ELECTRICAL BRIDGE DEVICE FOR BRIDGING AN ELECTRICAL POWER SOURCE OR ENERGY CONSUMER

Description

Technical application area

[0001] The present invention relates to an electrical bridging device comprising at least two electrically insulated electrical conductors which can be electrically connected to each other by triggering an exothermic reaction in a reactive layer arranged above the conductors.

[0002] Such an electrical bridging device serves primarily to bridge a power source or energy consumer. These energy sources or consumers are found in a variety of devices, for example, in electric vehicles or stationary energy storage systems. The electrical energy can be stored in chemical form, as in the case of battery cells, or in physical form, for example, in capacitor cells. To generate sufficient voltages and high currents of 100 to 1000 A, as required, for example, for electric vehicles, several of these cells, e.g., between 4 and more than 100 cells, are connected in series to form a cell stack. A challenge with cells connected in series or parallel is ensuring the reliability of the entire stack and reorganizing the stack in the event of a cell failure.Without further measures, if one cell in a battery pack fails, the entire system will fail, even if the pack itself still contains a sufficient number of intact cells. Therefore, when using such a system in an electric vehicle, and also in most hybrid vehicles, a single cell failure can lead to system failure. Furthermore, a degraded battery cell can also exhibit increased internal resistance, which can then lead to excessive heating of the cell. It is therefore generally desirable to be able to electrically bypass defective cells during operation of the energy storage system to avoid such problems. State of the art

[0003] To solve the problem described above, so-called inverse fuses (antifuses) are known, which electrically bypass the corresponding cell or load in the event of a failure. These inverse fuses are primarily used in low-power systems, such as integrated circuits and lighting systems. One example is a fuse with a thin barrier of non-conductive amorphous silicon between two metal contacts. When a sufficiently high voltage is applied to the amorphous silicon across the two contacts, it transforms into a conductive, polycrystalline silicon-metal alloy with low resistance. In lighting systems, such an inverse fuse prevents the entire series circuit from failing if a single light bulb malfunctions. The lights themselves are equipped with this type of fuse.If one light fails, the entire mains voltage is applied to the single, failed light. This activates the fuse and electrically bypasses the failed light, allowing the series circuit to continue functioning.

[0004] Furthermore, it is known, for example in the field of photovoltaics, to bridge energy sources or energy consumers using bypass diodes. Bypass diodes serve to handle short-term interruptions in energy generation by a cell, for example in the case of shading of a solar generator cell. However, bypass diodes only establish a unidirectional connection, so an energy storage system with bypass diodes would only function reliably when energy is being discharged. Recharging the remaining intact cells would not be possible, as the diode would block current in the reverse direction. Therefore, bypass diodes, as known from the field of photovoltaics, do not represent a practical bridging solution for the applications mentioned above.

[0005] German patent DE 37 21 754 A1 discloses a bridging device for protecting battery cells, which enables the irreversible bridging of high-resistance failures in damaged memory cells. The bridging device consists of two semiconductor components arranged in series in layers, each with a different current / voltage characteristic. In the event of a high-resistance failure in a damaged memory cell, the high charging current flows through the two semiconductor components, which, due to the resulting significant temperature increase, alloy and thus irreversibly short-circuit the memory cell to a low resistance. However, such a passive bridging device is only triggered if the battery cell is already severely degraded. Premature triggering, for example to prevent high power losses, is not possible.

[0006] The inverse fuses described so far are unsuitable for use in the applications mentioned at the beginning, e.g., in batteries providing power for an electric drive. This is primarily due to the high resistance of these fuses when tripped, which leads to power losses of up to 50 W and thus to unacceptable heating of the fuses, their low current-carrying capacity, and their high cost.

[0007] German patent application DE 10 2012 005 979 A1 describes an electrical bridging element for bridging defective storage cells in energy storage devices, which is also suitable in principle for high-power batteries. In this bridging element, a sequence of layers is formed between two electrical conductors, comprising at least one electrical insulating layer and one or more reactive layer stacks in which an exothermic reaction can be triggered. The reactive layer stacks and the insulating layer are designed to work together such that the insulating layer dissolves due to the heat energy released during the exothermic reaction, thus establishing an electrical connection between the electrical conductors. However, residues from the insulating material can cause problems with this bridging element.

[0008] The object of the present invention is to provide an electrical bridging device, in particular for bridging electrical energy sources or energy consumers, which in the triggered state can carry high currents with simultaneously low series resistance, enables permanent irreversible bridging and can be manufactured cost-effectively. Description of the invention

[0009] The problem is solved by the electrical bridging device according to claim 1. Advantageous embodiments of the bridging device are the subject of the dependent claims or can be found in the following description and the exemplary embodiments.

[0010] The proposed electrical bridging device comprises at least two electrically insulated conductors, which, when used, are connected, for example, to the two poles of a power source or consumer device to be bridged. The two conductors are arranged such that at least one surface area of ​​the first conductor, oriented in a specific spatial direction, is separated by a gap from at least one surface area of ​​the second conductor, also oriented in the same spatial direction. The orientation of a surface area in a specific spatial direction means that the surface area is recognizable as a flat surface from that spatial direction. This clarifies, in particular, that the two surface areas are neither oriented towards each other nor at a perpendicular angle to each other.A bridging element with at least one electrically conductive layer is arranged across the two surface areas. This bridging element is designed as a mechanical energy storage device or is connected to a mechanical energy storage device that can be transitioned from a first mechanical state to a stable second mechanical state by thermal activation. A mechanical energy storage device can be, for example, a prestressed mechanical element or an element that exhibits at least two different stable mechanical states, such as an actuator made of a shape-memory alloy or a bimetallic element. The mechanical energy storage device is designed and arranged such that, in the stable second mechanical state of the mechanical energy storage device, the electrically conductive layer of the bridging element electrically contacts the surface areas of the two electrical conductors, thereby short-circuiting them.Furthermore, a reactive element is arranged over the surface areas, for example as an additional layer of the bridging element or as a separate element, in which an exothermic reaction can be triggered, causing the mechanical energy storage device to transition to the second mechanical state. In the untriggered state of the bridging device, the mechanical energy storage device is in the first mechanical state, in which the electrical conductors are not short-circuited by the electrically conductive layer of the bridging element. The reactive element can be designed as a reactive layer that is part of the bridging element. If designed as a separate element, the reactive element preferably lies adjacent to the bridging element but is not metallurgically bonded to it.

[0011] In this patent application, the term "reactive layer" or "reactive element" refers to a layer or film made of a reactive material, which may also be configured as a continuous sequence of layers made of different materials, i.e., as a layer stack. To trigger the bridging device, it is only necessary to initiate the exothermic reaction in the reactive layer or element. The resulting heat energy converts the mechanical energy storage device into a second mechanical state, in which the electrically conductive layer of the bridging element electrically contacts and thus short-circuits the two electrical conductors. Since this second mechanical state is stable, the mechanical energy storage device remains in this state even without further heat input.

[0012] The initiation of the exothermic reaction in the reactive element can be achieved—depending on the type of reactive material—by means of, for example, electric current, heating, sparking, laser irradiation, or an initiator. An example of a reactive element is a reactive nanofilm, such as a reactive Ni / Al film, as described in WO 01 / 83182 A1. Such nanofilms consist of a large number of nanolayers, for example, with layer thicknesses ranging from 1 nm to 500 nm, typically alternating layers of two different materials that react exothermically with each other upon appropriate energy input. Other reactive layers can also be used in the proposed bridging device, such as layers of nanothermite or other exothermically reacting materials.

[0013] The proposed bridging device allows for the low-resistance electrical bridging of an energy source, such as a battery cell, or an electrical load as the component to be bridged by triggering the exothermic reaction. In the triggered state, a resistance of less than 100 µΩ can be achieved with an active area (area under the reactive layer) of approximately 1 cm². In the untriggered state, the bridging device can exhibit a resistance greater than 40 MΩ, depending on its design. The proposed bridging device thus also enables the flow of high currents, as can occur in the applications mentioned above, and can be implemented cost-effectively due to its simple construction.

[0014] In a preferred embodiment of the proposed bridging device, the irreversible electrical contact between the two electrical conductors is facilitated by the formation of a solder joint. In a first advantageous embodiment, the first and second surface areas are each covered with a layer of an electrically conductive material that has a lower melting point than the material of the electrical conductors. Preferably, this is a metallic solder material. In principle, however, other materials are also possible, e.g., electrically conductive polymer materials.The reactive element is dimensioned and arranged on the bridging element in such a way that the two layers of electrically conductive material melt due to the heat energy released during the exothermic reaction of the reactive layer, thereby creating a solder connection with the electrically conductive layer of the bridging element, which rests on the surface areas or the solder layers applied to them in the triggered state of the bridging device.

[0015] In a second advantageous embodiment, the bridging element is covered on a side facing the surface areas with a layer of an electrically conductive material that has a lower melting point than the electrical conductors. This is preferably a metallic solder material, but can also be another material, such as an electrically conductive polymer. This layer can be an additional layer formed on the bridging element in addition to an electrically conductive layer and, if applicable, the reactive layer. This layer can also be the only electrically conductive layer of the bridging element. The reactive layer, orThe reactive element is dimensioned and arranged such that the electrically conductive material melts due to the heat energy released during the exothermic reaction of the reactive layer, thereby forming a soldered connection with the electrical conductors on which the bridging element rests when the bridging device is triggered. A combination of the first and second advantageous embodiments is also possible, in which case both surface areas of the electrical conductors and the side of the bridging element opposite these surface areas have a corresponding layer of an electrically conductive material suitable for forming a soldered connection.

[0016] Both the electrical insulation between the two electrical conductors and the insulation of at least one of the surface areas from the bridging element are selected to suit the specific application. The insulation between the two electrical conductors can be achieved via an air gap or by using an insulating material between them.

[0017] The two electrical conductors are preferably structured such that the longest possible boundary line is created between the surface areas of these conductors to be bridged. In a preferred embodiment, the first surface area (of the first conductor) surrounds the second surface area (of the second conductor). The bridging element is preferably designed to cover the second surface area, the gap between the two surface areas, and at least a portion of the first surface area.

[0018] In an advantageous embodiment, the bridging element itself is designed as a mechanical energy storage device. For this purpose, the bridging element preferably comprises a layered composite of at least two materials with different thermal expansion coefficients, which can assume two stable bending states as the first and second mechanical states. Preferably, this layered composite is a bimetallic layer. In the present patent application, the term "layer" also includes self-supporting, i.e., plate-shaped elements, so that the layered composite described above can also be a bimetallic plate. The bimetallic layer simultaneously constitutes an electrically conductive layer of the bridging element.When this design is combined with an arrangement of the electrical conductors in which the first surface area surrounds the second surface area, the bridging element is preferably dome-shaped over the surface areas in the non-triggered state (first mechanical state). When the bridging element is triggered, it then bulges downwards and establishes the electrically conductive connection between the two electrical conductors.

[0019] In other advantageous embodiments of the proposed bridging device, the mechanical energy storage device is designed separately from the bridging element and connected to it. In the unactivated state of the bridging device, in which it is in the first mechanical state, the mechanical energy storage device is prevented from transitioning from the first to the second mechanical state by a retaining force of the reactive element. Preferably, the mechanical energy storage device is an elastic element, for example, a spring element, which is held in a pre-tensioned state as the first mechanical state by the reactive element.When the exothermic reaction is triggered, the reactive element is destroyed or at least loses its holding force, allowing the mechanical energy storage device to transition to its second mechanical state. In this state, the bridging element presses against the two surface areas. To generate the holding force, the reactive element must rest appropriately on one or more spacers, preferably arranged around the area to be electrically contacted. These spacers could, for example, be a suitable frame. The other components of the bridging element are designed so that they do not rest on these spacers or the frame. This configuration requires a reactive element capable of exerting a suitable holding force. This is particularly true for the reactive nanofilms mentioned earlier, which offer sufficient holding forces but lose them when the exothermic reaction is triggered.

[0020] The exothermic reaction can be triggered, for example, thermally by an electric current flowing through the reactive element. The reactive element can be contacted, for instance, via one or more contact pins to apply an electrical voltage. Alternatively, a suitable structure can be used to create a constriction within the reactive element, where the increased resistance during current flow generates heat. The reactive element can also be activated optically, for example, by a light or laser pulse. In another embodiment, an initiator can be used, such as a reactive wire, which is in contact with or at least near the reactive element. Such a reactive wire also consists of a reactive material, for example, a layer sequence of aluminum and palladium, and can be triggered thermally by an electric current.Such reactive wires are also commercially available, for example under the name Pyrofuze®. Triggering the reactive layer by electrical sparks is also possible. This is, of course, not an exhaustive list.

[0021] The proposed bypass device provides an irreversibly activatable, low-resistance electrical connection. This allows a faulty component in a current path to be bypassed, thus ensuring the functionality of the overall system. Examples include bypassing defective components and assemblies, particularly energy storage devices such as battery cells, accumulators, double-layer capacitors, lithium-ion batteries, or capacitors, as well as fuel cells or electrical loads. Furthermore, the proposed bypass device can be used to deactivate energy storage devices such as lithium-ion battery cells by triggering a fuse or a shutdown separator with short-term short-circuit currents in the 10 kA range. Brief description of the drawings

[0022] The proposed bridging device is explained in more detail below using two exemplary embodiments. These show: Fig. 1 a sectional view of a first example of a bridging device in the non-triggered state; Fig. 2 the example of the Figure 1 in the triggered state; Fig. 3 a sectional view of a second example of the proposed bridging device in the untriggered state; and Fig. 4 the example of the Figure 3 in the triggered state. Ways to implement the invention

[0023] Figure 1Figure 1 shows a first example of an embodiment of the proposed bridging device. The bridging device has two electrodes 1, 2 that are insulated from each other. The electrodes are structured such that the longest possible boundary line is created between their surface areas, which are located close to each other on the upper side. In this case, this is achieved by a rotationally symmetrical structure in which the surface area of ​​the first electrode 1 completely surrounds the surface area of ​​the second electrode 2 in a ring-like fashion. Electrical insulating material 5, which also acts as a spacer, is located between the two electrodes 1, 2. A solder layer 9, 10 is applied to each of the adjacent surface areas of the two electrodes 1, 2.A bridging element 3 is arranged over the surface areas, comprising at least one electrically conductive layer 6 with which the two electrodes 1, 2 can be electrically connected. In the present example, this bridging element 3 consists of a bimetallic element 7 comprising two bimetallic layers, a reactive layer 4, and a solder layer 11. Both the solder layer 11 and the bimetallic element 7 can be considered electrically conductive layers 6. The bimetallic element 7 is shaped such that it can assume two stable mechanical states and thus represents a bistable mechanical energy storage device. Figure 1 This shows the first stable mechanical state in which the bridging element 3 with the bimetallic element 7 is curved upwards and thus does not establish an electrical connection between the two electrodes 1, 2.

[0024] To activate the bridging device, the exothermic reaction in the reactive layer 4 is triggered. The resulting heating causes the bimetallic element 7 to transition into its more stable second geometric or mechanical state, in which it is curved downwards and thus electrically connects the two electrodes 1, 2 via the solder layers 9, 10, 11, which fuse together due to the thermal energy generated during the exothermic reaction.

[0025] The bridging element 3 is arranged such that a minimum distance is maintained between the solder layer 11 on the bridging element and the solder layer 10 of the second electrode 2 in order to maintain the insulation between the two electrodes 1, 2 when the bridging device is not triggered. The bridging element 3 rests on the outer electrode 1, as shown in the figure. However, the bridging element 3 can also be arranged insulated from the first electrode 1, thus enabling a galvanically isolated triggering from the switched current path. In this example, the bridging element 3 is preferably dome-shaped or approximately dome-shaped over the two surface areas and arranged so that the reaction chamber is closed to the outside.

[0026] This bridging device is in principle suitable for both low voltages (e.g., battery cells with a few volts) and higher voltages (e.g., battery modules, battery packs, and fuel cells with several hundred volts). However, due to the limited deflection of the bimetallic element 7 and the associated limitation of the maximum distance to the electrodes, the dielectric strength of such a design is limited.

[0027] In principle, either the solder layer 11 on the bridging element 3 or the solder layers 10, 11 on the surface areas of the electrodes 1 can be omitted, since the electrical connection can also be established solely through the solder layer 11 on the bridging element 3 or through the solder layers 9, 10 on the electrodes 1, 2. Complete omission of the solder layers is also possible in principle. However, this would reduce the electrical conductivity and the mechanical stability of the connection between the two electrodes compared to a design with solder layers.

[0028] The exothermically reacting material of reactive layer 4, e.g., a reactive Ni / Al foil, can be triggered by current flow, sparks, lasers, or an initiator, e.g., via a reactive Al / Pd wire. In the Figure 1A trigger contact 12 is schematically indicated here. When the exothermic reaction is triggered, the solder layers 9, 10, 11 are melted, resulting in a permanent electrical and mechanical connection. This process can also be supported by the onset of an electric current.

[0029] In Figure 2 The situation in the triggered state is shown as an example, in which the solder layers 9, 10, 11 have fused into a single solder layer 13 to establish the permanent electrical connection between the two electrodes 1, 2.

[0030] Figure 3Figure 1 shows another example of an embodiment of the proposed bridging device, in which the surface area of ​​the outer electrode 1 again completely surrounds the surface area of ​​the inner electrode 2. In the present example, this can be either rotationally symmetrical or rectangular. The two electrodes 1, 2 are again insulated from each other by a suitable insulator 5. A solder layer 9, 10 is applied to the surface areas of each electrode 1, 2. The bridging element 3 is arranged above the electrodes and, in the present example, rests on one or more spacers 16, as shown in the figure. The spacer(s) 16 can be made of either an insulator or an electrically conductive material.The use of an electrically insulating spacer has the advantage of enabling galvanically isolated triggering from the switched current path. Preferably, the spacer 16 is designed as a circumferential frame, so that a closed reaction chamber is formed over the surface areas of the electrodes 1, 2. The bridging element 3 rests on this spacer 16 only with its reactive layer 4. Solder layers 11, 14 are formed above and below the reactive layer 4, respectively.

[0031] Above the upper solder layer 14, an electrically conductive layer 15, e.g., a metal plate, is additionally arranged. The upper solder layer 14 can also be omitted. The same applies to the solder layer 11 or the two solder layers 9, 10, as already explained in connection with the preceding embodiment.

[0032] In the present example, a pre-stressed spring element 8 is used as a mechanical energy storage device, which is located in the Figures 3 and 4 The direction of force exerted by this spring element 8 is indicated by the spring element 8. The spring element 8 provides the necessary contact pressure when the bridging device is triggered and is held in its pre-tensioned initial mechanical state by the retaining force of the reactive layer 4. Between the spring element 8 and the reactive layer 4 is the electrically conductive layer 15 and, optionally, the additional solder layer 14, to reduce the resistance of the bridging element in the triggered state. The edge of the reactive layer 4 rests on the insulating or conductive spacer frame 16, thus holding the bridging element 3 in its position.

[0033] The bridging device is triggered by the exothermic reaction of the reactive layer 4. This melts the solder coating 11, 14 of the reactive layer and destroys the mechanical retention of the spring element 8. Consequently, the bridging element is pressed onto the lower electrodes 1, 2 and the solder layers 9, 10 located thereon, and the solder layers fuse together. This results in a permanent electrical and mechanical connection between the electrodes 1, 2. This process can be supported by the onset of current flow as soon as an initial connection has been established. The triggering of the exothermic material of the reactive layer 4 can be carried out in the same manner as already explained in connection with the preceding embodiment. Figure 4The figure shows the situation in the triggered state, where the bridging element 3 is pressed against the electrodes 1, 2. The destruction of the reactive layer 4 is also schematically indicated in this figure. In the present example, an additional thermal insulation layer 17 is provided between the electrically conductive layer 15 and the spring element 8. This layer serves to prevent the dissipation of the heat generated by the exothermic reaction.

[0034] In principle, the pressure element, in this example a spring element, can be made of either an electrically conductive material, such as a metal like copper or aluminum, or an electrically insulating material, such as a plastic. This pressure element can be firmly connected to the bridging element or simply rest loosely against it. The pressure element represents the mechanical energy storage device and is clamped between the bridging element and a support structure, such as a housing for the bridging device. This is not visible in the figures.

[0035] The bridging device is, in principle, suitable for both low voltages (e.g., battery cells with a few volts) and higher voltages (e.g., battery modules, battery packs, and fuel cells with several hundred volts). In the present example, the Figures 3 and 4A relatively large insulation distance can be set between electrodes 1 and 2, and also between the electrodes and the bridging element 3. This allows this bridging device to be used for higher electrical voltages than the bridging device of the Figures 1 and 2 .

[0036] Preferably, the proposed bridging device, as explained in the preceding examples, is integrated into or onto a battery cell, i.e., in the battery cell housing or on the battery cell housing. Reference symbol list

[0037] 1 First electrode 2 Second electrode 3 Bridging element 4 Reactive layer 5 Insulator 6 Electrically conductive layer 7 Bimetallic element 8 Spring element 9 Solder layer 10 Solder layer 11 Solder layer 12 Trigger contact 13 Solder layer 14 Solder layer 15 Electrically conductive layer 16 Spacer or frame 17 Thermal insulator

Claims

1. An electrical bypass device having - at least one first (1) and one second (2) electrical conductor, which are electrically insulated from one another and are arranged such that at least a first surface region of the first conductor (1) orientated in one spatial direction is spaced apart from at least a second surface region of the second conductor (2) orientated in the same spatial direction by a gap, wherein the first surface region surrounds the second surface region, - a bypass element (3) having at least one electrically conductive layer (6, 11, 14, 15) is arranged above the two surface regions, wherein the bypass element is designed in such manner that it covers the second surface region, the gap between the surface regions, and at least a part of the first surface region, and wherein the bypass element is designed as a mechanical energy store (7) which can be converted by thermal activation from a first mechanical state into a stable, second mechanical state in which the electrically conductive layer (6, 11, 14, 15) of the bypass element (3) makes electrical contact with the surface regions and consequently short circuits the two electrical conductors (1, 2), - wherein a layer or film made of one or more materials that react exothermally upon in response to suitable energy input is arranged above the two surface regions as a reactive element (4), in which an exothermic reaction can be triggered, the thermal energy from which causes the mechanical energy store (7, 8) to be converted to the stable, second mechanical state.

2. An electrical bypass device having - at least one first (1) and one second (2) electrical conductor, which are electrically insulated from one another and are arranged such that at least a first surface region of the first conductor (1) orientated in one spatial direction is spaced apart from at least a second surface region of the second conductor (2) orientated in the same spatial direction by a gap, wherein the first surface region surrounds the second surface region, - a bypass element (3) having at least one electrically conductive layer (6, 11, 14, 15) is arranged above the two surface regions, wherein the bypass element is designed in such manner that it covers the second surface region, the gap between the surface regions, and at least a part of the first surface region, and wherein the bypass element is connected to a mechanical energy store (8) of the electrical bypass device which can be converted by thermal activation from a first mechanical state into a stable, second mechanical state in which the electrically conductive layer (6, 11, 14, 15) of the bypass element (3) makes electrical contact with the surface regions and consequently short circuits the two electrical conductors (1, 2), - wherein a layer or film made of one or more materials that react exothermally upon in response to suitable energy input is arranged above the two surface regions as a reactive element (4), in which an exothermic reaction can be triggered, the thermal energy from which causes the mechanical energy store (7, 8) to be converted to the stable, second mechanical state.

3. The bypass device according to Claim 1 or 2, characterized in that the first and the second surface regions are each covered with a layer (9, 10) of an electrically conductive material, which has a lower melting point than the electrical conductors (1, 2), and the reactive element (4) is dimensioned and arranged so that the two layers (9, 10) of the electrically conductive material are melted by the thermal energy released in the exothermic reaction of the reactive element (4) and thus form a soldered connection with the electrically conductive layer (6, 11, 14, 15) of the bypass element (3).

4. The bypass device according to any one of Claims 1 to 3, characterized in that a side of the bypass element (3) facing the surface regions is covered with a layer (11) of an electrically conductive material which has a lower melting point than the electrical conductors (1, 2), or the electrically conductive layer (6) of the bypass element (3) is made from a material of such kind, and the reactive element (4) is dimensioned and arranged such that said electrically conductive material is melted by the thermal energy released in the exothermic reaction of the reactive element (4), and a soldered connection is thus formed with the electrical conductors (1, 2) or with the electrically conductive material applied to the surface regions of the electrical conductors (1, 2).

5. The bypass device according to one of Claims 1, 3 or 4, characterized in that the mechanical energy store (7) of the bypass element (3) is a layered composite of at least two materials with different thermal expansion characteristics, which can assume two stable bending states as the first and second mechanical states.

6. The bypass device according to Claim 5, characterized in that the layered composite is formed by a bimetallic layer.

7. The bypass device according to Claim 5 or 6, characterized in that the bypass element (3) is constructed in the form of a dome above the enclosed region.

8. The bypass device according to Claim 7, characterized in that the second surface region is offset in height below the first surface region.

9. The bypass device according to any one of Claims 2 to 4, characterized in that before triggering the exothermic reaction, the mechanical energy store (8) is prevented from passing from the first to the second mechanical state by a retaining force of the reactive element (4).

10. The bypass device according to Claim 9, characterized in that the mechanical energy store (8) is an elastic element, in particular a spring element, which is held in a preloaded state as the first mechanical state by the reactive element (4).

11. The bypass device according to Claim 10, characterized in that a carrier structure is arranged above the bypass element (3) and the elastic element and is firmly connected to the first and / or second electrical conductor (1, 2), wherein the elastic element is clamped between the support structure and the bypass element (3).

12. The bypass device according to any one of Claims 9 to 11, characterized in that the reactive layer (4) is supported on one or more spacers (16) arranged around the enclosed region.

13. The bypass device according to any one of Claims 9 to 12, characterized in that the bypass element (3) has a thermally insulating layer (17) at the transition to the mechanical energy store (8).

14. A battery cell, in which a bypass device according to any one of Claims 1 to 13 has been integrated, or on which a bypass device according to any one of Claims 1 to 13 is arranged.