Ion-doped thermoelectric thin film, method for preparing the same, and application thereof in temperature sensor

Abstract

The application provides an ion-doped thermoelectric thin film, a preparation method thereof and application in a temperature sensor, and belongs to the technical field of temperature sensors. N-methylpyrrolidone is mixed with polyvinylidene fluoride-hexafluoropropylene copolymer to obtain solution A; solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide and lithium tetrafluoroborate are mixed to obtain solution B; solution B is vacuum dried on a mold to obtain an ion-doped thermoelectric thin film; through lithium salt doping, amorphous state transformation of an organic polymer is caused, the stability of sensing is improved, the response time of sensing is shortened, and the performance of the sensor is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sensor devices, and particularly relates to an ion-doped thermoelectric film, a preparation method thereof and application thereof in temperature sensors. BACKGROUND

[0002] In the industrial field and daily life field, it is necessary to accurately detect heat flow and temperature. A thermoelectric device based on the Seebeck effect generates a thermoelectric voltage V through carrier diffusion under a certain temperature difference Δ T Δ Δ V = V hot -Vc old , which provides a feasible and direct solution for directly converting heat into electricity. It has temperature sensing capability.

[0003] The Seebeck coefficient (or thermoelectric power, = -ΔV / □T) of electronic high-performance thermoelectric materials ranges from tens to hundreds of microvolts per Kelvin. The microvolt-level Seebeck coefficient of electronic thermoelectric materials greatly limits their thermal sensitivity. In a thermoelectric temperature sensor or other thermoelectric stack configuration, a large number of units must be integrated to amplify the signal output, which usually leads to complex manufacturing and high cost. At the same time, the high Seebeck coefficient of insulators leads to low conductivity, resulting in large measurement noise. It is a challenge to significantly improve the Seebeck coefficient without sacrificing other important thermoelectric properties (such as conductivity).

[0004] Therefore, ion-type thermoelectric materials emerged as the times require. In the reports in the past five years, ion thermoelectric materials have a Seebeck coefficient (or thermoelectric power) of millivolt level. Compared with electronic thermoelectric materials, the greatly enhanced thermoelectric power and reasonable ionic conductivity can achieve more sensitive temperature monitoring, especially for small temperature difference occasions, such as human body temperature monitoring and battery temperature measurement. Unlike traditional electronic thermoelectric materials which are rigid bulk metals or semiconductors, ion-type thermoelectric materials have the advantages of flexibility and easy manufacturing. Ion thermoelectric materials are good candidates for the medical and health care field and wearable thermal sensors.

[0005] Therefore, there is an urgent need for a thin film material for temperature sensors with stable thermoelectric voltage, high corresponding sensitivity and resistance to environmental interference. SUMMARY

[0006] Therefore, the application aims to provide an ion-doped thermoelectric film, a preparation method thereof and application thereof in temperature sensors. The sensor prepared from the film has a millivolt-level thermoelectric voltage response, the ion thermoelectric film material has stable thermoelectric voltage, and has recovery ability after environmental interference in a fixed temperature difference situation, so that stable and timely temperature monitoring can be achieved.

[0007] In order to achieve the above-mentioned purpose, the application provides the following technical solutions:​

[0008] In a first aspect, the present application provides a preparation method of ion-doped thermoelectric thin film, comprising the following steps:

[0009] 1) mixing and stirring N-methylpyrrolidone and polyvinylidene fluoride-hexafluoropropylene copolymer to obtain solution A;

[0010] 2) mixing and stirring solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate to obtain solution B;

[0011] 3) vacuum drying solution B on a mold to obtain ion-doped thermoelectric thin film.

[0012] Preferably, the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride-hexafluoropropylene copolymer in step 1) is 5-47:1-3.

[0013] Preferably, the temperature for mixing and stirring in step 1) is 60-80℃, and the time is 8-12h.

[0014] Preferably, the mass ratio of solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate in step 2) is (20-80):(5-80):(5-80):(5-50).

[0015] Preferably, the temperature for mixing and stirring in step 2) is 20-30℃, and the time is 6-12h.

[0016] Preferably, the temperature for vacuum drying in step 3) is 50-80℃, and the time is 8-16h.

[0017] In a second aspect, the present application provides an ion-doped thermoelectric thin film prepared by the above preparation method.

[0018] In a third aspect, the present application provides an application of the above ion-doped thermoelectric thin film in a temperature sensor.

[0019] In a fourth aspect, the present application provides a temperature sensor comprising the above ion-doped thermoelectric thin film, a fixed electrode, and a temperature measuring electrode; the ion-doped thermoelectric thin film is an intermediate layer, and the fixed electrode and the temperature measuring electrode form a sandwich structure on both sides of the ion-doped thermoelectric thin film.

[0020] Preferably, the electrode material is copper, silver, or graphite material.

[0021] The present application at least has the following beneficial technical effects:

[0022] (1) The ion-doped thermoelectric thin film obtained by the present application has millivolt-level thermoelectric voltage;

[0023] (2) The ion-doped thermoelectric thin film obtained by the present application has stable and smooth voltage curve in response to temperature difference, and does not have phenomena such as inclined rise or decline and fluctuation.

[0024] (3) The ion-doped thermoelectric thin film material obtained by the present application is very flexible and light, and does not occupy too much space when collecting temperature difference.

[0025] (4) The ion-doped thermoelectric thin film material obtained by the present application has certain anti-freezing ability and can still work at 0-30 degrees Celsius. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 SEM image of the thermoelectric thin film prepared in Example 1.

[0027] Figure 2 SEM image of the thermoelectric thin film prepared in Comparative Example 1.

[0028] Figure 3 Temperature-dependent thermoelectric voltage curve of the thermoelectric thin film prepared in Example 1.

[0029] Figure 4 Temperature-dependent thermoelectric voltage curve of the thermoelectric thin film prepared in Comparative Example 1.

[0030] Figure 5 Conceptual diagram of sensor array arrangement.

[0031] Figure 6 Temperature distribution diagram of sensor array. DETAILED DESCRIPTION

[0032] The technical solutions of the present application are further described below by means of drawings and examples.

[0033] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.

[0034] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application, and any reference signs in the claims should not be regarded as limiting the claims involved.

[0035] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment exhibits every characteristic or exhibits the described implementation to the full extent. The specification is therefore to be interpreted as a whole, and the embodiments in their entirety, to be read in view of, and in light of, the totality of the specification and claims, and the various embodiments thereof can be combined with each other, and / or combined with the subject matter of the disclosure, in any manner permitted by the disclosure and the principles and practice of patent law. Any such combination is to be considered within the scope of the present disclosure.

[0036] It should also be understood that the above description is only specific embodiments of the present application, and the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical scope disclosed by the present application, and such replacements or changes should be covered within the protection scope of the present application.

[0037] Embodiment 1

[0038] The present embodiment provides an ion-doped thermoelectric thin film, and the preparation method is as follows:

[0039] 1) N-methylpyrrolidone and polyvinylidene fluoride-hexafluoropropylene copolymer are mixed in a mass ratio of 9:1, stirred at 60°C for 12h, and a solution A is prepared.

[0040] 2) Solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate are mixed and stirred to obtain solution B, which is mixed in a mass ratio of 27.3:31.8:31.8:9.1, stirred at 25°C for 8h, and solution B is prepared.

[0041] 3) Solution B is dropped onto a mold with a dropper, the mold filled with solution B is moved to a vacuum drying oven, vacuum dried at 60°C for 12h, and after drying is completed, the prepared thin film is taken out of the mold, cut into a certain shape, and a thermoelectric thin film is obtained.

[0042] Embodiment 2

[0043] The present embodiment provides an ion-doped thermoelectric thin film, and the preparation method is as follows:

[0044] 1) N-methylpyrrolidone and polyvinylidene fluoride-hexafluoropropylene copolymer are mixed in a mass ratio of 5:1, stirred at 80°C for 8h, and a solution A is prepared.

[0045] 2) Solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate are mixed and stirred to obtain solution B, which is mixed in a mass ratio of 20:5:5:5, stirred at 30°C for 12h, and solution B is prepared.

[0046] 3) The solution B is dropped onto the mold with a dropper, and the mold filled with the solution B is moved to a vacuum drying oven, and vacuum dried at 80°C for 16h. After drying is completed, the prepared film is removed from the mold, cut into a certain shape, and a thermoelectric film is obtained.

[0047] Example 3

[0048] The present example provides an ion-doped thermoelectric film, and the preparation method is as follows:

[0049] 1) N-methylpyrrolidone and polyvinylidene-hexafluoropropylene copolymer are mixed in a mass ratio of 47:3, stirred at 70°C for 10h, and solution A is prepared.

[0050] 2) Solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate are mixed and stirred to obtain solution B, which is mixed in a mass ratio of 80:80:80:50, stirred at 20°C for 6h, and solution B is prepared.

[0051] 3) The solution B is dropped onto the mold with a dropper, and the mold filled with the solution B is moved to a vacuum drying oven, and vacuum dried at 70°C for 8h. After drying is completed, the prepared film is removed from the mold, cut into a certain shape, and a thermoelectric film is obtained.

[0052] Comparative Example 1

[0053] The preparation method of the present comparative example is the same as that of Example 1, except that lithium tetrafluoroborate is not added in step 2).

[0054] Test Example 1

[0055] The thermoelectric films prepared in Example 1 and Comparative Example 1 are observed, and the scanning electron microscope images of the thermoelectric films of Example 1 and Comparative Example 1 are shown in Figure 1 , Figure 2 .

[0056] Test Example 2

[0057] The thermoelectric films prepared in Example 1 and Comparative Example 1 are tested for thermoelectric voltage, and it can be seen from Figures 3-4 that the thermoelectric voltage stability of Example 1 is significantly improved compared with Comparative Example 1.

[0058] Test Example 3

[0059] The sensor is successfully prepared by placing it on a designed integrated circuit (16 units are integrated on the integrated circuit, and each unit is independent of each other), and packaging the sensor by a vacuum sealing machine, and the sensor is shown in Figure 5 , Figure 6 .

[0060] The above descriptions are only the preferred embodiments of the present application, and are not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an ion-doped thermoelectric thin film, characterized in that: The following steps are involved: 1) mixing N-methylpyrrolidone and polyvinylidene fluoride-hexafluoropropylene copolymer and stirring to obtain solution A; 2) mixing solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate, and stirring to obtain solution B; 3) Placing solution B on a mold and vacuum drying it to obtain an ion-doped thermoelectric thin film.

2. The preparation method according to claim 1, characterized in that In the step 1), the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride-hexafluoropropylene copolymer is 5-47:1-3.

3. The preparation method according to claim 1, characterized in that The mixing and stirring in step 1) is performed at a temperature of 60-80° C. and for 8-12 hours.

4. The preparation method according to claim 1, characterized in that In the step 2), the mass ratio of solution A, 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate is 20-80:5-80:5-80:5-50.

5. The preparation method according to claim 1, characterized in that The mixing and stirring temperature in step 2) is 20-30° C. and the stirring time is 6-12 h.

6. The preparation method according to claim 1, characterized in that The vacuum drying temperature in step 3) is 50-80° C. and the drying time is 8-16 hours.

7. The ion-doped thermoelectric thin film prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the ion-doped thermoelectric film according to claim 7 in a temperature sensor.

9. A temperature sensor, characterized in that: It comprises the ion-doped thermoelectric film, fixed electrode and temperature measuring electrode as described in claim 7; the ion-doped thermoelectric film is the middle layer, and the fixed electrode and the temperature measuring electrode form a sandwich structure on both sides of the ion-doped thermoelectric film.

10. The temperature sensor according to claim 9, characterized in that The electrode materials are copper, silver and graphite.

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