DE102013015700A1 - Method for producing a battery cell and battery cell - Google Patents

Abstract

The invention relates to a method for producing a battery cell (10) comprising the steps of: determining a design of the battery cell (10); Determining at least one point (28) within a housing (12) of the battery cell (10), on which depending on the design a detectable by at least one sensor size in an operation of the battery cell (10) has a higher value than at other locations within the housing (12) of the battery cell (10); and arranging the at least one sensor at the at least one location (28). Furthermore, the invention relates to a battery cell (10).

Description

The invention relates to a method for producing a battery cell and a battery cell, which has a housing in which an electrode arrangement is accommodated.

Battery cells, in particular lithium-ion cells as used for batteries of electric vehicles, hybrid vehicles and fuel cell vehicles, have a housing in which an electrode arrangement is arranged. In this case, the electrode arrangement comprises a sequence of anode material and cathode material, which are separated from one another by a separator made of an electrically non-conductive material. The active anode material and the cathode active material are applied to a respective drain material. As the lead material for the anode of a lithium-ion cell usually a copper foil is used and for the cathode aluminum foil. Furthermore, the electrode arrangement comprises an electrolyte which, in the case of the lithium-ion cell, ensures the transport of the lithium ions between the anode and the cathode during charging or discharging of the battery cell. In particular, in a cylindrical housing, the electrode arrangement is usually present as a so-called winding, in which said layer sequence is arranged rolled up on the housing. In prismatic housings, the electrode arrangement can also be present as a folded stack.

Usually, the monitoring of the battery cell takes place via externally detectable variables, which are mostly electrical variables or variables converted into electrical signals. In addition, there are types of battery cells which have a so-called "Current Interruption Device" which, in the event of an external short-circuit, acts as a fuse and interrupts the flow of current in the battery cell. However, such a device is comparatively sluggish.

On the basis of the detection of said variables from the outside, however, accurate statements about the real states inside the battery cell are not possible. At most there are models which allow to draw conclusions about the state of the battery cell by measuring electrical parameters. However, such models can only approximate the actual state of the battery cell. The state of the battery cell may include, in particular, the state of charge (SOC), or the state of health (SOH), which allows a statement about the aging of the battery cell, or the temperature, the internal pressure and the interior of the housing Battery cell present forces.

The disadvantage here is that the statements about the state of the battery cell, which can be made on the basis of external measurements, are insufficient. In addition, an early detection of events in the battery cell is not or only with difficulty possible, so that timely taking countermeasures is difficult.

More accurate knowledge about the state of the battery cell can be obtained via arranged within the housing of the battery cell sensors. That's how it describes DE 10 2008 052 986 A1 Lithium-ion battery cells of a battery, in which sensors are arranged within the battery cells. In this case, different sensors can detect different operating parameters or properties of the battery cell. The signals detected by the sensors of the battery cells are transmitted via an interface device coupled to all battery cells to a central control device which registers, stores and makes available the signals for later evaluation.

Furthermore, the describes DE 10 2008 063 136 A1 A lithium-ion battery for a vehicle with built-in temperature sensor, pressure sensor and electrical voltage sensor. If an increase in pressure or a temperature increase beyond a certain limit is detected via this sensor, the battery is disconnected from the on-board network of the vehicle.

The DE 10 2011 013 182 A1 describes a traction battery for electric vehicles, in which a temperature sensor is integrated in a battery cell.

A battery system with a plurality of lithium-ion battery cells is further in the DE 10 2010 038 860 A1 described. To monitor this battery system, a warning system is provided, which includes temperature sensors, pressure sensors, gas sensors and sensors for detecting mechanical and electrical voltages. If, in at least one battery cell of the battery system, a temperature increase which is accelerated in comparison with other battery cells is detected, which can be determined, for example, in degrees Celsius per minute, then warning signals are triggered. A critical condition may be further determined when the voltage decrease rate of a battery cell deviates from a predetermined reference value.

Object of the present invention is to provide a method for producing a battery cell and a battery cell, which or which allows an improved statement about the state of the battery cell.

This object is achieved by a method having the features of patent claim 1 and by a battery cell having the features of patent claim 9. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

The method according to the invention for producing a battery cell comprises a plurality of steps. In a first step, a design of the battery cell is determined. In this case, it is taken into account, for example, whether the battery cell to be produced should be cylindrical or prismatic or a bag cell (coffee bag cell). Furthermore, at least one point within a housing of the battery cell is determined on which, depending on the design, a variable detectable by means of at least one sensor has a higher value during operation of the battery cell than at other locations within the housing of the battery cell. In other words, depending on the design or the type of battery cell, a location which is particularly suitable for the function of the sensor within the housing of the battery cell is determined. Namely, at this point or at this location, a particularly immediate response of the sensor is to be expected when the size reaches the higher value. Finally, the at least one sensor is arranged at the at least one location.

This is based on the knowledge that the appropriate placement of the sensors within the housing of the battery cell makes it possible to detect changes in the state of the battery cell particularly quickly and accurately. This makes it possible to make very reliable statements about cell-internal processes. This makes it possible, on the one hand, to detect an aging of the battery cells in a particularly realistic manner. On the other hand negative effects can be detected particularly quickly for the battery cell, which can lead to damage to the battery cell. If such negative effects are caused by external influences, in particular by a load on the battery cell, then these external influences can then be reduced in time so that there is no damage to the battery cell or that no safety risk arises.

In an advantageous embodiment of the invention, at least one temperature sensor is arranged at the at least one location as the at least one sensor. This is based on the knowledge that it is not indifferent from a thermal point of view at which points inside the housing of the battery cell temperature sensors are arranged. For example, in the case of a battery cell in which the electrode arrangement is in the form of a winding, the hottest point at the start of the winding can be present during operation, ie in the center of the coil.

However, depending on the design of the battery cell, particularly hot spots, ie so-called hot spots, may occur at other locations of the electrode arrangement during operation. Such hot spots may eventually lead to local overheating and then cause an internal short circuit at these exact locations. As a result of an internal short circuit, it can then lead to a fire of the battery cell, which is also referred to as thermal runaway.

In the present case, preference is now given to attaching a plurality of temperature sensors to exactly those points where, depending on the design of the battery cell, the hottest points are present during operation. This makes it possible to react to a change in the temperature of the battery cell at a particularly early stage. It can then be separated, for example, the battery cell or a battery having a plurality of battery cells, via corresponding switching devices from a power grid, for which the battery provides power or through which it is charged. By such a load shedding, in which the current flow in the battery cell approaches zero, there is a cooling in the battery cell, so that in particular a fire of the same can be avoided.

If a battery having the battery cells is a battery for a vehicle, then the battery can be disconnected from the electrical system, for example via appropriate contactors, in order to prevent further current flow from the battery or into the battery. This returns the battery to a thermally stable state.

By integrating temperature sensors at hot spots within the housing of the battery cells, an overuse and aging of the battery cell as well as a heat input into the same can be detected over a temperature image as a function of time. This allows insightful conclusions, such as the life of the battery cell.

As further advantageous, it has been shown that the at least one temperature sensor is arranged on at least one arrester element of an electrode arrangement of the battery cell. In the case of lithium-ion cells, films are preferably used as arrester elements, namely a copper foil for the anode and an aluminum foil for the cathode. If now the at least one temperature sensor is arranged directly on this arrester foil during the manufacturing process of the electrode arrangement, it can be ensured particularly well that the heat produced during operation is measured exactly where, depending on the design of the battery cell during operation, a particularly large heat development is to be expected ,

In addition, arranging the sensor on the arrester element ensures that the resulting heat can be measured very quickly and not offset in time. This is due to the thermal conductivity of the arrester element. Thus, it does not need the heat as in any other place in the interior of the housing of the battery cell arranged temperature sensor still bridging any air gaps in order to be detected by the temperature sensor can. Rather, by means of the temperature sensor arranged directly on the arrester element, a rise in temperature is recorded particularly early in time, so that the time available for taking countermeasures is increased.

Since the electrode assembly is usually constructed as a winding, stacking or folding during manufacture, the temperature sensors can be attached to the hot spots dependent on the cell type or the design directly when winding or stacking or folding the film serving as the arrester element. This brings a particularly simple and to the targeted arrangement of the sensors in the relevant places with it.

It is furthermore advantageous if at least one force sensor is arranged at the at least one location as the at least one sensor. Thus, the arrangement of force sensors preferably takes place at strategically important locations within the housing of the battery cell. By means of force sensors arranged at these points, a change in the state of the battery cell can be detected in a particularly simple and reliable manner.

The at least one force sensor can in this case be arranged on at least one arrester element of an electrode arrangement of the battery cell. Additionally or alternatively, it can be provided that the force sensor is arranged on a wall of the housing of the battery cell. Thus, changes, in particular an expansion of the electrode arrangement and contraction of the same, or a corresponding deformation of walls of the housing of the battery cell can be detected in a particularly simple and secure manner. These measurements make it possible to draw conclusions about the stress and aging of the battery cell, and it is possible to detect impermissible deviations.

Furthermore, as the at least one sensor, at least one pressure sensor and / or a density sensor and / or a gas sensor and / or a sensor for detecting a concentration of an electrolyte in the housing of the battery cell can be arranged at the at least one location. By detecting variables that can be detected with the mentioned sensors, the state of the battery cell can be deduced particularly well. The pressure in the housing of the battery cell is distributed relatively quickly and evenly. Nevertheless, it is also advantageous in the integration of the pressure sensor into the interior of the battery cell when it is arranged so that pressure increases based on a chemical reaction can be detected particularly quickly.

In the production of the battery cell, an evaluation device is furthermore preferably arranged within the housing of the battery cell, which is connected to the at least one sensor via at least one communication link. As an evaluation device, a corresponding microchip, such as an application-specific integrated circuit (ASIC) can be used, which allows the evaluation of the data of multiple sensors. During evaluation, in particular a first derivative and / or a second derivative of the detectable variables after the time can be used to obtain a reliable statement about the state of the battery cell. Due to the fact that the evaluation device is already integrated in the production of the battery cell in this together with the sensors, eliminates the otherwise required effort for a subsequent connection of the sensors with the evaluation. This makes the evaluation of the measured variables detected by the sensors particularly simple.

Finally, it has proven to be advantageous if the evaluation device is provided with at least one interface, by means of which a signal can be transmitted to a device arranged outside the battery cell. For this purpose, the interface can be provided for connecting separate lines, via which the communication with the device takes place outside the battery cell. Additionally or alternatively, the signal can also be communicated to the outside via the already existing battery poles or terminals of the battery cell, for example via a modulation. Furthermore, the interface can be designed to transmit a radio signal. This is advantageous in terms of a hermetically sealed closure of the battery cell. However, the interface can also be designed in addition or alternatively to transmit the signal by optical means, such as by an optical waveguide or the like is provided.

By transmitting a signal indicating the state to the device arranged outside the battery cell, which may in particular be a higher-level control system such as a battery management system, it is possible to respond very quickly to a critical change in the state of the battery cell.

The battery cell according to the invention comprises a housing in which an electrode arrangement is accommodated. In addition, at least one sensor is arranged in the housing, which sensor serves to detect a quantity dependent on the state of the battery cell. Here, the at least one sensor is arranged at least at one point within the housing of the battery cell to which depending on a design of the battery cell dependent on the state of the battery cell size in an operation of the battery cell has a higher value than at other locations within the housing battery cell. By arranging the at least one sensor at locations which are particularly suitable for detecting the quantity indicating the state of the battery cell, it is possible to obtain improved statements about the state of the battery cell.

The advantages and preferred embodiments described for the method according to the invention also apply to the battery cell according to the invention and vice versa.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention. Thus, embodiments are also included and disclosed by the invention, which are not explicitly shown or explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawings. Showing:

1 in a partially sectioned view of a battery cell having a housing in which an electrode assembly is disposed, wherein within the housing further schematically shown sensors and a microchip are arranged;

2 schematically the communication connection between the sensors and the microchip and an interface of the microchip for communication with a battery management system; and

3 schematically the battery cell according to 1 in a further sectional view.

1 shows a battery cell 10 , which is designed as a prismatic lithium-ion cell. A plurality of such battery cells 10 is usually combined to form a battery module, as used in a vehicle battery of an electric vehicle or hybrid vehicle. The - in this case prismatic - battery cell 10 provides a certain rated voltage. When using the battery cell 10 for the vehicle battery, therefore, a plurality of such battery cells 10 electrically interconnected to generate a correspondingly high voltage and correspondingly high currents.

A housing 12 the battery cell 10 is shown cut. Accordingly, one is in the housing 12 the battery cell 10 arranged electrode arrangement 14 to see which is formed as a stack or winding an anode, a cathode and the cathode separating from the anode separators. The electrochemically active material of the cathode and the anode is in this case applied to a respective arrester element, with aluminum preferably being used as the arrester film for the cathode 46 is used (cf. 3 ) and for the anode copper.

The same-named arrester elements of the cathode are in a contact area 16 connected to each other, which in the present case via a line 18 with a first electrical pole 20 the battery cell 10 connected is. In an analogous manner, the arrester elements are to the electrode assembly 14 belonging anode in one (in 1 unrecognizable) contact area connected to each other and another line 22 with another pole 24 the battery cell 10 electrically coupled.

To statements about the condition of the battery cell 10 to be able to meet, are present within the housing 12 a plurality of sensors arranged. For example, temperature sensors allow 26 the detection of the temperature inside the battery cell 10 , Here are the temperature sensors 26 in places 28 inside the case 12 arranged at which during operation of the battery cell 10 elevated temperatures occur. The location of such hot spots or hot spots 28 However, it depends on the cell type, ie on the design of the battery cell 10 ,

For example, these digits are located 28 in the presently shown by way of example prismatic battery cell in other places than in a cylindrical battery cell or a so-called Coffeebag cell (bag cell). Already in the production of the battery cell 10 Therefore, in the present case, the design thereof is taken into account in that the temperature sensors 26 at the depending on the design hot spots or bodies 28 to be ordered. The location of the hot spots during operation of the battery cell 10 can be detected by taking pictures with thermal imaging cameras or the like.

The temperature sensors 26 are then in the manufacture of the electrode assembly 14 directly on the arrester foils 46 applied, so for example on the copper foil and on the aluminum foil in the lithium-ion cell. Thus, for example, in an electrode arrangement designed as a winding 14 be sure that one of the temperature sensors 26 located in the center of the roll. However, at the prismatic battery cell 10 also more jobs 28 exposed as typical hot spots, and consequently are also in these places 28 present temperature sensors 26 arranged.

Also force sensors 30 are inside the case 12 at corresponding locations of the electrode assembly 14 arranged in which in operation of the battery cell 10 due to a stress of the same increased tensile forces occur. Again, the force sensors 30 preferably on components of the electrode arrangement 14 arranged, this arrangement already in the manufacture of the battery cell 10 depending on the design of the same.

As additional sensors within the housing 12 the battery cell 10 are present a pressure sensor 32 , a gas sensor 34 and a density sensor 36 shown. All of these sensors are already in the production of the battery cell 10 at particularly suitable locations within the housing for the acquisition of the respective measurand 12 placed.

The sensors are over in 2 schematically shown communication links 38 with an evaluation device in the form of a microchip 40 connected, which also within the housing 12 the battery cell 10 is arranged.

In the evaluation of the measured variables detected by the sensors by means of the microchip 40 For example, a very reliable statement about the cell-internal processes can be made about the first or second derivation of variables recorded with the sensors after the time. This allows the aging of the battery cell 10 to determine and also to recognize negative effects such as a temperature increase or a pressure build-up in time.

If such an event is detected, then the microchip 40 via an interface 42 corresponding signals to an outside of the battery cell 10 arranged, higher-level control system. This control system may be a battery management system 44 act. By means of such a battery management system 44 can be, for example, when the battery cell overheats 10 (not shown here) contactors open and so the battery cells 10 disconnect the battery from a vehicle electrical system. the interface 42 , which allows the transmission of the signals to the outside, can be realized by providing separate lines or cables. However, it can also signal transmission by modulating over the poles 20 . 24 the battery cell 10 done, or the interface 42 can be designed to transmit a radio signal. Furthermore, optical transmission via an optical fiber or the like is possible.

In the sectional view in 3 is one of the arrester foils 46 the electrode assembly 14 shown schematically and also the arrangement of the temperature sensors 26 and the force sensors 30 on this arrester foil 46 , Furthermore are by directional arrows 48 Forces illustrated. In through the directional arrows 48 indicated directions, the electrode assembly stretch 14 and walls of the housing 12 the battery cell 10 off when the battery cell 10 electrical power dissipates or absorbs. Furthermore, it is off 3 can be seen that the other sensors, such as the pressure sensor 32 , the gas sensor 34 and the density sensor 36 on a component of the electrode assembly 14 , especially on the arrester foil 46 can be arranged.

Through the integration of the microchip 40 and the sensors in the battery cell 10 already during the manufacturing process of the battery cell 10 and on strategically important and depending on the design of the battery cell 10 determined points can be a stress and aging of the battery cell 10 capture well and safely. This allows improved statements about the state of the battery cell 10 to meet.

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 102008052986 A1 [0006]
• DE 102008063136 A1 [0007]
• DE 102011013182 A1 [0008]
• DE 102010038860 A1 [0009]

Claims (9)

Method for producing a battery cell ( 10 ) comprising the steps of: - determining a design of the battery cell ( 10 ); - determining at least one position ( 28 ) within a housing ( 12 ) of the battery cell ( 10 ), at which, depending on the design, a variable detectable by means of at least one sensor in an operation of the battery cell ( 10 ) has a higher value than elsewhere in the housing ( 12 ) of the battery cell ( 10 ); and - arranging the at least one sensor at the at least one location ( 28 ). Method according to claim 1, characterized in that as the at least one sensor at least one temperature sensor ( 26 ) at least one place ( 28 ) is arranged. Method according to claim 2, characterized in that the at least one temperature sensor ( 26 ) on at least one arrester element ( 46 ) of an electrode arrangement ( 14 ) of the battery cell ( 10 ) is arranged. Method according to one of claims 1 to 3, characterized in that as the at least one sensor at least one force sensor ( 30 ) at least one place ( 28 ) is arranged. Method according to claim 4, characterized in that the at least one force sensor ( 30 ) on at least one arrester element ( 46 ) of an electrode arrangement ( 14 ) of the battery cell ( 10 ) and / or on a wall of the housing ( 12 ) of the battery cell ( 10 ) is arranged. Method according to one of claims 1 to 5, characterized in that as the at least one sensor at least one - pressure sensor ( 32 ) and / or density sensor ( 36 ) and / or - gas sensor ( 34 ) and / or sensor for detecting a concentration of an electrolyte in the housing ( 12 ) of the battery cell ( 10 ) at least one place ( 28 ) is arranged: Method according to one of claims 1 to 6, characterized in that inside the housing ( 12 ) of the battery cell ( 10 ) an evaluation device ( 40 ) is arranged, which with the at least one sensor via at least one communication path ( 38 ) is connected. Method according to claim 7, characterized in that the evaluation device ( 40 ) with at least one interface ( 42 ), by means of which a signal from outside the battery cell ( 10 ) ( 44 ) is transferable. Battery cell with a housing ( 12 ) in which an electrode arrangement ( 14 ), wherein in the housing ( 12 ) at least one sensor for detecting a condition of the battery cell ( 10 ) dependent size, characterized in that the at least one sensor at least one location ( 28 ) within the housing ( 12 ) of the battery cell ( 10 ) is arranged, at which, depending on a design of the battery cell ( 10 ) the condition of the battery cell ( 10 ) dependent size in an operation of the battery cell ( 10 ) has a higher value than elsewhere in the housing ( 12 ) of the battery cell ( 10 ).

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