A H2 sensor material based on SnO2-doped graphene aerogel and its preparation method

Abstract

The present invention discloses a H2 sensor material based on SnO2-doped graphene aerogel and a preparation method. The material comprises mixing graphene oxide with N,N-dimethylformamide and water to form a mixed solution, adding the mixed solution to a tin salt solution, performing a solvothermal heat treatment, and then calcining the solution in a muffle furnace. The present invention dopes the graphene aerogel with SnO2 nanoparticles. The graphene aerogel structure modifies the operating characteristics of the tin dioxide material, resulting in a sensor material with high gas sensitivity, good selectivity, and stability. This reduces the sensor's operating temperature and device power consumption, resulting in ultrahigh sensitivity, anti-interference performance, and good resistance to electrolyte corrosion. The material has broad application prospects in the future field of thermal runaway early warning technology for lithium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to an H2 sensor material based on SnO2-doped graphene aerogel and a preparation method thereof. Background Art

[0002] Resource shortages and environmental degradation are forcing the search for new, environmentally friendly alternative energy sources. Lithium-ion batteries (LIBs) have become a major research focus in energy storage technology due to their advantages, including high operating voltage, high specific capacity, long cycle life, and minimal self-discharge. However, LIB safety still presents significant risks, necessitating the development of early warning and real-time monitoring technologies for battery safety. Theoretical studies have shown that thermal runaway in LIBs is accompanied by numerous side reactions and the release of numerous gases, primarily hydrogen, carbon monoxide, carbon dioxide, methane, and ethylene.

[0003] In the sensor field, semiconductor metal oxide nanosheets (particularly SnO2) have rapidly expanded across various market sectors since their development, garnering widespread attention worldwide due to their high specific surface area and specific crystal interface exposure. However, the application of SnO2 gas sensors in LIBs has been largely unstudied. Application of SnO2 gas-sensitive materials in lithium-ion batteries is not only susceptible to electrolyte corrosion, but also suffers from high operating temperatures that do not meet the gas sensing requirements of lithium-ion batteries. Overcoming these technical challenges is currently a key research topic for researchers. Summary of the Invention

[0004] The object of the present invention is to provide an H2 sensor material based on SnO2-doped graphene aerogel and a preparation method thereof to solve the problems raised in the background technology in order to address the above-mentioned problems.

[0005] The technical solution adopted by the present invention is as follows: a preparation method of an H2 sensor material based on SnO2-doped graphene aerogel, comprising mixing graphene oxide with N,N-dimethylformamide and water to form a mixed solution, adding the mixed solution to a tin salt solution, performing a solvothermal heat treatment, and then calcining the mixed solution in a muffle furnace.

[0006] Furthermore, the mass ratio of N,N-dimethylformamide to water is 2-5:1, for example, 2:1, 3:1, 4:1, 5:1, etc.

[0007] Furthermore, in the mixed solution, the concentration of the tin salt is 0.5-1.5 mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.5 mol / L, etc.

[0008] Furthermore, in the mixed solution, the concentration of graphene oxide is 1-3 mg / mL.

[0009] Furthermore, the tin salt is preferably tin chloride dihydrate.

[0010] Furthermore, the preparation method of the above sensor material comprises the following steps:

[0011] A. Add tin salt to ethanol and stir evenly to obtain a tin salt solution;

[0012] B. mixing graphene oxide with stirred water, then adding N,N-dimethylformamide, and dispersing by ultrasonication to obtain a uniform mixed solution;

[0013] C. adding the mixed solution to the tin salt solution, stirring and mixing uniformly, and then heating in an oven using a solvothermal method to prepare a graphene hydrogel;

[0014] D. washing and soaking the obtained graphene hydrogel in deionized water, and then drying in a dryer to obtain a graphene aerogel;

[0015] E. Place the graphene aerogel in a muffle furnace and calcine it at 300-380° C. for 15-45 min to obtain the graphene aerogel.

[0016] Furthermore, in step C, after the mixed solution and the tin salt solution are evenly mixed, they are transferred to a reactor lined with polytetrafluoroethylene, the reactor is placed in an oven, the temperature of the oven is set to 150-250°C, and after heating for 4-8 hours, it is cooled to room temperature and taken out to obtain the graphene hydrogel.

[0017] Furthermore, the present invention also includes an H2 sensor material based on SnO2-doped graphene aerogel, and the H2 sensor material is prepared by the above-mentioned preparation method.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] 1. The H2 sensor material of the present invention is prepared by a solvothermal method. The preparation process is simple, easy to operate and low-cost. The prepared graphene aerogel with a three-dimensional void structure plays an important role in electron transfer. It has ultra-low density and ultra-high specific surface area, and at the same time has a rich pore structure and huge mechanical elasticity. It can prevent the aggregation and collapse of graphene sheets and fully allow the contact between gas and active sites. It also enhances the conductivity of the sensor material itself. Since tin dioxide materials usually require a higher operating temperature (above 200°C), the sensor power consumption is high and its application is limited. In the present invention, SnO2 nanoparticles are doped on the graphene aerogel. The working characteristics of the tin dioxide material are changed by the graphene aerogel structure, so that the sensor material has higher gas-sensing performance, better selectivity and stability, and reduces the operating temperature and device power consumption of the sensor. It has ultra-high sensitivity and anti-interference performance.

[0020] 2. In the present invention, graphene aerogel and SnO2 nanoparticles produce a unique synergistic effect, which not only enables the sensor to work efficiently at a lower temperature, but also significantly improves the chemical stability of the sensor material and has good electrolyte corrosion resistance, meeting the use requirements and solving the problem of material selection for electrolyte corrosion resistance of gas sensors built into lithium-ion batteries;

[0021] 3. The present invention uses the three-dimensional structure of graphene aerogel to increase the specific surface area of the material. The ultra-low density and mechanically elastic three-dimensional structure formed helps provide a stable multi-channel structure for electron transfer, accelerates the reaction between H2 gas and SnO2 nanosheets, and thus improves the response-recovery behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a scanning electron microscope (SEM) image of the SnO2 / rGO material prepared in Example 2;

[0023] Figure 2 is a transmission electron microscopy (TEM) image of the SnO2 / rGO material prepared in Example 2;

[0024] Figure 3 is the X-ray diffraction (XRD) pattern of the SnO2 / rGO material prepared in Example 2;

[0025] Figure 4 2 is a graph showing the response performance of the SnO2 / rGO materials prepared in Example 1 and Example 2 to 20-500 ppm H2 gas at 120°C;

[0026] Figure 5The response performance diagram of the SnO2 / rGO material prepared in Example 2 to five gases, namely H2, CO, C2H4, CH4 and CO2, at 20-500ppm at 120°C;

[0027] Figure 6 This is a bar graph of the response values of the SnO2 / rGO material prepared in Example 2 to two different concentrations and five different types of gases at 120°C. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings.

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the sensitivity test of the sensor of the present invention, the sensitivity S of the sensor is defined as ΔR / Ra, where Ra is the initial resistance of the sensor in argon, Rg is the resistance value of the sensor in the gas to be measured, and ΔR is the difference between the resistance of the device in argon and the resistance in the gas to be measured |Rg-Ra|.

[0031] Scanning electron microscope (SEM) test: The scanning electron microscope used was a JEOL IT-800 field emission scanning electron microscope from JEOL Ltd.

[0032] Gas sensing performance test: The test equipment used is the CGS-8 intelligent gas sensitive analysis system and DGD-V digital dynamic gas distribution system produced by Beijing Zhongju High-tech Technology Co., Ltd.

[0033] Example 1

[0034] A high-performance SnO2 / rGO gas sensor, the preparation method of which comprises the following steps:

[0035] S1. Clean and dry a commercially available flat-plate Au electrode (with extended platinum wire) with deionized water and ethanol, respectively. The electrode is equipped with a test electrode and a heating electrode. The electrode heating temperature can be controlled by adjusting the input current. The upper surface of the electrode is Au, which serves as the test end, and the lower surface is Ru, which serves as the heating end. The flat-plate electrode has an overall size of 1.5 × 1.5 mm.

[0036] S2. Add SnCl2·2H2O to ethanol and stir evenly until it is completely dissolved to obtain a tin salt solution;

[0037] S3, mixing the nano-scale flake graphene oxide with stirred water, then centrifuging, adding N,N-dimethylformamide (DMF), and ultrasonically dispersing to obtain a uniform mixed solution;

[0038] S4. Add the mixed solution to the tin salt solution and stir to mix evenly. At this time, the mass ratio of DMF to water is 5:1, the concentration of graphene is 2 mg / mL, and the concentration of tin chloride is 1 mol / L;

[0039] S5. After the mixed solution and the tin salt solution are evenly mixed, they are transferred to a stainless steel reactor lined with polytetrafluoroethylene. The stainless steel reactor is placed in an oven and heated to 180°C for 6 hours. The oven is then cooled to room temperature and taken out to obtain a graphene hydrogel material in situ doped with SnO2 nanoparticles, which is named SnO2 / Gas.

[0040] S6. Washing and soaking the obtained graphene hydrogel material in deionized water multiple times to remove impurities, and then critically drying the obtained graphene hydrogel in a freeze dryer to obtain a graphene aerogel;

[0041] S7, placing the graphene aerogel in a muffle furnace and calcining it at 360 °C for 30 min to obtain the sensor material, named SnO2 / rGO;

[0042] S8. Weigh a certain amount of SnO2 / rGO into an agate mortar, add deionized water, and grind vigorously for 5-10 minutes to uniformly grind the powder into a paste-like slurry;

[0043] S9, evenly apply the slurry on the flat Au electrode with a brush to form an electrode film that completely covers the Au electrode;

[0044] S10. Place the obtained electrode on an aging table and age it at 60°C for 24 hours.

[0045] Example 2

[0046] Example 2 is the same as Example 1, except that in step S4, the volume ratio of DMF to water is 2:1.

[0047] Example 3

[0048] Example 3 is the same as Example 1, except that in step S4, the volume ratio of DMF to water is 3:1.

[0049] like Figure 1 and Figure 2 As shown in Figure 2, it can be seen that the tin dioxide nanoparticles are evenly and densely covered on the graphene substrate. Figure 3 As shown, from Figure 3 It can be seen that the peak of the prepared tin dioxide nanoparticles can accurately correspond to PDF card 41-1445, proving the successful preparation of tin dioxide.

[0050] like Figure 4 As shown, from Figure 4 It can be seen that at a temperature of 120°C, when performing gas-sensitive response to 20-500ppm of hydrogen, the SnO2 / rGO materials of Examples 1 and 2 both exhibited excellent high sensitivity performance, indicating that the SnO2 / rGO material of the present invention can exhibit excellent sensitivity to gas at an operating temperature below 200°C, overcoming the defect that the existing tin dioxide material needs to exhibit qualified sensitivity at an operating temperature above 200°C. At the same time, by comparison, it is found that the SnO2 / rGO material of Example 2 is more sensitive to hydrogen than the SnO2 / rGO material of Example 1, which shows that the mass ratio of DMF to water affects the structure of the SnO2 / rGO material, thereby affecting its sensitivity to hydrogen, and its sensitivity gradually declines with the increase in the amount of DMF used.

[0051] like Figure 5 As shown, from Figure 5 It can be seen that under the same environmental conditions, the SnO2 / rGO material has different resistance responses to different gases (hydrogen, carbon monoxide, ethylene, methane and carbon dioxide) and different gas concentrations (20-500ppm). Its sensitivity to hydrogen is the highest, indicating that it has good selectivity. Figure 6 As shown, Figure 6 It is proved that the SnO2 / rGO material of Example 2 has the largest response value to hydrogen, which can reach 75.5% / 25.1%, and has almost no response to carbon dioxide and methane. This shows that the SnO2 / rGO material prepared by the present invention has a high selectivity for hydrogen gas and can be used to detect H2 generated after thermal runaway inside lithium-ion batteries to achieve the purpose of early warning.

[0052] Comparative Example 1

[0053] Comparative Example 1 is the same as Example 1, except that in step S4, the concentration of tin chloride is 2 mol / L.

[0054] Comparative Example 2

[0055] Comparative Example 2 is the same as Example 1, except that in step S5, the temperature of the oven is 300°C.

[0056] Comparative Example 3

[0057] Comparative Example 3 is the same as Example 1, except that in step S7, the calcination temperature is 400°C.

[0058] Electrolyte corrosion and intrusion resistance test

[0059] The sensor corrosion test was conducted by placing the prepared sensor and electrolyte in an oven under an argon atmosphere. To maintain consistency with the internal battery environment, the electrolyte volume was set to 10 mL, in accordance with power battery specifications. Sensor corrosion tests were conducted at 25°C. The samples tested were Example 2 and Comparative Examples 2-4.

[0060] The test results show that the sensor prepared in Example 2 maintained good H2 sensing performance after corrosion, with its sensitivity to H2 at 50ppm and 100ppm remaining at 38.4% and 47.5%, respectively, a total decrease of 5.1%. For Comparative Example 1, the sensitivity to H2 at 50ppm and 100ppm decreased from 36.7% and 45.2% to 32.8% and 39.1%, respectively, before and after the corrosion test, a total decrease of 10%. This indicates that excessive tin can reduce the gas-sensitive material's corrosion resistance to electrolytes. For Comparative Example 2, the sensitivity to H2 at 50ppm and 100ppm decreased from 39% and 48.5% to 25.6% and 31.9%, respectively, a total decrease of 30%. This indicates that excessively high oven temperatures can affect the three-dimensional structure of the gas-sensitive material, leading to poor resistance to electrolyte corrosion. For Comparative Example 3, the sensitivity to 50ppm and 100ppm H2 before and after the corrosion test decreased from 37.3% and 48.1% to 23.4% and 30.2%, a decrease of 31.8%. This shows that too high a calcination temperature will also affect the three-dimensional structure of the gas-sensitive material, resulting in poor resistance to electrolyte corrosion.

[0061] Furthermore, the above test results show that the SnO2 / rGO material prepared by the present invention still maintains a certain sensitivity to hydrogen after being corroded by the electrolyte, which proves that the gas-sensitive material has excellent resistance to electrolyte corrosion and has broad application prospects in the field of thermal runaway warning technology of lithium-ion batteries in the future.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a H2 sensor material based on SnO2-doped graphene aerogel, characterized in that: Graphene oxide is mixed with N,N-dimethylformamide and water to form a mixed solution, wherein the volume ratio of N,N-dimethylformamide to water is 2-5:1, the mixed solution is added to a tin salt solution, heat-treated by a solvothermal method, and then placed in a muffle furnace and calcined at 300-380° C. for 15-45 minutes to obtain the obtained product, wherein the concentration of the tin salt is 0.5-1.5 mol / L, and the graphene oxide is nano-scale sheet graphene oxide, and its concentration is 1-3 mg / mL.

2. The method for preparing a H2 sensor material based on SnO2-doped graphene aerogel according to claim 1, wherein: The tin salt is tin chloride dihydrate.

3. The method for preparing a H2 sensor material based on SnO2-doped graphene aerogel according to claim 1 or 2, characterized in that: The steps include: A. Add tin salt to ethanol and stir evenly to obtain a tin salt solution; B. mixing graphene oxide with stirred water, then adding N,N-dimethylformamide, and dispersing by ultrasonication to obtain a uniform mixed solution; C. adding the mixed solution to the tin salt solution, stirring and mixing uniformly, and then heating in an oven using a solvothermal method to prepare a graphene hydrogel; D. washing and soaking the obtained graphene hydrogel in deionized water, and then critically drying the resultant graphene aerogel in a freeze dryer; E. Place the graphene aerogel in a muffle furnace and calcine it at 300-380° C. for 15-45 min to obtain the graphene aerogel.

4. The method for preparing a H2 sensor material based on SnO2-doped graphene aerogel according to claim 3, wherein: In step C, after the mixed solution and the tin salt solution are evenly mixed, they are transferred to a reactor lined with polytetrafluoroethylene, the reactor is placed in an oven, the oven temperature is set to 150-250° C., after heating for 4-8 hours, cooled to room temperature, and taken out to obtain graphene hydrogel.

5. A H2 sensor material based on SnO2-doped graphene aerogel, characterized in that: The H2 sensor material is prepared by the preparation method described in any one of claims 1 to 4.

Images