0080] The venting channel 130 is configured to vent gases generated upon a failure of the cylindrical secondary cell 4000 from inside the casing 434 of the cylindrical secondary cell 4000 to an environment 434e outside the casing 434 of the cylindrical secondary cell 4000.

[0081] The terminal assembly 100 serves as an external terminal of the cell 4000, this being a positive terminal in this example, and the casing 434 serves as a negative terminal. Hence, it is seen that both terminals of the cell 4000 are accessible at the same side. The top end 434t of the casing 434 comprises a first electrical contact surface extending in a first plane, and the head portion 110 of the terminal assembly 100 comprises a second electrical contact surface, extending in a second plane axially spaced from the first plane.

[0082] Arranged around the terminal assembly 100 is a gasket 442 configured to form a fluid-tight seal for the opening 434o in the top end 434t of the casing 434. The gasket 442 is arranged at least around the shaft portion 120 of the terminal assembly 100. The gasket 442 further extends between the head portion 110 of the terminal assembly 100 and the top end 434t of the casing 434 so as to electrically isolate the opposite terminals of the cell 4000 from each other. Thus, it can be seen that gasket 442 serves multiple purposes. The gasket 442 may be preferably formed of a polymer having elastic, resilient, and electrically insulating properties. In preferred examples, including that illustrated in Figure 1 B, the gasket 442 extends between the terminal assembly 100 and the casing 434, radially beyond the head portion 110 of terminal assembly 100.

[0083] Figure 2A depicts a cross-sectional view of a venting arrangement 2000 for a cylindrical secondary cell 5000, wherein the shaft 220 of the terminal assembly 200 has been deformed by riveting, according to an example implementation. The venting arrangement is further arranged with a current collector 536, and cathode tabs 532a extending from an electrode roll 532 housed in a casing 534.

[0084] The electrode roll 532 may be formed of an anode sheet, a cathode sheet, and a separator sheet arranged therebetween to thereby enable a storage of electrical energy. The cathode tab 532a may extend from a firstend of the electrode roll 532 and an anode tab may extend from the other end, or vice versa. The cathode tab 532a and anode tab may provide connective surfaces to which the current collector 536 can be connected.

[0085] The venting arrangement 2000 comprises a terminal assembly 200 sealing an opening 534o in a casing 534 of a cylindrical secondary cell 5000. In turn, the terminal assembly 200 comprises a head portion 210 having a top surface 212 forming an external terminal of the cylindrical secondary cell 5000, a shaft portion 220 extending through the opening 534o in the casing 534 from a bottom surface 214 of the head portion 210 opposite the top surface 212, and a first venting channel 230 through the terminal assembly 200. The venting arrangement 2000 further comprises a failure vent 2100 arranged to block the first venting channel 230 and configured to rupture in response to an internal pressure of the cylindrical secondary cell 5000 exceeding a threshold. The failure vent 2100 and the venting arrangement 2000 are configured to vent gases generated upon a failure of the cylindrical secondary cell 5000 from inside the casing 534 of the cylindrical secondary cell to an environment 534e outside the casing 534 of the cylindrical secondary cell. A direction of gas flow through the venting channel is indicated by dashed arrows.

[0086] The failure vent 2100 is illustrated to be comprised by the current collector 536. In particular, the current collector 536 here comprises the failure vent 2100 and / or a portion configured to rupture. However, as will be explained in relation to Figures 3A and 3B, it should be understood that the failure vent 2100 may be equivalently constituted by another element or component of the venting arrangement 2000 and / or cell 5000, e.g., by the terminal assembly 200.

[0087] The first venting channel 230 comprises an inlet 232 arranged at a shaft 220 of the terminal assembly 200 and an outlet 234 arranged at a side surface of the head portion 210 of the terminal assembly 200. Here, the outlet 234 of the venting channel 230 is arranged at the side surface 216 between the top surface 212 and the bottom surface 214 of the head portion 210.

[0088] Further, in Figure 2A, the first venting channel 230 is a hollow shaft, such as an L-shaped or right-angle shaft, through the terminal assembly 200.However, the first venting channel 230 may take any suitable shape, the first venting channel 230 may, e.g., form a straight or bent conduit through the terminal assembly 200. The path of the first venting channel 230 may be designed to bend gradually, e.g., to accommodate spatial constraints of the terminal assembly or to facilitate efficient flow of gases. The gradual bending may further minimize turbulence and / or pressure drop of the gas flowing through the first venting channel 230. The bend could be a curve, a spiral, or any other suitable shape.

[0089] The illustration of the current collector 536, the cathode tabs 532a, and the electrode roll 532 is purely schematic. It will be appreciated that, in preferred arrangements, a void or space is formed in the vicinity of the failure vent 2100 and venting channel 232.

[0090] A cross-sectional shape or profile of the first venting channel 230, looking across a width thereof, may be circular, square, rectangular, or any suitable cross-sectional shape, such as a hexagon or an ellipse.

[0091] Furthermore, although not shown, the cross-sectional shape or width of the first venting channel 230 may change along its length, e.g., transitioning from one shape to another to accommodate changes in flow conditions. For example, the first venting channel 230 may start with a circular cross-section at the inlet 232 and transition to a square cross-section at the outlet 234. Thus, heat transfer may be improved or gases may be distributed as desired into the environment 534e outside the casing 534.

[0092] Figure 2B depicts a cross-sectional view of a venting arrangement 2000 according to another example implementation. Figure 2B benefits from the same description as Figure 2A. However, here, the outlet 234 of the venting channel 230 is arranged at a top surface 212 of the head portion 210 of the terminal assembly 200.

[0093] The venting arrangement 2000 of Figure 2B further illustrates a busbar 2200 welded to the top surface 212 of the head portion 210 of the terminal assembly 200. The busbar 2200 is welded to a pre-treated surface 2210 of the terminal assembly 200. The pre-treated surface 2210 may enable a more reliable connection of the busbar 2200 thereto.

[0094] The outlet 234 of the venting channel 230 is specifically positioned to avoid interference with the busbar 2200. In other words, the venting channel 230 is located in the terminal assembly 200 such as to prevent any disruption with the busbar 2200. Thus, the venting channel 230 is here displaced or offset from a center axis of the terminal assembly 200.

[0095] Figures 3A and 3B schematically show example alternatives of a failure vent 2100. The failure vent 2100 may be the failure vent 2100 of the venting arrangement 2000 according to any one of Figures 2A to 2B.

[0096] In Figure 3A, a current collector 536 comprises the failure vent 2100 of a venting arrangement 2000. Here, the failure vent 2100 is formed by a notch 2110 in the material of the current collector 536. However, the failure vent 2100 may alternatively be a membrane or a weakened portion of the current collector 536.

[0097] The failure vent 2100 is aligned with an inlet 232 of a venting channel 230 of a terminal assembly 200 of the venting arrangement 2000. A ruptured failure vent 2101 is further depicted as a dotted shape. The ruptured failure vent 2101 may, e.g., be a broken membrane or a broken portion of the current collector 536.

[0098] In Figure 3B, the terminal assembly 200 comprises the failure vent 2100. Here, the failure vent 2100 is formed by a notch 2110 in the material of the terminal assembly 200. However, the failure vent 2100 may alternatively be a membrane or a weakened portion of the terminal assembly 200.

[0099] The failure vent 2100 is arranged at the inlet 232 of the venting channel 230 of the terminal assembly 200. Alternatively, or additionally, the failure vent 2100 may be located at an outlet of the venting channel 230.

[0100] A ruptured failure vent 2101 is depicted as a dotted shape. The ruptured failure vent 2101 may, e.g., be a broken membrane or a broken portion of the terminal assembly 200.

[0101] Figures 4A to 4E schematically show cross-sectional views of various examples of a terminal assembly 300 or a venting arrangement 3000 wherein the terminal assembly 300 comprises a cap 350. The venting arrangement 3000 may be the venting arrangement 3000 according to any of Figures 2A to2B and the terminal assembly 300 may be the terminal assembly 300 according to any one of Figures 1A-B and 2A-B.

[0102] In Figures 4A-E a head portion 310 of the terminal assembly 300 comprises the cap 350. The cap 350 may, e.g., be welded to the head portion 310 of the terminal assembly 300. More specifically, the cap 350 is here attached to a top surface 312 of the head portion 310 of the terminal assembly 300.

[0103] In Figures 4A-B, the cap 350 forms a second venting channel 340 for venting to an external environment. In particular, the cap 350 is arranged in connection with the terminal assembly 300 such that the first venting channel 330 is in fluid communication with the second venting channel 340.

[0104] Figure 4A schematically shows an alternative where the second venting channel 340 is formed by an indentation or depression in the top surface 312 of the head portion 310, which may be referred to as a top surface recess. The cap 350 aligns and / or covers the top surface recess when brought together with the terminal assembly 300. The surface of the cap 350 may be substantially flat, allowing for a seamless interface between the cap 350 and a substantially flat portion of the terminal assembly 300. Alternatively, the cap 350 and head portion 310 of the terminal assembly 300 may take any suitable forms such that they interlock or complement each other as to form a cohesive unit.

[0105] The cap 350 being arranged on the top surface 312 hereby forms a space enclosed by the top surface recess and the cap 350, thereby forming the second venting channel 340.

[0106] Similarly, in Figure 4B, the cap 350 comprises a recess forming the second venting channel 340.

[0107] In Figures 4C-D, the cap 350 comprises the second venting channel 340. In particular, Figure 4C shows a disassembled terminal assembly 300 and / or venting arrangement 3000, while Figure 4D shows an assembled version. Figures 4C-D illustrate the second venting channel 340 as an L-shaft or right-angle shaft through the cap 350. However, it is understood that the second venting channel 340 may take any suitable shape.

[0108] Further, Figures 4C-D schematically illustrates an alternative where the terminal assembly 300 has a head portion 310 with a shape configured receive and / or interlock the cap 350. In particular, the head portion 310 and top surface 312 are here formed as to fit the cap 350 at least partially therein.

[0109] Throughout Figures 4A-D, the second venting channel 340 extends substantially laterally along the cap 350. However, it is understood that the second venting channel 340 may take any suitable path through or along the cap 350.

[0110] Moreover, the shape, size, cross-section, orientation, and general description of the second venting channel 340 benefits from the same description as the first venting channel 330. In particular, the first venting channel 330 may have a first cross-sectional area while the second venting channel 340 may have a second cross-sectional area. Similarly, one channel may have a circular cross-section, while the other may have a square or rectangular cross-section to, e.g., achieve certain flow characteristics. The point where the first and second venting channels 330, 340 connect may involve a gradual change in cross-sectional shape or size, or a connector or adapter may join the first and second venting channels 330, 340.

[0111] Figure 4E illustrates an alternative where the first venting channel 330 is smaller at the inlet 332 and then expands to a void space within the terminal assembly. Further, the cap 350 here forms a larger second venting channel 340 within the cap 350 which exits to the external environment through a smaller opening of the terminal assembly 300.

[0112] The terminal assembly 300 is further illustrated to be welded to a current collector 3036 at welding points 302a-b. In particular, the terminal assembly 300 here comprises two pieces to allow for ease of welding of the terminal assembly 300 to the current collector 3036 and for forming of the void space constituting the first and second venting channels 330, 340.

[0113] The welding points 302a-b may refer to a welding area or a welding portion. In particular, the welding may, e.g., be performed by arc welding or laser welding.

[0114] Figures 5A and 5B schematically show an underside of example caps 350. Alternatively, Figure 5A and 5B may schematically illustrate a cross-sectional top-view of a cap 350, or the head portion 310 of a terminal assembly 300.

[0115] In Figure 5A, a single venting channel 340 is illustrated to extend radially through the cap 350. The venting channel 340 originates at an essentially center of the cap 350 and extends towards the periphery, following a straight path.

[0116] In Figure 5B, four distinct venting channels 340 are illustrated to extend radially through the cap 350. Each venting channel 340 originate from an essentially center of the cap 350 and extend towards the periphery, each venting cannel 340 following a straight path. The cap 350 shown in figure 5B may correspond to that shown in figure 4E.

[0117] Figure 6 schematically shows a cross-sectional view of a cylindrical secondary cell 6000 comprising a venting arrangement and / or a terminal assembly 600 formed as a rivet 600 extending through an opening 634o in the casing 634, corresponding to the example venting arrangement according to Figures 2A-B or 4A-D and / or terminal assembly 600 as shown and discussed in relation to e.g. Figures 1A-B. The particulars of the venting arrangement and the terminal assembly 600 are thus not discussed again in relation to Figure 6.

[0118] The cylindrical secondary cell 6000 (also referred to as simply the ‘cell 6000’) comprises an electrode roll 632 housed in a cylindrical casing 634. The electrode roll 632 may be formed of an anode sheet, a cathode sheet, and a separator sheet arranged therebetween to thereby enable a storage of electrical energy. Cathode tabs 632a may extend from a first end of the electrode roll 632 and anode tabs 632b may extend from the other end, or vice versa. The cathode tabs 632a and anode tabs may provide connective surfaces to which current collecting plates 636 can be connected.

[0119] The cylindrical casing 634 extends along an axis between a first end 634t, which may be referred to as a ‘top end 634t’, and a bottom end (not shown) which may be an open end of the casing 634 closed by a lid. The closure of the casing may comprise a clamped closure or a welded closure, depending on the implementation.

[0120] For example, the casing 634 may further comprise a beading groove (not shown) formed in the side wall 634s. Hence, between the beading groove and the end edge of the side wall towards the bottom end of the casing 634, a clamping portion can be formed. A lid gasket may then be clamped around the bottom lid in the clamping portion to thereby seal the open bottom end of the casing 634. Providing a clamped closure in this way is well known in the art and thus can provide a reliable waterproof seal for the cell 6000.

[0121] As another example, the lid may be welded to the casing 634 to thereby seal the casing 634. The lid may be additionally welded to a current collector, or the lid may act as a current collector itself and be attached (e.g., welded) to the tabs of the electrode assembly 632. Providing a welded closure in this way may advantageously remove the number of components of the cell 6000 and / or the number of process steps required to manufacture the cell 6000.

[0122] A cathode current collecting plate 636 is arranged in direct electrical contact with the cathode tabs 632a and an anode current collecting plate (not shown) may be arranged in direct electrical contact with the anode tabs (also not shown). Here, the labels ‘cathode’ and ‘anode’ may be swapped. Thus, an electrical connection is formed from the cathode tabs 632a to the terminal assembly 600, as the terminal assembly 600 is connected to the current collecting plate 636.

[0123] An electrical connection may also be formed from the anode tabs to the casing 634, either directly or through connection of an anode current collecting plate to the casing 634, e.g. in the clamping portion or by welding. One or both of the current collectors may be formed as a disc, a plate, or have some other shape.

[0124] At either end of the cell 6000, the cell 6000 may further comprise an additional vent for venting gases, for example during a failure of the cell, a plurality of vents may be utilized. Moreover, the cell 6000 may comprise an additional through-hole, in the casing 634 and / or the lid, for filling the cell 6000 with a liquid electrolyte. This through-hole is preferably adapted to be closed from the outside, such as through the use of a blind rivet.

[0125] The advantageous configuration of the terminal assembly 600 provides an overall safer battery cell 6000 and an overall simplified manufacturing process of safer battery cells 6000.

[0126] Figure 7 shows a perspective view of a battery pack 800 with a portion of its casing (being illustrated in a purely schematic way) cut away to schematically show a plurality of secondary cells 810 housed therein. The secondary cells 810 may correspond to the secondary cells described above.

[0127] The secondary cells 810 are connected together in series and / or parallel, and in an optionally modular fashion, so as to form a combined electrical storage capacity. In some examples, the cells have a common orientation such that failure vents of the cells are oriented in a same direction, and such that the terminals of the cells (which may be on the same side, as discussed above) can be accessed at a same side. Similarly, the venting may be advantageously directed to a same side, as discussed above.

[0128] Figure 8 schematically shows an example vehicle 900 comprising the battery pack 800 shown in figure 7. In this example, the battery pack is arranged at a lower portion of the vehicle 900, which may be an electric or hybrid vehicle. Other uses for the battery pack 800 may comprise a standalone battery pack for powering devices or installations or the like.

[0129] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments are shown and described above by way of example in relation to the drawings, with a view to clearly explaining the various advantageous aspects of the present disclosure. It should be understood, however, that the detailed description herein and the drawings attached hereto are not intended to limit the disclosure to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the following claims.

Claims

C L A I M S1. A terminal assembly (100) configured to seal an opening (434o) in a casing (434) of a cylindrical secondary cell (4000), comprising: a head portion (110) having a top surface (112) configured to form an external terminal of the cylindrical secondary cell (4000); and a shaft portion (120) configured to extend through the opening (434o) in the casing (434) from a bottom surface (114) of the head portion (110) opposite the top surface (112); wherein the head portion (110) further comprises a side surface (116) between the top surface (112) and the bottom surface (114); wherein the terminal assembly (100) further comprises a venting channel (130) having an inlet (132) at the shaft portion (120) of the terminal assembly (100) and an outlet (134) at the side surface (116) of the head portion (110); and wherein the venting channel (130) is configured to vent gases generated upon a failure of the cylindrical secondary cell (4000) from inside the casing (434) of the cylindrical secondary cell (4000) to an environment (434e) outside the casing (434) of the cylindrical secondary cell (4000).

2. A venting arrangement (2000, 3000) for a cylindrical secondary cell (5000), comprising:a terminal assembly (200, 300) configured to seal an opening (534o) in a casing (534) of the cylindrical secondary cell (5000), the terminal assembly(200, 300) comprising: a head portion (210, 310) having a top surface (212, 312) configured to form an external terminal of the cylindrical secondary cell (5000), a shaft portion (220) configured to extend through the opening (534o) in the casing (534) from a bottom surface (214) of the head portion (210) opposite the top surface (212), and a first venting channel (230, 330) through the terminal assembly (200, 300); and a failure vent (2100) arranged to block the first venting channel (230, 330) and configured to rupture in response to an internal pressure of the cylindrical secondary cell (5000) exceeding a threshold; wherein the failure vent (2100) and the venting arrangement (2000) are configured to vent gases generated upon a failure of the cylindrical secondary cell (5000) from inside the casing (534) of the cylindrical secondary cell (5000) to an environment (534e) outside the casing (534) of the cylindrical secondary cell (5000).

3. The venting arrangement (2000) according to claim 2, wherein the first venting channel (230) comprises an inlet (232) arranged at a shaft of the terminal assembly (200) and an outlet (234) arranged at a side surface (216) of the head portion (210) of the terminal assembly (200).

4. A venting arrangement (2000, 3000) according to claim 2 or claim 3, wherein the head portion (210, 310) comprises a cap (350).

5. A venting arrangement (2000, 3000) according to claim 4, wherein the cap (350) forms and / or comprises a second venting channel (340) for venting to an external environment (534e).

6. A venting arrangement (2000, 3000) according to claim 4 or 5, wherein the cap (350) is arranged in connection with the terminal assembly (200, 300) such that the first venting channel (230, 330) is in fluid communication with the second venting channel (340).

7. A venting arrangement (2000, 3000) according to claim 5 or 6, wherein the second venting channel (340) extends laterally along the cap (350).

8. A venting arrangement (2000, 3000) according to any of claims 2 to 7, wherein the first venting channel (230, 330) is a hollow shaft through the terminal assembly (200, 300).

9. A venting arrangement (2000, 3000) according to any of claims 2 to 7, further comprising a current collector (536, 3036).

10. A venting arrangement (2000, 3000) according to claim 9, wherein the current collector (536, 3036) comprises the failure vent (2100) and / or a portion configured to rupture.

11. A cylindrical secondary cell (4000, 5000) comprising a terminal assembly (100) according to claim 1, and / or a venting arrangement (2000, 3000) according to any of claims 2 to 10.

12. A battery pack (800) comprising a plurality of secondary cells (810), wherein one or more of such secondary cells (810) is a cylindrical secondary cell (4000, 5000) according to claim 11 .

13. A vehicle (900) comprising the battery pack (800) of claim 12.

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