Device and system for heating an energy storage device and vehicle

Abstract

Device (1) for heating an electrochemical energy storage device (2) with a fluid electrolyte, in particular a lithium-ion cell or a redox flow cell, wherein the device (1) has a fluid line (4) which fluidly connects a fluid outlet (2a) of the electrochemical energy storage device (2), through which the fluid electrolyte can be discharged from the electrochemical energy storage device (2), with a fluid inlet (2b) of the electrochemical energy storage device (2), through which the fluid electrolyte can be supplied to the electrochemical energy storage device (2), in the form of a circuit, wherein the fluid line (4) is made of an inductively heatable material and is configured to transfer inductively generated heat to the fluid electrolyte and to generate convection of the fluid electrolyte.

Description

The invention relates to a device and a system for heating an electrochemical energy storage device, in particular a lithium-ion cell or a redox flow cell, and to a vehicle, in particular a motor vehicle, with such a device. To supply electrically powered vehicles, especially passenger cars, with the necessary energy, electrochemical energy storage devices are usually provided in the vehicles. DE 10 2010 041 017 A1 relates to an electrochemical energy storage device comprising a cell with an anode, a cathode, and a fluid electrolyte that enables current flow from the anode to the cathode. Two openings are provided, the openings being connected by a linkage for the circulating circulation of the electrolyte. In general, these electrochemical energy storage devices have an operating temperature range in which the performance of the energy storage devices is highest and the capacity of the energy storage devices remains essentially constant even during a series of charging and discharging processes. To enable efficient and gentle operation of energy storage devices, charge is typically extracted from the energy storage system and used to heat the device before operation, i.e., before discharging or charging. For this purpose, an ohmic heating element can be integrated into the energy storage device or positioned within its area, allowing the energy storage device to be heated to a predetermined or required temperature. From DE 10 2011 002 729 A1, an energy storage arrangement is known which comprises an electrical energy storage unit with two electrodes and an electrolyte arranged between the electrodes. An induction heating device is provided which interacts with the energy storage unit or parts thereof, wherein the energy storage unit or parts thereof can be heated via the induction heating device. DE 10 2014 208 044 A1 relates to a metal-air battery with a housing containing a hollow cylindrical cathode arranged within the housing between an air space and an electrolyte space, and a metallic anode located in the electrolyte space. Heat transfer between a conversion device, such as a fuel cell, and the rest of the metal-air battery can occur, for example, by means of a heat exchanger that is suitably integrated into the electrolyte circuit. It is an object of the invention to provide an alternative heating process for heating an electrochemical energy storage device, in particular to further improve the heating of an electrochemical energy storage device. This problem is solved by a device and a system for heating an electrochemical energy storage device according to the independent claims, as well as a vehicle with such a system. A first aspect of the invention relates to a device for heating an electrochemical energy storage device, in particular a lithium-ion cell or a redox flow cell, with a fluid electrolyte. A fluid line of the device connects an electrolyte outlet of the electrochemical energy storage device, from which the electrolyte can be discharged, to an electrolyte inlet of the electrochemical energy storage device, through which the electrolyte can be supplied, in a fluid-conducting manner in the form of a circuit. The fluid line is preferably made of an inductively heatable material and is configured to transfer inductively generated heat to the electrolyte and to promote, in particular generate, convection of the electrolyte. A second aspect of the invention relates to a system for heating at least one electrochemical energy storage device, in particular a lithium-ion cell or a redox flow cell, comprising at least one electrochemical energy storage device with a fluid electrolyte, at least one device for heating an electrochemical energy storage device according to the first aspect of the invention, wherein the at least one device is coupled to the at least one electrochemical energy storage device, and an induction device which is configured to generate an external magnetic field by which the fluid line of the at least one device can be inductively heated. A third aspect of the invention relates to a vehicle, in particular a motor vehicle, with an electrochemical energy storage device, in particular a lithium-ion cell or a redox flow cell, and a device according to the first aspect of the invention. For the purposes of the invention, an electrochemical energy storage device can also be understood to be an energy storage module comprising several galvanic cells. The galvanic cells preferably use alkali and alkaline earth metal ions as charge carriers. Examples of electrochemical energy storage devices are lithium, sodium, potassium, magnesium, or aluminum ion cells, or redox flow cells, in which transition, alkali, and / or earth metal ions are used as charge carriers. Fluid in the sense of the invention means liquid or gaseous. The features and advantages described below with regard to the first aspect of the invention and its advantageous embodiment also apply, at least where technically appropriate, to the second and third aspects of the invention and their advantageous embodiment, and vice versa. The invention is based in particular on the approach of bringing an electrochemical energy storage device with a liquid electrolyte to a predetermined operating temperature by heating the liquid electrolyte in a fluid line outside the energy storage device. The electrolyte in the fluid line is preferably heated by heat transfer from the fluid line, which is made of an inductively heatable material, so that at least a portion of the fluid line can be heated inductively. Simultaneously, the inductive heating of the fluid line promotes, and in particular drives, convection of the electrolyte. The fluid line preferably forms an electrolyte circuit, particularly a closed one, with the electrochemical energy storage device. For this purpose, the fluid line is connected to the energy storage device at an electrolyte outlet, through which the electrolyte can flow from the energy storage device into the fluid line, and at an electrolyte inlet, through which the electrolyte can flow back from the fluid line into the energy storage device. Heating at least a portion of the electrolyte in at least a portion of the fluid line leads to a reduction in the electrolyte's density in that portion, causing it to rise. This initiates a natural convection current, drawing the heated electrolyte from the fluid line through the electrolyte inlet into the electrochemical energy storage device and heating it. In this sense, the inductively heated fluid line can be considered a pump, in particular a convection pump. This allows the electrochemical energy storage device to be brought to a predetermined operating temperature at which it can be operated efficiently and gently. Furthermore, the electrochemical energy storage device can be heated wirelessly from an external source, i.e., without drawing energy from the device itself. This can, for example, improve the performance of electrochemical energy storage devices in electrically powered vehicles in cold climates. In particular, this avoids the need to activate the electrochemical energy storage device for heating and / or operating it in an energy-consuming standby mode, where energy can be drawn from the electrochemical energy storage device at any time to heat it. This saves the energy stored in the electrochemical energy storage device and increases its lifespan. Overall, the invention enables improved heating of an electrochemical energy storage device, by transporting heat directly into the interior of the electrochemical energy storage device via the electrolyte. In a preferred embodiment, the device further comprises a turbulence device which is designed to turbulence the fluid electrolyte of the electrochemical energy storage device in the fluid line. In the context of the invention, "turbulence" means the promotion, in particular the generation, of turbulence. Preferably, when an alternating magnetic field, particularly an external one, is applied, heat is generated in at least a portion of the fluid line, which is then transferred to the electrolyte within that portion. The transfer of heat from the fluid line to the electrolyte can be enhanced by the turbulence device, which also promotes electrolyte convection. The turbulence device therefore enables particularly efficient and reliable heating of the electrolyte and thus of the electrochemical energy storage device. In a further preferred embodiment, the swirling device comprises at least one swirling element which is arranged in the fluid line and can be operated inductively, i.e., by applying an external magnetic field, such that the fluid electrolyte of the electrochemical energy storage device is swirled in the fluid line. This allows for a particularly reliable heat transfer from the fluid line to the electrolyte. In the context of the invention, an inductive operation of a vortex element is understood to mean a vortex element that can be operated, and in particular driven, by an external magnetic field, in particular an alternating magnetic field or a rotating magnetic field. For this purpose, the external magnetic field can induce a magnetic moment in the vortex element, which aligns itself with the external magnetic field. By changing the orientation of the external magnetic field, in particular by rotating the magnetic field, the vortex element can thus be moved, and in particular set into rotation. In a further preferred embodiment, the at least one vortex element is configured to convey the fluid electrolyte of the electrochemical energy storage device through the fluid conduit as the at least one vortex element moves along a predetermined direction of movement, wherein the predetermined direction of movement coincides with a convection direction of the fluid electrolyte of the electrochemical energy storage device. In particular, the at least one vortex element is configured to promote the natural convection of the electrolyte caused by changes in its density. This enables particularly reliable convection of the electrolyte and particularly reliable heating of the electrochemical energy storage device. The vortex element preferably serves as a pump, or at least as part of a pump, through which the electrolyte is pumped through the circuit formed by the electrochemical energy storage device and the fluid line. This allows the heating of the energy storage device to be accelerated. In a further preferred embodiment, the at least one vortex element is at least partially magnetizable. This allows it to be reliably set in motion by applying an alternating magnetic field, particularly an external one, without requiring a mechanical connection to a drive, such as an electric motor. The external actuation of the at least one vortex element allows the energy storage device to be completely switched off when not in use, since no energy needs to be drawn from the energy storage device itself to actuate the at least one vortex element for heating before commissioning. In particular, the energy storage device does not need to be operated in a so-called standby mode, in which energy is continuously drawn from it. In a further preferred embodiment, the at least one vortex element is substantially circular along at least one circumference. Preferably, the at least one vortex element is substantially spherical. This allows the electrolyte to easily flow around it without impeding the convection motion of the electrolyte. Furthermore, the at least one vortex element can thus also be driven by a weak alternating magnetic field, since its flow resistance when moving in the fluid electrolyte is particularly low. Preferably, the at least one vortex element is rotationally symmetrical with respect to an axis of rotation and is preferably arranged to rotate within the fluid line with respect to this axis of rotation. The axis of rotation can be perpendicular to the fluid line. This allows the vortex element to be arranged essentially centrally within the fluid line, enabling effective interaction with the electrolyte flowing through the fluid line. In a further preferred embodiment, the at least one vortex element comprises one or more vanes configured to swirl the fluid electrolyte of the electrochemical energy storage device in the fluid line when the at least one vortex element moves and / or to convey it along the direction of movement through the fluid line. Preferably, the one or more vanes are evenly distributed around the circumference of the at least one vortex element. Furthermore, the one or more vanes are preferably curved such that, during inductively generated movement of the at least one vortex element, the at least one vane conveys a larger proportion of the electrolyte along the direction of movement than against the direction of movement. In a further preferred embodiment, at least part of the vortex generator is made of iron or an iron alloy. This allows the part of the vortex generator to be magnetized by applying an external magnetic field and to be reliably set into rotation when the external magnetic field is rotated. In a further preferred embodiment, at least part of the fluid line is made of copper. Copper is preferably chemically inert with respect to the electrolyte flowing through the fluid line and can be easily heated inductively. In a further preferred embodiment, the induction device is designed as a Halbach array. The individual elements of the Halbach array are preferably formed by electromagnets, in particular coils. The Halbach array allows, on the one hand, a concentration of the magnetic flux on one side of the induction device and, on the other hand, a planar design of the induction device, so that, firstly, a fluid line magnetically coupled to the induction device can be heated efficiently, and secondly, several fluid lines distributed over the area of ​​the induction device can be heated simultaneously. Further features, advantages, and applications of the invention will become apparent from the following description in conjunction with the figures, in which the same reference numerals are used throughout for the same or corresponding elements of the invention. The figures show, at least partially schematically: Fig. 1 a preferred embodiment of a system for heating at least one electrochemical energy storage device; and Fig. 2 a part of a preferred embodiment of a device for heating an electrochemical energy storage device. Fig. 1 shows an embodiment of a system 100 for heating at least one electrochemical energy storage device 2, comprising an electrochemical energy storage device 2, a device 1 for heating at least one electrochemical energy storage device 2, and an induction device 3. The device 1 for heating at least one electrochemical energy storage device 2 has a fluid line 4 through which a fluid electrolyte from the energy storage device 2 can flow. For this purpose, the fluid line 4 is preferably connected to a fluid outlet 2a of the energy storage device 2 and a fluid inlet 2b of the energy storage device 2. This allows the fluid electrolyte from the energy storage device 2 to flow through the fluid outlet 2a into the fluid line 4 and from there back into the energy storage device 2 through the fluid inlet 2b. In other words, the electrochemical energy storage device 2 and the device 1, in particular the fluid line 4, form a circuit for the fluid electrolyte of the energy storage device 2. This is indicated by the dashed arrows. The fluid line 4 is preferably made of an inductively heatable material, in particular copper. This makes it possible to generate heat in the fluid line 4 without contact by applying an external magnetic field 5, in particular an alternating magnetic field or a rotating magnetic field. The heat generated in fluid line 4 can be transferred to the electrolyte in fluid line 4. Heating the electrolyte preferably induces convection along the direction of movement 6 indicated by the dashed arrows, allowing the heated electrolyte in fluid line 4 to flow into the interior of the energy storage device 2 and thereby bring it to a predetermined operating temperature. The electrolyte, which cools down in the process, can then flow back into fluid line 4 through electrolyte outlet 2a, where it is preferably reheated. The convection motion driven by the external magnetic field 5 enables the device 1, in particular the fluid line 4, to function both as a heater and as a pump. By means of this arrangement, shown in Fig. 1, at least a cooler portion of the electrolyte in the energy storage device 2 can be heated externally, i.e., outside the energy storage device 2, and supplied to the initially cooler energy storage device 2 in its heated state, while another cooler portion of the electrolyte flows out of the energy storage device 2 into the fluid line 4, where it can also be heated. If this process is repeated over several cycles, the temperature of the energy storage device 2 can rise to a predetermined operating temperature. The external magnetic field 5 is generated by the induction device 3. For this purpose, the induction device 3 can have one or more coil arrangements 3a, which are preferably controlled by a control device 7 of the induction device 3 such that the generated external magnetic field 5 inductively heats the fluid line 4. The control unit 7 can also be connected to a temperature sensor 8, which is configured to detect the temperature of the energy storage device 2. Based on the detected temperature, the control unit 7 can determine whether the temperature of the energy storage device 2 has reached or exceeded a predetermined operating temperature. In particular, the control unit 7 can control the coil devices 3a depending on the detected temperature of the energy storage device 2, so that the energy storage device 2 can be reliably heated to the operating temperature. The induction device 3 is preferably designed as a so-called Halbach array. In particular, the coil arrangements 3a are arranged and / or controlled by the control device 7 in such a way that they form a Halbach array or act as a Halbach array. In the Halbach array, the magnetic moments of the coil devices 3a are arranged such that a magnetic flux forming the external magnetic field 5 runs essentially on only one side of the induction device 3, in particular on a side facing the device 1, for example by tilting the magnetic poles of adjacent coil devices 3a essentially by 90° relative to each other. Preferably, the induction device 3 is designed as a planar unit, so that several devices 1, in particular several vehicles with an energy storage device 2 and a device 1 for heating the respective energy storage device 2, can be arranged next to each other within the area formed by the induction device 3 and the devices 1 can be supplied simultaneously with magnetic energy via the generated external magnetic field 5 for heating the respective electrolyte and generating the convection motion. Fig. 2 shows part of a preferred embodiment of a device 1 for heating an electrochemical energy storage device 2, which has a fluid line 4 and a turbulence device 9. As described above in connection with Fig. 1, the fluid line 4 serves to heat a fluid electrolyte flowing through the energy storage device 2 by inductively heating the fluid line 4. The turbulence device 9 comprises several turbulence elements 10 arranged in the fluid line 4, which are configured to turbulence the electrolyte, particularly the flowing electrolyte, within the fluid line 4. Specifically, the turbulence elements 10 are configured to promote, and in particular generate, turbulence or a turbulent flow in the fluid line 4, at least in a region of the fluid line 4 where the turbulence elements 10 are located. The turbulence elements 10 are preferably arranged substantially along a centerline of the fluid line 4, i.e., a line passing through the centers of several cross-sections of the fluid line 4. Turbulence or eddies in the fluid electrolyte within fluid line 4 can increase the heat transfer from fluid line 4 to the electrolyte. This enables increased efficiency of the device 1. The vortex elements 10 are preferably designed as substantially circular or spherical vortex elements 10, each rotatably mounted about an axis of rotation 10a. The axes of rotation 10a are substantially perpendicular to a direction of movement 6 of the electrolyte. The vortex elements 10 can further be made of a magnetizable material, for example iron or an iron alloy, so that they can be inductively set in motion, in particular into rotation. Preferably, the vortex elements 10 are configured to be magnetized by an external magnetic field 5, wherein the magnetic moments formed in the vortex elements 10 align themselves in the external magnetic field 5. If the orientation of the external magnetic field 5 changes, for example, if the external magnetic field 5 is designed as an alternating magnetic field or a rotating magnetic field, the magnetic moments of the vortex elements 10 follow the direction determined by the magnetic field 5. The movement or rotation of the vortex elements 10 generated thereby vortexes the electrolyte in the fluid line 4 particularly reliably. Preferably, the vortex elements 10 are magnetizable by the external magnetic field 5, in particular an alternating magnetic field or a rotating magnetic field, which induces a current in the fluid line 4 that is converted into heat resistively, i.e., through an internal resistance of the fluid line 4. This allows the electrolyte to be heated, set into convection motion, and vortexed by applying a single external magnetic field 5. To further enhance the effect of the turbulence elements 10 on the electrolyte, the turbulence elements 10 can each have one or more vanes 11, which are preferably evenly distributed along a circumference of the turbulence elements 10, in particular perpendicular to the axis of rotation 10a. Preferably, the vanes 11 have a curved shape, which further intensifies the turbulence of the electrolyte when the vanes 11 move. Additionally, the electrolyte can also be conveyed through the fluid line 4 by means of the curved impeller blades 11 when the impeller blades 11 are moving, particularly along the direction of movement 6 determined by the convection motion. The inductively set-in-motion vortex elements 10 can thus further promote, and in particular support, the convection motion promoted, and in particular generated, by the heating of the electrolyte. Preferably, the convection motion promoted by the heating of the electrolyte is intensified by the inductively generated movement of the vortex elements 10. Reference symbol list 1 Device 2 Electrochemical energy storage device 2a Fluid outlet 2b Fluid inlet 3 Induction device 3a Coil assembly 4 Fluid line 5 External magnetic field 6 Direction of movement 7 Control device 8 Temperature sensor 9 Vortexing device 10 Vortexing element 10a Axis of rotation 11 Blade 100 System

Claims

Device (1) for heating an electrochemical energy storage device (2) with a fluid electrolyte, in particular a lithium-ion cell or a redox flow cell, wherein the device (1) has a fluid line (4) which fluidly connects a fluid outlet (2a) of the electrochemical energy storage device (2), through which the fluid electrolyte can be discharged from the electrochemical energy storage device (2), with a fluid inlet (2b) of the electrochemical energy storage device (2), through which the fluid electrolyte can be supplied to the electrochemical energy storage device (2), in the form of a circuit, wherein the fluid line (4) is made of an inductively heatable material and is configured to transfer inductively generated heat to the fluid electrolyte and to generate convection of the fluid electrolyte. Device (1) according to claim 1, further comprising a swirling device (9) which is configured to swirl the fluid electrolyte of the electrochemical energy storage device (2) in the fluid line (4). Device (1) according to claim 2, wherein the swirling device (9) has at least one swirling element (10) which is arranged in the fluid line (4) and is inductively operable, in particular inductively movable in such a way that the fluid electrolyte of the electrochemical energy storage device (2) is swirled in the fluid line (4). Device (1) according to claim 3, wherein the at least one vortex element (10) is configured to convey the fluid electrolyte of the electrochemical energy storage device (2) through the fluid line (4) when the at least one vortex element (10) moves along a predetermined direction of movement (6), wherein the predetermined direction of movement (6) corresponds to a convection direction of movement of the fluid electrolyte of the electrochemical energy storage device (2). Device (1) according to one of claims 3 or 4, wherein the at least one vortex element (10) is magnetizable. Device (1) according to one of claims 3 to 5, wherein the at least one vortex element (10) is circular along at least one circumference. Device (1) according to one of claims 3 to 6, wherein the at least one vortex element (10) has one or more vanes (11) which are arranged to swirl the fluid electrolyte of the electrochemical energy storage device (2) in the fluid line (4) when the at least one vortex element (10) is moved and / or to convey it along the direction of movement (6) through the fluid line (4). Device (1) according to one of claims 2 to 7, wherein at least a part of the turbulence device (9) is made of iron or an iron alloy. Device (1) according to one of the preceding claims, wherein at least a part of the fluid line (4) is made of copper. System (100) for heating at least one electrochemical energy storage device (2), in particular at least one lithium-ion cell or one redox flow cell, comprising: - at least one electrochemical energy storage device (2) with a fluid electrolyte; - at least one device (1) for heating an electrochemical energy storage device (2) according to one of claims 1 to 9, wherein the at least one device (1) is coupled to the at least one electrochemical energy storage device (2); and - an induction device (3) which is configured to generate an external magnetic field (5) by which the fluid line (4) of the at least one device (1) can be inductively heated. System (100) according to claim 10, wherein the induction device (3) is configured as a Halbach array. Vehicle, in particular motor vehicle, with an electrochemical energy storage device (2), in particular a lithium-ion cell or a redox flow cell, and a device (1) for heating the electrochemical energy storage device (2) according to one of claims 1 to 9.

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