A magnetoelectric composite material, preparation method and sensor

Abstract

The present invention relates to the technical field of battery status monitoring, and in particular to a magnetoelectric composite material, a preparation method and a sensor. The magnetoelectric composite material involved in the present invention comprises a stacked ferroelectric material layer and a substrate layer; the ferroelectric material layer comprises a blended PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) copolymer and composite magnetic particles, and the material of the composite magnetic particles comprises one, two or more of ferroferric oxide magnetic powder, iron cobalt vanadium magnetic powder and cobalt ferrite magnetic powder; the substrate layer comprises a flexible circuit board and a glass substrate, and the flexible circuit board is fixed on the glass substrate. The present invention solves the technical problems that traditional battery status monitoring sensors cannot realize directional monitoring of multiple parameters, and that sensors that can realize multi-parameter monitoring are large in size, expensive and have low monitoring sensitivity. The magnetoelectric composite material preparation method and sensor of the present invention have the same beneficial effects as the magnetoelectric composite material.

Description

Technical field

[0001] The present invention relates to the technical field of battery status monitoring, and in particular to a magnetoelectric composite material, a preparation method and a sensor. [Background Technology]

[0002] Traditional battery status monitoring sensors are generally used to monitor and provide early warning of thermal runaway risks. These sensors are mainly divided into direct and indirect battery status monitoring sensors. Indirect battery status monitoring sensors only monitor the battery's discharge and charging processes, analyzing the battery's capacity and health to determine the battery's status. However, they cannot quickly and accurately determine the battery's status.

[0003] Compared with indirect battery status monitoring sensors, direct battery status monitoring sensors can generally determine the battery status by directly measuring battery parameters such as voltage, current and temperature. Traditional sensors can only perform directional monitoring of one parameter (for example, traditional current sensors can only monitor the current parameter), and cannot achieve integrated monitoring of multiple parameters. Sensors that can monitor two or more parameters are mostly composed of several independent sensors stacked or integrated together, which are large in size and high in cost. During the monitoring process, the sensitivity of monitoring parameters such as current, temperature, and pressure is low, making it difficult to perform high-sensitivity multi-parameter monitoring of the battery status. [Summary of the invention]

[0004] In order to solve the technical problems that traditional battery status monitoring sensors cannot achieve directional monitoring of multiple parameters, and that sensors that can achieve multi-parameter monitoring are large in size, high in cost, and have low monitoring sensitivity, the present invention provides a magnetoelectric composite material, a preparation method and a sensor.

[0005] The technical solution of the present invention to solve the technical problem is to provide a magnetoelectric composite material, comprising a ferroelectric material layer and a substrate layer stacked;

[0006] The ferroelectric material layer includes a blended PVD F-HFP (polyvinylidene fluoride-hexafluoropropylene) copolymer and composite magnetic particles, wherein the material of the composite magnetic particles includes one, two or more of ferroferric oxide magnetic powder, iron cobalt vanadium magnetic powder and cobalt ferrite magnetic powder;

[0007] The substrate layer includes a flexible circuit board and a glass substrate, and the flexible circuit board is fixed on the glass substrate.

[0008] Preferably, the composite magnetic particles are FeCoV (iron-cobalt-vanadium alloy) magnetic nanoparticles.

[0009] Preferably, the thickness of the magnetoelectric composite material is 10 μm-40 μm.

[0010] Another technical solution of the present invention to solve the above technical problems is to provide a method for preparing a magnetoelectric composite material, which is used to obtain the above magnetoelectric composite material. The preparation method comprises:

[0011] Providing an organic solvent and PVD FH FP powder, dissolving the PVD FH FP powder in the organic solvent to obtain an initial solution, wherein the molar ratio of HFP to PVDF in the PVD FH FP powder ranges from 1:4 to 1:2, and the mass ratio of the PVD FH FP powder to the organic solvent is 1:10;

[0012] adding the composite magnetic particles to the initial solution and stirring to obtain a mixed solution, wherein the mass of the added PVD FH FP powder is 5 to 10 times the mass of the composite magnetic particles;

[0013] forming the ferroelectric material layer on the surface of the substrate layer with the mixed solution to obtain a first composite material;

[0014] The first composite material is pretreated to obtain a second composite material, where the second composite material is the magnetoelectric composite material.

[0015] Preferably, the pretreatment comprises the following steps:

[0016] performing a vacuum drying process on the first composite material to evaporate the organic solvent in the first composite material;

[0017] performing an annealing treatment on the first composite material after vacuum drying, so that the ferroelectric material layer is crystallized and formed on the surface of the substrate layer;

[0018] The annealed first composite material is subjected to in-situ polarization treatment to obtain the second composite material.

[0019] Preferably, in the vacuum drying process, the time for evaporating the organic solvent is 10 min to 15 min; in the annealing process, the annealing temperature is 130° C. to 150° C., and the annealing time is 60 min to 90 min.

[0020] Preferably, in the in-situ polarization treatment, the polarization temperature is 25° C. to 35° C., the polarization voltage is 25 kV to 30 kV, and the polarization time is 5 min to 15 min.

[0021] Preferably, the stirring process comprises the following steps:

[0022] Performing a first stirring at a rotation speed of 200 rpm to 400 rpm for 6 to 8 hours to obtain the mixed solution;

[0023] After the first stirring is completed, the mixed solution is stirred for a second time at a rotation speed of 100 r / min to 150 r / min and a duration of 1 h to 2 h to remove bubbles in the mixed solution.

[0024] Another technical solution of the present invention to solve the above technical problems is to provide a sensor, including an electrode layer and a magnetoelectric composite material obtained by the above-mentioned magnetoelectric composite material preparation method, wherein the magnetoelectric composite material is electrically connected to the electrode layer; the ferroelectric material layer is stacked between the substrate layer and the electrode layer.

[0025] Preferably, the sensor further comprises a protective layer, wherein the protective layer is connected to a side of the electrode layer facing away from the ferroelectric material layer, and the thickness of the protective layer is 10 μm-30 μm.

[0026] Compared with the prior art, the magnetoelectric composite material, preparation method and sensor provided by the present invention have the following advantages:

[0027] 1. A first embodiment of the present invention provides a magnetoelectric composite material, comprising a stacked ferroelectric material layer and a substrate layer; the ferroelectric material layer comprises a blended PVD F-HFP (polyvinylidene fluoride-hexafluoropropylene) copolymer and composite magnetic particles, the material of the composite magnetic particles comprising one, two or more of ferroferric oxide magnetic powder, iron cobalt vanadium magnetic powder and cobalt ferrite magnetic powder; the substrate layer comprises a flexible circuit board and a glass substrate, and the flexible circuit board is fixed on the glass substrate.

[0028] Understandably, sensors made from PVDF (polyvinylidene fluoride) can generate induced charges through changes in spontaneous polarization intensity to detect changes in external temperature and pressure. PVDF-HFP has a similar crystalline structure to PVDF. By introducing HFP (hexafluoropropylene) segments into the VDF (vinylidene fluoride) backbone, the content of CF dipoles and the steric hindrance effect are relatively increased, thereby improving the orientation of the CF dipoles and the content of β-phase crystals, thereby enhancing piezoelectric and pyroelectric properties.

[0029] It should be noted that the composite magnetic particles bring magnetostriction to the ferroelectric material layer. The magnetostriction phenomenon can convert magnetoelectric signals into force signals, so that the magnetoelectric composite material has the ability to sense magnetoelectric signals, and then can monitor parameters such as current, temperature, and pressure through a single independent sensor; the magnetizing field intensity required by the composite magnetic particles is not high, and is suitable for magnetostrictive materials that improve current signal monitoring for sensors.

[0030] 2. In the magnetoelectric composite material provided by the first embodiment of the present invention, the composite magnetic particles are FeCoV (iron-cobalt-vanadium alloy) magnetic nanoparticles.

[0031] It can be understood that the particle size of FeCoV magnetic nanoparticles is uniform, and the magnetostriction curve of FeCoV magnetic nanoparticles is consistent with the current response curve of existing sensors and has the same linear region. Therefore, FeCoV magnetic nanoparticles are suitable as magnetostrictive materials for high-sensitivity sensors, and have good magnetostrictive properties, high magnetic sensitivity, low iron loss and other advantages.

[0032] It should be noted that the magnetic nanoparticles using FeCoV have a higher Curie temperature and better heat resistance; the Curie temperature refers to the temperature at which the spontaneous magnetization intensity in a magnetic material drops to zero, and is used to describe the critical temperature at which a material loses its magnetism at a specific temperature.

[0033] 3. The magnetoelectric composite material provided in the first embodiment of the present invention has a thickness of 10 μm-40 μm.

[0034] It can be understood that when the magnetoelectric composite material is in the thickness range of 10μm-40μm, the piezoelectric coefficient, pyroelectric coefficient and magnetostriction coefficient of the ferroelectric material layer are high, and it is sensitive to changes in parameters such as current, temperature, and pressure, thereby improving the monitoring sensitivity of the sensor made of the magnetoelectric composite material.

[0035] 4. A second embodiment of the present invention provides a method for preparing a magnetoelectric composite material, which is used to obtain the above-mentioned magnetoelectric composite material. The preparation method includes: providing an organic solvent and PVD FH FP powder, dissolving PVD F-HFP powder in the organic solvent to obtain an initial solution, wherein the molar ratio of HFP to PVDF in the PVD FH FP powder ranges from 1:4 to 1:2, and the mass ratio of PVD FH FP powder to the organic solvent is 1:10; adding composite magnetic particles to the initial solution and stirring to obtain a mixed solution, wherein the mass of the added PVD F-HFP powder is 5 to 10 times the mass of the composite magnetic particles; forming a ferroelectric material layer on the surface of the substrate layer with the mixed solution to obtain a first composite material; and pretreating the first composite material to obtain a second composite material, which is a magnetoelectric composite material.

[0036] As can be understood, the method for preparing the magnetoelectric composite material provided in the second embodiment of the present invention first dissolves PVDF-HFP powder in an organic solvent to form an initial solution, then dopes the composite magnetic particles into the initial solution and stirs it to form a uniform mixed solution. This stirring process ensures a fully uniform mixing of the mixed solution, preventing agglomeration and magnetic powder sedimentation. By adjusting parameters such as the stirring speed and duration, it is also possible to eliminate excess bubbles in the solution caused by the blending system.

[0037] It should be noted that the substrate layer includes a flexible circuit board and a glass substrate secured together by transparent tape. The glass substrate is vacuum-adsorbed by a coating machine, with the flexible circuit board on top and the glass substrate on the bottom. The glass substrate facilitates the next coating step. Furthermore, after obtaining a mixed solution, the mixed solution is slit-coated onto the flexible circuit board in the substrate layer to form a first composite material. The second composite material, obtained after pre-treating the first composite material, is a magnetoelectric composite material. This composite material is compact, flexible, and has high pyroelectric, piezoelectric, and magnetostrictive coefficients. It can monitor changes in parameters such as current, temperature, and pressure, thereby determining the battery status.

[0038] The preparation method provided in the second embodiment of the present invention solves the technical problems that traditional battery status monitoring sensors cannot realize directional monitoring of multiple parameters, and sensors that can realize multi-parameter monitoring are large in size, high in cost and have low monitoring sensitivity.

[0039] 5. The preparation method of the magnetoelectric composite material provided in the second embodiment of the present invention comprises the following steps of pretreatment: vacuum drying the first composite material to evaporate the organic solvent in the first composite material; annealing the vacuum dried first composite material to allow the ferroelectric material layer to crystallize and form on the surface of the substrate layer; and in-situ polarization treatment of the annealed first composite material to obtain a second composite material.

[0040] It can be understood that the magnetoelectric composite material obtained through vacuum drying, annealing and in-situ polarization treatment has the characteristics of small size, flexibility, high pyroelectric coefficient, high piezoelectric coefficient and high magnetostriction coefficient, which improves the sensitivity of monitoring parameters such as current, temperature and pressure.

[0041] It should be noted that the second composite material is the magnetoelectric composite material mentioned above, wherein the vacuum drying treatment can fully evaporate the organic solvent in the first composite material to avoid the generation of bubbles on the magnetoelectric composite material obtained after annealing and in-situ polarization treatment.

[0042] Annealing the first composite material after vacuum drying can reduce the residual stress of the magnetoelectric composite material, stabilize the size of the magnetoelectric composite material, and reduce its tendency to deform and crack; in addition, annealing can also refine the grains and enhance the ductility of the magnetoelectric composite material.

[0043] The second embodiment of the present invention can improve the mechanical properties, piezoelectric properties and pyroelectric properties of the magnetoelectric composite material by vacuum drying and annealing the first composite material, thereby improving the flexibility of the magnetoelectric composite material and the sensitivity of using the magnetoelectric composite material to detect temperature and pressure.

[0044] 6. In the preparation method of the magnetoelectric composite material provided in the second embodiment of the present invention, in the vacuum drying process, the time for evaporating the organic solvent is 10 minutes to 15 minutes; in the annealing process, the annealing temperature is 130°C to 150°C, and the annealing time is 60 minutes to 90 minutes.

[0045] It can be understood that the vacuum drying process is to evaporate the organic solvent in a vacuum drying oven. After the evaporation is completed, the first composite material is annealed. The annealing process is to crystallize the ferroelectric material layer on the surface of the substrate layer.

[0046] It should be noted that the above-mentioned evaporation time, annealing time and optimal annealing temperature range can ensure that the surface of the ferroelectric material layer is uniform and flat when it crystallizes, without cracks or potholes, thereby improving the monitoring sensitivity of the magnetoelectric composite material to parameters such as current, temperature, and pressure.

[0047] 7. In the preparation method of the magnetoelectric composite material provided in the second embodiment of the present invention, in the in-situ polarization treatment, the polarization temperature is 25° C. to 35° C., the polarization voltage is 25 kV to 30 kV, and the polarization time is 5 min to 15 min.

[0048] It can be understood that through in-situ polarization treatment, the crystal structure of the β-phase crystals in the magnetoelectric composite material can be enhanced, so that the CF dipoles in the magnetoelectric composite material produce preferential orientation, the piezoelectric coefficient and pyroelectric coefficient of the magnetoelectric composite material are increased, and the monitoring sensitivity of the sensor made of the magnetoelectric composite material to temperature and pressure is improved.

[0049] It should be noted that the first composite material that has completed the vacuum drying process is subjected to annealing treatment and in-situ polarization treatment to finally obtain the second composite material, ie the above-mentioned magnetoelectric composite material.

[0050] 8. The preparation method of the magnetoelectric composite material provided in the second embodiment of the present invention, the stirring treatment includes the following steps: performing a first stirring at a rotation speed of 200r / min to 400r / min and a duration of 6h to 8h to obtain a mixed solution; after the first stirring is completed, the mixed solution is stirred for a second time at a rotation speed of 100r / min to 150r / min and a duration of 1h to 2h to remove bubbles in the mixed solution.

[0051] It can be understood that the mixed solution is obtained by the first stirring, and the stirring time is at least 6 hours to ensure that the mixed solution is stirred evenly, and the mixed solution includes PVD F-HFP copolymer and composite magnetic particles; the second stirring is carried out after the first stirring is completed and the mixed solution is obtained. The second stirring can remove the bubbles in the mixed solution, so that the mixed solution has a uniform texture and no cavities are generated due to the presence of bubbles.

[0052] The rotation speed of the second stirring is lower than that of the first stirring. The bubbles generated by the first high-speed stirring of the mixed solution can be removed by the second low-speed stirring.

[0053] The mixed solution obtained after two stirrings can enable the magnetoelectric composite material finally prepared to obtain higher piezoelectric coefficient, pyroelectric coefficient and magnetostriction coefficient.

[0054] It should be noted that both stirring methods are mechanical stirring, wherein mechanical stirring is to mix and stir by driving a stirring device through a motor and a transmission device, which is suitable for batch production of large-volume mixing and stirring, is simple and convenient to operate, and does not require special stirring devices.

[0055] 9. The third embodiment of the present invention provides a sensor, comprising an electrode layer and a magnetoelectric composite material obtained by the above-mentioned magnetoelectric composite material preparation method, wherein the magnetoelectric composite material is electrically connected to the electrode layer; and a ferroelectric material layer is stacked between the substrate layer and the electrode layer.

[0056] It can be understood that the sensor includes an electrically connected magnetoelectric composite material and an electrode layer. Since the magnetoelectric composite material has pyroelectric, piezoelectric and magnetostrictive properties, the charge changes caused by changes in current, temperature and pressure are converted into electrical signals. The electrode layer can receive the electrical signals generated in the magnetoelectric composite material. Through this design, the sensor can realize real-time monitoring of multiple parameters, ensure high sensitivity of monitoring, and ensure the reliability and accuracy of the monitoring results.

[0057] In addition, the electrode layer can also be connected to external devices to transmit electrical signals to an external control system, which then performs operations such as classification and storage of the electrical signals and threshold warning.

[0058] It should be noted that the electrode layer is specifically formed by printing electrodes on the magnetoelectric composite material. Through this design, when the parameters such as induced current, temperature, and pressure of the magnetoelectric composite material change, the charge changes generated on the ferroelectric material layer can be transmitted through the electrode layer.

[0059] 10. The sensor provided in the third embodiment of the present invention further includes a protective layer connected to a side of the electrode layer facing away from the ferroelectric material layer. The thickness of the protective layer is 10 μm-30 μm.

[0060] It can be understood that providing a protective layer with a thickness of 10 μm-30 μm can effectively prevent foreign substances such as dust, stains and oil stains from entering the interior of the sensor, thereby preventing these substances from causing damage to signal collection and transmission.

[0061] It should be noted that the connection between the protective layer and the electrode layer is specifically achieved by coating the protective layer on the side of the electrode layer facing away from the ferroelectric material layer and then drying it. This makes the sensor scratch-resistant and drop-resistant due to the presence of the protective layer, and its wear resistance is increased, thereby greatly extending the service life of the sensor.

Brief Description of the Drawings

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0063] Figure 1 Schematic diagram of a magnetoelectric composite material provided by the first embodiment of the present invention.

[0064] Figure 2 It is a schematic flow chart of a method for preparing a magnetoelectric composite material provided by the second embodiment of the present invention.

[0065] Figure 3 4 is a schematic flow chart of the pretreatment in step S4 of a method for preparing a magnetoelectric composite material provided by the second embodiment of the present invention.

[0066] Figure 4 It is a schematic flow chart of the stirring process in step S2 of a method for preparing a magnetoelectric composite material provided by the second embodiment of the present invention.

[0067] Figure 5 is a schematic diagram of a sensor provided by the third embodiment of the present invention.

[0068] Description of the accompanying drawings:

[0069] 1. Magnetoelectric composite material; 11. Ferroelectric material layer; 12. Substrate layer; 121. Flexible circuit board; 122. Glass substrate;

[0070] 2. Sensor; 21. Electrode layer; 22. Protective layer. [Specific implementation method]

[0071] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0072] In the embodiments provided herein, it should be understood that "B corresponding to A" means that B is associated with A and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B based solely on A; B can also be determined based on A and / or other information.

[0073] It should be understood that references to "one embodiment" or "an embodiment" throughout this specification mean that specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present invention. Therefore, the appearance of "in one embodiment" or "in an embodiment" throughout this specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Those skilled in the art should also be aware that the embodiments described in this specification are all optional embodiments, and the actions and modules involved are not necessarily required for the present invention.

[0074] In various embodiments of the present invention, it should be understood that the size of the serial numbers of the above-mentioned processes does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0075] The flow charts and block diagrams in the accompanying drawings of the present invention illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a module, program segment or a part of code, and the module, program segment or a part of code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementation schemes, the functions marked in the box can also occur in a different order than those marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which is determined based on the functions involved. It should be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented by a dedicated hardware-based system that performs the specified function or operation, or can be implemented by a combination of dedicated hardware and computer instructions.

[0076] Battery status monitoring sensors are generally used to monitor and warn of early risks of thermal runaway. When the thermal runaway process is in the early stages, abnormal physical or chemical reactions generally begin to occur inside the battery, causing the temperature of local areas inside the battery to rise. Over time, this temperature will spread and propagate, causing the temperature of a larger area inside the battery to rise.

[0077] There are many reasons for the occurrence of early thermal runaway, such as external factors (such as overcharging and discharging, damage to the outside of the battery, etc.) or potential defects inside the battery (such as material defects). Therefore, sensors are used to directly measure battery parameters such as voltage, current, and temperature to determine the battery status and provide early warning for thermal runaway.

[0078] The technical solutions involved in the present invention are described below.

[0079] See also Figure 1 , a first embodiment of the present invention provides a magnetoelectric composite material 1, comprising a ferroelectric material layer 11 and a substrate layer 12 stacked;

[0080] The ferroelectric material layer 11 includes a blended PVD FH FP (polyvinylidene fluoride-hexafluoropropylene) copolymer and composite magnetic particles, wherein the material of the composite magnetic particles includes one, two or more of ferroferric oxide magnetic powder, iron cobalt vanadium magnetic powder and cobalt ferrite magnetic powder;

[0081] The substrate layer 12 includes a flexible circuit board 121 and a glass substrate 122 , and the flexible circuit board 121 is fixed on the glass substrate 122 .

[0082] As can be understood, PVD FH FP is a piezoelectric material with excellent piezoelectric properties. Compared to traditional ceramic piezoelectric materials, it offers advantages such as a high piezoelectric coefficient, good biocompatibility, a wide frequency response, high flexibility, and easy processing. PVD FH FP can also form a variety of different crystal structures, the most common being α, β, and γ phases. Among them, the β-phase PVD F-HFP, with its polar crystal structure, exhibits stronger piezoelectric properties. Therefore, the key to improving the piezoelectric performance of PVD FH FP lies in increasing the β-phase crystal content.

[0083] PVDF (polyvinylidene fluoride) is a common piezoelectric material. Sensors made with PVDF can generate induced charges through changes in spontaneous polarization intensity to detect changes in external temperature and pressure. However, the chemical structures of PVDF-HFP and PVDF differ. PVDF is a linear polymer with only one fluorine atom bonded to a carbon atom in its molecular chain. PVDF-HFP, on the other hand, is based on PVDF but introduces fluorine atoms into the polymer chain through reaction with hydrofluoric acid, thereby forming a hydrogen bond network structure.

[0084] It should be noted that because PVD FH FP contains more fluorine atoms, its physical properties differ from those of PVDF. For example, PVD FH FP has better heat resistance than PVDF and can withstand temperatures up to 200°C. PVD F-H FP also has better chemical resistance and mechanical properties.

[0085] The PVD F-HFP copolymer used in the present invention has a similar crystal structure to PVDF. Specifically, the PVD F-HFP copolymer introduces HFP (hexafluoropropylene) chain segments into the VDF (vinylidene fluoride) skeleton, and the CF dipole content and steric hindrance effect are relatively increased, thereby improving the orientation of the CF dipole and the content of β-phase crystals to enhance the piezoelectric and pyroelectric properties.

[0086] Furthermore, in the process of preparing the magnetoelectric composite material 1, the technical solution of the first embodiment of the present invention requires in-situ polarization treatment of the intermediate product. The in-situ polarization can also increase the crystal structure of the β-phase crystal and cause its polymer chain to have preferential orientation. The carbon-fluorine bond of the magnetoelectric composite material 1 obtained by in-situ polarization has strong polarity and is more stable.

[0087] In particular, the β phase is a crystal structure, which refers to the crystalline state of a substance formed under certain conditions; the β crystal form is a type of crystal structure. Due to its polarity, the β crystal form gives PVDF-based materials powerful piezoelectric and ferroelectric effects, and is widely used in piezoelectric materials such as sensors, transducers, nanogenerators, etc., and has become one of the most widely used piezoelectric polymer materials.

[0088] The CF dipole can be understood as a carbon-fluorine (CF) single bond. Steric hindrance refers to the steric hindrance caused by the proximity of certain atoms or groups in a molecule. Preferred orientation of polymer chains occurs when, under the influence of an external force, molecular chains or other structural units preferentially align along the direction of the force.

[0089] It should be noted that the ferroelectricity of PVDF-based materials originates from their crystal structure. As a semi-crystalline polymer, PVDF-based materials have a complex crystal structure and crystalline phases (usually α, β, and γ). The in-situ poling process can promote the transformation of α-phase crystals in the PVD FH FP into β-phase crystals, further improving the piezoelectric and pyroelectric properties of the magnetoelectric composite material 1.

[0090] Conventional corona poling achieves polarization by generating a strong electric field at the tip of a tungsten wire to induce the orientation of the CF dipoles within the piezoelectric material. However, due to the limited area of ​​the tungsten tip, the polarization voltage must exceed 18,000 V and the polarization time must exceed 60 minutes, resulting in low efficiency and difficulty in producing large-area ferroelectric films with uniform polarization.

[0091] To solve this bottleneck, the present invention adopts a polarization device with an in-situ surface gate polarization process to perform in-situ polarization on the intermediate product (hereinafter referred to as the sample) in the preparation process of the magnetoelectric composite material 1. The device includes an electrode plate, a source, a gate, a tray metal plate and a rotating substrate.

[0092] The source and gate electrodes move over the sample, with a 7.5kV voltage applied to the source electrode to generate electronegative cations. These cations are then accelerated by a 3.0kV gate voltage and uniformly deposited on the sample's surface. A large electric field is formed between the electronegative cations and the bottom electrode, achieving effective polarization. The rotating substrate can rotate 360°, slowly rotating during the polarization process to ensure uniform polarization of every area of ​​the sample. This device shortens the polarization process, simplifies the polarization conditions, significantly reduces the polarization voltage, and improves polarization efficiency.

[0093] It should be noted that the composite magnetic particles bring magnetostriction to the ferroelectric material layer 11. The magnetostriction phenomenon means that when ferromagnetic crystals and ferrimagnetic crystals are magnetized in an external magnetic field, parameters such as length and volume will undergo slight changes. After the external magnetic field is removed, they will return to their original length or volume.

[0094] In the technical solution of the present invention, the magnetostrictive phenomenon can convert magnetoelectric signals into force signals, so that the magnetoelectric composite material 1 has the ability to sense magnetoelectric signals. As a result, the magnetoelectric composite material 1 has the ability to monitor current, temperature, and pressure at the same time, and can monitor parameters such as current, temperature, and pressure through a single independent sensor.

[0095] It can be understood that the PVD FH FP (polyvinylidene fluoride-hexafluoropropylene) copolymer and the composite magnetic particles in the ferroelectric material layer 11 are in a blended relationship. Since the composite magnetic particles can bring magnetostriction to the ferroelectric material layer 11, it is necessary to dope the composite magnetic particles into the PVD FH FP copolymer to increase the magnetostrictive properties of the magnetoelectric composite material 1, thereby realizing the monitoring of magnetoelectric signals; further, as a preferred implementation method in the first embodiment of the present invention, in the ferroelectric material layer 11, the composite magnetic particles are uniformly distributed in the PVD FH FP copolymer.

[0096] The substrate layer 12 includes a flexible circuit board 121 and a glass substrate 122 . The flexible circuit board 121 is fixed on the glass substrate 122 . The flexible circuit board 121 and the glass substrate 122 are fixed together by a transparent tape. The glass substrate 122 is vacuum-adsorbed by a coating machine.

[0097] Coating machines are mainly used for surface coating production of films, paper, etc. Specifically, they coat the rolled substrate with a layer of glue, paint or ink with specific functions, and then cut it into sheets or roll it up after drying.

[0098] It should be noted that the principle of the magnetoelectric composite material 1 inducing current, temperature, and pressure is as follows: the current will first form a magnetic field around the magnetoelectric composite material 1. After inducing the magnetic field, the composite magnetic particles will undergo magnetostriction effect and deform, and then be transmitted to the magnetoelectric composite material 1. After receiving the deformation pressure, the magnetoelectric composite material 1 will undergo piezoelectric effect, output voltage, generate an electric field, and then generate a potential difference between the upper and lower surfaces of the magnetoelectric composite material 1, thereby realizing the conversion of magnetic signals and electrical signals.

[0099] At the same time, when the external temperature changes and produces thermal changes, the magnetoelectric composite material 1 generates a pyroelectric effect after receiving the temperature change signal, outputs voltage, generates an electric field, and generates a potential difference between the upper and lower surfaces of the magnetoelectric composite material 1, realizing the conversion of thermal signals and electrical signals.

[0100] When external pressure changes and deformation occurs, the magnetoelectric composite material 1 receives the deformation pressure and produces a piezoelectric effect, outputs voltage, generates an electric field, and generates a potential difference between the upper and lower surfaces of the magnetoelectric composite material 1, thereby realizing the conversion of mechanical signals and electrical signals.

[0101] As a preferred implementation of the first embodiment of the present invention, the composite magnetic particles are FeCoV (iron-cobalt-vanadium alloy) magnetic nanoparticles.

[0102] It can be understood that the particle size of FeCoV magnetic nanoparticles is uniform, and the magnetostriction curve of FeCoV magnetic nanoparticles is consistent with the current response curve of existing sensors and has the same linear region. Therefore, FeCoV magnetic nanoparticles are suitable as magnetostrictive materials for high-sensitivity sensors, and have good magnetostrictive properties, high magnetic sensitivity, and bottom iron loss.

[0103] Furthermore, the composite magnetic particles require a low magnetizing field strength, and are suitable for use as magnetostrictive materials for improving current signal monitoring in sensors.

[0104] It should be noted that the magnetic nanoparticles using FeCoV have a higher Curie temperature and better heat resistance; the Curie temperature refers to the temperature at which the spontaneous magnetization intensity in a magnetic material drops to zero, and is used to describe the critical temperature at which a material loses its magnetism at a specific temperature.

[0105] Specifically, above the Curie temperature, the material will maintain magnetism, while below the Curie temperature, the material will lose magnetism. Different materials have different Curie temperatures. For example, the Curie temperature of iron is about 800°C, while the Curie temperature of nickel is lower, about 631°C.

[0106] Furthermore, the thickness of the magnetoelectric composite material 1 is 10 μm-40 μm.

[0107] It can be understood that when the magnetoelectric composite material 1 is in the thickness range of 10μm-40μm, the piezoelectric coefficient, pyroelectric coefficient and magnetostriction coefficient of the ferroelectric material layer 11 are relatively high, and it is sensitive to changes in parameters such as current, temperature, and pressure, thereby improving the monitoring sensitivity of the sensor made of the magnetoelectric composite material 1.

[0108] It should be noted that the thickness of the magnetoelectric composite material 1 can be 10 μm, 20 μm, 30 μm or 40 μm; it can be understood that the thickness of the magnetoelectric composite material 1 is not limited to the above-mentioned specific values. Experimental comparison has shown that when the thickness of the magnetoelectric composite material 1 is 20 μm, its piezoelectric coefficient and pyroelectric coefficient are the highest.

[0109] In addition, since the thickness range of the magnetoelectric composite material 1 spans a large range, its thickness can be designed according to actual needs when preparing the magnetoelectric composite material 1. For example, in the battery status monitoring sensor used in this field, the thickness of the magnetoelectric composite material 1 can be set according to the internal gap size of the battery pack.

[0110] See also Figure 2 A second embodiment of the present invention provides a method for preparing a magnetoelectric composite material, for obtaining the above-mentioned magnetoelectric composite material, the preparation method comprising:

[0111] S1: providing an organic solvent and PVD FH FP powder, dissolving the PVD F-HF P powder in the organic solvent to obtain an initial solution, wherein the molar ratio of HFP to PVDF in the PVD FH FP powder ranges from 1:4 to 1:2, and the mass ratio of the PVD F-HF P powder to the organic solvent is 1:10;

[0112] S2: adding composite magnetic particles to the initial solution and stirring to obtain a mixed solution, wherein the mass of the added PV D FH FP powder is 5 to 10 times the mass of the composite magnetic particles;

[0113] S3: forming a ferroelectric material layer on the surface of the substrate layer with the mixed solution to obtain a first composite material;

[0114] S4: pre-treating the first composite material to obtain a second composite material, where the second composite material is a magnetoelectric composite material.

[0115] It can be understood that the preparation method of the magnetoelectric composite material provided in the second embodiment of the present invention first dissolves PV DF-H FP powder in an organic solvent to form an initial solution, and then dopes the composite magnetic particles into the initial solution and stirs it to form a uniform mixed solution.

[0116] In step S1, the molar ratio of HFP to PVDF in the PVD FH FP powder is 1:4 to 1:2, wherein the molar ratio of HFP to PVDF is any ratio between 1:4 and 1:2.

[0117] For example, when synthesizing 1 mol of PVDF-HFP polymer, when the molar ratio of HFP to PVDF is 1:4, that is, the amount of HFP used is 0.2 mol and the amount of PVDF used is 0.8 mol.

[0118] Specifically, different molar ratios of HFP and PVDF will lead to changes in the properties of the magnetoelectric composite material. The present invention adopts an in-situ polarization preparation method. As a preferred implementation scheme in the second embodiment, the molar ratio of HFP to PVDF is 1:4.

[0119] The organic solvent used in step S1 is mainly used to dissolve the PVD FH FP powder, and the organic solvent needs to be easily volatile. It is understood that the type of organic solvent used depends on the specific composition and molecular weight of the PVD FH FP. The organic solvent used in the second embodiment of the present invention is butanone.

[0120] In addition, the organic solvents that can be used in this embodiment may also include acetone, tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), etc. These organic solvents can dissolve the PVD FH FP powder and make it into a solution state.

[0121] In step S2, the mass of the added composite magnetic particles is 5 to 10 times that of the PVD FH FP powder, that is, the mass of the PVD F-HFP powder is 10%-20% of the mass of the composite magnetic particles. The stirring process can ensure that the mixed solution is fully and evenly mixed without agglomeration and magnetic powder deposition. By setting parameters such as the stirring speed and duration, excess bubbles generated in the solution by the blending system can also be eliminated.

[0122] It should be noted that the substrate layer includes a flexible circuit board and a glass substrate fixed together by transparent tape. The glass substrate is vacuum-adsorbed by a coating machine, where the flexible circuit board is on the top and the glass substrate is on the bottom. The role of the glass substrate is to facilitate the next step of coating.

[0123] Furthermore, in step S3, after obtaining the mixed solution, the mixed solution is slit-coated on the flexible circuit board of the substrate layer to form a first composite material. The second composite material obtained after pre-treating the first composite material, namely the magnetoelectric composite material, has the characteristics of small size, flexibility, high pyroelectric coefficient, high piezoelectric coefficient, and high magnetostriction coefficient. It can monitor changes in parameters such as current, temperature, and pressure, and the monitoring sensitivity is greatly improved, thereby being able to judge the battery status.

[0124] As an optional implementation method, a slit coating method is used to coat the mixed solution on the flexible circuit board. By adjusting the scraper coating speed, the mixed solution can be scraped more evenly on the substrate layer. Compared with spin coating, spraying and other methods, scraping is less likely to produce bubbles, and the final magnetoelectric composite material has better flatness.

[0125] The preparation method provided in the second embodiment of the present invention solves the technical problems that traditional battery status monitoring sensors cannot realize directional monitoring of multiple parameters, and sensors that can realize multi-parameter monitoring are large in size, high in cost and have low monitoring sensitivity.

[0126] For details, please refer to Figure 3 , the preprocessing includes the following steps:

[0127] S41: performing a vacuum drying process on the first composite material to evaporate the organic solvent in the first composite material;

[0128] S42: performing annealing treatment on the first composite material after vacuum drying to allow the ferroelectric material layer to crystallize and form on the surface of the substrate layer;

[0129] S43: performing in-situ polarization treatment on the annealed first composite material to obtain a second composite material.

[0130] It can be understood that after the vacuum drying, annealing and in-situ polarization treatment of steps S 41 to S 43, the obtained magnetoelectric composite material has the characteristics of small size, flexibility, high pyroelectric coefficient, high piezoelectric coefficient and high magnetostriction coefficient. The above pretreatment can improve the sensitivity of monitoring parameters such as current, temperature and pressure.

[0131] It should be noted that the second composite material is the magnetoelectric composite material mentioned above, wherein, in step S41, the vacuum drying treatment is carried out in a vacuum drying oven to fully evaporate the organic solvent in the first composite material to avoid the formation of bubbles on the magnetoelectric composite material obtained after annealing and in-situ polarization treatment.

[0132] In step S42, the first composite material after vacuum drying is annealed, which can reduce the residual stress of the magnetoelectric composite material, stabilize the size of the magnetoelectric composite material, eliminate the defects inside it, and reduce its tendency to deform and crack, making it more uniform as a whole. It can also refine the grains and enhance the ductility of the magnetoelectric composite material.

[0133] Residual stress refers to the effects of various process factors on a workpiece during the manufacturing process. These factors have a certain effect and influence, and even after these factors disappear, some of these effects and influences remain within the workpiece. It can also be understood as residual stress, which exists within an object to maintain equilibrium when there are no external factors acting on it.

[0134] In step S43, the annealed first composite material is subjected to an in-situ polarization treatment to obtain a second composite material, namely a magnetoelectric composite material. The in-situ polarization treatment can produce more β crystals. After the in-situ polarization applies an electric field, the crystalline structure of the β phase crystals can be increased and the polymer chains can be preferentially oriented, thereby making the carbon-fluorine bonds in the magnetoelectric composite material more polar and more stable.

[0135] The second embodiment of the present invention can improve the mechanical properties, piezoelectric properties and pyroelectric properties of the magnetoelectric composite material by vacuum drying and annealing the first composite material, thereby improving the flexibility of the magnetoelectric composite material and the sensitivity of using the magnetoelectric composite material to detect temperature and pressure.

[0136] As an optional embodiment, in the vacuum drying treatment, the time for evaporating the organic solvent is 10 minutes to 15 minutes; in the annealing treatment, the annealing temperature is 130° C. to 150° C., and the annealing time is 60 minutes to 90 minutes.

[0137] It can be understood that the vacuum drying treatment is to evaporate the organic solvent in a vacuum drying oven, and the time for completely evaporating the organic solvent is at least 10 minutes. After the evaporation is completed, the first composite material is annealed. The annealing treatment is to make the ferroelectric material layer crystallize and form on the surface of the substrate layer.

[0138] It should be noted that the above-mentioned evaporation time, annealing time and annealing temperature range are the optimal drying time and temperature range obtained through experiments. Through this setting, the surface of the ferroelectric material layer can be uniform and flat when it crystallizes, without cracks or potholes, thereby improving the monitoring sensitivity of the magnetoelectric composite material to parameters such as current, temperature, and pressure.

[0139] Furthermore, in the in-situ polarization treatment, the polarization temperature is 25°C to 35°C, the polarization voltage is 25kV to 30kV, and the polarization time is 5min to 15min.

[0140] It can be understood that through in-situ polarization treatment, the crystal structure of the β-phase crystals in the magnetoelectric composite material can be enhanced, so that the CF dipoles in the magnetoelectric composite material produce preferential orientation, the piezoelectric coefficient and pyroelectric coefficient of the magnetoelectric composite material are increased, and the monitoring sensitivity of the sensor made of the magnetoelectric composite material to temperature and pressure is improved.

[0141] It should be noted that the first composite material that has completed the vacuum drying process is subjected to annealing treatment and in-situ polarization treatment to finally obtain the second composite material, ie the above-mentioned magnetoelectric composite material.

[0142] As a preferred implementation method in the second embodiment of the present invention, the polarization equipment used in the in-situ polarization treatment is a surface grid in-situ polarization equipment. Compared with the corona polarization equipment, the surface grid in-situ polarization equipment can achieve a larger polarization area, more uniform polarization, and more relaxed use conditions.

[0143] See also Figure 4 , the stirring process includes the following steps:

[0144] S21: performing a first stirring at a rotation speed of 200 rpm to 400 rpm for 6 to 8 hours to obtain a mixed solution;

[0145] S22: After the first stirring is completed, the mixed solution is stirred for a second time at a rotation speed of 100 r / min to 150 r / min and a duration of 1 h to 2 h to remove bubbles in the mixed solution.

[0146] It can be understood that the mixed solution is obtained by the first stirring, and the stirring time is at least 6 hours to ensure that the mixed solution is stirred evenly, and the mixed solution includes PVD F-HFP copolymer and composite magnetic particles; the second stirring is carried out after the first stirring is completed and the mixed solution is obtained. The second stirring can remove the bubbles in the mixed solution, so that the mixed solution has a uniform texture and no cavities are generated due to the presence of bubbles.

[0147] The rotation speed of the second stirring is lower than that of the first stirring. The bubbles generated by the first high-speed stirring of the mixed solution can be removed by the second low-speed stirring.

[0148] The mixed solution obtained after two stirrings can enable the final prepared magnetoelectric composite material to obtain higher piezoelectric coefficients, pyroelectric coefficients and magnetostriction coefficients. Experimental comparison has proved that the optimal parameters for the stirring treatment are set as follows: the speed of the first stirring is 300r / min and the duration is 7 hours, and the speed of the second stirring is 120r / min and the duration is 1 hour and 15 minutes.

[0149] It should be noted that in steps S21 and S22, both stirring methods are mechanical stirring, wherein mechanical stirring is to mix and stir by driving a stirring device through a motor and a transmission device, which is suitable for batch production of large-volume mixing and stirring, is simple and convenient to operate, and does not require special stirring devices.

[0150] See also Figure 5 The third embodiment of the present invention provides a sensor 2, comprising an electrode layer 21 and a magnetoelectric composite material 1 obtained by the above-mentioned magnetoelectric composite material preparation method, wherein the magnetoelectric composite material 1 is electrically connected to the electrode layer 21.

[0151] The ferroelectric material layer 11 is stacked between the substrate layer 12 and the electrode layer 21 .

[0152] It can be understood that the sensor 2 includes an electrically connected magnetoelectric composite material 1 and an electrode layer 21. Since the magnetoelectric composite material 1 has pyroelectric properties, piezoelectric properties and magnetostrictive properties, the charge changes caused by changes in current, temperature and pressure are converted into electrical signals. The electrode layer 21 can receive the electrical signals generated in the magnetoelectric composite material 1. Through this design, the sensor 2 can realize real-time monitoring of multiple parameters (current, temperature, pressure and other parameters), ensuring high sensitivity of monitoring and the reliability and accuracy of the monitoring results.

[0153] In addition, the electrode layer 21 can also be connected to an external device to transmit the electrical signal to an external control system, and then the control system can perform operations such as classification storage and threshold warning on the electrical signal.

[0154] Specifically, when the magnetoelectric composite material 1 receives deformation pressure, a piezoelectric effect occurs, outputting voltage and generating an electric field. This creates a potential difference between the upper and lower surfaces of the magnetoelectric composite material 1, enabling conversion between magnetic and electrical signals, and between mechanical and electrical signals. Furthermore, when the magnetoelectric composite material 1 receives a temperature change signal, a pyroelectric effect occurs, ultimately enabling conversion between thermal and electrical signals. The electrical signals generated in these processes are transmitted to the outside world through the electrode layer 21 for classification, storage, and threshold warning.

[0155] It should be noted that the electrode layer 21 provided in the third embodiment of the present invention is specifically formed by printing electrodes on the magnetoelectric composite material 1. Through this design, when the parameters such as the induced current, temperature, and pressure of the magnetoelectric composite material 1 change, the charge changes generated on the ferroelectric material layer 11 can be transmitted through the electrode layer 21.

[0156] Optionally, the electrode layer 21 is formed as follows: a plurality of screen printing screens containing hollow portions are provided, wherein the hollow portions of the screen printing screens have different sizes; the prepared magnetoelectric composite material 1 is screen printed, and a silver electrode is printed on its upper surface, thereby forming the electrode layer 21.

[0157] For further information, please refer to Figure 5 The sensor 2 further includes a protective layer 22 , which is connected to a side of the electrode layer 21 away from the ferroelectric material layer 11 , and has a thickness of 10 μm-30 μm.

[0158] It can be understood that providing a protective layer 22 with a thickness of 10 μm-30 μm can effectively prevent foreign substances such as dust, stains and oil stains from entering the interior of the sensor 2, thereby preventing these substances from causing damage to signal collection and transmission.

[0159] It should be noted that the connection between the protective layer 22 and the electrode layer 21 is specifically achieved by coating the protective layer 22 on the side of the electrode layer 21 facing away from the ferroelectric material layer 11 and then drying it. This makes the sensor 2 scratch-proof and drop-proof due to the presence of the protective layer 22, and its wear resistance is increased, thereby greatly extending the service life of the sensor 2.

[0160] Optionally, the material used for the protective layer 22 can be resin, PET film, or metal material platinum. By providing the protective layer 22, the interior of the sensor 2 can be better protected to ensure the monitoring accuracy of the sensor 2.

[0161] In the third embodiment of the present invention, a resin protective layer is used as an example for the protective layer 22. The material used for the protective layer 22 can be adjusted accordingly according to different application scenarios or usage environments. The present invention only cites one embodiment for illustration. The material composition of the protective layer 22 includes but is not limited to the aforementioned resin, PET film, and metal platinum, and can be set according to actual conditions. Any modifications, equivalent replacements, and improvements made within the principles of the present invention shall be included within the scope of protection of the present invention.

[0162] In the sensor 2 provided by the third embodiment of the present invention, the thickness of the electrode layer 21 is 100 μm-120 μm, and the thickness of the sensor 2 including the magnetoelectric composite material 1 , the electrode layer 21 , and the protective layer 22 does not exceed 200 μm.

[0163] The above is a detailed introduction to a magnetoelectric composite material, preparation method and sensor disclosed in the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention. Any modifications, equivalent replacements and improvements made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetoelectric composite material, characterized in that: comprising a ferroelectric material layer and a substrate layer stacked; The ferroelectric material layer includes a blended PVDF-HFP copolymer and composite magnetic particles, wherein the composite magnetic particles are iron-cobalt-vanadium alloy magnetic nanoparticles; The substrate layer includes a flexible circuit board and a glass substrate, and the flexible circuit board is fixed on the glass substrate; The preparation method of the magnetoelectric composite material comprises: Providing an organic solvent and PVDF-HFP powder, dissolving the PVDF-HFP powder in the organic solvent to obtain an initial solution, wherein the molar ratio of HFP to PVDF in the PVDF-HFP powder is in a range of 1:4 to 1:2, and the mass ratio of the PVDF-HFP powder to the organic solvent is 1:10; Adding the composite magnetic particles to the initial solution and stirring to obtain a mixed solution, wherein the mass of the added PVDF-HFP powder is 5 to 10 times the mass of the composite magnetic particles; Forming the ferroelectric material layer on the surface of the flexible circuit board of the substrate layer with the mixed solution to obtain a first composite material; pretreating the first composite material to obtain a second composite material, wherein the second composite material is the magnetoelectric composite material; The pretreatment comprises the following steps: performing a vacuum drying process on the first composite material to evaporate the organic solvent in the first composite material; performing an annealing treatment on the first composite material after vacuum drying, so that the ferroelectric material layer is crystallized and formed on the surface of the substrate layer; The annealed first composite material is subjected to in-situ polarization treatment to obtain the second composite material.

2. The magnetoelectric composite material according to claim 1, wherein: The thickness of the magnetoelectric composite material is 10 μm-40 μm.

3. The magnetoelectric composite material according to claim 1, wherein: During the vacuum drying process, the organic solvent is evaporated for 10 to 15 minutes. In the annealing treatment, the annealing temperature is 130° C. to 150° C., and the annealing time is 60 min to 90 min.

4. The magnetoelectric composite material according to claim 1, wherein: In the in-situ polarization treatment, the polarization temperature is 25° C. to 35° C., the polarization voltage is 25 kV to 30 kV, and the polarization time is 5 min to 15 min.

5. The magnetoelectric composite material according to claim 1, wherein The stirring process comprises the following steps: Performing a first stirring at a rotation speed of 200 rpm to 400 rpm for 6 to 8 hours to obtain the mixed solution; After the first stirring is completed, the mixed solution is stirred for a second time at a rotation speed of 100 r / min to 150 r / min and a duration of 1 h to 2 h to remove bubbles in the mixed solution.

6. A sensor, characterized in that: comprising an electrode layer and the magnetoelectric composite material according to any one of claims 1 to 5, wherein the magnetoelectric composite material is electrically connected to the electrode layer; The ferroelectric material layer is stacked between the substrate layer and the electrode layer.

7. The sensor according to claim 6, wherein: The sensor further includes a protective layer connected to a side of the electrode layer facing away from the ferroelectric material layer. The thickness of the protective layer is 10 μm-30 μm.

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