Room temperature solid-state polymer electrolyte and preparation method and application thereof

Abstract

The application discloses a normal-temperature solid-state polymer electrolyte and a preparation method and application thereof, and relates to the technical field of electrolyte materials.The electrolyte comprises the following steps: mixing and stirring polyvinylidene fluoride powder and a N,N dimethylformamide solution at room temperature to form a solution, and then drying the solution to obtain a PVDF base film; performing chemical modification on the PVDF base film, first performing alkalization treatment on the PVDF base film to make the PVDF base film generate carbon-carbon double bonds, then grafting polystyrene onto the PVDF, and finally putting the PVDF into concentrated sulfuric acid to perform sulfonation, so as to obtain a polyvinylidene fluoride grafted polystyrene sulfonic acid film, namely the normal-temperature solid-state polymer electrolyte.The preparation method of the normal-temperature solid-state polymer-based electrochemical hydrogen sensor comprises the following steps: cutting the normal-temperature solid-state polymer electrolyte, and covering the normal-temperature solid-state polymer electrolyte above a Pt / C working electrode, so as to obtain the normal-temperature solid-state polymer-based electrochemical hydrogen sensor.The normal-temperature solid-state polymer-based electrochemical hydrogen sensor designed by the application has the advantages of good selectivity, high sensitivity, low cost and room-temperature workability.

Description

Technical Field

[0001] This invention relates to the field of electrochemical gas sensor technology, specifically to room-temperature solid polymer electrolytes, their preparation methods, and applications. Background Technology

[0002] In recent years, food consumption patterns have gradually changed people's eating habits and lifestyles, with the most significant trend being the rapid growth of food delivery consumption. Especially in China, the food delivery industry already accounts for 60% of the global market revenue. Statistics show that as of 2020, China's food delivery industry had generated 17 billion orders and had 50 million consumers. However, food delivery has certain adverse effects on human health, such as easily leading to obesity, high cholesterol, and irritable bowel syndrome (IBS). IBS is a digestive disorder with an extremely high prevalence, seriously affecting people's quality of life. Research shows that the exhaled breath of people with IBS contains more than 20 ppm of hydrogen. Therefore, using gas sensors to detect hydrogen in exhaled breath can enable the monitoring of human health status, which is becoming an increasingly attractive solution.

[0003] Electrochemical gas sensors are widely used in industry due to their high sensitivity and good selectivity. Currently, in hydrogen detection, electrochemical gas sensors primarily employ noble metal working electrodes (such as Pt) and perfluorosulfonic acid ion-exchange membrane electrolytes (such as Nafion membranes). However, the demanding operating conditions and high manufacturing cost of Nafion membranes prevent electrochemical gas sensors based on Nafion membranes as solid-state electrolytes from being used in everyday life. Therefore, a suitable and inexpensive alternative electrolyte is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a room-temperature solid polymer electrolyte, its preparation method and application, which has good applicability and low price.

[0005] In one aspect of the present invention, a method for preparing a room-temperature solid polymer electrolyte is provided. According to an embodiment of the present invention, the method includes the following steps:

[0006] Step 1: Mix polyvinylidene fluoride powder with N,N-dimethylformamide solution at room temperature to form a homogeneous solution, and then dry to obtain PVDF base film;

[0007] Step 2: Chemically modify the PVDF base membrane. First, alkalize the PVDF base membrane to generate carbon-carbon double bonds. Then, graft polystyrene onto the PVDF. Finally, sulfonate it with concentrated sulfuric acid to obtain a polyvinylidene fluoride-grafted polystyrene sulfonic acid membrane, which is the room temperature solid polymer electrolyte.

[0008] In addition, the method for preparing room-temperature solid polymer electrolyte according to the above embodiments of the present invention may also have the following additional technical features:

[0009] In some embodiments of the present invention, in step 1, the mass ratio of polyvinylidene fluoride to N,N-dimethylformamide is 15:85, the drying temperature is 60-70°C, the drying time is 1-2 hours, and the film thickness is 0.08-0.13 mm.

[0010] In some embodiments of the present invention, in step 2, the reagent used for alkalization is sodium hydroxide-ethanol solution, the alkalization temperature is 70°C, and the alkalization time is 70 min.

[0011] In some embodiments of the present invention, in step 2, the grafting step is as follows: the PVDF base film after alkalization is washed and placed in a mixture of benzoyl peroxide, tetrahydrofuran and styrene, and the grafting reaction is carried out in a water bath at 70°C for 12-16 hours to obtain a polyvinylidene fluoride-grafted polystyrene film, which is then placed in dichloromethane for swelling for 1-2 hours.

[0012] In some embodiments of the present invention, in step 2, the sulfonation temperature is 70-80°C and the sulfonation time is 8-12 hours.

[0013] In another aspect of the present invention, the present invention provides a room-temperature solid polymer electrolyte prepared according to the preparation method of the room-temperature solid polymer electrolyte described above.

[0014] In another aspect of the present invention, a method for preparing a room-temperature solid polymer-based electrochemical hydrogen sensor is proposed. In an embodiment of the present invention, the method includes the following steps: using Pt / C as the working electrode and reference electrode, Pt as the counter electrode, and the room-temperature solid polymer electrolyte as the electrolyte, cutting the room-temperature solid polymer electrolyte, and uniformly covering the Pt / C working electrode with the room-temperature solid polymer electrolyte using an extrusion method to obtain the room-temperature solid polymer-based electrochemical hydrogen sensor.

[0015] In addition, the method for preparing the room-temperature solid-state polymer-based electrochemical hydrogen sensor according to the above embodiments of the present invention may also have the following additional technical features:

[0016] In some embodiments of the present invention, the Pt / C working electrode is prepared as follows: Pt / C, deionized water, isopropanol and Nafion solution are mixed into a uniform slurry, which is then applied to the working electrode and reference electrode of the substrate with a glass pen and dried for later use.

[0017] In some embodiments of the present invention, the volume ratio of water, isopropanol, and Nafion solution is 2:3:4, the Pt / C content is 1.33 g / mL, the coating thickness is 0.05-0.1 mm, the drying temperature is 60-80°C, and the drying time is 0.5-1 h.

[0018] In another aspect of the present invention, the present invention provides a room-temperature solid-state polymer-based electrochemical hydrogen sensor prepared according to the preparation method of the room-temperature solid-state polymer-based electrochemical hydrogen sensor.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The room-temperature solid-state polymer-based electrochemical hydrogen sensor designed in this invention exhibits good selectivity, high sensitivity, low cost, small size, and can be integrated and mass-produced, while also operating at room temperature. Furthermore, compared to liquid electrolytes, this solid-state polymer-based electrochemical hydrogen sensor requires neither an electrolyte nor a binder; only a solid polymer electrolyte film in close contact with the electrode is needed. When the target gas H2 reaches the electrode, an electrochemical reaction occurs, and H2 is generated on the working electrode. + By applying a solid polymer electrolyte film to the counter electrode, a response current is generated, allowing direct observation of the sensor's response to gas. The solid electrolyte replaces the liquid electrolyte for conducting H₂. + Therefore, it can effectively avoid problems such as liquid leakage that exist in traditional liquid electrolyte-based electrochemical sensors. Attached Figure Description

[0021] Figure 1 This is a synthetic route diagram of the room-temperature solid polymer electrolyte in Example 1 of the present invention;

[0022] Figure 2 This is a sample image of the room-temperature solid polymer electrolyte in Example 1 of the present invention;

[0023] Figure 3 This is a flowchart of the assembly process of the room temperature solid polymer-based electrochemical hydrogen sensor in Embodiment 2 of the present invention;

[0024] Figure 4 This is a current response diagram of the room-temperature solid polymer-based electrochemical hydrogen sensor in Embodiment 2 of the present invention to different gases;

[0025] Figure 5 This refers to the response current of the room-temperature solid polymer-based electrochemical hydrogen sensor in Embodiment 2 of the present invention to different concentrations of hydrogen.

[0026] Figure 6 This is the response current of the room temperature solid polymer-based electrochemical hydrogen sensor in Embodiment 2 of the present invention to 50 ppm hydrogen at different temperatures with 55% humidity;

[0027] Figure 7 The room-temperature solid polymer-based electrochemical hydrogen sensor in Example 2 of this invention provides the response current of 50 ppm hydrogen gas at 25°C and different humidity levels.

[0028] Figure 8 The response recovery time of the room temperature solid polymer-based electrochemical hydrogen sensor in Example 2 of this invention under a single response of 50 ppm hydrogen at 25°C and 55% humidity.

[0029] Figure 9 This refers to the response recovery time of the room-temperature solid polymer-based electrochemical hydrogen sensor in the comparative example of this invention under conditions of 25°C and 55% humidity for a single response to 50 ppm hydrogen. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] Depend on Figure 1 As shown, the preparation method of room-temperature solid polymer electrolyte includes the following steps:

[0033] Step 1: Add 0.55g of polyvinylidene fluoride (PVDF) powder to 3.2g of N,N-dimethylformamide (DMF) solution and stir for 2 hours to form a homogeneous solution. Pour 4mL of the homogeneous solution into a petri dish, and then place the petri dish in an oven and dry it at 60℃ for 2 hours to form a film, which is called the PVDF base film with a thickness of 0.08mm.

[0034] Step 2: Prepare 50 mL of 0.1 mol / L sodium hydroxide-ethanol solution, immerse the PVDF substrate membrane in it, alkalize it at 70 °C for 70 min, then remove it and wash it with deionized water until neutral.

[0035] Step 3: Prepare a mixed solution of 0.35g benzoyl peroxide, 10mL tetrahydrofuran and 40mL styrene. Place the membrane washed in Step 2 into the solution and carry out the grafting reaction in a water bath at 70℃ for 16h to obtain a polyvinylidene fluoride-grafted polystyrene membrane. Then, place it in dichloromethane to swell for 2h.

[0036] Step 4: Place the swollen membrane from Step 3 into concentrated sulfuric acid and perform a sulfonation reaction at 70°C for 8 hours to obtain a polyvinylidene fluoride-grafted polystyrene sulfonate membrane (PVDF-g-PSSA) with a thickness of 0.20 mm, which is the room-temperature solid polymer electrolyte. Figure 2 As shown.

[0037] Example 2

[0038] A method for preparing a room-temperature solid polymer electrolyte-based electrochemical hydrogen sensor includes the following steps:

[0039] Step 1: Prepare the Pt / C working electrode. Mix 12 mg Pt / C with 2 μL deionized water, 3 μL isopropanol, and 4 μL Nafion solution. Sonicate for 10 minutes to obtain a uniformly dispersed Pt / C slurry. Apply the slurry to the working and reference electrodes of the substrate using a glass pen to a thickness of 0.1 mm. Then, dry the substrate in an 80°C oven for 1 hour.

[0040] Step 2: According to Figure 3 The sensor is assembled using the method shown, with Pt / C as the working electrode and reference electrode, Pt as the counter electrode, and a polyvinylidene fluoride-grafted polystyrene sulfonic acid membrane as the electrolyte. The PVDF-g-PSSA film prepared in Example 1 is cut into pieces 8 mm long and 8 mm wide, and placed over the electrode area (the working electrode, counter electrode, and reference electrode coated with Pt / C). The film is then fixed to the substrate with a clamp, ensuring the film adheres tightly to the substrate, thus obtaining the room-temperature solid polymer-based electrochemical hydrogen sensor.

[0041] The film was clamped to the substrate using a clamp to ensure complete contact between the electrode and the film. The clamp was then connected to the Chenhua CHI650E electrochemical workstation using a wire to test the electrochemical performance of the electrochemical hydrogen gas sensor using a PVDF-g-PSSA solid polymer film as the electrolyte.

[0042] Depend on Figure 4 As shown, at a temperature of 25°C and a humidity of 55%, the sensor in this embodiment exhibits the highest response value to hydrogen in the following gas mixtures: 2.5 ppm hydrogen (H2), acetone (C3H6O), hydrogen sulfide (H2S), nitrogen dioxide (NO2), carbon monoxide (CO), formaldehyde (HCHO), ethanol (C2H6O), ammonia (NH3), nitric oxide (NO), 5 ppm carbon dioxide (CO2), 7.5 ppm methane (CH4), and 3% oxygen (O2). This demonstrates that the electrochemical gas sensor has excellent selectivity for hydrogen.

[0043] Depend on Figure 5As shown, under the conditions of 25°C room temperature and 55% humidity, as the hydrogen concentration decreases from high to low, the response current value also decreases continuously. At low concentrations, even a change of 1 ppm of hydrogen can be detected and a corresponding current is generated.

[0044] Depend on Figure 6 As shown, under 55% humidity conditions, the response current value increases continuously with increasing temperature, while the response recovery time decreases continuously.

[0045] Depend on Figure 7 As shown, at room temperature of 25℃, the response current value first increases and then decreases as humidity increases, and the response recovery time is continuously shortened. Furthermore, the optimal humidity range for the electrochemical gas sensor is 50%-60%, at which point the generated response current is more pronounced.

[0046] Depend on Figure 8 As shown, under room temperature conditions of 25°C and humidity of 55%, the single response time to 50 ppm hydrogen is 96 s and the recovery time is 54 s.

[0047] Comparative Example

[0048] A method for preparing a room-temperature solid-state polymer electrolyte-based electrochemical hydrogen sensor using a non-noble metal-based catalyst to replace commercially available Pt / C as the electrode material includes the following steps:

[0049] Step 1: Preparation of the non-precious metal-based catalyst Fe-AC. 20 mg of Fe-AC was mixed with 1 μL of deionized water, 3 μL of isopropanol, and 0.5 μL of solution. The mixture was ultrasonically vibrated for ten minutes to obtain a uniformly dispersed Fe-AC slurry. This slurry was then coated onto the working and reference electrodes of the substrate using a glass pen to a thickness of 0.08 mm. The substrate was then dried in an 80°C oven for 0.3 h.

[0050] Step 2: Using Fe-AC as the working electrode and reference electrode, Pt as the counter electrode, and a polyvinylidene fluoride-grafted polystyrene sulfonic acid membrane as the electrolyte, the PVDF-g-PSSA film prepared in Example 1 is cut into pieces 8 mm long and 8 mm wide. These pieces are then used to cover the electrode area (the working electrode, counter electrode, and reference electrode coated with Fe-AC). The film is then fixed to the substrate using a clamp, ensuring the film adheres tightly to the substrate, thus obtaining the room-temperature solid polymer-based electrochemical hydrogen sensor.

[0051] The film was clamped to the substrate using a clamp to ensure complete contact between the electrode and the film. The clamp was then connected to the Chenhua CHI650E electrochemical workstation using a wire to test the electrochemical performance of the electrochemical hydrogen gas sensor using a PVDF-g-PSSA solid polymer film as the electrolyte.

[0052] Depend on Figure 9 As shown, under room temperature conditions of 25°C and humidity of 55%, the single response time to 50 ppm hydrogen is 9.3 s and the recovery time is 8.1 s.

[0053] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor, characterized in that, Includes the following steps: Using Pt / C as the working electrode and reference electrode, Pt as the counter electrode, and room temperature solid polymer electrolyte as the electrolyte, the room temperature solid polymer electrolyte is cut and the room temperature solid polymer electrolyte film is uniformly covered on the Pt / C working electrode by extrusion method to obtain the room temperature solid polymer-based electrochemical hydrogen sensor. The preparation method of the room-temperature solid polymer electrolyte includes the following steps: Step 1: Mix polyvinylidene fluoride powder with N,N-dimethylformamide solution at room temperature to form a homogeneous solution, and then dry to obtain PVDF base film; Step 2: Chemically modify the PVDF base membrane. First, alkalize the PVDF base membrane to generate carbon-carbon double bonds. Then, graft polystyrene onto the PVDF. Finally, sulfonate it with concentrated sulfuric acid to obtain a polyvinylidene fluoride-grafted polystyrene sulfonic acid membrane, which is the room temperature solid polymer electrolyte. The reagent used for alkalization is sodium hydroxide-ethanol solution.

2. The method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor according to claim 1, characterized in that: In step 1, the mass ratio of polyvinylidene fluoride to N,N-dimethylformamide is 15:85, the drying temperature is 60-70℃, the drying time is 1-2h, and the film thickness is 0.08-0.13mm.

3. The method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor according to claim 1, characterized in that: In step 2, the alkalization temperature is 70°C and the alkalization time is 70 min.

4. The method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor according to claim 1, characterized in that: In step 2, the grafting step is as follows: the PVDF base film after alkalization is washed and placed in a mixture of benzoyl peroxide, tetrahydrofuran and styrene, and the grafting reaction is carried out in a water bath at 70°C for 12-16 hours to obtain a polyvinylidene fluoride-grafted polystyrene film, which is then placed in dichloromethane for swelling for 1-2 hours.

5. The method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor according to claim 1, characterized in that: In step 2, the sulfonation temperature is 70-80℃ and the sulfonation time is 8-12h.

6. The method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor according to claim 1, characterized in that: The Pt / C working electrode is prepared as follows: Pt / C, deionized water, isopropanol and Nafion solution are mixed into a uniform slurry, which is then applied to the working electrode and reference electrode of the substrate with a glass pen and dried for later use.

7. The method for preparing a room-temperature solid-state polymer-based electrochemical hydrogen sensor according to claim 6, characterized in that: The volume ratio of deionized water, isopropanol, and Nafion solution is 2:3:4, the Pt / C content is 1.33 g / mL, the coating thickness is 0.05-0.1 mm, the drying temperature is 60-80℃, and the drying time is 0.5-1 h.

8. A room-temperature solid-state polymer-based electrochemical hydrogen sensor prepared by the method described in any one of claims 1-7.

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