Lithium battery electrolyte multi-component in-situ Raman detection system and method based on micro-cavity optical fiber probe

Abstract

The invention belongs to the technical field of lithium ion battery detection, and particularly discloses a lithium battery electrolyte multi-component in-situ Raman detection system based on a microcavity optical fiber probe, which comprises an open microcavity optical fiber probe, a wavelength-switchable laser light source module, a Raman spectrometer and a battery management system, the open type micro-cavity optical fiber probe comprises an excitation optical fiber and a receiving optical fiber which are arranged in parallel to form an open type micro-cavity which is vertical to the axial direction of the optical fiber and is provided with an upper opening and a lower opening; the wavelength-switchable laser light source module is coupled with the excitation optical fiber; the Raman spectrometer is in light path connection with the receiving optical fiber and is used for collecting and storing a Raman spectrum; and the battery management system is used for synchronously controlling the charging and discharging states of the battery and triggering a spectrum acquisition time sequence. According to the method, the component concentration evolution of the electrolyte can be tracked in real time in the charging and discharging process, and an in-situ detection means is provided for battery health state evaluation, service life prediction and safety early warning.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery detection technology, specifically relating to a multi-component in-situ Raman detection system and method for lithium battery electrolyte based on a microcavity fiber optic probe. Background Technology

[0002] The performance and safety of lithium-ion batteries rely heavily on the chemical stability of the electrolyte. During battery cycling, the electrolyte is prone to irreversible decomposition, additive depletion, and byproduct accumulation, leading to capacity decay, increased internal resistance, and a significantly increased risk of thermal runaway. Therefore, accurate analysis of the electrolyte's chemical state is crucial for battery performance optimization and safety assurance. Current electrolyte analysis primarily employs traditional methods such as gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). These methods require offline sampling after battery disassembly, which has three major drawbacks: First, offline detection cannot reflect the dynamic chemical evolution of the electrolyte under actual battery operating conditions; second, disassembly damages the battery's sealed structure, allowing external impurities such as moisture and oxygen to infiltrate and cause contamination, resulting in distorted analytical results; and third, the detection process is cumbersome and time-consuming, making it difficult to meet the actual needs of real-time status diagnosis and intelligent early warning during battery operation.

[0003] Raman spectroscopy, with its unique advantages of strong specificity in molecular vibrational fingerprints and non-contact, non-destructive testing, can be used for in-situ analysis and detection of electrolytes. However, integrating it into the interior of a sealed lithium-ion battery for in-situ detection still faces three major technical bottlenecks: First, the limited space inside the battery and the highly corrosive nature of the electrolyte make it difficult to achieve long-term stable integration with traditional optical probes; second, the electrode materials inside the battery (such as lithium iron phosphate, NCM (lithium nickel cobalt manganese oxide)) and conductive carbon black easily generate strong background fluorescence and Mie scattering, severely masking the weak Raman signal of the electrolyte, resulting in an extremely low signal-to-noise ratio; third, in existing single-fiber configurations, the excitation light and Raman scattering light are transmitted in a common path, and the background noise intensity generated by reflection from the fiber end face can reach 10 times that of the target Raman signal. 3 -10 4 This doubles the signal, causing the effective signal to be completely drowned out.

[0004] While existing patent CN202511244784 mentions using fiber optic sensing technology for battery temperature or strain monitoring, it does not address the specific Raman identification of electrolyte components, thus failing to solve the problem of in-situ electrolyte analysis. Another technology employs surface-enhanced Raman scattering (SERS) to improve detection sensitivity, but this approach has inherent drawbacks: the SERS substrate exhibits poor long-term stability in electrochemical environments, low detection repeatability, and is prone to electrochemical oxidation or catalytic side reactions. Furthermore, it lacks an effective physical isolation mechanism against interference from solid electrodes, making it difficult to meet practical application requirements.

[0005] In summary, there is an urgent need to develop a miniaturized and highly stable Raman probe structure that can construct a pure and isolated optical detection micro-region inside the battery, effectively shielding background interference from components such as electrodes, and enabling in-situ, real-time, and non-destructive quantitative analysis of electrolyte components. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-component in-situ Raman detection system and method for lithium battery electrolytes based on a microcavity fiber optic probe. The system employs an open microcavity probe composed of parallel-arranged excitation and receiving fibers, which allows the electrolyte to diffuse freely and effectively collect Raman signals. It is suitable for the sealed integration process of pouch or stacked batteries, solving the leakage and corrosion problems caused by fiber optic implantation. A hybrid Raman spectroscopy decoupling algorithm is established, and multi-component synchronous quantitative analysis is achieved through a standard Raman characteristic peak database and concentration calibration curves for components such as LiPF6, EC, DMC, and FEC.

[0007] To achieve the above objectives, one of the technical solutions of the present invention is: a multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe, comprising an open microcavity fiber optic probe, a switchable wavelength laser source module, a Raman spectrometer, and a battery management system (BMS). The open microcavity fiber optic probe comprises an excitation fiber and a receiving fiber arranged in parallel, forming an open microcavity with upper and lower openings perpendicular to the fiber axis. The switchable wavelength laser source module is coupled to the excitation fiber. The Raman spectrometer is connected to the receiving fiber optical path for acquiring and storing Raman spectra. The battery management system is used to synchronously control the battery charging and discharging state and trigger the spectral acquisition timing.

[0008] In a preferred embodiment of the present invention, the in-situ Raman detection system further includes a data processing module for executing a multi-component spectral decoupling algorithm, outputting the real-time concentration of each electrolyte component, and performing correlation analysis with battery capacity decay, internal resistance change, or temperature data to achieve dynamic assessment of battery state of health (SOH).

[0009] In a preferred embodiment of the present invention, both the excitation fiber and the receiving fiber are multimode fibers with an outer diameter of 125±2 μm, a core diameter of 105±2 μm, and a numerical aperture of 0.2-0.3.

[0010] In a preferred embodiment of the present invention, the excitation optical fiber and the receiving optical fiber are flush at the end face of the detection end, and their cross-sections are located on the same horizontal plane.

[0011] In a preferred embodiment of the present invention, the open microcavity fiber optic probe further includes a microstructure support for fixing the ends of the excitation fiber and the receiving fiber and maintaining the preset gap. The open microcavity is formed by the cores of the excitation fiber and the receiving fiber together with the microstructure support, and the upper and lower openings of the open microcavity face the electrolyte region inside the battery.

[0012] In a preferred embodiment of the present invention, the open microcavity has a height of 105–125 μm, a width of 210–240 μm, and a length of 5–10 mm.

[0013] In a preferred embodiment of the present invention, the inner surface of the open microcavity is a chemically inert material selected from silicon dioxide or single crystal silicon, and the detection chamber at its end can be formed by processing microgrooves at the end.

[0014] To achieve the above objectives, the second technical solution of the present invention is: a detection method for a multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe, comprising the following steps: S1: An open microcavity probe, formed by parallel arrangement of excitation and receiving fibers, is implanted inside the lithium battery to allow the electrolyte to freely diffuse in and physically isolate the electrode active materials; S2: A heat-sealing adhesive compatible with the battery tab adhesive is used to heat-seal the fiber lead-out portion, allowing the heat-sealing adhesive to melt and interpenetrate with the polypropylene inner layer of the aluminum-plastic film, forming a molecular-level sealed interface to achieve airtight sealing of the battery; S3: During battery charging and discharging, a laser transmitted through the excitation fiber irradiates the microcavity region, exciting the electrolyte to generate Raman scattering, and the receiving fiber collects the Raman scattering spectrum; S4: Based on a pre-constructed standard Raman characteristic peak database and concentration-intensity calibration curve, a multivariate linear decoupling analysis is performed on the collected mixed Raman spectrum to quantitatively obtain the concentration information of each component in the electrolyte.

[0015] In a preferred embodiment of the present invention, the heat-sealing adhesive in step S1 is a modified hot-melt resin, whose softening temperature matches that of the polypropylene inner layer of the aluminum-plastic film, and is resistant to electrolyte corrosion. The heat-sealing temperature is 180-220°C, and the time is 2-8 seconds, so that the tab adhesive and the aluminum-plastic film melt and interpenetrate to form a molecular-level sealed interface, ensuring the airtightness of the optical fiber outlet and making the battery completely sealed.

[0016] In a preferred embodiment of the present invention, the laser excitation wavelength in step S3 is 532 nm or 785 nm, the laser power is 1–200 mW, and the spectral acquisition integration time is 1–600 s.

[0017] In a preferred embodiment of the present invention, the standard Raman characteristic peak database in step S4 contains characteristic peaks of the following components:

[0018] LiPF6 anion PF6 - 735–745 cm -1 ;

[0019] Ethylene carbonate (EC): 890–900 cm -1 With 1780–1800 cm -1 ;

[0020] Dimethyl carbonate (DMC): 910–925 cm -1 ;

[0021] Vinyl carbonate (VC): 1620–1640 cm -1 ;

[0022] Vinyl fluorocarbonate (FEC): 1040–1060 cm -1 .

[0023] In a preferred embodiment of the present invention, the concentration-intensity calibration curve in step S4 is constructed using the external standard method or the internal standard method, and the linear correlation coefficient R of each component is... 2 It has an ≥0.98 and exhibits a linear response in the concentration range of 0.1–10 wt%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention employs a "dual-fiber strategy" that physically separates the excitation fiber and the receiving fiber, effectively avoiding strong background reflection interference in the single-fiber scheme. Furthermore, the specially designed detection chamber isolates the influence of solid particles on the electrodes, significantly reducing background signal interference.

[0026] 2. The open-cavity fiber optic probe of this invention can be implanted inside the battery for a long time, enabling real-time, in-situ, and non-destructive testing of the electrolyte without interrupting battery operation or performing destructive sampling.

[0027] 3. This invention uses an excitation fiber and a receiving fiber to form a physical optical detection microcavity, which greatly improves the stability of the acquisition method through its simple structure, resulting in small batch differences and good long-term stability.

[0028] 4. The probe of this invention has a compact structure and can be compatible with various battery configurations such as stacked and cylindrical cells through optimized implantation processes, making it easy to integrate with battery management systems. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the detection system in Example 1;

[0030] Figure 2 This is a schematic diagram of the end face structure of the open microcavity fiber optic probe in Example 1;

[0031] Figure 3 This is a physical image of the open microcavity fiber optic probe from Example 1.

[0032] Figure 4 Example diagram of standard curves for electrolyte component concentration in Example 2: (1) Raman spectra of electrolytes with different VC concentrations; (2) Fitting diagram of standard curves for VC characteristic peak area-concentration.

[0033] Figure 5 This is the in-situ Raman spectral evolution diagram of the lithium iron phosphate battery in Example 2 during the charging and discharging process;

[0034] Figure 6 This is a diagram showing the long-cycle capacity of the lithium iron phosphate battery in Example 2. Detailed Implementation

[0035] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0036] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", "vertical", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the perspective view in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Example 1

[0038] A multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe, such as Figure 1-3 As shown, the system includes an open microcavity fiber optic probe, a switchable wavelength laser source module, a Raman spectrometer, and a battery management system. The open microcavity fiber optic probe consists of parallel excitation and receiving fibers, forming an open microcavity with openings at the top and bottom perpendicular to the fiber axis. The switchable wavelength laser source module is coupled to the excitation fiber. The Raman spectrometer is connected to the receiving fiber optical path for acquiring and storing Raman spectra. The battery management system is used to synchronously control the battery's charging and discharging state and trigger the spectral acquisition sequence. This in-situ Raman detection system also includes a data processing module for executing a multi-component spectral decoupling algorithm, outputting the real-time concentration of each electrolyte component, and performing correlation analysis with battery capacity decay, internal resistance change, or temperature data to achieve dynamic assessment of battery health.

[0039] The open-cavity microcavity fiber optic probe is a dual-fiber microcavity probe, with both the excitation and receiving fibers being multimode silica fibers. Both fibers have an outer diameter of 125±2 μm, a core diameter of 105±2 μm, and a numerical aperture of 0.22 to ensure optical path matching and signal acquisition efficiency. The excitation and receiving fibers are flush at the detection end, and their cross-sections are located on the same horizontal plane.

[0040] The fabrication method of the open microcavity fiber optic probe includes the following steps:

[0041] (1) End face treatment and alignment: The two optical fiber end faces are vertically cut with a high-precision optical fiber cleaver (cutting angle error ≤ 0.5°) to obtain a flat optical end face; then, the two optical fibers are fixed side by side on a quartz substrate using a micro-manipulation platform so that the fiber core center is located on the same horizontal plane, ensuring that the excitation light and the receiving optical axis are coplanar and improving the coupling efficiency.

[0042] (2) Construction of open microcavity structure: The spacing between the two fiber cores was adjusted by a precision micro-displacement platform to control the spacing to 5.0±0.5 mm. This spacing was experimentally verified as the optimal range: firstly, it ensures that the electrolyte can freely convection and diffuse within the microcavity; secondly, it ensures that the Raman scattered light is efficiently captured by the receiving fiber, avoiding signal attenuation.

[0043] (3) Open microcavity encapsulation and structure definition: A polyimide sleeve (inner diameter 130 μm) resistant to electrolyte corrosion is sleeved on the outside of the two optical fibers. UV curing adhesive is dropped onto both ends of the sleeve and cured by 365 nm UV light for 30 s to form an open microcavity structure.

[0044] The open microcavity fiber optic probe also includes a microstructure support for fixing the ends of the excitation and receiving fibers and maintaining the preset gap. The open microcavity is formed by the cores of the excitation and receiving fibers together with the microstructure support. The upper and lower openings of the open microcavity face the electrolyte region inside the battery. The open microcavity has a height of 105 μm, a width of 210 μm, and a length of 10 mm. The inner surface of the open microcavity is made of a chemically inert material, namely silicon dioxide, and the detection chamber at its end can be formed by machining microgrooves at the end.

[0045] The excitation fiber is used to conduct the excitation laser to the open microcavity region, irradiating electrolyte molecules to generate Raman scattering; the receiving fiber is dedicated to collecting the scattered light signal and transmitting it to the spectrometer. The two fibers are completely separated, thoroughly avoiding the Rayleigh scattering background interference problem caused by the co-path transmission of excitation light and Raman signal in traditional single-fiber systems, and significantly improving the signal-to-noise ratio.

[0046] Example 2

[0047] A detection method for a multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe includes the following steps:

[0048] S1: Microcavity Fiber Optic Probe Implantation: An open-cavity probe, formed by parallel arrangement of excitation and receiving fibers, is implanted inside a lithium battery. The lithium battery used is a 114.6 mAh / g lithium iron phosphate / graphite pouch battery (positive electrode material is LiFePO4, negative electrode material is graphite). The length can be adjusted according to the implantation location. In this embodiment, the pouch battery is 120 mm long and 60 mm wide. The implantation location is selected according to the detection requirements. Optional locations include between the positive and negative electrode plates and the aluminum-plastic film, between the positive and negative electrode plates and the separator layer (for interface reaction monitoring), near the injection port (for initial wetting process observation), or other areas of interest. In this embodiment, the probe is implanted between the positive electrode and the separator. After implantation, the probe is fixed by a clamp to ensure that it maintains a stable position inside the battery and avoids displacement due to thermal expansion and contraction. The open-cavity microcavity allows the electrolyte to diffuse freely into the battery while physically isolating the electrode active materials to avoid background interference from electrode components.

[0049] S2: Battery Sealing Integration Process: A heat-sealing adhesive compatible with the battery tab material is used, namely a multi-layer composite encapsulating adhesive made of the same material as the positive / negative electrode tabs of the battery. It is composed of reinforced modified resin, with an edge layer softening temperature of 116℃ and an interlayer heat softening temperature of 175℃. It has excellent heat-sealing properties, resistance to electrolyte corrosion, and mechanical strength. The fiber optic lead-out area is pre-treated by wrapping the fiber optic probe lead-out section (approximately 2–3 mm area) with the encapsulating adhesive from top to bottom. Subsequently, during the aluminum-plastic film encapsulation stage of the soft-pack battery assembly, the fiber optic probe lead-out end is aligned with the reserved protrusion position, and a standard heat-sealing process is performed: heat-sealing temperature 220℃, pressure 0.4 MPa, time 8 s. This allows the heat-sealing adhesive and the inner polypropylene (PP) layer of the aluminum-plastic film to melt and interpenetrate simultaneously. After cooling and solidification, a molecularly fused sealing interface is formed. This sealing structure has the same airtightness and durability as the battery tab area, effectively preventing electrolyte from seeping along the gaps during liquid injection, thus achieving an airtight seal for the battery.

[0050] S3: In-situ Raman spectroscopy acquisition: Electrolyte (specific ratio: 1M LiPF6 inEC:DMC:EMC = 1:1:1, containing 5 wt% vinylene carbonate additive, electrolyte injection volume 750 μL) is injected into the sealed battery; the battery is charged and discharged in cycles. During the cycle, the open microcavity region is irradiated by a laser transmitted through an excitation fiber to excite the electrolyte to generate Raman scattering, and the Raman scattering spectrum is acquired by a receiving fiber; the laser excitation wavelength is 785 nm, the laser power is 50 mW, the spectral acquisition integration time is 30 s, and Raman spectra are acquired every 10 min. Each acquisition is repeated 3 times and the average value is taken to improve the reliability of the spectrum.

[0051] S4: Multi-component quantitative analysis: Based on a pre-constructed standard Raman characteristic peak database and concentration-intensity calibration curves, multivariate linear decoupling analysis is performed on the acquired mixed Raman spectra to quantitatively obtain the concentration information of each component in the electrolyte; specifically including the following sub-steps:

[0052] (1) Preparation of standard samples: Prepare standard electrolytes with concentration gradients of 0.1, 0.2, 0.4, 0.8, 1, 2, 4, 5, 8, and 10 wt% for the target analytical component vinylene carbonate (VC), and set up 3 parallel samples for each concentration group;

[0053] (2) Establishment of standard curve: The Raman spectrum of the standard electrolyte is obtained using the same spectral acquisition parameters as in step S3. The concentration-intensity calibration curve is constructed by using the characteristic peak intensity of each component as the ordinate and the concentration as the abscissa, through the external standard method or the internal standard method. The linear correlation coefficient R of each component is required to be... 2 ≥0.98, of which VC is 1625 cm -1 Construct curves from characteristic peaks, R 2 =0.99;

[0054] (3) Mixed spectral decoupling and quantification: The in-situ Raman spectrum collected in step S3 is substituted into the standard Raman characteristic peak database for matching and identification. The standard Raman characteristic peak database contains characteristic peaks of the following components: LiPF6 anion PF6 - (735–745 cm) -1 ), ethylene carbonate (EC, 890–900 cm) -1 With 1780–1800 cm -1 ), dimethyl carbonate (DMC, 910–925 cm⁻¹) -1 ), vinylene carbonate (VC, 1620–1640 cm⁻¹) -1 ), vinyl fluorocarbonate (FEC, 1040–1060 cm⁻¹) -1 The characteristic peak signals of each component are separated by multivariate linear decoupling analysis, and the real-time concentration information of each component is calculated by combining the corresponding concentration-intensity calibration curve.

[0055] Figure 4 Here are examples of standard curves for electrolyte component concentrations: (1) Raman spectra of electrolytes with different VC concentrations; (2) fitting graph of VC characteristic peak area-concentration standard curve. From the graphs, it can be seen that the characteristic peak of VC is at 1620 cm⁻¹. -1 The characteristic peaks, attributed to the stretching vibrations of -CH=CH-, were linearly fitted to a standard curve based on the Raman spectra of electrolytes with different VC concentrations. The resulting R0... 2 Above 0.98, there is a good linear relationship, based on which the mathematical quantitative relationship between the spectral peak and the concentration is obtained.

[0056] Figure 5 The image shows the in-situ Raman spectral evolution of a lithium iron phosphate battery during charge and discharge. As can be seen from the image, this method can quantitatively detect the evolution of Raman characteristic peaks of the electrolyte solvent (EC / DMC / EMC) in real time during charge and discharge, from 890 to 920 cm⁻¹. -1 The EC ring breathing vibration increases with increasing potential, reflecting the dynamic changes in the reorganization of the lithium-ion solvation shell structure and the orientation polarization of solvent molecules at the interface. The intensity of each solvent peak decreases during discharge, and the Raman spectrum of the electrolyte is consistent with the initial state, indicating that the electrolyte components do not undergo irreversible decomposition on the positive electrode surface. The evolution of the solvation structure is highly coupled with the lithium-ion insertion / extraction process and has good electrochemical reversibility. The VC content remains stable after the first cycle, indicating that after the SEI layer is formed, the additives do not participate in the lithium-ion insertion / extraction reaction.

[0057] Figure 6 The graph shows the long-cycle capacity of a lithium iron phosphate battery. As can be seen from the graph, the battery can cycle stably for about 150 cycles without any change in coulombic efficiency. After 150 cycles, the capacity retention rate is about 95%, proving that embedding optical fibers in the battery has almost no effect on the specific capacity of the lithium battery.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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 the present invention.

Claims

1. A multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe, characterized in that, The system includes an open microcavity fiber optic probe, a switchable wavelength laser source module, a Raman spectrometer, and a battery management system. The open microcavity fiber optic probe consists of parallel excitation and receiving fibers, forming an open microcavity with openings at the top and bottom perpendicular to the fiber axis. The switchable wavelength laser source module is coupled to the excitation fiber. The Raman spectrometer is connected to the receiving fiber optical path for acquiring and storing Raman spectra. The battery management system is used to synchronously control the battery charging and discharging state and trigger the spectral acquisition timing.

2. The in-situ Raman detection system for multi-component lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 1, characterized in that, The in-situ Raman detection system also includes a data processing module.

3. The in-situ Raman detection system for multi-component lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 1, characterized in that, The excitation fiber and the receiving fiber are flush at the end face of the detection end, and their cross-sections are located on the same horizontal plane; both the excitation fiber and the receiving fiber are multimode fibers with an outer diameter of 125±2 μm, a core diameter of 105±2 μm, and a numerical aperture of 0.2-0.

3.

4. The in-situ Raman detection system for multi-component lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 1, characterized in that, The open microcavity fiber optic probe also includes a microstructure support. The open microcavity is formed by the cores of the excitation fiber and the receiving fiber together with the microstructure support. The upper and lower openings of the open microcavity face the electrolyte region inside the battery.

5. The in-situ Raman detection system for multi-component lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 1, characterized in that, The open microcavity has a height of 105–125 μm, a width of 210–240 μm, and a length of 5–10 mm. The inner surface of the open microcavity is made of a chemically inert material selected from silicon dioxide or single-crystal silicon. The detection chamber at its end can be formed by processing microgrooves at the end.

6. The detection method of the multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: An open microcavity probe, consisting of excitation and receiving optical fibers arranged in parallel, is implanted inside the lithium battery to allow the electrolyte to diffuse freely and physically isolate the electrode active materials; S2: A heat-sealing adhesive compatible with the battery tab adhesive is used to heat-seal the fiber lead-out area, allowing the heat-sealing adhesive to melt and interpenetrate with the polypropylene inner layer of the aluminum-plastic film, forming a molecular-level sealed interface to achieve the battery's airtightness; S3: During the battery's charging and discharging process, a laser transmitted through the excitation fiber irradiates the microcavity region, exciting the electrolyte to generate Raman scattering, and the receiving fiber collects the Raman scattering spectrum; S4: Based on a pre-constructed database of standard Raman characteristic peaks and concentration-intensity calibration curves, multivariate linear decoupling analysis is performed on the acquired mixed Raman spectra to quantitatively obtain the concentration information of each component in the electrolyte.

7. The detection method of the multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 6, characterized in that, The heat-sealing adhesive used in step S1 is a modified hot melt resin, with a heat-sealing temperature of 180-220℃ and a time of 2-8 seconds.

8. The detection method of the multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 6, characterized in that, In step S3, the laser excitation wavelength is 532 nm or 785 nm, the laser power is 1–200 mW, and the spectral acquisition integration time is 1–600 s.

9. The detection method of the multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 6, characterized in that, The standard Raman characteristic peak database in step S4 contains characteristic peaks of the following components: LiPF6 anion PF6 - 735–745 cm -1 ; Ethylene carbonate (EC): 890–900 cm -1 With 1780–1800 cm -1 ; Dimethyl carbonate (DMC): 910–925 cm -1 ; Vinyl carbonate (VC): 1620–1640 cm -1 ; Vinyl fluorocarbonate (FEC): 1040–1060 cm -1 .

10. The detection method of the multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity fiber optic probe as described in claim 6, characterized in that, The concentration-intensity calibration curve in step S4 is constructed using the external standard method or the internal standard method, and the linear correlation coefficient R of each component is... 2 It has an ≥0.98 and exhibits a linear response in the concentration range of 0.1–10 wt%.

Images