SnO2 / RGO composite heat-sensitive material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of materials, in particular to a SnO2 / RGO composite heat-sensitive material as well as a preparation method and application thereof, and the preparation method comprises the step of performing one-step solvothermal reaction on reactants and a dispersing agent to prepare the SnO2 / RGO composite heat-sensitive material. According to the preparation method disclosed by the embodiment of the invention, RGO is doped into SnO2, and the introduction of RGO provides a high-mobility conductive network for the composite material, so that the linear response of the composite material as a temperature sensor is improved, the response time is shortened, and the performance of the SnO2 / RGO composite heat-sensitive material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a SnO2 / RGO composite thermosensitive material and a preparation method and application thereof. BACKGROUND

[0002] Thermistors are a common temperature-sensitive device, and thermistors are generally divided into negative temperature coefficient thermistors (NTC) and positive temperature coefficient thermistors (PTC). As an important temperature sensing element, negative temperature coefficient (NTC) thermistors are widely used in new energy vehicle battery management, industrial equipment temperature control, medical instruments and consumer electronics, etc. The core function is to realize high-precision temperature monitoring and control through the characteristic of resistance change with temperature. However, the traditional NTC thermistor material (such as manganese-cobalt-nickel oxide) has problems such as complex preparation process and slow response time in actual application. However, it has been widely concerned in the temperature sensing field due to its advantages in adapting to flexible and miniaturized design requirements.

[0003] Negative temperature coefficient thermistors (NTC) are a temperature sensing element made of semiconductor materials, which react to the phenomenon of temperature rise through the trend of resistivity drop. For example, pure SnO2 material is a metal semiconductor material with negative temperature coefficient (NTC) effect, but single SnO2 material has problems such as nonlinearity and slow response time in the application field of thermistors, and the nonlinearity problem will significantly increase the complexity of measurement and calibration in the subsequent application process.

[0004] Therefore, it is of great significance to develop a thermosensitive material with simple preparation process, high sensitivity, high linearity, fast response and good stability for improving the effective application of thermistors. SUMMARY

[0005] In order to solve the problems of non-linear response and slow response time of single SnO2 material in temperature sensing in the above technical problems, the present application provides a SnO2 / RGO composite thermosensitive material and a preparation method and application thereof.

[0006] As an aspect, the present application provides a preparation method of a SnO2 / RGO composite thermosensitive material, which carries out one-step solvothermal reaction on reactants and dispersants to prepare the SnO2 / RGO composite thermosensitive material.

[0007] In some embodiments, the reactants include stannous chloride and oxalic acid.

[0008] In some embodiments, the dispersant is polyvinylpyrrolidone.

[0009] In some embodiments, the mass ratio of stannous chloride, oxalic acid and polyvinylpyrrolidone in the solvothermal reaction is (0.116~58):(2.15~1075):(1.1~550).

[0010] In some embodiments, the reaction temperature of the solvothermal reaction is 180℃; and / or, the reaction time is 12h.

[0011] In some embodiments, the content of RGO in the SnO2 / RGO composite thermosensitive material is 2.5~20wt%.

[0012] As another aspect, the present application provides a SnO2 / RGO composite thermosensitive material prepared by the preparation method as described above.

[0013] As still another aspect, the present application provides an application of the SnO2 / RGO composite thermosensitive material as described above in preparing a temperature sensor element.

[0014] In some embodiments, the preparation method of the temperature sensor element comprises: mixing the SnO2 / RGO composite thermosensitive material with a PVDF / NMP solution to prepare a SnO2 / RGO composite thermosensitive material slurry; and dropping the SnO2 / RGO composite thermosensitive material slurry on a sensor substrate, and sequentially performing drying and packaging to obtain the temperature sensor element.

[0015] In some embodiments, in the preparation method of the temperature sensor element, the concentration of the PVDF / NMP solution is 0.016g / mL~0.02g / mL.

[0016] The technical solution provided by the present application has the following advantages: The preparation method of the SnO2 / RGO composite thermosensitive material of the present application uses stannous chloride dihydrate and oxalic acid as reactants, adopts one-step hydrothermal method combined with dispersant polyvinylpyrrolidone to regulate, uniformly loads SnO2 particles on the surface of RGO, and forms C-O-Sn chemical interface bonding, realizes efficient compounding of SnO2 and RGO, and significantly improves the structural stability and charge transport efficiency of the material.

[0017] The preparation method of the SnO2 / RGO composite thermosensitive material of the present application adopts a one-step solvothermal method to prepare the SnO2 / RGO composite thermosensitive material, which is simple in process and low in cost. The linearity of the prepared SnO2 / RGO composite thermosensitive material is improved, and the SnO2 / RGO composite thermosensitive material also has good repeatability and stability. Specifically, SnO2 is an n-type semiconductor, and when the temperature increases, the concentration of intrinsic carriers of SnO2 increases, and the local conductivity is enhanced. The incorporation of RGO forms a long-range conductive path with its unique two-dimensional sheet structure, so that the carriers can quickly migrate, thereby improving the temperature sensing performance of SnO2. Therefore, the incorporation of RGO improves the linearity of the SnO2 / RGO composite thermosensitive material, and the SnO2 / RGO composite thermosensitive material also has good repeatability and stability. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings incorporated into the specification and constituting a part of the specification show embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, other drawings can also be obtained by those skilled in the art without creative labor based on these drawings.

[0020] Figure 1 XRD spectrum of the SnO2 / RGO composite thermosensitive material prepared in the present application examples 1~5; Figure 2 SEM image of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2; Figure 3 XPS image of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2; Figure 4 Sensitivity and linearity graph of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2 at 10~100℃; Figure 5 Hysteresis graph of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2; Figure 6 Response time graph of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2 at 25~70℃; Figure 7 Sixth repeatability graph of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2 at 10~100℃; Figure 8 Stability graph of the SnO2 / RGO composite thermosensitive material prepared in the present application example 2 within 30 days. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the schemes of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0022] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other manners different from those described herein; obviously, the embodiments described in the specification are only a part of the embodiments of the present application, and not all the embodiments.

[0023] According to an embodiment of the present application, a preparation method of SnO2 / RGO composite thermal sensitive material is provided, which uses stannous chloride dihydrate and oxalic acid as reactants, polyvinylpyrrolidone as dispersant, and deionized water as solvent, and adopts one-step solvothermal method to prepare SnO2 / RGO composite thermal sensitive material.

[0024] In some embodiments of the present application, the preparation method of SnO2 / RGO (Reduced Graphene Oxide) composite thermal sensitive material specifically includes the following steps: stannous chloride dihydrate is dissolved in deionized water, and then oxalic acid is added, and stirring is performed on a magnetic stirrer; then the dispersant polyvinylpyrrolidone is added, and after the solution is stirred to be clear, a certain mass of graphite oxide (GO) is added, and the SnO2 / RGO composite thermal sensitive material is obtained by one-step solvothermal method after uniform stirring.

[0025] In some embodiments of the present application, in the steps of the preparation method of SnO2 / RGO composite thermal sensitive material, the mass of stannous chloride dihydrate is 0.116 g, the mass of oxalic acid is 2.15 g, the mass of polyvinylpyrrolidone is 1.1 g, and GO with a mass of 1.92 mg, 3.96 mg, 8.4 mg, 13.08 mg and 18.6 mg is added respectively, so as to obtain SnO2 / RGO composite thermal sensitive material with different RGO contents. In the prepared SnO2 / RGO composite thermal sensitive material, the mass percentage content of RGO is 2.5wt%-20wt%.

[0026] In some embodiments of the present application, in the steps of the preparation method of SnO2 / RGO composite thermal sensitive material, the mixed solution of stannous chloride dihydrate, oxalic acid and polyvinylpyrrolidone is stirred and dissolved to be uniform and clear.

[0027] In some embodiments of the present application, in the steps of the preparation method of SnO2 / RGO composite thermal sensitive material, the reaction temperature of one-step solvothermal method is 180℃, and the reaction time is 12h.

[0028] In some embodiments of the present application, in the step of the preparation method of the SnO2 / RGO composite thermosensitive material, the product obtained after the reaction is centrifuged, washed with ionized water and anhydrous ethanol in sequence, and the final product is dried.

[0029] In some embodiments of the present application, the content of RGO in the SnO2 / RGO composite thermosensitive material obtained by the preparation method of the SnO2 / RGO composite thermosensitive material is 2.5-20wt%, more preferably 5wt%, and the composite material has the optimal comprehensive performance (sensitivity of-0.766% / ℃, linearity of 99.64%, and hysteresis of 1.74%).

[0030] According to an embodiment of the present application, a method for obtaining a temperature sensor element by using the above SnO2 / RGO composite thermosensitive material is provided. The preparation method of the temperature sensor element specifically comprises the following steps: mixing the SnO2 / RGO composite thermosensitive material with a PVDF / NMP (polyvinylidene fluoride / methyl pyrrolidone) solution to form a SnO2 / RGO composite thermosensitive material slurry; drop-coating the SnO2 / RGO composite thermosensitive material slurry on a selected sensor substrate, drying, and then packaging to obtain a temperature sensor element. N - methyl pyrrolidone) solution to form a SnO2 / RGO composite thermosensitive material slurry; drop-coating the SnO2 / RGO composite thermosensitive material slurry on a selected sensor substrate, drying, and then packaging to obtain a temperature sensor element.

[0031] The technical solutions of the present application are further described and explained below through specific embodiments.

[0032] The reagents used in the following examples are commercially available reagents.

[0033] Preparation of SnO2 / RGO composite thermosensitive material Example 1 Preparation of SnO2 / RGO (2.5wt%) composite thermosensitive material S1. Accurately weigh 0.1160g of stannous chloride dihydrate (SnCl2·2H2O) and 2.15g of oxalic acid (H2C2O4·2H2O), and stir and disperse them in 60mL of deionized water until the solution becomes clear; S2. Add 1.1g of dispersant polyvinylpyrrolidone (PVP-K30) to the solution obtained in step S1, and continue stirring until the solution becomes clear; S3. Add 1.92mg of graphene oxide (GO) to the solution obtained in step S2, and stir for 1h; S4. Transfer the solution obtained in step S3 to a reaction kettle, and react at 180℃ for 12 hours; S5. After naturally cooling the reaction kettle obtained in step S4, centrifuge to collect the product, wash it with deionized water and anhydrous ethanol for 3 times, and dry it at 80℃ overnight to obtain the product SnO2 / RGO (2.5wt%) composite thermosensitive material.

[0034] Example 2 Preparation of SnO2 / RGO (5wt%) composite thermistor The preparation of the SnO2 / RGO (5wt%) composite thermosensitive material is the same as in Example 1, except that the amount of graphene oxide (GO) added is changed, i.e., 3.96 mg of graphene oxide (GO) is added.

[0035] Example 3 Preparation of SnO2 / RGO (10wt%) composite thermistor The preparation of the SnO2 / RGO (10wt%) composite thermosensitive material is the same as in Example 1, except that the amount of graphene oxide (GO) added is changed, i.e., 8.4 mg of graphene oxide (GO) is added.

[0036] Example 4 Preparation of SnO2 / RGO (15wt%) composite thermistor The preparation of the SnO2 / RGO (15wt%) composite thermosensitive material is the same as in Example 1, except that the amount of graphene oxide (GO) added is changed, i.e., 13.08 mg of graphene oxide (GO) is added.

[0037] Example 5 Preparation of SnO2 / RGO (20wt%) composite thermistor The preparation of the SnO2 / RGO (20wt%) composite thermosensitive material is the same as in Example 1, except that the amount of graphene oxide (GO) added is changed, i.e., 18.6 mg of graphene oxide (GO) is added.

[0038] Applications of SnO2 / RGO composite thermistors Example 6 The manufacturing process of temperature sensor components is as follows: S1. Weigh 0.16g of polyvinylidene fluoride (PVDF) into 10mL of N-methyl-2-pyrrolidone (NMP), stir until dissolved, and obtain a PVDF / NMP solution; S2. Weigh 20 mg of SnO2 / RGO composite thermosensitive material into 0.5 mL of the PVDF / NMP solution obtained in step S1, and stir until uniformly mixed to obtain SnO2 / RGO composite thermosensitive material slurry; S3. Use a pipette to take 6µL of the SnO2 / RGO composite thermosensitive material slurry obtained in step S2, and drop it onto the selected sensor substrate. After drying, encapsulate it to obtain the temperature sensor element.

[0039] The sensitivity is calculated by defining it as TCR=[(R T-R0) / R0] / ∆T; where R T R0 represents the resistance of the thermistor at temperature T, and R0 represents the initial resistance of the thermistor at the reference temperature (10℃). The hysteresis is calculated by using the maximum difference between the heating and cooling curves and the full-scale output value y. FS The percentage of the ratio is expressed as: γ H =±1 / 2(∆H m / y FS )×100%, where ∆H m It refers to the maximum difference between the two curves: response time is expressed as the time required for the temperature sensor to change from contact with the target temperature to the point where its output signal reaches a stable value.

[0040] Characterization of SnO2 / RGO composite thermistor The SnO2 / RGO composite thermistors prepared in Examples 1-5 were characterized and their performance tested by XRD diffraction, scanning electron microscopy, and XPS. Specifically, a high-low temperature test chamber was used to control the temperature rise and fall within the range of 10℃-100℃ in 10℃ increments. An Agilent digital data acquisition system was used to collect the resistance changes of the SnO2 / RGO composite thermistors during the temperature change process, with sampling performed every 1 second. The temperature sensing performance of this composite material was then tested. Specific test results are as follows: Figures 1-8 As shown.

[0041] in conclusion according to Figures 1-8 The data analysis yielded the following conclusions: (1) Figure 1 The XRD patterns of the SnO2 / RGO composite thermistors prepared in Examples 1-5 are shown. The diffraction peaks of all samples prepared in Examples 1-5 correspond to the diffraction peaks of the (110), (101), (200), (211), (220), (112), (301) and (321) crystal planes of the standard diffraction pattern of tetragonal tin dioxide (JCPDS card No. 41-1445), indicating that the incorporation of RGO did not change the crystal form of SnO2.

[0042] (2) Figure 2 This is a SEM image of the SnO2 / RGO composite thermosensitive material prepared in Example 2. According to... Figure 2 The SEM images show that spherical SnO2 is dispersed on the two-dimensional sheet-like RGO surface.

[0043] (3) Figure 3XPS spectra of the SnO2 / RGO (5wt%) composite thermistor prepared in Example 2 are shown. In the XPS spectra, in the C1s fitting plot, CC bonds are present at 283.6 eV, CO bonds at 284.8 eV, and C=O bonds at 286.7 eV, with CC bonds being the dominant type, corresponding to the common RGO chemical bond composition in the literature. In the Sn3d fitting plot, two distinct peaks are located at 493.8 eV and 4855.4 eV, corresponding to the Sn3d 3 / 2 and Sn3d 5 / 2 peaks, respectively, with a spin energy separation value of 8.4 eV, consistent with the peaks of SnO2 powder in the literature; indicating that the main components of the SnO / RGO powder are RGO and SnO2. In the O1s fitting plot, the two fitting peaks correspond to the Sn-O bond at 529.5 eV and the CO-Sn bond at 530.4 eV, respectively. The obvious CO-Sn bond fitting peak indicates that there is a strong interfacial bond between SnO2 and RGO.

[0044] (3) Figure 4 The graph shows the sensitivity and linearity of the SnO2 / RGO (5wt%) composite thermistor prepared in Example 2 within the temperature measurement range of 10℃ to 100℃. According to the linear fitting results, the sensitivity of the SnO2 / RGO (5wt%) composite thermistor is -0.766% / ℃ and the linearity is 99.64%.

[0045] (4) Figure 5 The diagram shows the hysteresis of the SnO2 / RGO (5wt%) composite thermistor prepared in Example 2 during the heating and cooling process from 10℃ to 100℃. The SnO2 / RGO (5wt%) composite thermistor was calculated to have a small hysteresis value of 1.74%.

[0046] (5) Figure 6 The SnO2 / RGO (5wt%) composite thermistor prepared in Example 2 had a response time of 40s under rapid temperature changes from 25℃ to 70℃.

[0047] (6) Figure 7 The SnO2 / RGO (5wt%) composite thermistor material prepared in Example 2 was subjected to six consecutive heating and cooling tests within a temperature measurement range of 10~100℃. The results showed that the relative resistance of the temperature sensor exhibited good repeatability with temperature changes during the six-cycle test.

[0048] (7) Figure 8 The graph shows the changes in sensitivity and linearity of the SnO2 / RGO (5wt%) composite thermistor prepared in Example 2 over 30 days. The results show that the sensitivity and linearity of the temperature sensor did not fluctuate significantly during the 30-day test, indicating good stability.

[0049] In summary, the SnO2 / RGO composite thermosensitive material, its preparation method, and its application in this embodiment of the invention use stannous chloride dihydrate and oxalic acid as reactants, polyvinylpyrrolidone as a dispersant, and deionized water as a solvent. The SnO2 / RGO composite thermosensitive material is prepared by a one-step solvothermal method, and its preparation process is simple.

[0050] Furthermore, the SnO2 / RGO composite thermistor material prepared in the embodiments of the present invention was used to fabricate a temperature sensing element and its performance was tested. The SnO2 / RGO composite thermistor material exhibits a sensitivity of -0.766% / ℃, a linearity as high as 99.64%, and a hysteresis value of 1.74% within a temperature measurement range of 10~100℃. It also demonstrates good repeatability and stability, which is of significant practical importance for temperature monitoring of lithium-ion power batteries.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The preparation method according to claim 1, characterized in that, The reactants include stannous chloride and oxalic acid.

2. The preparation method according to claim 1, characterized in that, The reactants include stannous chloride and oxalic acid.

3. The preparation method according to claim 1 or 2, characterized in that, The dispersant is polyvinylpyrrolidone.

4. The preparation method according to claim 3, characterized in that, In the solvothermal reaction, the mass ratio of stannous chloride, oxalic acid, and polyvinylpyrrolidone is (0.116~58):(2.15~1075):(1.1~550).

5. The preparation method according to any one of claims 1 to 4, characterized in that, The reaction temperature of the solvothermal reaction is 180°C; And / or, the reaction time is 12 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In the SnO2 / RGO composite thermistor, the RGO content is 2.5~20wt%.

7. A SnO2 / RGO composite thermosensitive material obtained by the preparation method according to any one of claims 1 to 6.

8. The application of the SnO2 / RGO composite thermistor material as described in claim 7 in the preparation of temperature sensor elements.

9. The application according to claim 8, characterized in that, The method for fabricating the temperature sensor element includes: SnO2 / RGO composite thermosensitive material was mixed with PVDF / NMP solution to obtain SnO2 / RGO composite thermosensitive material slurry; The SnO2 / RGO composite thermosensitive material slurry was drop-coated onto the sensor substrate, and then dried and encapsulated sequentially to obtain a temperature sensor element.

10. The application according to claim 9, characterized in that, The concentration of the PVDF / NMP solution is 0.016 g / mL to 0.02 g / mL.

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