Device and method for cooling a battery cell as well as battery module, battery, battery system and vehicle

Abstract

Device (310) for cooling a battery cell (1001, 1002) comprising: - means (312) for receiving (420) measured values of the battery cell (1001, 1002); - means (312) for determining (430) a temperature value of the battery cell (1001, 1002) from the received measured values; - means (312) for comparing (440) the determined temperature value with a predetermined temperature threshold value for the battery cell (1001, 1002); and - means (312) for setting (460), when the determined temperature value exceeds the predetermined temperature threshold value, a determined current value for the battery cell (1001, 1002) or another battery cell (1002, 1001) arranged adjacent to the battery cell (1001, 1002), such that a current (I1, I2) through the battery cell (1001, 1002) at the level of the determined current value causes a reduction in the temperature of the battery cell (1001, 1002) or the other battery cell (1002, 1001), further comprising - means (312) for selecting, before setting (460) the determined current value, the battery cell (1001, 1002) or the other battery cell (1002, 1001) from a plurality of battery cells (1001, 1002).

Description

The invention relates to a device for cooling a battery cell and to a battery module, a battery and a battery system, each comprising such a device. It additionally relates to a vehicle and a method for cooling a battery cell.Prior ArtIt is foreseeable that new battery systems, for example with lithium-ion batteries, will increasingly be used as rechargeable electrical energy stores (EES), both in stationary applications, for example in wind power installations, and in mobile applications, for example in electric vehicles (EV), hybrid vehicles (HEV) or plug-in hybrid electric vehicles (PHEV).The battery systems must meet very high requirements with respect to usable energy content, charging / discharging efficiency, reliability, lifetime and tolerable capacity loss, for example, due to frequent partial discharge. High-power or high-energy battery cells are thus used in specific designs and designs. For example, the battery cells may comprise a prismatic housing comprising aluminum, an aluminum alloy or stainless steel.A battery system includes a plurality of battery cells. Due to their cell internal resistance and electrochemical processes taking place, the battery cells warm up during charging and discharging. The battery cells may be connected in series (series) to increase the electrical voltage and / or connected in parallel to increase the maximum electrical current. The battery cells can be combined to form battery units or battery modules. When used to drive vehicles, for example, approximately 100 battery cells (as a traction battery) can be connected in series or in parallel. In a high-voltage battery system, the total voltage can thus be 450 V, for example.The temperature range permissible for the operation of the battery cells is typically between +5 ° C. and +40 ° C. In the lower range of the operating temperature, the performance of the battery cells may decrease significantly. At temperatures below approximately 0° C., the internal resistance of the battery cells rises sharply, and the performance and the efficiency of the battery cells decrease continuously with continuing falling temperatures. Irreversible damage to the battery cells can also occur in this case. Even if the operating temperature is exceeded, the performance of the battery cells may decrease significantly. At temperatures above about 40° C., the service life of the battery cells is reduced, regardless of whether the thermal energy in the battery cells is released or supplied from the outside. This can likewise lead to irreversible damage to the battery cells. The damage can lead to an accelerated aging of the battery cells or a self-sustaining exothermic reaction (thermal runaway) of the battery cells, which can lead, for example, to cell burn or cell explosion and thus represents a risk for humans and the environment.In order to ensure the safety, reliability and service life of the battery module or battery system, it is therefore necessary to operate the battery cells within the predefined specification. For this purpose, the battery cells are usually monitored with respect to temperature, voltage, current, capacitance resulting therefrom and / or internal resistance by means of a central control device or regulating device such as a battery management system (BMS), in order to be able to identify or avoid a critical or dangerous situation in good time. As a result, the battery module or battery system can be completely switched off, for example in the event of a fault.M. Shadedman Rad, D. L. Danilov, M. Baghala, M. Kazemeini, P. H. L. Notten, "Adaptive thermal modeling of Lithium-ion batteries", Electrochimica Acta 102 (2013), pages 183-195, discloses adaptive thermal modeling of lithium-ion batteries on the basis of a small cell of radial design having a rated capacity of 7.5 Ah.Furthermore, WO 2012 / 019 062 A2 discloses a rechargeable battery having battery cells and a current limiter such as a temperature-dependent resistor or a fuse for limiting or interrupting a current flowing through the battery cells if the current exceeds a predetermined current and / or a temperature of one of the battery cells exceeds a predetermined temperature.The object of the present invention is to further increase the safety, reliability and life of batteries (batteries) and battery systems (battery systems), wherein it is necessary to further improve the cooling of battery cells.The prior art for this purpose is also the documents DE 10 2013 204 532 A1 and US 2009 / 0 315 403 A1.Disclosure of the InventionThis object is achieved by the devices and methods according to the invention having the features of the independent claims, which have the advantage that overheating of a battery cell can be prevented or at least slowed down. In this case, an endothermic reaction due to an entropic heat consumption (entropic heat consumption) in the battery cell and / or another adjacently arranged battery cell or a multiplicity of adjacently arranged battery cells can be used in order to absorb and store heat and thus to cool the battery cell. As a result, it is possible to prevent or at least delay the permissible temperature range from being exceeded. Thus, the risk of thermal runaway can be reduced. As a result, the safety of the battery cell can be increased both during its operation, for example during charging and / or discharging, and also during non-operation (rest), for example during production, storage and / or transport.Advantageous embodiments of the present invention are described in the dependent claims.Expediently, the apparatus can also comprise a device for preprocessing, for example filtering, the received measured values. As a result, an interference signal, which may be contained in the measurement values, can be removed. Thus, the quality and accuracy of cooling can be improved.Conveniently, the apparatus may comprise means for interrupting, prior to adjusting the determined current value, the current through the battery cell. As a result, the current value can be determined and adjusted in magnitude and direction independently of the current which has previously flowed through the battery cell. Thus, a cooling effect can be obtained.According to the invention, the device comprises a device for selecting, before the setting of the determined current value, the battery cell or the other battery cell from a plurality of battery cells. As a result, a battery cell or a plurality of battery cells having a state of charge which allows the absorption of the greatest amount of heat can be selected. Thus, one or more battery cells of the plurality of battery cells may be better cooled.Expediently, a received measured value can comprise a temperature measured value or the received measured values can comprise temperature measured values. As a result, the temperature of the battery cell can be determined directly, for example by means of a temperature sensor which is arranged locally on or in the battery cell. Thus, the determination can be simplified.Expediently, the received measured values can comprise voltage measured values and current measured values. The temperature of the battery cell can be calculated from the voltage measurement values and current measurement values. Thus, the voltage measurement values and current measurement values, which are determined for other purposes, for example, can be used for determining the temperature. In such an implementation, a temperature sensor which is associated with the battery cell can be dispensed with.Expediently, the setting of the specific current value can comprise an impression of the specific current value on the current. As a result, the current value in height and direction can be freely determined and adjusted. Thus, the current value may be set, for example, taking into account a current factor and / or a state of charge (SoC), such that the effect of the endothermic reaction due to an entropic heat consumption may be maximized. Thus, the battery cell can be cooled more easily.Expediently, the setting of the specific current value can comprise reducing or limiting the current, i.e. the operating current, for example charging current or discharging current, to the specific current value.Expediently, the set current value can cause a discharge of the battery cell or of the other battery cell. As a result, the state of charge of the battery cell can be reduced. For this purpose, resistors, semiconductors or battery cells can be used as current sinks, for example. By discharging an adjacent battery cell while simultaneously charging a further adjacent battery cell, losses can be minimized and / or the effect of the endothermic reaction can be maximized.Expediently, the set current value can be a clocked current value or a pulse width modulated (PVM) current value. In this embodiment, the set current can be switched on or off in a clocked manner.Expediently, the set current value can correspond to a current factor of the battery cell or of the other battery cell in the range from 0.1 C. to 0.5 C., for example 0.2 C. As a result, the endothermic reaction can be utilized better.Expediently, a state of charge (SoC) of the battery cell or of the other battery cell can be in the range from 0% to 50%, for example 25%. As a result, the endothermic reaction can be utilized better.Other values for the discharge current and / or SoC of the battery cell may be expedient for realizing the method.The invention further provides a battery module comprising the device described above.The invention further provides a battery comprising the above-described device or the above-described battery module.The invention further provides a battery system comprising the above-described device, the above-described battery module or the above-described battery.The invention furthermore provides a vehicle, in particular a motor vehicle such as an electric motor vehicle, hybrid vehicle, plug-in hybrid vehicle or electric motor bicycle (electric bike, e-bike), electric bicycle (pedal electric cycle, pedelec), a marine vehicle such as an electric boat or submarine (submarine), an aircraft or a spacecraft, which comprises the above-described device connected to the vehicle, the above-described battery module connected to the vehicle, the above-described battery connected to the vehicle or the above-described battery system connected to the vehicle.Expediently, the method can comprise preprocessing, for example filtering the received measured values. As a result, an interference signal, which may be contained in the measurement values, can be removed. Thus, the quality and accuracy of cooling can be improved.Expediently, the method can furthermore comprise, before the setting of the determined current value, interrupting the current through the battery cell. As a result, the current value can be determined and adjusted in magnitude and direction independently of the current which has previously flowed through the battery cell. Thus, the battery cell can be cooled more easily.According to the invention, the method further comprises, before the setting of the determined current value, selecting the battery cell or the other battery cell from a plurality of battery cells. As a result, a battery cell or a plurality of battery cells having a state of charge which allows the absorption of the greatest amount of heat can be selected. Thus, the battery cell can be cooled more easily.Furthermore, a computer program can be provided which is stored on a data carrier or in a memory of a computer and which comprises instructions readable by the computer which are intended to execute one of the previously described methods when the instructions are executed on the computer.Furthermore, a computer program product can be provided which comprises the computer program described above.It is within the scope of the invention to not necessarily carry out the method steps in the described sequence. In a further embodiment, the method steps can also be interleaved (interleaving).Furthermore, it is possible that individual sections of the described method can be formed as individual saleable units and remaining sections of the method can be formed as other saleable units. The method according to the invention can thus be executed as a distributed system on different computer-based entities, for example client-server entities. It is thus possible, for example, for one module to comprise different sub-modules for its part.Further features and advantages of the present invention will become apparent to a person skilled in the art from the following description of exemplary embodiments, which, however, should not be interpreted as limiting the invention, with reference to the attached drawings. FIG. 1 shows a schematic view of a battery system having a plurality of battery cells and a device for cooling the battery cells according to an embodiment of the invention, FIG. 2 shows a schematic view of a method for cooling battery cells according to another embodiment of the invention, and FIG. 3 shows exemplary temperature profiles of a battery cell as a function of an amount of charge drawn from the battery cell.The plurality of battery cells 100 1, 1002 is arranged in a battery module 200, wherein the battery cells 100 1, 1002 in the battery module 200 are arranged spatially adjacent to one another or next to one another, such that they are thermally connected to one another. The battery cells 100 1, 1002 each include electrical terminals 110 1, 1102, 1201, 1202 for electrically connecting the battery cells 100 1, 1002 to a load device (not shown in FIG. 1 ). The battery cells 100 1, 1002 can be electrically connected to one another in series or in parallel, for example.The apparatus 310 comprises a processing device 312, which can be designed, for example, as a processor, microprocessor or microcontroller, for program-controlled processing of measurement values, determination of temperature values and current values of the battery cells 100 1, 1002, a storage device 314, which is connected to the processing device 312 and can be designed, for example, as a memory such as nonvolatile memory and / or volatile memory, for storing commands and / or data such as measurement values, threshold values and / or control values, and a connection device 316, which is connected to the processing device 312 and can be designed, for example, as an interface, for transmitting data. The device 310 may be integrated in the battery module 200. The apparatus 310 may be implemented by a battery management system. Alternatively, the device 310 may be implemented by a remote computer, for example a central server. In this case, the data can be transmitted, for example, via the Internet or wirelessly.The apparatus 310 may further comprise temperature measuring devices 320 1, 3202 such as temperature sensors, which are each thermally connected to the battery cells 100 1, 1002 and are electrically connected to the connecting device 316 via connections such as connecting lines 325 1, 3252 for detecting or measuring a temperature of one of the battery cells 100 1, 1002 respectively.The apparatus 310 may further comprise a voltage measurement device, which is electrically connected to the connection device 316, for detecting or measuring a voltage of one of the battery cells 100 1, 1002, which is connected between the electrical terminals 110 1, 1102, 1201, 1202, and / or a current measurement device, which is electrically connected to the connection device 316, for detecting or measuring a current I 1, I 2 through one of the battery cells 100 1, 1002 respectively.The apparatus 310 may further comprise adjusting devices 330 1, 3302, which are electrically connected to the connecting device 316 via connections such as connecting lines 335 1, 3352 for adjusting the determined current value. The actuating devices 330 1, 3302 can be arranged, for example, in each case between a cell terminal (not shown in FIG. 1 ) and one of the connections 120 in 1, 1202 and / or comprise a switching device or a consumer device, which can be designed, for example, as a resistor such as a line resistor or controllable semiconductor component such as a line transistor. The consumer device can be connected in 1, 1202 between the cell terminal and the connection 120, for example, or can be connected to ground as a current sink.The operation of the device 310 is described in detail below with reference to FIG. 2.FIG. 2 shows a schematic view of a method 40 for cooling battery cells 100 1, 1002 according to another embodiment of the invention.The method, which may be executed in the device 310 and / or as a computer-implemented method, for example, begins with step 410. In step 410, for example, instructions stored in the memory device 314 are transferred to the processing device 312.In step 420, a measured value such as a temperature measured value or measured values such as a voltage measured value and a current measured value of a battery cell 100 1, 1002 or of the battery cells 100 1, 1002 are detected and transmitted to the processing device 312. The transmitted measurement value or values are received by the processing device 312. The processing device 312 can pre-process the transmitted measurement value or the transmitted measurement values, for example.In step 430, the processing device 312 determines a temperature value of the battery cell 100 1, 1002. from the transmitted, received or preprocessed measured value or the transmitted, received or preprocessed measured values.In step 440, the processor 312 compares the determined temperature value to a predetermined temperature threshold for the battery cell 100 1, 1002. The predetermined temperature threshold value may have been determined, for example, from data by simulation or from research, development, preseries or series. This threshold value can be updated, for example, when a workshop or electricity charging station is visited.If the determined temperature value does not exceed the predetermined temperature threshold 440.2, the method 40 branches to step 470 and then continues there.If the determined temperature value exceeds the predetermined temperature threshold 440.1, the method continues at step 450.In step 450, the processing device 312 may interrupt the current current I 1, I 2 through the battery cell 100 1, 1002. The processing device 312 may, for example, further or alternatively select the battery cell 100 1, 1002 or the other battery cell 100 2, 1001 from a plurality of battery cells 100 1, 1002. The selection may take into account, for example, the states of charge of the battery cells 100 in 1, 1002 fashion.In step 460, the processing device 312 sets a specific current value for the battery cell 100 1, 1002 or another battery cell 100 2, 1001, which is arranged adjacent to the battery cell 100 1, 1002 or the selected battery cell 100 1, 1002 such that the current I 1, I 2 through this battery cell 100 1, 1002 at the level of the specific current value causes a reduction in the temperature of the battery cell 100 1, 1002 or of the other battery cell 100 2, 1001, and therefore also causes 1, 1002, in the battery cell 100 because of the thermal connection. For this purpose, the processing device 312 can reduce the current I 1, I 2 to the determined current value. For this purpose, the processing device 312 can apply the determined current value to the current I 1, I 2. In this case, the set current value can cause charging of the battery cell 100 1, 1002 or of the other battery cell 100 2, 1001. Alternatively, the set current value may cause discharge of the battery cell 100 1, 1002 or the other battery cell 100 2, 1001. The processor 312 may set the current value as a clocked current value, or a continuous current value, or a pulse width modulated current value.The processor 312 may adjust the current value according to a current factor of the battery cell 100 1, 1002 or the other battery cell 100 2, 1001. At a current factor (C-rate) of 1 C, a battery cell is charged or discharged within one hour (60 minutes), i.e. for example, a battery cell having a capacity of 1 Ah flows for one hour a current of 1 A. At 0.1 C, the battery cell is charged or discharged within ten hours (600 minutes), i.e. at the capacity of 1 Ah, a current of 0.1 A flows for ten hours.At 0.2 C, the battery cell is charged or discharged within five hours (300 minutes), i.e. a current of 0.2 A flows for five hours at the capacity of 1 Ah.At 0.5 C, the battery cell is charged or discharged within two hours (120 minutes), i.e. a current of 0.5 A flows for two hours at the capacity of 1 Ah.At 2C, the battery cell is charged or discharged within 0.5 hours (30 minutes), i.e. a current of 2 A flows at the capacity of 1 Ah for 0.5 hours.The method ends with step 470.FIG. 3 shows exemplary temperature profiles 512... 536 of a battery cell 100 1, 1002 as a function of a charge quantity Q taken from the battery cell 100 1, 1002 at an ambient temperature of 20° C.For a current factor of 0.2 C, the temperature curves 512,... result. 516. 516. In this case, the temperature profile 512 is based on measurements on a real small cell in a radial design with a rated capacity of 7.5 Ah, while the temperature profile 516 is based on a thermal modeling of lithium ion batteries taking into account the entropic heat generation or the entropic heat consumption. The almost congruent temperature profiles 512, 516 result in a very good agreement of the modeling with the measurement. For comparison, temperature curve 514 shows a thermal modeling without taking into account the entropic heat generation (entropic heat generation) or the entropic heat consumption, which differs considerably from the measurement.For a current factor of 1C, the temperature curves 522,... result. 526. In this case, the temperature profile 522 is in turn based on measurements on the real small cell, while the temperature profile 526 is based on the corresponding thermal modeling taking into account the entropic heat generation or the entropic heat consumption. The largely congruent temperature profiles 522, 526 result in a good agreement of the modeling with the measurement. For comparison, temperature curve 524 shows a thermal modeling without taking into account the entropic heat generation or the entropic heat consumption, which is very significantly different from the measurement.For a current factor of 2C, the temperature curves 532,... are obtained. 536. In this case, the temperature profile 532 is again based on measurements on the real small cell, while the temperature profile 536 is based on the corresponding thermal modeling taking into account the entropic heat generation or the entropic heat consumption. The almost congruent temperature profiles 522, 526 in turn result in a very good agreement of the modeling with the measurement. For comparison, temperature curve 534 shows a thermal modeling without taking into account the entropic heat generation or the entropic heat consumption, which again differs quite considerably from the measurement.The entropic heat consumption that may occur instead of entropic heat generation counteracts overpotential heat generation (overpotential heat generation) and may lower the temperature of the battery cell due to the endothermic reaction. This effect is significantly greater for the current factor 0.2C than for the current factors 1C and 2C.Finally, it is noted that terms such as "comprising" and "having" or the like do not exclude that further elements or steps may be provided. The numbers used are merely exemplary, such that a plurality may include two, four, five, six, or more elements or steps. It is further noted that articles such as "a" or "an" do not exclude a plurality. It is further noted that ordinal numbers such as "first", "second", etc. are used only for distinguishing elements and steps without limiting an order of arrangement of the elements or execution of the steps. In addition, the features described in connection with the various embodiments can be combined with one another as desired. Finally, it is noted that the reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

Device (310) for cooling a battery cell (100 1, 1002) comprising: - a device (312) for receiving (420) measured values of the battery cell (100 1, 1002); - a device (312) for determining (430) a temperature value of the battery cell (100 1, 1002) from the received measured values; - a device (312) for comparing (440) the determined temperature value with a predetermined temperature threshold value for the battery cell (100 1, 1002); and - a device (312) for setting (460), if the determined temperature value exceeds the predetermined temperature threshold value, a determined current value for the battery cell (100 1, 100_ner 10_) or another battery cell (100 2, 1001), which is arranged adjacent to the battery cell (100 1, 1002) such that a current (I 1, I 2) through the battery cell (100 1, 1002) at the level of the determined current value causes a lowering of the temperature of the battery cell (100 1, 1002) or the other battery cell (100 2, 1001) further comprising - a device (312) for selecting, before the setting (460) of the determined current value, the battery cell (100 1, 100_ner24_) or the other battery cell (100 2, 1001) of a plurality of battery cells (100 1, 1002).The apparatus (310) according to claim 1, further comprising: - means (312) for preprocessing or filtering the received measurement values or - means (312) for interrupting (450) prior to the setting (460) of the determined current value, the current (I 1, I 2) through the battery cell (100 1, 1002).The device (310) according to claim 1 or 2, wherein: - the received measurement values comprise temperature measurement values; - the received measurement values comprise voltage measurement values and current measurement values; - the setting (460) of the determined current value comprises a reduction of the current (I 1, I 2) to the determined current value; - the setting (460) of the determined current value comprises an imposing of the determined current value on the current (I 1, I 2) ; - the set current value causes a charging of the battery cell (100 1, 1002) or the other battery cell (100 2, 1001) ; the set current value causes the battery cell (100 1, 1002) or the other battery cell (100 2, 1001) to discharge; or the set current value is a clocked current value or a continuous current value or a pulse width modulated current value.A battery module (200) comprising: - the device (310) according to any one of claims 1 to 3.A battery comprising: - the device (310) of any one of claims 1 to 3, or - the battery module (200) of claim 4.A battery system (10) comprising: - the device (310) according to any one of claims 1 to 3, - the battery module (200) according to claim 4, or - the battery according to claim 5.A vehicle comprising: - the device (310) according to any one of claims 1 to 3 connected to the vehicle, - the battery module (200) according to claim 4 connected to the vehicle, - the battery according to claim 5 connected to the vehicle, or - the battery system (10) according to claim 6 connected to the vehicle.A method (40) for cooling a battery cell (100 1, 1002) comprising: - receiving (420) measurement values of the battery cell (100 1, 1002); - determining (430) a temperature value of the battery cell (100 1, 1002) from the received measurement values; - comparing (440) the determined temperature value with a predetermined temperature threshold value for the battery cell (100 1, 1002); and - if the determined temperature value exceeds the predetermined temperature threshold value, setting (460) a determined current value for the battery cell (100 1, 1002) or another battery cell (100 2, 1001), which is arranged adjacent to the battery cell (100 1, 1002) such that a current (I 1, I 2) through the battery cell (100 1, 1002) at the level of the determined current value causes a lowering of the temperature of the battery cell (100 1, 1002) or of the other battery cell (100 2, 1001) further comprising - before the setting (460) of the determined current value, selecting the battery cell (100 1, 1002) or of the other battery cell (100 2, 100_ner70_) of a plurality of battery cells (100 1, 1002).The method (40) according to claim 8, further comprising: - preprocessing or filtering the received measurement values or - prior to setting (460) the determined current value, interrupting (450) the current (I 1, I 2) through the battery cell (100 1, 1002).The method (40) according to claim 8 or 9, wherein: - the received measurement values comprise temperature measurement values; - the received measurement values comprise voltage measurement values and current measurement values; - the setting (460) of the determined current value comprises reducing the current (I 1, I 2) to the determined current value; - the setting (460) of the determined current value comprises imposing the determined current value on the current (I 1, I 2) ; - the set current value causes charging of the battery cell (100 1, 1002) or the other battery cell (100 2, 1001) ; the set current value causes the battery cell (100 1, 1002) or the other battery cell (100 2, 1001) to discharge; or the set current value is a clocked current value or a constant current value or a pulse-width modulated current value.

Images