An integrated fiber optic dual-parameter seawater metal-air battery monitoring system, its monitoring method, and its application.

Abstract

This application relates to an integrated fiber optic dual-parameter monitoring system for seawater metal-air batteries, its monitoring method, and its application, belonging to the field of battery monitoring technology. The monitoring system of this application includes a seawater metal-air battery cell, an integrated fiber optic sensing unit, and a spectral demodulation module. The seawater metal-air battery cell includes an oxygen reduction cathode, which comprises an electrode composite substrate and a catalyst layer loaded on the electrode composite substrate. The integrated fiber optic sensing unit includes a single optical fiber, on which a first fiber Bragg grating and a second fiber Bragg grating are sequentially arranged along the axial direction. The spectral demodulation module is optically connected to the optical fiber and is used to receive and analyze the wavelength signal of the reflected light. The monitoring system provided in this application utilizes a single optical fiber to achieve simultaneous monitoring and cross-sensitivity decoupling of stress and temperature dual parameters, and has advantages such as compact structure, low cost, and high measurement accuracy. It can be applied to the health status assessment and failure early warning of seawater metal-air batteries.

Description

Technical Field

[0001] This application relates to the field of battery monitoring technology, and in particular to an integrated fiber optic dual-parameter seawater metal-air battery monitoring system, its monitoring method, and its application. Background Technology

[0002] Seawater metal-air batteries utilize natural seawater as the electrolyte, achieving a direct conversion of chemical energy into electrical energy through a redox reaction between an active metal anode (such as magnesium, aluminum, or zinc) and dissolved oxygen in the seawater. This battery system boasts high energy density, a simple open structure, and long storage life, making it particularly suitable for long-term operational or emergency power supply scenarios such as underwater unmanned vehicles, marine observation platforms, and deep-sea equipment. However, in the actual operation of seawater metal-air batteries, cathode performance degradation is one of the main causes of battery failure. Specifically, the oxygen reduction reaction at the cathode generates a large amount of OH-. - Ions cause a local pH increase at the cathode, where calcium and magnesium ions in seawater react with OH-. - The precipitation of Ca(OH)₂ and Mg(OH)₂ gradually covers the active sites of the catalyst and blocks the mass transfer channels. When the precipitation accumulates to a certain extent, the battery output voltage drops sharply, and the equipment suddenly shuts down. Therefore, real-time monitoring of the degree of cathode precipitation accumulation is of great significance for early warning of battery failure and ensuring reliable operation of equipment. In addition, temperature is also a key parameter affecting the performance of seawater metal-air batteries. The marine environment temperature has significant diurnal fluctuations and seasonal variations, which directly affect the conductivity, oxygen solubility, and reaction kinetics of the seawater electrolyte; at the same time, the release of reaction heat and Joule heat during battery discharge leads to dynamic changes in the internal temperature of the battery. Temperature not only affects the output characteristics of the battery, but also changes the precipitation formation rate, thereby affecting the cathode failure process. In the existing technology, some studies have used fiber Bragg gratings (FBGs) to monitor cathode precipitation stress or battery temperature, but these schemes usually require two independent optical fibers or two independent sensing systems, which increases the system complexity and cost and is not conducive to multi-point integrated monitoring. More importantly, the wavelength shift of FBGs is affected by both stress and temperature, i.e., there is a "cross-sensitivity" problem. Attempting to monitor stress and temperature simultaneously using a single fiber optic cable (FBG) fails to distinguish whether wavelength shifts originate from precipitation stress or temperature changes, leading to measurement errors. Using two separate fibers for monitoring results in a complex and costly system. Therefore, achieving simultaneous stress and temperature monitoring on a single fiber and effectively decoupling their cross-influence has become a pressing technical challenge in this field. Summary of the Invention

[0003] In view of this, this application provides an integrated fiber optic dual-parameter seawater metal-air battery monitoring system, its monitoring method, and its application. It utilizes two fiber Bragg gratings on a single optical fiber, deployed in stress-sensitive and stress-free modes respectively, to achieve synchronous monitoring of sedimentation stress and temperature. Furthermore, it decouples cross-sensitivity through a temperature compensation algorithm, overcoming the shortcomings of complex multi-sensor schemes and large measurement errors of single-sensor cross-sensitivity in existing technologies. This provides an integrated solution for the health assessment of seawater metal-air batteries.

[0004] The first aspect of this application provides an integrated fiber optic dual-parameter seawater metal-air battery monitoring system, including a seawater metal-air battery cell, an integrated fiber optic sensing unit, and a spectral demodulation module;

[0005] The seawater metal-air battery cell includes an electrochemical reaction system using seawater as the electrolyte. The electrochemical reaction system includes at least one oxygen reduction cathode, which includes an electrode composite substrate and a catalyst layer supported on the electrode composite substrate.

[0006] The integrated fiber optic sensing unit includes a fiber optic cable, on which a first fiber Bragg grating and a second fiber Bragg grating are sequentially arranged along the axial direction. The first fiber Bragg grating is disposed on the catalyst layer surface of the oxygen reduction cathode in a stress-sensitive manner to sense the compressive stress generated by precipitation accumulation. The second fiber Bragg grating is disposed in the temperature reference region of the seawater metal-air battery cell in a stress-free encapsulation manner to sense temperature changes without being affected by precipitation compressive stress.

[0007] The spectral demodulation module is connected to the optical path of the optical fiber and is used to receive and analyze the wavelength signal of the reflected light;

[0008] In this process, the reflected wavelength of the first fiber Bragg grating is coupled and shifted with precipitation extrusion stress and temperature changes, while the reflected wavelength of the second fiber Bragg grating is shifted only with temperature changes. The spectral demodulation module detects the wavelength shift of the first and second fiber Bragg gratings, uses the temperature information measured by the second fiber Bragg grating to perform temperature compensation for the wavelength shift of the first fiber Bragg grating, and decouples to obtain the true wavelength shift caused by precipitation extrusion stress, thereby obtaining the precipitation accumulation degree of the oxygen reduction cathode and the temperature information of the seawater metal-air battery cell, respectively.

[0009] It should be noted that stress-sensitive packaging refers to the change in wavelength caused by stress on the fiber Bragg grating. Stress-free packaging refers to packaging using capillary glass tubes or suspended packaging.

[0010] Preferably, the optical fiber is arranged in a U-shape inside the catalyst layer of the oxygen reduction cathode. The temperature reference region refers to the upper part of the U-shaped arrangement of the optical fiber.

[0011] Preferably, the first fiber Bragg grating is located in the lower part of the U-shape to enhance sensitivity to precipitation extrusion stress;

[0012] The second fiber Bragg grating is located in the upper part of the U-shape and is encapsulated in a capillary glass tube or suspended encapsulation, so that it is in a free state and only responds to temperature.

[0013] Specifically, the first fiber Bragg grating is encapsulated in a stress-sensitive manner and located in the bent section of the fiber to sense precipitation extrusion stress.

[0014] Preferably, the initial center wavelength interval between the first fiber Bragg grating and the second fiber Bragg grating is greater than 3 nm, so that their reflection spectra do not interfere with each other during demodulation, thereby realizing parallel monitoring of dual parameters on a single fiber.

[0015] Preferably, the spectral demodulation module includes a spectral analyzer or a fiber Bragg grating demodulator, used to track the changes in the peak reflection wavelength of the first fiber Bragg grating and the second fiber Bragg grating in real time.

[0016] Preferably, the electrode composite substrate is prepared by hot pressing a carbon layer, nickel foam, and an air diffusion layer.

[0017] A second aspect of this application also provides an integrated fiber optic dual-parameter seawater metal-air battery monitoring method, applied to the aforementioned integrated fiber optic dual-parameter seawater metal-air battery monitoring system, comprising the following steps:

[0018] Step S1: Before the seawater metal-air battery is put into operation, calibrate the wavelength-stress correspondence and its temperature sensitivity coefficient α1 of the first fiber Bragg grating, and calibrate the wavelength-temperature correspondence of the second fiber Bragg grating.

[0019] Step S2: During the operation of the seawater metal-air battery, the reflection wavelength λ1 of the first fiber Bragg grating and the reflection wavelength λ2 of the second fiber Bragg grating are monitored in real time.

[0020] Step S3: Based on the wavelength-temperature correspondence of the second fiber Bragg grating, convert λ2 into the current temperature value T, and calculate the temperature change ΔT.

[0021] Step S4: Based on the temperature change ΔT and the temperature sensitivity coefficient α1 of the first fiber Bragg grating, perform temperature compensation on the total wavelength shift Δλ1 of the first fiber Bragg grating to obtain the net wavelength shift caused by precipitation extrusion stress: Δλ1_stress = Δλ1 - α1·ΔT;

[0022] Step S5: Based on the net wavelength offset Δλ1_stress and the wavelength-stress correspondence, calculate the degree of precipitation accumulation on the surface of the oxygen reduction cathode.

[0023] Step S6: When the degree of precipitation accumulation exceeds the preset threshold, a failure warning signal is issued.

[0024] Preferably, the method further includes step S7: establishing a temperature-precipitation correlation model based on the temperature change rate dT / dt and the precipitation accumulation rate dM / dt, used to predict precipitation formation trends or optimize battery operating conditions. The temperature change rate dT / dt = ΔT / Δt; the precipitation accumulation rate dM / dt = Δλ1_stress / Δt. Δt is the change in discharge time.

[0025] Preferably, in step S1, the wavelength-stress correspondence is established by applying precipitates of different masses to the surface of the oxygen reduction cathode, recording the wavelength offset of the corresponding first fiber Bragg grating, and fitting the stress sensitivity coefficient.

[0026] The wavelength-temperature correspondence in step S1 is established by placing the second fiber Bragg grating in a constant temperature environment, recording its reflected wavelength at different temperature points, and fitting the temperature sensitivity coefficient.

[0027] The third aspect of this application also provides the application of the aforementioned integrated fiber optic dual-parameter seawater metal-air battery monitoring system in marine equipment energy management.

[0028] Compared with the prior art, this application has the following advantages:

[0029] 1. Single-fiber dual-parameter synchronous monitoring: This application is the first to integrate two FBGs with different functions onto a single optical fiber, enabling simultaneous monitoring of cathode deposition stress and battery temperature in seawater metal-air batteries. Compared to schemes using two independent optical fibers or two sets of sensors for separate monitoring, this application saves one optical fiber and its associated demodulation channel, reducing the space occupied by internal wiring within the battery and significantly lowering system complexity and cost. Simultaneously, the two FBGs share the same optical path and spectral demodulation module, simplifying the system architecture and facilitating engineering applications and large-scale deployment.

[0030] 2. This application effectively decouples the inherent stress and temperature cross-sensitivity problem of the FBG by setting up an independent temperature sensing FBG and combining it with the compensation formula Δλ1_stress = Δλ1 - α1·ΔT.

[0031] 3. Structural Innovation - U-shaped Layout Enhances Stress Response. This application arranges the first FBG in a U-shape within the cathode catalyst layer, positioning the grating in a curved or peaked section. Compared to a straight layout, the U-shaped structure concentrates the compressive stress generated by precipitation within the grating region, resulting in higher stress-wavelength response sensitivity and facilitating early detection of precipitation formation. Simultaneously, the U-shaped layout increases the contact area between the optical fiber and the catalyst layer, improving stress transmission efficiency and ensuring the grating can promptly detect precipitation accumulation.

[0032] 4. This application designs the initial center wavelength interval of the two FBGs to be greater than 3 nm, ensuring that the two reflection spectra never overlap during the entire discharge process (including the wavelength redshift caused by temperature rise). This design guarantees that the spectral demodulation module can independently and accurately read the wavelength signals of the two gratings, realizing parallel monitoring of dual parameters on a single optical fiber.

[0033] 5. In summary, this application overcomes the shortcomings of existing technologies, such as complex multi-sensor schemes, single-sensor cross-sensitivity, and large measurement errors without temperature compensation, through multi-level innovations such as integrated fiber optic design, temperature compensation algorithm, U-shaped layout structure and dual-parameter correlation analysis. It provides a brand-new integrated solution for the health status assessment of seawater metal-air batteries. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the integrated fiber optic dual-parameter seawater metal-air battery monitoring system of this application.

[0036] Figure 2 This is a schematic diagram of the assembly of the seawater metal-air battery of this application;

[0037] Figure 3 This is a schematic diagram of the arrangement of U-shaped optical fibers in the cathode catalyst layer in the embodiments of this application;

[0038] Figure 4 This is a structural diagram of the integrated fiber optic dual-parameter seawater metal-air battery monitoring system of this application.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Seawater metal-air battery cell;

[0041] 11. Cathode location; 12. Oxygen reduction cathode; 13. Anode location;

[0042] 121. Electrode composite substrate; 122. Catalyst layer;

[0043] 1211, Carbon paper; 1212, Nickel foam; 1213, Gas diffusion layer;

[0044] 2. Optical fiber;

[0045] 21. Upper side of fiber optic FBG segment; 22. Lower side of fiber optic FBG segment;

[0046] 3. Spectral demodulation module. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0049] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared by commercial purchase or conventional methods.

[0050] like Figure 4 As shown, this application provides an integrated fiber optic dual-parameter seawater metal-air battery monitoring system. First, an integrated fiber optic sensor with two FBGs is fabricated. The first FBG is arranged in a U-shape inside the catalyst layer 122 of the oxygen reduction cathode 12 to sense precipitation compression stress. The second FBG is disposed in a stress-free encapsulation on the outer wall of the seawater metal-air battery cell 1 (which includes a cathode arrangement 11, an oxygen reduction cathode 12, and an anode arrangement 13) to sense temperature. An optical fiber 2 is connected to a spectral demodulation module 3 to monitor the reflected wavelengths of the two FBGs in real time. The wavelength shift of the first FBG is compensated by the temperature measured by the second FBG to eliminate temperature cross-interference, thereby accurately obtaining the degree of precipitation accumulation.

[0051] Specifically: The U-shaped arrangement of the first FBG aims to concentrate the compressive stress generated by precipitation in the lower section of the U-shape, thereby improving the stress-wavelength response sensitivity. The second FBG is located in the upper section of the U-shape and is unaffected by precipitation stress. That is, it corresponds to the upper side 21 and the lower side 22 of the fiber FBG segment.

[0052] The temperature compensation principle is based on the characteristic that the wavelength shift of the first FBG is simultaneously affected by stress and temperature. The total wavelength shift Δλ1 = Δλ1_stress + α1·ΔT, where Δλ1_stress is the stress contribution and α1 is the temperature sensitivity coefficient of the first FBG. By measuring ΔT using the second FBG, Δλ1_stress = Δλ1 - α1·ΔT can be calculated, thereby eliminating temperature interference.

[0053] Example 1: U-shaped deployment of integrated fiber optic dual-parameter monitoring system

[0054] I. Methods for constructing a monitoring system

[0055] i. Fabrication of integrated fiber optic sensors

[0056] Take a 100 mm long single-mode optical fiber and write two fiber Bragg gratings (FBGs) onto it:

[0057] The two FBGs are spaced 30 mm apart to ensure they do not interfere with each other during deployment.

[0058] The first FBG region is processed into a U-shape with a bending radius of 8 mm. The upper and lower parts of the U-shape are the positions of the grating.

[0059] ii. Preparation of FBG-containing cathodes

[0060] An electrode composite substrate 121 (prepared by hot pressing carbon paper 1211, nickel foam 1212, and air diffusion layer 1213 (air diffusion film)) was used as the cathode substrate (dimensions: 70 mm long × 25 mm wide, with an actual reaction area of ​​1 cm²). The specific process was as follows: First, carbon paper 1211, nickel foam 1212, and air diffusion film were stacked sequentially on top of each other and then hot-pressed for 8 minutes at 80°C. Then, a catalyst slurry (catalyst slurry: 5 mg catalyst + 980 μL tetraethyl ortho-ethyl alcohol + 20 μL Nafion membrane solution, obtained by ultrasonication for 30 min) was drop-coated onto the side with the carbon paper. 2 Weigh 5 mg of 20 wt% Pt / C oxygen reduction catalyst, add 20 μL of Nafion solution and 980 μL of anhydrous ethanol, and ultrasonically disperse for 30 min to form a homogeneous catalyst ink. Coat the catalyst ink uniformly onto the electrode composite substrate at a coating density of 1 mg / cm². 2 The prepared cathode was placed in a vacuum drying oven and dried at 60 °C to allow the ethanol in the catalyst layer to fully evaporate.

[0061] A U-shaped optical fiber is fixed to the cathode surface, with the lower FBG serving as a stress sensor. The upper part serves as a temperature sensor, and is encapsulated in a capillary glass tube for stress-free operation, ensuring that it is only affected by temperature and not by stress.

[0062] iii. Assemble seawater metal-air batteries

[0063] A magnesium plate (75 mm long × 25 mm wide × 2 mm thick) was used as the anode, and the FBG-containing electrode prepared above was used as the cathode. An acrylic sheet was used to fabricate the battery casing, resulting in an effective reaction area of ​​1 cm². 2 The distance between the cathode and anode is 8 mm. After the battery is assembled, natural seawater is injected into the casing as the electrolyte to ensure that the electrodes are completely submerged. Figure 2 This is a schematic diagram of the assembly of the seawater metal-air battery of this application; Figure 3 This is a schematic diagram of the arrangement of U-shaped optical fibers in the cathode catalyst layer in an embodiment of this application.

[0064] iv. Connect the spectral demodulation system

[0065] Connect the fiber optic cable to the OSA spectrometer via a fiber optic patch cord. Set the scanning range to 1525 nm to 1560 nm and the resolution to 0.02 nm. Simultaneously connect a computer for data acquisition and recording.

[0066] First fiber Bragg grating (stress sensing): center wavelength 1530 nm, grating length 5 mm.

[0067] Second fiber Bragg grating (temperature sensing): center wavelength 1550 nm, grating length 5 mm.

[0068] The two fiber Bragg gratings are spaced 20 mm apart to ensure that they do not interfere with each other during deployment.

[0069] II. Sensor Calibration Method

[0070] i. Temperature calibration

[0071] Before the battery is put into operation, the assembled battery is placed in a constant temperature chamber with temperature points set at 5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, and 35 ℃, and held at each temperature point for 30 min. At the same time, the temperature response of the first FBG is recorded to obtain its temperature sensitivity coefficient.

[0072] ii. Stress calibration

[0073] A known mass of precipitate (simulating a mixture of Ca(OH)2 and Mg(OH)2) was applied at different locations on the cathode surface.

[0074] III. Testing Methods for Monitoring Systems

[0075] The assembled seawater metal-air battery was placed at room temperature and subjected to constant current discharge testing using the LAND battery testing system. The test parameters were set as follows:

[0076] Discharge mode: Constant current discharge;

[0077] Discharge current density: 10 mA / cm 2 (Corresponding discharge current 10 mA);

[0078] Data acquisition interval: The voltage acquisition interval is 30 s, and the reflection wavelengths of the two FBGs are recorded simultaneously;

[0079] Discharge cut-off condition: Battery voltage drops to 0.1 V;

[0080] During the discharge process, the battery voltage and the center wavelength of the two FBGs are recorded simultaneously, and the stress wavelength shift and the degree of precipitation accumulation after temperature compensation are calculated in real time.

[0081] Figure 1 This is a schematic diagram of the integrated fiber optic dual-parameter seawater metal-air battery monitoring system of this application. The integrated fiber optic dual-parameter seawater metal-air battery monitoring method in this embodiment includes the following steps:

[0082] Step S1: Before the seawater metal-air battery is put into operation, calibrate the wavelength-stress correspondence and its temperature sensitivity coefficient α1 of the first fiber Bragg grating, and calibrate the wavelength-temperature correspondence of the second fiber Bragg grating.

[0083] Step S2: During the operation of the seawater metal-air battery, the reflection wavelength λ1 of the first fiber Bragg grating and the reflection wavelength λ2 of the second fiber Bragg grating are monitored in real time.

[0084] Step S3: Based on the wavelength-temperature correspondence of the second fiber Bragg grating, convert λ2 into the current temperature value T, and calculate the temperature change ΔT.

[0085] Step S4: Based on the temperature change ΔT and the temperature sensitivity coefficient α1 of the first fiber Bragg grating, perform temperature compensation on the total wavelength shift Δλ1 of the first fiber Bragg grating to obtain the net wavelength shift caused by precipitation extrusion stress: Δλ1_stress = Δλ1 - α1·ΔT;

[0086] Step S5: Based on the net wavelength offset Δλ1_stress and the wavelength-stress correspondence, calculate the degree of precipitation accumulation on the surface of the oxygen reduction cathode.

[0087] Step S6: When the degree of sediment accumulation exceeds the preset threshold, a failure warning signal is issued;

[0088] Step S7: Based on the temperature change rate dT / dt and the precipitation accumulation rate dM / dt, establish a temperature-precipitation correlation model to predict precipitation formation trends or optimize battery operating conditions.

[0089] Specifically, in step S1, the wavelength-stress correspondence is established by applying precipitates of different masses to the surface of the oxygen reduction cathode, recording the wavelength offset of the corresponding first fiber Bragg grating, and fitting the stress sensitivity coefficient.

[0090] The wavelength-temperature correspondence in step S1 is established by placing the second fiber Bragg grating in a constant temperature environment, recording its reflected wavelength at different temperature points, and fitting the temperature sensitivity coefficient.

[0091] Comparative Example 1: Single FBG without temperature compensation monitoring

[0092] The same cathode structure and discharge conditions as in Example 1 were used, but only one FBG was used, without an independent temperature-compensated FBG, and the deposition accumulation was directly judged based on the total wavelength shift.

[0093] Comparative Example 2: Discrete monitoring using two optical fibers

[0094] The same cathode structure as in Example 1 is used, but two independent optical fibers are used: one fixed to the lower side of the cathode for stress monitoring, and the other fixed to the upper side of the cathode for temperature monitoring.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An integrated fiber optic dual-parameter seawater metal-air battery monitoring system, characterized in that, It includes seawater metal-air battery cells, integrated fiber optic sensing units, and spectral demodulation modules; The seawater metal-air battery cell includes an electrochemical reaction system using seawater as the electrolyte. The electrochemical reaction system includes at least one oxygen reduction cathode, which includes an electrode composite substrate and a catalyst layer supported on the electrode composite substrate. The integrated fiber optic sensing unit includes a fiber optic cable, on which a first fiber Bragg grating and a second fiber Bragg grating are sequentially arranged along the axial direction. The first fiber Bragg grating is disposed on the surface of the catalyst layer of the oxygen reduction cathode in a stress-sensitive manner to sense the compressive stress generated by precipitation accumulation. The second fiber Bragg grating is disposed in the temperature reference region of the seawater metal-air battery cell in a stress-free encapsulation manner, for sensing temperature changes and unaffected by sedimentation and compression stress; The spectral demodulation module is connected to the optical path of the optical fiber and is used to receive and analyze the wavelength signal of the reflected light; In this process, the reflected wavelength of the first fiber Bragg grating is coupled and shifted with precipitation extrusion stress and temperature changes, while the reflected wavelength of the second fiber Bragg grating is shifted only with temperature changes. The spectral demodulation module detects the wavelength shift of the first and second fiber Bragg gratings, uses the temperature information measured by the second fiber Bragg grating to perform temperature compensation for the wavelength shift of the first fiber Bragg grating, and decouples to obtain the true wavelength shift caused by precipitation extrusion stress, thereby obtaining the precipitation accumulation degree of the oxygen reduction cathode and the temperature information of the seawater metal-air battery cell, respectively.

2. The integrated fiber optic dual-parameter seawater metal-air battery monitoring system according to claim 1, characterized in that, The optical fiber is arranged in a U-shape inside the catalyst layer of the oxygen reduction cathode.

3. The integrated fiber optic dual-parameter seawater metal-air battery monitoring system according to claim 1, characterized in that, The first fiber Bragg grating is located in the lower part of the U-shape; The second fiber Bragg grating is located in the upper part of the U-shape and is encapsulated in a capillary glass tube or suspended encapsulation.

4. The integrated fiber optic dual-parameter seawater metal-air battery monitoring system according to claim 1, characterized in that, The initial center wavelength interval between the first fiber Bragg grating and the second fiber Bragg grating is greater than 3 nm.

5. The integrated fiber optic dual-parameter seawater metal-air battery monitoring system according to claim 1, characterized in that, The spectral demodulation module includes a spectral analyzer or a fiber optic demodulator.

6. The integrated fiber optic dual-parameter seawater metal-air battery monitoring system according to claim 1, characterized in that, The electrode composite substrate is prepared by hot pressing a carbon layer, nickel foam, and an air diffusion layer.

7. An integrated fiber optic dual-parameter seawater metal-air battery monitoring method, characterized in that, The integrated fiber optic dual-parameter seawater metal-air battery monitoring system applied to any one of claims 1 to 6 includes the following steps: Step S1: Before the seawater metal-air battery is put into operation, calibrate the wavelength-stress correspondence and its temperature sensitivity coefficient α1 of the first fiber Bragg grating, and calibrate the wavelength-temperature correspondence of the second fiber Bragg grating. Step S2: During the operation of the seawater metal-air battery, the reflection wavelength λ1 of the first fiber Bragg grating and the reflection wavelength λ2 of the second fiber Bragg grating are monitored in real time. Step S3: Based on the wavelength-temperature correspondence of the second fiber Bragg grating, convert λ2 into the current temperature value T, and calculate the temperature change ΔT. Step S4: Based on the temperature change ΔT and the temperature sensitivity coefficient α1 of the first fiber Bragg grating, perform temperature compensation on the total wavelength shift Δλ1 of the first fiber Bragg grating to obtain the net wavelength shift caused by precipitation extrusion stress: Δλ1_stress = Δλ1 - α1·ΔT; Step S5: Based on the net wavelength offset Δλ1_stress and the wavelength-stress correspondence, calculate the degree of precipitation accumulation on the surface of the oxygen reduction cathode. Step S6: When the degree of precipitation accumulation exceeds the preset threshold, a failure warning signal is issued.

8. The integrated fiber optic dual-parameter seawater metal-air battery monitoring method according to claim 7, characterized in that, It also includes step S7, which establishes a temperature-precipitation correlation model based on the temperature change rate dT / dt and the precipitation accumulation rate dM / dt, to predict precipitation formation trends or optimize battery operating conditions.

9. The integrated fiber optic dual-parameter seawater metal-air battery monitoring method according to claim 7, characterized in that, In step S1, the wavelength-stress correspondence is established by applying precipitates of different masses to the surface of the oxygen reduction cathode, recording the wavelength offset of the corresponding first fiber Bragg grating, and fitting the stress sensitivity coefficient. The wavelength-temperature correspondence in step S1 is established by placing the second fiber Bragg grating in a constant temperature environment, recording its reflected wavelength at different temperature points, and fitting the temperature sensitivity coefficient.

10. The application of the integrated fiber optic dual-parameter seawater metal-air battery monitoring system according to any one of claims 1 to 6 in marine equipment energy management.

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