A magnetoelectric electric sensor, a preparation method thereof and a battery external short circuit detection method

Abstract

The application relates to the technical field of sensors, in particular to a magnetoelectric sensor, a preparation method thereof and a battery external short circuit detection method. The preparation method of the magnetoelectric sensor comprises the following steps: providing piezoelectric material and powder magnetic material dissolved in an organic solution to obtain a mixed solution; providing sheet-shaped magnetic material as a bottom electrode; forming a magnetoelectric film on one side of the sheet-shaped magnetic material by using the mixed solution; and providing conductive material as a top electrode arranged on the side of the magnetoelectric film far from the sheet-shaped magnetic material to obtain the magnetoelectric sensor. The technical problem that an additional function is needed for a non-contact current sensor in the prior art is solved.

Description

[Technical Field]

[0001] This invention relates to the field of sensor technology, specifically to a magnetoelectric sensor, its preparation method, and a method for detecting external short circuits in batteries. [Background Technology]

[0002] An external short circuit in a battery refers to a short circuit occurring outside the battery, where direct contact occurs between the positive and negative terminals or between the positive and negative terminals and the external environment, causing current to bypass the normal internal path of the battery. When an external short circuit occurs in a lithium-ion battery, the short circuit causes current to bypass the normal internal path of the battery, flowing directly from the positive terminal to the negative terminal or connecting directly to the external environment, resulting in a rapid increase in current. This situation may lead to battery overheating, fire, or even explosion, posing a significant safety hazard to lithium-ion batteries.

[0003] Current monitoring methods are commonly used in current technology to continuously monitor changes in battery current, thereby improving safety and reducing potential risks. This involves using specialized sensors or devices installed in the battery circuit to monitor real-time current changes. These sensors can be Hall effect sensors, resistive sensors, current transformers, etc., capable of detecting the current flowing through them and transmitting this information to a monitoring system for processing. Thresholds are set, and comparisons and analyses are performed to determine if an external short circuit exists in the battery. Specifically, current sensors can be divided into contact current sensors and non-contact current sensors based on their measurement principles and operating environments. However, contact current sensors pose safety risks such as direct electric shock and are unsuitable for high-risk environments. Non-contact current sensors are widely used and pose no risk of direct electric shock, making them a research hotspot in recent decades. However, traditional non-contact current sensors require an external power supply, resulting in high power consumption and high manufacturing costs. [Summary of the Invention]

[0004] To address the technical problem that non-contact current sensors in the prior art require additional power, this invention provides a magnetoelectric sensor and its fabrication method, as well as a method for detecting external short circuits in batteries.

[0005] The solution to the technical problem of this invention is to provide a method for fabricating a magnetoelectric sensor, comprising:

[0006] A piezoelectric material and a powdered magnetic material are dissolved in an organic solution to obtain a mixed solution;

[0007] A sheet-like magnetic material is provided as the bottom electrode, and the mixed solution is used to form a magnetoelectric thin film on one side of the sheet-like magnetic material;

[0008] A magnetoelectric sensor is obtained by providing a conductive material as a top electrode on the side of the magnetoelectric thin film away from the sheet-like magnetic material.

[0009] Preferably, the formation of the magnetoelectric thin film includes:

[0010] The mixed solution is dropped onto one side of a sheet of magnetic material and then coated to form a film of the mixture.

[0011] The mixture film is dried and annealed sequentially to form a magnetoelectric thin film on a sheet magnetic material.

[0012] Preferably, the powder magnetic material includes either Tefernol-D rare earth alloy powder or iron oxide powder.

[0013] Preferably, the sheet-like magnetic material includes any one of Metglass soft magnetic alloy, Teferno 1D rare earth alloy, FeCoV alloy, and FeGa alloy.

[0014] Preferably, the piezoelectric material includes any one of PVDF, PLLA, and LMPE.

[0015] Preferably, the conductive material includes either copper sheet or conductive film made of silver paste.

[0016] Preferably, the conductive film made from the silver paste includes either magnetron sputtering or stencil printing.

[0017] Preferably, the doping ratio of the powdered magnetic material in the magnetoelectric thin film is 5wt%-30wt%.

[0018] To solve the above-mentioned technical problems, the present invention also provides a magnetoelectric sensor, which is a magnetoelectric sensor prepared using the above-mentioned magnetoelectric sensor preparation method.

[0019] To solve the above-mentioned technical problems, this invention also provides a method for detecting external short circuits in a battery, which utilizes the aforementioned magnetoelectric sensor to detect external short circuits in the battery, including:

[0020] The magnetoelectric sensor is placed externally on the side of the battery.

[0021] A terminal is provided that connects to a magnetoelectric sensor. If a piezoelectric signal is received from the magnetoelectric sensor, it is determined that there is an external short circuit in the battery; otherwise, it is determined that the battery is in normal condition.

[0022] Compared with existing technologies, the magnetoelectric sensor, its preparation method, and battery external short-circuit detection method provided by this invention have the following advantages:

[0023] 1. A method for fabricating a magnetoelectric sensor provided in this embodiment of the invention includes the following steps: dissolving a piezoelectric material and a powdered magnetic material in an organic solution to obtain a mixed solution; providing a sheet-like magnetic material as a bottom electrode, and forming a magnetoelectric thin film on one side of the sheet-like magnetic material using the mixed solution; and providing a conductive material as a top electrode disposed on the side of the magnetoelectric thin film away from the sheet-like magnetic material to obtain a magnetoelectric sensor. By doping the piezoelectric material with powdered magnetic material, a novel magnetoelectric composite material was successfully prepared, and a magnetoelectric sensor was fabricated using this composite material. This method utilizes the piezoelectric effect of the piezoelectric elastomer and the magnetostrictive effect generated in the target film by the powdered material. Compared with existing technologies, this invention has advantages such as non-contact operation, small size, flexible structure, self-powered operation, low cost, and high temperature resistance. Furthermore, the use of a sheet-like magnetic material as the bottom electrode further enhances the sensitivity of the magnetoelectric sensor.

[0024] 2. In the method for preparing a magnetoelectric sensor provided in this embodiment of the invention, the formation of a magnetoelectric thin film includes: dropping a mixed solution onto one side of a sheet-like magnetic material and forming a uniformly thick mixed film layer by scraping; drying and annealing the mixed film layer sequentially to form a magnetoelectric thin film on the sheet-like magnetic material. Through these steps, the thickness of the magnetoelectric thin film can be adjusted to make the manufactured magnetoelectric sensor adaptable to different working environments.

[0025] 3. The method for preparing a magnetoelectric sensor provided in this embodiment of the invention involves making a conductive thin film from silver paste, which includes either magnetron sputtering or stencil printing. Magnetron sputtering has the advantages of producing a uniform, dense film with high adhesion strength, while stencil printing has the advantages of low preparation cost, fast preparation speed, and suitability for large-area preparation.

[0026] 4. The method for preparing a magnetoelectric sensor provided in this embodiment of the invention involves a doping ratio of 5wt% to 30wt% of powdered magnetic material in the magnetoelectric thin film, thereby ensuring that the manufactured magnetoelectric sensor has high sensitivity and can generate magnetostrictive and piezoelectric effects when the external magnetic field changes.

[0027] 5. This invention also provides a magnetoelectric sensor, which is prepared by the above-mentioned method for preparing a magnetoelectric sensor. A novel magnetoelectric composite material is successfully prepared by doping a piezoelectric elastomer with iron oxide. The magnetoelectric sensor made from this composite material can be applied to battery status monitoring to detect changes in external pressure and changes in current during battery charging and discharging.

[0028] 6. This embodiment of the invention also provides a method for detecting external short circuits in a battery, comprising: placing a magnetoelectric sensor externally on one side of the battery; providing a terminal connected to the magnetoelectric sensor; if a piezoelectric signal is received from the magnetoelectric sensor, it is determined that the battery has an external short circuit; otherwise, it is determined that the battery is in normal condition. The magnetoelectric sensor can detect the charging and discharging state of the battery in real time, avoiding safety accidents. During operation, the magnetoelectric sensor does not directly contact the pouch battery during detection; instead, it utilizes the piezoelectric effect and magnetostriction effect to generate a piezoelectric signal, requiring no additional power supply. [Attached Image Description]

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of a method for preparing a magnetoelectric sensor provided in the first embodiment of the present invention.

[0031] Figure 2 This is a flowchart of forming a magnetoelectric thin film provided in the first embodiment of the present invention.

[0032] Figure 3 This is a flowchart of a battery external short circuit detection method provided in the third embodiment of the present invention.

Detailed Implementation Methods

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0035] Please see Figure 1 and Figure 2 The first embodiment of the present invention provides a method for preparing a magnetoelectric sensor, comprising the following steps:

[0036] S1: Piezoelectric materials and powdered magnetic materials are dissolved in an organic solution to obtain a mixed solution;

[0037] S2: Provide a sheet-like magnetic material as the bottom electrode, and form a magnetoelectric thin film on one side of the sheet-like magnetic material by mixing the solution;

[0038] S3: A magnetoelectric sensor is obtained by providing a conductive material as the top electrode and setting it on the side of the magnetoelectric thin film away from the sheet magnetic material.

[0039] It should be noted that piezoelectric materials are used to prepare piezoelectric elastomers. As an organic material, piezoelectric materials refer to materials that possess both piezoelectric effect and elastic properties. The piezoelectric effect refers to the polarization of a material when mechanical stress or an electric field is applied, resulting in charge separation and a potential difference. When the applied stress disappears, the elastic property refers to the material's ability to recover its shape and size.

[0040] It should be noted that, understandably, by combining piezoelectric materials with powdered magnetic materials to prepare magnetic thin films, when external magnetic fields change, the powdered magnetic materials in the magnetic thin film cause deformation, thereby generating a piezoelectric effect. During battery charging and discharging, if an external short circuit occurs, the current will increase sharply in a short time, causing a change in the nearby magnetic field. In this embodiment, in step S2, by forming a magnetoelectric thin film on a sheet-like magnetic material, both the sheet-like magnetic material and the magnetoelectric thin film can generate a magnetostrictive effect when the external magnetic field changes. The sheet-like magnetic material can further increase the deformation of the magnetoelectric thin film, causing the piezoelectric material to generate a larger piezoelectric effect and output a higher piezoelectric signal. This makes the magnetoelectric sensor prepared in this embodiment more sensitive and suitable for detecting whether there is an external short circuit during battery charging and discharging. It has the advantages of not requiring additional power supply and having low manufacturing cost.

[0041] In this embodiment, the piezoelectric material specifically includes any one of PVDF, PLLA, and LMPE.

[0042] It should be noted that PVDF stands for polyvinylidene fluoride. PVDF is a thermoplastic polymer that is commonly used to prepare products such as films, pipes, and cable insulation. It is widely used because of its good chemical stability and heat resistance.

[0043] It's important to note that LMPE, short for Low Modulus Piezoelectric Elastomer, is a special type of piezoelectric elastomer material characterized by its relatively low elastic modulus. Compared to traditional piezoelectric ceramics and piezoelectric polymers, LMPE's lower elastic modulus makes it more suitable for flexible and deformable applications. LMPE materials typically consist of a piezoelectric polymer and an elastic matrix. The piezoelectric polymer imparts piezoelectric properties to LMPE, generating charge separation and potential difference when pressure or an electric field is applied, while the elastic matrix provides the material's flexibility and deformability.

[0044] It should be noted that PLLA stands for polylactic acid, a biodegradable polymer made from renewable resources such as corn starch. PLLA has advantages such as a low elastic modulus, high piezoelectric properties, and high magnetoelectric conversion efficiency in its composite system.

[0045] In this embodiment, the powder magnetic material includes either Tefernol-D rare earth alloy powder or iron oxide powder.

[0046] It should be noted that Tefernol-D rare earth alloy powder and iron oxide powder have low production costs, stable chemical properties, and certain magnetostrictive properties, thus ensuring performance while reducing the development cost of magnetoelectric composite devices. The magnetoelectric thin film prepared in step S2 includes powdered magnetic materials, which can produce significant deformation when induced by changes in the external magnetic field, thereby causing the piezoelectric material in the magnetic thin film to produce a piezoelectric effect.

[0047] In this embodiment, the sheet-like magnetic material includes any one of Metglass soft magnetic alloy, Teferno 1D rare earth alloy, FeCoV alloy, and FeGa alloy.

[0048] It should be noted that Metglas (also known as an amorphous alloy) is an amorphous soft magnetic alloy composed of elements such as iron, nickel, silicon, and boron. This material exhibits extremely low hysteresis and loss characteristics. Terfenol-D is a rare-earth metal terbium (Tb)-based magnetostrictive alloy composed of terbium, iron, and lutetium (Dy). This alloy possesses a very high magnetostrictive effect and is widely used in sound generators, sound sensors, and magnetoelectric sensors. FeCoV alloy is an iron-cobalt-vanadium alloy with excellent toughness and magnetic properties. FeGa alloy is a magnetic material composed of iron and gallium (Ga). This alloy exhibits excellent magnetic domain control and mechanoelastic properties. The above-mentioned sheet-like magnetic materials each possess different magnetic properties, strain characteristics, and process tunability, allowing for selection based on specific application requirements.

[0049] It should be noted that the magnetoelectric thin film can be prepared with different thicknesses based on different application requirements. Specifically, to facilitate the detection of external short circuit states during battery charging and discharging, in step S1 of this embodiment, if PVDF material is used as the piezoelectric material, the thickness of the prepared magnetoelectric thin film is 10-30 μm; if PLLA material is used, the thickness is 20-40 μm; and if LMPE material is used, the thickness is 80-120 μm. The particle size of the powdered magnetic material can preferably be in the range of 0-50 μm. It is understood that the magnetoelectric sensor prepared by the method provided in this embodiment also has the advantages of small size and easy installation.

[0050] It should be noted that, in this embodiment, depending on different usage scenarios and specific needs, if the sheet magnetic material used as the bottom electrode is selected as Metglass soft magnetic alloy or FeCoV alloy, the magnetoelectric sensor made there is a certain degree of flexibility, which makes it easy to install the magnetoelectric sensor during the assembly process.

[0051] Specifically, in step S1, the organic solvent includes one or more of dichloromethane, trichloromethane, and N,N-dimethylformamide (DMF), which are used to dissolve the piezoelectric material and the powder magnetic material. After the piezoelectric material and the powder magnetic material are added to the organic solvent, a mixed solution is formed by mechanical stirring.

[0052] It should be noted that different piezoelectric materials have different dissolution rates. If PLLA and PVDF are used as piezoelectric materials, mechanical stirring at room temperature (e.g., 20℃-30℃) for more than 8 hours is required. If LMPE is used as piezoelectric materials, mechanical stirring at room temperature (e.g., 20℃-30℃) for 2 hours is sufficient.

[0053] It should be noted that, in order to eliminate the bubbles generated by stirring, the mixed solution can be allowed to stand after stirring. Specifically, the standing time is preferably 2 minutes, 4 minutes or 6 minutes to avoid the organic solvent from evaporating due to excessive time.

[0054] It's important to note that in polymers, if the chemical bonds between molecular chains are linear, the polymer is linear; however, if the molecular chains form a cross-linked structure, the polymer is cross-linked. This cross-linked structure can give the polymer higher elasticity and durability. When preparing a mixed solution, if LMPE is used as the piezoelectric material, after adding LMPE and powdered magnetic materials to an organic solvent, a cross-linking agent is needed to connect the polymer chains, forming a cross-linked structure. This creates a network structure between the LMPE molecular chains, thus imparting elasticity and deformation capability to the material, forming a piezoelectric elastomer. Dicumyl peroxide (DCP) can be used as the cross-linking agent, offering advantages such as high cross-linking efficiency, low cost, and improved heat resistance.

[0055] It should be noted that, in order to ensure that the fabricated magnetoelectric sensor has excellent sensitivity, excessive addition of powdered magnetic material should be avoided to prevent it from increasing the modulus of the elastomer, as the piezoelectric properties of the elastomer are enhanced by reducing the modulus. Conversely, insufficient addition will result in less deformation of the magnetic film when the external magnetic field changes, thus reducing the output piezoelectric signal. By adjusting the ratio of powdered magnetic material to piezoelectric material added in step S1, the doping ratio of powdered magnetic material in the magnetoelectric film fabricated in step S2 is adjusted to 5wt%-30wt%, such as 5wt%, 10wt%, 15wt%, 20wt%, 35wt%, etc., without specific limitations in this embodiment.

[0056] Step S2 specifically includes:

[0057] S21: The mixed solution is dropped onto one side of the sheet magnetic material and a mixed film is formed by scraping.

[0058] S22: The mixture film is dried and annealed in sequence to form a magnetoelectric thin film on a sheet magnetic material.

[0059] It should be noted that in step S21, the mixed solution is coated to form a uniformly thick mixed film layer on the sheet magnetic material, thereby making the magnetoelectric thin film produced in step S22 uniform in thickness and avoiding affecting the output of the piezoelectric signal of the magnetoelectric sensor.

[0060] It should be noted that in step S22, the organic solvents such as dichloromethane, trichloromethane or DMF are evaporated by drying and annealing the mixture film layer, and finally the mixture film layer is formed on the conductive substrate.

[0061] It should be noted that different temperatures and times are required during the annealing process depending on the piezoelectric material. Specifically, if PLLA is used as the piezoelectric material, a preferred method is to hold it at 140°C for 1 hour; if PVDF is used as the piezoelectric material, a preferred method is to hold it at 140°C for 45 minutes; and if LMPE is used as the piezoelectric material, a preferred method is to hold it at 160°C for 10 minutes.

[0062] It should be noted that if PVDF is used as the piezoelectric material, a polarization process is required after step S22 to separate the generated positive and negative charges. Polarization of PVDF can enhance its piezoelectric properties, making it more suitable for applications such as magnetoelectric sensors and piezoelectric transducers. Through polarization, the alignment of the molecular chains in PVDF can be adjusted, resulting in higher piezoelectric performance and stability.

[0063] Furthermore, in step S3, the conductive material includes either a copper sheet or a conductive film made of silver paste. It is understood that both copper sheets and conductive films made of silver paste have good conductivity, which is beneficial for transmitting the piezoelectric signal generated by the magnetoelectric film.

[0064] Furthermore, in this embodiment, a preferred method is to use a conductive film made of silver paste as the conductive material. Compared with copper sheets, the conductive film made of silver paste has better conductivity and can make the manufactured magnetoelectric sensor smaller in size, and it is also easier to control the thickness of the top electrode.

[0065] It should be noted that conductive thin films made using silver paste include either magnetron sputtering or stencil printing. Specifically, magnetron sputtering is a technique that uses high-energy particles to bombard the target film surface, sputtering atoms or molecules from the silver paste and depositing them onto the target film to form a thin film. Its advantages include producing uniform, dense films with high adhesion strength, and it is suitable for preparing various types of thin films, including single-layer, multilayer, and composite films. Stencil printing, on the other hand, is a technique that prints a pattern onto a substrate. During the printing process, silver paste is pressed into the target film surface through mesh openings. Stencil printing offers advantages such as low production cost, fast production speed, and suitability for large-area fabrication.

[0066] It should be noted that Ag has excellent conductivity. In this embodiment, the sensitivity of the magnetoelectric sensor is improved by pasting silver paste with a thickness of 20 μm onto the surface of the magnetoelectric film through stencil printing.

[0067] As can be understood, the magnetoelectric sensor fabricated by the method provided in this embodiment consists of a conductive thin film made of silver paste, a magnetoelectric thin film, and a sheet-like magnetic material stacked sequentially. The conductive thin film made of silver paste serves as the top electrode, and the sheet-like magnetic material serves as the bottom electrode.

[0068] A second embodiment of the present invention also provides a magnetoelectric sensor, fabricated using the aforementioned method. The magnetoelectric sensor includes a top electrode, a magnetoelectric thin film, and a bottom electrode stacked sequentially. Specifically, two wires, such as silver wires, are used; one is connected to the bottom electrode, and the other to the top electrode. The side of the wire furthest from the magnetoelectric sensor is connected to a terminal, such as a data acquisition unit, which collects the piezoelectric signal generated by the magnetoelectric sensor. This sensor can be used to detect changes in external magnetic fields and pressure.

[0069] For example, the magnetoelectric sensor provided in this embodiment can function similarly to a pressure sensor. It can be placed on an external object, such as a battery, or the battery can be placed 10 mm, 20 mm, or 30 mm above the magnetoelectric sensor. When the battery bulges or falls due to external factors such as external force, impact, or vibration, the magnetoelectric sensor deforms and outputs a piezoelectric signal. The piezoelectric signal is collected by the terminal to obtain information about the battery bulging or falling.

[0070] For example, the magnetoelectric sensor provided in this embodiment can also be used to detect whether there is an external short circuit in the battery during the charging and discharging process. Specifically, the magnetoelectric sensor is placed on the outer periphery or one side of the battery. When the battery has an external short circuit, the instantaneous increase in current will cause the nearby magnetic field to change, thereby causing the sheet-like magnetic material of the bottom electrode and the magnetoelectric thin film to produce a magnetostrictive effect. The piezoelectric elastomer in the magnetoelectric thin film will produce a piezoelectric effect and output a piezoelectric signal.

[0071] It should be noted that, since the bottom electrode uses sheet-like magnetic material that can generate a magnetostrictive effect, and the magnetoelectric thin film is attached to the bottom electrode, when the external magnetic field changes, the magnetoelectric thin film can generate a large deformation, so as to output a larger piezoelectric signal. The magnetoelectric sensor provided in this application has greater sensitivity, making it easier for users to detect external short circuits in the battery in a timely manner.

[0072] Please see Figure 3 The third embodiment of the present invention provides a battery external short circuit detection method, which includes detecting the battery external short circuit using a magnetoelectric sensor provided in the above embodiments, specifically including:

[0073] S100: The magnetoelectric sensor is placed externally on the side of the battery;

[0074] S200: Provides a terminal for connecting to the magnetoelectric sensor;

[0075] S 310: If a piezoelectric signal from the magnetoelectric sensor is received, it is determined that there is an external short circuit in the battery;

[0076] S 320; If no piezoelectric signal is received from the magnetoelectric sensor, the battery is considered to be in normal condition.

[0077] It should be noted that S310 and S320 are two different execution methods. That is, after step S200, based on the result of the judgment, either S310 or S320 is selected for execution.

[0078] It should be noted that sheet materials of Metglas soft magnetic alloy or FeCoV alloy can be selected as the bottom electrode, so that the resulting magnetoelectric sensor is flexible and easy to place in corners and edges, thereby reducing space occupation.

[0079] It should be noted that the magnetoelectric sensor can be attached to the outer periphery of the battery and can be set at a distance of 5mm, 10mm, 5mm, etc. It is necessary to avoid the magnetoelectric sensor failing in case the battery is short-circuited due to excessive distance.

[0080] Understandably, by using magnetoelectric sensors to detect whether there is an external short circuit during the charging and discharging process of the battery, and when the battery current changes drastically, the magnetoelectric sensors can provide timely feedback, allowing users to understand the charging and discharging status of the pouch battery through the terminal in a timely manner, thus avoiding safety accidents.

[0081] Compared with existing technologies, the magnetoelectric sensor, its preparation method, and battery external short-circuit detection method provided by this invention have the following advantages:

[0082] 1. A method for fabricating a magnetoelectric sensor provided in this embodiment of the invention includes the following steps: dissolving a piezoelectric material and a powdered magnetic material in an organic solution to obtain a mixed solution; providing a sheet-like magnetic material as a bottom electrode, and forming a magnetoelectric thin film on one side of the sheet-like magnetic material using the mixed solution; and providing a conductive material as a top electrode disposed on the side of the magnetoelectric thin film away from the sheet-like magnetic material to obtain a magnetoelectric sensor. By doping the piezoelectric material with powdered magnetic material, a novel magnetoelectric composite material was successfully prepared, and a magnetoelectric sensor was fabricated using this composite material. This method utilizes the piezoelectric effect of the piezoelectric elastomer and the magnetostrictive effect generated in the target film by the powdered material. Compared with existing technologies, this invention has advantages such as non-contact operation, small size, flexible structure, self-powered operation, low cost, and high temperature resistance. Furthermore, the use of a sheet-like magnetic material as the bottom electrode further enhances the sensitivity of the magnetoelectric sensor.

[0083] 2. In the method for preparing a magnetoelectric sensor provided in this embodiment of the invention, the formation of a magnetoelectric thin film includes: dropping a mixed solution onto one side of a sheet-like magnetic material and forming a uniformly thick mixed film layer by scraping; drying and annealing the mixed film layer sequentially to form a magnetoelectric thin film on the sheet-like magnetic material. Through these steps, the thickness of the magnetoelectric thin film can be adjusted to make the manufactured magnetoelectric sensor adaptable to different working environments.

[0084] 3. The method for preparing a magnetoelectric sensor provided in this embodiment of the invention involves making a conductive thin film from silver paste, which includes either magnetron sputtering or stencil printing. Magnetron sputtering has the advantages of producing a uniform, dense film with high adhesion strength, while stencil printing has the advantages of low preparation cost, fast preparation speed, and suitability for large-area preparation.

[0085] 4. The method for preparing a magnetoelectric sensor provided in this embodiment of the invention involves a doping ratio of 5wt% to 30wt% of powdered magnetic material in the magnetoelectric thin film, thereby ensuring that the manufactured magnetoelectric sensor has high sensitivity and can generate magnetostrictive and piezoelectric effects when the external magnetic field changes.

[0086] 5. This invention also provides a magnetoelectric sensor, which is prepared by the above-mentioned method for preparing a magnetoelectric sensor. A novel magnetoelectric composite material is successfully prepared by doping a piezoelectric elastomer with iron oxide. The magnetoelectric sensor made from this composite material can be applied to battery status monitoring to detect changes in external pressure and changes in current during battery charging and discharging.

[0087] 6. This embodiment of the invention also provides a method for detecting external short circuits in a battery. A magnetoelectric sensor is externally placed on one side of the battery. A terminal is connected to the magnetoelectric sensor. If a piezoelectric signal is received from the magnetoelectric sensor, it is determined that the battery has an external short circuit; otherwise, it is determined that the battery is in normal condition. The magnetoelectric sensor can detect the charging and discharging state of the battery in real time, avoiding safety accidents. During operation, the magnetoelectric sensor does not directly contact the pouch battery during detection. Instead, it utilizes the piezoelectric effect and magnetostriction effect to generate a piezoelectric signal, requiring no additional power supply.

[0088] The foregoing has provided a detailed description of a magnetoelectric sensor, its preparation method, and a battery external short-circuit detection method disclosed in the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention. Any modifications, equivalent substitutions, and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating a magnetoelectric sensor, characterized in that, include: A piezoelectric material and a powdered magnetic material are dissolved in an organic solution to obtain a mixed solution; A sheet-like magnetic material is provided as the bottom electrode, and the mixed solution is used to form a magnetoelectric thin film on one side of the sheet-like magnetic material; A magnetoelectric sensor is obtained by providing a conductive material as a top electrode on the side of the magnetoelectric thin film away from the sheet-like magnetic material. The doping ratio of the powdered magnetic material in the magnetoelectric thin film is 5wt%-30wt%; the magnetoelectric thin film is integrated with the sheet-like magnetic material by scraping; the sheet-like magnetic material generates a magnetostrictive effect when the external magnetic field changes, which directly drives the magnetoelectric thin film to deform in tandem to output a piezoelectric signal.

2. The method for fabricating a magnetoelectric sensor as described in claim 1, characterized in that, The formation of the magnetoelectric thin film includes: The mixed solution is dropped onto one side of a sheet of magnetic material and then coated to form a film of the mixture. The mixture film is dried and annealed sequentially to form a magnetoelectric thin film on a sheet magnetic material.

3. The method for fabricating a magnetoelectric sensor as described in claim 1, characterized in that, The powdered magnetic material includes either Tefernol-D rare earth alloy powder or iron oxide powder.

4. The method for fabricating a magnetoelectric sensor as described in claim 1, characterized in that, The sheet-like magnetic material includes any one of Metglass soft magnetic alloy, Tefernol-D rare earth alloy, FeCoV alloy, and FeGa alloy.

5. The method for fabricating a magnetoelectric sensor as described in claim 1, characterized in that, The piezoelectric material includes any one of PVDF, PLLA, and LMPE.

6. The method for fabricating a magnetoelectric sensor as described in claim 1, characterized in that, The conductive material includes either copper sheet or conductive film made of silver paste.

7. The method for fabricating a magnetoelectric sensor as described in claim 6, characterized in that, The conductive film made from the silver paste includes either magnetron sputtering or stencil printing.

8. A magnetoelectric sensor, characterized in that, A magnetoelectric sensor manufactured using a magnetoelectric sensor fabrication method as described in any one of claims 1-7.

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