Method for monitoring a battery, a device for this purpose, a battery and a motor vehicle with such

Abstract

The invention relates to a method for monitoring a battery (110). The method comprises reading in (10) information (100). This information (100) preferably provides an indication of an available energy load and is obtained from a sensor (130). The sensor (130) is integrated into a battery cell stack (120). A pressure sensor is preferably used as the sensor (130). The method comprises evaluating (20) the read-in information (100). Furthermore, the method comprises determining (30) a mechanical expansion (140). This is based on the evaluated read-in information (100). Furthermore, the invention relates to a corresponding battery (110), a battery monitoring device (300) and a motor vehicle (400).

Description

[0001] The present invention relates to a method for monitoring a battery, a device for this purpose, a battery and a motor vehicle with such a battery.

[0002] Knowledge of stack swelling / jellyroll swelling in a battery is extremely helpful in cell design and determining the operating strategy (e.g., fast charging, voltage limit, etc.). The term "battery swelling," or simply swelling, refers to the physical enlargement or expansion of a battery during the charging and discharging process. Battery swelling is common in lithium-ion batteries, but can also occur in other battery types.

[0003] However, the metallic cell casing of a battery makes it difficult to directly detect mechanical expansion or jellyroll.

[0004] Thus, the mechanical expansion of cell stacks in prismatic cells or a cylindrical electrode coil (jellyroll) in cylindrical cells cannot currently be directly detected.

[0005] Therefore, computed tomography and / or a dilatometer are often used to indirectly measure swelling. However, these are limited to 2D planes.

[0006] The aim of the invention is to propose a possibility which avoids or at least reduces at least some of the disadvantages known in the prior art.

[0007] The object is achieved according to the invention by means of a method according to the main claim and by means of devices according to the independent claims.

[0008] The subject matter of the main claim relates to a method for monitoring a battery. The method comprises reading information. This information preferably provides an indication of available energy and is obtained from a sensor. The sensor is integrated into a battery cell stack. A pressure sensor is preferably used as the sensor.

[0009] The procedure involves evaluating the information read in.

[0010] The method further comprises determining a mechanical extension. Preferably, a mechanical force is determined as a mechanical extension. This is based on the evaluated, read-in information.

[0011] The process steps can be carried out automatically.

[0012] A battery, as defined by the invention, refers to an electrochemical energy source that can be electrically charged and deliver its stored electrical energy to a connected electrical device as needed. In particular, this can refer to an electrochemical energy source based on lithium-ion cells.

[0013] Information within the meaning of the invention means measurement data or measurement signals from a sensor which it can provide.

[0014] An energy load, as defined by the invention, refers to the total electrical energy or electrical power available and deliverable in the battery. It can also refer to the maximum electrical energy or electrical power available from the battery by a consumer connected to the battery.

[0015] A battery cell stack within the meaning of the invention refers to a stack of battery cells. This can preferably be a lithium-ion cell stack.

[0016] A sensor within the meaning of the invention refers to an electrical component or part that can measure at least one parameter and output information that allows a conclusion to be drawn about the measured value. The sensor can preferably be a pressure sensor. Even more preferably, the sensor can be a piezo sensor for measuring pressure. The sensor can preferably output an electrical signal whose value represents the measured value.

[0017] Mechanical expansion within the meaning of the invention refers to a physical expansion of at least one battery cell. It can also refer to the physical expansion of the battery itself. Furthermore, it can also refer to the physical expansion of the battery casing. Furthermore, it can also refer to an internal pressure of the battery or a battery cell. Determining the mechanical expansion, preferably a mechanical force, of the battery cell stack can refer to the mechanical force acting on the battery cell stack.

[0018] The teaching of the invention achieves the advantage of providing a method for the rapid and accurate identification of mechanical expansion. This has the advantage that the swelling of a battery cell can be directly measured.

[0019] The fact that the sensor is integrated into the battery also allows for continuous monitoring of the swelling and thus the functionality of a battery.

[0020] Another advantage is that harmful fast-charging profiles can be identified. Furthermore, the cell's fast-charging capability can be better utilized, allowing the cell to be charged more quickly without exposing it to the risk of damage from overcharging or incorrect charging. This can improve the battery's durability and service life. Another advantage is that it enables battery charge and / or aging detection.

[0021] The subject matter of a subordinate claim relates to a battery. The battery comprises a battery cell stack. The battery also comprises a sensor integrated into the battery cell stack.

[0022] The integrated sensor is designed to output information. This information can be used to determine the mechanical expansion of the battery cell stack.

[0023] The teaching according to the invention achieves the advantage that swelling of a battery cell can be measured directly.

[0024] The subject matter of a further independent claim relates to a battery monitoring device comprising: A reading device for reading information from a sensor integrated into a battery cell stack of a battery. The battery monitoring device comprises an evaluation means for evaluating the read-in information. The battery monitoring device also includes a detection device for determining mechanical expansion of the battery cell stack. This detection is based on the evaluated, read-in information. The battery monitoring device is further configured to carry out a method according to the invention. Because the sensor is integrated into the battery, it allows for continuous monitoring of the swelling and thus monitoring of the functionality of a battery.

[0025] The subject matter of a further independent claim relates to a motor vehicle comprising a battery according to the invention and a battery monitoring device according to the invention.

[0026] The teaching of the invention achieves the advantage of providing a motor vehicle in which the functionality of a battery integrated into the vehicle can be continuously and directly monitored. This can, among other things, prevent battery fires.

[0027] The subject matter of a further independent claim relates to a computer program with a program code which, when executed on a programmable processor, causes a method according to the invention to be carried out.

[0028] The teaching of the invention offers the advantage that the process can be efficiently automated, thus enabling further cost savings.

[0029] Before describing embodiments of the invention in more detail below, it should first be noted that the invention is not limited to the described components or the described method steps. Furthermore, the terminology used does not represent a limitation, but is merely exemplary. Where the singular is used in the description and claims, the plural is included unless the context explicitly excludes this. Any method steps can be performed automatically unless the context explicitly excludes this.

[0030] Furthermore, process features can be converted into device features and vice versa.

[0031] Further exemplary embodiments of the method according to the invention are explained below.

[0032] According to a first exemplary embodiment, the method further comprises reading in additional information. This additional information is detected by another sensor. This sensor surrounds the battery cell stack. This additional sensor preferably provides further indication of the available energy load.

[0033] The method further comprises evaluating the additional information read in.

[0034] Furthermore, the determination of the mechanical expansion of the battery cell stack is also based on the evaluated additional information read in.

[0035] The additional sensor can, for example, be a sensor that can measure another physical property of a battery cell or a battery.

[0036] Thus, the additional sensor can be a different type of sensor than the sensor. For example, the additional sensor can be a force sensor. Preferably, the additional sensor is a load cell.

[0037] This design has the advantage that the monitoring of swelling can be more accurate and thus the monitoring of the battery's functionality can be improved.

[0038] According to another exemplary embodiment, the method further comprises reading in a third piece of information. This information, which preferably provides an even further indication of the available energy load, is detected by a third sensor integrated into the battery cell stack.

[0039] It also includes the evaluation of the third information read in.

[0040] The mechanical expansion of the battery cell stack is also determined on the basis of the evaluated third information read in.

[0041] The third sensor can, for example, be a sensor that can measure a different physical property of a battery cell or a battery than the sensor and / or other sensors.

[0042] Thus, the third sensor can be a different type of sensor than the sensor and / or other sensor. For example, the third sensor can be a temperature sensor. For example, this sensor can be implemented as a so-called NTC sensor (negative temperature coefficient). For example, this sensor can be integrated as a so-called digital temperature sensor. Furthermore, the third sensor can be an impedance sensor. This sensor can, for example, be implemented as a so-called EIS sensor on a chip.

[0043] This design has the advantage that the monitoring of swelling can be even more accurate and thus the monitoring of the functionality of the battery can be further improved.

[0044] According to another exemplary embodiment, the method further comprises reading in a fourth piece of information. This information is detected by a fourth sensor. This sensor is integrated between the battery cell stack and another battery cell stack. This information preferably provides a fourth indication of the available energy load.

[0045] The procedure also includes evaluating the fourth piece of information read in.

[0046] The determination of the mechanical expansion of the battery cell stack is additionally carried out based on the evaluated, read-in fourth information.

[0047] Thus, the fourth sensor can be a different type of sensor than the sensor, the further sensor, and / or the third sensor. For example, the fourth sensor can be a reference electrode. For example, this sensor can be implemented as a so-called LTO reference electrode sensor. For example, this can be a parylene-coated aluminum wire or aluminum flag. This can be inserted between two battery cells by inserting an additional separator. Furthermore, the fourth sensor can consist of a gold wire or even lithium titanium oxide (LTO) or similar materials. This can be inserted between two battery cells and / or between two battery cell stacks.

[0048] This allows the anode potential to be measured, which allows the charging profile to be optimized over the cell's lifetime.

[0049] This design has the advantage that the monitoring of swelling can be even more accurate and thus the monitoring of the functionality of the battery can be further improved.

[0050] Each of the four sensors can be used as a sensor, a second sensor, a third sensor, or a fourth sensor. This means that instead of the sensor, the additional sensor, the third sensor, or the fourth sensor can also be used. The four sensors, or their sensor types, can be interchanged as desired within the embodiments of the invention.

[0051] Very good results are also achieved using a pressure sensor, such as a gas pressure sensor, as the sensor and a load cell as the additional sensor. A load cell can be a force transducer, i.e., a sensor that measures the applied force. Other common terms for 'load cell' are 'force ring,' 'measuring washer,' or 'force sensor.' There are various ways to measure forces. One widely used option is strain gauge technology, which requires an elastic measuring element in the load cell to record the applied force. Load cells based on the piezoelectric measuring principle contain piezoelectric measuring elements that generate a charge under load (pressure). The piezoelectric element can function simultaneously as a sensor element and as a transmission element for the applied force.A downstream charge amplifier converts this transfer element into an analyzable process signal. When integrating the sensor, care should be taken to ensure that the sensor's sealing is at least 4 bar, preferably above 6 bar, and that the operating temperature is, for example, between -35°C and +70°C, preferably -45°C and +85°C. Integration methods could include epoxy bonding, riveting, welding, or similar methods. The integration materials should, if possible, not react with the electrolyte.

[0052] According to another exemplary embodiment, the method further comprises determining cell swelling of the battery cell stack. This is done based on the determined mechanical expansion.

[0053] This design has the advantage that the monitoring of the battery's functionality can be further improved.

[0054] According to another exemplary embodiment, the method further comprises determining battery aging. This is done based on the determined mechanical expansion and / or cell swelling.

[0055] This design has the advantage of allowing timely response to a critical battery malfunction, allowing the battery to be replaced in a timely manner. This allows the battery to be replaced at specific times. Consequently, it no longer needs to be replaced too early or too late based on assumptions and average usage experience according to a standard cycle. This can save costs.

[0056] The invention will be explained in more detail below with reference to the figures, in which: Fig. 1 a schematic representation of a proposed method according to an exemplary embodiment of the invention; Fig. 2 a schematic representation of a proposed battery according to a further exemplary embodiment of the invention; Fig. 3 is a schematic representation of a proposed battery monitoring device according to a further exemplary embodiment of the invention; Fig. 4 is a schematic representation of a proposed motor vehicle according to a further exemplary embodiment of the invention; and Fig. 5 schematic representations of measurement results regarding the internal cell pressure and cell swelling of a battery according to the invention.

[0057] Fig. 1 shows a schematic representation of a proposed method according to an exemplary embodiment of the invention.

[0058] This shows Fig. 1 shows a schematic representation of a method for monitoring a battery 110. The method comprises reading 10 information 100. This information 100 preferably provides an indication of an available energy load and is obtained from a sensor 130. The sensor 130 is integrated into a battery cell stack 120. A pressure sensor is preferably used as the sensor 130.

[0059] The method comprises evaluating 20 the read information 100.

[0060] The method further comprises determining a mechanical extension 140. Preferably, the mechanical extension 140 comprises a mechanical force. This is based on the evaluated, read-in information 100.

[0061] Fig. 2 shows a schematic representation of a proposed battery 110 according to another exemplary embodiment of the invention.

[0062] How Fig. 2, the battery 110 has a battery cell stack 120. The battery 110 also has a sensor 130 integrated into the battery cell stack 120.

[0063] The integrated sensor 130 is configured to output information 100. This information 100 is suitable for allowing a conclusion about a mechanical expansion 140 of the battery cell stack 120.

[0064] Fig. 3 shows a schematic representation of a proposed battery monitoring device 300 according to another exemplary embodiment of the invention.

[0065] How Fig. 3, the battery monitoring device 300 has a reading means 220 for reading 10 information 100 from a sensor 130 integrated into a battery cell stack 120 of a battery 110.

[0066] The battery monitoring device 300 comprises an evaluation means 230 for evaluating the read-in information 100.

[0067] In addition, the battery monitoring device 300 includes a determination means 240 for determining 30 a mechanical expansion 140 of the battery cell stack 120. This determination 30 is based on the evaluated read-in information 100.

[0068] The battery monitoring device 300 is further configured to carry out a method according to the invention.

[0069] Fig. 4 shows a schematic representation of a proposed motor vehicle according to a further exemplary embodiment of the invention.

[0070] How Fig. 4, motor vehicle 400 has a battery 110 according to the invention and a battery monitoring device 300 according to the invention.

[0071] Fig. 5 shows schematic representations of measurement results regarding the internal cell pressure and cell swelling of a battery according to the invention.

[0072] Fig. Figure 5a shows the measured cell capacity and swelling force over time (in days).

[0073] Fig. Figure 5b shows the battery voltage and the internal cell pressure of the battery over the SOC (in percent). The State of Charge (SoC) represents a parameter for the charge level of a battery. It thus describes the remaining available capacity of a battery relative to its nominal value and is expressed as a percentage.

[0074] Fig. Figure 5c shows the measured internal cell pressure of a battery according to the invention over time (in days).

[0075] The inventive concept can be summarized as follows: A method, a battery, a battery monitoring device, and a motor vehicle are provided, which make it possible to perform direct swelling measurements on batteries or battery cell stacks. This can improve their charging capacity. Furthermore, the aging of the battery or individual battery cell stacks can be monitored. Furthermore, critical battery behavior can be anticipated, for example, by disconnecting the battery upon detection of a rapidly rising internal cell pressure, thus removing it from the load, and / or cooling the battery more effectively.

[0076] The stack volume / JR volume changes over the cell charge state and the battery life due to various effects: - Short-term effect per cycle: Electrode volume change via lithiation degree. - Long-term effect over lifetime: pressure increase due to layer growth (SEI / plating) on ​​anode, gas release from electrodes and electrolyte. - Other influencing factors such as cell temperature.

[0077] To monitor and manage these effects, battery cells, battery cell stacks, or batteries with integrated pressure sensors and / or load cells are provided. Examples of these cells include two prismatic cells with graphite and graphite / SiOx anodes.

[0078] Using the ideal gas law, the volume changes of electrodes due to pressure changes of ideal gases can be calculated. For simplicity, it can be assumed that no additional gas formation occurs per cycle.

[0079] This allows the gas or gas pressure to be determined at a defined state of charge. This method is suitable for both prismatic cells and pouch-sized cells. The sensor(s) and the integration concept can be optimized for a specific format. List of reference symbols 10 Reading in information 20 Evaluating the information 30 Determining mechanical expansion of the battery cell stack 40 Reading in further information 50 Evaluating further information 60 Reading in a third piece of information 70 Evaluating the third information 80 Reading in a fourth piece of information 90 Evaluating the fourth information 92 Determining cell swelling 94 Determining battery aging 100 Information 110 Battery 120 battery cell stack 120' additional battery cell stack 130 sensors 140 mechanical expansion (of the battery cell stack) 150 Further information 160 Additional sensor 170 Third Information 180 Third Sensor 190 Fourth Information 200 Fourth Sensor 210 Cell swelling 220 reading devices for reading the information 230 evaluation tools for evaluating the information 240 Instruments for determining mechanical expansion 300 Battery monitoring device 400 motor vehicles

Claims

[1] A method for monitoring a battery (110), the method comprising: - reading (10) information (100), preferably information that provides an indication of an available energy load, from a sensor (130), preferably a pressure sensor, integrated into a battery cell stack (120) of the battery (110); - evaluating (20) the read information (100); and - Determining (30) a mechanical expansion (140), preferably a mechanical force, of the battery cell stack (120) based on the evaluated read-in information (100). [2] The method according to claim 1, the method further comprising: - reading (40) further information (150), preferably information that provides a further indication of the available energy load, from a further sensor (160) surrounding the battery cell stack (120); and - evaluating (50) the read-in further information (150); wherein the determination (30) of the mechanical expansion (140) of the battery cell stack (120) is additionally carried out based on the evaluated read-in further information (150). [3] The method according to claim 1 or 2, the method further comprising: - reading (60) a third piece of information (170), preferably information that provides a further indication of the available energy load, from a third sensor (180) integrated into the battery cell stack; and - evaluating (70) the read-in third information (170); wherein the determination (30) of the mechanical expansion (140) of the battery cell stack (120) is additionally carried out based on the evaluated read-in third information (170). [4] The method according to any one of the preceding claims, the method further comprising: - reading (80) a fourth piece of information (190), preferably information that provides a fourth indication of the available energy load, from a fourth sensor (200) integrated between the battery cell stack (120) and a further battery cell stack (120'); and - evaluating (90) the read-in fourth information (190); wherein the determination (30) of the mechanical expansion (140) of the battery cell stack (120) is additionally carried out based on the evaluated read-in fourth information (190). [5] The method according to any one of the preceding claims, the method further comprising: - Determining (92) a cell swelling (210) of the battery cell stack (120) based on the determined mechanical expansion (140). [6] The method according to any one of the preceding claims, the method further comprising: - Determining (94) an aging of the battery (110) based on the determined mechanical expansion (140) and / or the determined cell swelling (210). [7] A battery (110) comprising: - a battery cell stack (120); and - a sensor (130) integrated into the battery cell stack (120); wherein the integrated sensor (130) is configured to output information (100) suitable for allowing a conclusion to be drawn about a mechanical expansion (140) of the battery cell stack (120). [8] A battery monitoring device (300) comprising: - A reading means (220) for reading (10) information (100) from a sensor (130) integrated into a battery cell stack (120) of a battery (110); - an evaluation means (230) for evaluating (20) the read-in information (100); and - a determination means (240) for determining (30) a mechanical expansion (140) of the battery cell stack (120) based on the evaluated read-in information (100); wherein the battery monitoring device (300) is configured to carry out a method according to any one of the preceding claims 1 to 6. [9] A motor vehicle (400), comprising: a battery (110) according to claim 7; and a battery monitoring device (300) according to claim 8. [10] A computer program comprising program code which, when executed on a programmable processor, causes a method according to any one of claims 1 to 6 to be carried out.

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