EP3602673A1

EP3602673A1 - Diagnosis of batteries

Info

Publication number: EP3602673A1
Application number: EP18717252.3A
Authority: EP
Inventors: Alexander GITIS
Original assignee: Rheinisch Westlische Technische Hochschuke RWTH
Current assignee: Rheinisch Westlische Technische Hochschuke RWTH
Priority date: 2017-03-31
Filing date: 2018-03-27
Publication date: 2020-02-05
Also published as: CN110574215A; WO2018178050A1; US20210194070A1; DE102017205561A1

Abstract

The invention relates to a diagnostic device (10) for critical changes, particularly pressure changes, gas development and temperature changes, in batteries having multi-layered structures, to a battery system (50) having such a diagnostic device (10) and to a method (100) for diagnosing critical changes of such batteries by means of the diagnostic device. According to the invention, a diagnostic device (10) is provided for determining critical changes to physical properties relative to a target state in battery cells (12) having a structure comprising a plurality of layers (14), wherein the layers (14) are frictionally connected to each other, having at least one receiver (18) and, optionally, additionally, a transmitter (16) for arrangement on the housing (20) and/or cell contact (22) of the battery cell (12), wherein the receiver (18) is suitable for receiving acoustic plate waves (24) and/or acoustic torsion waves (26) and for transmitting a corresponding signal (28) to an evaluating unit (30), which is provided in order to evaluate one or more parameters (32), which are characteristic for an actual state of the battery cell (12), and for comparing them to at least one previously defined threshold (34), wherein exceeding or falling short of the threshold (34) is evaluated as identification of battery cells having a critical change to the physical properties thereof, wherein, in the case of the diagnostic device having a transmitter, the transmitter (16) is suitable for exciting the acoustic plate waves (24) and/or the acoustic torsion waves (26) in the battery cell (12) having a propagation direction along the layers (14).

Description

Diagnosis of batteries

Field of the invention

The invention relates to a diagnostic device of critical

Changes, in particular pressure changes, gas evolution and temperature changes, in batteries with multilayer structures, on a battery system with such a diagnostic device and a method for diagnosing critical change of such batteries with the

Diagnostic device.

Background of the invention

The use of electrical or electronic devices, in particular portable devices, is often dependent on electrochemical cells as a power supply, so-called "battery cells" or "batteries". Batteries can be used in electronic devices such as telecommunications equipment (eg, cell phones, tablets, computers), transportation (such as cars, airplanes, boats), but also in non-portable devices such as back-up batteries for central power supplies.

Due to external operating conditions of battery cells, such as too high currents, excessive mechanical forces on the cell housing or on the contacts, overcharging or overdischarging or too high and too low

Cell voltage, or too high and too low cell temperatures shifts the electrochemical equilibrium in the cell and the cell can in one

critical condition advised. In addition, the cell may be due to aging

Degeneration mechanisms also get into critical states. The critical state can lead to capacity losses, to increase the internal resistance, or to exothermic processes. These in turn can pose dangers not only to the equipment but also to people. Recent examples are the battery problems in the Galaxy Note 7 from Samsung or the burning

Battery pack in the Boeing 787 Dreamliner. An early detection is therefore desirable to be able to take countermeasures before this

Batteries pose a danger.

It is known to measure the state of charge (so-called state of charge SOC) and internal resistance of a battery by measuring electrical variables such as current and voltage, and from this the aging and health status

(so-called State of Health SOH). In addition, invasive

Methods used to gain insight into the chemical composition and construction of the cell. The associated interventions cause the battery to age prematurely or lead to direct destruction. Non-invasive procedures were then developed to determine the state of charge by sending and receiving bulk acoustic waves

possibly determine the condition of the battery. The main disadvantage of the above method is that the measured

Volume waves have a low sensitivity to material changes and impurities that are critical for a critical state. The reason for this is the small size of a wave packet compared to the

Battery cell and, consequently, a small interaction area. Thus, a large impurity (physical change, or gas amount) is necessary to obtain a significant change in the measurement signal, so impurities. Thus, this method is insensitive and susceptible to small impurities, but which can be critical for the life or the state of the battery cell.

It would therefore be desirable to have a diagnostic capability that does not damage the battery cell and does not suffer from the disadvantages of the prior art.

Summary of the invention It is therefore an object of the present invention to provide a diagnostic facility that does not damage the battery cell and overcomes the disadvantages of the prior art.

This object is achieved by a diagnostic device for determining critical changes in physical properties compared to a desired state in battery cells with a structure of several layers, wherein the layers are interconnected by a frictional connection, with at least one receiver and optionally in addition a transmitter for placement on Housing and / or cell contact of the battery cell, wherein the receiver is adapted to receive acoustic plate waves and / or acoustic torsional waves and a corresponding signal to an evaluation unit

transmit, which is intended to evaluate one or more parameters that are characteristic of an actual state of the battery cell, and to compare them with at least one previously defined threshold, wherein an exceeding or falling below the threshold value as an identification of

Battery cells with critical change in their physical properties is evaluated, in the case of the diagnostic device with transmitter, the transmitter is adapted to the acoustic record waves and / or the acoustic

To stimulate torsional waves in the battery cell with a propagation direction along the layers.

The term "critical change of physical properties" is understood to mean the achievement of a critical state in which, for example, the formation of gases and the pressure changes in the battery cells can lead to a defect or destruction of the battery, which usually results from a decomposition of the electrolyte in some gaseous components and

Reaction products in the battery cell, which are neither thermally nor electrically detectable in the early phase. These gaseous components and reaction products are highly flammable on the one hand and on the other hand lead to an increase in pressure within the battery cell and this in turn to mechanical stresses in the cell housing, since the battery cell is surrounded by a gas-tight cell housing, from which the gases can not escape. This can vary depending on the type of housing and the tension of the battery cell Battery system can lead to a strong or weak deformation of the cell housing, which is generally referred to as "puffing." Furthermore, aging mechanisms can cause electrolyte decomposition, which leads to critical changes, even with internal short circuits, which are caused by mechanical effects or by metallic lithium dendrites , the battery cell may change critically.

By battery cells is meant electrochemical cells, the electrical

Can store and provide energy. Batteries in the sense of this invention are batteries with a construction of several layers, wherein the layers are connected to one another with a frictional connection. It belongs to it

commercially available batteries, e.g. Lithium Ion Batteries, Nickel Metal Hydride (NiMH) Accumulators and Electrochemical Capacitors. By sender or receiver is meant any suitable transmitter and receiver for transmitting and receiving / receiving any type of acoustic plate wave and acoustic torsion wave. These include e.g. Wedge converters (angle probes in ultrasonic measurement), interdigital transducers with piezoelectric plates as well as certain laser excitations etc.

By "acoustic waves" is meant a reproduction of local

Pressure disturbances and particle shifts in an elastic medium.

Acoustic record waves, in contrast to bulk acoustic waves, which require an unrestricted propagation medium through the

Interfaces of the "plates" influenced.The layers within the battery cells can be considered as such interfaces

Plate waves include Lamb waves, horizontally polarized shear waves (HPSW), and vertical polarized shear waves (VPSW), among others. For the differentiation between the different types of waves, coordinates are defined for the different wave components. Coordinate x stands for the main propagation direction of the incident wave along the layers. The plane x-y denotes the plate plane, ie the plane of the layers in the plane

Battery cell. Perpendicular to the xy-plane is the propagation direction z. Lamb waves describe waves that have two propagation components, one of which extends in the propagation direction x (longitudinal) and the other perpendicular to it along the propagation component z (transverse). The direction of propagation of the wave in the plane of the xy-plane is to be considered. HPSW run horizontally in the plane of the plate (xy plane) perpendicular to the propagation direction along the propagation component y.

This can be described as a transverse wave. VPSW also run perpendicular to the propagation direction along component z, which is orthogonal to the plate plane (x-y plane). They are virtually out of the plate plane.

The difference to bulk waves is in the interface conditions.

While the wave type "bulk wave" is not restricted by interfaces and can unfold freely in the medium, the wave pattern "plate wave" is limited by at least two interfaces (the two faces of the "plate") , also called wave modes, as at

Volume waves, which in the detection of impurities in the

Battery cells is of enormous advantage. "Acoustic record waves" and

"Plate waves" are treated here as synonyms.

Torsional waves, also called cylinder waves, are understood to mean waves that start from a straight line in a homogeneous and isotropic medium. They expand similar to the Lamb waves, except that as interfaces

Cylinder jacket surfaces are considered instead of the plate surfaces. In addition, cylinder waves can propagate in hollow cylinders or tubes. Also, the HPSW and VPSW equivalent torsional waves are possible, the one

Have component perpendicular to the propagation direction. As a result, torsion waves, like disk shafts, have a greater variety

Propagation directions as bulk waves and are therefore better suited to detect defects in the battery cell. "Acoustic torsional waves" and "torsional waves" or "cylindrical waves" are treated here as synonyms. In contrast to the prior art, the present invention is based

essentially on guided ultrasonic waves (the above-mentioned plate and torsion waves). These waves propagate within the individual layers in the battery cell; In other words, the waves are guided by the individual layers of the battery cell. Only in this way is it possible to couple the waves to the battery cell at a first location and to receive them at a second location of the battery cell such that the second location does not have to lie on the acoustic axis of the sensors. Because when the guided waves propagate along the individual layers that act as waveguides, they interact with the respective adjacent layers (adjacent layers of the battery cell). This interaction results in changes of the original ones

Propagation parameters that can then be captured and evaluated. In the prior art, only waves for the detection of

Battery states are impressed only in the volume of the battery cell, so that only volume waves can propagate in the electrochemical storage.

Accordingly, the present invention provides a much more precise and

direction-independent way to measure states and changes in battery cells. For example, an evaluation unit is understood to mean a processor, a chip, a server, any unit that is capable of implementing and executing a computer program in order to evaluate the measured parameters.

Parameter is anything that characterizes the measured signal. These include, among other things, the transit time and the amplitude of the signal. From these parameters it is also possible to determine the frequency spectrum, the amplitude of the amplitude amplitude or the amplitude amount, the short-time Fourier transformation (STFT), the wavelet transformation (WT) and the energy of the signal.

Wedge converters are a widespread, monomodal

Converter configuration with which the insonification angle can be controlled. In ultrasonic technology, this is often used in the form of angle probes. These transducers consist of a wedge, which spans a wedge angle α between the upper wedge surface and the surface of the object to be measured, on which the wedge is mounted, and on whose upper side a piezoceramic is coupled. The ceramic is designed as a plate or disc. The

Piezoceramic excites a wave with a desired wavelength in the wedge. The wedge ensures that this wave at a certain angle to the

Plate surface meets and there a harmonious, spatially limited

Induced strain distribution. By reducing the shape of the strain distribution to the wavelength, e.g. a Lamb wave, this wave can be selectively excited and received. The tuning of the wavelengths is done via the wedge angle a, which can be calculated using the law of refraction.

The wedge converter thus has the advantage that different types of waves can be controlled by a variation of the wedge angle. In addition, the converter only transmits a unidirectional propagation field of Lamb waves, thereby

Reflections in the plate structure can be minimized.

Interdigital transducers are understood to mean mode-selective transducers whose operating principle is based on so-called surface acoustic wave filters which emit and receive Rayleigh waves and are used in telecommunications for frequency filtering. The interdigital transducer is composed of two comb-like, interdigitated electrodes with different polarity. In the present invention, the comb-like structure is disposed on electrodes parallel to the surface of the battery cell. Lamb waves propagate with comparatively large wavelengths, so that the electrodes must be made relatively long so that the electric field is generated in the thickness direction. As a material for the interdigital transducer both piezoceramic plates and PVDF films are used. When applied flatly to the plate structure, the structured electrodes cause the transducers to induce a spatially varying, finite strain distribution on the plate surface. When the distances of the electrodes are tuned to the wavelength of a mode and the transducers are operated at one frequency, it is possible to to selectively stimulate or receive a particular mode. This ensures precise control of the desired shaft type (Lamb, HPSW, VPSW).

The diagnostic device according to the present invention provides a diagnostic capability that does not damage the battery during diagnosis and overcomes the disadvantages of the prior art.

When using batteries can often have a limited storage space for

Including the battery in the housing may be an obstacle to the attachment of external sensors. Therefore, it is desirable that the

Diagnostic device takes up as little space as possible. To save not only space, but also material, is in one embodiment of the

Sender also the receiver. In this case, the wave traverses one

maximum distance from the transmitter back to the receiver, which means that the wave packets have a large interaction surface and which leads to a significant change in the measurement signal.

In one embodiment, the transmitter is an interdigital transducer having comb-like interdigitated electrodes with spaces between the electrodes equal to a predetermined wavelength. The flat shape of interdigital transducers allows to be mounted very space-saving to the housing of the battery cells.

In one embodiment, the transmitter is a wedge converter wherein the angle of incidence of the transmitter is selected so that the incident wave is refracted at a 90 ° angle in the wave propagation direction and thus transmits into the layers of the battery cell. In general, there are two critical angles, one for

Longitudinal waves and one for transverse waves. Deviating angles are also possible because the waves in the layers of the battery cell are less effectively excited. The same applies to wedge converters as receivers. These

Wedge converters, also called angle probes, are conventionally used in the

Ultrasonic measuring technology and have the advantage of variable designs and sizes. Also, these, which are determined by a fixed wavelength, can be set very easily at the desired angle. Thus, the

Excitation of all acoustic waves possible with only one transmitter. The critical angle can be determined by Snellius' law.

In a further embodiment, the transmitter is an ultrasonic sensor.

Ultrasonic sensors are known to be suitable for elastic waves

to stimulate and receive. They detect the desired distance by means of ultrasonic waves. The head of the sensor emits an ultrasonic wave, which comes from all positions of the battery cell (including housing depending on where the

Sensor is located) is reflected back. The time between transmission and reception of the ultrasonic wave is measured. Unlike an optical sensor, which has a transmitter and a separate receiver, the

Ultrasonic sensor be the same ultrasonic element for transmitting and receiving. In a reflection-type ultrasonic sensor, the ultrasonic waves are alternately transmitted from and to a single oscillator

receive. As a result, the sensor head can be kept very small. Other transmitters that can be used instead of ultrasonic sensors are piezoelectric ceramics and PVDF piezoelectric films.

In a further embodiment, the ultrasonic sensor excites with the aid of at least one piezoelectric element and / or at least one electromagnetic acoustic transducer and / or one or more laser excitations and / or at least one interdigital transducer

Plate waves and / or torsional waves on. In this case, have piezoelectric

Elements which are e.g. Piezoelectric ceramics or foils are very good electromechanical couplings. Together with electromagnetic acoustic transducers they generate a good relationship between

electrical voltage input and mechanical voltage out and vice versa.

In a further embodiment, the transmitter is a piezoelectric thickness or shear oscillator to be applied under adhesion to the battery cell. Acoustic record waves and torsion waves can be through directly under The propagation of the waves in the longitudinal direction of the individual battery layers is carried out by the transverse contraction, which is described with by transverse contraction number (Poisson's number), on the battery cell applied piezoelectric thickness and shear oscillator.

Laser excitation and electromagnetic acoustic transducers provide non-contact excitation, which is advantageous in some situations. Interdigital converters have the advantage of being very flat on the housing

Battery cell to lie, whereby the volume of a battery cell with transmitter hardly differs from the volume of only one battery cell without a sensor.

The plate waves excited by the various embodiments are either lamb waves, horizontally polarized shear waves or vertically polarized shear waves. Disk shafts are not mistaken with

Surface waves or bulk waves. While the wave wave volume wave is not limited by any interfaces and can unfold freely in the medium and the wave type surface wave is limited only by an interface, the wave type plate wave is limited by at least two interfaces (the two faces of the plate). This results in plate waves much more different and differentiated propagation possibilities than at

Volume waves, which in the detection of impurities in the

Battery cells is of enormous advantage. "Acoustic record waves" and

"Plate waves" are treated as synonyms here.The characterizing polarization directions of the Lamb waves, HPSW and VPSW enable the detection of different impurities in the material.With the selection of one of these wave types as the main excitation, a specific type of defect can be accurately and precisely measured can in turn lead to a targeted and accurate diagnosis of a defect in the battery cell.

Also, the excited plate waves may be any combination of Lamb waves, horizontally polarized shear waves and vertically polarized

Be shear waves. Different disk waves characterize different ones Changes in the battery cell. Therefore, with a combination of different plate waves a more accurate evaluation of the

Overall state of the battery can be determined because various physical effects can be identified in a measurement.

In a further embodiment, the excitation of the plate waves and / or torsional waves takes place continuously or in pulse form. With continuous excitation, it is possible to detect (immediately) changes in physical properties in real time. However, this suggestion has the disadvantage that steady energy consumption is necessary. With a pulse-shaped excitation is sent selectively, which makes the diagnostic device more energy efficient. In this case, the pulsed excitation in the considered time ranges can meet the required real-time criteria.

In a further embodiment, the transmitter is equipped to

To stimulate plate waves and / or torsional waves with a frequency of 100 kHz to 10 MHz in the battery cell. The low frequency range is defined between approx. 100 kHz and 500 kHz. Low-frequency waves are less damped by the individual layers and thus have a high amplitude during the measurement. However, due to the reflection at the interfaces (layers), these have weaker interaction with possible impurities. This in turn leads to less sensitivity to errors in the material as opposed to high frequency waves. High frequency waves start at one MHz. These are more dampened, but have much better sensitivity with respect to the detection of defects in the material. Especially a combination of both can be specifically used to obtain more accurate diagnoses.

In detail, due to the dispersion properties of the material, the low-frequency waves interact in another way with possible changes in the battery cell as high-frequency waves. This generally leads

different frequencies to different sensitivity to different material changes. Depending on the change, this can lead to a higher sensitivity at low frequencies. this applies also for high frequencies. For example, high-frequency waves are more affected or attenuated by spatial defects than low-frequency waves, and thus have a higher sensitivity to local ones

Changes in the battery cell. It is therefore beneficial both

To use high-frequency as well as low-frequency waves in order to detect different changes or defects in the battery cell accurately and thereby get an even more precise diagnosis result.

In a further embodiment, the excitation consists of a

Frequency spectrum with different frequencies. This allows a closer examination of the battery cell, as different frequencies can detect different defects.

Furthermore, in order to solve the technical problem, a battery system with diagnostic function comprising a battery cell with a structure of several layers, wherein the layers are interconnected by a frictional connection, and a diagnostic device according to claim 1 for determining critical changes in physical properties against a target Condition in battery cells, with at least one receiver and possibly also a transmitter, for arrangement on the housing and / or cell contact the

Battery cell, wherein the receiver is adapted to receive acoustic plate waves and / or acoustic torsional waves and to transmit a corresponding signal to an evaluation unit, which is intended to evaluate one or more parameters that are characteristic of an actual state of the battery cell, and to compare these with at least one previously defined threshold, wherein exceeding or falling below the threshold value as an identification of battery cells with critical change their

physical properties is evaluated, in the case of

Transmitter diagnostic device is adapted to excite the acoustic plate waves and / or the torsional acoustic waves in the battery cell with a propagation direction along the layers.

The use of the battery system offers many advantages. The battery cells can eg from the production on your aging or health status to be monitored. The same applies to battery modules and battery packs. It is possible during monitoring to detect the electrical and thermal parameters (such as cell temperature). From the measured parameters, the state of the battery cells can be determined with the aid of algorithms. When exceeding or falling below certain thresholds, such as

For example, the minimum and maximum signal voltage, a critical condition can be detected early. Thereafter, appropriate active and passive countermeasures can be taken to minimize hazards and losses.

In one embodiment of the battery system, at least one of the transmitters and at least one of the receivers are arranged on a same battery cell side. As the "same" battery cell side applies, if the shortest distance between (at least) two places, for sending and receiving

are selected, passing through only one layer / includes / tangent. By this arrangement, an increased amplitude is measured, since the shaft

mainly along the surface and has to go through fewer interactions. With changes in the physical properties of the battery cell compared to the desired state such. Gas Formations in the

Battery cell, the amplitude of the measurement signal increases because the impurity, e.g. a bubble of gas that reflects the wave back again. Exceeding a threshold value is therefore an indicator of a physical change, e.g. in the form of a glass bubble, in the battery cell.

In a further embodiment of the battery system, at least one of the transmitters and at least one of the receivers are at different

Battery cell sides arranged. The term "different" battery cell sides applies when the shortest distance between (at least) two locations selected for transmission and reception passes through several layers, due to the frictional connection between the layers in the battery cell

(Pressed) connect, a good propagation of the wave is guaranteed by the layers. The good transfer from one battery cell side to the other Page is reduced by an impurity in the material. Falling below a threshold value can therefore be an indicator of a change in the

Battery cell be. Sender and receiver are preferably not opposite, but offset in the direction of propagation of the wave at the

Battery cell arranged. In the case of gas formation, the receiver, which is offset from the transmitter (for example, on the other side), receives a weakened signal because energy is reflected by the trapped gas toward the transmitter.

In one embodiment of the battery system, at least one of the transmitters and at least one of the receivers are arranged on the same cell contact or on different cell contacts. The cell contact is the "same" cell contact, if it is the same pole of a battery cell.

Cell contacts are "different" cell contacts when the sensors are on

different poles are attached. Often, the environment for embedding the battery makes it difficult to attach sensors to the battery cell sides. To solve this problem, the sensors are attached to the cell contacts of the battery. By sending the shaft, the measured signal can also provide information about the adhesion of the coating of the electrodes inside the battery cell. When both all transmitters and receivers are mounted on the same cell contact, exceeding a threshold value is an indicator that changes, such

Gas formations occur inside the battery cell. If the stations and

Receivers mounted on different cell contacts will become one

Falling below a threshold as a change of physical

Properties scored.

In one embodiment of the battery system, at least one of the transmitters on a battery cell side and at least one of the receivers on a cell contact and vice versa are mounted. The advantage is that in some situations, only this configuration is allowed. Falling below a threshold value can be considered an indicator for the change of physical properties in the battery cell in this arrangement. The invention further relates to a method for diagnosing changes in physical properties with respect to a desired state of battery cells having a structure of a plurality of layers, the layers being interconnected by a frictional connection

arranging at least one receiver on the housing and / or

Cell contact of the battery cell,

receiving acoustic plate waves and / or acoustic torsional waves by the receiver,

a transmission of a corresponding signal by the receiver to an evaluation unit,

an evaluation of one or more parameters which are characteristic of an actual state of the battery cell, by the evaluation unit, a comparison of the evaluated parameters with at least one predefined threshold value,

a value of exceeding or falling below the

Threshold as identification of battery cells with change in physical properties.

The method also provides the possibility of material properties of

Derive battery cell. These include: the average pressure inside the cell, modulus of elasticity, shear modulus, density, layer height, solid to liquid phase transitions, liquid to solid, solid to gaseous, liquid to gaseous and gaseous to liquid. In addition, changes in the mechanical structure can be detected, such as the delamination between

various layers of the battery such as active material and arrester and / or the delamination of the contact lugs (cell contacts) and / or the delamination of individual layers of the contact lug.

An embodiment of the method provides in addition to the receiver

at least one transmitter for exciting acoustic plate waves and / or torsion waves in the battery cell with a propagation direction along the layers, which is arranged on the housing and / or cell contact of the battery cell available. This enables active transmission of the wave to be measured. In this case, transmitter and receiver are preferably not opposite, but offset in the propagation direction of the shaft to the battery cell.

An embodiment of the method includes that the evaluating the

Parameter amplitude and duration of the signal includes. These received signals can be evaluated with different methods. It is possible to use both analog and digital filters. From the

Measurement signals can be, inter alia, the energy, the frequency, the integral of the amplitude square or the amplitude amount, the frequency spectrum of the entire signal by the Fourier transform or the fast Fourier transformation, the frequency spectrum in the individual areas through the

Short-term Fourier transform, which determines the pulse spectrum in the individual regions of the signal by the wavelet transformation. The mathematical methods for the various transformations / methods may be a combination of different window functions, such as e.g. Rectangle windows, Von-Hann windows, Hamming windows, Gaussian windows, Blackman windows, Blackman-Harris windows, Blackman-Nuttal windows, Flat-top windows, Bartlett windows, Bartlett-Hann windows, Cosine window, Tukey window,

Lanczos windows, Kaiser windows, Gaussian windows etc.

The obtained measurement results can be stored and a change of the measurement results over time can be compared with each other. These can be evaluated with stochastic methods to evaluate the change in the physical properties of a battery cell over time. One embodiment of the method is the generation of a prognosis of the physical changes, preferably temperature changes, in the battery cell in the future by evaluating the parameters over time. By evaluating the measurement results over time, critical events in particular should be forecast at an early stage, such as short-term ones

Changes in physical properties are identified and evaluated.

In a further embodiment of the method, the state of charge of Battery cell determined by the ultrasonic signals with the electric

Measuring signals are correlated.

Brief description of the illustrations

These and other aspects of the invention are shown in detail in the figures as follows:

FIG. 1: Battery system with diagnostic function, comprising a battery cell with a construction of several layers and the diagnostic device according to the invention.

Fig.2: Diagnostic device for determining critical changes in physical properties against a desired state in battery cells.

3: Arrangement wedge converter for transmitting and / or receiving

acoustic plate and / or torsion waves on the battery.

Fig. 4: interdigital transducer with comb-like electrodes.

Fig. 5: Method for diagnosing change of physical

Properties versus a nominal state of battery cells.

Fig.6: Course of a measurement signal measured using the

Inventive diagnostic device and use of the method according to the invention.

Detailed description of the embodiments

Fig. 1 shows a battery system 50 with diagnostic function comprising a

Battery cell 12 having a structure of a plurality of layers 14, wherein the layers 14 are interconnected by a frictional connection, and a

The diagnostic system 10 according to the invention for determining critical changes in physical properties compared to a desired state in battery cells 12. The battery system 50 includes at least one receiver 18 and optionally additionally a transmitter 16, for placement on the housing 20 and / or cell contact 22 of the battery cell 12. The receiver 18 is adapted to receive acoustic plate waves 24 and / or acoustic torsional waves 26 and to deliver a corresponding signal 28 to an evaluation unit 30 to transfer. The evaluation unit 30 is provided for evaluating one or more parameters 32 that are characteristic of an actual state of the battery cell 12 and that have at least one previously defined one

Threshold 34 to compare. In this case, exceeding or falling below the threshold value 34 as identification of battery cells with critical

Changed their physical properties. in case of a

Battery system 50 with transmitter 16, the transmitter 16 is suitable, the

acoustic plate waves 24 and / or the acoustic torsional waves 26 in the battery cell 12 with a propagation direction along the layers 14 to excite. The transmitter 16 can also be the receiver 18 at the same time. Furthermore, in the case of a battery system with transmitter 16, at least one of the transmitters and at least one of the receivers may be arranged on a same battery cell side 42, 20. Also, at least one of the transmitters and at least one of the receivers may be arranged on different battery cell sides 42, 20. Thus, the propagation parameters of the plate wave and / or

Torsional waves are also measured by the individual cell layers. In one embodiment, at least one of the transmitters and at least one of the receivers may be disposed on a same cell contact 22 or on different cell contacts 22. In a further embodiment, at least one of the transmitters on a battery cell side 42, 20 and at least one of the receivers may be mounted on a cell contact 22 and vice versa.

FIG. 2 shows a diagnostic device 10 for determining critical

Changes in physical properties with respect to a desired state in battery cells 12 with a structure of several layers 14, wherein the layers 14 are interconnected by a frictional connection. The diagnostic device 10 includes at least one receiver 18 and, optionally, additionally a transmitter 16, for placement on the housing 20 and / or cell contact 22 of the battery cell 12. The receiver 18 is adapted to receive acoustic plate waves 24 and / or acoustic torsional waves 26 and a corresponding one Signal 28 to transmit to an evaluation unit 30. The evaluation unit 30 is intended to evaluate one or more parameters 32, the

are characterizing for an actual state of the battery cell 12 and this with at least one previously defined threshold 34 to compare. In this case, exceeding or falling below the threshold value 34 is evaluated as an identification of battery cells with a critical change in their physical properties. In the case of a diagnostic device 10 with transmitter 16, the transmitter 16 is adapted to the acoustic plate waves 24 and / or the acoustic

Torsionswellen 26 in the battery cell 12 with a propagation direction along the layers 14 to excite. The transmitter 16 can simultaneously also the

Be recipient 18. The transmitter 16, 18 an interdigital transducer 36 with

comb-like interdigitated electrodes 38 having spacings between the electrodes 38 may be equal to a predetermined wavelength. In one embodiment, the transmitter 16, 18 is a wedge transducer 40, the transmitter 16, 18, 40 being oriented to penetrate the sheets 14 at a critical angle

Battery cell 12 can send. The transmitter 16, 18, 36, 40 can a

Be ultrasonic sensor. The ultrasonic sensor can with the help of at least one piezoelectric element and / or at least one

electromagnetic acoustic transducer and / or one or more laser excitations and / or at least one interdigital transducer the

Stimulate plate shafts 24 and / or torsional shafts 26. The excited ones

Disk shafts 24 may be either lamb waves or horizontally polarized shear waves or vertically polarized shear waves, or any combination of Lamb waves, horizontally polarized shear waves, and vertically polarized shear waves. The excitation of the plate shafts 24 and / or

Torsionswellen 26 can be continuous or pulsed. The transmitter 16, 18, 36, 40 may further be equipped so that plate waves 24 and / or torsional waves 26 having a frequency of 100 kHz to 10 MHz in the

Battery cell to be stimulated. Furthermore, an excitation from a

Frequency spectrum with different frequencies exist.

3 shows a battery system 50 having a wedge transducer 40 for transmitting and / or receiving acoustic plate shafts 24 and / or torsion shafts 26, wherein the transmitter wedge transducer 40 may be oriented to penetrate at a critical angle into the layers 14 of the battery cell 12 sends. The wedge converter 40 consists of a wedge which has a wedge angle α between the upper wedge surface 48 and the surface of the object to be measured, on which the wedge is mounted, spans and on the upper side of which a piezoceramic is coupled. The ceramic is designed as a plate or disc. The piezoceramic excites a wave with a desired wavelength in the wedge. The wedge ensures that this wave hits the plate surface at a certain angle and induces a harmonic, spatially limited strain distribution. By tuning the shape of the strain distribution to the wavelength, eg a Lamb wave, this wave type can be selectively excited and received. The

Tuning of the wavelengths is done via the wedge angle a, which can be calculated using the law of refraction. For the suggestion of

Lamb waves can be used to vibrate and excite HPSW and VPSW shakers.

Fig. 4 shows an interdigital transducer 36 as a transmitter 16, 18, 36, 40 with comb-like, interdigitated electrodes 38 with different polarity, the distances between the electrodes 38 may have a predetermined wavelength. In the present invention, the comb-like structure is arranged on electrodes 38 parallel to the surface of the battery cell 12. As a material for the interdigital transducer 36 both piezoceramic plates and PVDF films are used. When applied flatly to the plate structure, the structured electrodes 38 cause the transducers 36 to induce a spatially varying, finite strain distribution on the plate surface. When the pitches of the electrodes 38 are tuned to the wavelength of one mode and the transducers 36 are operated at one frequency, it is possible to selectively excite a particular mode. This ensures precise control of the desired shaft type (Lamb, HPSW, VPSW). However, it is also possible to use a piezoelectric thickness or shear oscillator (piezoelectric plate) which is applied under force to the battery cell 12. The excitation in the direction of propagation along the battery electrode is effected by the transverse contraction (Poisson's number).

FIG. 5 shows a method 100 for diagnosing changes in physical properties compared with a desired state of battery cells 12 with a Structure of several layers 14, wherein the layers 14 are interconnected by a frictional connection. The method comprises placing 1 10 of at least one receiver on the housing and / or cell contact of the battery cell, receiving 130 acoustic disk waves and / or acoustic

Torsionswellen by the receiver, a transmission 140 of a corresponding signal by the receiver to an evaluation, an evaluation 150 of one or more parameters that characterize an actual state of the

Battery cell are through the evaluation unit, comparing 160 of

evaluated parameters with at least one predefined threshold value and a value 170 of exceeding or falling below the

Threshold as identification of battery cells with change of

physical properties. In addition, the method 100

at least one transmitter for exciting 120 acoustic disk waves and / or torsion waves in the battery cell with a propagation direction along the layers, which is arranged on the housing and / or cell contact of the battery cell include. The evaluation 150 of the parameters 32 may include an amplitude 44, 32 and a delay 46, 32 of a signal 28. Furthermore, a

Forecast 180 of the physical changes of the battery cell in the future may be created by evaluating the parameters 32 over time.

FIG. 6 shows the course of a measuring signal measured using the diagnostic device 10 according to the invention and using the measuring device according to the invention

Method 100 according to the invention. The parameter amplitude (both positive and negative) 44, 32 can be defined as threshold value 34. Run time 46, 32 is referred to as the time it takes for the sent signal to reach the receiver.

The embodiments shown here are only examples of the present invention and therefore should not be understood as limiting.

Alternative embodiments contemplated by one skilled in the art are equally within the scope of the present invention. List of reference numbers

10 diagnostic device according to the invention

12 battery cell

14 layers (the battery cell)

16 stations

18 recipients

20 housing

22 cell contact

24 acoustic plate wave

26 acoustic torsion wave

28 signal

30 evaluation unit

32 parameters

34 threshold worth

36 interdigital transducer

38 comb-like interdigitated electrodes

40 wedge converters

42 battery cell side

44 amplitude

46 term

48 Upper wedge surface

50 battery system

100 method according to the invention

1 10 Arranging Receiver

120 excitation of acoustic plate and / or torsion waves

130 receiving acoustic plate waves and / or

acoustic torsional waves

140 transmitting a corresponding signal

150 Evaluate one or more parameters

160 Compare the evaluated parameters

170 values of exceeding or falling below the

Threshold values 180 Creating a Prediction of Physical Changes in the Battery Cell α Wedge Angle

Claims

claims:

1 . A diagnostic device (10) for determining critical

Changes in physical properties compared to a desired state in battery cells (12) with a structure of several layers (14), wherein the layers (14) are interconnected by a frictional connection, with at least one receiver (18) and optionally in addition a transmitter (16 ) for placement on the housing (20) and / or cell contact (22) of the battery cell (12), the receiver (18) being adapted to receive acoustic plate waves (24) and / or torsional acoustic waves (26) and a corresponding signal (28) to an evaluation unit (30) intended to evaluate one or more parameters (32) characterizing an actual state of

Battery cell (12) are, and compare them with at least one pre-defined threshold (34), wherein an excess or

Falling short of the threshold value (34) is evaluated as identification of battery cells with a critical change in their physical properties, wherein in the case of the transmitter-based diagnostic device, the transmitter (16) is adapted to the acoustic plate waves (24) and / or the acoustic torsional waves (26) in the battery cell (12) with a

Propagation direction along the layers (14) to stimulate.

2. The diagnostic device (10) according to claim 1,

characterized,

the transmitter (16) is also the receiver (18).

3. The diagnostic device (10) according to claim 1 or 2,

characterized,

in that the transmitter (16, 18) comprises an interdigital transducer (36) with comb - like, interdigitated electrodes (38) with spaces between them

Electrodes (38) is equal to a predetermined wavelength.

4. The diagnostic device (10) according to claim 1 or 2, characterized,

the transmitter (16, 18) is a wedge transducer (40), the transmitter (16, 18, 40) being oriented so that it can transmit at a critical angle into the layers (14) of the battery cell (12).

5. The diagnostic device (10) according to claim 1 or 2,

characterized,

in that the transmitter (16, 18) is a piezoelectric thickness or shear oscillator to be applied with force fit to the battery cell (12).

6. The diagnostic device (10) according to one of the preceding claims, characterized

that the transmitter is an ultrasonic sensor.

The diagnostic device (10) according to claim 6,

characterized,

that the ultrasonic sensor with the help of at least one

piezoelectric element and / or at least one

electromagnetic acoustic transducer and / or one or more laser excitations and / or at least one

Interdigital transducer which excites plate waves and / or torsion waves.

The diagnostic device (10) according to any one of the preceding claims, characterized

the excited plate waves are either lamb waves or horizontally polarized shear waves or vertically polarized shear waves.

The diagnostic device (10) according to any one of claims 1 to 7,

characterized,

the excited plate waves are any combination of Lamb waves, horizontally polarized shear waves and vertically polarized

Shear waves are.

10. The diagnostic device (10) according to any one of the preceding claims, characterized

that the excitation of the plate waves and / or torsional waves

continuous or pulsed.

1 1. The diagnostic device (10) according to one of the preceding claims, characterized

that the transmitter is equipped to the disk waves and / or

Torsional waves with a frequency of 100 kHz to 10 MHz in the

To stimulate the battery cell.

The diagnostic device (10) according to one of the preceding claims, characterized

the excitation consists of a frequency spectrum with different frequencies.

13. A battery system (50) with diagnostic function comprising a battery cell (12) having a structure of a plurality of layers (14), wherein the layers (14) are interconnected by a frictional connection, and a

Diagnostic device (10) according to claim 1 for the determination of critical

Changes in physical properties compared to a desired state in battery cells (12), with at least one receiver (18) and possibly also a transmitter (16), for arrangement on the housing (20) and / or cell contact (22) of the battery cell (12), wherein the receiver (18) is adapted to acoustic plate waves (24) and / or acoustic

Torsionswellen (26) receive and transmit a corresponding signal (28) to an evaluation unit (30) which is intended to evaluate one or more parameters (32) which are characteristic of an actual state of the battery cell (12), and to compare these with at least one previously defined threshold value (34), wherein an exceeding or

Falling below the threshold value (34) is evaluated as identification of battery cells with a critical change in their physical properties, wherein in the case of the diagnostic device with transmitter, the transmitter (16) suitable for this purpose, the acoustic plate waves (24) and / or the acoustic torsional waves (26) in the battery cell (12) with a

Propagation direction along the layers (14) to stimulate.

The battery system (50) according to claim 13,

characterized,

in that at least one of the transmitters and at least one of the receivers are arranged on a same battery cell side (42, 20).

The battery system (50) according to claim 13,

characterized,

in that at least one of the transmitters and at least one of the receivers are arranged on different battery cell sides (42, 20). 16. The battery system (50) according to claim 13,

characterized,

in that at least one of the transmitters and at least one of the receivers are arranged on the same cell contact (22) or on different cell contacts (22).

17. The battery system (50) according to claim 13,

characterized,

at least one of the transmitters on a battery cell side (42, 20) and at least one of the receivers are mounted on a cell contact (22) and vice versa.

A method (100) for diagnosing changes in physical properties against a desired state of battery cells (12) having a multi-layered structure (14), the layers (14) being interconnected by a frictional connection

arranging (1 10) at least one receiver on the housing and / or cell contact of the battery cell,

receiving (130) acoustic disk waves and / or acoustic torsional waves through the receiver, transmitting (140) a corresponding signal through the

Receiver to an evaluation unit,

an evaluation (150) of one or more parameters which are characteristic of an actual state of the battery cell, by the evaluation unit,

comparing (160) the evaluated parameters with at least one predefined threshold value,

a value (170) of exceeding or undershooting the threshold value as identification of battery cells

Change in physical properties.

The method (100) according to claim 18,

characterized,

in addition, at least one transmitter for exciting (120) of

acoustic disk waves and / or torsion waves in the battery cell with a propagation direction along the layers, on the housing and / or cell contact of the battery cell is arranged. 20. The method (100) according to claim 18,

characterized,

in that the evaluation (150) comprises the parameters (32) an amplitude (44, 32) and a transit time (46, 32) of the signal (28).

The method (100) according to claim 20,

characterized,

that a prognosis (180) of the physical changes,

preferably temperature changes, the battery cell is created in the future by evaluating the parameters (32) over time.