Method of installing an ultrasonic sensor on a battery cell

Abstract

The application provides a method for installing ultrasonic sensors on a battery monomer, wherein the battery monomer comprises a shell, the shell comprises a top wall, a bottom wall and a side wall surrounding a closed space with the top wall and the bottom wall, the method for installing ultrasonic sensors on the battery monomer comprises the following steps: pasting a first ultrasonic sensor on a first pasting area of the side wall, pasting a second ultrasonic sensor on a second pasting area of the side wall opposite to the first pasting area; and welding a first positive electrode lead wire with the first ultrasonic sensor, bonding a first negative electrode lead wire with the side wall, welding a second positive electrode lead wire with the second ultrasonic sensor, and bonding a second negative electrode lead wire with the side wall. The technical scheme of the embodiment of the application can improve the accuracy of quality detection of the battery monomer by using the first ultrasonic sensor and the second ultrasonic sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery manufacturing, in particular to a method for installing an ultrasonic sensor on a battery cell. BACKGROUND

[0002] A battery cell is the smallest unit that provides an energy source in a battery. In the process of manufacturing a battery, quality detection of the battery cell is crucial. In the related art, an ultrasonic sensor is generally installed on the surface of the battery cell to perform non-destructive quality detection of the battery cell by using the piezoelectric effect of the ultrasonic sensor.

[0003] Whether the installation of the ultrasonic sensor on the battery cell is qualified is a key to the accuracy of quality detection of the battery cell. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present application is to provide a method for installing an ultrasonic sensor on a battery cell to improve the accuracy of quality detection of the battery cell by using the ultrasonic sensor.

[0005] The present application provides a method for installing an ultrasonic sensor on a battery cell, including: the battery cell including a shell, the shell including a top wall, a bottom wall, and a side wall enclosing a closed space with the top wall and the bottom wall, the method including: pasting a first ultrasonic sensor at a first pasting area of the side wall, pasting a second ultrasonic sensor at a second pasting area of the side wall opposite the first pasting area; and welding a first positive electrode lead wire with the first ultrasonic sensor, adhering a first negative electrode lead wire with the side wall, welding a second positive electrode lead wire with the second ultrasonic sensor, and adhering a second negative electrode lead wire with the side wall.

[0006] The installation method provided by the embodiments of the present application can be used not only for installation qualification evaluation but also for test scheme verification, so that the optimal installation scheme of the ultrasonic sensor on the battery cell can be determined to achieve the optimal installation of the ultrasonic sensor on the battery cell. Therefore, the embodiments of the present application can improve the accuracy of quality detection of the battery cell by using the ultrasonic sensor.

[0007] In some embodiments, the side wall includes opposite first and second side surfaces, the first pasting area is located at the first side surface, the second pasting area is located at the second side surface, the first negative electrode lead wire is adhered to the first side surface, and the second negative electrode lead wire is adhered to the second side surface.

[0008] The embodiments of the present application can be applied to battery cells of various shapes, have a wide range of applications, and are particularly suitable for battery cells of regular shapes such as a substantially flat body, a cuboid, or a cube.

[0009] In some embodiments, the method further includes: obtaining, with the first ultrasonic sensor as the excitation side and the second ultrasonic sensor as the receiving side, a forward excitation sensing signal output by the second ultrasonic sensor; obtaining, with the second ultrasonic sensor as the excitation side and the first ultrasonic sensor as the receiving side, a reverse excitation sensing signal output by the first ultrasonic sensor; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the forward excitation sensing signal and the reverse excitation sensing signal.

[0010] The installation of the two ultrasonic sensors on the battery cell can be evaluated, analyzed or tested based on the sensing signals output by the two ultrasonic sensors from the receiving side respectively in forward excitation and reverse excitation, so as to improve the accuracy of quality detection of the battery cell by the ultrasonic sensor.

[0011] In some embodiments, the method further includes: obtaining, with the first ultrasonic sensor as the excitation side and the second ultrasonic sensor as the receiving side, a forward excitation sensing signal output by the second ultrasonic sensor, including: providing a function generator, an amplifier and an oscilloscope, and connecting the function generator and the amplifier; connecting the amplifier with the first positive lead and the first negative lead, and connecting the oscilloscope with the second positive lead and the second negative lead; and collecting the forward excitation sensing signal output by the oscilloscope; obtaining, with the second ultrasonic sensor as the excitation side and the first ultrasonic sensor as the receiving side, a reverse excitation sensing signal output by the first ultrasonic sensor, including: providing a function generator, an amplifier and an oscilloscope, and connecting the function generator and the amplifier; connecting the amplifier with the second positive lead and the second negative lead, and connecting the oscilloscope with the first positive lead and the first negative lead; and collecting the reverse excitation sensing signal output by the oscilloscope.

[0012] In some embodiments, the evaluation of the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the forward excitation sensing signal and the reverse excitation sensing signal includes: determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell is qualified in response to determining that the feature difference of the forward excitation sensing signal and the reverse excitation sensing signal is within an error range; and determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell is unqualified in response to determining that the feature difference of the forward excitation sensing signal and the reverse excitation sensing signal exceeds the error range.

[0013] The embodiment evaluates the installation of the two ultrasonic sensors on the battery cell based on the sensing signals output by the two ultrasonic sensors from the receiving side respectively in forward excitation and reverse excitation.

[0014] In some embodiments, the method further comprises: providing a capacitance measuring instrument; measuring, using the capacitance measuring instrument, a first capacitance between the first positive electrode lead and the first negative electrode lead, and a second capacitance between the second positive electrode lead and the second negative electrode lead; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the first capacitance and the second capacitance.

[0015] In some embodiments, the method further comprises: providing a capacitance measuring instrument; measuring, using the capacitance measuring instrument, a first capacitance between the first positive electrode lead and the first negative electrode lead, and a second capacitance between the second positive electrode lead and the second negative electrode lead; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the first capacitance and the second capacitance.

[0016] In some embodiments, the method further comprises: providing a capacitance measuring instrument; measuring, using the capacitance measuring instrument, a first capacitance between the first positive electrode lead and the first negative electrode lead, and a second capacitance between the second positive electrode lead and the second negative electrode lead; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the first capacitance and the second capacitance.

[0017] In some embodiments, the method further comprises: providing a capacitance measuring instrument; measuring, using the capacitance measuring instrument, a first capacitance between the first positive electrode lead and the first negative electrode lead, and a second capacitance between the second positive electrode lead and the second negative electrode lead; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the first capacitance and the second capacitance.

[0018] In some embodiments, the method further comprises: providing a capacitance measuring instrument; measuring, using the capacitance measuring instrument, a first capacitance between the first positive electrode lead and the first negative electrode lead, and a second capacitance between the second positive electrode lead and the second negative electrode lead; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the first capacitance and the second capacitance.

[0019] In some embodiments, the method further comprises, before pasting the first ultrasonic sensor and the second ultrasonic sensor, determining a test scheme for installing the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on a plurality of sensitive factors, wherein the plurality of sensitive factors comprises at least one of: positions of the first pasting area and the second pasting area on the side wall, polishing conditions of the first pasting area and the second pasting area, glue area proportions of the first pasting area and the second pasting area, welding point specifications on the first ultrasonic sensor and the second ultrasonic sensor, and an ambient temperature.

[0020] This embodiment provides a plurality of consideration factors for designing a test scheme. Considering these sensitive factors when designing a test scheme and using the aforementioned installation method can help find an optimal installation scheme for the ultrasonic sensors on the battery cell.

[0021] In some embodiments, welding the first positive electrode lead to the first ultrasonic sensor comprises welding the first positive electrode lead to a center position of a surface of the first ultrasonic sensor, and welding the second positive electrode lead to the second ultrasonic sensor comprises welding the second positive electrode lead to a center position of a surface of the second ultrasonic sensor. In this way, reliable installation of the leads to the two ultrasonic sensors can be achieved, and the two ultrasonic sensors can be made to have a relatively consistent installation capacitance after installation.

[0022] In some embodiments, the method further comprises polishing the first pasting area and the second pasting area before pasting the first ultrasonic sensor and the second ultrasonic sensor. In this way, the roughness of the pasting areas can be reduced, thereby helping to reduce attenuation of the ultrasonic signals.

[0023] In some embodiments, the method further comprises cleaning the first pasting area and the second pasting area before pasting the first ultrasonic sensor and the second ultrasonic sensor. In this way, foreign matter or dirt can be avoided from being attached, thereby helping to reduce attenuation of the ultrasonic signals and reduce interference with the ultrasonic signals.

[0024] In some embodiments, the method further comprises, before pasting the first ultrasonic sensor and the second ultrasonic sensor, measuring an intrinsic capacitance of the first ultrasonic sensor and an intrinsic capacitance of the second ultrasonic sensor, and in response to determining that the intrinsic capacitance of at least one of the first ultrasonic sensor and the second ultrasonic sensor is out of a capacitance error range, determining that the at least one of the first ultrasonic sensor and the second ultrasonic sensor is unqualified and replacing the at least one of the first ultrasonic sensor and the second ultrasonic sensor.

[0025] According to this embodiment, whether an ultrasonic sensor has been damaged or a performance parameter thereof has deviated can be determined based on measurement of an intrinsic capacitance thereof before pasting the ultrasonic sensor, thereby avoiding affecting the accuracy of detection after installation due to unqualified ultrasonic sensors, and reducing costs of human and material resources.

[0026] The above description is merely a summary of the application technical solutions, in order to more clearly understand the technical means of the application, and can be implemented according to the content of the specification, and in order to make the above and other purposes, features and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0027] In the drawings, like reference numerals refer to same or similar components throughout the several views, unless otherwise indicated. These drawings are not necessarily to scale, and the emphasis is instead placed upon the principles of the application. It is to be expressly understood that these drawings are only meant to depict some embodiments of the application, and should not be viewed as limiting the scope thereof.

[0028] Figure 1 Split structure schematic diagram of battery cell for some embodiments of the application;

[0029] Figure 2 Schematic diagram of mounting ultrasonic sensor on battery cell for some embodiments of the application;

[0030] Figure 3 Flowchart schematic diagram of method of mounting ultrasonic sensor on battery cell for some embodiments of the application;

[0031] Figure 4 Flowchart schematic diagram of method of mounting ultrasonic sensor on battery cell for some embodiments of the application;

[0032] Figure 5A Schematic diagram of taking first ultrasonic sensor as excitation side for some embodiments of the application;

[0033] Figure 5B Schematic diagram of taking second ultrasonic sensor as excitation side for some embodiments of the application;

[0034] Figure 6A Simulation comparison diagram of sensing signals obtained under different pasting positions for some embodiments of the application;

[0035] Figure 6B Simulation comparison diagram of sensing signals obtained under different glue coating area ratios for some embodiments of the application;

[0036] Figure 7A 、 Figure 7B Simulation comparison diagram of forward excitation sensing signals and reverse excitation sensing signals obtained from comparative test adopted according to some embodiments of the application;

[0037] Figure 8 Flowchart schematic diagram of method of mounting ultrasonic sensor on battery cell for some embodiments of the application.

[0038] Reference Signs List:

[0039] 20 - battery cell

[0040] 22 - housing

[0041] 23 - battery cell assembly

[0042] 221 - top wall

[0043] 222 - bottom wall

[0044] 223 - side wall

[0045] 21a - electrode terminal

[0046] 2231 - first side surface

[0047] 2232 - second side surface

[0048] 23a - tab

[0049] 30 - function generator

[0050] 40 - amplifier

[0051] 50 - oscilloscope

[0052] 61 - first ultrasonic sensor

[0053] 62 - second ultrasonic sensor

[0054] 711 - first positive electrode lead wire

[0055] 712 - first negative electrode lead wire

[0056] 721 - second positive electrode lead wire

[0057] 722 - second negative electrode lead wire DETAILED DESCRIPTION

[0058] The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0060] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly specified and limited.

[0061] Reference herein to "embodiments" means that the particular features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily a separate or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0062] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0063] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0064] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0065] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0066] Ultrasound is a mechanical wave with a vibration frequency higher than 20 kHz, which has the characteristics of high frequency, short wavelength and good directivity. The penetration of ultrasound to liquid and solid is very large, and it will produce significant reflection when encountering impurities or interface, thus forming a reflected echo. The ultrasonic sensor is a reversible piezoelectric sensor, which can convert the received electrical signal into mechanical oscillation to generate ultrasonic waves, and also can receive ultrasonic waves and convert them into electrical signals for output.

[0067] In the related art, the excitation side ultrasonic sensor (converts the received electrical signal into mechanical oscillation to generate ultrasonic waves) and the receiving side ultrasonic sensor (receives ultrasonic waves and converts them into electrical signals for output) are attached to a specific position on the surface of the battery monomer. Based on the ultrasonic piezoelectric principle, the wave shape characteristics of the electrical signal output by the receiving side ultrasonic sensor are used to detect defects inside the battery monomer, such as poor electrolyte infiltration, lithium precipitation, and active material shedding of the electrode sheet.

[0068] The inventors of the present application understand that whether the installation of the excitation side ultrasonic sensor and the receiving side ultrasonic sensor on the battery monomer is qualified is crucial to the accuracy of quality detection.

[0069] Based on this, the inventors have conducted in-depth research and provided a method for installing ultrasonic sensors on a battery monomer, in order to achieve the optimal installation of ultrasonic sensors on the battery monomer and improve the accuracy of quality detection of the battery monomer using ultrasonic sensors.

[0070] In the embodiments of the present application, one ultrasonic sensor is pasted on each of the symmetric positions (i.e., opposite positions) of the side walls of the shell of the battery monomer. In this way, the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer can be evaluated based on the difference (which should be consistent in theory, and in practice, it is acceptable as long as it is within a reasonable error range) between the sensing signals output by the two ultrasonic sensors in forward excitation (with the first ultrasonic sensor as the excitation side and the second ultrasonic sensor as the receiving side) and reverse excitation (with the second ultrasonic sensor as the excitation side and the first ultrasonic sensor as the receiving side), or based on the difference (which should be consistent in theory, and in practice, it is acceptable as long as it is within a reasonable error range) between the installation capacitances of the two ultrasonic sensors.

[0071] The installation method provided in the embodiments of the present application can not only be used for installation qualification evaluation, but also can be used for test scheme verification, so as to determine the optimal installation scheme of the ultrasonic sensor on the battery monomer, thereby achieving the optimal installation of the ultrasonic sensor on the battery monomer. Therefore, the embodiments of the present application can improve the accuracy of quality detection of the battery monomer using ultrasonic sensors.

[0072] The main structure of the battery includes a battery box and a plurality of battery monomers combined in series and / or in parallel within the battery box. The battery monomers in the embodiments of the present application can be battery monomers applied in various power batteries or energy storage batteries. The application scenarios of the power batteries include but are not limited to vehicles, ships, aircrafts, spacecrafts, electric tools, electric toys, various mobile terminals, etc. The application scenarios of the energy storage batteries include but are not limited to solar power generation systems, hydroelectric power generation systems, wind power generation systems, etc.

[0073] Figure 1 The battery monomer 20 in some embodiments of the present application is shown as a split structure schematic diagram. The battery monomer 20 as the smallest unit constituting the battery mainly includes a shell 22, a cell assembly 23 and other functional components.

[0074] The shell 22 includes a top wall 221, a bottom wall 222 and a side wall 223 enclosing a closed space with the top wall 221 and the bottom wall 222. At least one of the top wall 221 and the bottom wall 222 can be an end cover assembled with the side wall 223. In addition, the top wall 221 or the bottom wall 222 can also be integrally formed with the side wall 223.

[0075] The top wall 221 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a are electrically connected with the cell assembly 23 to output or input the electric energy of the battery monomer 20. In addition, the top wall 221 can also be provided with a pressure relief mechanism (not shown in the figure) for relieving the internal pressure when the internal pressure or temperature of the battery monomer 20 reaches a threshold value.

[0076] The inside of the shell 22 is used to accommodate the cell assembly 23, electrolyte and other components. In some embodiments of the present application, the shape of the shell 22 can be a regular shape such as a flat body, a cuboid or a square body, so that the side wall 223 includes a first side surface 2231 and a second side surface 2232 which are opposite and substantially planar. In other embodiments of the present application, the shape of the shell 22 can also be substantially cylindrical. The material of the shell 22 is not limited, for example, it can include at least one of copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0077] The cell assembly 23 is the component in the battery cell 20 where the electrochemical reaction occurs. The casing 22 may contain one or more cell assemblies 23. The cell assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the cell assembly 23, while the portions of the positive and negative electrode sheets without active material each constitute a tab 23a. The positive and negative tabs can be located together at one end of the main body, or they can be located at opposite ends of the main body. During charging and discharging, the positive and negative active materials of the battery cell 20 react with the electrolyte, and the tabs 23a connect to the electrode terminals 21a to form a current loop.

[0078] After the excitation-side ultrasonic sensor and the receiving-side ultrasonic sensor are properly installed on the battery cell, the waveform characteristics of the electrical signal output by the receiving-side ultrasonic sensor can be used to detect defects inside the battery cell based on the principle of ultrasonic piezoelectricity. For example, defects such as poor electrolyte wetting, lithium plating, and shedding of active material from the electrode can be detected.

[0079] like Figure 2 and Figure 3 As shown, some embodiments of this application provide a method 300 for mounting an ultrasonic sensor on a battery cell 20, which includes the following steps S301 and S302.

[0080] In step S301, the first ultrasonic sensor 61 is attached to the first adhesive area (not shown in the figure, referring to the area covered by the first ultrasonic sensor 61) on the side wall 223 of the housing 22, and the second ultrasonic sensor 62 is attached to the second adhesive area (not shown in the figure, referring to the area covered by the second ultrasonic sensor 62) on the side wall 223 of the housing 22 opposite to the first adhesive area.

[0081] In step S302, the first positive electrode wire 711 is welded to the first ultrasonic sensor 61, the first negative electrode wire 712 is bonded to the side wall 223, the second positive electrode wire 721 is welded to the second ultrasonic sensor 62, and the second negative electrode wire 722 is bonded to the side wall 223.

[0082] In this embodiment, the shell 22 can be generally a regular shape such as a flattened body, cuboid, or cube, so that its sidewalls 223 include opposing first sidewalls 2231 and second sidewalls 2232. For a shell 22 that is generally cuboid or cube-shaped, its sidewalls 23 may also include opposing third sidewalls and fourth sidewalls that intersect with the first sidewalls 2231 and second sidewalls 2232. Any two opposing sidewalls can be selected as the first sidewall 2232 and the second sidewall 2232 according to actual testing needs. In other embodiments, the shell 22 can also be generally cylindrical.

[0083] When the sidewall 223 of the housing 22 includes a first side 2231 and a second side 2232, the first adhesive area can be located on the first side 2231, the second adhesive area can be located on the second side 2232, the first negative electrode wire 712 is bonded to the first side 2231, and the second negative electrode wire 722 is bonded to the second side 2232.

[0084] The first and second pasting areas can be understood as follows: the orthographic projection of the first pasting area onto the plane containing the second pasting area substantially coincides with the second pasting area, or vice versa. These first and second pasting areas can be determined by researchers based on experience or through multiple experiments.

[0085] In this embodiment, since the first ultrasonic sensor 61 and the second ultrasonic sensor 62 are symmetrically installed, if the two ultrasonic sensors are installed correctly, regardless of whether the first ultrasonic sensor 61 is used as the excitation side and the second ultrasonic sensor 62 is used as the receiving side (e.g., ...), Figure 5A As shown), or using the second ultrasonic sensor 62 as the excitation side and the first ultrasonic sensor 61 as the receiving side (as shown). Figure 5B As shown, the sensing signals obtained from the receiving side should theoretically be identical. In practical applications, the characteristic differences between the two sensing signals are acceptable if they are within a reasonable error range, and the two ultrasonic sensors can be considered to be installed correctly. Therefore, the installation qualification of the two ultrasonic sensors on the battery cell can be evaluated based on the differences in the sensing signals output from the receiving side by the two ultrasonic sensors under forward and reverse excitation.

[0086] Furthermore, since the first ultrasonic sensor 61 and the second ultrasonic sensor 62 are symmetrically mounted, theoretically, if the two ultrasonic sensors are installed correctly, their mounting capacitances (i.e., the capacitance between the first positive wire 711 and the first negative wire 712, and the capacitance between the second positive wire 721 and the second negative wire 722) should be identical. In practical applications, measuring the mounting capacitances of the two ultrasonic sensors and accepting any difference within a reasonable error range indicates that the two ultrasonic sensors are installed correctly. Therefore, the difference in the mounting capacitances of the two ultrasonic sensors can also be used to assess the quality of their installation on the battery cell.

[0087] The installation method provided in this application for installing ultrasonic sensors on battery cells can be used not only for installation qualification assessment but also for test scheme verification. This allows for the determination of the optimal installation scheme for ultrasonic sensors on battery cells, thereby improving the accuracy of quality inspection of battery cells using ultrasonic sensors.

[0088] The following examples illustrate the installation process and post-installation applications of ultrasonic sensors in detail.

[0089] like Figure 2 As shown, in some embodiments of this application, the first positive electrode wire 711 is welded to the center position of the surface of the first ultrasonic sensor 61 (i.e., the geometric center position of the surface of the first ultrasonic sensor 61), and the second positive electrode wire 721 is welded to the center position of the surface of the second ultrasonic sensor 62 (i.e., the geometric center position of the surface of the second ultrasonic sensor 62). This not only ensures reliable installation of the wires and the two ultrasonic sensors, but also allows the two ultrasonic sensors to achieve a relatively consistent installation capacitance after installation.

[0090] In some embodiments, before attaching the first ultrasonic sensor 61 and the second ultrasonic sensor 62, the first attachment area (the area facing the first ultrasonic sensor 61) and the second attachment area (the area facing the second ultrasonic sensor 62) on the surface of the housing 22 can be polished. This reduces the roughness of the attachment area, thereby helping to reduce the attenuation of the ultrasonic signal.

[0091] Before attaching the first ultrasonic sensor 61 and the second ultrasonic sensor 62, the first and second attachment areas can be cleaned, for example, with alcohol. This prevents foreign objects or dirt from adhering, which helps reduce the attenuation of the ultrasonic signal and minimizes interference with it. When attaching the first ultrasonic sensor 61 and the second ultrasonic sensor 62, applying appropriate pressure ensures a more uniform adhesive thickness throughout the application. This not only improves the reliability of the attachment but also reduces the impact of uneven adhesive thickness on the detection results.

[0092] In some embodiments of this application, before attaching the first ultrasonic sensor 61 and the second ultrasonic sensor 62, the inherent capacitance of the first ultrasonic sensor 61 and the inherent capacitance of the second ultrasonic sensor 62 are measured; in response to determining that the inherent capacitance of at least one of the first ultrasonic sensor 61 and the second ultrasonic sensor 62 exceeds the capacitance error range, it is determined to be a defective product and is replaced.

[0093] The inherent capacitance of an ultrasonic sensor, i.e., the capacitance between its two electrodes, is related to the dielectric constant but independent of its installation. It affects the lower frequency limit of the ultrasonic sensor and is a crucial parameter. According to this embodiment, before attaching the ultrasonic sensor, its inherent capacitance can be measured to determine if it is damaged or if its performance parameters have deviated. This avoids affecting the accuracy of detection after installation due to a defective ultrasonic sensor, reducing the cost of manpower and resources.

[0094] In some embodiments, after the two ultrasonic sensors are installed, the installation of the two ultrasonic sensors on the battery cell is evaluated based on the difference in the sensing signals output by the two ultrasonic sensors under forward and reverse excitation, respectively. For example... Figure 4 As shown, after completing the aforementioned step S302, the method 400 of this embodiment further includes:

[0095] Step S403: Using the first ultrasonic sensor as the excitation side and the second ultrasonic sensor as the receiving side, obtain the positive excitation sensing signal output by the second ultrasonic sensor.

[0096] Step S404: Using the second ultrasonic sensor as the excitation side and the first ultrasonic sensor as the receiving side, obtain the reverse excitation sensing signal output by the first ultrasonic sensor; and

[0097] Step S405: Evaluate the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell based on the positive excitation sensing signal and the reverse excitation sensing signal.

[0098] In some embodiments, step S403 above may be implemented as follows: Figure 5A As shown, a function generator 30, an amplifier 40, and an oscilloscope 50 are provided. The function generator 30 and the amplifier 40 are connected. The amplifier 40 is connected to the first positive wire 711 and the first negative wire 712, thereby establishing a current loop with the first ultrasonic sensor 61 and the side wall of the battery cell 20. The oscilloscope 50 is electrically connected to the second positive wire 721 and the second negative wire 722, thereby establishing a current loop with the second ultrasonic sensor 62 and the side wall of the battery cell 20. Then, the positive excitation sensing signal output by the oscilloscope 50 is acquired.

[0099] Similarly, step S404 above can be implemented in the following manner: Figure 5BAs shown, the function generator 30, the amplifier 40 and the oscilloscope 50 are provided, the function generator 30 and the amplifier 40 are connected (the same set of equipment can be used in step S403); the amplifier 40 is connected with the second positive lead wire 721 and the second negative lead wire 722, so as to form a current loop with the second ultrasonic sensor 62 and the shell side wall of the battery monomer 20; the oscilloscope 50 is electrically connected with the first positive lead wire 711 and the first negative lead wire 712, so as to form a current loop with the first ultrasonic sensor 61 and the shell side wall of the battery monomer 20; then, the reverse excitation sensing signal output by the oscilloscope 50 is collected.

[0100] In some embodiments, the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer can be evaluated based on the forward excitation sensing signal and the reverse excitation sensing signal. The above step S405 comprises:

[0101] In response to determining that the feature difference between the forward excitation sensing signal and the reverse excitation sensing signal is within the error range, it is determined that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer is qualified; and

[0102] In response to determining that the feature difference between the forward excitation sensing signal and the reverse excitation sensing signal is beyond the error range, it is determined that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer is unqualified.

[0103] After the installation of the two ultrasonic sensors is completed, the equipment can be left for a period of time (for example, 2 hours) before the ultrasonic detection in the above steps S403 and S404, so as to cool the welding points and adapt the equipment to the ambient temperature, so that more accurate detection results can be obtained.

[0104] Before the above step S301, different test schemes for installing the two ultrasonic sensors on the battery monomer can be determined in advance based on a plurality of sensitive factors. Referring to Table 1 shown below, the plurality of sensitive factors include at least one of the following: the positions of the first and second adhesive areas on the shell side wall of the battery monomer, the polishing conditions of the first and second adhesive areas, the glue application area ratios of the first and second adhesive areas, the welding point specifications of the first and second ultrasonic sensors, and the ambient temperature.

[0105] Test protocol Paste position Polish condition Glue area ratio Weld point specification Ambient temperature Test protocol 1 3 / 4 height No polish 100％ 0.2 mm 25℃ Test protocol 2 1 / 2 height Full polish 100％ 0.2 mm 25℃ Test protocol 3 1 / 2 height No polish 100％ 0.2 mm 45℃ Test protocol 4 1 / 2 height No polish 100％ 0.2 mm 60℃ Test protocol 5 1 / 2 height No polish 100％ 0.2 mm 25℃ Test protocol 6 1 / 2 height No polish 100％ 0.4 mm 25℃ Test protocol 7 1 / 2 height No polish 50％ 0.2 mm 25℃ Test protocol 8 1 / 2 height No polish 25％ 0.2 mm 25℃ Test protocol 9 1 / 4 height No polish 100％ 0.2 mm 25℃

[0106] Table 1: Test scheme list determined based on a plurality of sensitive factors

[0107] Reference Figure 2As shown, the paste position refers to the proportion of the height h1 of the lower edge of the paste area relative to the bottom of the battery monomer 20 to the height h2 of the battery monomer 20. The polishing condition can be no polishing (the roughness of the paste area is basically consistent with the roughness of other areas of the shell) or polishing according to a certain accuracy standard (the roughness of the paste area is smaller than the roughness of other areas of the shell). The glue area ratio refers to the proportion of the glue area S1 in the paste area to the area S2 of the paste area (S2 is equal to the area covered by the ultrasonic sensor on the side wall); the welding point specification refers to the diameter of the welding point; and the ambient temperature refers to the ambient temperature around the ultrasonic sensor.

[0108] Based on the above-mentioned design of the test scheme, referring to the foregoing steps S301 and S302, two ultrasonic sensor samples can be symmetrically installed on the battery monomer, and a sensing signal output by one of the ultrasonic sensor samples can be obtained by taking the one ultrasonic sensor sample as the excitation side and the other ultrasonic sensor sample as the receiving side. The inventors of the present application obtained the following analysis results by analyzing the sensing signals obtained by the above-mentioned respective test schemes.

[0109] I. Under different welding point specifications, the waveform, amplitude and flight time (the time from the transmitter to the receiver of the ultrasonic signal is defined as the flight time) of the sensing signal are basically consistent, so the influence of the welding point size on the sensing signal can be ignored.

[0110] II. Under different polishing conditions, the waveforms of the sensing signals are basically consistent, but compared with the non-polishing test scheme, after the paste area is completely polished, the sensing signal attenuates less and has a higher amplitude. Polishing or not polishing the paste area can be selected according to actual needs.

[0111] III. As shown in Figure 6A , under different paste positions, the waveform and amplitude of the sensing signal have obvious differences, so the influence of the paste position on the sensing signal is obvious.

[0112] IV. Under different ambient temperatures, the waveform and amplitude of the sensing signal change little. Since the test is usually carried out in a constant-temperature room, the temperature fluctuation is very small, so the influence of the ambient temperature on the sensing signal can be ignored.

[0113] V. As shown in Figure 6B , under different glue area ratios, the waveform and amplitude of the sensing signal have obvious differences, so the influence of the glue area ratio on the sensing signal is obvious.

[0114] In some embodiments, the installation of the two ultrasonic sensors on the battery monomer can also be evaluated based on the difference in the installation capacitance of the two ultrasonic sensors on the battery monomer. The method of this embodiment further comprises the following steps after the foregoing step S302:

[0115] determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer is qualified in response to determining that the difference ratio of the first capacitance and the second capacitance is less than the ratio threshold; and

[0116] determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer is unqualified in response to determining that the difference ratio of the first capacitance and the second capacitance is not less than the ratio threshold.

[0117] The difference ratio k of the first capacitance and the second capacitance is, for example, k = |C2-C1|*100% / C1, where C1 is the first capacitance and C2 is the second capacitance.

[0118] In some embodiments of the present application, the ratio threshold can be determined in the following manner:

[0119] N ultrasonic sensor samples are provided, and N levels of gradient test installation capacitances corresponding to the N ultrasonic sensor samples are designed, where N≥3;

[0120] The first ultrasonic sensor sample is installed on the first adhesive area of the side wall of the shell, and the first ultrasonic sensor sample obtains the first level of gradient test installation capacitance;

[0121] The second to Nth ultrasonic sensor samples are sequentially replaced and installed on the second adhesive area of the side wall of the shell opposite to the first adhesive area, and correspondingly obtain the second to Nth levels of gradient test installation capacitances, and for the installed nth ultrasonic sensor sample: the first ultrasonic sensor sample is taken as the excitation side, the nth ultrasonic sensor sample is taken as the receiving side, the forward excitation sensing signal output by the nth ultrasonic sensor sample is obtained, and the nth ultrasonic sensor sample is taken as the excitation side, the first ultrasonic sensor sample is taken as the receiving side, the reverse excitation sensing signal output by the first ultrasonic sensor sample is obtained, where 2≤n≤N; and

[0122] The ratio threshold k is determined based on the forward excitation sensing signals and the reverse excitation sensing signals respectively obtained by the installation of the second to Nth ultrasonic sensor samples.

[0123] For example, in one embodiment, four ultrasonic sensor samples are provided, four levels of gradient test installation capacitances are designed for them, three groups of comparative tests are carried out, and three groups of comparative test data are obtained.

[0124] Comparative Test 1: install the first ultrasonic sensor sample on the first adhesive area of the shell, and make it obtain the test installation capacitance C01 of the first level gradient, install the second ultrasonic sensor sample on the second adhesive area of the shell, and make it obtain the test installation capacitance C02 (increased by 3.5% compared with C01) of the second level gradient. Obtain the positive excitation sensing signal and the reverse excitation sensing signal, and compare the difference between the main wave packet amplitudes of the two, the deviation is less than 10%, and the installation capacitance difference is basically acceptable.

[0125] Comparative Test 2: replace the third ultrasonic sensor sample on the second adhesive area of the shell, and make it obtain the test installation capacitance C03 (increased by 5% compared with C01) of the third level gradient. As shown in Figure 7A , the obtained positive excitation sensing signal and reverse excitation sensing signal have obvious differences in waveform and amplitude, and the installation capacitance difference is unacceptable.

[0126] Comparative Test 3: replace the fourth ultrasonic sensor sample on the second adhesive area of the shell, and make it obtain the test installation capacitance C04 (increased by 7.8% compared with C01) of the fourth level gradient. As shown in Figure 7B , the obtained positive excitation sensing signal and reverse excitation sensing signal have obvious differences in waveform and amplitude, and the installation capacitance difference is unacceptable.

[0127] Based on the result data of comparative tests 1, 2, and 3, a reasonable correction coefficient λ (for example, 0.86) is set, and the difference ratio k of the first capacitance and the second capacitance is determined to be 3% which is more appropriate.

[0128] As shown in Figure 8 , the method 800 for installing an ultrasonic sensor on a battery monomer provided by some embodiments of the present application, wherein the shape of the shell of the battery monomer is substantially a flat body, a cuboid or a square body, so that the side wall includes opposite first and second side surfaces. The method 800 specifically includes the following steps:

[0129] Step S801: Before the first ultrasonic sensor and the second ultrasonic sensor are pasted, the inherent capacitance of the first ultrasonic sensor and the inherent capacitance of the second ultrasonic sensor are measured to ensure that they are qualified products;

[0130] Step S802: Position the first adhesive area and the second adhesive area on the first side surface and the second side surface of the shell, and arrange them oppositely;

[0131] Step S803: Use a cleaning agent such as alcohol to clean the first adhesive area, the second adhesive area and the surrounding area;

[0132] Step S804: Apply glue to the first adhesive area and the second adhesive area, and the glue completely covers the adhesive area;

[0133] Step S805: correspondingly paste the first ultrasonic sensor and the second ultrasonic sensor in the first pasting area and the second pasting area, and apply appropriate pressing force;

[0134] Step S806: weld the first positive electrode wire with the first ultrasonic sensor, paste the first negative electrode wire with the first side surface, weld the second positive electrode wire with the second ultrasonic sensor, and paste the second negative electrode wire with the second side surface;

[0135] Step S807: take the first ultrasonic sensor as the excitation side and the second ultrasonic sensor as the receiving side to obtain a forward excitation sensing signal; then, take the second ultrasonic sensor as the excitation side and the first ultrasonic sensor as the receiving side to obtain a reverse excitation sensing signal; in some embodiments, step S807 can also include: measuring a first capacitance between the first positive electrode wire and the first negative electrode wire, and a second capacitance between the second positive electrode wire and the second negative electrode wire by using a capacitance measuring instrument;

[0136] Step S808: evaluate the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer, and use the first ultrasonic sensor and the second ultrasonic sensor for defect detection of the battery monomer after ensuring that the installation is qualified.

[0137] The installation method provided by the embodiments of the present application can realize the optimal installation of the ultrasonic sensor on the battery monomer, thereby improving the accuracy of quality detection of the battery monomer by using the ultrasonic sensor.

[0138] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method of mounting an ultrasonic sensor on a battery cell, the battery cell including a case including a top wall, a bottom wall, and a side wall enclosing a closed space with the top wall and the bottom wall, characterized by, The method comprises: pasting a first ultrasonic sensor at a first pasting area of the side wall and a second ultrasonic sensor at a second pasting area of the side wall opposite to the first pasting area; and welding a first positive electrode lead wire to the first ultrasonic sensor, bonding a first negative electrode lead wire to the side wall, welding a second positive electrode lead wire to the second ultrasonic sensor, and bonding a second negative electrode lead wire to the side wall; obtaining a forward excitation sensing signal output by the second ultrasonic sensor with the first ultrasonic sensor as an excitation side and the second ultrasonic sensor as a receiving side; and obtaining a reverse excitation sensing signal output by the first ultrasonic sensor with the second ultrasonic sensor as an excitation side and the first ultrasonic sensor as a receiving side; and evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer based on the forward excitation sensing signal and the reverse excitation sensing signal.

2. The method of claim 1, wherein the side wall comprises opposite first and second side surfaces, the first pasting area is located at the first side surface, the second pasting area is located at the second side surface, the first negative electrode lead wire is bonded to the first side surface, and the second negative electrode lead wire is bonded to the second side surface.

3. The method of claim 1, wherein, Further comprising: obtaining the forward excitation sensing signal output by the second ultrasonic sensor with the first ultrasonic sensor as an excitation side and the second ultrasonic sensor as a receiving side comprises: providing a function generator, an amplifier, and an oscilloscope, and connecting the function generator and the amplifier; connecting the amplifier to the first positive electrode lead wire and the first negative electrode lead wire, and electrically connecting the oscilloscope to the second positive electrode lead wire and the second negative electrode lead wire; and collecting the forward excitation sensing signal output by the oscilloscope; obtaining the reverse excitation sensing signal output by the first ultrasonic sensor with the second ultrasonic sensor as an excitation side and the first ultrasonic sensor as a receiving side comprises: providing a function generator, an amplifier, and an oscilloscope, and connecting the function generator and the amplifier; connecting the amplifier to the second positive electrode lead wire and the second negative electrode lead wire, and electrically connecting the oscilloscope to the first positive electrode lead wire and the first negative electrode lead wire; and collecting the reverse excitation sensing signal output by the oscilloscope.

4. The method of claim 1, wherein, evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer based on the forward excitation sensing signal and the reverse excitation sensing signal comprises: in response to determining that the characteristic difference of the forward excitation sensing signal and the reverse excitation sensing signal is within an error range, determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery monomer is qualified; and In response to determining that the characteristic difference between the forward excitation sensing signal and the reverse excitation sensing signal exceeds the error range, determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell is unqualified.

5. The method of claim 1, wherein, Further comprising: providing a capacitance measuring instrument; measuring, using the capacitance measuring instrument, a first capacitance between the first positive electrode lead and the first negative electrode lead, and a second capacitance between the second positive electrode lead and the second negative electrode lead; based on the first capacitance and the second capacitance, evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell.

6. The method of claim 5, wherein, Based on the first capacitance and the second capacitance, evaluating the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell, comprising: in response to determining that the difference ratio of the first capacitance and the second capacitance is less than a ratio threshold, determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell is qualified; and in response to determining that the difference ratio of the first capacitance and the second capacitance is not less than the ratio threshold, determining that the installation of the first ultrasonic sensor and the second ultrasonic sensor on the battery cell is unqualified.

7. The method of claim 6, wherein, The ratio threshold is determined in the following way: providing N ultrasonic sensor samples, and designing N-level gradient test installation capacitances corresponding to the N ultrasonic sensor samples, where N≥3; installing the first ultrasonic sensor sample in the first pasting area, and making the first ultrasonic sensor sample obtain a first-level gradient test installation capacitance; in the second pasting area, sequentially replacing and installing the second to Nth ultrasonic sensor samples and making them correspondingly obtain second to Nth-level gradient test installation capacitances, and for the installed nth ultrasonic sensor sample: taking the first ultrasonic sensor sample as the excitation side and the nth ultrasonic sensor sample as the receiving side to obtain a forward excitation sensing signal output by the nth ultrasonic sensor sample; taking the nth ultrasonic sensor sample as the excitation side and the first ultrasonic sensor sample as the receiving side to obtain a reverse excitation sensing signal output by the first ultrasonic sensor sample, where 2≤n≤N; and based on the forward excitation sensing signals and the reverse excitation sensing signals obtained by the installation of the second to Nth ultrasonic sensor samples respectively, determining the ratio threshold.

8. The method of claim 1, wherein, Further comprising: before pasting the first ultrasonic sensor and the second ultrasonic sensor, based on a plurality of sensitive factors, determining a test scheme for installing the first ultrasonic sensor and the second ultrasonic sensor on the battery cell, The plurality of sensitive factors include at least one of: positions of the first and second pasting areas on the side wall, polishing conditions of the first and second pasting areas, glue coating area proportions of the first and second pasting areas, pad specifications on the first and second ultrasonic sensors, and an ambient temperature.

9. The method of claim 1, wherein, welding the first positive electrode lead and the first ultrasonic sensor includes welding the first positive electrode lead and a center position of a surface of the first ultrasonic sensor; welding the second positive electrode lead and the second ultrasonic sensor includes welding the second positive electrode lead and a center position of a surface of the second ultrasonic sensor.

10. The method of any one of claims 1 to 9, wherein, Further comprising: polishing the first and second pasting areas before pasting the first and second ultrasonic sensors.

11. The method of any one of claims 1 to 9, wherein, Further comprising: cleaning the first and second pasting areas before pasting the first and second ultrasonic sensors.

12. The method of any one of claims 1 to 9, wherein, Further comprising: measuring intrinsic capacitances of the first and second ultrasonic sensors before pasting the first and second ultrasonic sensors; in response to determining that the intrinsic capacitance of at least one of the first and second ultrasonic sensors is out of a capacitance error range, determining that it is a defective product and replacing it.

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