A patch-type battery bulge monitoring device, method and battery structure

Abstract

The present application relates to battery detection technical field, disclose a kind of patch type battery bulge monitoring device, method and battery structure, comprising: flexible substrate, passive wireless type surface acoustic wave sensor and electrical lead structure;The side of the flexible substrate is used to adhere on the surface of the metal shell of the battery to be measured;The other side of the flexible substrate is closely attached with the passive wireless type surface acoustic wave sensor;The electrical lead structure is located at the side of the passive wireless type surface acoustic wave sensor away from the flexible substrate, and the electrical lead structure is used to feedback the monitoring result of the passive wireless type surface acoustic wave sensor to the outside world;It can realize the real-time accurate monitoring of passive wireless stress-strain information generated by battery bulge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery detection, in particular to a patch type battery bulging monitoring device, method and battery structure. BACKGROUND

[0002] Lithium ion batteries, as a widely used battery type, may have a bulging phenomenon during operation. The causes of the bulging phenomenon of the battery may be the generation of gas due to internal factors such as aging, electrolyte decomposition, and destruction of the electrode plate structure, or may be the damage of the battery shell caused by external factors such as extrusion and impact. Bulging can cause damage to the internal structure of the battery, affect the performance and stability of the battery, reduce the service life and working efficiency of the battery, and even may exist safety hazards, such as short circuit, overheating, explosion, etc. Therefore, it is of great significance to monitor the stress and strain parameters of the battery in the process of cyclic charging and discharging in real time, and to evaluate the bulging state of the battery;

[0003] At present, the monitoring of the battery bulging phenomenon mainly includes visual and tactile inspection, manual physical measurement, and the use of externally installed sensors. Among them, visual and tactile inspection can only observe or touch the battery shell with the naked eye, which can preliminarily judge the bulging problem simply and intuitively, but cannot provide quantitative data. Manual physical measurement, i.e. using a micrometer, a vernier caliper, and a hand-held pressure gauge to measure the shape and size changes of the battery shell, can provide quantitative data, but cannot monitor the bulging phenomenon in real time, and also has a large measurement error. With the help of externally installed sensors, the strain sensor is installed on the battery metal shell, and the stress and strain of the shell are measured to evaluate the bulging condition. Common types of strain sensors include resistance type, capacitance type, and strain gauge type. These sensors can monitor the bulging condition in real time and provide quantitative data, but most of them are active and wired sensors that require external power supply, and also require complex external electronic circuits and systems to realize the transmission of signals from the sensor to the electronic device. At the same time, the installation of these strain sensors and the battery on the metal shell usually involves punching and other lossy operations, and the battery of the sensor itself also has a service life, which is very troublesome to replace. Secondly, to detect the weak strain generated by the bulging, the sensitivity of the sensor is also very demanding.

[0004] Therefore, how to solve the problem that the prior art cannot passively and wirelessly monitor the stress and strain parameters and the degree of bulging generated by the battery bulging in real time with high precision and provide quantitative data has become a technical problem to be solved by those skilled in the art. SUMMARY

[0005] The application provides a patch type battery bulge monitoring device, a patch type battery bulge monitoring method and a battery structure to solve the above technical problems and realize real-time and accurate monitoring of stress and strain generated by battery bulge and accurate quantitative measurement of the degree of bulge.

[0006] To solve the above technical problems, an embodiment of the application provides a patch type battery bulge monitoring device.

[0007] The patch type battery bulge monitoring device comprises a flexible substrate, a passive wireless surface acoustic wave sensor and an electrical lead-out structure.

[0008] One side of the flexible substrate is used to be attached to the surface of the metal shell of the battery to be measured.

[0009] The other side of the flexible substrate is closely attached to the passive wireless surface acoustic wave sensor.

[0010] The electrical lead-out structure is arranged on the side of the passive wireless surface acoustic wave sensor away from the flexible substrate, and the electrical lead-out structure is used to feed back the monitoring result of the passive wireless surface acoustic wave sensor to the outside world.

[0011] Further, the flexible substrate is a bendable flexible material.

[0012] Further, the electrical lead-out structure is connected with a patch type antenna.

[0013] Further, the passive wireless surface acoustic wave sensor is prepared through a photolithography and stripping process.

[0014] Another embodiment of the application provides a battery bulge monitoring method applied to the patch type battery bulge monitoring device, and the method comprises the following steps.

[0015] Respective deformation data reflecting the deformation degree of the battery to be measured is monitored and output, wherein the deformation data comprises propagation speed and wavelength.

[0016] The propagation speed and the wavelength are processed based on a preset frequency calculation formula to obtain resonance frequency data of the sensor.

[0017] The resonance frequency data is processed according to the linear relationship among resonance frequency, bending angle and bending strain to obtain real-time bending angle value and real-time bending strain value of the battery to be measured respectively.

[0018] The monitoring result reflecting the bulge degree of the battery to be measured is generated based on the real-time bending angle value and the real-time bending strain value.

[0019] Further, the processing of the propagation speed and the wavelength based on the preset frequency calculation formula to obtain resonance frequency data comprises the following steps.

[0020] The frequency calculation formula is represented by the following expression:

[0021]

[0022] Wherein, v is the propagation speed, λ is the wavelength, and f is the resonance frequency.

[0023] Further, the resonance frequency data is processed according to the linear relationship among the resonance frequency, the bending angle and the bending strain, to obtain the real-time bending angle value and the real-time bending strain value of the battery to be measured, respectively, including:

[0024] According to the resonance frequency data, an equivalent elliptical model of the bulging battery to be measured is constructed;

[0025] The bending curvature in the equivalent elliptical model is calculated;

[0026] The real-time bending angle value is calculated according to the bending curvature, and the real-time bending strain value is calculated based on the beam bending theory.

[0027] Further, the monitoring result reflecting the bulging degree of the battery to be measured is generated based on the bending angle value and the bending strain value, including:

[0028] If the bending angle value and the bending strain value are both within the preset safe interval, monitoring information with an adjusted battery charging strategy is generated;

[0029] If the bending angle value and the bending strain value are both within the preset non-safe interval, monitoring information with a reminder to replace the battery is generated.

[0030] Another embodiment of the present application provides a battery structure, which comprises a battery to be measured, a terminal device and a patch type battery bulging monitoring device as described above;

[0031] Further, the terminal device is in communication connection with the electrical lead-out structure.

[0032] Further, the terminal device comprises one or more of the following: a mobile phone terminal, a notebook computer terminal or a smart watch terminal.

[0033] Compared with the prior art, the beneficial effects of the embodiments of the present application are at least one of the following:

[0034] (1) A piezoelectric film is prepared on a flexible substrate, a passive wireless surface acoustic wave sensor is prepared through a photolithography and stripping process, and is attached to the surface of the metal shell of the battery to be measured, so that the stress and strain information and the bulging condition of the battery to be measured can be monitored in real time, thereby obtaining quantitative data;

[0035] (2) In the process of attaching monitoring, the electrical lead-out structure of the passive wireless surface acoustic wave sensor is connected with the antenna, the received radio signals are reflected to the air through the antenna, and the radio frequency signals of the measurement information of stress and strain and the size of the bulge are transmitted to the smart terminal for interaction, so that the stress and strain generated by the battery bulge can be monitored in real time and accurately in a passive and wireless manner. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a structure schematic diagram of a patch type battery bulge monitoring device in an embodiment of the present application;

[0037] Figure 2 is a product schematic diagram of a patch type battery bulge monitoring device in an embodiment of the present application;

[0038] Figure 3 is a preparation flow chart of a patch type battery bulge monitoring device in an embodiment of the present application;

[0039] Figure 4 is a flexibility schematic diagram of a patch type battery bulge monitoring device in an embodiment of the present application;

[0040] Figure 5 is a flow chart of a battery bulge monitoring method in an embodiment of the present application;

[0041] Figure 6 is a two-port parameter definition diagram of a battery bulge monitoring method in an embodiment of the present application;

[0042] Figure 7 is an equivalent ellipse model based on bending deformation of a battery bulge monitoring method in an embodiment of the present application;

[0043] Figure 8 is a correlation between bending angle and bending curvature of a battery bulge monitoring method in an embodiment of the present application;

[0044] Figure 9 is a structure schematic diagram of a battery structure in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. The purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0046] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0048] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0049] One embodiment of the present invention provides a patch-type battery bulging monitoring device, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of a patch-type battery bulging monitoring device according to one embodiment of the present invention, including: a flexible substrate 1, a passive wireless surface acoustic wave sensor 2, and an electrical lead-out structure 3. Specifically:

[0050] One side of the flexible substrate 1 is used to attach to the surface of the metal casing of the battery under test;

[0051] In the embodiment, in order to make the device conform to the surface of the metal shell of the battery to be measured, that is, to make the device conform to the surface of the metal shell of the battery to be measured, the flexible substrate 1 is a flexible material, for example, a polyimide (PI) material with good flexibility, which is selected as the substrate of the device, and the preparation is carried out on the substrate, so that the monitoring device has the characteristics of being flexible, stretchable and deformed, thereby meeting the requirement of monitoring the bulge of the battery.

[0052] The passive wireless surface acoustic wave sensor 2 is a sensor combining wireless communication technology, piezoelectric effect and surface acoustic wave propagation characteristics, which is composed of a piezoelectric film, interdigital transducers (IDTs) and reflective gratings in the embodiment. The main working principle is as follows:

[0053] On the surface of the piezoelectric film, a surface acoustic wave propagating along the surface of the material can be excited by a suitable excitation method (such as an interdigital transducer). When the surface acoustic wave encounters a physical or chemical quantity to be measured during propagation, such as temperature, pressure, humidity, chemical substances, etc., these external factors will interact with the surface acoustic wave, thereby changing its propagation characteristics, such as wave speed, amplitude, phase, etc. By receiving and detecting the changes of the surface acoustic wave after propagation, the information of the external factors can be derived. Usually, the same or similar IDT as the transmitting IDT is used as the receiving IDT to convert the surface acoustic wave into an electrical signal, and then further signal processing and demodulation are performed to obtain the value of the measured quantity.

[0054] In the embodiment, the passive wireless surface acoustic wave sensor 2 is prepared by photolithography and stripping process.

[0055] The preparation process is described in detail as follows. For details, refer to Figure 3 , Figure 3 The preparation flow chart of the patch type battery bulge monitoring device in the embodiment is shown,

[0056] First, a piezoelectric film is prepared on the flexible substrate 1. In the embodiment, the piezoelectric film is sputtered onto the flexible substrate by magnetron sputtering. The material of the piezoelectric film can be selected from ZnO, AlN, AlScN, PZT, PVDF, etc. These materials have good flexibility and plasticity, and the magnetron sputtering method used in the embodiment makes the adhesion and adhesion of the film stronger, thereby improving the durability of the device.

[0057] Then, the passive wireless acoustic surface wave sensor is prepared by performing a photoetching and stripping process on the piezoelectric film, specifically: the photoresist is spin-coated on the piezoelectric film, and the photoresist is exposed and developed to form a photoresist pattern, then the metal electrode layer of the piezoelectric film is deposited by magnetron sputtering, finally, the interdigital transducer is prepared by stripping and removing the photoresist, and the reflective grating is arranged on both sides of the film to complete the preparation of the passive wireless acoustic surface wave sensor, and the specific product schematic diagram can be referred to Figure 2 , Figure 2 The product schematic diagram of the patch type battery bulge monitoring device in one of the embodiments of the present application is shown.

[0058] According to the description of the specific structure of the above device and the preparation process of the sensor, it can be known that the patch type sensor monitoring device has excellent flexibility, compared with the traditional rigid sensor device, not only the strain measurement range is larger but also it is very sensitive to bending strain, and it can be directly attached to the surface of the metal shell of the battery to be measured, and the stress and strain parameters of the measured area can be monitored in real time, so as to judge whether the battery to be measured has bulge phenomenon, and the degree of battery bulge can be evaluated according to the monitoring result, and the physical display of the device is shown in Figure 4 , Figure 4 The flexibility schematic diagram of the patch type battery bulge monitoring device in one of the embodiments of the present application is shown, and it can be seen that it has excellent flexibility.

[0059] In the monitoring process of the sensor in the embodiment, the electrical lead-out structure 3 is arranged on the side of the passive wireless acoustic surface wave sensor 2 away from the flexible substrate 2, and the electrical lead-out structure 3 is used for feeding back the monitoring result of the passive wireless acoustic surface wave sensor 2 to the outside. Specifically, the electrical lead-out structure 3 is connected with the patch type antenna, and the electrical lead-out structure 3 can also be connected with other communication equipment, so as to realize the feedback of the monitoring result to the outside.

[0060] In summary, the patch type battery bulge monitoring device in the embodiment of the present application is a passive wireless sensor, which does not need external power supply, is suitable for the application scenario of monitoring battery bulge which needs long-term monitoring, is not easy to wiring or needs to reduce energy consumption, and has excellent flexibility, and can accurately monitor the deformation data generated by the battery bulge to be measured.

[0061] Another embodiment of the present application provides a battery bulge monitoring method applied to the above-mentioned patch type battery bulge monitoring device, as shown in Figure 5 , Figure 5 The flow chart of the battery bulge monitoring method in one of the embodiments of the present application is shown, and the method specifically includes steps S1-S4:

[0062] Steps S1-S2, respectively monitor and output deformation data reflecting the deformation degree of the battery to be measured, wherein the deformation data includes propagation speed and wavelength;

[0063] Based on the preset frequency calculation formula, the propagation speed and the wavelength are processed to obtain the resonant frequency data of the sensor.

[0064] The above steps are described in detail as follows:

[0065] First, we explore the influence of the deformation data generated by the battery to be measured on the surface wave sensor. As known from the working principle of the above passive wireless surface acoustic wave sensor 2, in this embodiment, the passive wireless surface acoustic wave sensor 2 includes two groups of interdigital transducers, wherein one group of interdigital transducers is used for monitoring signal input and converting the monitoring signal into a surface acoustic wave through inverse piezoelectric effect, and then transmitting the monitoring signal to another group of interdigital transducers through the prepared piezoelectric film, and finally converting it into an electrical signal output through positive piezoelectric effect. Further, we can explore the factors affecting the resonant frequency of the surface acoustic wave sensor through the relationship between the above signals, specifically:

[0066] The reflection coefficient S 11 and the transmission coefficient S 12 can be obtained by calculating the ratio of the above signals, and both are defined as parameter S, which is represented by the following formula:

[0067]

[0068]

[0069] Wherein a1 is the incident voltage wave at the input end, b1 is the voltage wave reflected by the reflective grating at the input end, a2 is the reflected voltage wave at the output end, and b2 is the outgoing voltage wave at the output end, as shown in Figure 6 , Figure 6 shows the two-port parameter definition diagram of the battery bulging monitoring method in one embodiment of the present application. In this embodiment, the frequency is taken as the abscissa, and the loss defined by S 11 and the transmission coefficient S 12 is taken as the ordinate, and the abscissa corresponding to the lowest and highest points of the loss is the resonant frequency f of the passive wireless surface acoustic wave sensor 2.

[0070] In the process of battery bulge monitoring by the passive wireless surface acoustic wave sensor 2, the stress information generated by the deformation of the battery metal shell will be transmitted to the piezoelectric film, causing the piezoelectric film to produce bending deformation, so the density and elastic constant of the piezoelectric film will also change, thereby changing the propagation speed of the surface acoustic wave sensor, and due to the deformation of the sensor, the propagation path of the sensor changes, which will increase the actual length of the surface acoustic wave delay line between the two interdigital transducers (the finger spacing of the interdigital transducer), causing the time of the propagating surface acoustic wave to reach the IDT to change, that is, the wavelength of the surface acoustic wave sensor changes, so the propagation speed and wavelength of the surface acoustic wave sensor are closely related to the degree of deformation of the sensor, that is, the propagation speed and wavelength of the surface acoustic wave sensor can truly reflect the deformation data of the battery to be measured, so:

[0071] The frequency calculation formula is represented by the following expression:

[0072]

[0073] Where v is the propagation speed, λ is the wavelength, and f is the resonant frequency.

[0074] Step S3, according to the linear relationship between the resonant frequency, the bending angle and the bending strain, the resonant frequency data is processed to obtain the real-time bending angle value and the real-time bending strain value of the battery to be measured.

[0075] Next, we will further explore the relationship between the resonant frequency and the bending angle and the bending strain generated by the deformation of the battery:

[0076] First, according to the resonant frequency data, an equivalent elliptical model of the battery bulge to be measured is constructed.

[0077] In this embodiment, we can calculate the bending angle and the bending strain by the equivalent elliptical model and the mathematical equation of the bending curvature, and directly bring the parameter equation of the ellipse into the curvature formula, where the curvature formula and the parameter equation of the ellipse are not repeated here, the following is the specific derivation process of the linear relationship between the resonant frequency, the bending angle and the bending strain in step S3, which can be referred to Figure 7 The equivalent elliptical model is shown in the figure, where A represents the center position of the bending deformation:

[0078] The equivalent elliptical model is represented by the following formula:

[0079]

[0080] Where a and b are the lengths of the major axis and the minor axis of the ellipse respectively, t is the parameter, and K(t) is the equivalent elliptical model.

[0081] Then, the real-time bending angle value is calculated according to the equivalent ellipse model;

[0082] The bending angle is represented by the following formula:

[0083]

[0084] Wherein, d2 and d1 are the distance of the center position of the bending deformation from the origin and the distance of the two ends of the bending deformation from the origin, and θ is the bending angle.

[0085] Then, the bending curvature in the equivalent ellipse model is calculated according to the real-time bending angle value;

[0086] In this embodiment, the bending angle is classified and discussed, and the bending curvature corresponding to the equivalent ellipse model A point of different bending angle values is calculated in combination with the equivalent ellipse model, and the specific linear relationship between them is as shown in Figure 8 It can be seen that there is a good linear relationship between the bending angle θ and the bending curvature K.

[0087] The bending curvature is represented by the following formula:

[0088]

[0089] Next, the relationship between the bending strain value and the bending curvature K is continued to be derived:

[0090] We know that the bending curvature K and the curvature radius R are inversely related, and in this embodiment, the real-time bending strain value can be calculated based on the beam bending theory,

[0091] The bending strain value is represented by the following formula:

[0092]

[0093] Wherein, y is the vertical distance of the center axis, d is the thickness of the sensor device, R is the curvature radius, and ε is the bending strain value.

[0094] As can be seen, the bending curvature K and the bending strain ε also have a linear relationship, so the bending angle and the bending strain also have a linear relationship.

[0095] And in step S2, we know that because the resonant frequency f of the surface acoustic wave sensor has a clear linear relationship with the deformation degree, it can be deduced that the resonant frequency should also have a good linear relationship with the above-mentioned bending angle and bending strain.

[0096] Step S4: Based on the real-time bending angle value and the real-time bending strain value, a monitoring result reflecting the degree of bulging of the battery under test is generated. In this embodiment, the specific monitoring method is as follows:

[0097] If both the bending angle value and the bending strain value are within a preset safe range, then monitoring information for adjusting the battery charging strategy is generated.

[0098] If both the bending angle value and the bending strain value are within a preset unsafe range, monitoring information is generated to remind the user to replace the battery.

[0099] As can be seen from the above discussion, based on the calculated linear relationship, the real-time bending angle and real-time bending strain value corresponding to the resonant frequency data can be obtained. Since the electrical lead-out structure on the sensor is connected to the antenna in this embodiment, the surface acoustic wave sensor can provide feedback to the outside world and emit radio frequency signals containing the resonant frequency. Therefore, as long as the user receives the resonant frequency, it can monitor the quantitative data information of battery bulging through the linear relationship between the resonant frequency and bending deformation.

[0100] In summary, the battery bulging monitoring method of this invention explores and derives the relationship between the resonant frequency of the surface acoustic wave sensor and the degree of deformation of the battery under test. Then, by calculating the bending angle and bending strain, a linear relationship between the two and the resonant frequency is obtained. Therefore, based on the linear correlation between the three, a radio frequency signal including the resonant frequency data can be transmitted to a terminal device to determine and monitor whether the battery is bulging and the degree of bulging, and obtain accurate quantitative evaluation results. This enables passive and wireless real-time accurate monitoring of the stress and strain generated by battery bulging.

[0101] Another embodiment of the present invention also provides a battery structure, such as Figure 9 As shown, Figure 9 The diagram shown is a schematic diagram of a battery structure in one embodiment of the present invention. The battery structure includes a battery under test M21, a terminal device M22, and a patch-type battery bulging monitoring device M23.

[0102] In this embodiment, the battery under test M21 can be various types of rechargeable batteries, such as lithium-ion batteries, nickel-metal hydride batteries, etc., depending on the energy requirements and design requirements of the terminal device M22. The patch-type battery bulging monitoring device M23 can be directly attached to the surface of the battery under test M21 to monitor the battery bulging in real time.

[0103] Specifically, the terminal device M22 is communicatively connected to the electrical lead-out structure.

[0104] The terminal device M22 includes, such as a cell phone terminal, a notebook computer terminal or a smart watch terminal, so as to realize interaction with a radio frequency signal. In the embodiment, the terminal device M22 is an object served by a battery structure, and can be any electronic product, such as a smart phone, a tablet computer, a notebook computer and a wearable device, which needs to be powered by a battery.

[0105] The above-described embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for detecting battery bulging, applied to a patch-type battery bulging detection device, characterized in that, The device comprises a flexible substrate, a passive wireless acoustic surface wave sensor and an electrical lead-out structure. One side of the flexible substrate is used to attach to the surface of the metal shell of the battery to be measured. The other side of the flexible substrate is closely attached to the passive wireless acoustic surface wave sensor. The electrical lead-out structure is arranged on the side of the passive wireless acoustic surface wave sensor away from the flexible substrate, and is used to feed back the monitoring result of the passive wireless acoustic surface wave sensor to the outside world. The method comprises: Respectively monitoring and outputting deformation data reflecting the deformation degree of the battery to be measured, wherein the deformation data comprises propagation speed and wavelength. Based on a preset frequency calculation formula, the propagation speed and the wavelength are processed to obtain sensor resonance frequency data. According to the linear relationship among resonance frequency, bending angle and bending strain, the resonance frequency data is processed to obtain real-time bending angle value and real-time bending strain value of the battery to be measured respectively; an equivalent elliptical model of the bulge of the battery to be measured is constructed according to the resonance frequency data; the real-time bending angle value is calculated according to the equivalent elliptical model; the bending curvature in the equivalent elliptical model is calculated according to the real-time bending angle value, and the real-time bending strain value is calculated based on the beam bending theory. Based on the real-time bending angle value and the real-time bending strain value, the monitoring result reflecting the bulge degree of the battery to be measured is generated correspondingly.

2. The battery bulge monitoring method of claim 1, wherein, The frequency calculation formula is represented by the following expression: The monitoring result reflecting the bulge degree of the battery to be measured is generated correspondingly based on the bending angle value and the bending strain value, which comprises: wherein, is the propagation speed, is the wavelength, is the resonance frequency.

3. The method of claim 1, wherein, If the bending angle value and the bending strain value are both within the preset safe interval, monitoring information with battery charging strategy adjustment is generated; If the bending angle value and the bending strain value are both within the preset non-safe interval, monitoring information with battery replacement reminder is generated. The flexible substrate is a bendable flexible material.

4. The method of claim 1, wherein, The electrical lead-out structure is connected with a patch antenna.

5. The method of claim 1, wherein, The passive wireless acoustic surface wave sensor is prepared through photolithography and stripping process.

6. The method of claim 1, wherein, ​

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