A micro-nano fiber lithium battery in-situ detection device and method based on spatial optical communication

Abstract

The application is suitable for the field of optical fiber sensor and the field of in-situ detection of batteries, and provides a micro-nano optical fiber lithium battery in-situ detection device and method based on space optical communication. The battery in-situ detection device is that a MF-TFG optical fiber probe is implanted into a lithium battery, based on the principle that a 45-degree inclined fiber grating simultaneously receives and radiates a sensing light signal, so that the sensing light signal is received by a CCD detector after collimation by a cylindrical lens and remodeling by a convex lens group in the internal space of a battery detection box, and in-situ detection is performed on the temperature, pressure and ion concentration in the lithium battery to be detected according to the spectrum drift phenomenon. The embodiment provided by the application can realize non-contact in-situ detection of the battery, and has the advantages of high integration and real-time detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fiber sensors and the field of in-situ detection of batteries, and in particular to a micro-nano fiber lithium battery in-situ detection device and method based on spatial optical communication. BACKGROUND

[0002] Lithium batteries have developed rapidly due to their high energy density, long service life, and high power density. However, the problem of thermal runaway of batteries is quite serious. This is a series of complex "chain side reactions" inside the lithium battery, which causes the internal temperature of the battery to rise rapidly and cause fire and explosion. Conventional battery detection methods, such as battery impedance detection, gas testing, BMS, thermal runaway test machine, etc., all analyze the parameters to be measured by applying test conditions to the battery to evaluate the health and life of the battery. These testing methods ensure measurement accuracy, but cannot detect batteries in real time while they are in operation, which is not conducive to monitoring and preventing thermal runaway problems inside the battery. At present, the widespread application of fiber optic sensing provides a solution for in-situ detection of lithium batteries. Implantable fiber optic sensors, as a new technology for battery detection, have the advantages of high sensitivity, electromagnetic interference resistance, and stable life, making them suitable for use in harsh environments such as high pressure, high temperature, and flammable and explosive environments, which is difficult to achieve with traditional battery detection equipment.

[0003] Fiber optic sensors are small in size, flexible in shape, suitable for standard manufacturing techniques for mass production, and can simultaneously monitor temperature, pressure, and ion concentration in multiple locations of a battery with one fiber. It can be seen that implantable fiber optic sensors are a hot research topic in the field of in-situ detection of batteries, but the tail fiber transmission connection of fiber optic sensors limits their application scope. Correspondingly, non-contact detection has become a better solution. Therefore, exploring a non-contact fiber battery in-situ detection device is of great significance to the development of lithium batteries. SUMMARY

[0004] The present application aims to solve the demand for non-contact fiber in-situ detection technology for lithium batteries, and provides a micro-nano fiber lithium battery in-situ detection device and method based on spatial optical communication. The MF-TFG fiber probe is implanted in the lithium battery in the shape of an inverted "U", and based on the principle of simultaneously receiving and radiating sensing optical signals by a 45° inclined fiber grating, the sensing optical signals are received by a CCD detector after collimation by a cylindrical lens and reshaping by a convex lens group in the internal space of the battery detection box. The temperature, pressure, and ion concentration of the lithium battery to be measured are detected in-situ based on the spectral shift phenomenon.

[0005] The technical scheme adopted by the present application is: a micro-nano optical fiber lithium battery in-situ detection device based on spatial optical communication, which is characterized by comprising: a lithium battery, an MF-TFG optical fiber probe, an optical communication window, a battery detection box, and a signal terminal; the MF-TFG optical fiber probe structure comprises: a micro-nano optical fiber, a 45° inclined fiber grating, a material nano film, and a metal reflective film, wherein the micro-nano optical fiber end is fixed at the junction of the metal anode and the electrolyte in the lithium battery, the 45° inclined fiber grating is fixed in the lithium battery packaging shell, and the grating area is aligned with the position of the optical communication window; the battery detection box comprises: a battery clamp, a broadband light source, a single-mode optical fiber jumper, an optical collimator, a beam splitter, a cylindrical lens, a first convex lens, a second convex lens, and a CCD detector, the two convex lenses and the CCD detector are coaxially arranged and the axial direction is perpendicular to the radiation direction of the optical fiber collimator, the beam splitter is placed at the center of the two light paths and the normal line of the plate surface is fixed to coincide with the angle bisector of the two paths;

[0006] Further, the micro-nano optical fiber lithium battery in-situ detection scheme is: the lithium battery is fixed by the battery clamp, the optical communication window is aligned with the frame of the cylindrical lens, the broadband light signal is generated by the broadband light source in the battery detection box, the polarization controller converts it into s-polarized light, the collimated light passes through the side of the beam splitter to the cylindrical lens after collimation by the optical fiber collimator, then it is captured by the 45° inclined fiber grating through the optical communication window outside the battery detection box, the s-polarized light is coupled into the optical fiber probe and transmitted to the micro-nano optical fiber area, the sensing signal is reflected by the metal film, the s-polarized light signal is separated by the 45° inclined fiber grating and radiated at different angles according to the wavelength, the sensing light signal is collimated by the optical communication window and the cylindrical lens, reflected at 90° from the other side of the beam splitter to the first convex lens and the second convex lens, the two shape and focus the sensing light signal and it is received by the CCD detector, the CCD transmits the spectral information of the light signal to the signal terminal, realizing non-contact in-situ detection of the lithium battery.

[0007] Further, the broadband light source adopts a C+L band ASE broadband light source with a center wavelength of 1550 nm.

[0008] Further, in the battery detection box, the spatial light propagation trajectory presents an inverted "T" shape under the action of the beam splitter; the sensing light forms a series of light beams with different scattering angles under the scattering action of the 45° inclined fiber grating, the light beams are collimated in the transverse direction through the cylindrical lens, so that the light beams of different wavelengths are in the same plane, the beam splitter reflects the light beams to change the propagation trajectory angle and align the convex lens group, the light beams are collimated by the first convex lens, so that all the light beams remain parallel when passing through, and then the light beams are shaped and focused by the second convex lens to form a light spot.

[0009] Further, the pixel of the CCD detector is less than 10 μm, and the detectable wavelength range is included in the wavelength range of the light signal emitted by the broadband light source.

[0010] Further, the micro-nano fiber lithium battery in-situ detection has the characteristics of convenient and real-time detection, without the need of complex connection between the to-be-detected lithium battery and the battery detection box, and the in-situ detection of the battery can be performed only by fixing the battery clamp, and the lithium battery of various sizes can be adapted by adjusting the distance between the clamps, thereby meeting the diversity of the in-situ detection device of the battery.

[0011] The present application has the following beneficial effects relative to the prior art:

[0012] 1. The micro-nano fiber 45° inclined fiber grating used in the present application is used as a fiber probe, has high integration and can detect multiple parameters such as temperature, pressure and lithium ion concentration at the same time, and can reduce the manufacturing cost of the sensor.

[0013] 2. The design method of the present application interfaces the optical signal with the internal sensor of the battery through space optical communication, breaks the need for physical contact of the optical fiber, and expands the optical fiber sensing application which depends on a long tail fiber. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a structure schematic view of a micro-nano fiber lithium battery in-situ detection device and method based on space optical communication according to an embodiment of the present application.

[0015] Figure 2 It is a working principle diagram of the MF-TFG fiber probe according to an embodiment of the present application.

[0016] Figure 3 It is a lithium ion concentration detection spectrum response diagram according to an embodiment of the present application.

[0017] Figure 4 It is a lithium ion concentration response data fitting result diagram according to an embodiment of the present application.

[0018] In the figure: 1 - lithium battery, 2 - MF-TFG fiber probe, 2-1 - micro-nano fiber, 2-2 - 45° inclined fiber grating, 2-3 - material nano film, 2-4 - metal reflective film, 3 - optical communication window, 4 - battery detection box, 4-1 - battery clamp, 4-2 - broadband light source, 4-3 - single-mode fiber jumper, 4-4 - optical collimator, 4-5 - beam splitter, 4-6 - cylindrical lens, 4-7 - first convex lens, 4-8 - second convex lens, 4-9 - CCD detector, 5 - signal terminal. DETAILED DESCRIPTION

[0019] The purpose of the present application is to provide a micro-nano fiber lithium battery in-situ detection device and method based on space communication, which can realize non-contact internal in-situ detection of the lithium battery.

[0020] In order to make the above objectives, technical solutions and advantages of the present application clearer, the following will further describe the present application with reference to the accompanying drawings of the embodiments of the present application. However, the embodiments of the present application and the protection scope are not limited thereto, and any substantially same implementation belongs to the protection scope of the present application.

[0021] As shown in Figure 1 , the embodiment of the present application provides a micro-nano fiber lithium battery in-situ detection device and method based on spatial optical communication. The device comprises a lithium battery (1), an MF-TFG optical fiber probe (2), an optical communication window (3), a battery detection box (4), and a signal terminal (5). The structure of the MF-TFG optical fiber probe (2) is shown in Figure 2 , which comprises a micro-nano fiber (2-1), a 45° inclined fiber grating (2-2), a material nano film (2-3), and a metal reflective film (2-4). The structure of the battery detection box (4) comprises a battery clamp (4-1), a broadband light source (4-2), a single-mode fiber jumper (4-3), an optical collimator (4-4), a beam splitter (4-5), a cylindrical lens (4-6), a first convex lens (4-7), a second convex lens (4-8), and a CCD detector (4-9).

[0022] Further, according to the detection device layout Figure 1 , the broadband light source (4-2), the single-mode fiber jumper (4-3), and the optical collimator (4-4) are connected in sequence. The first convex lens (4-7), the second convex lens (4-8), and the CCD detector (4-9) are coaxially placed and the axial direction is perpendicular to the radiation direction of the optical collimator (4-4). The beam splitter (4-5) is placed at the center of the two light paths and the plate surface perpendicular line is fixed to coincide with the two angle bisectors. The lithium battery (1) is fixed to the side of the battery detection box (4) through the battery clamp (4-1), and the optical communication window (3) is aligned with the outline of the cylindrical lens (4-6) by adjusting the distance between the battery clamps (4-1).

[0023] Further, according to the detection device layout Figure 2The MF-TFG optical fiber probe (2) is made of a standard single-mode optical fiber. Firstly, a 45° inclined fiber grating (2-2) is processed and engraved at one end of the optical fiber by a femtosecond laser. The grating pitch is adjusted so that the interference loss peak of the fundamental mode in the transmission spectrum is located at a wavelength of 1550 nm. Secondly, the coating layer is removed from the other end of the optical fiber, and a micro-nano optical fiber (2-1) with a diameter of 8 μm is prepared by a fused taper method. Finally, a silver metal reflective film (2-4) is plated on the end face of the micro-nano optical fiber (2-1) by using a magnetron sputtering device, the direction of the optical signal propagation is changed, and a reflective probe is formed. The micro-nano optical fiber (2-1) leaks light due to its small diameter, thereby exciting a large proportion of evanescent field on the surface of the optical fiber, resulting in that the transmission mode in the optical fiber is controlled by the background refractive index. A lithium ion sensitive material nanofilm (2-3) is covered on the surface of the micro-nano region of the micro-nano optical fiber (2-1). The refractive index of the material changes due to the difference in the adsorbed lithium ion concentration, thereby enhancing the sensitivity of the MF-TFG optical fiber probe (2) to the lithium ion concentration. The material nanofilm (2-3) is a nanofiber film of crown ether functionalized graphene oxide composite chitosan combined with polyvinyl alcohol (GO-CE-CS-PVA).

[0024] Further, the MF-TFG optical fiber probe (2) is implanted in the inside of the lithium battery (1) in an inverted “U” shape. The micro-nano optical fiber (2-1) is fixed at the center of the interface between the metal anode and the electrolyte of the lithium battery (1) as a sensing part. The 45° inclined fiber grating (2-2) is fixed in the packaging protective layer of the lithium battery (1) as a signal transmission end. An optical communication window (3) is processed outside the grating region of the packaging layer of the lithium battery (1), so that the overall lithium battery retains the original sealed environment.

[0025] The micro-nano optical fiber lithium battery in-situ detection device and method based on spatial optical communication will be described below.

[0026] The micro-nano optical fiber lithium battery in-situ detection device based on spatial optical communication comprises an optical fiber sensing system. A stable broadband light signal is provided by a broadband light source (4-2) in the sensing system. The signal is radiated by an optical collimator (4-4) through a monomode optical fiber jumper (4-3), a beam splitter (4-5), a cylindrical lens (4-6), and an optical communication window (3) in sequence. The signal is received and coupled by the 45° inclined fiber grating (2-2) in the MF-TFG optical fiber probe (2). The sensing light signal is converted into a sensing light signal in the micro-nano optical fiber (2-1) region by sensing and is reflected by the metal reflective film (2-4). The signal is radiated by the 45° inclined fiber grating (2-2) through the optical communication window (3), is collimated by the cylindrical lens (4-6) in free space in sequence, is refracted by the beam splitter (4-5), is remolded and focused by a first convex lens (4-7) and a second convex lens (4-8), and is received by a CCD detector (4-9). Finally, the spectral signal is processed by a signal terminal (5) to realize in-situ detection of the lithium battery (1).

[0027] Preferably, the broadband light source (4-2) adopts a C+L band ASE broadband light source with a center wavelength of 1550nm.

[0028] Preferably, the CCD detector (4-9) is a CinCam CMOS beam analyzer (CMOS-1202-IR) with a wavelength range of 1470nm to 1605nm, a pixel size of 5.3μm×5.3μm, and the detectable wavelength range is included in the wavelength range of the light signal emitted by the broadband light source (4-2).

[0029] The in-situ lithium battery detection method described in this embodiment specifically involves applying parameters such as temperature, pressure, and lithium-ion concentration to a micro / nano fiber (2-1) and a 45° tilted fiber grating (2-2). Due to differences in position and function, changes in the transmission mode within the fiber are induced, leading to spectral drift for sensing. Particular attention is paid to the wavelength shifts corresponding to the cladding mode of the micro / nano fiber (2-1) and the core mode and cladding cutoff mode of the 45° tilted fiber grating (2-2). The nanofilm material (2-3) enhances the lithium-ion detection of the micro / nano fiber. The lithium ion concentration only affects the cladding mode in the micro-nano fiber (2-1). The pressure deformation has a negligible effect on the micro-nano fiber (2-1) located in the center of the lithium battery (1), but it will cause deformation of the 45° tilted fiber grating (2-2) in the lithium battery (1) encapsulation shell, thus affecting the core mode and cladding cutoff mode in the 45° tilted fiber grating (2-2). The fiber optic sensors all have a linear response to temperature changes, so temperature can simultaneously affect the cladding mode, core mode and cladding cutoff mode.

[0030] This embodiment demonstrates the testing of lithium ion concentration within a lithium battery (1) using the in-situ detection device: the MF-TFG fiber probe (2) is placed in lithium-ion electrolytes of different concentrations, and the test results are as follows. Figure 3 As shown, its spectral information is received by a CCD detector (4-9), and the spectral morphology is the superposition of the reflection spectra of a 45° tilted fiber grating (2-2) cascaded with a micro / nano fiber (2-1). When the lithium-ion concentration changes, attention is paid to three loss interference valleys in the spectrum: the cutoff mode and the core mode in the 45° tilted fiber grating (2-2) at the interference valley Dip. end With Dip core And the significant interference valley Dip in micro / nano fiber (2-1) A When the lithium ion concentration in the environment where the MF-TFG fiber probe (2) is located increases, Dip A Significant redshift, while Dip end With Dip core Since there is no drift tendency, the lithium-ion concentration can theoretically be demodulated based on the location and distance of the loss interference valley.

[0031] Further, in order to verify the reliability of the actual response of the lithium battery in-situ detection device, the lithium ion concentration test results are extracted and linearly fitted in this embodiment, and the results are shown in FIG. 8. In the range of 0-1×10 Figure 4 -4 mol / L, the Dip -3 -4 mol / L, the Dip end The distance of red shift with concentration is logarithmically fitted, and the linearity R 2 value reaches 0.9926. This embodiment verifies the applicability of the micro-nano fiber lithium battery in-situ detection device and method based on spatial optical communication.

Claims

1. A micro / nano fiber optic lithium battery in-situ detection device based on space optical communication, characterized in that: The micro-nano fiber optic lithium battery in-situ detection device includes: a lithium battery (1), an MF-TFG fiber optic probe (2), an optical communication window (3), a battery detection box (4), and a signal terminal (5); The MF-TFG fiber probe (2) structure comprises: micro / nano fiber (2-1), a 45° tilted fiber grating (2-2), a material nanofilm (2-3), and a metal reflective film (2-4). The MF-TFG fiber probe (2) is made from a standard single-mode fiber. First, a 45° tilted fiber grating (2-2) is fabricated at one end of the fiber using a femtosecond laser. The grating pitch is adjusted so that the fundamental mode interference loss peak in its transmission spectrum is located at a wavelength of 1550 nm. Then, the coating layer is removed from the other end of the fiber, and a micro / nano fiber (2-1) with a diameter of 8 μm is fabricated using the fused taper method. Finally... A silver metal reflective film (2-4) is deposited on the end face of a micro-nano optical fiber (2-1) using magnetron sputtering equipment to change the direction of optical signal propagation and form a reflective probe; a lithium-ion sensitive material nanofilm (2-3) is coated on the surface of the micro-nano region of the micro-nano optical fiber (2-1); the material nanofilm (2-3) is a crown ether functionalized graphene oxide composite chitosan combined with polyvinyl chloride (GO-CE-CS-PVA) nanofiber film; the material nanofilm (2-3) is a crown ether functionalized graphene oxide composite chitosan combined with polyvinyl chloride (GO-CE-CS-PVA) nanofiber film; The battery testing box (4) structure includes: a battery clamp (4-1), a broadband light source (4-2), a single-mode fiber optic patch cord (4-3), an optical collimator (4-4), a beam splitter (4-5), a cylindrical lens (4-6), a first convex lens (4-7), a second convex lens (4-8), and a CCD detector (4-9). A broadband light source (4-2) provides a stable broadband optical signal. The signal is radiated by the optical collimator (4-4) through the single-mode fiber jumper (4-3) and passes through the beam splitter (4-5), cylindrical lens (4-6) and light-transmitting port (3) respectively. It is received and coupled by the 45° tilted fiber grating (2-2) in the MF-TFG fiber probe (2). The optical signal is converted into a sensing optical signal by the sensing effect in the micro-nano fiber (2-1) region and reflected by the metal reflective film (2-4). It is then radiated by the 45° tilted fiber grating (2-2) through the optical communication window (3). In free space, it is collimated by the cylindrical lens (4-6), refracted by the beam splitter (4-5), and refocused by the first convex lens (4-7) and the second convex lens (4-8). It is then received by the CCD detector (4-9) and finally processed by the signal terminal (5) to realize the in-situ detection inside the lithium battery (1).

2. The in-situ detection device for micro / nano fiber optic lithium batteries based on space optical communication according to claim 1, characterized in that: The MF-TFG fiber probe (2) is implanted in the lithium battery (1) in an inverted "U" shape. The micro-nano fiber (2-1) is fixed at the interface between the metal anode and the electrolyte of the lithium battery (1) as a sensing part. The 45° tilted fiber grating (2-2) is fixed in the side encapsulation protective layer of the lithium battery (1) as a signal transmission end. A glass optical communication window (3) is processed on the outside of the encapsulation layer of the lithium battery (1) at the grating area so that the lithium battery retains its original sealed environment.

3. The in-situ detection device for micro / nano fiber optic lithium batteries based on space optical communication according to claim 1, characterized in that: The broadband light source (4-2) is a C+L band ASE broadband light source with an output spectrum center wavelength of 1550nm and a bandwidth range of 100nm, covering the wavelength range of the dense interference region of the micro-nano fiber (2-1) reflection spectrum.

4. A method for in-situ detection of lithium batteries using micro / nano optical fibers based on space optical communication, the method being used in the in-situ detection device for lithium batteries using micro / nano optical fibers based on space optical communication as described in claim 1, characterized in that: The sensing light signal is received by the CCD detector (4-9), and the characteristic wavelength drift data caused by inter-mode interference is transmitted to the signal terminal (5). The mode includes: the cladding mode of the micro-nano fiber (2-1), the core mode and the cladding cutoff mode of the 45° tilted fiber grating (2-2). Each parameter acts on the micro-nano fiber (2-1) and the 45° tilted fiber grating (2-2). Due to the difference in position and function, the change in the transmission mode in the fiber is induced, which causes the characteristic wavelength drift for sensing. Among them, the lithium ion concentration affects the cladding mode. The pressure applied to the lithium battery (1) encapsulation shell squeezes the 45° tilted fiber grating (2-2) to produce deformation, which affects the core mode and the cladding cutoff mode. The temperature simultaneously affects the cladding mode, the core mode and the cladding cutoff mode.

5. The in-situ detection method for micro / nano fiber optic lithium batteries based on space optical communication according to claim 4, characterized in that: The lithium battery (1) implanted in the MF-TFG fiber optic probe (2) is fixed by the battery clamp (4-1) so that the optical communication window (3) is strictly aligned with the contour of the cylindrical lens (4-6) to avoid interference of the sensing optical signal caused by the gap, and to realize the spatial communication transmission of the optical signal.

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