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

Abstract

The invention is suitable for the field of optical fiber sensors and the field of battery in-situ detection, and provides a micro-nano optical fiber lithium battery in-situ detection device and method based on spatial optical communication, and the battery in-situ detection device is characterized in that an MF-TFG optical fiber probe is implanted into a lithium battery, and based on the principle that a 45-degree inclined optical fiber grating receives and radiates sensing optical signals at the same time, the optical fiber probe is embedded into the lithium battery; a sensing light signal is received by the CCD detector after being collimated by the cylindrical lens and remodeled by the convex lens group in the internal space of the battery detection box, and in-situ detection is carried out on the temperature, the pressure and the ion concentration in the lithium battery to be detected according to a spectrum drift phenomenon. The embodiment provided by the invention can realize non-contact in-situ detection of the battery, and has the advantages of high integration level, detection at any time and the like.

Description

Technical Field

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

[0002] Lithium batteries have developed rapidly due to their advantages such as high energy density, long service life and high power density. However, the thermal runaway problem of batteries is relatively serious. This is a series of complex "chain side reactions" inside lithium batteries, which causes the internal temperature of the battery to rise rapidly and cause fire and explosion. Conventional battery testing methods include battery impedance testing, gas testing, BMS, thermal runaway testers, etc., all of which assess the healthy life of the battery by applying test conditions to the battery and analyzing the parameters to be tested. These test methods ensure measurement accuracy, but cannot perform real-time detection of batteries in working state, 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. As an emerging technology for battery detection, implantable fiber optic sensors have significant advantages such as high sensitivity, anti-electromagnetic interference, and stable life, which enables them to be used in harsh environments such as high pressure and high temperature or flammable and explosive environments, which is difficult to achieve in traditional battery testing equipment.

[0003] Fiber optic sensors are small in size and flexible in shape, suitable for standard manufacturing technology for mass production, and can use one optical fiber to simultaneously monitor multiple key parameters such as temperature, pressure, and ion concentration at multiple locations in the battery. It can be seen that the research on implantable fiber optic sensors in the field of in-situ battery detection is quite hot, but the fiber pigtail transmission connection of fiber optic sensors limits its application scope. Correspondingly, non-contact detection has become a better solution. Therefore, exploring a non-contact fiber optic battery in-situ detection device is of great significance to the development of lithium batteries. Summary of the invention

[0004] The purpose of the present invention is to solve the needs of lithium batteries in non-contact optical fiber in-situ detection technology, and to provide a micro-nano optical fiber lithium battery in-situ detection device and method based on spatial optical communication. The MF-TFG optical fiber probe is implanted into the lithium battery in the shape of an inverted "U" shape, and based on the principle of 45° inclined optical fiber grating simultaneously receiving and radiating sensing light signals, the sensing light signal is collimated by a cylindrical lens and reshaped by a convex lens group in the internal space of the battery detection box and then received by a CCD detector. Based on the spectral drift phenomenon, the temperature, pressure, ion concentration and other parameters inside the lithium battery to be tested are detected in situ.

[0005] The technical solution adopted by the present invention 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 includes: a micro-nano optical fiber, a 45° tilted optical 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° tilted optical fiber grating is fixed in the lithium battery packaging shell, and the grating area is aligned with the optical communication window position; the battery detection box contains: a battery fixture, a broadband light source, a single-mode optical fiber jumper, an optical collimator, a spectroscope, a cylindrical lens, a first convex lens, a second convex lens, and a CCD detector, the two convex lenses are coaxially placed with the CCD detector and the axial direction is perpendicular to the radiation direction of the optical fiber collimator, the spectroscope is placed at the orthocenter position of the two optical paths and its plate normal is fixed to coincide with the two-path angular dividing line;

[0006] Furthermore, the micro-nano optical fiber lithium battery in-situ detection scheme is: fix the lithium battery with a battery clamp, align the optical communication window with the cylindrical lens frame, generate a broadband light signal by the broadband light source in the battery detection box, convert it into s-polarized light by the polarization controller, collimate it by the optical fiber collimator, transmit it to the cylindrical lens through one side of the spectroscope, and then capture it by the 45° tilted optical fiber grating outside the battery detection box through the optical communication window, couple the s-polarized light into the optical fiber probe and transmit it to the micro-nano optical fiber area, the metal film reflects the sensing signal, separates the s-polarized light signal by the 45° tilted optical fiber grating and radiates it at different angles according to the wavelength, collimates it through the optical communication window and the cylindrical lens, and reflects it from the other side of the spectroscope at a 90° inclination to the first convex lens and the second convex lens, which shape and focus the sensing light signal and are received by the CCD detector, and the CCD transmits the spectral information of the light signal to the signal terminal, thereby realizing non-contact in-situ detection inside the lithium battery.

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

[0008] Furthermore, 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, and the light beams are collimated laterally through the cylindrical lens so that the light beams of each wavelength are in the same plane. The light beams are reflected by the beam splitter to change the angle of the light beam propagation trajectory and align with the convex lens group. The light beams are collimated by the first convex lens so that all 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] Furthermore, the pixel size of the CCD detector is smaller 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] Furthermore, the micro-nano optical fiber lithium battery in-situ detection is convenient and can be detected at any time. There is no need to make a complicated connection between the lithium battery to be tested and the battery detection box. The battery can be detected in-situ only by fixing it with a battery clamp, and the clamp spacing can be adjusted to adapt to lithium batteries of various sizes and types, which meets the diversity of battery in-situ detection devices.

[0011] The present invention has the following beneficial effects compared with the prior art:

[0012] 1. The present invention adopts a micro-nano optical fiber cascade 45° tilted optical fiber Bragg grating as an optical fiber probe, which has a high degree of integration and can simultaneously detect multiple parameters such as temperature, pressure and lithium ion concentration, thereby reducing the manufacturing cost of the sensor.

[0013] 2. The design method of the present invention interfaces the optical signal with the internal sensor of the battery through spatial optical communication, breaking the need for physical contact of the optical fiber and expanding the application of optical fiber sensing that relies on longer pigtails. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0017] Figure 4 This is a graph showing the fitting results of lithium ion concentration response data according to an embodiment of the present invention.

[0018] In the figure: 1—lithium battery, 2—MF-TFG optical fiber probe, 2-1—micro-nano optical fiber, 2-2—45° tilted optical fiber Bragg grating, 2-3—material nanofilm, 2-4—metal reflective film, 3—optical communication window, 4—battery detection box, 4-1—battery fixture, 4-2—broadband light source, 4-3—single-mode optical 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 invention is to provide a micro-nano optical fiber lithium battery in-situ detection device and method based on space communication, which can realize non-contact internal in-situ detection of lithium batteries.

[0020] In order to make the above-mentioned objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the drawings in the embodiments of the present invention, but the embodiments and protection scope of the present invention are not limited thereto, and all substantially the same embodiments of the present invention belong to the protection scope of the present invention.

[0021] like Figure 1 As shown, an embodiment of the present invention provides a micro-nano optical fiber lithium battery in-situ detection device and method based on spatial optical communication, the device comprising 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 as follows: Figure 2 As shown, it includes: micro-nano optical fiber (2-1), 45° tilted optical fiber grating (2-2), material nano film (2-3) and metal reflective film (2-4). The battery detection box (4) structure includes: battery fixture (4-1), broadband light source (4-2), single-mode optical fiber jumper (4-3), light collimator (4-4), spectroscope (4-5), cylindrical lens (4-6), first convex lens (4-7), second convex lens (4-8) and CCD detector (4-9).

[0022] Further, according to Figure 1 The layout of the detection device connects the broadband light source (4-2), the single-mode fiber jumper (4-3) and the light collimator (4-4) 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 light collimator (4-4), and the beam splitter (4-5) is placed at the orthocenter position of the two light paths and fixed so that the vertical line of the plate coincides with the angle dividing line of the two paths. The lithium battery (1) needs to be fixed to the side of the battery detection box (4) by the battery fixture (4-1), and the optical communication window (3) is aligned with the outline of the cylindrical lens (4-6) by adjusting the spacing of the battery fixture (4-1).

[0023] Further, according to Figure 2The MF-TFG optical fiber probe (2) is made of a standard single-mode optical fiber. First, a 45° tilted optical fiber grating (2-2) is processed and written on one end of the optical fiber by a femtosecond laser, and the grating pitch is adjusted so that the fundamental mode interference loss peak in the transmission spectrum is located at a wavelength of 1550nm. Secondly, the coating layer at the other end of the optical fiber is removed and a fused taper method is used to prepare a micro-nano optical fiber (2-1) with a diameter of 8μm. Finally, a layer of silver metal reflective film (2-4) is plated on the end face of the micro-nano optical fiber (2-1) by a magnetron sputtering device to change the propagation direction of the optical signal to form a reflective probe. The micro-nano optical fiber (2-1) is a kind of optical fiber with a diameter of 8μm. The fiber (2-1) has light leakage due to its small diameter, thereby exciting a large proportion of evanescent field on the surface of the fiber, causing the transmission mode in the fiber to be regulated by the background refractive index. The surface of the micro-nano region of the micro-nano optical fiber (2-1) is covered with a layer of lithium ion sensitive material nanofilm (2-3), and the refractive index of the material changes due to the difference in the concentration of adsorbed lithium ions, 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 membrane of crown ether functionalized graphene oxide composite chitosan combined with polychloroethanol (GO-CE-CS-PVA).

[0024] Furthermore, the MF-TFG optical fiber probe (2) is implanted in the shape of an inverted "U" inside the lithium battery (1) to be tested, wherein 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, and the 45° inclined optical fiber grating (2-2) is fixed in the packaging protective layer of the lithium battery (1) as a signal transmission end, and an optical communication window (3) is processed outside the packaging layer of the lithium battery (1) at the gate area, so that the entire 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 are 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, wherein a broadband light source (4-2) provides a stable broadband optical signal, and the signal is radiated by an optical collimator (4-4) through a single-mode optical fiber jumper (4-3), respectively passes through a beam splitter (4-5), a cylindrical lens (4-6) and an optical communication window (3), and is received and coupled by a 45° inclined optical fiber grating (2-2) in an MF-TFG optical fiber probe (2). The sensing optical signal is transmitted through the micro-nano optical fiber ( The light in the area 2-1) is converted into a sensing light signal by the sensing action and reflected by the metal reflective film (2-4), and then radiated by the 45° inclined fiber grating (2-2) through the optical communication window (3), and is sequentially collimated by the cylindrical lens (4-6), refracted by the beam splitter (4-5), reshaped and focused by the first convex lens (4-7) and the second convex lens (4-8) in free space, and is then received by the CCD detector (4-9), and finally the spectral signal is processed by the signal terminal (5) to realize the in-situ detection inside the lithium battery (1).

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

[0028] Preferably, the CCD detector (4-9) adopts 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 a detectable wavelength range included in the wavelength range of the light signal emitted by the broadband light source (4-2).

[0029] The lithium battery in-situ detection method described in this embodiment is specifically to act on the micro-nano optical fiber (2-1) and the 45° tilted optical fiber grating (2-2) through the temperature, pressure and lithium ion concentration parameters. Due to the difference in position and function, the change of the transmission mode in the optical fiber is induced to cause the spectral drift for sensing, and special attention is paid to the migration of the wavelengths corresponding to the cladding mode of the micro-nano optical fiber (2-1), the core mode of the 45° tilted optical fiber grating (2-2) and the cladding cutoff mode; wherein the material nano film (2-3) can enhance the lithium ion of the micro-nano optical fiber. The optical fiber (2-1) responds to the lithium ion concentration, so the lithium ion concentration only affects the cladding mode in the micro-nano optical fiber (2-1); the pressure deformation has a negligible effect on the micro-nano optical fiber (2-1) located in the center of the lithium battery (1), but will squeeze and deform the 45° tilted optical fiber Bragg grating (2-2) in the packaging shell of the lithium battery (1), thereby affecting the core mode and cladding cut-off mode in the 45° tilted optical fiber Bragg grating (2-2); the optical fiber sensor has a linear response to temperature changes, so the temperature can affect the cladding mode, core mode and cladding cut-off mode at the same time.

[0030] In this embodiment, the lithium battery in-situ detection device is used to test the lithium ion concentration in the lithium battery (1): the MF-TFG optical fiber probe (2) is placed in lithium ion electrolytes with different concentrations. The test results are as follows: Figure 3 As shown, its spectral information is received by the CCD detector (4-9). The spectral morphology is the superposition of the reflection spectra of the 45° tilted fiber Bragg grating (2-2) cascaded micro-nano optical fiber (2-1). When the lithium ion concentration changes, the three loss interference valleys of the spectrum are concerned: the interference valley Dip between the cutoff mode and the core mode in the 45° tilted fiber Bragg grating (2-2) end With Dip core , and the significant interference valley Dip of micro-nano optical fiber (2-1) A ; When the lithium ion concentration in the environment of the MF-TFG optical fiber probe (2) increases, Dip A Obviously red shift, and Dip end With Dip core There is no drift tendency, so theoretically the lithium ion concentration can be demodulated based on the position distance of the loss interference valley.

[0031] Furthermore, in order to verify the reliability of the actual response of the lithium battery in-situ detection device, this embodiment extracts and processes the above lithium ion concentration test results and performs linear fitting. The results are as follows: Figure 4 As shown, in the range of 0 to 1×10 -3 Within the concentration range of M, Dip end The distance of red shift with concentration was fitted logarithmically, and the linearity R 2 The value reaches 0.9926. This embodiment formally demonstrates the applicability of the proposed micro-nano optical fiber lithium battery in-situ detection device and method based on spatial optical communication.

Claims

1. A micro-nano optical fiber lithium battery in-situ detection device and method based on spatial optical communication, characterized in that: The micro-nano optical fiber lithium battery in-situ detection 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) includes: a micro-nano optical fiber (2-1), a 45° tilted optical fiber grating (2-2), a material nano film (2-3) and a metal reflective film (2-4); The battery detection box (4) structure includes: a battery fixture (4-1), a broadband light source (4-2), a single-mode optical 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); The micro-nano optical fiber lithium battery in-situ detection device based on spatial optical communication comprises an optical fiber sensing system, wherein a broadband light source (4-2) provides a stable broadband optical signal, and the signal is radiated by an optical collimator (4-4) through a single-mode optical fiber jumper (4-3), respectively passes through a beam splitter (4-5), a cylindrical lens (4-6) and a light transmission port (3), and is received and coupled by a 45° inclined optical fiber grating (2-2) in an MF-TFG optical fiber probe (2). The sensing optical signal is transmitted through the micro-nano optical fiber (2 -1) area is converted into a sensing light signal by the sensing action and reflected by the metal reflective film (2-4), and then radiated by the 45° inclined fiber grating (2-2) through the optical communication window (3), and is successively collimated by the cylindrical lens (4-6), refracted by the beam splitter (4-5), reshaped and focused by the first convex lens (4-7) and the second convex lens (4-8) in free space, and then received by the CCD detector (4-9), and finally the spectral signal is processed by the signal terminal (5) to realize the in-situ detection inside the lithium battery (1).

2. According to claim 1, a micro-nano optical fiber lithium battery in-situ detection device based on spatial optical communication is characterized in that: The MF-TFG optical fiber probe (2) is made of a standard single-mode optical fiber. First, a 45° tilted optical fiber grating (2-2) is processed and engraved on one end of the optical fiber by a femtosecond laser, and the grating pitch is adjusted so that the fundamental mode interference loss peak in the transmission spectrum is located at a wavelength of 1550nm. Secondly, the coating layer at the other end of the optical fiber is removed and a micro-nano optical fiber (2-1) with a diameter of 8μm is prepared by a fusion taper method. Finally, a layer of silver metal reflective film (2-4) is plated on the end face of the micro-nano optical fiber (2-1) by a magnetron sputtering device to change the propagation direction of the optical signal to form a reflective probe. The micro-nano optical fiber (2-1) light leakage occurs due to its small diameter, thereby exciting a large proportion of evanescent field on the surface of the optical fiber, causing the transmission mode in the optical fiber to be regulated by the background refractive index. The surface of the micro-nano region of the micro-nano optical fiber (2-1) is covered with a layer of lithium ion sensitive material nanofilm (2-3). The refractive index of the material changes due to the difference in the concentration of adsorbed lithium ions, 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 membrane of crown ether functionalized graphene oxide composite chitosan combined with polychloroethanol (GO-CE-CS-PVA). According to claim 1, a micro-nano optical fiber lithium battery in-situ detection device based on spatial optical communication is characterized in that: the MF-TFG optical fiber probe (2) is implanted in the lithium battery (1) in an inverted "U" shape, wherein the micro-nano optical fiber (2-1) is fixed at the interface between the metal anode and the electrolyte of the lithium battery (1) as a sensing part, and the 45° inclined optical fiber grating (2-2) is fixed in the side packaging protection layer of the lithium battery (1) as a signal transmission end, and a glass optical communication window (3) is processed outside the packaging layer of the lithium battery (1) at the grating area, so that the lithium battery as a whole retains the original sealing environment.

3. The micro-nano optical fiber lithium battery in-situ detection device based on spatial 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 reflection spectrum of the micro-nano optical fiber (2-1).

4. A method for in-situ detection of micro-nano optical fiber lithium batteries based on spatial optical communication, the method being used for an in-situ detection device for micro-nano optical fiber lithium batteries based on spatial optical communication according to claim 1, characterized in that: The in-situ detection of the interior of the lithium battery (1) is achieved by using the wavelength drift change of the cladding mode interference presented in the spectrum received by the CCD detector (4-9) as the basis for determining the temperature, pressure and lithium ion concentration sensing inside the lithium battery (1). The spectrum information is parameter-demodulated and presented through the signal terminal (5).

5. The method for in-situ detection of micro-nano optical fiber lithium batteries based on spatial optical communication according to claim 5 is characterized in that: The temperature, pressure and lithium ion concentration are sensed inside the lithium battery (1). Specifically, each parameter acts on the micro-nano optical fiber (2-1) and the 45° tilted optical fiber grating (2-2). Due to the difference in position and function, the change of the transmission mode in the optical fiber is induced to cause the spectral drift for sensing, and special attention is paid to the migration of wavelengths corresponding to the cladding mode of the micro-nano optical fiber (2-1), the core mode of the 45° tilted optical fiber grating (2-2) and the cladding cut-off mode; wherein the lithium ion concentration affects the cladding mode; the influence of pressure deformation on the micro-nano optical fiber (2-1) located in the center of the lithium battery (1) can be ignored, but it will squeeze and deform the 45° tilted optical fiber grating (2-2) in the packaging shell of the lithium battery (1), affecting the core mode and the cladding cut-off mode; temperature affects the cladding mode, the core mode and the cladding cut-off mode at the same time.

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

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