Test device for rapid electrochemical characterization of an electrochemical cell, method for operating the test device and use of the test device

Abstract

The invention relates to a test device (10) for an electrochemical cell (12), in particular for a high-temperature electrochemical cell, with at least one measuring unit (14) for very rapid detection of at least one test parameter of the electrochemical cell (12) and with at least one sample holder (16) for specifying a defined position of the electrochemical cell (12) relative to the measuring unit (14) during the detection of the test parameter. It is proposed that at least one basic body (18, 20) of the sample holder (16) is made at least partially, in particular at least substantially entirely, of metal or ceramic.

Description

State of the art

[0001] A test device for an electrochemical cell, in particular for an electrochemical high-temperature cell, has already been proposed, comprising at least one measuring unit for detecting at least one test parameter of the electrochemical cell and at least one sample holder for specifying a defined position of the electrochemical cell relative to the measuring unit during the detection of the test parameter. Disclosure of the invention

[0002] The invention is based on a test device for an electrochemical cell, in particular for an electrochemical high-temperature cell, with at least one measuring unit for detecting at least one test parameter of the electrochemical cell and with at least one sample holder for specifying a defined position of the electrochemical cell relative to the measuring unit during the detection of the test parameter.

[0003] It is proposed that at least one base body of the sample holder be made at least partially, in particular at least substantially entirely, of metal and / or ceramic. The test device is preferably intended for quality testing of the electrochemical cell. The test device is preferably intended for testing an electrochemical cell designed as a fuel cell, preferably as a high-temperature fuel cell, and / or as an electrolysis cell, in particular as a high-temperature electrolysis cell. The electrochemical high-temperature cell preferably has an intended operating temperature of more than 100°C, preferably more than 400°C, particularly preferably more than 600°C.For example, the test device is intended for quality testing of solid oxide fuel cells and / or solid oxide electrolysis cells and / or molten carbonate fuel cells and / or molten carbonate electrolysis cells and / or proton-conducting electrochemical cells.

[0004] The electrochemical cell to be tested preferably comprises at least one cathode, at least one anode, and at least one electrolyte arranged between the at least one cathode and the at least one anode. The electrochemical cell may additionally comprise an anode-side or cathode-side substrate, in particular a metallic support or a ceramic support, and / or further functional layers, such as a diffusion barrier, an electron barrier layer, or the like. The sample holder preferably comprises at least one anode-side base body, which is provided for an anode-side arrangement on the electrochemical cell. The sample holder preferably comprises at least one cathode-side base body, which is provided for a cathode-side arrangement on the electrochemical cell.During the recording of the test parameter, the anode-side base body and the cathode-side base body are preferably provided to hold, in particular clamp, the electrochemical cell from two opposite sides. The cathode-side base body and the anode-side base body preferably form a base body pair of the sample holder. Preferably, mutually facing holding surfaces of the base bodies of the base body pair, between which the electrochemical cell is arranged for carrying out the quality test, are designed to hold precisely one electrochemical cell. Preferably, the base bodies each comprise precisely one holding surface. The holding surface of one, in particular each, of the base bodies is preferably formed as a continuous unit. Alternatively, the holding surface of one, in particular each, of the base bodies is divided into several spaced-apart partial surfaces. The sample holder preferably comprises precisely one base body pair.Alternatively, the sample holder comprises more than two base bodies, in particular several base body pairs and / or a different number of cathode-side base bodies and anode-side base bodies, and / or several sample holders, for example for simultaneous quality testing of several electrochemical cells. The base bodies are preferably designed to be movable relative to one another, wherein in particular one of the base bodies or both of the base bodies of the base body pair can be arranged to be movable relative to a housing of the test device. Particularly preferably, at least one, in particular both, of the base bodies are mounted to be movable along a direction that is at least substantially perpendicular to its, in particular respective, holding surface.The sample holder preferably comprises at least one actuator for moving the base bodies of a base body pair towards one another, thereby holding the electrochemical cell, or for moving them away from one another, thereby releasing the test device from the electrochemical cell. The at least one actuator is preferably provided for setting a maximum pressure exerted by the sample holder on the electrochemical cell. The actuator can be pneumatic or hydraulic and / or comprise an electric motor for moving the base body. The actuator can be provided for moving precisely one of the base bodies relative to the housing of the test device, or can be provided for moving several, in particular both, base bodies of the sample holder relative to the housing of the test device, for example via a gear, a clamp joint, or the like of the sample holder.Alternatively, the test device comprises an actuator for moving the base body and another actuator for moving another base body of the test device.

[0005] The at least one base body preferably consists of more than 25%, preferably more than 50%, particularly preferably more than 75%, and most preferably more than 90%, based on weight and / or volume, of at least one metal, in particular a single metal, multiple metals, or an alloy. For example, the base body consists entirely of metal, in particular apart from a natural or artificially induced surface layer of an oxide of the metal. For example, the base bodies consist of a high-temperature-resistant steel, for example Inconel 600, or titanium. Alternatively, the base bodies consist of Al2O3 or ZrO2.In the case of an incomplete design of the base body made of metal, non-metallic components of the base body include, for example, insulating elements embedded in the metallic part of the base body and / or integrally connected thereto, in particular electrical and / or thermal, or fibers or particles inserted into the metal to adapt an electrical or mechanical property of the base body, or a coating, in particular a corrosion protection, or the like.

[0006] The quality check preferably comprises the recording of at least one test parameter, in particular a plurality of test parameters. The quality check comprises, for example, a determination of a fluid tightness of the electrochemical cell as a test parameter. The quality check comprises, for example, a recording of a characteristic of an electrochemical conversion of at least one test fluid through the electrochemical cell as, in particular, a further test parameter. The characteristic is preferably an open circuit voltage and / or an electrical power density of the electrochemical cells, in particular as a function of a predetermined electrical current density through the electrochemical cell, in particular the electrolyte. The test device preferably comprises at least one fluid supply unit for supplying the electrochemical cell, in particular the cathode and / or the anode, with at least one, in particular with at least one each, test fluid.The test device preferably comprises an electrical unit for integrating the electrochemical cell into an electrical circuit. The measuring unit preferably comprises at least one sensor element integrated into the circuit to detect the at least one test parameter. The sensor element is preferably provided for detecting an electrical variable of the electrical circuit, for example an electrical voltage, an electrical current, an electrical power, an impedance, a conductance, or the like. The measuring unit can determine the electrical variable directly as a test parameter or the at least one test parameter as a function of the electrical variable. Additionally or alternatively, the measuring unit comprises at least one fluid sensor element integrated into the fluid supply unit for detecting at least one fluid variable of the at least one test fluid.The fluid variable may be, for example, a pressure drop across the electrochemical cell, a flow rate, a temperature, a composition downstream and / or upstream of the electrochemical cell, or the like.

[0007] The measuring unit preferably determines the at least one test parameter as a function of the at least one fluid variable. Particularly preferably, the test device comprises a control or regulating unit for setting, in particular regulating, the at least one fluid variable to a constant value, while the measuring unit records the test parameter, in particular as a function of the electrical variable. Alternatively or additionally, the fluid variable is recorded as a test parameter. A “control or regulating unit” is to be understood in particular as a unit with at least one control electronics unit. A “control electronics unit” is to be understood in particular as a unit with a processor unit and with a memory unit as well as with an operating program stored in the memory unit.The measuring unit may comprise an output element for outputting the at least one test parameter and / or a storage element for storing the at least one test parameter.

[0008] “Intended” should be understood in particular to mean specially programmed, designed and / or equipped. The fact that an object is intended for a specific function should be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state. The expression “essentially perpendicular” is intended here in particular to define an orientation of a direction relative to a reference direction, wherein the direction and the reference direction, in particular viewed in a projection plane, enclose an angle of 90° and the angle has a maximum deviation of in particular less than 8°, advantageously less than 5° and particularly advantageously less than 2°.

[0009] The design according to the invention makes it possible to provide a test device by means of which an advantageously very fast and automated quality test of electrochemical cells, in particular of electrochemical cells produced in series, can be achieved.

[0010] It is further proposed that the test device comprise at least one heating unit in the at least one base body of the sample holder for setting a test temperature of the electrochemical cell. The test temperature preferably corresponds to an intended operating temperature of the electrochemical cells. For example, the test temperature is at least 200°C, preferably at least 350°C, particularly preferably at least 500°C. The heating unit preferably comprises at least one, in particular at least one per base body, electrical heating element for setting the test temperature. Preferably, the heating unit comprises at least one anode-side heating element, which is preferably arranged within, or alternatively on, the anode-side base body. Preferably, the heating unit comprises at least one cathode-side heating element, which is preferably arranged within, or alternatively on, the cathode-side base body.Alternatively, the base bodies themselves form electrical heating elements of the heating unit. The heating elements / heating unit preferably have a heating output of at least 300 W, preferably at least 500 W, in particular at least 750 W. The measuring unit preferably comprises at least one temperature sensor element, for example a thermocouple, for detecting the test temperature. The temperature sensor element is preferably arranged within or on the anode-side base body. The temperature sensor element is preferably embedded in the holding surface of the anode-side base body. Alternatively, the temperature sensor element or another temperature sensor element is arranged in the fluid supply unit downstream of the electrochemical cell or is designed for non-contact-based detection of the test temperature, for example in the form of a pyrometer, a thermal imaging camera, or the like.The test device preferably comprises at least one additional temperature sensor element for detecting the temperature of the base body, which is arranged set back from the holding surface in the base body. Due to the inventive design of the test device, the electrochemical cell can advantageously be brought to the test temperature quickly, in particular in less than 30 seconds. In particular, the overall duration of the quality test can advantageously be kept short.

[0011] It is further proposed that the at least one base body of the sample holder is partially hollow for supplying fluid to the electrochemical cell. Preferably, at least one line element of the fluid supply unit is at least partially arranged in the base bodies or is formed at least partially by the base bodies. In particular, at least one of the base bodies can be designed as a solid block, wherein this base body comprises bores, shafts, channels or the like for guiding the at least one test fluid or for receiving the at least one line element. Preferably, a bulk density of the solid block is less than 50% lower than a true density of the solid block, preferably by less than 33%, particularly preferably by less than 25%.Alternatively, at least one of the base bodies can be designed as a hollow body, in particular as a tube, whose bulk density exceeds its true density, in particular by more than 25%, preferably by more than 33%, particularly preferably by more than 50%. For example, an outer diameter of the base body is at most 1.5 times as large, preferably at most 1.3 times as large, preferably at most 1.2 times as large as an inner diameter of the base body.

[0012] The fluid supply unit preferably comprises at least one anode-side conduit element arranged in the anode-side base body or formed by it. An outlet of the anode-side fluid guide element is preferably arranged in the holding surface of the anode-side base body. An inlet of the anode-side fluid guide element is preferably arranged on a side of the anode-side base body facing away from the holding surface. The anode-side fluid guide element is preferably provided for supplying the anode with the at least one test fluid. The fluid supply unit preferably comprises at least one anode-side discharge element for discharging a product fluid emerging from the anode and resulting from the test fluid. The discharge element is preferably arranged in the anode-side base body or formed by it.An inlet of the anode-side discharge element is preferably arranged in the holding surface of the anode-side base body. An outlet of the anode-side discharge element is preferably arranged on a side of the anode-side holding body facing away from the holding surface of the anode-side base body. Preferably, the at least one heating element arranged in the anode-side base body is arranged in or on the anode-side line element. Preferably, the fluid supply unit comprises at least one cathode-side line element and / or one cathode-side discharge element in the cathode-side base body. The cathode-side fluid guide element and / or the cathode-side discharge element are preferably designed analogously to the anode-side fluid guide element or the anode-side discharge element.The anode-side elements arranged in the base bodies and the cathode-side elements of the fluid supply unit can be of identical construction or be specifically designed for the test fluids to be used, for example, with regard to a desired flow rate, corrosion protection, leak-tightness, or the like. The inventive design advantageously allows the electrochemical cells and the at least one test fluid to be brought to the test temperature simultaneously, quickly, and efficiently.

[0013] It is further proposed that the sample holder comprises at least one contact element for physical contact with the electrochemical cell, which has a maximum surface area of ​​0.5 cm 2The at least one contact element preferably has its surface area in a plane that is at least substantially parallel to that of the holding surface. By “substantially parallel” is meant here in particular an alignment of a direction relative to a reference direction, in particular in a plane, wherein the direction has a deviation from the reference direction of in particular less than 8°, advantageously less than 5° and particularly advantageously less than 2°. Preferably, the contact element is arranged on the holding surface of at least one of the base bodies or is formed by this holding surface. The sample holder preferably comprises a contact element for each holding surface, in particular for each separate partial surface of the holding surface. The contact element is preferably made of an electrically conductive material, in particular metal.The contact element can be made of the same material as the base body or of a material different from the base body. The holding surface can be the same size as or larger than the contact element. The contact element can cover the holding surface at least partially, in particular only partially or at least substantially completely, from the viewing direction of an opposite further base body of the test device, or can be recessed into the holding surface, in particular at least substantially flush. “Substantially completely covering” is to be understood, in particular in a parallel projection along a direction perpendicular to the holding surface, as having an overlap whose surface area comprises at least 50%, preferably at least 75%, preferably at least 90%, of a surface area of ​​the holding surface."Substantially flush" should preferably be understood to mean flush except for an offset of less than 1 mm, preferably less than 500 µm, particularly preferably less than 250 µm, especially at the specified test temperature. The inventive design advantageously allows the test parameter to be determined with spatial resolution. In particular, different subregions of the electrochemical cell can be tested advantageously and easily. Furthermore, in the case of a homogeneously sintered electrochemical cell, conclusions can be drawn about the tightness and / or electrical performance of the entire electrochemical cell, advantageously without additional measurements.

[0014] It is further proposed that the sample holder comprises at least one electrical contact element arranged on the at least one base body for electrical contact with the electrochemical cell, which electrical contact element is designed in a mesh-like manner. Preferably, the electrical contact element is identical to the already mentioned contact element for physical contact with the electrochemical cell. Preferably, the electrical contact element is integrated into a direct current circuit of the electrical unit. Preferably, the electrical contact element is integrated into an alternating current circuit of the electrical unit. Alternatively, the sample holder comprises a specific direct current contact element and / or a specific alternating current contact element on the base body. Preferably, the electrical contact element is arranged at the outlet of the conduction element. In particular, the electrical contact element is permeable to the at least one test fluid.Particularly preferably, the electrical contact element is designed as a wire mesh. Alternatively, the electrical contact element is porous, as a perforated sheet, as a grid, or the like. The inventive design advantageously allows the distribution of the test fluid in the electrochemical cell and the flow of electrical current through the electrochemical cell to be kept concentric. In particular, the risk of distortion of the test parameter due to an electrical current flow that is not perpendicular to a contact surface between the electrical contact element and the electrochemical cell can be advantageously minimized.

[0015] It is further proposed that the sample holder comprises at least one electrical contact element, which is arranged on the at least one base body, in particular as already mentioned, for electrical contact with the electrochemical cell and which is made of platinum, nickel or gold. The electrical contact element on the anode-side base body is particularly preferably made of gold. The electrical contact element on the cathode-side base body is particularly preferably made of nickel. The electrical contact element is particularly preferably made of platinum wires, gold wires or nickel wires, which are arranged in a net-like manner, in particular woven. An electrical line of the electrical unit is preferably made of platinum or gold for integrating the electrical contact element into the circuit.Preferably, the electrical line of the electrical unit for integrating the electrical contact element into the circuit runs through the base body on which the electrical contact element is arranged. The inventive design allows an influence on the test parameter caused by the electrical contact element to be determined and taken into account in an advantageously reproducible and reliable manner.

[0016] Furthermore, a method for operating a test device according to the invention is proposed. In at least one method step, an electrochemical cell is preferably positioned in the test device, in particular automatically or manually. The sample holder preferably grips the electrochemical cell through a relative movement of the base bodies. The sample holder preferably establishes electrical contact between the electrical contact element of the anode-side base body and the electrochemical cell, as well as between the electrical contact of the cathode-side base body and the electrochemical cell, through the relative movement of the base bodies.

[0017] The heating unit preferably heats the anode-side base body and the cathode-side base body, and via these, the electrochemical cell transmits the test temperature. The at least one temperature sensor element preferably detects the temperature of the base body in which it is arranged. The control or regulating unit preferably controls the heating unit to set the test temperature, in particular to regulate it as a function of the at least one temperature sensor element. The control or regulating unit preferably specifies a temperature profile to be produced by the heating unit, comprising a heating phase, a measuring phase, and a cooling phase of the method. The at least one test parameter is preferably detected in the measuring phase.

[0018] The fluid supply unit preferably supplies at least one test fluid to the electrochemical cell for detecting the test parameter. It is conceivable that the fluid supply unit also supplies at least one fluid, for example the test fluid or a flushing fluid, in particular a protective gas, inert gas, and / or air, during heating or cooling of the electrochemical cell, for example for mass-based heat transfer into or out of the electrochemical cell.

[0019] The measuring unit preferably carries out at least one direct current measurement using the electrical unit to determine the test parameter. During the direct current measurement, the fluid supply unit of the electrochemical cell preferably supplies a hydrogen-containing test fluid, in particular a protective gas or pure hydrogen, through the anode-side base body. During the direct current measurement, the fluid supply unit of the electrochemical cell preferably supplies an oxygen-containing test fluid, in particular atmospheric air, synthetic air, or pure oxygen, through the cathode-side base body. A "pure" substance is preferably understood to mean a substance with a purity of at least 95%, preferably of at least 99%, particularly preferably of at least 99.9%.In the direct current measurement, the measuring unit preferably detects, as test parameters, an electrical direct current voltage, in particular an open-circuit voltage, of the electrochemical cell, in particular an electrical voltage between the electrical contact element of the anode-side base body and the electrical contact element of the cathode-side base body, an electrical direct current power, and / or an ohmic resistance of the electrochemical cell. For example, the measuring unit determines the electrical direct current voltage as a function of an electrical current density through the electrochemical cell. The measuring unit preferably determines the open-circuit voltage and the electrical direct current voltage at a predetermined electrical current density.

[0020] The measuring unit preferably carries out at least one alternating current measurement using the electrical unit to determine the test parameter. In particular, the electrical unit applies an alternating voltage to the electrochemical cell during the alternating current measurement, wherein the measuring unit preferably detects the test parameter at several different values ​​of a frequency of the alternating voltage. Particularly preferably, the measuring unit performs electrochemical impedance spectroscopy to detect the test parameter. Preferably, the fluid supply unit supplies the electrochemical cell with a hydrogen-containing test fluid and an oxygen-containing test fluid during the alternating current measurement, in particular analogously to what has already been described for the direct current measurement.Preferably, in the alternating current measurement, the measuring unit detects as test parameters an impedance of the electrochemical cell, in particular an impedance of the cathode of the electrochemical cell, an impedance of the anode of the electrochemical cell and / or an impedance and / or an ohmic resistance of the electrolyte.

[0021] The measuring unit preferably carries out a leakage measurement of the electrolyte to determine the test parameter. Preferably, the fluid-conducting unit supplies the electrochemical cell with pure hydrogen through the anode-side base body and with an oxygen-containing fluid through the cathode-side base body during the leakage measurement, in particular analogously to the method described above. Preferably, the measuring unit detects an electrical voltage of the electrochemical cell during the leakage measurement. The measuring unit can output and / or store the electrical voltage directly as a test parameter and / or compare the detected electrical voltage with an electrical voltage reference value of a dense electrolyte to determine a leakage value of the electrolyte as a test parameter.The voltage reference value is preferably a theoretically determined value, in particular depending on the test temperature and / or the oxygen partial pressures at the anode and / or cathode. The voltage reference value is, for example, an open-circuit voltage of 1.2 V.

[0022] The inventive design allows for the characterization of an electrochemical cell to be carried out advantageously quickly, while simultaneously minimizing the risk of damage to the electrochemical cell and / or the test device. In particular, numerous electrochemical cells can be tested advantageously in a short period of time, for example, simultaneously with series production of the electrochemical cells. In particular, various points of the electrochemical cell can be tested advantageously.

[0023] It is further proposed that in at least one method step of the method, the electrochemical cell is brought to a test temperature at a heating rate of at least 1200 K / min. In the heating phase, the control or regulating unit preferably specifies a heating rate at which the base bodies are heated. In the measuring phase, the control or regulating unit preferably specifies a constant test temperature. In the cooling phase, the control or regulating unit preferably specifies a cooling rate at which the base bodies are cooled. Cooling of the base bodies can occur passively via heat dissipation to the environment and / or actively by flushing the fluid supply unit with a flushing fluid, in particular a protective gas, inert gas and / or air. In the cooling phase, the heating unit preferably heats the base bodies if an actual value of the cooling rate exceeds a target value or a maximum permissible value of the cooling rate.The cooling rate can be equal to or different from the heating rate. Alternatively or additionally, the electrochemical cell is heated using a laser in the test device. Alternatively or additionally, the electrochemical cell is preheated externally with a gas heated to the test temperature. The inventive design allows a measurement cycle to be carried out advantageously quickly.

[0024] It is further proposed that in at least one method step of the method, the electrochemical cell is operated with pure hydrogen in order to determine at least one test parameter of the electrochemical cell. Preferably, the electrochemical cell is operated with pure hydrogen during the leak test. The electrochemical cell can be operated with pure hydrogen, a hydrogen mixture, in particular protective gas, and / or another fuel during the direct current test and / or the alternating current test. Preferably, the control or regulating unit activates ventilation of the housing, in particular on the anode side, when pure hydrogen is used in order to prevent an explosive accumulation of escaping hydrogen on the anode-side base body and / or in the housing of the test device. The design according to the invention allows the leak test of the electrolyte to be advantageously and precisely determined.

[0025] Furthermore, it is proposed that in at least one method step of the method, the electrochemical cell is operated with a protective gas, in particular the one already mentioned, in order to determine at least one test parameter of the electrochemical cell. The electrochemical cell is preferably operated with the protective gas during the direct current measurement and / or the alternating current measurement. The protective gas preferably has a fuel content, in particular hydrogen content, methane content, ammonia content or the like, of less than 5% based on a unit volume of the protective gas. Preferably, a volume fraction of at least 95% of the protective gas is inert. For example, the protective gas comprises a noble gas, in particular argon, and / or nitrogen, as an inert component.Due to the design according to the invention, the test device can advantageously be operated safely, in particular with an advantageously small amount of additional measures, components and / or method steps.

[0026] Furthermore, the use of at least one test device according to the invention, in particular according to a method according to the invention, in a series production plant for manufacturing electrochemical cells is proposed. Positioning of the electrochemical cell in the test device is achieved, for example, by an automated movement of the electrochemical cell relative to a floor of a test device deployment location, for example, by means of a conveyor system, in particular a continuous conveyor, and / or by means of a gripper of the series production plant. Positioning of the electrochemical cell in the test device is achieved, for example, by an automated movement of the test device relative to the floor of the test device deployment location, for example, by attaching the test device to a gantry robot, to a floor-mounted vehicle system, to an overhead vehicle system of the series production plant, or the like.The electrochemical cell can be positioned in the test device, for example, using a combination of the above-mentioned options. In an alternative application, the test device can be designed for manual operation. The inventive design allows for rapid determination of the quality of the electrochemical cells, and, if defects are detected, the reject rate of the series production system can be advantageously kept low.

[0027] It is further proposed that a plurality of test devices according to the invention be operated in parallel. Preferably, a plurality of test devices according to the invention are operated on the same production line, in particular at one end of the same production line, of the series production plant in order to test a plurality of manufactured electrochemical cells in parallel. The test devices, in particular the sample holders of the test devices, can be rigidly coupled to one another, in particular for synchronous testing of a plurality of electrochemical cells, or can be movable independently of one another relative to the electrochemical cells. If the test devices, in particular the sample holders of the test devices, are movable independently of one another relative to the electrochemical cells, a test of the electrochemical cells by the test device can be carried out simultaneously, with an overlap in time, or with a time offset from one another.The inventive design advantageously minimizes the limitation of the maximum possible throughput of the series production plant due to the use of the test devices. In particular, the test device can be used in a large number of series production plants with advantageously minimal time losses.

[0028] The test device according to the invention, the method according to the invention, and / or the use according to the invention are not intended to be limited to the application and embodiment described above. In particular, the test device according to the invention, the method according to the invention, and / or the use according to the invention may, in order to fulfill a functionality described herein, have a number of individual elements, components, units, and method steps that differs from the number stated herein. Furthermore, in the value ranges specified in this disclosure, values ​​within the stated limits are also to be considered disclosed and can be used arbitrarily. Drawings

[0029] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0030] They show: Fig. 1 a schematic representation of a test device according to the invention and Fig. 2 a schematic flow diagram of a method according to the invention. Description of the embodiment

[0031] Fig. 1 shows a test device 10 for an electrochemical cell 12, in particular for a high-temperature electrochemical cell. The electrochemical cell 12 is designed, for example, as a solid oxide fuel cell, in particular as an anode-supported solid oxide fuel cell, here in particular as a solid oxide fuel cell anode-supported with a metal carrier 30. The electrochemical cell 12 preferably comprises an anode 32, a cathode 36, and an electrolyte 34 arranged therebetween, and in particular the metal carrier 30 arranged on the anode 32. The test device 10 comprises at least one measuring unit 14 for detecting at least one test parameter of the electrochemical cell 12. The test device 10 comprises at least one sample holder 16 for specifying a defined position of the electrochemical cell 12 relative to the measuring unit 14 during the detection of the test parameter.The test device 10 preferably comprises a housing 68 in which the measuring unit 14 is arranged, in particular together with the sample holder 16.

[0032] The sample holder 16 comprises at least one base body 18. The base body 18 is designed, for example, as an anode-side base body 18 for arrangement on the anode 32, in particular on the anode-side metal carrier 30. The sample holder 16 preferably comprises at least one further base body 20. The further base body 20 is designed, for example, as a cathode-side base body 20 for arrangement on the cathode 36. The base bodies 18, 20 of the sample holder 16 are made at least partially, in particular at least substantially entirely, of metal. The base bodies 18, 20 are arranged to be movable relative to one another in order to grip the electrochemical cell 12 from opposite sides. The electrochemical cell 12 is preferably intended to be arranged between the base bodies 18, 20 for detecting the test parameter. Preferably, the base bodies 18, 20, in particular both base bodies, are mounted to be movable relative to the housing 68.

[0033] The sample holder 16 has at least one contact element 24 for physical contact with the electrochemical cell 12. The contact element 24 is arranged on the anode-side base body 18. Another contact element 26 of the sample holder 16 is preferably arranged on the cathode-side base body 20. The contact elements 24, 26 preferably have a mutually facing contact surface with a maximum area of ​​0.5 cm 2The contact elements 24, 26 are preferably arranged concentrically with respect to a straight line that is at least substantially perpendicular to the contact surface. The contact elements 24, 26 are preferably designed as electrical contact elements 24, 26. The contact elements 24, 26 are designed in a net-like manner. The contact elements 24, 26 are made of platinum, gold and / or nickel. The contact elements 24, 26 are in particular a wire mesh made of platinum wires, gold wires and / or nickel wires. The base bodies 18, 20 preferably have holding surfaces 38, 39 facing one another. The contact elements 24, 26 are preferably embedded in the holding surfaces 38, 39, in particular at least substantially flush with the holding surfaces 38, 39.

[0034] The test device 10 preferably comprises an electrical unit 62. The electrical unit 62 preferably forms an electrical circuit 64 for a direct current measurement. The electrical circuit 64 preferably connects the contact elements 24, 26 to one another. The electrical circuit 64 is preferably intended to be closed by the electrochemical cell 12. The electrical circuit 64 preferably comprises a direct current and / or direct voltage source 86. The measuring unit 14 preferably comprises, in the electrical circuit 64, a sensor element for detecting an electrical voltage between the contact elements 24, 26 as a test parameter. The measuring unit 14 preferably comprises, in the electrical circuit 64, a sensor element for detecting an electrical power that is provided at or tapped off at the contact elements 24, 26 as a test parameter.The measuring unit 14 preferably comprises a sensor element in the circuit 64 for detecting an ohmic resistance connecting the contact elements 24, 26 through the electrochemical cell 12 as a test parameter.

[0035] The electrical unit 62 preferably forms a further circuit 66 for an alternating current measurement. The further circuit 66 preferably connects the contact elements 24, 26 to one another. The further circuit 66 is preferably intended to be closed by the electrochemical cell 12. The further circuit 66 preferably comprises an alternating current and / or alternating voltage source 88. The measuring unit 14 preferably comprises, in the further circuit 66, a sensor element for detecting an impedance of the anode 32 as a test parameter. The measuring unit 14 preferably comprises, in the further circuit 66, a sensor element for detecting an impedance of the cathode 36 as a test parameter. The measuring unit 14 preferably comprises, in the further circuit 66, a sensor element for detecting an ohmic resistance of the electrolyte as a test parameter.

[0036] The base bodies 18, 20 of the sample holder 16 are partially hollow to supply fluid to the electrochemical cell 12. The test device 10 preferably comprises an anode-side fluid supply unit 40 for supplying the anode 32 with at least one anode-side test fluid 42. The anode-side test fluid 42 preferably contains a fuel, in particular hydrogen. The anode-side test fluid 42 is in particular a protective gas with a fuel content of less than 5% or pure hydrogen. The anode-side fluid supply unit 40 preferably extends at least partially through the anode-side base body 18 or is formed by the base body 18.The anode-side fluid supply unit 40 preferably comprises a conduit element 46 for guiding the test fluid 42 from a source of the test fluid 42, for example, a test fluid storage container of the test device 10 or an external supply line, through the anode-side base body 18 to the anode 32. An inlet 50 of the conduit element 46 is preferably arranged on a side of the anode-side base body 18 facing away from the contact element 24. An outlet 52 of the conduit element 46 is preferably arranged on a side of the anode-side base body 18 having the contact element 24. Particularly preferably, the conduit element 46 is arranged directly on the mesh-like contact element 24, in particular concentrically therewith. The anode-side fluid supply unit 40 preferably comprises a discharge element 48 for discharging an exhaust gas 58 from the electrochemical cell 12.The exhaust gas 58 can comprise the test fluid 42 and / or a reaction product of the test fluid 42 produced by the electrochemical cell 12. An inlet 54 of the discharge element 48 is preferably arranged on a side of the anode-side base body 18 having the contact element 24, in particular in the holding surface 38. The anode-side fluid supply unit 40 preferably comprises a plurality of discharge elements 48, the inlets 54 of which are preferably arranged distributed around the outlet 52 of the conduit element 46 in the holding surface 38. An outlet 56 of the discharge element 48 is preferably arranged on a side of the anode-side base body 18 facing away from the contact element 24. The test device 10 preferably comprises a cathode-side fluid supply unit 41 designed analogously to the anode-side fluid supply unit 40 for supplying the cathode 36 with a cathode-side test fluid 44 and / or for removing a cathode-side exhaust gas 60.The cathode-side test fluid 44 preferably contains oxygen. The cathode-side test fluid 44 is, for example, atmospheric air, synthetic air, or pure oxygen.

[0037] The test device 10 comprises at least one heating unit 22 in the at least one base body 18, 20 of the sample holder 16 for setting a test temperature of the electrochemical cell 12. The heating unit 22 preferably comprises at least one anode-side electrical heating element. The anode-side electrical heating element is preferably arranged in or on the line element 46. The heating unit 22 preferably comprises at least one cathode-side heating element. The cathode-side electrical heating element is preferably arranged in or on a line element of the cathode-side fluid supply unit 41. The measuring unit 14 preferably comprises at least one temperature sensor element 72. The temperature sensor element 72 is preferably arranged in the anode-side base body 18, in particular on the contact element 24. The measuring unit 14 preferably comprises at least one additional temperature sensor element 74.The additional temperature sensor element 74 is preferably arranged in the anode-side base body 18 at a distance from the contact element 24. Alternatively or additionally, the measuring unit 14 comprises at least one temperature sensor element in the cathode-side base body 20. The test device 10 preferably comprises a control or regulating unit 70. The control or regulating unit 70 is preferably provided to adjust the heating unit 22 depending on measured values ​​of the temperature sensor elements 72, 74. The control or regulating unit 70 is preferably provided to heat the base bodies 18, 20 in a controlled manner, to maintain them at a constant temperature, and to cool them in a controlled manner.In particular, the control or regulating unit 70 is provided to limit a maximum temperature change per unit of time during the heating and / or cooling of the base bodies 18, 20 and / or to ensure a minimum temperature change per unit of time.

[0038] Fig.2 shows a flowchart of a method 28 for operating the test device 10. The method 28 preferably includes a positioning step 76. In the positioning step 76, the electrochemical cell 12 is positioned in the test device 10 between the base bodies 18, 20, preferably by a movement of the test device 10 or by a combined movement of the test device 10 and the electrochemical cell 12 relative to a floor of a location of use of the test device 10. The sample holder 16 preferably moves the base bodies 18, 20 towards each other to grip the electrochemical cell 12 in position and to establish electrical contact between the electrochemical cell 12 and the contact elements 24, 26.

[0039] The method 28 preferably includes a heating phase 78. During the heating phase 78, the heating unit 22 preferably heats the base bodies 18, 20 to a test temperature. The test temperature is preferably greater than 500°C.

[0040] The electrochemical cell 12 is heated to the test temperature by the heating unit 22 at a heating rate of at least 1200 K / min. During the heating phase 78, the fluid supply units 40, 41 preferably supply the electrochemical cell 12 with an inert fluid, in particular nitrogen and / or a noble gas, or with the test fluid 42, 44.

[0041] The method 28 preferably comprises a measuring phase 80. The control or regulating unit 70 preferably keeps the test temperature constant during the measuring phase 80. The measuring phase 80 preferably comprises a leak test. During the leak test, the anode 32 is operated with pure hydrogen in order to determine at least one test parameter of the electrochemical cell 12. During the leak test, the measuring unit 14 preferably determines the electrical voltage in the circuit 64 for direct current measurement as a test parameter. The measuring phase 80 preferably comprises a direct current measurement. During the direct current measurement, the measuring unit 14 preferably determines a voltage-current density curve of the electrochemical cell 12 using the circuit 64 for direct current measurement. The measuring phase 80 preferably comprises an alternating current measurement.During the alternating current measurement, the measuring unit 14 preferably performs electrochemical impedance spectroscopy using the alternating current measurement circuit 66. During the direct current measurement and / or the alternating current measurement, the anode 32 is preferably operated with a protective gas to determine at least one test parameter of the electrochemical cell 12.

[0042] The method 28 preferably includes a cooling phase 82. During the cooling phase 82, the base bodies 18, 20 are cooled passively or actively. When the temperature falls below a threshold value, the sample holder 16 preferably detaches the base bodies 18, 20 from the electrochemical cell 12 and waits for the next electrochemical cell to be positioned between the base bodies 18, 20.

Claims

[1] Test device (10) for an electrochemical cell (12), in particular for an electrochemical high-temperature cell, with at least one measuring unit (14) for detecting at least one test parameter of the electrochemical cell (12) and with at least one sample holder (16) for specifying a defined position of the electrochemical cell (12) relative to the measuring unit (14) during the detection of the test parameter, characterized by that at least one base body (18, 20) of the sample holder (16) is made at least partially, in particular at least substantially completely, of metal and / or ceramic. [2] Test device (10) according to claim 1, characterized by at least one heating unit (22) in the at least one base body (18, 20) of the sample holder (16) for setting a test temperature of the electrochemical cell (12). [3] Test device (10) according to claim 1 or 2, characterized bythat the at least one base body (18, 20) of the sample holder (16) is partially hollow to supply fluid to the electrochemical cell (12). [4] Test device (10) according to one of the preceding claims, characterized by that the sample holder (16) comprises at least one contact element (24, 26) for physical contact with the electrochemical cell (12), which has a maximum surface area of ​​0.5 cm 2 has. [5] Test device (10) according to one of the preceding claims, characterized by that the sample holder (16) comprises at least one electrical contact element (24, 26) arranged on the at least one base body (18, 20) for electrical contact with the electrochemical cell (12), which is designed in a net-like manner. [6] Test device (10) according to one of the preceding claims, characterized bythat the sample holder (16) comprises at least one electrical contact element (24, 26) arranged on the at least one base body (18, 20) for electrical contact with the electrochemical cell (12), which is made of platinum, nickel or gold. [7] Method (28) for operating a test device (10) according to one of claims 1 to 6. [8] Method (28) according to claim 7, characterized by that in at least one method step the electrochemical cell (12) is brought to a test temperature at a heating rate of at least 1200 K / min. [9] Method (28) according to claim 7 or 8, characterized by that in at least one method step the electrochemical cell (12) is operated with pure hydrogen in order to determine at least one test parameter of the electrochemical cell (12). [10] Method (28) according to one of claims 7 to 9, characterized bythat in at least one method step the electrochemical cell (12) is operated with a protective gas in order to determine at least one test parameter of the electrochemical cell (12). [11] Use of at least one test device (10) according to one of claims 1 to 6, in particular according to a method (28) according to one of claims 7 to 10, in a series production plant for the production of electrochemical cells (12). [12] Use according to claim 11, characterized by that several test devices (10) according to one of claims 1 to 6 are operated in parallel.

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