A flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite and its preparation method

Abstract

The present invention relates to a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite and a preparation method thereof. The method of the present invention comprises the following steps: 1. preparing a double perovskite solution with excellent performance by a convenient hydrothermal method; 2. compounding the perovskite crystal with high-performance fiber to prepare a flexible piezoelectric fiber; 3. the flexible piezoelectric fiber is combined with the support vector machine algorithm in Matlab to detect and identify the piezoelectric signals generated by different human body movements. The method is achieved by heating and stirring the reaction under low temperature and standard atmospheric pressure environment. The preparation method is simple, convenient and economical. The prepared double perovskite crystal has a regular octahedral structure and piezoelectric properties. It can be compounded with high-performance fiber to prepare a flexible piezoelectric fiber. The piezoelectric signal generated by the flexible piezoelectric fiber prepared by this method can realize human body movement recognition and can be used as a flexible intelligent wearable device.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and in particular to a cesium sodium bismuth halide double perovskite for flexible piezoelectric fibers and a preparation method thereof. Background Art

[0002] Lead-based halide perovskites have a range of excellent optoelectronic properties and have therefore been widely studied in various optoelectronic device fields. However, the environmental toxicity and air stability of lead elements make it difficult to obtain large-scale commercial applications. + M 3+ X6 is one of the options to replace lead-based halide perovskites. On the one hand, M + With M 3+ It is easy to find environmentally friendly elements to replace lead. Furthermore, by doping with other elements, the emission wavelength can be tuned to achieve full-band visible light emission. Current methods for preparing double perovskite structures mostly use high-temperature solid-phase methods and reactor hydrothermal methods, which are costly and unfavorable for large-scale industrial production of double perovskite materials.

[0003] At the same time, with the advancement of technology, smart wearable devices are increasingly appearing in people's lives. These devices include smart watches, smart clothing, and smart accessories. Perovskite, as an optoelectronic semiconductor material with excellent performance, has broad application potential in the field of smart wearable devices. Summary of the Invention

[0004] In response to the above problems, the present invention has found the optimal reaction conditions for preparing lead-free double perovskite Cs2NaBiCl6 by regulating the synthesis time, synthesis temperature and the feed ratio of raw materials. At the same time, different elements are doped to regulate its luminescence band to achieve multi-band luminescence. The prepared lead-free double perovskite has an octahedral structure and has piezoelectric properties. In addition, the present invention composites the lead-free double perovskite with high-performance fibers to prepare flexible piezoelectric fibers. The piezoelectric signal generated by the flexible piezoelectric fiber prepared by the present invention can be used to realize human motion recognition through Matlab tools, and has broad application prospects in the field of flexible intelligent wearable devices.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite, comprising the following steps:

[0007] Step 1: Add hydrochloric acid and alcohol to cesium chloride, and stir thoroughly at 60°C-100°C until cesium chloride is completely dissolved to obtain a cesium chloride solution;

[0008] Step 2: adding hydrochloric acid and alcohol to sodium chloride, bismuth chloride, and manganese chloride, and stirring thoroughly at 60° C. to 100° C. until the solids are completely dissolved to obtain a mixed solution;

[0009] Step 3, preheating the cesium chloride solution in step 1 and adding it to the mixed solution in step 2, reacting under conditions of heating and sufficient stirring, cooling in a water bath and centrifuging after the reaction is completed to obtain a lead-free double perovskite Cs2NaBiCl6 solution;

[0010] Step 4: Prepare ACFs / PPS composite fiber paper using aramid chopped fibers and polyphenylene sulfide, and soak the ACFs / PPS composite fiber paper in Cs2NaBiCl6 solution. Dry the treated composite fiber paper and then hot-press it to obtain a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite.

[0011] Furthermore, in step 1, the amounts of cesium chloride, hydrochloric acid and alcohol are 0.1-0.5 g, 2-8 mL and 5-15 mL, respectively.

[0012] Furthermore, in step 2, the amounts of sodium chloride, bismuth chloride, manganese chloride, hydrochloric acid and alcohol are 0.05-0.2 g, 0.1-0.5 g, 0.005-0.02 g, 2-8 mL and 5-15 mL, respectively.

[0013] Furthermore, the amount of cesium chloride solution added in step 3 is 5-10 mL.

[0014] Furthermore, the reaction time in step 3 is 0-60 min, the solvent required for the centrifugal purification process is n-hexane, the centrifugal speed is 6000 rpm, the centrifugal time is 5 min, and the number of centrifugation is two times.

[0015] Furthermore, the method for preparing ACFs / PPS composite fiber paper using aramid chopped fibers and polyphenylene sulfide in step 4 includes the following steps:

[0016] Step 4.1, using acetone to clean the aramid chopped fibers and the PPS nonwoven fabric to remove impurities;

[0017] Step 4.2, processing the PPS nonwoven fabric into PPS microfiber pulp through a beating machine;

[0018] Step 4.3, stirring anionic polyacrylamide, sodium dodecylbenzene sulfonate and polyethylene oxide in deionized water to obtain a dispersion;

[0019] Step 4.4, adding PPS microfiber pulp and aramid short-cut fibers into the dispersion prepared in the previous step at a mass ratio of 1-9:1-9, and dispersing the mixture using a fiber disintegrator;

[0020] Step 4.5: Using a paper machine to prepare the mixed fiber suspension by a wet papermaking method to obtain ACFs / PPS composite fiber paper.

[0021] Furthermore, the hot pressing temperature in step 4 is 80-200°C.

[0022] The flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite is prepared by the above method.

[0023] Application of flexible piezoelectric fiber composites based on cesium sodium bismuth halide double perovskite in flexible smart wearable devices.

[0024] The specific application method is to load conductive materials on both sides of the flexible piezoelectric fiber composite material, and lead the conductive materials out in opposite directions to output piezoelectric signals.

[0025] After adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0026] The preparation method of cesium sodium bismuth halide double perovskite for flexible piezoelectric fibers provided by the present invention provides a convenient synthesis idea for the preparation of Cs2NaBiX6 (X=Cl, Br, I) lead-free double perovskite, which is beneficial to the large-scale industrial production of lead-free double perovskite. The experiment adopts a convenient hydrothermal method for preparation. The temperature is at a low level during the synthesis process, and the process is carried out under standard atmospheric pressure. The operation is convenient and the synthesis cost is low. At the same time, the prepared cesium sodium bismuth halide double perovskite has good optical and piezoelectric properties, and a regular morphology, which is conducive to compounding with high-performance fibers to prepare flexible piezoelectric fibers. The prepared flexible piezoelectric fiber has good piezoelectric properties, and the piezoelectric response time and recovery time are at the millisecond level, which can be applied to smart wearable and other fields.

[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 XRD patterns of Cs2NaBiCl6 doped with different elements;

[0029] Figure 2 This is the fluorescence spectrum of Mn-doped Cs2NaBiCl6;

[0030] Figure 3 The scanning electron microscope image and elemental energy spectrum of Mn-doped Cs2NaBiCl6;

[0031] Figure 4 The piezoelectric signal diagram of the flexible piezoelectric fiber made by combining Mn-doped Cs2NaBiCl6 and ACFs / PPS;

[0032] Figure 5 This is a comparison chart of the prediction results of different human body movements using flexible piezoelectric fibers combined with the support vector machine algorithm in Matlab tools. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0035] Example 1

[0036] A cesium sodium bismuth halide double perovskite for flexible piezoelectric fiber and a preparation method thereof, comprising the following steps:

[0037] Step 1: Add 2-8 mL of hydrochloric acid and 5-15 mL of alcohol to 0.1-0.5 g of cesium chloride and stir thoroughly at 60-100 ° C until the cesium chloride is completely dissolved;

[0038] Step 2: Add 2-8 mL of hydrochloric acid and 5-15 mL of alcohol to 0.05-0.2 g of sodium chloride and 0.1-0.5 g of bismuth chloride, and stir thoroughly at 60°C-100°C until the solid is completely dissolved to obtain a mixed solution;

[0039] Step 3: Preheat 5-10 mL of the cesium chloride solution in step 1 and add it to the mixed solution in step 2. React under conditions of heating and sufficient stirring. After the reaction is completed, cool in a water bath and centrifuge to obtain a lead-free double perovskite Cs2NaBiCl6 solution.

[0040] Step 4: Use acetone to clean aramid chopped fibers (ACFs) and polyphenylene sulfide (PPS) to remove impurities. Subsequently, the PPS nonwoven fabric is processed into PPS microfiber pulp by a beater. Next, anionic polyacrylamide (APAM), sodium dodecylbenzene sulfonate (SDS) and polyethylene oxide (PEO) are stirred in deionized water in a certain proportion to obtain a dispersion. Then, PPS microfiber pulp and ACFs are added to this dispersion in a mass ratio of 1:9 to 9:1 and dispersed using a fiber disintegrator. Finally, the mixed fiber suspension is directly used for wet papermaking on a papermaking machine to obtain ACFs / PPS composite fiber paper.

[0041] Step 5. Use the Cs2NaBiCl6 solution obtained in step 3 to post-treat the aramid chopped fiber / polyphenylene sulfide (ACFs / PPS) composite fiber paper obtained in step 4. Use the Cs2NaBiCl6 solution to soak the ACFs / PPS composite fiber paper, dry the entire post-treated composite fiber paper, and then hot-press the entire fiber paper at 80-200°C to obtain flexible piezoelectric fibers.

[0042] Step 6: Load the conductive copper foil on both sides of the flexible piezoelectric fiber in step 5, and lead the conductive copper foil in opposite directions so that the piezoelectric signal can be collected by the subsequent oscilloscope.

[0043] Test characterization:

[0044] Take the lead-free double perovskite Cs2NaBiCl6 product obtained in step 3, test XRD, SEM, and determine its substance, such as Figure 1 As shown, the XRD pattern of Cs2NaBiCl6 is consistent with the standard card PDF#77-1831, and the target product is consistent with the preset product.

[0045] Example 2

[0046] A cesium sodium bismuth halide double perovskite for flexible piezoelectric fiber and a preparation method thereof, comprising the following steps:

[0047] Step 1: Add 2-8 mL of hydrochloric acid and 5-15 mL of alcohol to 0.1-0.5 g of cesium chloride and stir thoroughly at 60-100 ° C until the cesium chloride is completely dissolved;

[0048] Step 2: Add 2-8 mL of hydrochloric acid and 5-15 mL of alcohol to 0.05-0.2 g of sodium chloride, 0.1-0.5 g of bismuth chloride, and 0.005-0.02 g of manganese chloride, and stir thoroughly at 60°C-100°C until the solids are completely dissolved to obtain a mixed solution;

[0049] Step 3: Preheat 5-10 mL of the cesium chloride solution in step 1 and add it to the mixed solution in step 2. React under conditions of heating and sufficient stirring. After the reaction is completed, cool in a water bath and centrifuge to obtain a lead-free double perovskite Cs2NaBiCl6 solution.

[0050] Step 4: Use acetone to clean aramid chopped fibers (ACFs) and polyphenylene sulfide (PPS) to remove impurities. Subsequently, the PPS nonwoven fabric is processed into PPS microfiber pulp by a beater. Next, anionic polyacrylamide (APAM), sodium dodecylbenzene sulfonate (SDS) and polyethylene oxide (PEO) are stirred in deionized water in a certain proportion to obtain a dispersion. Then, PPS microfiber pulp and ACFs are added to this dispersion in a mass ratio of 1:9 to 9:1 and dispersed using a fiber disintegrator. Finally, the mixed fiber suspension is directly used for wet papermaking on a papermaking machine to obtain ACFs / PPS composite fiber paper.

[0051] Step 5. Use the Cs2NaBiCl6 solution obtained in step 3 to post-treat the aramid chopped fiber / polyphenylene sulfide (ACFs / PPS) composite fiber paper obtained in step 4. Use the Cs2NaBiCl6 solution to soak the ACFs / PPS composite fiber paper, dry the entire post-treated composite fiber paper, and then hot-press the entire fiber paper at 80-200°C to obtain flexible piezoelectric fibers.

[0052] Step 6: Load the conductive silver foil on both sides of the flexible piezoelectric fiber in step 5, and lead the conductive silver foil in opposite directions to obtain a flexible piezoelectric fiber device so that the piezoelectric signal can be collected by the subsequent oscilloscope.

[0053] Test characterization:

[0054] Take step 3 to obtain the lead-free double perovskite Cs2NaBiCl6 product doped with Mn element, test XRD, SEM to determine its substance; test PL to determine its fluorescence properties, such as Figure 2 As shown, the obtained Mn-doped Cs2NaBiCl6 product has fluorescent properties.

[0055] Example 3

[0056] A cesium sodium bismuth halide double perovskite for flexible piezoelectric fiber and a preparation method thereof, comprising the following steps:

[0057] Step 1: Add 2-8 mL of hydrochloric acid and 5-15 mL of alcohol to 0.1-0.5 g of cesium chloride and stir thoroughly at 60-100 ° C until the cesium chloride is completely dissolved;

[0058] Step 2: Add 2-8 mL of hydrochloric acid and 5-15 mL of alcohol to 0.05-0.2 g of sodium chloride, 0.1-0.5 g of bismuth chloride, and 0.005-0.02 g of manganese chloride, and stir thoroughly at 60°C-100°C until the solids are completely dissolved to obtain a mixed solution;

[0059] Step 3: Preheat 5-10 mL of the cesium chloride solution in step 1 and add it to the mixed solution in step 2. React under conditions of heating and sufficient stirring. After the reaction is completed, cool in a water bath and centrifuge to obtain a lead-free double perovskite Cs2NaBiCl6 solution.

[0060] Step 4: Use acetone to clean aramid chopped fibers (ACFs) and polyphenylene sulfide (PPS) to remove impurities. Subsequently, the PPS nonwoven fabric is processed into PPS microfiber pulp by a beater. Next, anionic polyacrylamide (APAM), sodium dodecylbenzene sulfonate (SDS) and polyethylene oxide (PEO) are stirred in deionized water in a certain proportion to obtain a dispersion. Then, PPS microfiber pulp and ACFs are added to this dispersion in a ratio of 1:9 to 9:1 and dispersed using a fiber disintegrator. Finally, the mixed fiber suspension is directly used for wet papermaking on a papermaking machine to obtain ACFs / PPS composite fiber paper.

[0061] Step 5. Use the Cs2NaBiCl6 solution obtained in step 3 to post-treat the aramid chopped fiber / polyphenylene sulfide (ACFs / PPS) composite fiber paper obtained in step 4. Use the Cs2NaBiCl6 solution to soak the ACFs / PPS composite fiber paper, dry the entire post-treated composite fiber paper, and then hot-press the entire fiber paper at 80-200°C to obtain flexible piezoelectric fibers.

[0062] Step 6: Load the front and back sides of the flexible piezoelectric fiber prepared in step 5 with conductive copper foil, and lead the conductive copper foil out in opposite directions to obtain a flexible piezoelectric fiber device so that the piezoelectric signal can be collected by the subsequent oscilloscope.

[0063] Test characterization:

[0064] The lead-free double perovskite Cs2NaBiCl6 product obtained in step 3 was tested by XRD and SEM to identify its substance and by PL to determine its fluorescence properties. The flexible piezoelectric fiber device obtained in step 6 was tested for piezoelectric signal to determine its piezoelectric performance.

[0065] according to Figure 3 As shown in the middle (ag) figure, the reaction temperature is 80-100 ° C, the reaction time is 30-60 min, and the obtained Mn-doped lead-free double perovskite Cs2NaBiCl6 has an average size distribution of 1-5 μm, an octahedral shape, and the element distribution is consistent with the preset preparation product; according to Figure 4 As shown in the figure, the response and recovery time of the flexible piezoelectric fiber are measured to be 30-50ms, which shows good piezoelectric properties. Figure 5As shown, the flexible piezoelectric fiber is combined with the support vector machine algorithm in the Matlab tool to realize the classification, recognition and prediction of different human body movements with an accuracy rate of up to 99%.

[0066] The foregoing is an example of the best mode of carrying out the present invention. Any portion not described in detail herein is common knowledge within the skill of one of ordinary skill in the art. The scope of protection of the present invention is determined by the claims. Any equivalent transformation based on the technical teachings of the present invention is also within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite, characterized in that: The following steps are involved: Step 1: Add hydrochloric acid and alcohol to cesium chloride, and stir thoroughly at 60°C-100°C until cesium chloride is completely dissolved to obtain a cesium chloride solution; Step 2: adding hydrochloric acid and alcohol to sodium chloride, bismuth chloride, and manganese chloride, and stirring thoroughly at 60° C. to 100° C. until the solids are completely dissolved to obtain a mixed solution; Step 3, preheating the cesium chloride solution in step 1 and adding it to the mixed solution in step 2, reacting under conditions of heating and sufficient stirring, cooling in a water bath and centrifuging after the reaction is completed to obtain a lead-free double perovskite Cs2NaBiCl6 solution; Step 4: Prepare ACFs / PPS composite fiber paper using aramid chopped fibers and polyphenylene sulfide, and soak the ACFs / PPS composite fiber paper in Cs2NaBiCl6 solution. Dry the treated composite fiber paper and then hot-press it to obtain a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite.

2. The method for preparing a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 1, characterized in that: In the step 1, the amounts of cesium chloride, hydrochloric acid and alcohol used are 0.1-0.5 g, 2-8 mL and 5-15 mL respectively.

3. The method for preparing the flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 1, characterized in that: In the step 2, the amounts of sodium chloride, bismuth chloride, manganese chloride, hydrochloric acid and alcohol are 0.05-0.2 g, 0.1-0.5 g, 0.005-0.02 g, 2-8 mL and 5-15 mL, respectively.

4. The method for preparing a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 1, characterized in that: The amount of cesium chloride solution added in step 3 is 5-10 mL.

5. The method for preparing the flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 1, characterized in that: The reaction time in step 3 is 0-60 min, the solvent required for the centrifugal purification process is n-hexane, the centrifugal speed is 6000 rpm, the centrifugal time is 5 min, and the number of centrifugations is two.

6. The method for preparing the flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 1, characterized in that: The method for preparing ACFs / PPS composite fiber paper using aramid chopped fibers and polyphenylene sulfide in step 4 comprises the following steps: Step 4.1, using acetone to clean the aramid chopped fibers and the PPS nonwoven fabric to remove impurities; Step 4.2, processing the PPS nonwoven fabric into PPS microfiber pulp through a beating machine; Step 4.3, stirring anionic polyacrylamide, sodium dodecylbenzene sulfonate and polyethylene oxide in deionized water to obtain a dispersion; Step 4.4, adding PPS microfiber pulp and aramid short-cut fibers into the dispersion prepared in the previous step at a mass ratio of 1-9:1-9, and dispersing the mixture using a fiber disintegrator; Step 4.5: Using a paper machine to prepare the mixed fiber suspension by a wet papermaking method to obtain ACFs / PPS composite fiber paper.

7. The method for preparing a flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 1, characterized in that: The hot pressing temperature in step 4 is 80-200°C.

8. A flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. Use of the flexible piezoelectric fiber composite material based on cesium sodium bismuth halide double perovskite according to claim 8 in flexible intelligent wearable devices.

10. The use according to claim 9, characterized in that The specific application method is to load conductive materials on both sides of the flexible piezoelectric fiber composite material, and lead the conductive materials out in opposite directions to output piezoelectric signals.

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