A barium titanate-based thermistor and its preparation method and application

Abstract

The present invention relates to the technical field of thermistors, and specifically provides a barium titanate-based thermistor, a preparation method thereof and an application thereof, which include a first electrode, a second electrode and a thermosensitive ceramic layer, and the second electrode is disposed opposite to the first electrode; the thermosensitive ceramic layer is disposed between the first electrode and the second electrode, and the thermosensitive ceramic layer includes a matrix and thermosensitive ceramic particles dispersed in the matrix, and the thermosensitive ceramic particles include barium titanate particles and a conductive layer coated on the surface of the barium titanate particles, and the coating rate of the conductive layer is 20%-50%; wherein, the change rate of the resistance value of the barium titanate-based thermistor at temperature T to the resistance value of the barium titanate-based thermistor at 25°C is 0.01 Ω / °C - 0.1 Ω / °C, wherein, 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles. The barium titanate-based thermistor can help reduce the power consumption of the components using it.

Description

Technical Field

[0001] The invention relates to the technical field of thermistors, and in particular to a barium titanate-based thermistor and a preparation method and application thereof. Background Art

[0002] Thermistor is a sensor resistor whose resistance value changes with temperature. According to the temperature coefficient, it is divided into positive temperature coefficient thermistor (PTC thermistor, i.e. Positive Temperature Coefficient thermistor) and negative temperature coefficient thermistor (NTC thermistor, i.e. Negative Temperature Coefficient thermistor). The resistance value of the positive temperature coefficient thermistor increases with the increase of temperature, and the resistance value of the negative temperature coefficient thermistor decreases with the increase of temperature. Among them, in actual application, the resistance of PTC at normal temperature can be maintained at an extremely low value, so that the components using it can operate normally. However, when the above-mentioned components using PTC have the phenomenon of too high current or too high temperature, the resistance value of PTC will instantly increase to a certain high resistance value to reduce the excessive current, so as to achieve the purpose of protecting the components.

[0003] However, in the related art, the resistance value of PTC increases rapidly with the increase of temperature. Although the temperature does not trigger its resistance value to increase to a certain high resistance value instantly, the rapid increase of resistance value will cause the power consumption of the components using it to increase significantly.

[0004] Therefore, there is an urgent need to develop a barium titanate-based thermistor that can help reduce power consumption and a preparation method and application thereof. Summary of the invention

[0005] The present invention provides a barium titanate-based thermistor and a preparation method and application thereof. The barium titanate-based thermistor can help reduce the power consumption of components using the thermistor.

[0006] The first aspect of the present invention provides a barium titanate-based thermistor, comprising:

[0007] a first electrode;

[0008] a second electrode, arranged opposite to the first electrode;

[0009] A thermosensitive ceramic layer is disposed between the first electrode and the second electrode, the thermosensitive ceramic layer comprises a matrix and thermosensitive ceramic particles dispersed in the matrix, the thermosensitive ceramic particles comprise barium titanate particles and a conductive layer coated on the surface of the barium titanate particles, and the coating rate of the conductive layer is 20%-50%;

[0010] Among them, the change rate of the resistance value of the barium titanate-based thermistor at temperature T to the resistance value of the barium titanate-based thermistor at 25°C is 0.01 Ω / °C - 0.1 Ω / °C, where 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles.

[0011] According to any of the foregoing embodiments of the present invention, the following relationship is satisfied between the particle size r of the barium titanate particles and the thickness d of the conductive layer: 10 ≤ r / d ≤ 5000.

[0012] According to any of the foregoing embodiments of the present invention, the particle size r of the barium titanate particles is 5 µm - 40 µm, and the thickness d of the conductive layer is 0.01 µm - 0.1 µm.

[0013] According to any of the foregoing embodiments of the present invention, the conductive layer includes conductive oxides and nitrides.

[0014] According to any of the foregoing embodiments of the present invention, the conductive layer includes conductive oxides, and the mass ratio of the oxides to the barium titanate particles is 1:(5 - 10);

[0015] And / or, the conductive layer includes conductive nitrides, and the mass ratio of the nitrides to the barium titanate particles is 1:(10 - 20).

[0016] According to any of the foregoing embodiments of the present invention, the oxides include at least one of aluminum oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, indium tin oxide, indium zinc oxide, gallium zinc oxide, aluminum zinc oxide, or a mixture thereof.

[0017] According to any of the foregoing embodiments of the present invention, the mass proportion of the thermosensitive ceramic particles in the thermosensitive ceramic layer is 75% - 90%.

[0018] According to any of the foregoing embodiments of the present invention, the substrate includes a crystalline polymer.

[0019] The second aspect of the present invention provides a method for preparing a barium titanate-based thermistor according to any of the embodiments of the first aspect of the present invention, including:

[0020] Providing a first electrode and a second electrode;

[0021] Performing a coating treatment on the barium titanate particles to form a conductive layer on the surface of the barium titanate particles, obtaining thermosensitive ceramic particles, where the coating rate of the conductive layer is 20% - 50%;

[0022] Mixing and granulating the thermosensitive ceramic particles with the raw materials of the substrate, and forming a thermosensitive ceramic layer after pressing and sintering;

[0023] Place the thermosensitive ceramic layer between the first electrode and the second electrode to obtain the barium titanate-based thermistor;

[0024] Among them, the change rate of the resistance value of the barium titanate-based thermistor at temperature T to the resistance value of the barium titanate-based thermistor at 25°C is 0.01 Ω / °C - 0.1 Ω / °C, where 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles.

[0025] The third aspect of the present invention provides a temperature sensor, including the barium titanate-based thermistor according to any one of the embodiments of the first aspect of the present invention or the barium titanate-based thermistor prepared by the preparation method according to any one of the embodiments of the second aspect of the present invention.

[0026] The barium titanate-based thermistor, its preparation method and application provided by the present invention. The barium titanate-based thermistor includes a first electrode, a second electrode and a thermosensitive ceramic layer. The second electrode is disposed opposite to the first electrode; the thermosensitive ceramic layer is disposed between the first electrode and the second electrode. The thermosensitive ceramic layer includes a matrix and thermosensitive ceramic particles dispersed in the matrix. The thermosensitive ceramic particles include barium titanate particles and a conductive layer coated on the surface of the barium titanate particles, and the coating rate of the conductive layer is 20% - 50%; among them, the change rate of the resistance value of the barium titanate-based thermistor at temperature T to the resistance value of the barium titanate-based thermistor at 25°C is 0.01 Ω / °C - 0.1 Ω / °C, where 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles. The above technical solution coats a conductive layer on the surface of the thermosensitive ceramic particles. The coating rate of the conductive layer is in the range of 20% - 50%, and the change rate of the resistance value of the barium titanate-based thermistor in the T temperature range to the resistance value of the barium titanate-based thermistor at 25°C is 0.01 Ω / °C - 0.1 Ω / °C, so as to reduce the resistance change of the thermistor in the T range, thereby reducing the power consumption of the component applying the thermistor.

[0027] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are specifically listed below. Detailed Embodiments

[0028] The "range" disclosed by the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range.

[0029] Unless otherwise specified, the terms used in the present invention have the well-known meanings commonly understood by those skilled in the art.

[0030] Unless otherwise specified, the numerical values of the various parameters mentioned in the present invention can be measured by various commonly used test methods in the art. For example, they can be measured according to the test methods given in the embodiments of the present invention.

[0031] The first aspect of the present invention provides a barium titanate-based thermistor, which includes a first electrode, a second electrode and a thermosensitive ceramic layer. The second electrode is disposed opposite to the first electrode; the thermosensitive ceramic layer is disposed between the first electrode and the second electrode. The thermosensitive ceramic layer includes a matrix and thermosensitive ceramic particles dispersed in the matrix. The thermosensitive ceramic particles include barium titanate particles and a conductive layer coated on the surface of the barium titanate particles, and the coating rate of the conductive layer is 20%-50%; wherein, the change rate of the resistance value of the barium titanate-based thermistor at temperature T to the resistance value of the barium titanate-based thermistor at 25°C is 0.01Ω / °C - 0.1Ω / °C, where 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles.

[0032] In this article, the term "coating rate" refers to the percentage of the total area of the conductive layer to the outer surface area of the barium titanate particles, and it can be tested by the well-known test methods and test instruments in the art. For example, a scanning electron microscope (SEM) can be used to observe the microscopic morphology of the thermosensitive ceramic particles and the barium titanate particles, so as to calculate the coating rate.

[0033] In this article, the resistance value can be tested by the well-known test methods and test instruments in the art. For example, the sample to be tested is placed at room temperature (i.e., 25°C), and a voltage is applied to the above-mentioned sample to be tested. Then, a multimeter (manufacturer: HIOKI, model: RM3545) is used to measure its current value, and the resistance value R0 is calculated; then the above-mentioned sample is placed at temperature T, and after applying the same voltage to the sample, a multimeter is used to measure its current value, and the resistance value R is calculated. Therefore, the change rate of the resistance value is equal to (R - R0) / (T - 25°C).

[0034] The barium titanate-based thermistor provided by the present invention is formed by coating a conductive layer on the surface of a thermistor ceramic particle, wherein the coating rate of the conductive layer is in the range of 20%-50%, and the resistance value of the barium titanate-based thermistor in the temperature range T and the resistance value of the barium titanate-based thermistor at 25° C. change rate is 0.01Ω / ° C.-0.1Ω / ° C., so that the resistance change of the thermistor in the temperature range T can be reduced, thereby reducing the power consumption of the component using the thermistor.

[0035] In some embodiments, the material composition of the first electrode and the second electrode can be a material with high conductivity without causing chemical changes. Exemplarily, the material of the electrode can include any one of copper, aluminum, titanium, zinc, stainless steel, silver, nickel, iron, or an alloy thereof. The present invention does not make any characteristic restrictions here.

[0036] In the thermistor ceramic particles in the above embodiment, the ratio of the particle size of the barium titanate particles to the thickness of the conductive layer is within a suitable range, which can effectively reduce the change rate of the thermistor in the T temperature range.

[0037] In some embodiments, the particle size r of the barium titanate particles and the thickness d of the conductive layer satisfy: 10≤r / d≤5000.

[0038] The particle size refers to the D50 particle size, that is, the particle size corresponding to when the cumulative particle size distribution percentage reaches 50%, which can be obtained by testing using testing methods and testing equipment well known in the art, for example, the D50 particle size in the particle size distribution can be measured by laser diffraction scattering method.

[0039] The thickness of the conductive layer refers to the distance between the side of the conductive layer close to the surface of the barium titanate particle and the side of the conductive layer away from the surface of the barium titanate particle along the radial direction of the barium titanate particle. The thickness can be obtained by SEM, EDS, TEM, XPS and other tests.

[0040] , 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 1000, 1050, 1100, 1150, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000 or a range of values ​​consisting of any two values ​​in the range of 10-5000.

[0041] In the embodiment of the present invention, the particle size of the barium titanate particles is within a suitable range, which can help improve the sensitivity of the thermistor ceramic layer. The thickness of the conductive layer is within a suitable range, which can not only improve the structural stability of the thermistor ceramic particles, but also further reduce the resistance change rate of the thermistor ceramic particles in the T temperature range.

[0042] In some embodiments, the particle size r of the barium titanate particles is 5 µm-40 µm, and the thickness d of the conductive layer is 0.01 µm-0.1 µm.

[0043] For example, the particle size r of the barium titanate particles can be, but is not limited to, 5µm, 6µm, 7µm, 8µm, 9µm, 10µm, 11µm, 12µm, 13µm, 14µm, 15µm, 16µm, 17µm, 18µm, 19µm, 20µm, 21µm, 22µm, 23µm, 24µm, 25µm, 26µm, 27µm, 28µm. , 29µm, 30µm, 31µm, 32µm, 33µm, 34µm, 35µm, 36µm, 37µm, 38µm, 39µm, 40µm, 41µm, 42µm, 43µm, 44µm, 45µm, 46µm, 47µm, 48µm, 49µm, 50µm or a range consisting of any two values ​​in the range of 5µm-40µm.

[0044] The thickness d of the conductive layer may be, but is not limited to, 0.01µm, 0.015µm, 0.02µm, 0.025µm, 0.03µm, 0.035µm, 0.04µm, 0.045µm, 0.05µm, 0.055µm, 0.06µm, 0.065µm, 0.07µm, 0.075µm, 0.08µm, 0.085µm, 0.09µm, 0.095µm, 0.1µm or a range consisting of any two of the above values.

[0045] In the embodiment of the present invention, the conductive layer is made of a suitable material, which can help to further maintain the resistance value of the thermistor within the temperature range of T, thereby reducing its resistance change within the temperature range of T, thereby reducing the power consumption of the components using it.

[0046] In some embodiments, the conductive layer includes conductive oxides and nitrides. The conductive layer formed by the conductive oxides and nitrides can maintain the rate of change of the resistance value of the thermistor within the temperature range T within a smaller range, thereby helping to further reduce the power consumption of the components using it. In addition, the rate of change of the resistance value of the thermistor within the temperature range T can be further reduced by adjusting the mass ratio of the oxide or nitride to the barium titanate particles in the conductive layer.

[0047] In some optional embodiments of the present invention, the conductive layer includes an oxide having conductivity, and the mass ratio of the oxide to the barium titanate particles is 1:(5-10).

[0048] Illustratively, the mass ratio of the oxide to the barium titanate particles may be, but is not limited to, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, or 1:10.

[0049] In some of the above embodiments, the conductive layer may include a nitride having conductivity, and the mass ratio of the nitride to the barium titanate particles is 1:(10-20).

[0050] Exemplarily, the mass ratio of nitride to barium titanate particles can be, but is not limited to, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, 1:15.5, 1:16, 1:16.5, 1:17, 1:17.5, 1:18, 1:18.5, 1:19, 1:19.5, 1:20.

[0051] In some optional embodiments, the conductive layer may include oxide and nitride, and the mass ratio of oxide, nitride and barium titanate particles is 2:1:(10-20).

[0052] In the above embodiments, the oxide may include a metal oxide, such as aluminum oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, indium tin oxide, indium zinc oxide, gallium zinc oxide, aluminum zinc oxide, or a mixture thereof. The nitride includes a metal nitride, such as titanium nitride.

[0053] In an embodiment of the present invention, the mass ratio of the thermosensitive ceramic particles in the thermosensitive ceramic layer is within a suitable range, which can help to improve its overprotection effect.

[0054] In some embodiments, the mass proportion of the thermosensitive ceramic particles in the thermosensitive ceramic layer is 75%-90%.

[0055] In some embodiments, the matrix includes a crystalline high molecular polymer, such as polyethylene, polypropylene, polyfluoroolefin, and the like.

[0056] In some embodiments, the Curie temperature Tc of the thermosensitive ceramic particles is 120°C-200°C.

[0057] The second aspect of the present invention provides a method for preparing a barium titanate-based thermistor according to any embodiment of the first aspect of the present invention, comprising:

[0058] providing a first electrode and a second electrode;

[0059] The barium titanate particles are coated to form a conductive layer on the surface of the barium titanate particles, and thermosensitive ceramic particles are obtained, wherein the coating rate of the conductive layer is 20%-50%;

[0060] The thermosensitive ceramic particles and the raw materials of the substrate are mixed and granulated, and a thermosensitive ceramic layer is formed after pressing and sintering;

[0061] The thermosensitive ceramic layer is disposed between the first electrode and the second electrode to obtain a barium titanate-based thermistor, wherein the change rate of the resistance value of the barium titanate-based thermistor at temperature T to the resistance value of the barium titanate-based thermistor at 25 °C is 0.01 Ω / °C - 0.1 Ω / °C, wherein 25 °C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles.

[0062] The third aspect of the present invention provides a temperature sensor, including a barium titanate-based thermistor according to any one of the embodiments of the first aspect of the present invention or a barium titanate-based thermistor prepared by the preparation method of any one of the embodiments of the second aspect of the present invention.

[0063] The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the embodiments are all commercially available.

[0064] Example 1

[0065] This embodiment provides a preparation method of a barium titanate-based thermistor, and the preparation method includes the following steps:

[0066] (1) Provide a first electrode and a second electrode, wherein both the first electrode and the second electrode are aluminum electrodes;

[0067] (2) Mix barium titanate particles with a particle size r of 20 µm and alumina (Al2O3) in a mass ratio of 6:1, and perform sintering treatment in an atmosphere with an oxygen concentration of ≥99.9%. The temperature of the sintering treatment is 700 °C. After sintering for 3 h, it is cooled to room temperature to obtain thermosensitive ceramic particles, wherein the coating rate of the conductive layer formed by alumina is 20%, the thickness d is 0.01 µm, and Tc is 120 °C;

[0068] (3) The above-mentioned thermosensitive ceramic particles and the binder polyethylene are mixed and granulated in a mass ratio of 10:1, and pressed at a pressure of 20 MPa into a thermosensitive ceramic embryo with a diameter of 0.5 cm and a thickness of 0.4 cm;

[0069] (4) extruding the thermosensitive ceramic body at 500° C. for 4 hours, and then sintering at 1200° C. for 4 hours to obtain a thermosensitive ceramic layer;

[0070] (5) A pair of electrodes, namely, a first electrode and a second electrode, are formed on the front and back surfaces of the thermosensitive ceramic layer.

[0071] Example 2

[0072] The preparation method is similar to that of Example 1, except that in step (2), the sintering time is 4 h and the coverage of the conductive layer is 40%.

[0073] Example 3

[0074] The preparation method is similar to that of Example 1, except that in step (2), the sintering time is 5 h and the coverage of the conductive layer is 50%.

[0075] Example 4

[0076] The preparation method is similar to that of Example 1, except that the particle size r of the barium titanate particles is 10 μm, and the thickness d of the conductive layer is 0.05 μm.

[0077] Example 5

[0078] The preparation method is similar to that of Example 1, except that the particle size r of the barium titanate particles is 5 μm, and the thickness d of the conductive layer is 0.01 μm.

[0079] Example 6

[0080] The preparation method is similar to that of Example 1, except that the barium titanate particles and Al2O3 are mixed in a mass ratio of 8:1.

[0081] Example 7

[0082] The preparation method is similar to that of Example 1, except that the barium titanate particles and Al2O3 are mixed in a mass ratio of 10:1.

[0083] Example 8

[0084] The preparation method is similar to that of Example 1, except that barium titanate particles and zinc oxide (ZnO) are mixed in a mass ratio of 6:1.

[0085] Example 9

[0086] The preparation method is similar to that of Example 1, except that barium titanate particles and indium zinc oxide (IZO) are mixed in a mass ratio of 6:1.

[0087] Example 10

[0088] The preparation method is similar to that of Example 1, except that barium titanate particles, Al2O3 and titanium nitride (TiN) are mixed in a mass ratio of 10:2:1 and sintered in an atmosphere of nitrogen with an oxygen concentration of ≥99.9%.

[0089] Comparative Example 1

[0090] The preparation method is similar to that of Example 1, except that in step (2), the sintering time is 10 h and the coverage of the conductive layer is 70%.

[0091] Comparative Example 2

[0092] The preparation method is similar to that of Example 1, except that in step (2), the sintering time is 1 h and the coverage of the conductive layer is 15%.

[0093] Comparative Example 3

[0094] The preparation method is similar to that of Example 1, except that the conductive layer is replaced by a conductive filler, that is, barium titanate particles and aluminum oxide particles are mixed without coating treatment.

[0095] Test Section

[0096] (1) Particle size test of barium titanate particles

[0097] The D50 particle size in the particle size distribution was measured by laser diffraction scattering method, and the test results are shown in Table 1.

[0098] (2) Conductive layer thickness test

[0099] The thickness of the conductive layer is tested by Raman spectrometer (Raman) in SEM. The thermosensitive ceramic particles are fractured by liquid nitrogen to obtain the cross-section. The thickness of the conductive layer is then obtained by Raman microscopy (Raman Mapping) of the cross-section. The test results are shown in Table 1.

[0100] (3) Coverage test

[0101] The thermosensitive ceramic particles prepared in the embodiment and the comparative example were ultrasonically dispersed in an ethanol solution to form a mixed slurry, and then the mixed slurry was coated on a silicon wafer, and the silicon wafer was subjected to a SEM test. The thermosensitive ceramic particles at 150 different positions were selected from the test images using AUTOCAD software, the uncoated area on the surface of each particle was marked at a high magnification, and the percentage of the coverage was counted.

[0102] (4) Resistance value change rate test

[0103] The samples prepared in the above embodiments and comparative examples were placed at room temperature (i.e., 25°C), and voltage was applied to the samples. A multimeter (brand: HIOKI, model: RM3545) was used to measure the current value, and the resistance value R0 was calculated. The samples were placed at 80°C, and after the same voltage was applied to the samples, a multimeter was used to measure the current value, and the resistance value R was calculated. Therefore, the change rate α of the resistance value is equal to (R-R0) / 55°C. The test results are shown in Table 1.

[0104] Table 1 Test results of embodiments and comparative examples

[0105]

[0106] According to Table 1, by comparing the test results of Examples 1-10 and Comparative Examples 1-3, it can be seen that the present invention coats the surface of the thermistor ceramic particles with a conductive layer, the coverage rate of the conductive layer is in the range of 20%-50%, and the resistance value of the barium titanate-based thermistor in the temperature range T and the resistance value of the barium titanate-based thermistor at 25°C change rate are 0.01Ω / °C-0.1Ω / °C, so that the resistance change of the thermistor in the T range can be reduced, thereby reducing the power consumption of the component using the thermistor.

[0107] 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment 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 barium titanate based thermistor, characterized in that: Comprising: A first electrode; A second electrode, oppositely arranged with respect to the first electrode; A thermosensitive ceramic layer, disposed between the first electrode and the second electrode, the thermosensitive ceramic layer comprising a matrix and thermosensitive ceramic particles dispersed in the matrix, the thermosensitive ceramic particles comprising barium titanate particles and a conductive layer coated on the surface of the barium titanate particles, and the coating rate of the conductive layer being 20% - 50%; Wherein, the rate of change of the resistance value of the barium titanate-based thermistor from temperature T to 25°C is 0.01 Ω / °C - 0.1 Ω / °C, wherein 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles; The following is satisfied between the particle size r of the barium titanate particles and the thickness d of the conductive layer: 10 ≤ r / d ≤ 5000; The particle size r of the barium titanate particles is 5 µm - 40 µm, and the thickness d of the conductive layer is 0.01 µm - 0.1 µm; The mass proportion of the thermosensitive ceramic particles in the thermosensitive ceramic layer is 75% - 90%.

2. The barium titanate-based thermistor according to claim 1, characterized in that: The conductive layer comprises conductive oxides and nitrides.

3. The barium titanate-based thermistor according to claim 1, characterized in that: The conductive layer comprises conductive oxides, and the mass ratio of the oxides to the barium titanate particles is 1:(5 - 10); And / or, the conductive layer comprises conductive nitrides, and the mass ratio of the nitrides to the barium titanate particles is 1:(10 - 20).

4. The barium titanate-based thermistor according to claim 2 or 3, characterized in that: The oxides comprise at least one of aluminum oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, indium tin oxide, indium zinc oxide, gallium zinc oxide, aluminum zinc oxide or a mixture thereof.

5. The barium titanate-based thermistor according to claim 1, characterized in that: The matrix comprises a crystalline polymer.

6. A method for preparing a barium titanate-based thermistor as claimed in any one of claims 1 to 5, characterized in that: Comprising: Providing a first electrode and a second electrode; Performing a coating treatment on the barium titanate particles to form a conductive layer on the surface of the barium titanate particles, obtaining thermosensitive ceramic particles, wherein the coating rate of the conductive layer is 20% - 50%; Mixing and granulating the raw materials of the thermosensitive ceramic particles and the matrix, and forming a thermosensitive ceramic layer after pressing and sintering; Disposing the thermosensitive ceramic layer between the first electrode and the second electrode to obtain the barium titanate-based thermistor; Wherein, the rate of change of the resistance value of the barium titanate-based thermistor at temperature T with respect to the resistance value of the barium titanate-based thermistor at 25°C is 0.01 Ω / °C - 0.1 Ω / °C, wherein 25°C < T ≤ Tc, and Tc represents the Curie temperature of the thermosensitive ceramic particles.

7. A temperature sensor, characterized in that: Comprising the barium titanate-based thermistor according to any one of claims 1 - 5 or the barium titanate-based thermistor prepared by the preparation method according to claim 6.

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