Gas sensor based on bismuth trioxide and dimethyl carbonate and preparation method
Through a gas sensor based on bismuth trioxide dimethyl carbonate, the interaction between nanosheet bismuth trioxide film and oxygen vacancies in DMC gas is utilized to achieve high-sensitivity detection of DMC gas in the early stage of battery thermal runaway, solving the problem of difficulty in early detection in existing equipment and providing early warning capabilities.
Patent Information
- Application Number
- CN202510903826.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-09-09
AI Technical Summary
Existing gas detection equipment such as gas chromatographs and mass spectrometers are large and expensive, making it difficult to accurately detect early thermal runaway of lithium batteries. Traditional commercial gas sensors are unable to detect DMC gas in the early stages of battery thermal runaway in a timely manner.
A gas sensor based on bismuth trioxide dimethyl carbonate is used. A P-type semiconductor structure is formed by coating a nano-sheet bismuth trioxide film on an insulating ceramic sheet. The DMC gas generated in the early stage of battery thermal runaway is detected by utilizing the interaction between DMC gas and oxygen vacancies on the Bi2O3 surface.
It achieves high-sensitivity detection of DMC gas in the early stage of battery thermal runaway, and can be detected when the battery surface temperature is only 42°C, which is more than 15 minutes earlier than H2 and CO, and has the ability to provide early warning of battery thermal runaway.
Smart Images
Figure CN120609872A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of gas sensors, and in particular to a bismuth trioxide-dimethyl carbonate-based gas sensor and a preparation method thereof. Background Art
[0002] Lithium iron phosphate (LFP) batteries are considered one of the most ideal energy storage media in power systems, and their safe operation is a key factor influencing their large-scale application. The safe operation of lithium batteries primarily relies on the battery management system (BMS). However, due to the large number of cells, it is difficult for the BMS to accurately estimate the status of each cell. To provide timely warning of thermal runaway in lithium batteries, an effective characteristic parameter must be selected for detection.
[0003] Among many characteristic parameters, gas parameters exhibit the ability to provide early warning of thermal runaway in lithium batteries compared to other parameters. While gas chromatographs and mass spectrometers can accurately detect volatile gases in the electrolyte, they are typically bulky and expensive, making it difficult to monitor gas production in each battery cell. Semiconductor gas sensors offer the advantages of high sensitivity, low price, and miniaturization. Integrating semiconductor gas sensors into each battery pack enables detection of released gases.
[0004] Traditional commercial gas sensors primarily detect hydrogen or carbon monoxide, which are generated early after battery thermal runaway, thereby providing an early warning of electromagnetic thermal runaway. However, research has shown that hydrogen and carbon monoxide are not the first gases released during thermal runaway. Instead, DMC gas, produced by the decomposition of an electrolyte, is released much earlier. DMC gas is composed of dimethyl carbonate (CH3OCOOCH3). It has been verified that DMC gas is released at least 15 minutes earlier than hydrogen or carbon monoxide. Therefore, early detection of DMC gas allows for earlier prevention and control of thermal runaway. Summary of the Invention
[0005] The present invention aims to provide a gas sensor based on bismuth trioxide dimethyl carbonate, so as to detect battery thermal runaway earlier than the current detection method of hydrogen or carbon monoxide. In addition, the present invention also provides a method for preparing a gas sensor based on bismuth trioxide dimethyl carbonate. The gas sensor manufactured by this method has very high detection sensitivity to DMC gas.
[0006] To achieve the above-mentioned object, the present invention adopts the following technical solution: a gas sensor based on bismuth trioxide dimethyl carbonate, comprising a base, an insulating ceramic sheet, a first electrode, and a second electrode; the insulating ceramic sheet is fixed on the base, the first electrode and the second electrode are arranged non-contact on the surface of the insulating ceramic sheet, and the surface of the insulating ceramic sheet is covered with a layer of 1 μm-5 μm nano-sheet bismuth trioxide film, the first electrode, the bismuth trioxide film, and the second electrode present a P-type semiconductor structure; the thickness of the bismuth trioxide nanosheet is less than or equal to 20 nanometers; the specific surface area is 30 m 2 / g-33 m 2 / g; oxygen vacancies account for 18%-25%.
[0007] The technical principles and beneficial effects of this solution: The gas sensor in this solution is used to detect the risk of thermal runaway in batteries. Its main function is to detect DMC gas produced by electrolyte decomposition in the early stages of thermal runaway. Its working principle is: the ester group C=O in the DMC gas directly interacts with the oxygen vacancies on the Bi2O3 surface. When the DMC gas reaches a certain level, the P-type semiconductor properties of the bismuth trioxide film make the sensor sensitive to DMC gas, and the resistance between the first electrode and the second electrode changes significantly. By measuring the change in the electrical signal reflected by the measuring circuit, the early detection of battery thermal runaway is achieved. Compared with traditional detection of H2 and CO gases released by the battery, the gas sensor in this solution can detect it when the battery surface temperature is only 42°C, more than 15 minutes earlier than H2 and CO.
[0008] In addition, the nano-sheet thickness of bismuth trioxide used in the gas sensor of this scheme is less than or equal to 20 nanometers; the specific surface area is 30 m 2 / g-33 m 2 / g; oxygen vacancies account for 18%-25%. The large specific surface area and abundant oxygen vacancies enhance gas adsorption and surface reactivity. A thickness of no more than 20 nanometers provides more active sites, further improving the sensitivity of this gas sensor, capable of detecting DMC gas down to 50 ppb.
[0009] In order to achieve high detection sensitivity for DMC gas in this solution, this solution provides a method for preparing a gas sensor based on bismuth trioxide and dimethyl carbonate, comprising the following steps: Step 1: dissolving bismuth nitrate pentahydrate in a mixed solvent consisting of ethanol and ethylene glycol, and stirring at room temperature to obtain a bismuth ion-containing solution; allowing the nitric acid pentahydrate to completely and quickly dissolve in the mixed solvent consisting of ethanol and ethylene glycol; Step 2: Transfer the solution from step 2 into a high-pressure reactor, and then place the high-pressure reactor at a temperature of 150-160° C. for a hydrothermal reaction; Step 3: Cooling the product after the hydrothermal reaction to room temperature, washing the material in the high-pressure reactor with deionized water and anhydrous ethanol multiple times, and then collecting the prepared material by centrifugation at a speed of 10,000 r / min to obtain nanosheet-shaped bismuth trioxide; Step 4: Grind the nanosheet-like bismuth trioxide into powder, add solvent and continue grinding until a paste-like slurry is formed, observe the microscopic morphology of bismuth trioxide, and select the nanosheet with a thickness of less than or equal to 20 nanometers and a specific surface area of 30 m 2 / g-33 m 2 / g; Bismuth trioxide paste slurry with an oxygen vacancy ratio of 18%-25%; Step 5: applying a bismuth trioxide paste slurry on the ceramic chip on which the first electrode and the second electrode are arranged, and forming a bismuth trioxide film, the first electrode, the bismuth trioxide film and the second electrode to form a P-type semiconductor structure; Step 6: Encapsulate the P-type semiconductor structure in step 5 into a gas sensor.
[0010] Preferably, in step 1, 12 mL of anhydrous ethanol and 6 mL of anhydrous ethylene glycol are required for every 0.3 g to 0.5 g of bismuth nitrate pentahydrate powder.
[0011] Preferably, in step 2, the reactor is a stainless steel high-pressure reactor, the inner wall of which is lined with Teflon ethylene.
[0012] Preferably, in step 4, the solvent added to the nano-sheet-shaped bismuth trioxide powder is terpineol.
[0013] Preferably, in step five, the bismuth trioxide paste is coated on the ceramic chip on which the first electrode and the second electrode are arranged to a thickness of 1 μm to 5 μm.
[0014] Preferably, in step five, the first electrode and the second electrode are gold electrodes, and the first electrode and the second electrode are arranged on the ceramic chip in a staggered non-contact arrangement.
[0015] Preferably, in step five, after applying the bismuth trioxide paste slurry on the ceramic chip on which the first electrode and the second electrode are arranged, drying is performed at a temperature of 80° C. for 30 minutes to form a bismuth trioxide film.
[0016] Preferably, after step six, the method further includes step seven, aging the packaged gas sensor. Specifically, the packaged gas sensor is placed on an aging table and the temperature is set to 60° C. until the resistance of the gas sensor reaches a stable value.
[0017] Preferably, in order to further determine the performance value of the gas sensor, step eight is also included, connecting the gas sensor of step seven to the measurement circuit, and placing the gas sensor in a test chamber, maintaining the chamber at room temperature, injecting 5~100ppm of DMC gas into the chamber, observing whether the resistance value of the gas sensor changes, then clearing the DMC gas in the chamber, and continuously injecting clean air, and observing again whether the gas sensor recovers its resistance value. After repeating the test 5~6 times, if the gas sensor has a change in resistance value, it indicates that the repeatability response performance of the gas sensor passes.
[0018] The advantages of adopting this scheme are: this method controls the use and ratio of solvents, selects appropriate temperature and reaction time, and achieves precise control of reaction conditions. The packaged gas sensor has high sensitivity to DMC gas. Experiments have shown that DMC gas with a concentration of 50ppb can be detected. Generally, the concentration of DMC gas released in the early stage of battery thermal runaway (about 15 minutes before the release of carbon monoxide and hydrogen) is much greater than 50ppb and can reach 500ppm. Therefore, the gas sensor prepared by this method has the ability to detect battery thermal runaway in the early stage. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a schematic diagram of the structure of the sensitive component of the gas sensor.
[0020] Figure 2 Flow chart for preparing a gas sensor capable of detecting DMC gas.
[0021] Figure 3 This is the microstructure diagram of bismuth trioxide nanosheets.
[0022] Figure 4 This is the characteristic curve of the gas sensor's sensitivity to DMC gas.
[0023] Reference numerals in the accompanying drawings of the specification include: insulating ceramic sheet 1 ; bismuth trioxide film 2 ; first electrode 31 ; second electrode 32 . DETAILED DESCRIPTION
[0024] The following is further described in detail through specific implementation methods: Example 1 Attachment Figure 1As shown: A gas sensor based on bismuth trioxide dimethyl carbonate, comprising a base, an insulating ceramic sheet 1, a first electrode 31 and a second electrode 32; the insulating ceramic sheet 1 is fixed on the base, the first electrode 31 and the second electrode 32 are arranged non-contact on the surface of the insulating ceramic sheet 1, and the surface of the insulating ceramic sheet 1 is covered with a layer of nano-sheet bismuth trioxide film 2, the thickness of the bismuth trioxide film is 1 μm-5 μm; the first electrode, the bismuth trioxide film and the second electrode present a P-type semiconductor structure; the thickness of the nano-sheet bismuth trioxide is less than or equal to 20 nanometers; the specific surface area is 30 m 2 / g-33 m 2 / g; oxygen vacancies account for 18%-25%.
[0025] Example 2 like Figure 2 As shown, a method for preparing a gas sensor based on bismuth trioxide and dimethyl carbonate comprises the following steps: Step 1 (S01): Dissolve bismuth nitrate pentahydrate in a mixed solvent of ethanol and ethylene glycol. Stir the mixed solution at room temperature for 15 minutes to obtain a bismuth ion solution. For every 0.3-0.5 g of bismuth nitrate pentahydrate powder, 12 mL of anhydrous ethanol and 6 mL of anhydrous ethylene glycol are required.
[0026] Step 2 S02: The solution was transferred to a stainless steel autoclave with a Teflon ethylene liner, and placed in an oven for hydrothermal reaction at 150-160° C. for 6 hours.
[0027] Step 3 S03: Cool the product after the hydrothermal reaction to room temperature, wash the material in the high-pressure reactor with deionized water and anhydrous ethanol 5 to 7 times, and then collect the prepared material by centrifugation at a speed of 10,000 r / min to obtain nano-sheet-shaped bismuth trioxide.
[0028] Step 4 S04: Grind the nano-sheet bismuth trioxide into powder, add solvent and continue grinding until a paste slurry is formed, observe the microscopic morphology of bismuth trioxide, and select the nano-sheet with a thickness of less than or equal to 20 nanometers and a specific surface area of 30m 2 / g-33 m 2 / g; bismuth trioxide paste slurry with an oxygen vacancy ratio of 18%-25%.
[0029] like Figure 3 As shown, the structure of the nano-sheet bismuth trioxide produced by steps 1 to 4 is shown in A~E forms, and the nano-sheet thickness is less than or equal to 20 nanometers; the specific surface area is 30 m 2 / g-33 m 2 / g, with oxygen vacancies accounting for 18%-25% of the nanosheet bismuth trioxide, Figure 3As can be seen from the figure, form C and form D meet the above requirements.
[0030] Step five S05: applying a bismuth trioxide paste slurry on the ceramic chip on which the first electrode and the second electrode are arranged to form a bismuth trioxide film. The first electrode, the bismuth trioxide film and the second electrode form a P-type semiconductor structure.
[0031] Step six S06: Encapsulate the P-type semiconductor structure in step five into a gas sensor.
[0032] Step seven S07, placing the packaged gas sensor on an aging table, setting the temperature at 60° C. for aging for 7 days, until the resistance of the gas sensor reaches a stable value.
[0033] Example 3 Perform performance test on gas sensor: The gas sensor that has completed aging in Example 2 is connected to the measurement circuit, and the gas sensor is placed in a test chamber. The chamber is maintained at room temperature, and 5~100ppm of DMC gas is injected into the chamber to observe whether the resistance value of the gas sensor changes. Then, the DMC gas in the chamber is cleared, and clean air is continuously injected. The gas sensor is observed again to see whether the resistance value recovers. After repeating the test 5~6 times, the gas sensor has a change in resistance, indicating that the repeatability response performance of the gas sensor passes.
[0034] Attachment Figure 4 The characteristic curve of the gas sensor shows that when the gas sensor is exposed to DMC gas concentrations of 5ppm, 10ppm, 20ppm, 50ppm, and 100ppm, its corresponding response values are 25.9%, 59.4%, 107.5%, 192.5%, and 295.7%, respectively. It can be concluded that the gas sensor can respond to DMC gas concentrations greater than 20ppm with a response greater than 100%.
[0035] The lower limit of DMC gas concentration that the gas sensor can respond to was tested, and it was found that the lowest DMC gas concentration that the gas sensor can respond to is 50ppb.
[0036] In this example, the gas sensor fabricated using this method was designed to detect DMC gas within a range of 10-500 ppm. Experimental results show that at 100 ppm of DMC gas, its sensitivity reaches 42.8 Ra / Rg (Rg is the sensor resistance in various gas concentrations, and Ra is the sensor resistance in clean air). The linearity is 0.992 R², where R² is the coefficient of determination for linear regression; a closer R² is to 1, the better the linearity. After 30 days, the sensitivity retention rate is 97.5%, the response time is 18 seconds, and the recovery time is 26 seconds.
[0037] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.
Claims
1. A bismuth trioxide-dimethyl carbonate-based gas sensor comprising a base, an insulating ceramic sheet, a first electrode, and a second electrode; the insulating ceramic sheet is fixed to the base, the first and second electrodes are arranged non-contactingly on the surface of the insulating ceramic sheet, and the surface of the insulating ceramic sheet is covered with a nano-sheet-like bismuth trioxide film; the first electrode, the bismuth trioxide film, and the second electrode exhibit a P-type semiconductor structure; the bismuth trioxide nanosheet has a thickness of 20 nanometers or less; and a specific surface area of 30 m 2 / g-33 m 2 / g; the proportion of oxygen vacancies is 18%-25%.
2. A method for manufacturing the gas sensor according to claim 1, characterized in that: The following steps are included: Step 1: dissolving bismuth nitrate pentahydrate in a mixed solvent consisting of ethanol and ethylene glycol, and stirring at room temperature to obtain a bismuth ion-containing solution; allowing the nitric acid pentahydrate to completely and quickly dissolve in the mixed solvent consisting of ethanol and ethylene glycol; Step 2: Transfer the solution from step 2 into a high-pressure reactor, and then place the high-pressure reactor at a temperature of 150-160° C. for a hydrothermal reaction; Step 3: Cooling the product after the hydrothermal reaction to room temperature, washing the material in the high-pressure reactor with deionized water and anhydrous ethanol multiple times, and then collecting the prepared material by centrifugation at a speed of 10,000 r / min to obtain nanosheet-shaped bismuth trioxide; Step 4: Grind the nanosheet-like bismuth trioxide into powder, add solvent and continue grinding until a paste-like slurry is formed, observe the microscopic morphology of bismuth trioxide, and select the nanosheet with a thickness of less than or equal to 20 nanometers and a specific surface area of 30 m 2 / g-33m 2 / g; Bismuth trioxide paste slurry with an oxygen vacancy ratio of 18%-25%; Step 5: applying a bismuth trioxide paste slurry on the ceramic chip on which the first electrode and the second electrode are arranged, and forming a bismuth trioxide film, the first electrode, the bismuth trioxide film and the second electrode to form a P-type semiconductor structure; Step 6: Encapsulate the P-type semiconductor structure in step 5 into a gas sensor.
3. The preparation method according to claim 2, wherein: In step 1, 12 mL of anhydrous ethanol and 6 mL of anhydrous ethylene glycol are required for every 0.3 g to 0.5 g of bismuth nitrate pentahydrate powder.
4. The preparation method according to claim 2, wherein: In step 2, the reactor is a stainless steel high-pressure reactor, the inner wall of which is lined with Teflon ethylene.
5. The preparation method according to claim 2, wherein: In step 4, the solvent added to the nano-sheet-shaped bismuth trioxide powder is terpineol.
6. The preparation method according to claim 2, wherein: In step five, a bismuth trioxide paste is coated on the ceramic chip on which the first electrode and the second electrode are arranged to a thickness of 1 μm to 5 μm.
7. The preparation method according to claim 6, characterized in that: In step five, the first electrode and the second electrode are gold electrodes, and the first electrode and the second electrode are arranged on the ceramic chip in a staggered non-contact arrangement.
8. The preparation method according to claim 7, characterized in that: In step five, a bismuth trioxide paste is applied on the ceramic chip on which the first electrode and the second electrode are arranged, and then dried at 80° C. for 30 minutes to form a bismuth trioxide film.
9. The preparation method according to claim 2, wherein: The method further includes step seven, aging the packaged gas sensor. Specifically, the packaged gas sensor is placed on an aging table and the temperature is set to 60° C. until the resistance of the gas sensor reaches a stable value.
10. The preparation method according to claim 9, characterized in that: The method also includes step eight, connecting the gas sensor of step seven to the measurement circuit, and placing the gas sensor in a test chamber, maintaining the chamber at room temperature, injecting 5-100ppm of DMC gas into the chamber, observing whether the resistance value of the gas sensor changes, then clearing the DMC gas in the chamber, and continuously injecting clean air, and observing again whether the resistance value of the gas sensor recovers. After repeating the test 5-6 times, if the gas sensor has a change in resistance, it indicates that the repeatability response performance of the gas sensor has passed.