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CN-121994777-A - Lithium battery electrolyte multicomponent in-situ Raman detection system and method based on microcavity type optical fiber probe

CN121994777ACN 121994777 ACN121994777 ACN 121994777ACN-121994777-A

Abstract

The invention belongs to the technical field of lithium ion battery detection, and particularly discloses a lithium battery electrolyte multicomponent in-situ Raman detection system based on a microcavity type optical fiber probe, which comprises an open microcavity type optical fiber probe, a laser light source module capable of switching wavelengths, 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 with upper and lower openings perpendicular to the axial direction of the optical fiber, the laser light source module capable of switching wavelengths is coupled with the excitation optical fiber, the Raman spectrometer is connected with the optical path of the receiving optical fiber and used for collecting and storing Raman spectra, and the battery management system is used for synchronously controlling the charge and discharge states of a battery and triggering spectrum collection time sequences. The invention can track the component concentration evolution of the electrolyte in real time in the charge and discharge process, and provides an in-situ detection means for the evaluation of the health state, the prediction of the service life and the safety early warning of the battery.

Inventors

  • LI JIANFENG
  • GAO CHENHAO
  • DONG JINCHAO

Assignees

  • 厦门大学

Dates

Publication Date
20260508
Application Date
20260318

Claims (10)

  1. 1. A lithium battery electrolyte multicomponent in-situ Raman detection system based on a microcavity type optical fiber probe is characterized by comprising an open microcavity type optical fiber probe, a laser light source module with switchable wavelength, a Raman spectrometer and a battery management system, wherein the open microcavity type optical fiber probe comprises an excitation optical fiber and a receiving optical fiber which are arranged in parallel to form an open microcavity with upper and lower openings perpendicular to the axial direction of the optical fiber, the laser light source module with the switchable wavelength is coupled with the excitation optical fiber, the Raman spectrometer is connected with a receiving optical fiber optical path and is used for collecting and storing Raman spectra, and the battery management system is used for synchronously controlling the charge and discharge states of a battery and triggering spectrum collection time sequences.
  2. 2. The microcavity fiber optic probe based lithium battery electrolyte multicomponent in situ raman detection system of claim 1 wherein the in situ raman detection system further comprises a data processing module.
  3. 3. The multi-component in-situ Raman detection system for the lithium battery electrolyte based on the microcavity type optical fiber probe, as set forth in claim 1, is characterized in that the end faces of the excitation optical fiber and the receiving optical fiber at the detection end are flush, the cross sections of the excitation optical fiber and the receiving optical fiber are positioned on the same horizontal plane, the excitation optical fiber and the receiving optical fiber are multimode optical fibers, the outer diameter is 125+/-2 microns, the fiber core diameter is 105+/-2 microns, and the numerical aperture is 0.2-0.3.
  4. 4. The microcavity fiber optic probe-based lithium battery electrolyte multicomponent in situ raman detection system of claim 1 wherein the open microcavity fiber optic probe further comprises a microstructure support, the open microcavity is defined by the excitation fiber and the core of the receiving fiber and the microstructure support, and the upper and lower openings of the open microcavity are oriented toward the battery interior electrolyte region.
  5. 5. The multi-component in-situ Raman detection system for lithium battery electrolyte based on a microcavity type optical fiber probe according to claim 1, wherein the open microcavity has a height of 105-125 μm, a width of 210-240 μm and a length of 5-10 mm, and the inner surface of the open microcavity is made of a chemically inert material selected from silicon dioxide or monocrystalline silicon, and the detection chamber at the end of the open microcavity can be formed by end processing of a microgroove.
  6. 6. The detection method of the multi-component in-situ Raman detection system of the lithium battery electrolyte based on the microcavity optical fiber probe is characterized by comprising the following steps of S1, implanting an open microcavity probe formed by arranging an excitation optical fiber and a receiving optical fiber in parallel into a lithium battery to enable the electrolyte to freely diffuse into and physically isolate electrode active materials, S2, performing heat sealing treatment on an optical fiber leading-out part by using heat sealing glue compatible with battery lug glue materials to enable the heat sealing glue and polypropylene in an inner layer of an aluminum plastic film to melt and mutually infiltrate to form a molecular-level sealing interface, realizing airtight sealing of the battery, S3, transmitting laser through the excitation optical fiber to irradiate a microcavity area, exciting the electrolyte to generate Raman scattering, and collecting Raman scattering spectra by the receiving optical fiber, and S4, performing multi-element linear decoupling analysis on the collected mixed Raman spectra based on a pre-built standard Raman characteristic peak database and a concentration-intensity calibration curve, and quantitatively obtaining concentration information of each component in the electrolyte.
  7. 7. The detection method of the microcavity fiber optic probe-based multi-component in-situ Raman detection system for lithium battery electrolyte of claim 6, wherein the heat sealing glue in the step S1 is modified hot melt resin, the heat sealing temperature is 180-220 ℃, and the time is 2-8S.
  8. 8. The detection method of the microcavity fiber optic probe-based multi-component in situ Raman detection system for lithium battery electrolyte according to claim 6, wherein the laser excitation wavelength in the step S3 is 532 nm or 785nm, the laser power is 1-200 mW, and the spectrum acquisition integration time is 1-600S.
  9. 9. The detection method of the microcavity fiber optic probe-based multi-component in situ raman detection system for lithium battery electrolytes according to claim 6 wherein the standard raman characteristic peak database in step S4 comprises characteristic peaks of the following components: LiPF 6 anion PF 6 - ：735–745 cm -1 ; Ethylene Carbonate (EC) 890-900 cm -1 and 1780-1800 cm -1 ; Dimethyl carbonate (DMC) 910-925 cm -1 ; Vinylene Carbonate (VC) 1620-1640 cm -1 ; Fluoroethylene carbonate (FEC) 1040-1060 cm -1 .
  10. 10. The detection method of the microcavity fiber optic probe-based multi-component in-situ Raman detection system for lithium battery electrolyte according to claim 6, wherein the concentration-intensity calibration curve in the step S4 is constructed by an external standard method or an internal standard method, and the linear correlation coefficient R 2 of each component is more than or equal to 0.98 and has linear response in the concentration range of 0.1-10 wt%.

Description

Lithium battery electrolyte multicomponent in-situ Raman detection system and method based on microcavity type optical fiber probe Technical Field The invention belongs to the technical field of lithium ion battery detection, and particularly relates to a lithium battery electrolyte multicomponent in-situ Raman detection system and method based on a microcavity type optical fiber probe. Background The performance and the safety of the lithium ion battery are based on the chemical stability of electrolyte, and the electrolyte is easy to generate irreversible decomposition, additive consumption, byproduct accumulation and other phenomena in the battery circulation process, so that the capacity attenuation and the internal resistance of the battery are improved, and the thermal runaway risk is obviously increased, so that the accurate analysis of the chemical state of the electrolyte is very important for the performance optimization and the safety guarantee of the battery. The existing electrolyte analysis mainly adopts traditional methods such as gas chromatography-mass spectrometry, nuclear magnetic resonance and the like, and the method needs to disassemble a battery and then sample the battery offline, so that the method has three defects that firstly, an offline detection mode cannot reflect the dynamic chemical evolution process of the electrolyte under the real working condition of the battery, secondly, the disassembly operation can damage the closed structure of the battery, so that external impurities such as moisture, oxygen and the like invade to pollute the battery, and the analysis result is distorted, thirdly, the detection flow is complicated, the period is long, and the actual requirements of real-time state diagnosis and intelligent early warning in the operation process of the battery are difficult to meet. The Raman spectrum technology can be used for in-situ analysis and detection of electrolyte by virtue of the unique advantages of strong specificity, non-contact and nondestructive detection of molecular vibration 'fingerprint', but when the Raman spectrum technology is integrated in a sealed lithium ion battery to implement in-situ detection, three key technical bottlenecks are faced, namely, firstly, the internal space of the battery is limited, the electrolyte has strong corrosiveness, the traditional optical probe is difficult to realize long-term stable integration, secondly, components such as an internal electrode material (such as lithium iron phosphate, NCM (nickel cobalt lithium manganate)) of the battery, conductive carbon black and the like easily generate strong background fluorescence and Mi scattering, the weak Raman signal of the electrolyte is seriously covered, the detection signal-to-noise ratio is extremely low, thirdly, in the existing single optical fiber configuration, the intensity of background noise generated by the reflection of the end face of an optical fiber can reach 10 3–104 times of a target Raman signal, and an effective signal is completely submerged. Although the prior patent CN202511244784 mentions that the optical fiber sensing technology is used for monitoring the temperature or strain of the battery, specific raman recognition of electrolyte components is not involved, and the problem of in-situ analysis of the electrolyte cannot be solved. In addition, the detection sensitivity is improved by adopting a Surface Enhanced Raman Scattering (SERS) scheme, but the SERS substrate has the inherent defects of poor long-term stability and low detection repeatability in an electrochemical environment, is easy to generate electrochemical oxidation or catalytic side reaction, and meanwhile, lacks an effective physical isolation mechanism for solid electrode interference, so that the practical application requirement is difficult to meet. In summary, there is a need to develop a miniaturized and high-stability raman probe structure, which can construct a pure and isolated optical detection micro-area in a battery, effectively shield the background interference of components such as an electrode and the like, and realize in-situ, real-time and nondestructive quantitative analysis of electrolyte components. Disclosure of Invention The invention aims to overcome the defects of the prior art, provides a lithium battery electrolyte multicomponent in-situ Raman detection system and method based on a microcavity type optical fiber probe, adopts an open microcavity type probe formed by arranging excitation optical fibers and receiving optical fibers in parallel, allows the electrolyte to diffuse freely and effectively collect Raman signals, is suitable for a sealed integration process of a soft package or laminated battery, solves the problems of liquid leakage and corrosion caused by optical fiber implantation, establishes a hybrid Raman spectrum decoupling algorithm, and realizes multicomponent synchronous quantitative analysis through a standard Raman characteristi