Method and system for detecting thermal runaway characteristic gas of multi-component energy storage device

Abstract

The invention relates to the technical field of gas detection, in particular to a method and a system for detecting thermal runaway characteristic gas of a multi-component energy storage device. The system comprises an optical fiber excitation module, an optical signal detection module and an optical fiber gas sensing component arranged in the multi-component energy storage device, the optical fiber gas sensing component comprises a micro-nano optical fiber sensing component; the optical signal detection module is connected with the optical fiber gas sensing component to form an optical signal loop; and the optical fiber excitation module is connected with the optical signal detection module. According to the multi-component energy storage device, the detection cost caused by gas detection depending on a gas chromatography-mass spectrometer in the prior art is reduced, and accurate detection of the concentration of the to-be-detected gas can be realized under the condition that components of the to-be-detected gas in the multi-component energy storage device are not changed.

Description

Technical Field

[0001] The present application relates to the field of gas detection technology, and in particular to a method and system for detecting thermal runaway characteristic gases of a multi-component energy storage device. Background Art

[0002] In recent years, fire safety accidents caused by thermal runaway of lithium-ion battery-based energy storage devices have greatly hindered their large-scale application in the electric vehicle and energy storage sectors. Currently, energy storage device status monitoring and thermal runaway warning systems are mainly based on real-time monitoring of signals such as current, internal resistance, internal temperature, and pressure to achieve early warning. Because real-time monitoring of signals such as current, internal resistance, internal temperature, and pressure has a certain delay, it is proposed to use gas as a detection signal for analysis. Gas has the characteristic of rapid diffusion. Once a leak occurs, it will quickly spread to the surrounding area. Therefore, gas sensing can often produce a significant response signal to thermal runaway behavior earlier. Real-time and rapid detection and analysis of these characteristic gases (such as methane CH4, ethylene C2H6, and ethane C2H4) can achieve accurate monitoring and early warning of thermal runaway, thereby improving the safety and reliability of energy storage systems.

[0003] Currently, multi-component gas analysis for the detection of characteristic gases primarily relies on gas chromatography-mass spectrometry. However, these instruments are bulky, complex to operate, and expensive to use and maintain. They typically require the use of sealed tanks or sampling bags to collect gases released from energy storage devices and bring them back to the laboratory for analysis. This method not only changes the composition of the gases within, but also makes it difficult to accurately analyze thermal runaway gases in real time. Furthermore, offline detection methods cannot track the dynamic changes in the health status of energy storage devices in real time. Summary of the Invention

[0004] The present application provides a method and system for detecting thermal runaway characteristic gases in a multi-component energy storage device to solve one or more technical problems existing in the prior art and at least provide a beneficial option or create conditions.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0006] According to one aspect of an embodiment of the present application, a system for detecting thermal runaway characteristic gases in a multi-component energy storage device is provided, the system comprising an optical fiber excitation module, an optical signal detection module, and an optical fiber gas sensing component disposed within the multi-component energy storage device;

[0007] The optical fiber gas sensing component includes a micro-nano optical fiber sensing component, and the micro-nano optical fiber sensing component is used to contact a plurality of gases to be measured inside the multi-component energy storage device;

[0008] The optical signal detection module is connected to the optical fiber gas sensing component to form an optical signal loop;

[0009] The optical fiber excitation module is connected to the optical signal detection module;

[0010] The optical signal detection module generates a first optical signal for circulating clockwise within the optical signal loop and a second optical signal for circulating counterclockwise within the optical signal loop; the optical fiber excitation module generates a third optical signal and inputs the third optical signal into the optical signal loop; the first optical signal and the second optical signal are circulated in a clockwise / counterclockwise direction within the optical signal loop and pass through the micro-nano optical fiber sensing component multiple times to form a multi-beam interference optical fiber ring resonator;

[0011] After the first optical signal and the second optical signal are cyclically transmitted for a preset number of times, interference occurs, and the optical signal detection module outputs a target optical signal after interference, so as to convert the target optical signal into an electrical signal and analyze the concentration of each of the gases to be measured based on the electrical signal, so as to provide an early warning of a thermal runaway state of the multi-component energy storage device.

[0012] In one embodiment of the present application, based on the aforementioned solution, the optical fiber gas sensing component further includes a first ceramic sleeve and a second ceramic sleeve. The micro-nano optical fiber sensing component is encapsulated in the first ceramic sleeve to isolate the micro-nano optical fiber sensing component from the electrolyte generated inside the multi-component energy storage device. The second ceramic sleeve is disposed at one end of the first ceramic sleeve and is connected to the optical signal detection module.

[0013] Wherein, a microporous film is provided on the end face of the first ceramic sleeve, so that the gas to be measured inside the multi-component energy storage device enters through the microporous film and contacts the micro-nano optical fiber sensing component.

[0014] In one embodiment of the present application, based on the aforementioned solution, the optical signal detection module includes a first filter, a first reflector, a wavelength division multiplexer, a second reflector, a second filter, and a delay optical fiber; the first filter, the first reflector, the optical fiber gas sensing component, the wavelength division multiplexer, the second reflector, the second filter, and the delay optical fiber are connected in sequence in a clockwise direction to form the optical signal loop.

[0015] In one embodiment of the present application, based on the aforementioned solution, the optical signal detection module further includes a fiber coupler and a broadband light source, wherein the broadband light source is used to generate broadband laser light, and the broadband laser light is split into the first optical signal and the second optical signal after passing through the fiber coupler;

[0016] The first optical signal passes through the first filter, the first reflector, the optical fiber gas sensing component, the wavelength division multiplexer, the second reflector, the second filter and the delay optical fiber in sequence;

[0017] The second optical signal passes through the delay optical fiber, the second filter, the second reflector, the wavelength division multiplexer, the optical fiber gas sensing component, the first reflector and the first filter in sequence.

[0018] In one embodiment of the present application, based on the aforementioned solution, the first optical signal generates a first component and a second component when reaching the second reflector. The first component sequentially passes through the second reflector, the second filter, and the delay fiber to reach the fiber coupler. The second component is reflected by the second reflector and, after passing through the wavelength division multiplexer, reaches the fiber-optic gas sensing component. It is then reflected again by the first reflector, causing the second component to circulate within the fiber-optic gas sensing component.

[0019] When the second optical signal reaches the first reflector, it generates a third component and a fourth component. The third component passes through the first filter and reaches the fiber coupler. The fourth component is reflected by the first reflector and sequentially enters the fiber optic gas sensing component. It is then reflected again by the second reflector, causing the fourth component to circulate within the fiber optic gas sensing component.

[0020] In one embodiment of the present application, based on the aforementioned solution, the optical signal detection module further includes a photodetector, a lock-in amplifier, and an acquisition card. The photodetector is connected to the fiber coupler and the lock-in amplifier, and the lock-in amplifier is connected to the fiber excitation module and the acquisition card. The fiber coupler includes a plurality of ports, and the phase difference between any two of the ports is a preset phase difference.

[0021] The target optical signal is converted into a plurality of optical signals with phase differences through different ports, and the plurality of optical signals are input into the photodetector to obtain a plurality of electrical signals corresponding to the plurality of optical signals;

[0022] The output signal of the photoelectric detector is obtained after the multiple electrical signals are superimposed, and the output signal is input to the lock-in amplifier and the acquisition card to perform characteristic concentration analysis of each gas to be measured based on the output signal.

[0023] In one embodiment of the present application, based on the aforementioned scheme, the fiber excitation module includes a first pump light source, a second pump light source, a third pump light source and a coupler, wherein the first pump light source is used to output a pump laser with a wavelength of 1650.9 nm, the second pump light source is used to output a pump laser with a wavelength of 1680.2 nm, and the third pump light source is used to output a pump laser with a wavelength of 1626.5 nm; the coupler is used to couple the pump laser with a wavelength of 1650.9 nm, the pump laser with a wavelength of 1680.2 nm, and the pump laser with a wavelength of 1626.5 nm to obtain the third optical signal.

[0024] According to one aspect of an embodiment of the present application, a method for detecting characteristic gases of a multi-component energy storage device undergoing thermal runaway is provided, which is applied to the multi-component energy storage device thermal runaway characteristic gas detection system described in the above embodiment. The method comprises:

[0025] receiving an output signal acquired by the acquisition card, wherein the output signal is acquired by the photoelectric detector by detecting a target light signal, wherein the target light signal is a light signal after interference;

[0026] The characteristic concentration of each gas to be measured in the multi-component energy storage device is analyzed according to the output signal.

[0027] The beneficial effects of the present application are as follows: the optical signal detection module generates a first optical signal that circulates clockwise within the optical signal loop and a second optical signal that circulates counterclockwise within the optical signal loop. That is, the first optical signal and the second optical signal are circulated within the optical signal loop, and when passing through the micro-nano optical fiber sensing component, a multi-beam interference ring resonant cavity is formed, so that each optical signal passes through the micro-nano optical fiber sensing component multiple times within the resonant cavity to form a phase accumulation, and obtains a target optical signal, and then the target optical signal is photoelectrically converted, that is, converted into an electrical signal, and the concentration of each gas to be measured is analyzed by the electrical signal to achieve an accurate early warning of the thermal runaway state of the multi-component energy storage device. The third optical signal generated by the optical fiber excitation module is used to excite the micro-nano optical fiber sensing component within the optical signal loop.

[0028] This application innovatively designs the system structure of the optical fiber excitation module, the optical signal detection module, and the optical fiber gas sensing component, reducing the detection cost brought about by the existing technology that relies on gas chromatography-mass spectrometry for gas detection, while achieving accurate detection of the concentration of the gas to be measured without changing the components of the gas to be measured inside the multi-component energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described are only part of the embodiments of this application, not all of them. Those skilled in the art can also derive other design solutions and drawings based on these drawings without inventive effort.

[0030] Figure 1 1 is an overall block diagram of a thermal runaway characteristic gas detection system for a multi-component energy storage device according to an embodiment of the present application;

[0031] Figure 2 Schematic diagram of a multi-beam interference fiber ring resonator according to an embodiment of the present application;

[0032] Figure 3 Detailed structural diagram of a thermal runaway characteristic gas detection system for a multi-component energy storage device according to an embodiment of the present application;

[0033] Figure 4 is a graph showing theoretical normalized response curves of photodetector outputs at different reflectivities according to an embodiment of the present application;

[0034] Figure 5 This is a measurement diagram of multi-component methane CH4, ethylene C2H6, and ethane C2H4 according to an embodiment of the present application;

[0035] Figure 6 Flowchart of a method for detecting characteristic gases of a multi-component energy storage device undergoing thermal runaway according to an embodiment of the present application.

[0036] Reference numerals

[0037] Fiber excitation module 100, first pump light source 101, second pump light source 102, third pump light source 103, coupler 104, optical signal detection module 200, first filter 201, first reflector 202, wavelength division multiplexer 203, second reflector 204, second filter 205, delay fiber 206, fiber coupler 207, broadband light source 208, photodetector 209, lock-in amplifier 210, acquisition card 211, fiber gas sensor component 300, micro-nano fiber sensor component 301, first ceramic sleeve 302, second ceramic sleeve 303, third ceramic sleeve 304, energy storage device 400, multi-beam interference fiber resonant cavity 500, single-mode fiber 600. DETAILED DESCRIPTION

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0039] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0040] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or micro-controller node devices.

[0041] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0042] It should be noted that the term "plurality" used in this document refers to two or more. "And / or" describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. The character " / " generally indicates an "or" relationship between the associated objects.

[0043] The following is a detailed introduction to the thermal runaway characteristic gas detection system for a multi-component energy storage device proposed in the embodiments of the present application:

[0044] like Figure 1 、 Figure 2 and Figure 3 As shown, Figure 1 This is the overall framework diagram of the thermal runaway characteristic gas detection system for the multi-component energy storage device proposed in this application. Figure 2 This is a detailed structural diagram of the multi-beam interferometer ring resonator proposed in this application. Figure 3 This is a detailed structural diagram of the thermal runaway characteristic gas detection system for a multi-component energy storage device.

[0045] According to one aspect of the embodiment of the present application, a thermal runaway characteristic gas detection system for a multi-component energy storage device is provided, wherein the system comprises an optical fiber excitation module 100, an optical signal detection module 200, and a multi-component energy storage device (i.e. Figure 1 and Figure 3 The fiber optic gas sensing component 300 inside the energy storage device (multi-component energy storage device 400) shown;

[0046] The optical fiber gas sensing component 300 includes a micro-nano optical fiber sensing component 301, and the micro-nano optical fiber sensing component 301 is used to contact the multiple gases to be measured inside the multi-component energy storage device 400;

[0047] The optical signal detection module 200 is connected to the optical fiber gas sensing component 300 to form an optical signal loop;

[0048] The optical fiber excitation module 100 is connected to the optical signal detection module 200;

[0049] The optical signal detection module 200 generates a first optical signal for circulating clockwise within the optical signal loop and a second optical signal for circulating counterclockwise within the optical signal loop; the optical fiber excitation module 100 generates a third optical signal and inputs the third optical signal into the optical signal loop; the first optical signal and the second optical signal are circulated in a clockwise / counterclockwise direction within the optical signal loop and pass through the micro-nano optical fiber sensing component 301 multiple times to form a multi-beam interference optical fiber ring resonator 500;

[0050] After the first optical signal and the second optical signal have been transmitted in a preset number of cycles, interference occurs, and the optical signal detection module 200 outputs the target optical signal after interference, converts the target optical signal into an electrical signal, and analyzes the concentration of each gas to be tested based on the electrical signal, so as to give an early warning of the thermal runaway state of the multi-component energy storage device 400. It should be noted that the multi-component energy storage device is Figure 1 and Figure 3 Energy storage device 400 is shown.

[0051] Specifically, using Figure 3The illustrated system for detecting gases characteristic of thermal runaway in a multi-component energy storage device performs joint detection of gases characteristic of thermal runaway in a multi-component energy storage device, such as methane (CH4), ethylene (C2H6), and ethane (C2H4). The first, second, and third pump light sources 101, 102, and 103 each output three sets of periodically modulated pump lasers with wavelengths of 1650.9 nm, 1680.2 nm, and 1626.5 nm, respectively, and modulation frequencies of 20 kHz, 21 kHz, and 19 kHz, respectively.

[0052] Three groups of pump lasers are input to the fiber optic gas sensing component 300 through the coupler 104 and the wavelength division multiplexer 203. The corresponding methane CH4, ethylene C2H6, and ethane C2H4 gases are present outside the fiber optic gas sensing component 300. At the same time, the broadband light source 208 outputs a broadband detection light with a central wavelength of 1550 nanometers (i.e., the broadband laser described in this application), with a wavelength range from 1530 nanometers to 1580 nanometers. Multiple beams of pump lasers with different wavelengths and the broadband laser are connected through the fiber optic coupler (i.e., Figure 3 The first and second optical signals converted by the optical fiber coupler 207 shown are injected into the optical fiber gas sensing component 300. When the multi-component gas (i.e., the various gases to be measured described in the present application) interacts with the pump laser of a specific wavelength, some of the energy is absorbed, and the gas molecules of the gas to be measured are excited to a higher energy state. The subsequent molecular relaxation will result in local heat release and cause changes in the waveguide properties of the optical fiber core (comprehensively reflected as a change in the effective refractive index), thereby causing a cumulative phase change in another beam of detection laser light (i.e., the target optical signal) transmitted in the optical fiber (the connections between the various components in the optical signal loop of the present application are all made through single-mode optical fiber 600) away from the gas absorption line.

[0053] The broadband light source 208 is combined with the fiber coupler 207 and the multi-beam interference fiber resonator 500 to form a Sagnac demodulation system. The phase difference between any two output ends of the fiber coupler 207 (the fiber coupler 207 includes ports 1-6) is constant at 2π / 3. The balanced detection method can achieve linear demodulation between the output signal and the photothermal phase modulation. The clockwise laser (i.e., the first optical signal) and the counterclockwise laser (i.e., the second optical signal) output by the multi-beam interference fiber ring resonator 500 return to the fiber coupler 207 through the first and second reflectors respectively (i.e., the preset rounds of cyclic transmission described in this application are performed. The preset rounds can be customized according to actual conditions and are not limited here). They meet and form interference, and are input to the photodetector for detection through ports 2 and 3 of the fiber coupler 207, and finally enter the data acquisition and processing module (composed of the photodetector 209, the phase-locked amplifier 210, and the acquisition card 211). The third optical signal generated by the fiber excitation module 100 is used to excite the single-mode optical fiber 600 in the optical signal loop.

[0054] The broadband light source 208 is used as the detection laser, and the clockwise and counterclockwise detection light are used to make the optical path of the two paths of the multi-beam interference fiber ring resonator 500 completely match, and the automatic locking of the working point can be achieved without any feedback control. The theoretical response curve of the photodetector is shown in Figure 4 As shown, because the phase difference is proportional to the gas absorption intensity, when there is no gas absorption at the micro-nano fiber optic sensing component, the output of the response curve will always self-align at zero, allowing for linear signal recovery. This locks the output to zero without the need for additional feedback loops or complex modulation and demodulation techniques. Demodulation using this Sagnac demodulation system records three sets of second-order signals at different modulation frequencies, thereby obtaining the signal changes caused by gas absorption and, therefore, gas concentration information.

[0055] See Figure 5 , Figure 5 The measurement diagram of multi-component methane CH4, ethylene C2H6, and ethane C2H4 is shown. Figure 5 It can be observed that the peak-to-peak values ​​of the second-order signals measured by the absorption of methane, ethylene and ethane are 6.49mV, 12.6mV and 2.92mV respectively.

[0056] Specifically, the detection system of the above embodiment has the following advantages:

[0057] 1. Compared with a free-space optical resonator, the multi-beam interferometric fiber ring resonator 500 of this system does not require complex alignment devices and has the advantages of small size, light weight, compatibility with fiber optic systems, and remote monitoring capabilities, making it very suitable for monitoring inside energy storage devices.

[0058] 2. A low-coherence light source (i.e., broadband light source 208) is used in combination with a fiber coupler 207 to achieve high-resolution spectral demodulation and reduce the impact of parasitic noise, thereby improving the sensor's ability to resist environmental interference and essentially solving the stability problem of the multi-beam interference fiber ring resonator.

[0059] 3. Combined with photothermal spectroscopy technology, a single optical fiber can be used to complete the joint detection of multi-component gases, such as methane CH4, ethylene C2H6, and ethane C2H4, which can overcome the difficulty in identifying the components and concentrations in a mixture of multiple thermal runaway characteristic gases.

[0060] 4. By analyzing the types and concentrations of gases, the system deepens its understanding of the internal chemical and physical reaction mechanisms of the energy storage device under different states (including different working lives and different charge and discharge times), thereby accurately evaluating the operating status of the energy storage device 400 and predicting various situations that may arise in the future.

[0061] In one embodiment of the present application, the optical fiber gas sensing component 300 further includes a first ceramic sleeve 302 and a second ceramic sleeve 303. The micro-nano optical fiber sensing component 301 is encapsulated in the first ceramic sleeve 302 to isolate the micro-nano optical fiber sensing component 301 from the electrolyte generated inside the multi-component energy storage device 400. The second ceramic sleeve 303 is disposed at one end of the first ceramic sleeve 302 and both are connected to the optical signal detection module 200.

[0062] The end surface of the first ceramic sleeve 302 is provided with a microporous film, so that the gas to be measured inside the multi-component energy storage device 400 enters through the microporous film and contacts the micro-nano optical fiber sensing component 301 .

[0063] Specifically, if Figure 2 As shown, the first ceramic sleeve 302 primarily isolates the electrolyte produced by the energy storage device 400 (multi-component energy storage device), allowing the gas to be measured inside the energy storage device 400 to pass through the microporous film into the fiber optic gas sensing component 300 and contact the micro-nano fiber optic sensing component 301. The diameter of the micro-nano fiber is no greater than 10 μm, and its connection loss is less than 0.15 dB. The fiber optic gas sensing component 300 is passed through the small holes at both ends of the positive and negative electrodes of the energy storage device 400, and the small holes at both ends are sealed with epoxy resin to prevent electrolyte leakage and cured for 24 hours.

[0064] The multi-beam interference fiber resonant cavity 500 is composed of a first reflector 202, a fiber optic gas sensing component 300, a wavelength division multiplexer 203 and a second reflector 204;

[0065] The first reflector 202 is a high reflectivity dielectric film coated on the end face of the single-mode optical fiber 600;

[0066] The reflectivity of the high reflectivity dielectric film is not less than 98%;

[0067] The first reflector 202 is aligned and connected to the input end of the optical fiber gas sensing component 300 through the second ceramic sleeve 303;

[0068] The distance between the first reflector 202 and the input end of the optical fiber gas sensing component 300 is greater than 0 and less than 0.1 micrometers.

[0069] The second reflector 204 in the multi-beam interference fiber resonant cavity 500 is a high reflectivity dielectric film coated on the end face of the single-mode optical fiber 600;

[0070] The reflectivity of the high reflectivity dielectric film is not less than 98%;

[0071] The output end of the wavelength division multiplexer 203 is aligned and connected with the second reflector 204 through the third ceramic sleeve 304;

[0072] The distance between the output end of the wavelength division multiplexer 203 and the second reflector 204 is greater than 0 and less than 0.1 micrometers.

[0073] The output end of the fiber optic gas sensor component 300 is connected to the input end of the wavelength division multiplexer 203. The wavelength division multiplexer 203 is used to combine a series of pump lasers carrying information but with different wavelengths into one beam through the coupler 104, and transmit it along the single-mode optical fiber 600 to the micro-nano fiber optic sensor component 301.

[0074] The optical signal detection module 200 further includes a fiber coupler 207 and a broadband light source 208. The broadband light source 208 is used to generate broadband laser light. After passing through the fiber coupler 207, the broadband laser light is split into the first optical signal and the second optical signal.

[0075] The first optical signal passes through the first filter 201, the first reflector 202, the optical fiber gas sensing component 300, the wavelength division multiplexer 203, the second reflector 204, the second filter 205 and the delay optical fiber 206 in sequence;

[0076] The second optical signal passes through the delay optical fiber 206 , the second filter 205 , the second reflector 204 , the wavelength division multiplexer 203 , the optical fiber gas sensing component 300 , the first reflector 202 and the first filter 201 in sequence.

[0077] A portion (i.e., the first component) of the clockwise laser light (the first optical signal) is emitted through the second reflector 204, sequentially enters the second filter 205 and the delay optical fiber 206, and reaches the optical fiber coupler 207; another portion (i.e., the second component) of the clockwise laser light is reflected back into the multi-beam interference optical fiber ring resonator 500 through the second reflector 202, and forms a cyclic transmission process between the first reflector 202 and the second reflector 204.

[0078] A portion (the third component) of the counterclockwise laser light (the second optical signal) is emitted through the first reflector 202, enters the first filter 201 in sequence, and reaches the optical fiber coupler 207; another portion (the fourth component) of the counterclockwise laser light is reflected back into the multi-beam interference optical fiber ring resonator 500 through the first reflector 202, and forms a cyclic transmission process between the first reflector 202 and the second reflector 204. A resonant cavity is formed between the two high-reflectivity reflectors, so that part of the clockwise optical signal and the counterclockwise optical signal will be reflected back and forth in the resonant cavity, enhancing the phase accumulation change of the detection light.

[0079] Since there is a phase difference between any two ports 1-6 of the optical fiber coupler 207, that is, there is a phase difference between each clockwise laser (first optical signal) and the counterclockwise laser (second optical signal), they pass through the optical fiber gas sensing component 300 (i.e., the micro-nano optical fiber sensing component 301) multiple times. During the circulation process, there are multiple groups of clockwise lasers and counterclockwise lasers, and interference occurs in the optical fiber coupler 207. Finally, after superposition in the photoelectric detector 209, an output signal is obtained and input into the phase-locked amplifier 210, thereby obtaining concentration information of multiple groups of different gases.

[0080] A broadband light source 208 is used as the system's probe light, and a Sagnac demodulator is constructed in conjunction with a 3×3 coupler. The phase difference between any two output ports of the 3×3 coupler (i.e., fiber coupler 207) is constant at 2π / 3. Using balanced detection, a linear relationship between the output signal and photothermal phase modulation can be achieved. Specifically, the clockwise and counterclockwise optical signals output by the multi-beam interference fiber ring resonator 500 are respectively input to ports 4 and 6 of the 3×3 coupler (i.e., fiber coupler 207), where they meet and interfere. After interference occurs at fiber coupler 207, the signals are split through ports 2 and 3 and enter photodetector 209, resulting in an optical signal with a phase difference.

[0081] The fiber excitation module 100 includes a first pump light source 101, a second pump light source 102, a third pump light source 103 and a coupler 104;

[0082] The fiber excitation module 100 is used to generate three sets of periodically modulated pump lasers; the central wavelengths of the pump lasers are set at the near-infrared absorption spectrum wavelengths corresponding to three energy storage device thermal runaway characteristic gases (methane CH4, ethylene C2H6, and ethane C2H4), namely 1650.9 nanometers, 1680.2 nanometers, and 1626.5 nanometers; at the same time, the frequency range of the periodic modulation of the three sets of pump lasers is within 1 to 100 kHz, and the modulation frequency interval of the three sets of pump lasers is not less than 0.5 kHz.

[0083] The frequency interval of not less than 0.5 kHz is to avoid direct crosstalk between several groups of signals.

[0084] The lock-in amplifier 210 has three ports that can output electrical signals of different modulation frequencies, which respectively correspond to the electrical modulation input ends of the three pump light sources, thereby realizing frequency division multiplexing and measuring the concentrations of multiple gases.

[0085] According to one aspect of an embodiment of the present application, a method for detecting characteristic gases of a multi-component energy storage device undergoing thermal runaway is provided, which is applied to the system for detecting characteristic gases of a multi-component energy storage device undergoing thermal runaway as described in the above embodiment. Figure 6This is a flow chart of a method for detecting characteristic gases of a multi-component energy storage device in accordance with an embodiment of the present application. The method includes at least steps S1 to S2, which are described in detail as follows:

[0086] In step S1 , an output signal acquired by an acquisition card is received. The output signal is acquired by the photoelectric detector by detecting a target light signal. The target light signal is a light signal after interference.

[0087] Specifically, the acquisition card can collect the output signal in the phase-locked amplifier and then analyze the output signal, where the output signal is obtained by superimposing multiple electrical signals, and the multiple electrical signals are obtained by splitting the target optical signal by the optical fiber coupler to form multiple optical signals with phase differences.

[0088] In step S2, characteristic concentration analysis is performed on each gas to be tested in the multi-component energy storage device according to the output signal.

[0089] Specifically, because the phase difference is proportional to the intensity of gas absorption, when there is no gas absorption at the micro-nano fiber optic sensing component, the output of the response curve will always self-align at zero, allowing for linear signal recovery. This eliminates the need for additional feedback loops and complex modulation and demodulation techniques to lock the output to zero. Demodulation using the Sagnac demodulation system records three sets of second-order signals at different modulation frequencies, thereby obtaining the signal changes caused by gas absorption and the concentration of the gas being measured.

[0090] To summarize, the present application is based on a stably integrated integrated fiber resonant cavity sensing component (i.e., a multi-beam interference fiber ring resonant cavity formed by an optical signal detection module and an optical fiber gas sensing component), and at the same time adjusts and reconstructs the demodulation system in the optical signal detection module (i.e., the aforementioned Sagnac demodulation system), and uses a low-coherence light source (broadband light source) combined with an optical fiber coupler to achieve high-resolution spectral demodulation, thereby improving the ability of each sensing component to resist environmental interference.

[0091] The fiber-optic gas sensing component detects the multi-component characteristic gases generated within the multi-component energy storage device, such as the combined detection of methane (CH4), ethylene (C2H6), and ethane (C2H4), enabling a single sensing unit to accurately identify and quantitatively analyze multiple thermal runaway gases. This application proposes a novel sensing solution that combines a new structure with a new method to obtain in-situ information within the energy storage device under different states and lifespans (referring to direct detection and analysis of gas molecules under real-world conditions, without the need for sampling preprocessing, and capable of reflecting changes in gas composition in real time), accurately assess its operating status, and achieve the identification of thermal runaway gases and early warning of thermal runaway in multi-component energy storage devices.

[0092] Furthermore, the above figures are merely illustrative of the processes included in the methods according to exemplary embodiments of the present application and are not intended to be limiting. It is readily understood that the processes illustrated in the above figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes can be executed synchronously or asynchronously across multiple modules.

[0093] It should be understood that the present application is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes can be performed without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A thermal runaway characteristic gas detection system for a multi-component energy storage device, characterized in that: The system includes an optical fiber excitation module, an optical signal detection module, and an optical fiber gas sensing component arranged inside the multi-component energy storage device; The optical fiber gas sensing component includes a micro-nano optical fiber sensing component, and the micro-nano optical fiber sensing component is used to contact a plurality of gases to be measured inside the multi-component energy storage device; The optical signal detection module is connected to the optical fiber gas sensing component to form an optical signal loop; The optical fiber excitation module is connected to the optical signal detection module; The optical signal detection module generates a first optical signal for circulating clockwise within the optical signal loop and a second optical signal for circulating counterclockwise within the optical signal loop; the optical fiber excitation module generates a third optical signal and inputs the third optical signal into the optical signal loop; the first optical signal and the second optical signal are circulated in a clockwise / counterclockwise direction within the optical signal loop and pass through the micro-nano optical fiber sensing component multiple times to form a multi-beam interference optical fiber ring resonator; After the first optical signal and the second optical signal are cyclically transmitted for a preset number of times, interference occurs, and the optical signal detection module outputs a target optical signal after interference, so as to convert the target optical signal into an electrical signal and analyze the concentration of each of the gases to be measured based on the electrical signal, so as to provide an early warning of a thermal runaway state of the multi-component energy storage device.

2. The thermal runaway characteristic gas detection system for a multi-component energy storage device according to claim 1, characterized in that: The optical fiber gas sensing component further includes a first ceramic sleeve and a second ceramic sleeve. The micro-nano optical fiber sensing component is encapsulated in the first ceramic sleeve to isolate the micro-nano optical fiber sensing component from the electrolyte generated inside the multi-component energy storage device. The second ceramic sleeve is disposed at one end of the first ceramic sleeve and is connected to the optical signal detection module. Wherein, a microporous film is provided on the end face of the first ceramic sleeve, so that the gas to be measured inside the multi-component energy storage device enters through the microporous film and contacts the micro-nano optical fiber sensing component.

3. The thermal runaway characteristic gas detection system for a multi-component energy storage device according to claim 1, characterized in that: The optical signal detection module includes a first filter, a first reflector, a wavelength division multiplexer, a second reflector, a second filter and a delay optical fiber; the first filter, the first reflector, the optical fiber gas sensing component, the wavelength division multiplexer, the second reflector, the second filter and the delay optical fiber are connected in sequence in a clockwise direction to form the optical signal loop.

4. The thermal runaway characteristic gas detection system for a multi-component energy storage device according to claim 3, characterized in that: The optical signal detection module further includes an optical fiber coupler and a broadband light source, wherein the broadband light source is used to generate broadband laser light, and the broadband laser light is split into the first optical signal and the second optical signal after passing through the optical fiber coupler; The first optical signal passes through the first filter, the first reflector, the optical fiber gas sensing component, the wavelength division multiplexer, the second reflector, the second filter and the delay optical fiber in sequence; The second optical signal passes through the delay optical fiber, the second filter, the second reflector, the wavelength division multiplexer, the optical fiber gas sensing component, the first reflector and the first filter in sequence.

5. The thermal runaway characteristic gas detection system for a multi-component energy storage device according to claim 4, characterized in that: The first optical signal generates a first component and a second component when reaching the second reflector. The first component sequentially passes through the second reflector, the second filter, and the delay optical fiber to reach the optical fiber coupler. The second component is reflected by the second reflector and, after passing through the wavelength division multiplexer, reaches the optical fiber gas sensing component. It is then reflected again by the first reflector, causing the second component to circulate within the optical fiber gas sensing component. When the second optical signal reaches the first reflector, it generates a third component and a fourth component. The third component passes through the first filter and reaches the fiber coupler. The fourth component is reflected by the first reflector and sequentially enters the fiber optic gas sensing component. It is then reflected again by the second reflector, causing the fourth component to circulate within the fiber optic gas sensing component.

6. The thermal runaway characteristic gas detection system for a multi-component energy storage device according to claim 5, characterized in that: The optical signal detection module further includes a photodetector, a lock-in amplifier, and an acquisition card. The photodetector is connected to the fiber coupler and the lock-in amplifier, and the lock-in amplifier is connected to the fiber excitation module and the acquisition card. The fiber coupler includes a plurality of ports, and the phase difference between any two of the ports is a preset phase difference. The target optical signal is converted into a plurality of optical signals with phase differences through different ports, and the plurality of optical signals are input into the photodetector to obtain a plurality of electrical signals corresponding to the plurality of optical signals; The output signal of the photoelectric detector is obtained after the multiple electrical signals are superimposed, and the output signal is input to the lock-in amplifier and the acquisition card to perform characteristic concentration analysis of each gas to be measured based on the output signal.

7. The multi-component energy storage device thermal runaway characteristic gas detection system according to claim 3, characterized in that: The fiber excitation module includes a first pump light source, a second pump light source, a third pump light source and a coupler, wherein the first pump light source is used to output a pump laser with a wavelength of 1650.9 nm, the second pump light source is used to output a pump laser with a wavelength of 1680.2 nm, and the third pump light source is used to output a pump laser with a wavelength of 1626.5 nm; the coupler is used to couple the pump laser with a wavelength of 1650.9 nm, the pump laser with a wavelength of 1680.2 nm, and the pump laser with a wavelength of 1626.5 nm to obtain the third optical signal.

8. A method for detecting characteristic gases of thermal runaway in a multi-component energy storage device, characterized in that: The method is applied to the thermal runaway characteristic gas detection system for a multi-component energy storage device according to any one of claims 1 to 7, and the method comprises: receiving an output signal acquired by an acquisition card, wherein the output signal is acquired by the photoelectric detector by detecting a target light signal, wherein the target light signal is a light signal after interference; The characteristic concentration of each gas to be measured in the multi-component energy storage device is analyzed according to the output signal.

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