Vanadium pentoxide nanoflower-based gas sensor as well as preparation method and application thereof

Abstract

The invention discloses a gas sensitive sensor based on vanadium pentoxide nanoflowers and a preparation method and application thereof.A vanadium pentoxide nanoflower material is prepared through a simple hydrothermal method, the V2O5 nanoflower material is ground to be pasty and then coated on a ceramic substrate with an Au interdigital electrode deposited on the surface, and the gas sensitive sensor based on the vanadium pentoxide nanoflowers is obtained. The gas sensitive sensor based on the vanadium pentoxide nanoflower material is obtained. The vanadium pentoxide nanoflower structure prepared by the invention has abundant oxygen vacancies and a relatively large specific surface area, provides more active adsorption sites for chemical adsorption of oxygen and target gas, and is beneficial to improvement of gas-sensitive performance. The sensor has certain sensitivity and selectivity to hydrogen at a low temperature, is short in response and recovery time, has excellent long-term stability, and has certain application prospects in the fields of lithium ion battery thermal runaway detection, early warning and the like.

Description

Technical Field

[0001] The present invention belongs to the field of gas sensors, and relates to a gas-sensitive sensor based on vanadium pentoxide nanoflowers, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasing energy demand and the popularization of electric vehicles, lithium-ion batteries are increasingly widely used in various portable devices and electric vehicles. However, during the use of lithium-ion batteries, factors such as battery performance degradation, overcharging and discharging, and high temperature may cause battery failure, and even dangerous situations such as battery short circuit, overheating, and swelling may occur. In these cases, gases such as hydrogen may be released, posing potential safety hazards. Therefore, the real-time detection of hydrogen is crucial for battery safety.

[0003] In the present invention, it is found that V2O5 can be used as a hydrogen sensor during the thermal failure of the battery because of its high sensitivity, high selectivity, fast response, and certain stability to hydrogen. The V2O5 with nanoflower structure prepared in the present invention has a larger specific surface area, thus providing more adsorption sites for hydrogen, accelerating the response to hydrogen, and improving the gas-sensitive performance to hydrogen to a certain extent. Summary of the Invention

[0004] To solve the above problems, the present invention provides a gas-sensitive sensor based on vanadium pentoxide nanoflowers, a preparation method thereof, and an application thereof. The sensor of the present invention is based on V2O5 nanoflower material, has certain sensitivity and selectivity, fast response, and good long-term stability, and is expected to be used for the detection of H2 before battery thermal failure.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A preparation method of a gas-sensitive sensor based on vanadium pentoxide nanoflowers, comprising the following steps:

[0007] (1) Ammonium metavanadate and oxalic acid dihydrate are mixed and dissolved with water and ethanol to obtain a precursor solution;

[0008] (2) The precursor solution is transferred to a polytetrafluoroethylene reaction kettle and placed in an oven for hydrothermal reaction to obtain precursor nanoflowers.

[0009] (3) The precursor nanoflowers are dried and annealed to obtain V2O5 nanoflower material;

[0010] (4) The V2O5 nanoflower material is ground into a paste and then coated on a ceramic substrate with an Au interdigital electrode deposited on the surface, thereby obtaining a gas-sensitive sensor based on vanadium pentoxide nanoflower material, and the gas-sensitive sensor is used for detecting H2.

[0011] Further, in step (1), the dosage ratio of ammonium metavanadate, oxalic acid dihydrate, water and ethanol is 1 g: 1.27 - 1.31 g: 24 - 26 ml: 48 - 52 ml.

[0012] Further, in step (2), the heating temperature of the hydrothermal reaction is 180 °C and the time is 6 h.

[0013] Further, in step (3), the drying is vacuum drying.

[0014] Further, in step (3), the parameters of the annealing are: heating rate 1 - 2 °C / min, calcination time 2 h, and calcination temperature 300 - 350 °C.

[0015] Further, in step (4), the ceramic substrate is specifically an alumina ceramic substrate.

[0016] A gas sensor based on vanadium pentoxide nanoflowers is obtained by using any one of the above preparation methods.

[0017] Further, the response value of the gas sensor to 100 ppm of H2 gas at 100 °C is 1.83, and the response time is 20 s.

[0018] Further, the gas sensor is placed in an oven, and the drying temperature is 60 °C and the drying time is 24 h to achieve the purpose of aging, making the performance of the sensor more stable.

[0019] The application of the gas sensor in the field of early warning of thermal runaway of lithium-ion batteries.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The vanadium pentoxide nanoflower material proposed by the present invention as a gas-sensitive material has a high surface area and abundant oxygen vacancies. Its unique nanostructure can provide more reversible active adsorption / reactivity sites, making an important contribution to accelerating the redox reaction and achieving the response to H2, thereby improving the gas-sensing performance.

[0022] (2) The preparation method of the present invention is simple and controllable, the process conditions are mild, the energy consumption is low, the production cycle is short, the requirements for equipment are low, there is no pollution to the environment, its preparation method is simple and the cost is low, and it is suitable for large-scale preparation.

[0023] (3) The gas sensor provided by the present invention based on the vanadium pentoxide nanoflower material has a response value of 1.83 to 100 ppm of H2 gas at 100 °C, and the response time is 20 s. In addition, the sensor based on V2O5 nanoflowers has certain selectivity and long-term stability.

[0024] (4) The vanadium pentoxide nanoflower material provided by the present invention is expected to be applied to the detection of H2 before the thermal failure of the battery. Description of the Drawings

[0025] Figure 1 It is the XRD pattern of the V2O5 nanoflower material in the embodiment of the present invention;

[0026] Figure 2 It is the SEM pattern of the V2O5 nanoflower material in the embodiment of the present invention;

[0027] Figure 3 It is the further enlarged SEM pattern of the V2O5 nanoflower material in the embodiment of the present invention;

[0028] Figure 4 It is the working temperature test pattern of the V2O5 nanoflower gas sensor for hydrogen in the embodiment of the present invention.

[0029] Figure 5 It is the cyclic test pattern of the V2O5 nanoflower gas sensor for 100 ppm hydrogen concentration at the optimal working temperature in the embodiment of the present invention;

[0030] Figure 6 It is the gas selectivity test pattern of the V2O5 nanoflower gas sensor at the optimal working temperature in the embodiment of the present invention;

[0031] Figure 7 It is the long-term stability test pattern of the V2O5 nanoflower gas sensor at the optimal working temperature in the embodiment of the present invention. Detailed Embodiments

[0032] The technical solutions of the present invention will be further described below in conjunction with the drawings and specific embodiments, but are not limited thereto.

[0033] Embodiment

[0034] (1) Preparation of the precursor solution: Weigh 0.585 g of ammonium metavanadate and 0.755 g of oxalic acid dihydrate and dissolve them in a mixed solution of 30 mL of deionized water and 15 mL of ethanol, stir for 3 h, and set the stirring speed to 300 rpm / min to obtain the precursor solution.

[0035] (2) Hydrothermal reaction: Transfer the above precursor solution to a 50 mL polytetrafluoroethylene reaction kettle, place it in an oven for hydrothermal reaction, and set the conditions to react at 180 °C for 6 h. After the reaction, the precursor nanoflowers are obtained.

[0036] (3) Preparation of nanoflowers: The obtained precursor nanoflowers were dried in a vacuum drying oven at a temperature of 90 °C for 6 h. Then, the dried precursor was cut into small pieces with scissors and annealed in a tube furnace at a temperature of 350 °C for 2 h with a heating rate of 2 °C / min. After natural cooling to room temperature, the obtained V2O5 nanoflowers were collected.

[0037] (4) Preparation of gas sensors: 50 mg of the prepared V2O5 nanoflower sample was weighed and placed in an agate mortar. 0.5 mL of ethanol was added and thoroughly ground until a paste-like slurry was formed. The slurry was coated on an alumina ceramic substrate with a deposited Au interdigital electrode to obtain a gas sensor. Subsequently, the prepared gas sensor was placed in an oven and dried at a temperature of 60 °C for 24 h for aging purposes to make the performance of the sensor more stable.

[0038] Gas sensing test:

[0039] The obtained samples were subjected to gas sensing measurements using an intelligent gas sensing analysis system: a micro multi-functional detection station CGS-MT for detection, with a certain amount of H2 or dry air alternately filled in the cavity, and a gas-liquid distribution system DGL-Ⅴ with automatic humidity control. During the operation, the test device was first placed in the center of the heating stage to stabilize its resistance in an air atmosphere. In a typical test, nitrogen was first introduced into the pneumatic valve to open the valve in the device. The humidity was dynamically controlled by a dual-flow dynamic humidity generator DHD-Ⅱ. The response value was defined as the ratio of the resistance R of the gas sensor in the air background to the resistance R in the target gas H2 environment; the response time and the recovery time were defined as the time required for a 90% change in the resistance value during the response and recovery processes. a and the resistance R in the target gas H2 environment g The ratio; the response time and the recovery time were defined as the time required for a 90% change in the resistance value during the response and recovery processes.

[0040] Result analysis:

[0041] (1) XRD analysis: The crystal structure of the V2O5 nanoflower material was studied by XRD. As Figure 1 shown, all the diffraction peaks in the XRD pattern had good correlation with α-V2O5. No diffraction peaks of other impurities were observed in the XRD pattern, indicating that the sample obtained by the hydrothermal method had a high purity. The main characteristic peaks were at 2θ = 15.379°, 20.303°, 21.734°, 26.143°, 31.067°, 32.327°, 34.331°, 47.327° and 51.221°, corresponding to the (200), (001), (101), (110), (400), (011), (310), (600) and (020) planes of the V2O5 crystal, respectively, which was in line with the standard card (PDF#04-007-0398).

[0042] (2) SEM analysis: Analyze the morphology, composition, and elemental types of the V2O5 nanoflower material. As Figure 2 and Figure 3 shown in the SEM image of V2O5 in, the shape of V2O5 is a nanoflower composed of nanosheets. The average diameter of the nanoflower is about 5 μm, and the average length of the nanosheets is also 5 μm. The larger nanosheets are beneficial to the diffusion and transmission of gas molecules. At the same time, the larger specific surface area of the nanoflower also provides more adsorption sites for hydrogen.

[0043] (3) Gas sensing performance: As Figure 4 shown, the V2O5 nanoflower sensor was subjected to gas sensing tests for 100 ppm H2 at 50 °C, 100 °C, 150 °C, 200 °C, 250 °C, and 300 °C, respectively, and the response values were 1.15, 1.83, 1.5, 1.47, 1.21, and 1.04, respectively. Therefore, the optimal operating temperature of the V2O5 nanoflower sensor for 100 ppm H2 should be 100 °C. As Figure 5 shown, the V2O5 nanoflower sensor shows that when exposed to an H2 environment, the resistance value immediately decreases; when the sensor enters an air environment, the resistance value gradually increases. At the optimal operating temperature of 100 °C, the response value of the V2O5 nanoflower sensor to 100 ppm H2 is 1.83, and the response time is 20 s. Figure 6 The gas selectivity of the V2O5 nanoflower-based sensor was studied by exposing it to 100 ppm H2 or interfering gases such as acetone, NO2, ethanol, etc. The V2O5 nanoflower-based sensor has the best response to H2. Figure 7 shows the long-term stability of the V2O5 nanoflower-based sensor to 100 ppm H2. The response of the sensor did not change significantly within 28 days and remained within a stable range.

[0044] The above-described embodiments have detailed the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, supplements, equivalent replacements, etc. made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation method of a gas sensor based on vanadium pentoxide nanoflowers, characterized in that It includes the following steps: (1) Mix ammonium metavanadate and oxalic acid dihydrate with water and ethanol and dissolve them to obtain a precursor solution; (2) Transfer the precursor solution to a polytetrafluoroethylene reaction kettle, place it in an oven for hydrothermal reaction to obtain precursor nanoflowers; (3) Dry and anneal the precursor nanoflowers to obtain a V2O5 nanoflower material composed of nanosheets; (4) Grind the V2O5 nanoflower material into a paste and coat it on a ceramic substrate with Au interdigital electrodes deposited on the surface, thus obtaining a gas sensor based on the vanadium pentoxide nanoflower material, and the gas sensor is used to detect H2.

2. The preparation method according to claim 1, characterized in that, In step (1), the dosage ratio of ammonium metavanadate, oxalic acid dihydrate, ethanol and water is 1 g: 1.27 - 1.31 g: 24 - 26 ml: 48 - 52 ml.

3. The preparation method according to claim 1, characterized in that, In step (2), the heating temperature of the hydrothermal reaction is 180 - 190 °C and the time is 6 - 8 h.

4. The preparation method according to claim 1, characterized in that, In step (3), the drying is vacuum drying.

5. The preparation method according to claim 1, characterized in that, In step (3), the parameters of the annealing are: heating rate 1 - 2 °C / min, calcination time 1 - 2 h, and calcination temperature 300 - 350 °C.

6. The preparation method according to claim 1, characterized in that, In step (4), the ceramic substrate is an alumina ceramic substrate.

7. A gas sensor based on vanadium pentoxide nanoflowers, characterized in that, Obtained by using the preparation method according to any one of claims 1 - 6.

8. The gas sensor according to claim 7, characterized in that, The gas sensor has a response value of up to 1.83 to 100 ppm of H2 gas at 100 °C, and the response time is 20 s.

9. The gas sensor according to claim 7, characterized in that, The gas sensor is placed in an oven, and the drying temperature is 60 - 90 °C and the drying time is 10 - 24 h to achieve the purpose of aging, so that the performance of the sensor is more stable.

10. Application of the gas sensor according to claim 7 in the field of early warning of thermal runaway of lithium - ion batteries.

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