A dual-functional device combining Ga2O3 gas sensing and solar-blind ultraviolet detection for rapid early warning of thermal runaway in lithium batteries, and its fabrication and application.

Abstract

The application provides a Ga2O3 gas sensing and solar-blind ultraviolet detecting dual-function device for rapid early warning of lithium battery thermal runaway. An insulating substrate is cut to form a groove, and a metal electrode is evaporated, Ga2O3 nanowires are bridged at both ends of the groove, the parasitic resistance interference of the device is eliminated through the shadow shielding effect and passivation effect of the groove, and the dual-function device for detecting lithium battery thermal runaway is obtained. The bridged nanowires are used as a self-heating layer to generate Joule heat, the gas-sensitive response signals of the sensor under the lithium battery thermal runaway marker gas and the interference gas are collected, the molecular characteristics of the marker gas are learned by using an artificial neural network, the self-heating is omitted through the heat conduction step and the heat relaxation process is accelerated, and the ultrafast detection of the lithium battery thermal runaway marker gas is realized. The device can also be used as a solar-blind ultraviolet detector, the generation of ionized oxygen vacancies is inhibited by adjusting the bias voltage, rapid light response is realized, and double protection for rapid early warning of lithium battery thermal runaway is realized from two dimensions.

Description

Technical Field

[0001] This invention relates to the field of electronic device technology, specifically to a dual-function device for rapid early warning of thermal runaway in lithium batteries, consisting of a Ga2O3 gas sensor and a solar-blind ultraviolet detector, as well as its preparation and usage methods. Background Technology

[0002] The rapid increase in the number of new energy vehicles in the domestic market has led to frequent lithium battery combustion / explosion incidents in cars or charging stations. Lithium battery thermal runaway early warning mainly relies on monitoring changes in internal temperature and pressure; however, by this time, the battery combustion is irreversible, leaving insufficient escape time. In the earlier stages of lithium battery thermal runaway, unusual gas releases, such as hydrogen, ammonia, and methane, are significant characteristics of a failed battery. Gas detection can serve as a rapid early warning method for lithium battery thermal runaway. Considering the insufficient reliability of single-factor detection, and the fact that the flame radiation in the early stages of lithium battery combustion produces solar-blind ultraviolet radiation (200–280 nm), which is almost non-existent on the Earth's surface, has low background noise and false alarm rate, and can provide early warning of danger from another perspective. However, integrating the gas sensor and the solar-blind ultraviolet detector into the same system significantly increases power consumption and system complexity. Furthermore, in the extremely high-temperature scenarios of lithium battery thermal runaway, higher requirements are placed on the high-temperature resistance and reliability of the detection devices.

[0003] Metal-oxide-semiconductor (MOS) gas sensors hold promise for gas monitoring in lithium-ion battery thermal runaway due to their advantages such as high sensitivity, small size, low cost, and good compatibility. Methods utilizing artificial neural networks to analyze the molecular characteristics of marker gases and achieve gas identification are widely used. However, the gas-sensing response originates from the chemical adsorption of the analyte gas on the material surface and a slow redox reaction; the detection time for MOS sensors is typically around 1–5 minutes. Furthermore, the sensor requires an additional heater to reach its optimal operating temperature, but heat transfer to the material takes time, and the material undergoes relatively slow thermal relaxation after heating, sacrificing the sensor's gas detection response speed. The long detection time also limits the sensor's ability to track rapid changes in target gas concentration, which is detrimental to the rapid capture of trace gases released during lithium-ion battery thermal runaway. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings of the existing technology in the timely warning of thermal runaway of lithium batteries. This invention provides a dual-function device of Ga2O3 gas sensing and solar-blind ultraviolet detection for rapid early warning of thermal runaway of lithium batteries. The Ga2O3 semiconductor material is used for both gas sensor and solar-blind ultraviolet detector to detect the marker gas volatilized in the early stage of thermal runaway of lithium batteries and the solar-blind ultraviolet radiation generated by flame radiation, so as to achieve dual protection for rapid early warning of thermal runaway of lithium batteries from two dimensions.

[0005] This invention also provides a method for fabricating a dual-functional device for Ga2O3 gas sensing and solar-blind ultraviolet detection, comprising the following steps:

[0006] Step 1: Deposit a 1–20 μm thick passivation layer on an insulating substrate, then mechanically process the passivated substrate to form trench structures with a width and depth of 5–100 μm. After spin-coating a photoresist layer on the substrate surface, remove the photoresist area at the upper corner of the outer edge of the trench using ultraviolet light exposure and development. Deposit a 1–20 nm thick metal electrode in the processed area, ensuring that the electrode material precisely covers part of the trench sidewalls and surface area.

[0007] Step 2: Ga2O3 nanowires are grown in a furnace via chemical vapor deposition. A suitable Ga precursor is placed on one side of a quartz boat, and a trenched substrate is placed on the other side. The furnace is heated to 700–1300°C at a rate of 5–50°C / min, followed by the introduction of an Ar / O2 mixed gas at 100–5000 sccm. The high-temperature environment is maintained for a natural reaction for 0.5–5 hours. After the system cools naturally to room temperature, a Ga2O3 nanowire device is obtained. The Ga2O3 nanowires, insulating substrate, passivation layer, and metal electrodes together constitute a dual-function device for gas sensing and solar-blind ultraviolet detection.

[0008] Further improvements to the fabrication method of a dual-functional device for Ga2O3 gas sensing and solar-blind ultraviolet detection:

[0009] Preferably, the insulating substrate is any one of sapphire, silicon-based, ceramic, and glass.

[0010] Preferably, the passivation layer is any one of SiO2, Si3N4, SiF4, AlN, and SiC.

[0011] Preferably, the metal electrode is any one of Au, Ni / Au, Ti / Au, Pt, Cu, and indium tin oxide.

[0012] Preferably, the Ga precursor is any one of gallium metal, gallium nitride powder, trimethylgallium, and gallium trichloride.

[0013] This invention also provides a method for using a dual-function Ga2O3 gas sensing and solar-blind ultraviolet detection device. In the event of lithium battery thermal runaway, the device rapidly detects the danger through both gas detection and solar-blind ultraviolet detection. The Ga2O3 nanowire device, acting as a gas sensor, can identify the marker gas generated during lithium battery thermal runaway after gas training. The specific steps are as follows:

[0014] Step 1: Under an air background, the Ga2O3 nanowire device employs a self-heating mode with a power of 1–500 mW. The self-heating power of the gas sensor is controlled by adjusting the driving voltage, thereby stimulating the gas-sensitive response of the sensor. The real-time resistance curve R of the sensor under an air background is recorded. air (t);

[0015] Step 2: Under the influence of the marker gas and other interfering gases generated by the thermal runaway of the lithium battery, adjust the gas concentration to 0.01–1000 ppm, keep the self-heating power constant, and record the real-time resistance curve R of the Ga2O3 nanowire device. gas (t) conc ;

[0016] Step 3: Obtain the gas-sensitive response signal S of the Ga2O3 nanowire device under various gases. gas The calculation method is to use R air (t) and R gas (t) conc Divide the larger curve by the smaller curve;

[0017] Step 4: Normalize the gas-sensitive response curves of gases with different concentrations. nor (t)=(S gas (t)–S min ) / (S max –S min To eliminate concentration differences;

[0018] Step 5: Input the normalized response curves of different types and concentrations of gases into the artificial neural network algorithm to learn the molecular characteristics of the marker gases generated by lithium battery thermal runaway and establish an artificial neural network model for predicting the types of marker gases for lithium battery thermal runaway.

[0019] The steps involved in predicting lithium-ion battery thermal runaway using a dual-function device combining Ga2O3 gas sensing and solar-blind ultraviolet detection include:

[0020] S1. When the lithium battery is working normally, the ambient atmosphere concentration is constant, there is no volatilization of marker gases, no solar blind ultraviolet radiation, and the Ga2O3 nanowire device is in normal working condition. No abnormalities were detected in the gas sensing and ultraviolet detection functions.

[0021] S2. When a lithium battery is about to experience thermal runaway, the marker gas indicating a change in concentration evaporates into the atmosphere. The Ga2O3 nanowire device detects the generation of the marker gas through a pre-trained neural network model, thereby achieving a rapid early warning of thermal runaway in lithium batteries.

[0022] S3. When a lithium battery is about to experience thermal runaway, solar-blind ultraviolet light is generated simultaneously. A higher or lower bias voltage is applied to the two ends of the Ga2O3 nanowire device electrode to ionize or suppress the generation of oxygen vacancies. At a lower bias voltage (0.5–5V), the injection of photogenerated electrons suppresses the generation of ionized oxygen vacancies, thereby achieving a rapid photoresponse and enabling a rapid early warning of thermal runaway of the lithium battery.

[0023] Further improvements to the application of this dual-function device for Ga2O3 gas sensing and solar-blind ultraviolet detection:

[0024] Preferably, the marker gas generated by the thermal runaway of the lithium battery in step 2 is any one or more of carbon monoxide, carbon dioxide, methane, hydrogen, ammonia, sulfide gas, fluoride gas, and cyanide gas.

[0025] Preferably, the other interfering gases mentioned in step 2 are any one or more of alcohol gases, ketone gases, aldehyde gases, and benzene gases.

[0026] Preferably, the artificial neural network algorithm in step 5 is any one of the following: multilayer perceptron neural network, convolutional neural network, recurrent neural network, long short-term memory neural network, and backpropagation neural network.

[0027] The advantages of this invention compared to the prior art are as follows:

[0028] 1) The proposed dual-function device combining Ga2O3 gas sensing and solar-blind ultraviolet detection provides dual protection against lithium battery thermal runaway from two dimensions. Besides detecting unusual gases that are the first to evaporate before lithium battery thermal runaway, the solar-blind ultraviolet (200–280 nm) band generated by the flame radiation in the early stages of lithium battery combustion is almost non-existent on the Earth's surface, resulting in low background noise and false alarm rate, thus providing early warning of potential dangers from another perspective. Utilizing a single nanowire device to simultaneously achieve both gas sensing and solar-blind ultraviolet detection further leverages the advantages of oxide semiconductors—low power consumption, small size, and low cost—eliminating complex and cumbersome integration processes and enabling early warning of hazards.

[0029] 2) The Ga2O3 semiconductor used in this invention has great potential for gas sensing and solar-blind ultraviolet detection applications under extremely high temperature (approximately 500–1000°C) conditions of lithium battery thermal runaway due to its wide bandgap (4.9 eV), high melting point (approximately 1795°C), high breakdown electric field, good thermal conductivity, high electron saturation rate and radiation resistance, compared with the traditional SnO2 and ZnO semiconductors.

[0030] 3) This invention employs self-heating to accelerate the relatively slow gas-sensing response process of the sensor. Sensors typically require an additional heater to reach their optimal operating temperature, but heat transfer to the material takes time, and the material undergoes relatively slow thermal relaxation after heating, sacrificing the sensor's gas detection response speed. The self-heating method directly heats the sensing layer through input power or bias voltage, generating Joule heating without the need for additional insulating plates for heat conduction. Bridging Ga2O3 nanowires are grown connected across a trench, avoiding contact with the substrate, which reduces heat dissipation and quickly retains heat within the material. The thermal relaxation time of small-volume nanowires under self-heating can be reduced to tens of microseconds. The self-heating bridging nanowire method provides a superior platform for rapidly adjusting temperature and analyzing marker gas characteristics to make early warning judgments in a shorter time. For solar-blind ultraviolet detection, one-dimensional nanowires shorten carrier transport time, resulting in significant photoconductive gain. The large specific surface area and deep-level defects of the nanowires greatly extend the lifetime of photogenerated carriers, thereby achieving a high-sensitivity, high-quantum-efficiency, and fast-response nanowire solar-blind ultraviolet photodetector. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the fabrication process of the Ga2O3 gas sensing and solar-blind ultraviolet detection dual-function device prepared in Example 1.

[0032] Figure 2 This is a schematic diagram of Ga2O3 bridging nanowires grown in Example 1.

[0033] Figure 3 This is a schematic diagram of self-heating gas sensing test and solar-blind ultraviolet detection in Example 2.

[0034] In the figure, 1. Sapphire substrate, 2. SiO2 passivation layer, 3. Trench, 4. Au electrode, 5. Ga2O3 nanowire, 6. Quartz boat, 7. Gallium nitride powder, 8. Mask plate, 9. Sapphire substrate with trench and electrode, 10. Quartz tube, 11. Dry air, 12. Marking gas, 13. Flow meter, 14. Semiconductor parameter analyzer, 15. Gas washing bottle, 16. Ga2O3 nanowire device. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] Example 1

[0037] This embodiment provides a method for fabricating a dual-functional device for Ga2O3 gas sensing and solar-blind ultraviolet detection, specifically including the following steps:

[0038] like Figure 1 The diagram shown is a schematic of the fabrication process of the dual-function Ga2O3 gas sensing and solar-blind ultraviolet detection device of the present invention.

[0039] Step 1: A 10 μm thick SiO2 passivation layer 2 is grown on the c-plane sapphire substrate 1 using plasma-enhanced chemical vapor deposition. Trench 3 with widths of 10, 30, and 50 μm and depths of 20, 40, and 60 μm are mechanically cut on the sapphire substrate with the passivation layer. Next, a photoresist layer is applied to the substrate. The photoresist at the outer corner of the trench is exposed to ultraviolet light and removed using a developer. Then, a 5 nm thick Au electrode 4 is deposited onto the trench sidewalls and part of the surface using electron beam evaporation.

[0040] like Figure 2 The diagram shown is a schematic diagram of the preparation of Ga2O3 bridged nanowires according to the present invention.

[0041] Step 2: Ga2O3 nanowires 5 are grown in a tube furnace via chemical vapor deposition. Gallium nitride powder 7 is placed on the left side of a quartz boat 6, and the sapphire substrate 9 with trenches and electrodes prepared in Step 1 is placed on the right side of the quartz boat. A mask plate 8 with an opening is placed on the substrate surface to control the bridging growth of the Ga2O3 nanowires at both ends of the electrodes. The tube furnace is heated to 1000°C at a rate of 20°C / min, and then 1000 sccm of Ar / O2 mixed gas is introduced. After reacting naturally at high temperature for 1 hour, the furnace is allowed to cool naturally back to room temperature to obtain the Ga2O3 nanowire device. The Ga2O3 nanowires, sapphire substrate, SiO2 passivation layer, and Au electrodes together constitute a dual-function device for gas sensing and solar-blind ultraviolet detection.

[0042] Example 2

[0043] This embodiment provides a method for using a dual-function device for Ga2O3 gas sensing and solar-blind ultraviolet detection, specifically including the following steps:

[0044] like Figure 3 The diagram shown is a schematic of the self-heating gas sensing test and solar-blind ultraviolet detection of the present invention.

[0045] Step 1: Select the Ga2O3 gas sensing and solar-blind ultraviolet detection dual-function device prepared in Step 2 of Example 1, place it in the gas-sensitive test chamber, and control the flow rate of the dry air 11 to 1000 sccm through the flow meter 13. The Ga2O3 nanowire device adopts a self-heating mode, and the nanowire power is adjusted to 50mW by adjusting the driving voltage. Record the real-time resistance curve R of the sensor against the air background.air (t);

[0046] Step 2: Select hydrogen, ammonia, and methane as marker gases for lithium battery thermal runaway, with a concentration of 0.1–200 ppm. Then, select methanol and acetone at 1–200 ppm as interfering gases. Maintain the self-heating power at 50 mW and record the real-time resistance curve R of the Ga2O3 nanowire device. gas (t) conc ;

[0047] Step 3: Obtain the gas-sensitive response signal S of the Ga2O3 nanowire device under various gases. gas The calculation method is to use R air (t) and R gas (t) conc Divide the larger curve by the smaller curve;

[0048] Step 4: Normalize the gas-sensitive response curves of gases with different concentrations. nor (t)=(S gas (t)–S min ) / (S max –S min To eliminate concentration differences;

[0049] Step 5: Input the normalized response curves of different types and concentrations of gases into the convolutional neural network algorithm to learn the molecular characteristics of hydrogen, ammonia and methane, and establish an artificial neural network model for predicting the types of gases that indicate thermal runaway in lithium batteries.

[0050] Step 6: When the lithium battery is about to experience thermal runaway, the marker gas indicating the change in concentration evaporates into the atmosphere. The Ga2O3 nanowire device 16 identifies the generation of the marker gas through a pre-trained convolutional neural network model. A bias voltage of 3V is applied across the electrodes of the Ga2O3 nanowire device to detect the solar blind ultraviolet radiation generated simultaneously with the impending thermal runaway of the lithium battery. This provides dual protection for rapid early warning of thermal runaway of the lithium battery from two perspectives.

Claims

1. A dual-function device for rapid early warning of thermal runaway in lithium batteries, comprising Ga2O3 gas sensing and solar-blind ultraviolet detection, characterized in that... The device includes a trenched insulating substrate, metal electrodes, a passivation layer, and bridging Ga2O3 nanowires. The Ga2O3 semiconductor material is used in both gas sensors and solar-blind ultraviolet detectors to detect the marker gases that volatilize in the early stages of lithium battery thermal runaway and the solar-blind ultraviolet radiation generated by flame radiation, thus providing dual protection for rapid early warning of lithium battery thermal runaway from two dimensions.

2. A method for fabricating a dual-functional Ga2O3 gas sensing and solar-blind ultraviolet detection device according to claim 1, characterized in that, Includes the following steps: Step 1: Deposit a 1–20 μm thick passivation layer on an insulating substrate. Then, perform mechanical processing on the passivated substrate to form a trench structure of a specific size. The width and depth of the trench are 5–100 μm. After spin-coating a photoresist layer on the substrate surface, remove the photoresist area at the upper corner of the outer edge of the trench by ultraviolet light exposure and development process. Evaporate a 1–20 nm thick metal electrode in the processing area so that the electrode material accurately covers part of the trench sidewall and surface area. Step 2: Ga2O3 nanowires are grown in a furnace via chemical vapor deposition. A suitable Ga precursor is placed on one side of a quartz boat, and a grooved substrate is placed on the other side. The furnace is heated to 700–1300°C at a rate of 5–50°C / min, and then an Ar / O2 mixed gas of 100–5000 sccm is introduced to maintain the high-temperature environment for natural reaction for 0.5–5 hours. After the system naturally cools to room temperature, Ga2O3 nanowires are obtained. The Ga2O3 nanowires, insulating substrate, passivation layer, and metal electrode together constitute a dual-function device for gas sensing and solar-blind ultraviolet detection.

3. The method for fabricating the dual-functional Ga2O3 gas sensing and solar-blind ultraviolet detection device according to claim 2, characterized in that, The insulating substrate can be any one of sapphire, silicon, ceramic, or glass.

4. The method for fabricating a dual-functional device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 2, characterized in that, The passivation layer is any one of SiO2, Si3N4, SiF4, AlN, and SiC.

5. The method for fabricating a dual-functional device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 2, characterized in that, The metal electrode is any one of Au, Ni / Au, Ti / Au, Pt, Cu, and indium tin oxide.

6. The method for fabricating a dual-functional device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 2, characterized in that, The Ga precursor is any one of gallium metal, gallium nitride powder, trimethylgallium, and gallium trichloride.

7. A method of using the dual-function device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 1, characterized in that, When detecting thermal runaway in lithium batteries, a dual approach of gas detection and solar-blind ultraviolet detection is used to quickly detect the danger. The specific steps are as follows: Step 1: Under an air background, the Ga2O3 nanowire device employs a self-heating mode with a power of 1–500 mW. The self-heating power of the gas sensor is controlled by adjusting the driving voltage, thereby stimulating the gas-sensitive response of the sensor. The real-time resistance curve R of the sensor under an air background is recorded. air (t); Step 2: Under the influence of the marker gas and other interfering gases generated by the thermal runaway of the lithium battery, adjust the gas concentration to 0.01–1000 ppm, keep the self-heating power constant, and record the real-time resistance curve R of the Ga2O3 nanowire device. gas (t) conc ; Step 3: Obtain the gas-sensitive response signal S of the Ga2O3 nanowire device under various gases. gas The calculation method is to use R air (t) and R gas (t) conc Divide the larger curve by the smaller curve; Step 4: Normalize the gas-sensitive response curves of gases with different concentrations. nor (t)=(S gas (t)–S min ) / (S max –S min To eliminate concentration differences; Step 5: Input the normalized response curves of different types and concentrations of gases into the artificial neural network algorithm to learn the molecular characteristics of the marker gases generated by lithium battery thermal runaway and establish an artificial neural network model for predicting the types of marker gases for lithium battery thermal runaway.

8. The method of using the dual-function device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 7, characterized in that, The marking gas is any one or more of carbon monoxide, carbon dioxide, methane, hydrogen, ammonia, sulfide gas, fluoride gas, and cyanide gas, and the other interfering gases are any one or more of alcohol gas, ketone gas, aldehyde gas, and benzene gas.

9. The method of using the dual-function device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 7, characterized in that, The artificial neural network algorithm can be any one of the following: multilayer perceptron neural network, convolutional neural network, recurrent neural network, long short-term memory neural network, and backpropagation neural network.

10. The method of using the dual-function device for Ga2O3 gas sensing and solar-blind ultraviolet detection according to claim 7, characterized in that, The steps for predicting lithium battery thermal runaway using a dual-function device combining Ga2O3 gas sensing and solar-blind ultraviolet detection are as follows: S1. When the lithium battery is working normally, the ambient atmosphere concentration is constant, there is no volatilization of marker gas, no solar blind ultraviolet radiation, and the Ga2O3 nanowire device is in normal working condition. No abnormalities were detected in the gas sensing and ultraviolet detection functions. S2. When a lithium battery is about to experience thermal runaway, the marker gas indicating a change in concentration evaporates into the atmosphere. The Ga2O3 nanowire device detects the generation of the marker gas through a pre-trained neural network model, thereby achieving a rapid early warning of thermal runaway in lithium batteries. S3. When a lithium battery is about to experience thermal runaway, solar-blind ultraviolet light is generated simultaneously. A higher or lower bias voltage is applied to the two ends of the Ga2O3 nanowire device electrode to ionize or suppress the generation of oxygen vacancies. At a lower bias voltage (0.5–5V), the injection of photogenerated electrons suppresses the generation of ionized oxygen vacancies, thereby achieving a rapid photoresponse and enabling a rapid early warning of thermal runaway of the lithium battery.

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