Device and method for performing measurements on a battery cell

Abstract

The invention relates to a circuit (20, 21) which enables a first voltage present in a battery cell (1) to be determined, the circuit comprising: an oscillating circuit (8) having a coil (26) and a component (24) whose capacitance depends on the voltage applied to the component, and a reference electrode (7). The component may be a varactor diode. Also disclosed are a method, a battery cell and a component having a further circuit outside the battery cell housing, the further circuit being used to read out the first voltage present in the battery cell.

Description

Technical Field

[0001] The invention relates to a device and a method for performing measurements on a battery cell. The invention relates in particular to the determination of the voltage present in a battery cell or battery. Background Art

[0002] The invention is used in particular in vehicle batteries (and the battery cells contained therein), wherein this may be, for example, a high-voltage accumulator which is used to drive the vehicle, but also a conventional vehicle battery which is not designed to actually drive the vehicle but, for example, enables starting of the vehicle's internal combustion engine. Although use in connection with vehicle batteries is preferred, the invention is not necessarily limited to this aspect and can in principle also be used in other batteries and battery cells.

[0003] For various reasons, it is often desirable to determine the voltage of a cell or the half-cell potential of a half-cell in a cell. It is known that one or more reference electrodes can be introduced into the cell for this purpose, so that the cell can be operated more reliably and with a higher power and (when used as a drive for a motor vehicle) a greater range. When operating with such reference electrodes, better results are obtained at low input currents of the measuring device, since otherwise the potential may not remain stable and the reference electrode may drift away. To solve this problem, an electrode array with a plurality of reference electrodes is proposed, for example, in US Pat. No. 8,586,222.

[0004] The inventors of the present invention have recognized that in the previously known methods, in which a reference electrode or a plurality of reference electrodes are used to determine the voltage within a battery cell, additional terminals are required, that is, in addition to the two terminals that are usually present (positive and negative poles of the battery cell). In this regard, the inventors have recognized that for the additional terminals, additional electrical connections must also be led through the battery cell housing, so that the voltage inside the battery cell (which voltage is to be determined via the reference electrode) can be read out via a suitable circuit or measuring device outside the battery cell. In this regard, the inventors have also recognized that additional electrical connections through the battery cell housing can lead to higher housing costs, weakening of the housing and to a greater need for installation space. In particular, in the case of reference electrode arrays (as disclosed in US Pat. No. 8,586,222), it is necessary to individually control and recharge the individual reference electrodes of the array, so that even multiple electrical connections through the battery cell housing are required. Summary of the invention

[0005] Against this background, it is an object of the present invention to provide an alternative, in particular improved device and an alternative, in particular improved method for determining the voltage present in a battery cell.

[0006] A first aspect of the present invention relates to a circuit capable of determining a first voltage present in a battery cell, the circuit comprising:

[0007] an oscillating circuit having a coil and a component whose capacitance depends on the voltage present at the component; and

[0008] - reference electrode,

[0009] The circuit is provided to be arranged in the housing of the battery cell in such a way that a first voltage present between the battery cell electrode and the reference electrode is at least partially applied to the component and the resulting resonant frequency of the resonant circuit can be detected outside the housing via the magnetic field of the coil.

[0010] Although the circuit for determining the voltage is provided within the battery cell, the circuit may also be provided separately for later installation in the battery cell.

[0011] By making the capacitance of the component dependent on the voltage applied to the component, the resonant frequency of the oscillating circuit can also be made dependent on the voltage applied to the component, because the resonant frequency of the oscillating circuit is particularly dependent on the capacitance and inductance of the components in the oscillating circuit. By means of a suitable readout circuit (which is particularly arranged outside the battery cell), the magnetic field of the coil can be detected outside the housing of the battery cell. From the detected magnetic field, the resonant frequency of the oscillating circuit can be determined, which in turn allows the voltage applied to the component to be inferred. The voltage (herein referred to as "first voltage" for better distinction) existing between the battery cell electrode (anode or cathode) and the reference electrode in the battery cell is not necessarily directly (i.e. undistributed) applied to the component. Alternatively, the first voltage can be distributed, for example, by a voltage divider, wherein a portion of the first voltage is then applied to the component. If it is known in which ratio the first voltage is distributed, the first voltage can be calculated from the determined voltage applied to the component. Therefore, it is ultimately possible to detect the magnetic field outside the housing of the battery cell, determine the resonant frequency of the oscillating circuit from the magnetic field, determine the voltage applied to the component from the resonant frequency of the oscillating circuit, and determine the first voltage in the battery cell from the voltage applied to the component. The first voltage determined in this way can be used for battery (cell) management, for example, to prevent battery cell overload, control charging of battery cells, monitor the state of charge of battery cells, etc.

[0012] According to one embodiment, the component has a diode, in particular a varactor diode.

[0013] Varactors are particularly suitable for use in the circuit according to the invention because they firstly have a capacitance that is dependent on the applied voltage and secondly because their diode characteristics can be advantageously used for recharging the reference electrode, as described in detail below. Other components are also conceivable, the capacitance of which is dependent on the voltage applied to them.

[0014] According to one embodiment, the resonant circuit has a capacitor which is connected in series with the component. The capacitor is suitable for preventing a possible short circuit via the coil of the resonant circuit.

[0015] According to one embodiment, the half-cell potential of the material of the reference electrode has a plateau, thereby enabling stable operation over a relatively large range of states of charge.

[0016] According to one embodiment, the reference electrode may, for example, have one or more of the following materials:

[0017] - Transition metal oxides, such as LiCoO 2 ;

[0018] -Mixed oxides, such as LiNi 1-y Co y O 2 ;

[0019] - Phosphates, such as LiMPO 4 , wherein M may be, for example, Fe, Mn, or Co;

[0020] -Metal;

[0021] and especially

[0022] -Lithium iron phosphate;

[0023] - lithium titanate;

[0024] - lithium manganese phosphate;

[0025] -Lithium-gold alloy;

[0026] -Lithium aluminum alloy.

[0027] The half-cell potential of this material has a plateau that is suitable for the present invention.

[0028] A second aspect of the present invention relates to a battery cell, comprising:

[0029] - a first battery cell electrode and a second battery cell electrode, the first battery cell electrode and the second battery cell electrode being located within the housing of the battery cell; and

[0030] A circuit as described above, which is also located in the housing of the battery cell, wherein the resonant circuit is connected to the first battery cell electrode and the reference electrode in such a way that the first electrical contact of the component is electrically connected to the first battery cell electrode and the second electrical contact of the component is electrically connected to the reference electrode.

[0031] In such a battery cell, the above-mentioned "first voltage" is applied between the first battery cell electrode and the reference electrode.

[0032] According to one specific embodiment, the resistor is electrically connected between the resonant circuit and the first battery cell electrode or between the resonant circuit and the reference electrode.

[0033] The current through the reference electrode can be limited by the resistor. For this reason, it is recommended to use a high-ohm resistor, for example a resistor in the megohm range, if necessary.

[0034] According to one embodiment:

[0035] a first battery cell contact accessible from outside the battery cell is electrically connected to a first battery cell electrode via a first electrical connection, which is led through the housing of the battery cell;

[0036] a second battery cell contact accessible from outside the battery cell is electrically connected to a second battery cell electrode via a second electrical connection which is led through the housing of the battery cell; and

[0037] No further electrical connections are passed through the housing of the battery cell.

[0038] The housing of such a battery cell is therefore not weakened by additional electrical connections passing through the housing.

[0039] A third aspect of the invention relates to an assembly for determining a first voltage present in a battery cell, the assembly comprising:

[0040] - a battery cell as described above;

[0041] A further circuit is arranged at least partially outside the housing of the battery cell and is provided to detect the resonant frequency of the resonant circuit via the magnetic field of the coil.

[0042] By enabling the further circuit to detect the resonant frequency of the resonant circuit via the magnetic field of the coil, the first voltage can ultimately be “read out” so that information, for example, about the charge state of the battery cell can be provided outside the battery cell.

[0043] According to one embodiment, the electric circuit and the further electric circuit are electrically insulated from one another. Here, the term "electrically insulated from one another" is preferably understood to mean that the electric circuit and the further electric circuit are not directly connected to one another, that is, the circuits are essentially influenced only by magnetic coupling. However, there is of course a connection of the electric circuit to other components of the battery cell, in particular to the first battery cell electrode, and the further electric circuit can be operated, for example, when used in a vehicle, via the same (vehicle) battery (cell), so that in this way there is an indirect electrical connection between the electric circuit and the further electric circuit.

[0044] A fourth aspect of the present invention relates to a battery comprising:

[0045] Two or more battery cells as described above; or

[0046] Two or more components as described above.

[0047] A fifth aspect of the invention relates to a method for determining a first voltage present in a battery cell, the method comprising:

[0048] - providing components as described above;

[0049] - detecting the resonant frequency of the oscillating circuit by means of the further circuit via the magnetic field of the coil; and

[0050] - determining a first voltage present in the battery cell based on the detected resonance frequency of the oscillating circuit.

[0051] The advantageous embodiments and specific embodiments mentioned with reference to one of the aspects of the invention (circuit, battery cell, assembly, battery and method) and their advantages also apply accordingly to the other aspects of the invention according to the invention.

[0052] Further advantages, features and possible applications of the invention are apparent from the drawings and the description of the drawings. All features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the drawings and / or shown individually in the drawings can be used not only in the respectively indicated combination but also in other combinations or individually, as long as these combinations are practicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention will now be explained in more detail with reference to some preferred exemplary embodiments and with reference to the accompanying drawings, wherein components having the same or similar functions are provided with the same reference numerals.

[0054] The drawings are partially shown schematically, in which:

[0055] Figure 1 shows components according to one embodiment of the present invention;

[0056] Figure 2 A circuit according to an embodiment of the present invention is shown;

[0057] Figure 3 A circuit according to another embodiment of the present invention is shown;

[0058] Figure 4 Graphical illustrations showing half-cell potentials for different materials;

[0059] Figure 5 A flow chart with the method steps of the method according to the invention is shown. DETAILED DESCRIPTION

[0060] Figure 1 A simplified diagram of an assembly 100 is shown having a battery cell 1 and a readout circuit 12 which is connected to a battery (cell) management system 13 .

[0061] In this embodiment, the battery cell 1 has a housing 2, which is made of a plastic material, for example, in order to seal the interior of the battery cell 1 in a gas-tight manner. An anode 3 is arranged in the housing 2, which is connected to an anode terminal 4 via an anode wire 9. The anode terminal 4 is accessible from the outside and is, for example, fixed to the surface of the housing 2 and / or at least partially integrated into the housing wall. Parts of the anode wire 9 and / or parts of the anode terminal 4 are guided through openings in the housing 2, so that an electrical connection between the interior of the housing 2 and the space outside the housing 2 can be achieved.

[0062] In a similar manner, a cathode 5 is arranged in the housing 2 , which cathode is connected to a cathode terminal 6 via a cathode lead 10 .

[0063] The battery cell 1 may be a lithium-ion battery cell, for example.

[0064] In addition to the anode 3 and the cathode 5, which are often collectively also referred to as working electrodes, main electrodes or simply as cell electrodes, a further electrode, namely a reference electrode 7, is provided in the housing 2. The reference electrode is connected to the anode 3 or the anode line 9 via an oscillating circuit 8 and a connecting line 11, which are described in detail below. In the present example, the circuit consisting of the reference electrode 7, the oscillating circuit 8 and the connecting line 11 forms a circuit which enables the (first) voltage present in the cell to be determined.

[0065] Instead of reading out the DC voltage of the reference electrode "directly" relative to one of the working electrodes by connecting the reference electrode to a further (third) terminal located outside the housing as in a known manner, in this embodiment the reference electrode 7 is connected relative to one of the working electrodes (at Figure 1The voltage difference at the anode 3 (in the example of FIG. 1 ) is used to detune the oscillating circuit 8 or to influence the resonant frequency of the oscillating circuit.

[0066] The following is based on Figure 2 and 3 The mode of action on resonant circuit 8 and the influence on the resonant frequency by the voltage difference between reference electrode 7 and anode 3 are described.

[0067] like Figure 1 As shown in FIG. 1 , a further circuit, namely a readout circuit 12, is arranged outside the housing 2 of the battery cell 1. The readout circuit 12 has a circuit known per se, by means of which the resonant frequency of the oscillating circuit 8 can be determined by magnetic coupling. Figure 1 , represented by the resonant circuit 8 and two oppositely disposed coils of the readout circuit 12. These coils are arranged as close to one another as possible, so that sufficient magnetic coupling can be achieved.

[0068] The voltage difference between the reference electrode 7 and the anode 3 can be determined from the resonance frequency of the oscillating circuit 8 determined by the readout circuit 12. If the electrical properties of the components of the oscillating circuit 8 and, if necessary, the electrical properties of the reference electrode 7 are known, the mathematical relationship between the determined resonance frequency and the voltage difference between the reference electrode 7 and the anode 3 can be determined purely by calculation / theoretically. However, it is recommended that, alternatively or additionally, a calibration is also performed.

[0069] The voltage difference between the reference electrode 7 and the anode 3 can be determined from the determined resonance frequency in the readout circuit 12 or by a component connected downstream, such as a battery (cell) management system 13. Ultimately, the determined voltage difference between the reference electrode 7 and the anode 3 can be used by the battery (cell) management system 13 to obtain information about the charge state of the battery cell 1. This information can be used by the battery (cell) management system for different purposes, for example to avoid overloading of the battery cell 1, to initiate recharging of the battery cell 1 or to control and, if necessary, optimize the use of the battery cell 1 for its intended purpose (e.g., driving of the vehicle).

[0070] Figure 2 A circuit 20 is shown, the upper portion of which corresponds to Figure 1 The circuit 20 further comprises a resonant circuit 8 in the circuit, and the lower part of the circuit corresponds to the reference electrode 7. The circuit 20 further comprises a resistor 22 which is connected between the resonant circuit 8 and the reference electrode 7.

[0071] The resonant circuit 8 of the circuit 20 has a coil 26 and a capacitor 28. Furthermore, the resonant circuit 8 has a further component 24, which in the example shown is a varactor diode 24.

[0072] The varactor diode 24 is a component whose capacitance is related to the voltage applied to the component. Figure 2 In the example of , the voltage is the voltage between the left terminal of the varactor 24 (which is connected to the resistor 22 and the capacitor 28, represented as point 23) and the right terminal of the varactor 24 (which is connected to the coil 26, point 25). Figure 1 The connecting wire 11 in the embodiment is also connected to the point 25 and ends at the point 30. The end point 30 corresponds to Figure 1 The point in the graph at which the connecting wire 11 is in contact with the anode wire 9 is conductive.

[0073] if Figure 2 The circuit 20 is in the battery cell 1 as Figure 1 , i.e. arranged in the battery cell housing 2 and connected to the anode conductor 9 via the point 30), a voltage difference (“first voltage”) exists between the reference electrode 7 and the point 30. A portion of this first voltage, depending on the size of the resistor 22 (which may lie in the megohm range, for example), is applied to the varactor 24, i.e. between the points 23 and 25. This voltage applied to the varactor 24 influences the capacitance of the varactor 24 and thus the total capacitance of the resonant circuit 8, which in a manner known per se is composed of the individual subcapacitances, i.e. in this case the capacitance of the capacitor 28 and the (transient, variable) capacitance of the varactor 24.

[0074] Since the resonant frequency of the oscillating circuit 8 is related to the total capacitance and the total inductance of the oscillating circuit 8 (coil 26), it is also related to the voltage difference between the reference electrode 7 and the point 30 or anode 3. The resonant frequency of the oscillating circuit 8 can be determined as follows: Figure 1 As described, this is determined by a further circuit (readout circuit 12 ), whereby the voltage difference between reference electrode 7 and anode 3 can be determined.

[0075] The capacitor 28 prevents the reference electrode 7 from being short-circuited with the anode 3 via the resistor 22, the coil 26 and the connecting wire 11. In addition, the resistor 22 limits the current through the reference electrode 7.

[0076] Figure 3 A circuit 21 is shown, which is similar to Figure 2 The circuit shown in 20. Figure 3 In the upper part of the oscillating circuit 8, the oscillating circuit has in principle the Figure 2 The circuit 21 also has a reference electrode 7 and a (in some cases high-ohmic) resistor 22. However, it differs from Figure 2 , resistor 22 leads to point 31, which is provided for connection to cathode lead 10. Reference electrode 7 is connected to point 25. Figure 1 When the components shown in FIG. 1 are modified accordingly, the same may be done.

[0077] As described above, embodiments of the present invention enable a “contactless or wireless” readout or measurement of the half-cell potential of the reference electrode 7 or the voltage between the reference electrode 7 and one of the working electrodes. Therefore, no third terminal is required for the reference electrode 7, and therefore no additional (third) electrical connection through the housing 2 of the battery cell 1 is required.

[0078] As a basis Figure 2 A variation of the circuit is also possible in which a resistor is connected between point 25 and point 30 / anode 3 in addition to resistor 22 or instead of resistor 22. The same applies to Figure 3 A circuit in which the resistor 22 or an additional resistor can be arranged between the point 25 and the reference electrode 7.

[0079] As a basis Figure 2 and 3 In other variants of the circuit, the resistor 22 or an additional resistor can also be omitted (depending on the application).

[0080] A suitable resistance value for resistor 22 or an additional resistor results, for example, from the task that resistor 22 or an additional resistor is to perform. The task may include, in particular, limiting the charging current for reference electrode 7 and / or reducing leakage currents to be described. Depending on the application, the possible resistance values ​​may differ by several orders of magnitude.

[0081] As non-limiting examples, the following material pairs may be used for the working electrodes (anode / cathode):

[0082] Graphite / NMC (lithium-nickel-manganese-cobalt oxide);

[0083] Graphite and silicon / NCA (lithium-nickel-cobalt-alumina);

[0084] Graphite / LCO (lithium cobalt oxide).

[0085] Another advantage of the embodiments of the present invention is that Figure 4 To explain.

[0086] Figure 4 The diagram shows the half-cell potential of two materials as a function of the state of charge (SOC). The state of charge is plotted on the horizontal axis, which ranges from 0% to 100% state of charge. The half-cell potential is plotted on the vertical axis, more precisely in volts, relative to the lithium half-cell (V, relative to Li). It should be noted that the half-cell potential Figure 4 The curves 40 and 41 shown in should only provide a qualitative impression and should not be regarded as quantitatively accurate.

[0087] The half-cell potential of a graphite anode is shown by curve 41. The half-cell potential of the graphite anode decreases from a maximum value A at a state of charge of 0% to a significantly lower value at a state of charge of 100%.

[0088] The curve 40 shows the half-cell potential of the reference electrode 7. The half-cell potential of the reference electrode rises from a small value (0 volts or close to 0 volts) at a state of charge of 0% to a value B, which is reached at a state of charge D of about 15% to 20%. The curve 40 has a plateau between the state of charge D and a further state of charge E, which may be at about 80% to 90%. In this region, the half-cell potential of the curve 40 remains essentially constant. Above the state of charge E, the half-cell potential 40 continues to rise until a maximum value is reached at a state of charge of 100%.

[0089] In order to explain the embodiments of the present invention Figure 4 For the relationship between the potential curves of the individual half-cells, reference is again made to the above-mentioned US Pat. No. 8,586,222, in which the charging or recharging of the reference electrode is explained (the charging or recharging of the reference electrode is anyway familiar to a person skilled in the art).

[0090] It is now assumed that the half-cell potential (curve 40) of the reference electrode 7 has a value at a certain point in time that is at or near the maximum value (right end of the curve 40). Due to the leakage current flowing through the varactor diode 24 and / or the capacitor 28 connected in parallel, and chemical processes (which usually occur over a period of several days), the state of charge of the reference electrode changes towards 0%, that is, the half-cell potential of the reference electrode 7 slowly moves to the left on the curve 40. However, over a relatively large area, i.e., in the area of ​​the plateau (approximately between points D and E), the half-cell potential of the reference electrode 7 remains constant, so that over this area the half-cell potential of the reference electrode 7 can be used as an almost constant reference potential relative to the anode 3. In this area, the potential of the reference electrode 7 is greater than the potential of the anode 3, so that Figure 2 The varactor 24 in the circuit 20 is blocked. The varactor 24 thus acts like a capacitor, thereby providing a circuit 20 for determining a voltage difference between the reference electrode 7 and the anode 3, in particular.

[0091] If the state of charge of the reference electrode continues to decrease (that is, the state of charge moves to the area to the left of point D on the curve 40), the half-cell potential of the reference electrode 7 decreases. However, it never reaches a state of charge of 0%, more precisely for the following reason: in the case of point C, the half-cell potential curve 40 of the reference electrode 7 and the half-cell potential curve 41 of the anode 3 intersect. When the half-cell potential of the reference electrode 7 reaches point C (or reaches the area to the left of point C), the reference electrode 7 is at a lower potential than the anode 3. Therefore, the varactor diode 24 (see Figure 2 ) is turned on, so that the reference electrode 7 is “recharged”. By this recharging, the half-cell potential of the reference electrode 7 returns again to a point on the curve 40 located to the right of point E, and the process can be repeated.

[0092] During the recharging of the reference electrode 7, it is not available in order to provide a stable reference potential relative to the anode 3 (precisely because the reference electrode 7 is recharged by the anode 3). However, this is not to be regarded as a major disadvantage, since the function of the reference electrode 7 is available precisely during the charging of the battery cells and at higher states of charge of the battery cells (which can be important, for example, to avoid plating).

[0093] Figure 5 A flow chart with method steps of the method according to the invention is shown. After starting the method 50, the components described above are provided in step 51. This can be, for example, based on Figure 1 A component, wherein the component may have Figure 2 The circuit 20 or after appropriate modification has Figure 3 Circuit 21 or a circuit with similar functions.

[0094] Next, the resonance frequency of the oscillating circuit 8 is detected in step 52. The readout circuit 12 can be used to detect the resonance frequency of the oscillating circuit, if necessary in conjunction with a battery (cell) management system 13 or the like.

[0095] Next, in a further step 53, the voltage of the battery cell 1 is determined based on the detected resonance frequency. This can in turn be performed by the readout circuit 12, the battery (cell) management system 13 or the like. The method (step 54) ends with this. The determined voltage can then be used by the battery (cell) management system 13 for the purposes mentioned above.

[0096] As a variant or extension of the circuit, battery cell, assembly and method described above, it is possible to determine further measured variables wirelessly or contactlessly, that is to provide further measured variables at a point outside the battery cell housing 2, which relate to processes or states within the battery cell housing 2. For this purpose, for example Figure 2Circuit 20 or Figure 3 The circuit 21 can be modified as follows, that is, instead of the structural element 24 whose capacitance is dependent on the voltage applied to the structural element (in the example described above, the structural element is a varactor diode 24), a structural element whose capacitance is dependent on another measured variable is used. This alternative structural element can, for example, have a pressure probe, in the case of which the existing pressure is transmitted to one or both plates of the capacitor. By changing the pressure in the battery cell 1, the distance between the plates of the capacitor changes, thereby changing the capacitance of the capacitor. The change in capacitance will in turn cause a change in the resonant frequency of the (modified) oscillating circuit 8. The changed resonant frequency can then be read out as described above.

[0097] In another example, the structural element 24 can be replaced by a structural element whose capacitance is dependent on the temperature in the battery cell 1. Such a structural element can be provided, for example, so that a temperature change can cause a length change of a part of the component. The variable-length part can be coupled to the plates of a capacitor, so that the distance between the plates of the capacitor changes due to the temperature change. This change will in turn have an effect on the resonant frequency of the (modified) oscillating circuit 8, wherein the changed resonant frequency can be read out as described above.

[0098] In the variants described above, the circuit 20 or 21 requires in principle only the resonant circuit 8 , ie the reference electrode 7 , the resistor 22 and the connecting line 11 either to the anode 3 or to the cathode 5 can be omitted.

[0099] At least one exemplary embodiment has been described above, but it should be noted that there are numerous variants thereto. It should also be noted that the described exemplary embodiments constitute only non-limiting examples and are not intended to limit the scope, applicability or configuration of the apparatus and method described herein. More precisely, the above description provides a person skilled in the art with instructions for implementing at least one exemplary embodiment, wherein it is self-evident that the elements described in the exemplary embodiments may be modified in various ways with respect to the principle of action and arrangement, without departing from the technical solutions respectively determined in the present invention and their legal equivalents.

[0100] Reference numerals list

[0101] 1 battery cell

[0102] 2 Shell

[0103] 3 Anode

[0104] 4 Anode terminal

[0105] 5 cathode

[0106] 6 Cathode terminal

[0107] 7 Reference electrode

[0108] 8 Oscillating circuit

[0109] 9 Anode wire

[0110] 10 cathode wire

[0111] 11. Connect the wires

[0112] 12 Readout circuit

[0113] 13Battery (monomer) management system

[0114] Circuit 20, 21

[0115] 22 resistors

[0116] 23 (contact) points

[0117] 24 Structural elements / varicap diodes

[0118] 25 (contact) points

[0119] 26 coils

[0120] 28 Capacitors

[0121] 30, 31 (contact) points

[0122] 40 Reference electrode half-cell potential curve

[0123] 41 Half-cell potential curve of (graphite) anode

[0124] 50-54 Method steps

[0125] 100 components

[0126] A, B potential level

[0127] C intersection

[0128] D. E state of charge

Claims

1. An assembly (100) for determining a first voltage present in a battery cell (1), the assembly comprising a battery cell (1), the battery cell comprising: A first battery cell electrode and a second battery cell electrode, wherein the first battery cell electrode and the second battery cell electrode are located in a housing (2) of the battery cell (1); as well as A circuit (20, 21), the circuit also being located in the housing (2) of the battery cell (1), the circuit being capable of determining a first voltage present in the battery cell (1), the circuit comprising: - an oscillating circuit (8), the oscillating circuit having a coil (26) and a component (24), the capacitance of the component being dependent on a voltage applied to the component (24), the resonant frequency of the oscillating circuit (8) being dependent on the voltage applied to the component (24); and - a reference electrode (7), The circuit (20, 21) is configured to be arranged in the housing (2) of the battery cell (1) such that a first voltage existing between the battery cell electrodes (3, 5) and the reference electrode (7) is at least partially applied to the component (24), and the resulting resonant frequency of the oscillating circuit (8) can be detected outside the housing (2) via the magnetic field of the coil (26), the resonant frequency of the oscillating circuit can be determined from the detected magnetic field, and thus the voltage applied to the component (24) can be determined based on the resonant frequency of the oscillating circuit (8), wherein the oscillating circuit (8) is connected to the first battery cell electrode and the reference electrode (7) such that a first electrical contact of the component (24) is electrically connected to the first battery cell electrode, and a second electrical contact of the component (24) is electrically connected to the reference electrode (7), The component further comprises a further circuit (12), which is at least partially arranged outside the housing (2) of the battery cell (1) and is configured to detect the resonant frequency of the oscillating circuit (8) via the magnetic field of the coil (26), thereby ultimately being able to read out a first voltage and thus being able to provide information about the charge state of the battery cell outside the battery cell.

2. The assembly (100) according to claim 1, wherein The component (24) has a diode.

3. The assembly (100) according to claim 1 or 2, wherein: The resonant circuit (8) has a capacitor (28) which is connected in series with the component (24).

4. The assembly (100) according to claim 1 or 2, wherein: The half-cell potential (40) of the material of the reference electrode (7) has a plateau.

5. The assembly (100) according to claim 1 or 2, wherein: The reference electrode (7) comprises one or more of the following materials: -Lithium iron phosphate; - lithium titanate; - lithium manganese phosphate; -Lithium-gold alloy.

6. The assembly (100) according to claim 2, wherein The diode is a varactor diode.

7. The assembly according to claim 1 or 2, wherein: The resistor (22) is electrically connected between the oscillating circuit (8) and the first battery cell electrode or between the oscillating circuit (8) and the reference electrode (7).

8. The assembly (100) according to claim 1 or 2, wherein: a first battery cell contact portion accessible from outside the battery cell (1) is electrically connected to the first battery cell electrode via a first electrical connection portion, the first electrical connection portion being led through the housing (2) of the battery cell (1); a second battery cell contact accessible from outside the battery cell (1) is electrically connected to the second battery cell electrode via a second electrical connection, the second electrical connection being led through the housing (2) of the battery cell (1); and No further electrical connections are passed through the housing (2) of the battery cell (1).

9. The assembly (100) according to claim 1 or 2, wherein: The electrical circuit (20, 21) and the further electrical circuit (12) are electrically insulated from one another.

10. A battery comprising: Two or more assemblies (100) according to any one of claims 1 to 9.

11. A method for determining a first voltage present in a battery cell (1), the method comprising: - providing an assembly (100) according to any one of claims 1 to 9; - detecting the resonant frequency of the oscillating circuit (8) by means of the further circuit (12) via the magnetic field of the coil (26); and - determining a first voltage present in the battery cell (1) based on the detected resonance frequency of the oscillating circuit (8).

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