A thermistor with nanoparticle film and preparation method thereof

Abstract

The present invention provides a thermistor with a nanoparticle film and a method for preparing the same. The thermistor comprises a substrate, a conductive filler, and a composite thermistor material. The conductive filler is dispersed within the substrate and overlaps to form a conductive network. The composite thermistor material is dispersed within the substrate and comprises a thermistor ceramic material with a positive temperature coefficient and a nanoparticle film disposed on the surface of the thermistor ceramic material. The nanoparticle film comprises a thermally responsive shape memory material. The thermistor provided by the present invention has a small volume increase, thereby reducing the probability of the conductive network formed by the conductive filler being broken apart. This helps the thermistor's resistance value after over-protection approach its original value before over-protection, thereby improving its stability.

Description

Technical Field

[0001] The present invention relates to the technical field of thermistors, and in particular to a thermistor with a nanoparticle film and a preparation method thereof. Background Art

[0002] Thermistors are divided into positive temperature coefficient thermistors (PTC thermistor, i.e. Positive Temperature Coefficient thermistor) and negative temperature coefficient thermistor (NTC thermistor, i.e. Negative Temperature Coefficient thermistor) according to their temperature coefficient. Their resistance values ​​can change with changes in temperature, which makes them suitable as an over-current protection electronic component. Therefore, they can be widely used in overcurrent and overheating protection in industrial automation control systems, electronic equipment, medical equipment, automotive electronic control systems, aerospace, military and other fields.

[0003] However, in the related art, after the positive temperature coefficient thermistor is over-protected, its resistance value at room temperature is significantly different from its original value before the over-protection, which results in its insufficient stability. Summary of the Invention

[0004] The present invention provides a barium titanate-based thermistor with a nanoparticle film and a preparation method thereof. The thermistor can make its resistance value close to the original value before overprotection after overprotection, so as to improve its stability.

[0005] A first aspect of the present invention provides a thermistor, comprising:

[0006] matrix;

[0007] Conductive fillers are dispersed in the matrix and overlap with each other to form a conductive network;

[0008] A composite thermosensitive material is dispersed in the matrix, wherein the composite thermosensitive material comprises a thermosensitive ceramic material with a positive temperature coefficient and a nanoparticle film arranged on the surface of the thermosensitive ceramic material, wherein the nanoparticle film comprises a shape memory material with thermal response.

[0009] According to any of the aforementioned embodiments of the present invention, the nanoparticle film further comprises a conductive nanomaterial, and the mass ratio of the conductive nanomaterial to the shape memory material is 1:(10-20).

[0010] According to any of the aforementioned embodiments of the present invention, the shape memory material includes shape memory ceramics and / or shape memory polymers.

[0011] According to any of the aforementioned embodiments of the present invention, the shape memory material includes shape memory ceramics, and the shape memory ceramics include at least one of zirconium oxide nanoparticles, cerium oxide nanoparticles, and titanium oxide nanoparticles.

[0012] According to any of the aforementioned embodiments of the present invention, the shape memory material includes a shape memory polymer, and the shape memory polymer includes at least one of polyurethane, polylactone, polystyrene, and epoxy resin.

[0013] According to any of the aforementioned embodiments of the present invention, the conductive nanomaterial includes one or more of nickel nanoparticles, single-walled carbon nanotubes, multi-walled carbon nanotubes and iron nanoparticles.

[0014] According to any of the aforementioned embodiments of the present invention, the thickness of the nanoparticle film is 10 nm-100 nm.

[0015] According to any of the aforementioned embodiments of the present invention, the mass percentage of the composite thermosensitive material in the thermistor is 10%-25%.

[0016] According to any of the aforementioned embodiments of the present invention, the conductive filler has a mass percentage of 5%-10% in the thermistor.

[0017] A second aspect of the present invention provides a method for preparing a thermistor according to any embodiment of the first aspect of the present invention, comprising:

[0018] Dispersing a raw material of a nanoparticle film in a solvent to form a slurry, wherein the raw material of the nanoparticle film includes a shape memory material having a thermal response;

[0019] impregnating a thermosensitive ceramic material having a positive temperature coefficient into the slurry, and forming a nanoparticle film on the surface of the thermosensitive ceramic material after drying to obtain a composite thermosensitive material;

[0020] The raw material of the matrix, the conductor filler and the composite thermal-sensitive material are mixed, and the mixture is pressed and sintered to obtain the thermistor.

[0021] The third aspect of the present invention provides a temperature sensor, including the barium titanate-based thermistor provided in the second aspect of the present invention as described in any embodiment of the first aspect of the present invention or the barium titanate-based thermistor prepared by the preparation method described in any embodiment of the second aspect of the present invention.

[0022] The present invention provides a thermistor with a nanoparticle film and a method for preparing the same. The thermistor comprises a substrate, a conductive filler, and a composite thermosensitive material. The conductive filler is dispersed within the substrate and overlaps to form a conductive network. The composite thermosensitive material is dispersed within the substrate and comprises a thermosensitive ceramic material having a positive temperature coefficient and a nanoparticle film disposed on the surface of the thermosensitive ceramic material. The nanoparticle film comprises a thermally responsive shape memory material. This technical solution, by disposing a nanoparticle film on the surface of the thermosensitive ceramic material, and the nanoparticle film comprises a thermally responsive shape memory material, imparts a shape memory function to the nanoparticle film. This helps reduce the volume increase of the thermistor after overprotection, thereby reducing the probability of the conductive network formed by the conductive filler being disassembled. This helps the thermistor's resistance value approach its original value before overprotection after overprotection, thereby improving its stability.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. DETAILED DESCRIPTION

[0024] Unless otherwise specified, the terms used in the present invention have the common meanings that are commonly understood by those skilled in the art.

[0025] Unless otherwise specified, the values ​​of the parameters mentioned in the present invention can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the embodiments of the present invention.

[0026] The temperature of a positive temperature coefficient (PTC) thermistor increases rapidly with abnormally high current. When the temperature reaches the Curie point, the thermistor's thermal ceramic material expands, breaking up the conductive network formed by the conductive filler within it, causing its resistance to increase rapidly, thereby reducing the current and achieving over-protection. Ideally, after the abnormally high current is eliminated, the thermal expansion of the thermistor ceramic material disappears and returns to its original shape. The thermal expansion causes the broken conductive network to recover, restoring the thermistor's resistance to its original value before the over-protection condition. However, in reality, the high-temperature expansion of the thermistor ceramic material causes its structure to change, resulting in a volume significantly larger than before the over-protection condition. This causes part of the conductive network to remain broken up, causing the thermistor's resistance at room temperature to differ significantly from its original value before the over-protection condition, leading to insufficient stability.

[0027] In view of this, the present invention provides a barium titanate-based thermistor with a nanoparticle film and a preparation method thereof, wherein the resistance value of the thermistor can be close to the original value before overprotection after overprotection, thereby improving its stability.

[0028] In a first aspect, the present invention provides a thermistor comprising a matrix, a conductive filler, and a composite thermistor material, wherein the conductive filler is dispersed in the matrix and overlaps with each other to form a conductive network; the composite thermistor material is dispersed in the matrix, the composite thermistor material comprising a thermistor ceramic material having a positive temperature coefficient and a nanoparticle film disposed on the surface of the thermistor ceramic material, the nanoparticle film comprising a shape memory material having a thermal response.

[0029] The thermistor with a nanoparticle film provided by the present invention is provided with a nanoparticle film on the surface of a thermistor ceramic material. The nanoparticle film includes a shape memory material with thermal response. This enables the nanoparticle film to have a shape memory function. When the thermistor is overprotected, the volume increase of the thermistor ceramic material is reduced, thereby reducing the probability of the conductive network formed by the conductive filler being disassembled. As a result, the resistance value of the thermistor can be close to the original value before the overprotection after the overprotection, thereby improving its stability.

[0030] In some embodiments of the present invention, the matrix includes a crystalline polymer, such as polyethylene, polypropylene, polyfluoroolefin, and the like.

[0031] In embodiments of the present invention, the nanoparticle film includes a thermally responsive shape memory material. This helps minimize the shape change, or volume increase, of the thermistor after overprotection. Furthermore, the nanoparticle film may include other suitable materials to reduce the resistance of the thermistor at room temperature, thereby lowering its energy consumption.

[0032] In some embodiments of the present invention, the nanoparticle film further comprises a conductive nanomaterial, and the mass ratio of the conductive nanomaterial to the shape memory material is 1:(10-20). This mass ratio of the conductive nanomaterial to the shape memory material within the above-mentioned suitable range not only enables the thermistor to have a lower resistance value at room temperature, thereby reducing its energy consumption, but also further reduces the volume increase of the thermistor ceramic material after overprotection, thereby effectively reducing the rate of change of the thermistor's resistance value.

[0033] Exemplarily, the mass ratio of the conductive nanomaterial to the shape memory material can be, but is not limited to, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, etc.

[0034] In some embodiments of the present invention, the conductive nanomaterial comprises one or more of nickel nanoparticles, single-walled carbon nanotubes, multi-walled carbon nanotubes, and iron nanoparticles.

[0035] In the above embodiment, selecting a suitable shape memory material can help the thermistor material have a lower volume increase after overprotection, so that the recovery rate of the conductive network formed by the conductive filler will also increase, which can further help the resistance value of the thermistor after overprotection to approach the original value before overprotection, thereby further improving the stability of the thermistor.

[0036] In some embodiments of the present invention, the shape memory material includes shape memory ceramics and / or shape memory polymers. The shape memory material, including the aforementioned suitable materials, can improve the structural strength of the composite thermal-sensitive material and reduce the volume increase of the thermal-sensitive ceramic material. It can also help increase the resistance of the composite thermal-sensitive material during over-protection, thereby enhancing the over-protection effect.

[0037] Exemplarily, the shape memory material includes shape memory ceramics, and the shape memory ceramics include at least one of zirconium oxide nanoparticles, cerium oxide nanoparticles, and titanium oxide nanoparticles. These nanoparticles can further enhance the stability of the thermistor while also further improving its overload protection effect.

[0038] In other examples, the shape memory material includes a shape memory polymer, and the shape memory polymer includes at least one of polyurethane, polylactone, polystyrene, and epoxy resin.

[0039] The nanoparticle film formed by the above materials can improve its structural stability when its thickness is within an appropriate range, thereby further helping to reduce the volume increase of the thermistor.

[0040] In some embodiments of the present invention, the thickness of the nanoparticle film is 10 nm to 100 nm.

[0041] The thickness of the nanoparticle film is the distance along the radial direction of the thermosensitive ceramic material between the side of the nanoparticle film closest to the thermosensitive ceramic material surface and the side of the nanoparticle film away from the thermosensitive ceramic material surface. This thickness can be measured using SEM, EDS, TEM, XPS, and other methods.

[0042] In some examples, the thickness of the nanoparticle film can be, but is not limited to, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm, 51 nm, 52 nm, 53 nm, 54 nm, 55 nm, 56 nm, 57 nm, 58 nm, 59 nm, 60 nm, 61 nm, 62 nm, 63 nm, 64 nm, 65 nm, 66 nm, 67 nm, 68 nm, 69 nm, 70 nm, 71 nm, 72 nm, 73 nm, 74 nm, 75 nm, 76 nm, 77 nm, 78 nm, 79 nm, 6nm, 57nm, 58nm, 59nm, 60nm, 61nm, 62nm, 63nm, 64nm, 65nm, 66nm, 67nm, 68nm, 69nm, 70nm, 71nm, 72nm, 73nm, 74nm, 75nm, 76nm, 77nm, 78nm, 79nm, 80nm, 81nm, 82nm, 83nm, 84nm, 85nm, 86nm, 87nm, 88nm, 89nm, 90nm, 91nm, 92nm, 93nm, 94nm, 95nm, 96nm, 97nm, 98nm, 99nm, 100nm, or a range consisting of any two values ​​in the range of 100nm-100nm.

[0043] In the embodiment of the present invention, the ratio of each component in the thermistor is within an appropriate range, which can help to further improve its over-protection effect and stability, and reduce its energy consumption.

[0044] In some embodiments of the present invention, the mass percentage of the composite thermal-sensitive material in the thermistor is 10%-25%. When the mass percentage of the thermal-sensitive ceramic material in the thermistor is within the above-mentioned suitable range, it can further help improve its over-protection effect.

[0045] Exemplarily, the mass percentage of the composite thermal-sensitive material in the thermistor may be, but is not limited to, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, or a range of values ​​consisting of any two values ​​in the range of 10%-25%.

[0046] In some embodiments of the present invention, the conductive filler content in the thermistor is 5%-10% by mass. When the conductive filler content in the thermistor is within the above-mentioned suitable range, the thermistor can have a lower resistance at room temperature, thereby reducing its energy consumption.

[0047] For example, the mass percentage of the conductive filler in the thermistor may be, but is not limited to, 5%, 6%, 7%, 8%, 9%, 10%, or a range consisting of any two values ​​within the range of 5%-10%.

[0048] In some embodiments of the present invention, the conductive filler may include at least one of carbon nanotubes, graphene, and carbon nanofibers.

[0049] In an embodiment of the present invention, the thermosensitive ceramic material may be any positive temperature coefficient ceramic material well known in the art, such as barium titanate particles, strontium titanate particles, and the like.

[0050] In some of the above embodiments, the particle size of the barium titanate particles is within an appropriate range, which can help improve the sensitivity of the composite thermosensitive ceramic. In some embodiments, the particle size r of the barium titanate particles is 10 μm-60 μm.

[0051] For example, the particle size r of the barium titanate particles can be, but is not limited to, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60μm, or a range consisting of any two values ​​in the range of 10μm-60μm.

[0052] A second aspect of the present invention provides a method for preparing a thermistor according to any embodiment of the first aspect of the present invention, comprising:

[0053] Dispersing raw materials of the nanoparticle film in a solvent to form a slurry, wherein the raw materials of the nanoparticle film include a shape memory material with thermal response;

[0054] The thermosensitive ceramic material having a positive temperature coefficient is immersed in the slurry, and after drying, a nanoparticle film is formed on the surface of the thermosensitive ceramic material to obtain a composite thermosensitive material;

[0055] The raw materials of the matrix, the conductor filler and the composite thermal-sensitive material are mixed, and the mixture is pressed and sintered to obtain the thermistor.

[0056] The third aspect of the present invention provides a temperature sensor, including the thermistor provided in the second aspect of the present invention as in any embodiment of the first aspect of the present invention or the thermistor prepared by the preparation method of any embodiment of the second aspect of the present invention.

[0057] The following embodiments describe the present disclosure in more detail, and these embodiments are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are by mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0058] Example 1

[0059] This embodiment provides a method for preparing a thermistor, the method comprising the following steps:

[0060] 100 mg of zirconium oxide nanoparticles and 1 mg of polyethylene were dispersed in 20 mL of ethanol to form a slurry;

[0061] 50 g of barium titanate thermosensitive ceramic material with an average particle size of 15 μm was immersed in the above slurry for 2 minutes, and then dried at 60° C. for 20 minutes. This was repeated three times (each time to form a thickness of about 5 nm), forming a nanoparticle film with a thickness of about 15 nm on the surface of the barium titanate thermosensitive ceramic material to obtain a composite thermosensitive material;

[0062] 425g of polyethylene, 25g of conductive filler single-walled carbon nanotubes and the above-mentioned composite thermosensitive material were mixed and granulated, and pressed under a pressure of 40MPa into a molded embryo with a diameter of about 1cm and a thickness of about 0.6cm;

[0063] The molded body was extruded at 600° C. for 5 hours and then sintered at 1400° C. for 5 hours to obtain a thermistor, wherein the mass percentage of the composite thermistor material in the thermistor was approximately 10%, and the mass percentage of the conductive filler single-walled carbon nanotubes in the thermistor was approximately 5%.

[0064] Example 2

[0065] The preparation method is similar to that of Example 1, except that the zirconium oxide nanoparticles are replaced by cerium oxide nanoparticles.

[0066] Example 3

[0067] The preparation method is similar to that of Example 1, except that the zirconium oxide nanoparticles are replaced by titanium oxide nanoparticles.

[0068] Example 4

[0069] The preparation method is similar to that of Example 1, except that the zirconium oxide nanoparticles are replaced by polyurethane and single-walled nanotubes, and the mass ratio of polyurethane to single-walled nanotubes is 10:1.

[0070] Example 5

[0071] The preparation method is similar to that of Example 1, except that:

[0072] (1) Dispersing 2000 mg of zirconium oxide nanoparticles and 50 mg of polyethylene in 30 mL of ethanol to form a slurry;

[0073] (2) Immerse 110 g of barium titanate thermosensitive ceramic material with an average particle size of 15 μm in the above slurry;

[0074] (3) The mass percentage of the composite thermal sensitive material in the thermistor is approximately 20%.

[0075] Example 6

[0076] The preparation method is similar to that of Example 1, except that:

[0077] (1) Dispersing 1000 mg of zirconium oxide nanoparticles and 10 mg of polyethylene in 25 mL of ethanol to form a slurry;

[0078] (2) 78 g of barium titanate thermosensitive ceramic material with an average particle size of 15 μm was immersed in the above slurry;

[0079] (3) The mass percentage of the composite thermal sensitive material in the thermistor is approximately 15%.

[0080] Example 7

[0081] The preparation method is similar to that of Example 1, except that the process is repeated 4 times, the thickness of the nanoparticle film is about 20 nm, and the mass percentage of the composite thermosensitive material in the thermistor is about 10.1%.

[0082] Example 8

[0083] The preparation method is similar to that of Example 1, except that the method is repeated 10 times, the thickness of the nanoparticle film is about 50 nm, and the mass percentage of the composite thermosensitive material in the thermistor is about 10.5%.

[0084] Example 9

[0085] The preparation method is similar to that of Example 1, except that the method is repeated 10 times, the thickness of the nanoparticle film is about 90 nm, and the mass percentage of the composite thermosensitive material in the thermistor is about 11%.

[0086] Comparative Example 1

[0087] The preparation method of the thermistor provided in this comparative example comprises the following steps:

[0088] 425g of polyethylene, 25g of conductive filler single-walled carbon nanotubes, and 50g of barium titanate thermosensitive ceramic material with an average particle size of 15μm were mixed and granulated, and pressed under a pressure of 40MPa into a molded body with a diameter of about 1cm and a thickness of about 0.6cm;

[0089] The molded body was extruded at 600° C. for 5 hours and then sintered at 1400° C. for 5 hours to obtain a thermistor, wherein the mass percentage of the composite thermistor material in the thermistor was approximately 10%, and the mass percentage of the conductive filler single-walled carbon nanotubes in the thermistor was approximately 5%.

[0090] Comparative Example 2

[0091] The preparation method is similar to that of Example 1, except that the zirconium oxide nanoparticles are replaced by silicon dioxide.

[0092] Comparative Example 3

[0093] This comparative example provides a method for preparing a thermistor, comprising:

[0094] 100 mg of zirconium oxide nanoparticles and 1 mg of polyethylene were dispersed in 20 mL of ethanol to form a slurry;

[0095] 50 g of barium titanate thermosensitive ceramic material with an average particle size of 15 μm, 425 g of polyethylene, and 25 g of single-walled carbon nanotubes as a conductive filler were mixed and granulated, and then pressed under a pressure of 40 MPa into a molded body with a diameter of about 1 cm and a thickness of about 0.6 cm;

[0096] The molded body was extruded at 600° C. for 5 hours, and then sintered at 1400° C. for 5 hours to obtain a thermistor semi-finished product, wherein the weight percentage of the barium titanate thermistor ceramic material in the thermistor semi-finished product was approximately 10%, and the weight percentage of the conductive filler single-walled carbon nanotubes in the thermistor semi-finished product was approximately 5%.

[0097] The semi-finished thermistor was immersed in the slurry for 2 minutes, dried at 60°C for 20 minutes, and repeated three times (each time to form a thickness of about 5 nm), forming a nanoparticle film with a thickness of about 15 nm on the surface of the semi-finished thermistor to obtain a finished thermistor.

[0098] Test section

[0099] (1) Particle size test of composite thermosensitive materials

[0100] The particle size r1 of the composite thermosensitive materials prepared in the above examples and comparative examples after returning to room temperature after passing the Curie point was measured by laser diffraction scattering method. The test results are shown in Table 1.

[0101] (2) Thickness test of nanoparticle film

[0102] The thickness of the nanoparticle film was measured by Raman spectroscopy (Raman) in the SEM. The composite thermosensitive material was fractured in liquid nitrogen to obtain the cross-section. The thickness of the nanoparticle film was then obtained by Raman microscopy (Raman Mapping) of the cross-section. The test results are shown in Table 1.

[0103] (3) Resistance value test

[0104] The samples prepared in the above examples and comparative examples were placed at room temperature (i.e., 25°C) and a voltage was applied to them. A multimeter (manufacturer: Hiki, model: RM3545) was used to measure the current and calculate the resistance R0. The samples were then held at 80°C for 5 minutes, cooled from 80°C to room temperature, and the same voltage was applied to them. The current was then measured using a multimeter. This process was repeated three times to calculate the resistance R3. Therefore, the resistance increase α is equal to (R3 - R0) / R0 × 100%. The test results are shown in Table 1.

[0105] Table 1 Test results of the embodiments and comparative examples

[0106]

[0107]

[0108] Note: A represents the mass percentage of the thermal sensitive material in the thermistor.

[0109] According to Table 1, a comparison of the test results of Examples 1-9 and Comparative Examples 1-2 shows that the present invention provides a nanoparticle film on the surface of the thermosensitive ceramic material, and the nanoparticle film includes a thermally responsive shape memory material. This allows the nanoparticle film to have a shape memory function. When the thermistor is overprotected, it helps to reduce the increase in particle size of the thermosensitive ceramic material, which can also be understood as the increase in volume. This reduces the probability of the conductive network formed by the conductive filler being disassembled, thereby helping the resistance value of the thermistor to approach the original value before overprotection after overprotection, thereby improving its stability.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A thermistor having a nanoparticle film, characterized in that: include: matrix; Conductive fillers are dispersed in the matrix and overlap with each other to form a conductive network; A composite thermosensitive material is dispersed in the matrix, the composite thermosensitive material comprising a thermosensitive ceramic material having a positive temperature coefficient and a nanoparticle film disposed on a surface of the thermosensitive ceramic material, the nanoparticle film comprising a shape memory material having a thermal response; The shape memory material includes shape memory ceramics and / or shape memory polymers; The method for preparing the thermistor comprises: dispersing raw materials of a nanoparticle film in a solvent to form a slurry, wherein the raw materials of the nanoparticle film include a shape memory material having a thermal response; impregnating a thermosensitive ceramic material having a positive temperature coefficient into the slurry, and forming a nanoparticle film on the surface of the thermosensitive ceramic material after drying to obtain a composite thermosensitive material; The raw material of the matrix, the conductor filler and the composite thermal-sensitive material are mixed, and the mixture is pressed and sintered to obtain the thermistor.

2. The thermistor according to claim 1, wherein The nanoparticle film further includes a conductive nanomaterial, and the mass ratio of the conductive nanomaterial to the shape memory material is 1:(10-20).

3. The thermistor according to claim 2, wherein: The shape memory material includes shape memory ceramics, and the shape memory ceramics include at least one of zirconium oxide nanoparticles, cerium oxide nanoparticles, and titanium oxide nanoparticles.

4. The thermistor according to claim 3, wherein: The shape memory material includes a shape memory polymer, and the shape memory polymer includes at least one of polyurethane, polylactone, polystyrene, and epoxy resin.

5. The thermistor according to claim 2, wherein: The conductive nanomaterial includes one or more of nickel nanoparticles, single-walled carbon nanotubes, multi-walled carbon nanotubes and iron nanoparticles.

6. The thermistor according to claim 1, wherein: The thickness of the nanoparticle film is 10 nm to 100 nm.

7. The thermistor according to claim 1, wherein The mass percentage of the composite thermosensitive material in the thermistor is 10%-25%.

8. The thermistor according to claim 1, wherein: The conductive filler has a mass percentage of 5%-10% in the thermistor.

9. A method for preparing a thermistor according to any one of claims 1 to 8, characterized in that: include: Dispersing a raw material of a nanoparticle film in a solvent to form a slurry, wherein the raw material of the nanoparticle film includes a shape memory material having a thermal response; impregnating a thermosensitive ceramic material having a positive temperature coefficient into the slurry, and forming a nanoparticle film on the surface of the thermosensitive ceramic material after drying to obtain a composite thermosensitive material; The raw material of the matrix, the conductor filler and the composite thermal-sensitive material are mixed, and the mixture is pressed and sintered to obtain the thermistor.

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