Short-circuit element of an electrochemical cell

Abstract

The invention relates to a short-circuiting element (10) of an electrochemical cell, which is assigned to a second, redundant monitoring circuit of the electrochemical cell in addition to a first monitoring circuit. The short-circuiting element (10) is in a low-resistance activated state (52) through which a heat-generating electric current flows. In the low-resistance activated state (52) of the short-circuiting element (10), a low-melting-point substrate (22) stored therein creates an electrically conductive connection (48) between a first and a second current-carrying electrode (26, 28). Furthermore, the invention relates to the use of the short-circuiting element (10) for preventing overvoltages in electrochemical cells, in particular battery cells for mobile or stationary applications.

Description

Technical field

[0001] The invention relates to a short-circuiting element (10) of an electrochemical cell, which is assigned to a second, redundant monitoring circuit of the electrochemical cell in addition to a first monitoring circuit. The short-circuiting element is activated in a low-resistance state by a heat-generating electric current. Furthermore, the invention relates to the use of the short-circuiting element to prevent overvoltages in electrochemical cells, in particular battery cells for mobile or stationary applications. State of the art

[0002] DE 10 2017 218 916 A1 relates to an electrical bridging element and an electrical energy storage device. The electrical bridging element comprises at least a first and a second electrical conductor, each with an insulating layer, as well as a reaction film, a solder layer, and a semiconductor switch. The electrical conductors are spaced apart and electrically insulated from one another and are bridged by the solder layer and the reaction film. The semiconductor switch, the reaction film, and the solder layer are arranged on the electrical conductors such that the semiconductor switch is configured to trigger an exothermic reaction of the reaction film, in which the solder layer at least partially melts. This creates an electrically conductive connection between the electrical conductors.

[0003] DE 10 2017 218 920 A1 relates to an electrical bridging element comprising at least a first and a second electrical conductor, a reaction film, a solder layer, and a printed circuit board that electrically insulates the electrical conductors from one another. The reaction film, the printed circuit board, and the solder layer are arranged between the electrical conductors in such a way that, during an exothermic reaction, the reaction film melts the solder layer, so that the solder of the solder layer creates an electrically conductive connection between the electrical conductors.

[0004] EP 0 170 088 A1 describes a bridging element connected in parallel to a memory cell. The bridging element is formed by a semiconductor device connected to one terminal via other electrical components, some of which are spring-like, while it is directly connected to the other terminal. If such a memory cell experiences high resistance, the entire current flows through the bridging element. This results in a temperature increase within the semiconductor device and the formation of a low-resistance connection between the two terminals.

[0005] EP 0 297 421 A2 relates to a bridging element for safeguarding battery cells. The bridging element is connected in parallel to a single battery cell or a group of battery cells in a high-temperature storage battery consisting of a large number of series-connected electrochemical battery cells. It serves both to balance the charge state of intact battery cells and to irreversibly bridge damaged cells that have failed with high resistance. It comprises two semiconductor devices arranged in series, in particular semiconductor diodes, varistors, or NTC resistors, each with different current / voltage characteristics. In the event of potentiostatic overcharging of a battery cell, the first semiconductor device becomes low-resistance, so that the current flow necessary for charging further battery cells is determined solely by the leakage current of the second semiconductor device.In the event of a high-resistance failure of a destroyed battery cell, both semiconductor components alloy through and irreversibly close the cell to a low-resistance state.

[0006] Electrochemical cells, such as fuel cells, lithium battery cells, electrolyzers, and cells for the electrochemical conversion of CO2, must be operated within a specific operating window. Operating the electrodes and the electrochemical cell outside this window can lead to dangerous electrochemical reactions and the destruction of the electrolyte and the electrodes. Control and monitoring circuits are provided for conventional electrochemical cells to monitor this safe operating window; however, these require a reference electrode and can also be prone to failure. Disclosure of the invention

[0007] According to the invention, a short-circuiting element of an electrochemical cell is proposed, which is arranged in a second, redundant monitoring circuit that is additionally assigned to a first monitoring circuit of the electrical cell, wherein the short-circuiting element is traversed by a heat-generating electric current in a low-resistance activated state. In the low-resistance activated state of the short-circuiting element, a low-melting-point substrate stored therein creates an electrically conductive connection between a first and a second current-carrying electrode.

[0008] The short-circuit element proposed according to the invention initiates a melting process by the input of heat, by means of which an electrical short circuit between two current-carrying electrodes can be generated without a switch.

[0009] Advantageously, the low-melting substrate is a metal or a metallic alloy, in particular tin, indium, lead, bismuth and alloys thereof, especially tin-indium and tin-indium-bismuth alloys, alloys such as Wood's metal and Rose's metal, and generally low-melting alloys such as those used for soldering processes.

[0010] In an advantageous further development of the short-circuiting element proposed according to the invention, this element has a gas-tight housing which defines an interior space.

[0011] The short-circuit element proposed according to the invention provides that a separate chamber is arranged in the interior, which accommodates an expandable volume of gas or fluid.

[0012] In the short-circuit element proposed according to the invention, the medium contained in this separate chamber is advantageously an expandable gas or fluid volume, an inert gas, in particular N2 or Ar or also H2O, hydrocarbons such as propane, propene, butane, butene, pentane, hexane and others, or fluorinated hydrocarbons or fluorocarbon compounds, such as those also used as coolants.

[0013] In the short-circuit element proposed according to the invention, it is further provided that when the short-circuit element is heated, the expandable gas / fluid volume in the separate chamber displaces the low-melting substrate in the interior in such a way that an electrically conductive connection is created between the first and second current-carrying electrode.

[0014] In an advantageous further development of the short-circuit element proposed according to the invention, it is further provided that the expandable gas / fluid volume in the separate chamber displaces the low-melting substrate in the interior, surrounding the first and second current-carrying electrode.

[0015] Advantageously, switches or other malfunction-prone mechanisms can be dispensed with.

[0016] Furthermore, the short-circuit element proposed according to the invention is characterized in that, in one embodiment, the expandable gas / fluid volume acts upon a separating plate or elastic membrane which is movable within the gas-tight housing and sealed to the housing edge, and which pushes the low-melting substrate in the interior towards the first and second current-carrying electrodes when pressure builds up in the chamber of the expandable medium.

[0017] In one embodiment of the short-circuit element proposed according to the invention, it is designed as a transistor, wherein the first current-carrying electrode is designed as the emitter and the second current-carrying electrode is designed as the collector.

[0018] In a further embodiment of the short-circuit element proposed according to the invention, it is designed as a MOSFET, wherein the first current-carrying electrode is designed as the source and the second current-carrying electrode as the drain.

[0019] Furthermore, the invention relates to the use of the short-circuiting element to prevent overvoltages in electrochemical cells, in particular battery cells for mobile or stationary applications. Advantages of the invention

[0020] The short-circuiting element proposed according to the invention protects an electrochemical cell in such a way that the occurrence of overvoltages across it is reliably prevented. The short-circuiting element proposed according to the invention can be implemented as a MOSFET, a semiconductor triode (TRIAC), an insulated-gate bipolar transistor (IGBT), or a transistor. Advantageously, the short-circuiting element proposed according to the invention is incorporated into a parallel monitoring circuit, thus ensuring that immediate tripping occurs in the event of an overvoltage. The short-circuiting element proposed according to the invention utilizes the fact that it generates heat upon activation, with activation occurring via an electrical signal at the gate or base electrode in a low-resistance state. This is a reversible switching process that is often used in power supply circuits.The heat is generated by the electric current flowing through the short-circuit element in the activated low-resistance state, according to the following relationship: P=I×RI with P = power at the short-circuit element I = Current through the short-circuit element and R I = Internal resistance of the short-circuit element

[0021] In particular, the electrical resistance of the controllable short-circuiting element can be adjusted to achieve maximum heating of the element without destroying it. In the short-circuiting element proposed according to the invention, a low-melting-point substrate, in the form of a metal or metal alloy such as tin, is melted in the activated state. This substrate is moved within the interior of the short-circuiting element in such a way that the molten metal creates an electrically conductive connection between a first and a second current-carrying electrode. In the case of a short-circuiting element designed as a transistor, the first and second electrodes are the emitter and collector, respectively. In the case of a short-circuiting element designed as a MOSFET, the first and second electrodes are the source and drain.

[0022] Advantageously, the short-circuit element proposed according to the invention is provided with a separate chamber in its interior, which is filled with an expandable gas or fluid in the form of an inert gas such as argon or N2, or even with water, which evaporates upon heat generation. This causes the expandable chamber in the interior of the short-circuit element proposed according to the invention to expand.Since the low-melting substrate, in the form of a metal or metallic alloy, melts simultaneously due to the increasing heat generation within the short-circuit element, this now easily displaceable or deformable substrate is displaced within the interior of a gas-tight housing of the short-circuit element by the expanding chamber in such a way that an electrically conductive connection, namely a short-circuit connection, is formed between the first and second current-carrying electrodes.

[0023] The separate chamber, located within the gas-tight housing of the short-circuiting element, ensures that the molten, low-melting-point substrate is displaced in the direction where the first and second current-carrying electrodes, as well as a third electrode, are located. This guarantees that, as heat is generated, an electrically conductive connection—namely, a short circuit—forms very quickly between the first and second current-carrying electrodes, without the need for a separate actuator or actuator.

[0024] In a further advantageous embodiment of the short-circuit element proposed according to the invention, a movable partition plate or the like can also be arranged in the interior of the gas-tight housing of the short-circuit element. This partition plate is positioned between the chamber filled with the expandable gas or fluid volume on the one hand and the supply of low-melting substrate in the interior of the gas-tight housing on the other. As the expandable gas or fluid volume expands, the partition plate moves within the chamber, displacing the low-melting substrate, which also melts due to increasing heat generation, uniformly towards the current-carrying electrodes. A short-circuit element of this type can also be operated in a simpler manner without generating an expanding volume.However, this requires that a vacuum be present in the short-circuit element and that gravity pulls the mass to be melted, which forms the short circuit, downwards over the current-carrying contacts in such a way that an electrically conductive connection is created. Brief description of the drawings

[0025] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0026] They show: Fig. 1 a schematic representation of an embodiment of the short-circuit element proposed according to the invention, Fig. 2 an embodiment of the short-circuiting element proposed according to the invention with a partition plate integrated into the interior between the separate chamber and the supply of low-melting substrate and Fig. 3 the short-circuit element proposed according to the invention in the activated state forming an electrically conductive connection between the first and second current-carrying electrodes. Embodiments of the invention

[0027] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0028] Fig. Figure 1 shows a first embodiment of the short-circuiting element 10 proposed according to the invention. As shown in Figure 1 Fig. In Figure 1, the short-circuiting element 10 is provided with a housing 12, the housing wall 14 of which is essentially gas-tight. The housing 12 of the short-circuiting element 10 encloses an interior space 16. The short-circuiting element 10 can be configured as a transistor 32, a MOSFET 34, a semiconductor triode (TRIAC), or an IGBT semiconductor device. The in Fig. A short-circuiting element 10, shown schematically, is preferably arranged in a monitoring circuit, which is additionally formed to a monitoring circuit of an electrochemical cell. The short-circuiting element 10 according to the illustration in Fig. In a monitoring circuit of the electrochemical cell, for example a secondary monitoring circuit, component 1 serves as a redundant component in the event that components of the primary monitoring circuit of the electrochemical cell should fail, so that the electrochemical cell is protected against any overvoltage that may occur. The electrochemical cell, which is protected against voltages by the short-circuit element 10 proposed according to the invention, is, for example, a fuel cell, a lithium battery, an electrolyzer, or electrochemical cells for capturing CO2.

[0029] As can be seen from the schematic representation according to Fig. As can be seen from Figure 1, a separate chamber 18 is incorporated within the interior 16 of the short-circuiting element 10 presented here. The separate chamber 18 has a flexible wall and accommodates an expandable gas / fluid volume 20. This can be either an inert gas, such as N2 or argon, or alternatively, the separate chamber 18 within the interior 16 can be filled with water, which, when the interior 16 of the short-circuiting element 10 is heated, transitions into a gaseous state, i.e., becomes vaporous, so that the volume in the separate chamber 18 within the interior 16 of the short-circuiting element 10 increases.

[0030] Adjacent to the separate chamber 18 in the interior 16 of the short-circuiting element 10 is a supply of a low-melting substrate 22. This can be, for example, a metal or a metallic alloy 24. The low-melting substrate 22 can be, for example, tin, indium, lead, bismuth, and alloys thereof, in particular tin-indium and tin-indium-bismuth alloys, as well as alloys such as Wood's metal or Rose's metal, or generally low-melting alloys such as those used for soldering processes. Temperature ranges between 60°C to 120°C and 120°C to 220°C are of particular interest here.

[0031] Into the interior 16 of the gas-tight housing 12 of the short-circuiting element 10 proposed according to the invention, a first current-carrying electrode 26, a second current-carrying electrode 28 and a further electrode 30 protrude.

[0032] The electrodes 26, 28, 30 in question are each led out of the housing 12 of the short-circuiting element 10 through gas-tight feedthroughs 36.

[0033] In the case where the short-circuiting element 10 is configured as a transistor 32, the first current-carrying electrode 26 forms an emitter 26.1, and the second current-carrying electrode 28 forms a collector 28.1. In the case where the short-circuiting element 10 is a MOSFET 34, the first current-carrying electrode 26 forms a source 26.2, while the second current-carrying electrode 28 forms a drain 28.2.

[0034] The interior 16 of the housing 12 of the short-circuiting element 10 can be filled with a gas, such as air; however, a vacuum can also prevail.

[0035] From the representation according to Fig. Figure 2 shows a variant embodiment of the short-circuiting element 10 proposed according to the invention. In the Fig. In the embodiment of the short-circuiting element 10 proposed according to the invention, shown in Figure 2, a movable partition plate 38 is located between the separate chamber 18 and the supply of the low-melting substrate 22. This partition plate is movable in a direction of movement 40 during the expansion of the separate chamber 18 and can be provided with a circumferential seal 42 along its circumference. When the expandable gas / fluid volume 20, which is stored in the separate chamber 18, expands, the supply of low-melting substrate 22 opposite the movable partition plate 38 is uniformly supplied with gas in the direction of the electrodes 26, 28, 30 projecting into the housing 12. These electrodes are arranged analogously to the illustration shown in Figure 2. Fig. 1 led out laterally from the gas-tight housing 12 of the short-circuiting element 10 by means of a gas-tight feedthrough 36.

[0036] Fig. Figure 3 shows the short-circuit element 10 proposed according to the invention in the activated state 52.

[0037] From the representation according to Fig. Figure 3 shows that when the interior 16 of the short-circuiting element 10 is heated by a current passing through it, the separate chamber 18, or rather the expandable gas / fluid volume 20 stored therein, increases in volume, i.e., expands and comes into contact with the low-melting-point substrate 22, which is also contained in the interior 16 of the housing 12. Due to the heating of the interior 16 of the short-circuiting element 10, the low-melting-point substrate 22 begins to melt. Temperatures between 60°C and 120°C and between 120°C and 220°C are of particular interest.

[0038] As the low-melting substrate 22 melts in the interior 16, the expansion of the expandable gas / fluid volume 20 in the separate chamber 18 displaces the low-melting substrate 22 towards the electrodes 26, 28, 30. This results in the filling of a space between, for example, the first current-carrying electrode 26 and the second current-carrying electrode 28, a space which, for example, has a width equal to an electrode spacing 44. An extended volume 46 of the low-melting substrate 22 penetrates the spaces between the essentially parallel electrodes 26, 28, 30, fills them, and, in particular, forms an electrically conductive connection 28, i.e., a short circuit, between the first current-carrying electrode 26 and the second current-carrying electrode 28.Thus, in the activated state 52, at the corresponding temperature in the interior 16 of the short-circuiting element 10, the first and second electrodes are short-circuited 50.

[0039] The separate chamber 18, which is formed in the interior 16 of the housing 12, forces the low-melting substrate 22 towards the first and second electrodes 26, 28, which are to be short-circuited together, so that between these, as shown in the illustration Fig. 1 in the remaining free space between the first current-carrying electrode 26 and the second current-carrying electrode 28, the low-melting substrate 22 enters and forms said electrically conductive connection 48.

[0040] The displacement of the low-melting substrate 22, which melts as heat develops in the interior 16, thus occurs either according to the illustration in Fig. 2 by said movable separating plate 38 or directly by the side wall of the separate chamber 18 adjacent to the low-melting substrate 22, in which the expanding gas or fluid volume 20 is contained.

[0041] The activation of the short-circuit element 10 proposed according to the invention is effected essentially by the voltage or by a start-up signal from a processing unit. As soon as the short-circuit element 10 is in its activated state 52 as shown in the illustration in Fig. Once the protective short circuit has been transferred to the 3-phase circuit, it remains stable in the low-resistance state and is independent of the availability of a control voltage or the higher-level control system. Thus, the short-circuiting element 10 is independent with regard to safety requirements. The short-circuiting element 10 proposed according to the invention, when incorporated into a corresponding monitoring circuit, provides stable monitoring of the electrochemical cell. The low-melting-point substrate 22, in the form of a metal or a metallic alloy 24, for example indium, lead, bismuth, and alloys thereof, in particular tin-indium and tin-indium-bismuth alloys, as well as alloys such as Wood's metal or Rose's metal, generally low-melting-point alloys such as those used for soldering processes, constitutes a stable short-circuiting element 10.The short-circuiting element 10 is indestructible, even in view of the melting of the low-melting substrate 22 taking place within it. The formation of the electrically conductive connection 48 between the first current-carrying electrode 26 and the second current-carrying electrode 28, i.e., the bridging of the free electrode gap 44, is ensured because the expandable separate chamber 18, or the expandable gas / fluid volume 20 contained therein, expands until the remaining interior space 16 of the housing 12 in the area of ​​the gas-tight electrode feedthroughs 36 is completely filled by the melted low-melting substrate 22, and it is ensured that said electrically conductive connection 48 forms between the first current-carrying electrode 26 and the second current-carrying electrode 28.

[0042] Furthermore, the invention relates to the use of the short-circuiting element 10 according to the illustrations of the Fig. 1, Fig. 2 to Fig. 3 for monitoring overvoltages on electrochemical cells, fuel cells, lithium batteries and electrolyzers for binding CO2.

[0043] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible that fall within the bounds of what is considered skilled in the art. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited Patent Literature

[0000] DE 10 2017 218 916 A1

[0002] DE 10 2017 218 920 A1

[0003] EP 0 170 088 A1

[0004] EP 0 297 421 A2

[0005]

Claims

[1] Short-circuit element (10) of an electrochemical cell, which is assigned to a second, redundant monitoring circuit in addition to a first monitoring circuit of the electrochemical cell, wherein the short-circuit element (10) is in a low-resistance activated state (52) through which a heat-generating electric current flows, characterized by , that in the low-resistance activated state (52) of the short-circuit element (10) a low-melting substrate (22) stored therein generates an electrically conductive connection (48) between a first and a second current-carrying electrode (26, 28). [2] Short-circuit element (10) according to claim 1, characterized by, that the low-melting substrate (22) is a metal or a metallic alloy (24), in particular tin, indium, lead, bismuth and alloys thereof, in particular tin-indium and tin-indium-bismuth alloys, as well as alloys such as Wood's metal or Rose's metal or generally low-melting alloys such as those used for soldering processes. [3] Short-circuit element (10) according to one of claims 1 and 2, characterized by that this has a gas-tight housing (12) which defines an interior space (16). [4] Short-circuit element (10) according to claims 1 to 3, characterized by , that in the interior (16) a separate chamber (18) is arranged which accommodates an expandable gas or fluid volume (20). [5] Short-circuit element (10) according to claim 4, characterized by, that the separate chamber (18) contains an inert gas, in particular N2 or Ar or H2O, or hydrocarbons such as propane, propene, butane, butene, pentane, hexane and others, or fluorinated hydrocarbons or fluorocarbon compounds, such as those also used as coolants. [6] Short-circuit element (10) according to claims 1 to 5, characterized by , that when the short-circuit element (10) is heated, the expandable gas / fluid volume (20) in the separate chamber (18) displaces the low-melting substrate (22) in the interior (16) in such a way that an electrically conductive connection (48) is formed between the first and second current-carrying electrodes (26, 28). [7] Short-circuit element (10) according to claim 6, characterized by, that the expandable gas / fluid volume (20) in the separate chamber (18) displaces the heat-low melting substrate (22) in the interior (16), surrounding the first and second current-carrying electrodes (26, 28). [8] Short-circuit element (10) according to claims 1 to 5, characterized by , that the expandable gas / fluid volume (20) acts upon a movable separating plate (38), which forces the low-melting substrate (22) in the interior (16) towards the first and second current-carrying electrodes (26, 28). [9] Short-circuit element (10) according to claims 1 to 8, characterized by , that in an embodiment of the short-circuit element (10) as transistor (32) the first current-carrying electrode (26) is designed as emitter (26.1) and the second current-carrying electrode (28) as collector (28.1). [10] Short-circuit element (10) according to claims 1 to 8, characterized by, that in an embodiment of the short-circuit element (10) as MOSFET (34) the first current-carrying electrode (26) is designed as Source (26.2) and the second current-carrying electrode (28) as Drain (28.2). [11] Use of the short-circuiting element (10) according to any one of claims 1 to 10 for avoiding overvoltages on electrochemical cells, in particular battery cells for mobile or stationary applications.

Images