In-situ detection method for SPR (Surface Plasmon Resonance) type optical fiber ion battery based on MXene modification

Abstract

The invention is applicable to the field of optical fiber sensors and the field of in-situ detection of ion batteries, and provides an in-situ detection method for an SPR type optical fiber ion battery based on MXene modification, which comprises the following steps: placing a micro-nano optical fiber sensor in the ion battery and fully contacting the micro-nano optical fiber sensor with electrolyte; when the battery works, the ion concentration change rule is mapped through the wavelength response distance of the reflection spectrum of the micro-nano optical fiber sensor so as to realize battery health state detection; the micro-nano optical fiber sensor is a high-sensitivity optical fiber sensing device based on an MXene composite gold nanoparticle (AuNPs) modified micro-nano optical fiber accompanying excitation surface plasma resonance (SPR) absorption peak phenomenon, MXene serves as an important candidate material of a new-generation energy storage and electrochemical device, and has stable electrochemical characteristics of electric conduction, energy storage, catalysis and the like; according to the invention, long-term structural stability can be maintained in a battery electrolyte environment, AuNPs can be firmly compounded on the basis of characteristics of rich functional groups on the surface, a multilayer structure and the like, and an SPR effect is excited on the surface of the micro-nano optical fiber, so that the detection sensitivity and the cycling stability of the sensor under long-term working of a battery are remarkably improved. According to the embodiment provided by the invention, high-sensitivity detection of the ion concentration in the battery can be realized, and the prepared sensor can be used for health state evaluation of energy storage batteries such as a lithium ion battery and a sodium ion battery.

Description

Technical Field

[0001] The present invention relates to the field of in-situ detection of batteries, and in particular to a method for in-situ detection of SPR-type optical fiber ion batteries based on MXene modification. Background Art

[0002] With the rapid development of new energy technologies, ion batteries, as highly efficient energy storage devices, are widely used in electric vehicles, portable electronic devices, and large-scale energy storage systems. However, complex chemical reactions occur during the charge and discharge process of ion batteries. Changes in internal ion concentration, electrode material structure, and electrolyte state directly affect battery performance and safety. Therefore, real-time monitoring of the internal chemical state of ion batteries is crucial for optimizing battery performance, extending service life, and preventing safety incidents.

[0003] Traditional battery testing methods include electrochemical impedance spectroscopy and cyclic voltammetry, all of which require external electrode intervention or destructive sampling to analyze the parameters to be measured to evaluate the health life of the battery. These testing methods ensure measurement accuracy, but it is difficult to achieve in-situ dynamic monitoring of the battery during operation. In addition, the complex chemical environment inside the battery also places extremely high demands on the corrosion resistance and sensitivity of the testing equipment.

[0004] Fiber optic sensors are becoming increasingly powerful tools for ion battery testing due to their high sensitivity, resistance to electromagnetic interference, miniaturization, and remote monitoring capabilities. Previous studies have utilized surface plasmon resonance (SPR) fiber optic sensors, which place the SPR sensor near electrodes and electrolytes to detect changes in ion concentrations. However, conventional SPR sensitive layers are susceptible to failure in the high-temperature, highly corrosive environment of batteries and lack the ability to respond to electrochemical interfacial reactions, limiting their application in battery testing. Therefore, developing a highly sensitive, interference-resistant fiber optic in-situ battery detection device is of great significance to the development of lithium batteries. Summary of the Invention

[0005] The purpose of the present invention is to address the needs of ion batteries in optical fiber in-situ detection technology, and to provide an in-situ detection method for optical fiber ion batteries based on MXene modification. By implanting a highly integrated and highly sensitive micro-nano optical fiber sensor into the battery, and based on the MXene composite gold nanoparticles (AuNPs) modified micro-nano optical fiber coupling region accompanied by the excited surface plasmon resonance (SPR) absorption peak phenomenon, the in-situ detection of ion concentration is achieved, thereby realizing the detection of battery health status.

[0006] The technical solutions adopted are as follows:

[0007] A MXene-modified SPR-type optical fiber ion battery in-situ detection method comprises a light source (1), an optical fiber isolator (2), an incident optical fiber (3), a micro-nano optical fiber sensor (4), an ion battery (5), a reflecting optical fiber (6), an optical fiber amplifier (7), a spectrometer (8), and a computer (9); the micro-nano optical fiber sensor (4) comprises a micro-nano optical fiber coupler (4-1), a functionalized film (4-2), an incident end (4-3), and a reflective metal film (4-5) plated at the end of a reflecting end (4-4);

[0008] In one embodiment, the sensing system sequentially connects a light source (1), an optical fiber isolator (2), an incident optical fiber (3), a micro-nano optical fiber sensor (4), an ion battery (5), a reflecting optical fiber (6), an optical fiber amplifier (7), a spectrometer (8), and a computer (9) to construct a reflective sensing optical path; wherein the micro-nano optical fiber sensor (4) is implanted inside the ion battery to be measured, and a micro-nano optical fiber coupler (4-1) coated with a nano-film of a material sensitive to ion concentration is fixed at the junction of the metal anode and the electrolyte in the lithium battery; the micro-nano optical fiber coupler (4-1) is formed by melting two optical fibers with a portion of the coating removed by an oxyhydrogen flame taper machine. The micro-nano optical fiber coupler (4-1) is made of a standard single-mode optical fiber cross-fused tapered, and the diameter of the uniform waist region is controlled at 3 to 10 μm, which can meet the large-scale evanescent field distribution required for higher sensitivity; the surface of the micro-nano optical fiber coupler (4-1) is covered with an ion-sensitive functional film (4-2), and the functional film (4-2) is composed of two layers, the first layer is a dry film impregnated with a chitosan solution diluted with acetic acid, and the second layer is a dense stacked film of MXene composite AuNPs, which can excite the surface plasmon resonance (SPR) phenomenon, thereby enhancing the detection sensitivity of the micro-nano optical fiber sensor (4) to ion concentration.

[0009] In one embodiment, the micro-nano fiber lithium battery in-situ detection scheme is as follows: a light source (1) provides a stable broadband optical signal, the optical signal passes through an optical fiber isolator (2) and an incident optical fiber (3) in sequence, is coupled into an incident end (4-3) of a micro-nano fiber sensor (4), and is transmitted to the micro-nano fiber region, is reflected back to the waist region of the micro-nano fiber coupler (4-1) by a reflective metal film (4-5), and is controlled by the optical fiber isolator (2) so that the optical signal is reflected only to an optical fiber amplifier (7). After optical signal loss compensation is completed, the optical signal is sent to a spectrometer (8), and the spectrometer (8) transmits the spectral information of the optical signal to a signal terminal, thereby realizing in-situ detection inside the ion battery.

[0010] In one embodiment, the light source (1) adopts a C+L band ASE broadband light source with a central wavelength of 1550 nm.

[0011] In one embodiment, the optical fiber amplifier (7) is an erbium-doped optical fiber amplification light source, which can provide amplification of a single-frequency input laser of 1525nm-1625nm, with a maximum output of 40W, and the amplifiable wavelength range is included in the wavelength range of the optical signal emitted by the broadband light source.

[0012] In one embodiment, the spectrometer (8) is an Ocean Optics small-volume infrared spectrometer with a detection wavelength range of 950-1650 nm, and the detectable wavelength range is included in the wavelength range of the light signal emitted by the broadband light source.

[0013] In one embodiment, the refractive index of the nanofilm of the material sensitive to ion concentration changes due to different adsorption degrees after adsorbing ions. The slight change in the refractive index will affect the evanescent field distribution between the core and cladding in the micro-nano optical fiber coupler, and the interference spectrum received by the spectrometer will fluctuate regularly, thereby realizing optical fiber sensing of ion concentration.

[0014] In one embodiment, the output spectral interference peak of the reflective optical path has an envelope characteristic, wherein the wavelength of the SPR absorption trough presented will produce significant periodic drift along with the fluctuation of ion concentration. By testing and calibrating the correspondence between the wavelength drift range and the actual battery capacity, in-situ detection of the battery health status can be achieved.

[0015] The present invention has at least the following beneficial effects:

[0016] 1. The micro-nano fiber optic sensor used in the present invention has the advantages of low cost, simple structure, high sensitivity, anti-electromagnetic interference, and corrosion resistance. The core of the sensor lies in the structure of the micro-nano fiber optic coupler modified with MXene composite gold nanoparticles (AuNPs), which can stimulate the surface plasmon resonance (SPR) phenomenon and further realize high-sensitivity sensing of refractive index based on the evanescent field principle, making the system simple in structure, high in sensitivity, and highly integrated.

[0017] 2. The present invention determines the drift range of the SPR absorption trough and combines it with the detected change in battery ion concentration to obtain a corresponding relationship between the two, thereby achieving in-situ detection of the battery health status. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural schematic diagram of an in-situ detection method for an SPR-type optical fiber ion battery based on MXene modification provided by the present invention.

[0019] Figure 2 This is a structural diagram of the micro-nano optical fiber sensor provided by the present invention.

[0020] Figure 3This is the reflection spectrum obtained after the micro-nano optical fiber sensor provided by the present invention is connected to the optical path.

[0021] In the figure: 1—light source, 2—fiber isolator, 3—incident fiber, 4—micro-nano fiber sensor, 4-1—micro-nano fiber coupler, 4-2—functionalized film, 4-3—incident end, 4-4—reflection end, 4-5—reflective metal film, 5—ion battery, 6—reflecting fiber, 7—fiber amplifier, 8—spectrometer, 9—computer. DETAILED DESCRIPTION

[0022] In-situ detection of batteries based on fiber optic sensing has been a research hotspot in recent years. This embodiment provides a method for in-situ detection of ion batteries using SPR-type fiber optic sensors modified with MXene composite gold nanoparticles (AuNPs). By implanting a micro-nano fiber optic sensor modified with MXene composite gold nanoparticles (AuNPs) into the battery, in-situ detection of the ion concentration inside the battery is achieved through reflective fiber optic sensing and spectral demodulation. In addition, relying on the characteristic that the wavelength of the SPR absorption trough in the reflection spectrum will produce significant periodic drift with fluctuations in ion concentration, the corresponding relationship between the wavelength drift range and the actual battery capacity can be determined, providing a powerful means for battery development and detection.

[0023] like Figure 1 As shown, an embodiment of the present invention provides an in-situ detection method of an SPR type optical fiber ion battery based on MXene modification, the system includes a light source (1), an optical fiber isolator (2), an incident optical fiber (3), a micro-nano optical fiber sensor (4), an ion battery (5), a reflecting optical fiber (6), an optical fiber amplifier (7), a spectrometer (8), and a computer (9). The structure of the micro-nano optical fiber sensor (4) is as follows Figure 2 As shown, it includes: a micro-nano fiber coupler (4-1), a functionalized film (4-2), an incident end (4-3), and a reflective metal film (4-5) coated at the end of the reflective end (4-4), wherein the micro-nano fiber coupler is made of two standard single-mode optical fibers with part of the coating removed and cross-fused tapered, and its uniform waist diameter is 8μm. The two original output ends are cut with a length difference of 5mm and a layer of metal reflective film is coated on the cut surface, and the two reflective arms on the coated side are the reflective ends (4-4). Finally, the ion concentration-sensitive functionalized film (4-2) is uniformly coated on the uniform waist area of the micro-nano fiber coupler (4-1), and the film thickness is 100nm.

[0024] Further, according to Figure 1The detection system layout connects the light source (1), the optical fiber isolator (2), the incident optical fiber (3), the micro-nano optical fiber sensor (4), the reflective optical fiber (6), the optical fiber amplifier (7), the spectrometer (8), and the computer (9) in sequence to build a reflective sensing optical path, and implants the micro-nano optical fiber sensor (4) into the ion battery (5), wherein the micro-nano optical fiber sensor (4) is fixed at the junction of the anode and the electrolyte of the ion battery (5) to ensure that the material nanofilm (4-2) can completely contact the electrolyte in the battery.

[0025] The above-mentioned ion concentration-sensitive functionalized film (4-2) consists of two layers. The first layer is a dried film impregnated with a chitosan solution diluted with acetic acid, which increases the surface roughness of the material and imparts carboxyl groups. The second layer is a dense laminated film of MXene composite AuNPs, which increases the specific surface area exposed to the environment. MXene not only enhances the ion binding efficiency as an electrode material, but also firmly composites AuNPs based on its own stability and multilayer structural characteristics. By stimulating the surface plasmon resonance (SPR) phenomenon, the wavelength response distance of the reflection spectrum can map the change law of ion concentration, thereby greatly improving the sensitivity of the optical fiber sensor, thereby enhancing the detection sensitivity of the micro-nano optical fiber sensor (4) to ion concentration. In addition, the functionalized film (4-2) provides a certain degree of mechanical strength to the uniform waist of the micro-nano optical fiber coupler (4-1), maintaining the life span and long-term stability of the micro-nano optical fiber sensor (4).

[0026] The following is an explanation of the in-situ detection method of the SPR-type fiber ion battery based on MXene modification:

[0027] The optical power signal output by the light source (1) is transmitted from the incident optical fiber (3) to the micro-nano optical fiber sensor (4), and passes through the uniform waist area of the micro-nano optical fiber coupler (4-1). Since the waist diameter reaches the micron level, the fiber core is too thin to constrain the total reflection propagation of light, and then the optical fiber cladding is used as the new "fiber core" and the outer background of the optical fiber is used as the new "cladding". The evanescent field excited between the fiber core and the cladding will induce the low-order mode in the optical fiber, and the low-order mode will cause mode interference with the base film of the single-mode optical fiber, thereby making the micro-nano optical fiber coupler The transmission spectrum of (4-1) shows a regular interference spectrum. After the transmitted light passes through the micro-nano fiber coupler (4-1), it is reflected by the reflective metal film (4-5) at the end of the reflective end (4-4). Furthermore, after the reflected light passes through the micro-nano fiber coupler (4-1), the optical signal is controlled by the optical fiber isolator (2) so that the optical signal is reflected only to the optical fiber amplifier (7). After the optical signal loss compensation is completed, the optical signal is sent to the spectrometer (8). Finally, the spectrum signal is processed by the computer (9) to realize the in-situ detection inside the lithium battery (1).

[0028] Preferably, the light source (1) adopts a C+L band ASE broadband light source with a central wavelength of 850 nm.

[0029] Preferably, the optical fiber amplifier (7) is an erbium-doped optical fiber amplification light source, which can provide amplification of a single-frequency input laser of 650 to 1650 nm, with a maximum output of 40 W, and the amplifiable wavelength range is included in the wavelength range of the optical signal emitted by the broadband light source.

[0030] Preferably, the spectrometer (8) is an Ocean Optics small-volume infrared spectrometer with a detection wavelength range of 650 to 1650 nm, and the detectable wavelength range is included in the wavelength range of the light signal emitted by the broadband light source.

[0031] The battery in-situ detection method described in this embodiment is specifically that after the device is connected, the initial spectrum of the ion battery (5) is first obtained, and its specific trough wavelength is defined as the minimum value of the working range λ_min; then the second stable charge and discharge cycle is performed, and the spectrum changes are monitored in real time during the charging stage. After the charging is completed, the multi-cycle spectrum data is baseline calibrated and noise elimination is performed, and by establishing a relative coordinate system with the initial trough as the reference origin, the wavelength drift of the specific trough of each cycle is calculated, and the wavelength value λ_max corresponding to the maximum drift Δλ_max is selected as the upper limit of the working range. Finally, [λ_min, λ_max] constitutes the spectral response judgment interval for normal battery operation, and the corresponding relationship between the wavelength drift interval and the actual battery capacity is calibrated by testing, so as to realize real-time monitoring of the characteristic absorption peak of the electrode material, thereby realizing in-situ detection of the battery health status; by eliminating the spectral data interference in the SEI film formation stage in the first charge and discharge cycle, the accuracy of the detection result is ensured.

Claims

1. A method for in-situ detection of SPR-type fiber ion batteries based on MXene modification, characterized by: The system includes a light source (1), an optical fiber isolator (2), an incident optical fiber (3), a micro-nano optical fiber sensor (4), an ion battery (5), a reflecting optical fiber (6), an optical fiber amplifier (7), a spectrometer (8), and a computer (9); The structure of the micro-nano optical fiber sensor (4) comprises: a micro-nano optical fiber coupler (4-1), a functionalized film (4-2), an incident end (4-3), a reflection end (4-4), an output end (4-5), and a reflective metal film (4-6) plated at the end of the reflection end (4-4). The in-situ detection method of an SPR-type optical fiber ion battery based on MXene modification is characterized in that: a light source (1) provides a stable broadband optical signal, and the signal passes through an optical fiber isolator (2), an incident optical fiber (3), a micro-nano optical fiber coupler (4-1), an incident end (4-3), and a reflection end (4-4) in sequence, and is reflected by a reflective metal film (4-6) and transmitted through the micro-nano optical fiber coupler (4-1), an output end (4-5), and a reflection optical fiber (6) to an optical fiber amplifier (7), a spectrometer (8), and then the data is processed by a computer (9).

2. The in-situ detection method of a MXene-modified SPR fiber ion battery according to claim 1, characterized in that: The micro-nano fiber coupler (4-1) is made by cross-melting and taper-drawing two standard single-mode optical fibers with part of the coating removed using an oxyhydrogen flame melting taper machine. The diameter of the uniform waist region of the micro-nano fiber coupler (4-1) is controlled to be 3 to 10 μm, which satisfies the large-proportion evanescent field distribution required for high sensitivity, can effectively shorten the ion transmission path, and reduce the risk of deformation of the electrode material during the charge and discharge process, thereby significantly improving the cycle stability and capacity retention rate of the battery. The surface of the micro-nano fiber coupler (4-1) is covered with a layer of ion-sensitive functional film (4-2), the refractive index of which increases with the increase of the ion concentration in the environment in which it is located. The functionalized film (4-2) consists of two layers. The first layer is a dried film impregnated with a chitosan solution diluted with acetic acid, which increases the surface roughness of the material and imparts carboxyl groups. The second layer is a dense laminated film of MXene composite AuNPs. MXene as an electrode material exhibits excellent long-term structural stability in an electrolyte environment. Its unique two-dimensional layered structure enables it to withstand the mechanical stress during battery charging and discharging, maintain structural integrity, and have good electrochemical stability. It can resist chemical corrosion and oxidation in the electrolyte, reduce dissolution or degradation in the electrolyte, and thus ensure the stability and reliability of the battery during long-term operation.

3. The in-situ detection method of a MXene-modified SPR fiber ion battery according to claim 1, characterized in that: The second layer of the functionalized film (4-2) is a dense laminated film of MXene composited with AuNPs. Based on the stability of MXene itself and the characteristics of the multi-layer structure, the AuNPs are firmly composited. By stimulating the surface plasmon resonance (SPR) phenomenon, the wavelength response distance of the reflection spectrum after Fourier filtering can map the variation law of ion concentration, thereby greatly improving the sensitivity of the optical fiber sensor; the reflective metal film (4-6) is a metal film with high reflectivity and wide spectral range coated on the reflection end (4-4) of the micro-nano optical fiber coupler (4-1) using a magnetron sputtering coating machine, so that the optical signal originally outputted is reflected back to the waist region and output end (4-5) of the micro-nano optical fiber coupler (4-1), and under the control of the optical fiber isolator (2), the optical signal is only reflected to the optical fiber amplifier (7). After completing the optical signal loss compensation, the optical signal is sent to the spectrometer (8), thereby realizing the detection of the reflected signal by the overall sensing system.

4. The in-situ detection method of a MXene-modified SPR fiber ion battery according to claim 1, characterized in that: The in-situ detection method specifically monitors the wavelength drift position of the SPR absorption trough presented after Fourier filtering reflection spectrum as the basis for determining the ion concentration sensing inside the ion battery (5); the micro-nano optical fiber sensor (4) is fixed at the junction of the anode and the electrolyte of the ion battery (5); during the battery's electrical cycle, the wavelength of the SPR absorption trough will produce significant periodic drift accompanied by ion concentration fluctuations, and the corresponding relationship between the wavelength drift range and the actual battery capacity is tested and calibrated, thereby realizing in-situ detection of the battery health status.

5. The in-situ detection method of a MXene-modified SPR fiber ion battery according to claim 1, characterized in that: The light source (1) is a spontaneous emission amplified light source centered in the visible light band, with an output spectrum center wavelength of 850 nm. It can provide high spectral density output within the wavelength range of 650 to 1100 nm, covering the wavelength range of the dense interference region of the reflection spectrum of the micro-nano optical fiber sensor (4). The optical fiber amplifier (7) is an erbium-doped optical fiber amplified light source with a maximum output of 40 W, while ensuring extremely low intensity noise and phase noise of the output laser. The spectrometer (8) is a near-infrared spectrometer with a detection wavelength range of 650 to 1650 nm.

Images