DE102013201396A1 - Battery system i.e. lithium ion battery system connected with propulsion system of e.g. motor vehicle, has humidity sensor determining moisture content of atmosphere around battery within battery casing - Google Patents

Abstract

The battery system (60) has a battery casing (50) in which a battery (40) is arranged. A thermal element (30) is provided through which fluid e.g. glycol or water solution flows, and is adapted to hold the battery in predetermined temperature range. A humidity sensor (10) determines moisture content of the atmosphere around the battery within the battery casing. The humidity sensor is executed as surface-micromechanical sensor. A processor unit is connected with a communication bus system.

Description

The present invention relates to a battery having a battery housing and at least one battery cell arranged inside the battery housing, the battery having at least one humidity sensor which is designed to determine the moisture content of the atmosphere within the battery housing around the at least one battery cell.

State of the art

For hybrid and electric vehicles in particular lithium-ion battery systems are used as traction batteries because of their relatively high energy density and low self-discharge. During operation, these lithium-ion battery cells heat during charging and discharging due to their internal resistance and the power loss occurring as well as due to occurring within the battery cells electrochemical processes. The operating temperature range of lithium-ion batteries ranges from -40 ° C to + 60 ° C. From battery cell temperatures of 40 ° C, the calendar aging of battery cells and thus of the battery increases more and more. For this reason, the battery cells of a battery must be actively cooled and all kept at the same temperature as possible. Such cooling usually takes place via a cooling system containing a cooling liquid.

For example, in a cooling system of lithium-ion batteries for automotive applications, a glycol / water solution is used as the cooling liquid. This coolant has a temperature of about 20 ° C, so that forms in the battery, which is vented via a pressure equalization valve, not so much unwanted condensation. At low temperatures, the glycol / water solution is also used to heat the battery. As a result, the internal resistance of the battery cells is reduced, which increases their performance so that they can provide the cold start current required for starting the vehicle.

According to the current state of the art is not recognized when the cooling system of the lithium-ion batteries, for example, as a result of an accident, leaking, or if there is a leakage of glycol / water solution within the battery. Furthermore, it can not be recognized in the current state of the art whether condensation has been deposited in the battery, for example on the battery cells or on the cooling system in contact with the battery cell plates.

The fluid within the cooling system, here the glycol / water solution, is electrically conductive and can carry correspondingly high currents at high voltages, such as those in traction batteries of hybrid and electric vehicles. In addition, the fluid crystallizes after drying and forms electrically conductive bridges, so-called dendrites, which can lead to low-impedance side or short circuits between the battery poles or in each of the wetted by the fluid cell monitoring electronics. Such an external short circuit can therefore also occur after damage to the cooling system, for example after a crash. Furthermore, dendrites can also be formed between hardcase housings, that is to say the housings of the battery cells with insulation layers damaged by the crash.

Such short circuits can lead to a strong increase in temperature of the battery cells with subsequent fire. Therefore, some approaches are already known in the prior art, which are devoted to the attempt to counteract the problem described above.

For example, is from the DE 10 2010 062 178 A1 a method for monitoring the function of a Temperierungssystems for controlling the temperature of a lithium-ion battery system, wherein the Temperierungssystem comprises a cooling fluid. The functional state of the temperature control system is determined on the basis of a heat balance of the battery system and on the basis of measured temperatures for each of the modules of the battery system.

Furthermore, from the DE 10 2009 045 271 A1 a battery with a number of battery cells for electric cars and hybrid drives for vehicles known, wherein upon detection of a vehicle accident, an excess temperature or self-adjusting leakage of a liquid in which the batteries are stored, an emergency cooling process is triggered.

Disclosure of the invention

According to the invention, a battery is provided which comprises a battery housing and at least one battery cell, which is arranged in the battery housing. Furthermore, the battery comprises at least one thermal element, which can be traversed by a fluid and is designed to hold the at least one battery cell in a predefined temperature range. According to the invention, the battery has at least one humidity sensor, which is designed to determine the moisture content of the atmosphere within the battery housing, around the at least one battery cell.

The advantage of a battery with such a humidity sensor is that in selbiger a leakage of the Fluids from the thermal element can be detected immediately, so countermeasures, such as a discharge of the battery, can be initiated early. By such leakage detection, it is possible to convert the battery, for example, before the occurrence of short circuits in an electrochemically safe state. This increases the safety of the battery and represents an improvement over the batteries of the prior art.

In a preferred embodiment, the battery has a circuit which is designed to convert the battery from a first operating state into a second operating state as soon as the humidity content of the atmosphere determined by the humidity sensor exceeds a predetermined first threshold value. With such a first threshold is set for the humidity of the atmosphere in the immediate vicinity of the battery cell, a limit beyond which the battery can be transferred, for example, in an electrochemically safe state. This significantly increases the safety of the battery. The first operating state of the battery preferably corresponds to an active operating state of the battery.

Preferably, the battery has a circuit which is adapted to transfer the battery from a first operating state to a second operating state, as soon as the amount of increase in time of the moisture content of the atmosphere exceeds a predetermined second threshold. With such a second threshold, the amount of time increase or change in the humidity of the atmosphere in the immediate vicinity of the battery cell is set a limit above which, for example, the discharge of the battery can be brought about. This increases the safety of the battery again. By increasing the moisture content in time is meant increasing the moisture content of the atmosphere in the battery case in a predetermined period of time.

Preferably, the circuit is designed as a discharge circuit, which is designed to carry out a discharge of the battery when the predetermined first and / or second threshold value is exceeded, wherein the battery is discharged in the second operating state. In other words, the second operating state of the battery preferably corresponds to a state in which the battery is discharged. In the discharged state of the battery is a greatly reduced, if not even fire risk more. It is transformed into a thermally uncritical state. As a result, the safety of the battery after its discharge is greatly increased.

In a preferred embodiment, the battery further comprises a warning element, which is designed to indicate the exceeding of the first and / or the second predetermined threshold value. Further preferably, the warning element is designed as an optical element. Particularly preferably, the warning element is designed as a warning lamp. In such an embodiment, for example, the user of the battery, a leak of the thermal element and the transfer of the battery from the first to the second operating state can be displayed.

In a preferred embodiment, the humidity sensor is designed as a capacitive sensor. Capacitive sensors operate on the basis of changing the capacitance of a single capacitor or a whole capacitor system. Capacitive sensors are very accurate and relatively easy to produce.

Further preferably, the humidity sensor is designed as a surface micromechanical sensor. Particularly preferably, the moisture sensor is designed as a silicon surface micromechanical sensor. Micromechanical sensors are particularly small, inexpensive and energy-saving. Surface micromechanical silicon sensors are the advancement of bulk micromechanical sensors in silicon. They are particularly small and cheaper to produce.

In a preferred embodiment, the battery further comprises a processor unit, which is connected to the at least one humidity sensor and which comprises a storage element. Furthermore, the processor unit is preferably designed as a microcontroller. Furthermore, the memory element is preferably designed as a nonvolatile memory, for example as an EEPROM memory. This makes it possible, for example, to collect and evaluate information about leaks of the thermal element.

Preferably, the processor unit is designed to store the duration in which the first and / or the second predetermined threshold value is exceeded as a data record in the memory element. As a result, various evaluations of the state of the battery or the state of the thermal element installed inside the battery, for example a cooling element, become possible.

Preferably, the processor unit can be connected to a communication bus system, via which data records stored in the memory element can be read out. Further preferably, the communication bus system to which the processor unit is connectable, as a CAN bus system, FlexRay bus system or designed as a LIN bus system. If the processor unit of the battery cell according to the invention is connected to such a communication bus system, in such an exemplary embodiment the data records can be transmitted via the communication bus system, for example to external control units or arithmetic units, where they can then be further used or otherwise evaluated.

Particularly preferably, the battery is designed as a lithium-ion battery. Advantages of such batteries include their comparatively high energy density and their high thermal stability. Another advantage of lithium-ion batteries for hybrid or electric vehicles is that they are not subject to memory effect and have only a very low self-discharge current.

Furthermore, a motor vehicle is provided with a battery according to the invention, wherein the battery is connected to a drive system of the motor vehicle.

Advantageous developments of the invention are specified in the subclaims and described in the description.

drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below. Show it:

1 an embodiment of a battery according to the invention, which is connected to an exemplary cooling system, and

2 an exemplary, schematic electronic interconnection of the humidity sensors within an embodiment of a battery according to the invention.

Embodiments of the invention

In the 1 is an embodiment of a battery according to the invention 60 shown which an exemplary cooling system 31 connected. This cooling system 31 is not part of the battery according to the invention 60 and is listed here for your convenience only. A battery according to the invention 60 can also be connected to any other cooling system 31 which is fundamentally different from the one in 1 can distinguish shown. Also, batteries of the invention 60 be realized, which without a cooling system 31 work or not with a cooling system 31 are connectable.

The battery 60 includes a battery case 50 which is in 1 is indicated only schematically. Furthermore, the battery includes 60 in this embodiment purely by way of example a plurality of battery cells 40 which inside the battery case 50 are arranged and of which a single schematically in 1 is indicated. Furthermore, batteries according to the invention can also be used 60 be realized, which only a single battery cell 40 exhibit. The battery according to the invention 60 includes a thermal element in this embodiment 30 that of a fluid 2 can be flowed through and adapted to the plurality of battery cells 60 to keep in a predefined temperature range. In this embodiment, the thermal element 30 purely by way of example as a combination of cooling plates and cooling fins executed, which in this embodiment purely by way of example a fluid 2 leading pipes 21 with the cooling system 31 are connected. However, it is also possible to use other batteries according to the invention 60 be executed, in which the thermal element 30 differently, for example, as cooling channels, or designed quite differently.

In this embodiment, the battery includes 60 purely as an example four humidity sensors 10 , which are adapted to the moisture content of the atmosphere within the battery case 50 around the multitude of battery cells 40 around, to determine. In other words, the humidity sensors are 10 designed to reduce the moisture content of the atmosphere in close proximity to the battery cells 40 , So the moisture content of the battery cells 40 directly surrounding atmosphere to determine or monitor. In this embodiment, two of the humidity sensors 10 for determining the moisture content purely by way of example directly on the thermal element 30 arranged while the remaining two humidity sensors 10 purely by way of example next to the thermal element 30 , in close proximity to the pipes 21 are arranged, over which the thermal element 30 with the cooling system 31 connected is. However, it is also possible batteries according to the invention 60 with only one, two, three or more than four humidity sensors 10 be executed, in which the humidity sensors 10 also elsewhere in the battery 60 can be arranged.

In the embodiment of 1 are the humidity sensors 10 purely by way of example as capacitive surface micromechanical silicon sensors. However, it is also possible batteries according to the invention 60 be executed, in which the humidity sensors 10 Although they are designed as capacitive, micromechanical sensors, but not as a surface-micromechanical silicon sensors or as a micromechanical Humidity sensors, which are not silicon sensors. Furthermore, batteries according to the invention can also be used 60 be implemented, in which the humidity sensors are not designed as micromechanical sensors or not as capacitive sensors, but are designed as other sensors.

This in 1 illustrated, purely exemplary cooling system 31 includes in this embodiment a compressor 28 , a capacitor 27 as well as an evaporator 26 , which have a variety of pipes 21 through which a fluid 2 to be able to flow, are interconnected. Furthermore, the cooling system includes 31 a variety of shut-off valves 25 of which two in 1 are shown. In this embodiment, the cooling system 31 , as already mentioned, about pipes 21 with the thermal element 30 the battery 60 connected. All elements together form a closed circuit, which the battery cells 40 the battery 60 to cool or to heat. About an arrow 18 is in 1 shown as the thermal element 30 the battery 60 through the evaporator 26 from the fluid 2 produced gas is cooled.

The 2 shows an exemplary, schematic electronic interconnection of the humidity sensors 10 within an embodiment of a battery according to the invention 60 , In other words, that shows 2 schematically an exemplary, electronic connection of the humidity sensors 10 within an embodiment of a battery according to the invention 60 ,

In the embodiment of the battery according to the invention 60 this is purely an example of the in 1 shown. However, with the exception of the humidity sensors 10 in 1 none of the 2 shown electronic components shown. In this embodiment, the battery 60 a circuit 20 which is adapted to the battery 60 from a first active operating state to a second operating state, as soon as passing through the humidity sensor 10 certain moisture content of the atmosphere exceeds a predetermined first threshold. In other words, the battery points 60 in this embodiment, a circuit 20 which is adapted to the battery 60 from a first operating state to a second operating state, as soon as the moisture content in the battery cells 40 the battery 60 surrounding atmosphere exceeds a predetermined limit, the predetermined first threshold. Furthermore, the same circuit can 20 in this embodiment, the battery 60 from a first active operating state in the above-described, to transfer or set second operating state, as soon as the amount of increase in time of the moisture content of the atmosphere around the battery cells 40 around exceeds a predetermined second threshold. In other words, the circuit is capable 20 the battery 60 in this embodiment, the battery 60 from a first active operating state to a second operating state as soon as the battery cells 40 surrounding atmosphere detects a change in the moisture content per predetermined period of time whose amount is above a predetermined limit, the predetermined second threshold. In this case, the predetermined time period can also be chosen infinitesimally small.

Such an increase in the moisture content of the atmosphere around the battery cells 40 around can occur, for example, when the thermal element 30 or the pipes 21 over which the thermal element 30 with the cooling system 31 connected, have a leak. In this embodiment, the circuit 20 purely by way of example designed as a discharge circuit, which is designed to discharge the predetermined first or second predetermined threshold, a discharge of the battery 60 carry out the battery 60 discharged in the second operating state. In other words, the discharge circuit discharges the battery cells 40 if and only if either the first or the second above described, predetermined threshold is reached. In this embodiment, the battery includes 60 Furthermore, a warning element 5 which is adapted to indicate the exceeding of the first or the second predetermined threshold value. In this embodiment, the warning element is 5 purely by way of example a warning lamp, which for the user of the battery 60 is visible and lights up as soon as the first or the second, described above, predetermined threshold is exceeded. However, batteries according to the invention can also be used 60 with differently executed warning elements 5 be realized, for example, generate an audible sound or otherwise be perceived.

In this embodiment, the battery 60 furthermore a processor unit 4 on, which in this embodiment with the four humidity sensors 10 is connected and which is a memory element 6 includes. In this embodiment, the processor unit is 4 purely by way of example as a microcontroller, which also has, purely by way of example, an analog-to-digital converter unit. The storage element 6 is executed purely by way of example as non-volatile memory in this embodiment. This non-volatile memory is also designed in this embodiment, purely by way of example as EEPROM memory.

The processor unit 4 of in 2 illustrated embodiment of a battery according to the invention 60 In this embodiment, it is designed to monitor the exceeding of the first and the second, predetermined threshold value and, if the first or the second threshold value is exceeded, a discharge by the circuit 20 , ie the discharge circuit, to initiate or cause. In other words, the processor unit is 4 formed in this embodiment, the moisture content and the amount of increase in time of the moisture content of the battery cells 40 surrounding atmosphere by means of humidity sensors 10 to monitor. Furthermore, the processor unit 4 In this embodiment, purely by way of example, the duration in which the first or the second predetermined threshold value is exceeded is formed as a data record in the memory element 6 , so in the EEPROM memory to save. In other words, the processor unit is 4 in this exemplary embodiment, the duration in which the first and / or second predetermined threshold values are exceeded is determined and stored. In this embodiment, the processor unit 4 purely by way of example a communication interface 3 on which the processor unit 4 with a communication bus system 1 is connectable. Is the processor unit 4 with such a communication bus system 1 are then connected in the memory element 6 , So in this embodiment, the EEPROM memory, stored records on this communication bus system 1 read. In other words, the records that are stored in the memory element 6 from the processor unit 4 stored with the communication bus system connected 1 via the communication interface 3 and via the communication bus system 1 For example, be transmitted to an external controller or to an external evaluation. The communication bus system 1 is not part of the battery according to the invention 60 , In this embodiment, the communication bus system 1 purely by way of example as a CAN bus system. However, it is also possible batteries according to the invention 60 with processor units 4 which are a communication interface 3 for connecting to other communication systems 1 or the connection to other communication bus systems 1 exhibit.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010062178 A1 [0007]
• DE 102009045271 A1 [0008]

Claims (11)

Battery ( 60 ), comprising - a battery case ( 50 ), - at least one battery cell ( 40 ), which in the battery case ( 50 ), - at least one thermal element ( 30 ), which depends on a fluid ( 2 ) and is adapted to the at least one battery cell ( 40 ) in a predefined temperature range, characterized in that the battery ( 60 ) at least one humidity sensor ( 10 ), which is adapted to the moisture content of the atmosphere within the battery housing ( 50 ) around the at least one battery cell ( 40 ) around. Battery ( 60 ) according to claim 1, wherein the battery ( 60 ) a circuit ( 20 ), which is adapted to the battery ( 60 ) from a first operating state to a second operating state, as soon as passing through the humidity sensor ( 10 ) certain moisture content of the atmosphere exceeds a predetermined first threshold. Battery ( 60 ) according to one of the preceding claims, wherein the battery ( 60 ) a circuit ( 20 ), which is adapted to the battery ( 60 ) to transfer from a first operating state to a second operating state, as soon as the amount of increase in time of the moisture content of the atmosphere exceeds a predetermined second threshold. Battery ( 60 ) according to claim 2 or 3, wherein the circuit ( 20 ) is designed as a discharge circuit, which is designed, upon exceeding the predetermined first and / or the second threshold value, a discharge of the battery ( 60 ), the battery ( 60 ) is discharged in the second operating state. Battery ( 60 ) according to one of claims 2 to 4, wherein the battery ( 60 ) a warning element ( 5 ), which is designed to indicate the exceeding of the first and / or the second predetermined threshold value. Battery ( 60 ) according to one of the preceding claims, wherein the humidity sensor ( 10 ) is designed as a capacitive sensor. Battery ( 60 ) according to one of the preceding claims, wherein the humidity sensor ( 10 ) is designed as a surface micromechanical sensor. Battery ( 60 ) according to one of the preceding claims, wherein the battery ( 60 ) a processor unit ( 4 ), which with the at least one humidity sensor ( 10 ) and which a memory element ( 6 ). Battery ( 60 ) according to claim 2 or 3 and claim 8, wherein the processor unit ( 4 ) is adapted to the duration in which the first and / or the second predetermined threshold value is exceeded, as a record in the memory element ( 6 ) store. Battery ( 60 ) according to claim 9, wherein the processor unit ( 4 ) with a communication bus system ( 1 ) is connectable, over which in the memory element ( 6 ) stored records are readable. Motor vehicle with a battery ( 60 ) according to one of claims 1 to 10, wherein the battery ( 60 ) is connected to a drive system of the motor vehicle.

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