Detection system and test method for electrochemical reaction of battery

Abstract

The invention discloses a battery electrochemical reaction detection system and a test method. The system comprises an optical detection unit, a magnetic resonance excitation unit and a data processing unit, the optical detection unit comprises an NV color center detector, and the NV color center detector is connected with the magnetic resonance excitation unit and placed in a battery electrochemical reaction solution sample to be detected; the magnetic resonance excitation unit is used for outputting a magnetic resonance regulation and control signal, influencing the quantum spin state of the NV color center and changing the intensity of an NV fluorescence signal, the collection light path collects the intensity of the fluorescence signal to the data processing unit, and an NV color center ground state spin resonance spectrum is obtained; and the data processing unit acquires the NV color center ground state spin resonance spectrum, and acquires the detection of magnetic signals, electric signals and thermal signals in the electrochemical reaction process of the battery by combining the difference response of the external magnetic field and the electric field to the NV color center ground state spin resonance frequency shift. And nanoscale and multi-parameter synchronous in-situ dynamic detection in a real battery environment is realized.

Description

Technical Field

[0001] This application relates to the technical field of battery performance testing, and more specifically, to a detection system and testing method for battery electrochemical reactions. Background Technology

[0002] With the widespread application of electrochemical energy storage devices (such as lithium-ion batteries, sodium-ion batteries, and supercapacitors), research on the electrochemical reaction mechanisms and material changes at the electrode interfaces of these devices has become a current research focus. Existing battery electrochemical detection mainly relies on some characterization techniques: spectroscopic techniques (such as in-situ X-ray diffraction and Raman spectroscopy) can analyze the evolution of the crystal structure of electrode materials, but these techniques have low spatial resolution (micrometer level) and insufficient temporal resolution (second level), making it difficult to capture nanoscale transient reactions (such as lithium dendrite nucleation); electron microscopy techniques (such as in-situ transmission electron microscopy) have atomic-level resolution, but these techniques require a high vacuum environment and are not compatible with liquid electrolytes, resulting in significant differences from actual battery operating conditions; scanning probe techniques (such as scanning electrochemical microscopy) can characterize local electrochemical activity; however, the sensitivity of this technique is limited by the probe size and is easily affected by the surface morphology of the battery.

[0003] There is currently no effective solution to the problem of achieving nanoscale and multi-parameter synchronous in-situ dynamic detection in real battery environments in related technologies. Summary of the Invention

[0004] The purpose of this application is to provide a detection system and testing method for battery electrochemical reactions, so as to solve the problem in related technologies that it is difficult to achieve in-situ dynamic detection of nanoscale and multiple parameters simultaneously in a real battery environment.

[0005] To achieve the above objectives, one embodiment of this application provides a detection system for battery electrochemical reactions. This system includes an optical detection unit, a magnetic resonance excitation unit, and a data processing unit. The optical detection unit includes an NV center detector, an excitation optical path, and a collection optical path. The NV center detector is located at the end of the optical fiber in the excitation optical path, and the NV center is located at the foremost position of the NV center detector. The radiation angle of the end of the optical fiber matches that of the NV center. The NV center detector is connected to the magnetic resonance excitation unit and is placed on the battery electrochemical reaction solution sample to be tested. The magnetic resonance excitation unit outputs a magnetic resonance modulation signal, which affects the quantum spin state of the NV center, thereby changing the intensity of the NV fluorescence signal. The collection optical path collects the intensity of the fluorescence signal and sends it to the data processing unit to obtain the ground-state spin resonance spectrum of the NV center. The data processing unit obtains the ground-state spin resonance spectrum of the NV center and, simultaneously, combines the differential response of the external magnetic field and electric field to the ground-state spin resonance frequency shift of the NV center to detect magnetic, electrical, and thermal signals during the battery electrochemical reaction process.

[0006] In some embodiments, the NV color center detector includes: a diamond probe, one end of which is a parabolic convex lens, the other end of which is bonded to the end face of the optical fiber in the excitation optical path, and the other end of which is a nanopillar containing NV color centers; the magnetic resonance excitation unit includes a copper wire, which is close to the foremost position of the NV color center detector.

[0007] In some embodiments, the detection system for the battery electrochemical reaction further includes an electrochemical testing unit. The electrochemical testing unit is used to apply current to the electrode system to drive the battery's electrochemical reaction. The electrochemical testing unit includes an electrochemical workstation, a working electrode, a counter electrode, a reference electrode, and a battery under test. The electrochemical workstation is used to apply and control electrical signals and acquire electrochemical response signals, outputting constant potential, constant current, or scanning potential, while simultaneously recording electrochemical data such as current, potential, and impedance. The working electrode is the electrode where the electrochemical reaction occurs. The counter electrode is used to close the current loop, allowing current to flow throughout the circuit. The reference electrode is used to provide a stable and known reference potential. The battery under test is an experimental platform simulating the internal environment of a battery, and contains a sample of the battery's electrochemical reaction solution.

[0008] In some embodiments, a quartz tuning fork is also attached to the sidewall of the NV color center detector, and the quartz tuning fork is used to control the displacement of the NV color center detector.

[0009] In some embodiments, the quartz tuning fork is used to control the displacement of the NV color center detector, including: controlling the NV color center detector to move downwards via a coarse adjustment displacement stage; stopping the movement of the NV color center detector when the distance between the NV color center detector and the electrode region of the battery under test is on the micrometer level; controlling the quartz tuning fork to vibrate at a preset frequency, while extracting the amplitude signal of the quartz tuning fork via a lock-in amplifier; determining the real-time position of the quartz tuning fork based on the amplitude signal; and adjusting the position of the NV color center detector in the electrode region of the battery under test via a fine adjustment displacement stage.

[0010] In some embodiments, the data processing unit acquires the ground-state spin resonance spectrum of the NV center and, in conjunction with the difference in response to the external magnetic field and electric field to the spin resonance frequency shift of the NV center, acquires the detection of magnetic, electrical, and thermal signals during the battery electrochemical reaction process. This includes: the data processing unit acquires the ground-state spin resonance spectrum of the NV center, and obtains a first resonance frequency and a second resonance frequency based on the ground-state spin resonance spectrum of the NV center, wherein the first resonance frequency is the NV center at ms=0. The resonance frequency of the transition between the two energy levels ms=+1, where the second resonance frequency is the NV color center at ms=0. The resonance frequency of the transition between two energy levels ms=-1; the magnetic signal during the battery electrochemical reaction process is obtained based on the first resonance frequency and the second resonance frequency; a standard table corresponding to the ground state spin resonance spectrum of the NV color center and temperature is determined based on a reference environment without an electric field; the offset of the ground state spin resonance spectrum of the NV color center is determined by the first resonance frequency and the second resonance frequency; the offset is compared with the data in the standard table to obtain the thermal signal during the battery electrochemical reaction process; the electrical signal during the battery electrochemical reaction process is obtained based on the magnetic signal and the thermal signal.

[0011] In some embodiments, both the excitation optical path and the collection optical path pass through a dichroic mirror spectral separation system, which is used to separate the laser and the NV fluorescence signal within the preset wavelength range.

[0012] In some embodiments, the process of matching the radiation angle of the fiber end with that of the NV color center includes the following steps: calculating the maximum acceptance angle of the fiber end based on a preset numerical aperture of the fiber end of the excitation optical path and the refractive index of the fiber in the excitation optical path; and using the waveguide effect to compress the radiation angle of the NV color center so that the radiation angle of the NV color center is lower than the maximum collection angle of the fiber end, thereby achieving the effect of matching the radiation angle of the fiber end of the excitation optical path with that of the NV color center, so as to improve the coupling efficiency of the fluorescence signal.

[0013] One aspect of this application also provides a method for testing the electrochemical reaction of a battery. The method includes: placing an NV center detector at the detection point of the working electrode of an electrochemical reaction solution; connecting a magnetic resonance excitation unit to the NV center detector; activating an electrochemical testing unit to control the movement of the NV center detector in the working electrode region of the electrochemical reaction solution, inputting laser light into the NV center detector to generate NV fluorescence signals from the NV centers on the detector; activating the magnetic resonance excitation unit to perform frequency sweeping on the NV center detector, causing a change in the spin quantum state of the NV centers on the detector; acquiring the NV fluorescence signals in real time and establishing a ground-state spin resonance spectrum of the NV centers; performing an electrochemical reaction on the electrochemical reaction solution; and combining the differential responses of the external magnetic field and electric field in the electrochemical reaction solution to the spin resonance frequency shift of the NV centers to obtain the detection of magnetic, electrical, and thermal signals during the battery electrochemical reaction process.

[0014] In some embodiments, controlling the movement of the NV color center detector in the working electrode region of the electrochemical reaction solution includes: setting a preset amplitude value; when the value of the amplitude signal does not reach the preset amplitude value, continuing to control the NV color center detector to move closer to the electrode region of the battery under test; when the value of the amplitude signal exceeds the preset amplitude value, recalibrating the position of the NV color center detector by controlling it to move up or down until the value of the amplitude signal is not greater than the preset amplitude value.

[0015] The beneficial effects of this application are: This invention provides a detection system for battery electrochemical reactions. The system includes an optical detection unit, a magnetic resonance excitation unit, and a data processing unit. The optical detection unit includes an NV center detector, an excitation optical path, and a collection optical path. The NV center detector is located at the end of the optical fiber in the excitation optical path, and the NV center is located at the foremost position of the NV center detector. The radiation angle of the end of the optical fiber is matched with that of the NV center. The NV center detector is connected to the magnetic resonance excitation unit and is used to hold the battery electrochemical reaction solution sample to be tested. The magnetic resonance excitation unit is used to output a magnetic resonance modulation signal. The magnetic resonance modulation signal affects the quantum spin state of the NV center, thereby changing the intensity of the NV fluorescence signal. The collection optical path collects the intensity of the fluorescence signal and sends it to the data processing unit to obtain the ground-state spin resonance spectrum of the NV center. The data processing unit obtains the ground-state spin resonance spectrum of the NV center and, in conjunction with the difference in response of the external magnetic field and electric field to the frequency shift of the NV center's ground-state spin resonance, obtains the detection of magnetic, electrical, and thermal signals during the battery electrochemical reaction process.

[0016] This application solves the problem of achieving nanoscale and multi-parameter synchronous in-situ dynamic detection in real battery environments, a challenge in related technologies. It enables the detection of magnetic, electrical, and thermal signals during the electrochemical reaction process in a real battery environment. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In addition, in the following drawings, the components are not necessarily drawn to scale, and components with similar related characteristics or features may have the same or similar reference numerals.

[0018] Figure 1 This is a schematic diagram of the structure of a battery electrochemical reaction detection system according to an embodiment of this application; Figure 2 This is a cross-sectional schematic diagram of a diamond probe according to an embodiment of this application; Figure 3 This is a schematic diagram of a parabolic convex lens at one end of a diamond probe according to an embodiment of this application; Figure 4 This is a schematic diagram of a nanopillar at one end of a diamond probe according to an embodiment of this application; Figure 5 This is a side view schematic diagram of the NV color center detector according to an embodiment of this application; Figure 6 This is a flowchart of a test method for a battery electrochemical reaction detection system according to an embodiment of this application; Figure 7 This is a schematic diagram of a battery electrochemical reaction detection system according to an embodiment of the application; Figure 8 This is a schematic diagram of a detection system for the electrochemical reaction of a self-assembled battery according to an embodiment of this application. Detailed Implementation

[0019] To make the technical problems, technical solutions and beneficial effects to be solved by this application clearer, the following describes this application in further detail with reference to the accompanying drawings and embodiments.

[0020] In the description of this application, it should be noted that the use of terms such as "first" and "second" to define objects (such as elements, components, regions, layers, doping types and / or parts) is merely for the purpose of distinguishing different objects and is not necessarily used to describe a specific order or sequence. Unless the context clearly indicates otherwise, it should be understood that such data can be used interchangeably where appropriate.

[0021] In the description of this application, it should be understood that the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “compose” and / or “comprise” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0022] In the description of this application, it should also be noted that when a component is referred to as "on another component," "connected to another component," or "in contact with another component," it can mean not only that a component is directly on, directly connected to, or directly in contact with another component, but also that an intermediate component can be inserted between the two components. Furthermore, "connection" includes not only fixed connections but also detachable connections or integral connections. Similarly, when an element is referred to as "electrically connected," "electrically contacted," "electrically coupled," or "electrically coupled to" another element, the two elements can be in direct electrical contact or point coupling, or they can be in electrical contact or point coupling through an intermediate component.

[0023] In the description of this application, it should also be noted that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0024] Furthermore, in the description of this application, spatial relation terms such as "below," "under," "below," "below," "below," "above," "on the upper surface of," "above," etc., can be used to describe the spatial positional relationship between one element or feature shown in the figures and other elements or features. It should be understood that spatial relation terms, in addition to the orientation shown in the figures, also include different orientations of elements or features in use and operation. For example, if an element or feature in the figures is flipped or inverted, an element or feature described as "below" or "below" other elements or features will be oriented "above" other elements or features. Furthermore, elements may also include other orientations (e.g., rotated by an angle or other orientations).

[0025] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application: An NV center is a light-emitting defect in a diamond lattice formed by a nitrogen atom replacing a carbon atom and creating a neighboring carbon vacancy. It is a unique three-level quantum system. Optical fibers transmit light of different wavelengths to the NV center in diamond, enabling energy level transitions and quantum state initialization. When an electron in the NV center's quantum system returns from a high energy level to a low energy level, the NV center emits fluorescence, which is then conducted out through the optical fiber. The magnetometry principle of the NV center is as follows: the fluorescence intensity emitted by the NV center varies depending on the spin quantum state of the electron. When a microwave field is applied to the NV center through a copper coil structure at a certain frequency, it induces electron spin resonance in the NV center's quantum system, changing the electron's spin quantum state and consequently altering the fluorescence intensity emitted by the NV center. Because the resonance frequency of the electron's spin quantum state is affected by different external magnetic field strengths, the ground state spin resonance spectrum of the NV color center can be obtained through the above-mentioned magnetic measurement principle of the NV color center, the NV color center detector for detecting the electrochemical reaction of the battery, and the high-precision nanoscale displacement stage, thus realizing the imaging of multiple physical quantities such as temperature and electric field at the nanoscale spatial resolution.

[0026] According to an embodiment of this application, a detection system for battery electrochemical reactions is provided.

[0027] Figure 1 This is a structural diagram of a battery electrochemical reaction detection system according to an embodiment of this application. Figure 1 As shown, the detection system includes: an electrochemical testing unit 101, an optical detection unit 102, a magnetic resonance excitation unit 103, and a data processing unit 104.

[0028] The electrochemical testing unit 101 is used to apply current to the electrode system to drive the electrochemical reaction of the battery. The electrochemical testing unit includes an electrochemical workstation, a working electrode, a counter electrode, a reference electrode, and the battery under test. The electrochemical workstation is used to apply and control electrical signals and acquire electrochemical response signals. It can output constant potential, constant current, or scanning potential, while simultaneously recording electrochemical data such as current, potential, and impedance. The working electrode is the electrode where the electrochemical reaction occurs. The working electrode and the NV color center detector of the optical detection unit are integrated into one unit, meaning they share a single potential. The counter electrode is used to close the current loop, allowing current to flow throughout the circuit. The reference electrode is used to provide a stable and known reference potential. The battery under test is an experimental platform simulating the internal environment of a battery.

[0029] The optical detection unit 102 is used to emit and transmit laser light and collect fluorescence after laser excitation. The optical detection unit includes an NV center detector, an excitation optical path, and a collection optical path. The NV center detector is located at the end of the optical fiber of the excitation optical path, and the NV center is located at the foremost position of the NV center detector. The radiation angle of the end of the optical fiber is matched with that of the NV center. The NV center detector is connected to the magnetic resonance excitation unit and is used to place the electrochemical reaction solution sample of the battery to be tested.

[0030] The excitation optical path consists of a tunable laser, a polarizer, a lens array, a dichroic mirror, and a fiber coupler connected in sequence. The collection optical path contains only a dichroic mirror and a fiber coupler, using the same dichroic mirror and fiber coupler as the excitation optical path. A tunable laser is a laser whose emission wavelength can be continuously changed within a certain range, providing laser light of different wavelengths. A polarizer is a filter that allows light to pass through only in a specific direction of vibration, controlling the polarization state of the laser light to ensure that the light entering the test cell is linearly, circularly, or polarized in a specific direction, thereby improving excitation efficiency or reducing reflection noise. A lens array is a group of small lenses arranged geometrically, used for beam shaping or homogenization. A dichroic mirror is an optical element that selectively reflects or transmits light according to wavelength, separating laser and fluorescence.

[0031] In this embodiment, both the excitation and collection optical paths pass through a dichroic mirror. The dichroic mirror is used to separate the laser and NV fluorescence signals within a preset wavelength range. It reflects the green laser to the NV color center detector and transmits the red fluorescence from the NV color center detector. An optical fiber coupler is an interface structure used to split, combine, or extend optical fiber links for laser signals.

[0032] A side view of the NV color center detector is shown below. Figure 5 As shown, it specifically includes: a diamond probe (such as...) Figure 2 As shown), one end of the diamond probe is a parabolic convex lens (such as...). Figure 3As shown), one end of the diamond probe with a convex lens is bonded to the end face of the optical fiber in the excitation optical path, and the other end of the diamond probe is a nanopillar containing NV color centers (such as...). Figure 4 (As shown); the magnetic resonance excitation unit includes copper wires, which are positioned close to the front end of the NV color center detector.

[0033] The NV color center detector also has a quartz tuning fork attached to its sidewall. The quartz tuning fork is used to control the displacement of the NV color center detector. The copper wire is located at the end of the optical fiber in the excitation optical path and is close to the diamond probe.

[0034] Specifically, the radius of curvature of a parabolic convex lens is 5μm~10μm, such as... Figure 3 As shown, the radius of the right sphere of the parabolic convex lens can be 9.588 μm, and the nanopillar containing NV color centers is as follows: Figure 4 As shown, the nanopillar has a diameter of 300 nm and a height of 2 μm, and it has a conical structure. The reason for designing one end of the diamond probe as a parabolic convex lens and the other end as a nanopillar structure containing NV color centers is that this composite structure enhances the excitation efficiency and fluorescence collection efficiency of the NV color centers. The laser emitted through the optical fiber is a Gaussian beam, which inherently has some divergence. Since there is a distance between the fiber end face and the NV color center of the diamond probe, only a small amount of green light (which is included in the laser) can enter the nanopillar of the NV color center, resulting in a low NV color center excitation efficiency. By reverse-engineering a parabolic lens at the fiber core corresponding to the nanopillar of the NV color center, the laser light can be shaped and focused before entering the nanopillar, increasing the laser power density and thus improving the NV color center excitation efficiency. The fluorescence collection process involves collecting the NV fluorescence signal generated by the NV color center after laser excitation. The nanopillar structure of the NV color center allows the NV fluorescence signal to be shaped and focused before entering the end of the optical fiber, reducing the light exit angle at the surface boundary of the diamond probe, lowering the total internal reflection characteristics of the diamond probe, and improving the fluorescence collection efficiency.

[0035] The design steps for the diamond probe, which has a parabolic convex lens at one end and a nanopillar at the other, are as follows: First, simulation is performed, and then a diamond probe that meets the experimental requirements is fabricated based on the simulation results. During the simulation, a fiber-diamond composite waveguide model is established. This model includes simulating the focusing behavior of a 532nm wavelength Gaussian beam on the convex lens of the diamond probe, optimizing the spot size to below 500nm and the beam power density to above 1MW / cm². 2The nanopillar structure utilizes the optical waveguide effect to modulate the fluorescence radiation direction of the NV color centers within the nanopillar, increasing the NV color center excitation efficiency to 45% and the fluorescence collection efficiency from 5.3% to over 65%, a 3.8-fold improvement over traditional structures. Based on simulation results, a diamond probe meeting experimental requirements was fabricated. The fabrication process employed electron beam lithography and focused ion beam etching to prepare the required diamond probe on a diamond substrate. The diamond probe structure consisted of a parabolic convex lens at one end and a nanopillar at the other. A self-aligned process was used to achieve deterministic implantation of a single NV color center, resulting in a nanopillar containing the NV color center.

[0036] Furthermore, the structural design of the nanopillar section utilizes the optical waveguide effect to modulate the fluorescence radiation direction of the NV center. The principle of the optical waveguide effect is that after the NV center is excited by laser in diamond, its fluorescence emission is essentially isotropic, meaning photons propagate uniformly in all directions. This results in most of the fluorescence not being effectively collected into the fiber core, thus requiring manipulation of the NV center's fluorescence radiation direction. After establishing a fluorescence collection efficiency model, to match the radiation angle of the fiber end of the excitation optical path with that of the NV center, the matching process includes the following steps: calculating the maximum acceptance angle of the fiber end based on the preset numerical aperture and refractive index of the fiber; and using the optical waveguide effect to compress the radiation angle of the NV center, making it lower than the maximum collection angle of the fiber end, thereby achieving the effect of matching the radiation angle of the fiber end of the excitation optical path with that of the NV center, thus improving the coupling efficiency of the fluorescence signal.

[0037] The maximum acceptance angle at the end of the optical fiber is calculated using the numerical aperture formula for optical fiber, as shown in formula (1) below: NA=n sinθ max (1) Where NA is the numerical aperture of the optical fiber, n is the refractive index, and θ is the refractive index. max The maximum acceptance angle is θ. In this embodiment, NA is approximately 0.4, and the refractive index of the fiber core is 1.45. Therefore, the maximum acceptance angle θ at the end of the fiber can be calculated. max ≈15.98°.

[0038] The radiation angle of the NV color center is compressed using the optical waveguide effect. The specific steps are as follows: a diamond side-section is used in conjunction with an asymmetric tapered fiber structure (such as...). Figure 5The optical design (shown in the fiber portion of the NV center detector's structural diagram) can compress the radiation angle of the NV center from isotropic to ±15°. Under natural conditions, the radiation angle of the NV center is isotropic, meaning that light inside the diamond propagates in all directions. When the radiation angle of the NV center is lower than the maximum collection angle at the fiber end, it means that the fluorescence emitted by the NV center can be well coupled into the fiber core, thus achieving radiation angle matching. Furthermore, the fiber in the excitation path uses high-purity lime fiber with low fluorescence background, a cladding diameter of 125 μm, and a core diameter of approximately 5 μm. The fiber end is designed with an asymmetric tapered structure. Through micron-level tapering technology, the fiber end is geometrically reconstructed, compressing the output beam waist of the excitation path fiber end to the micron level, and increasing the power density of the Gaussian beam input to the excitation path by 2-3 orders of magnitude. After the fiber end is aligned with the nanopillar of the NV color center, it is connected together with a UV adhesive with a refractive index similar to that of the fiber and diamond. The nanopillar of the NV color center has a diameter of about 300nm, and the UV adhesive is a UV-curing adhesive.

[0039] The magnetic resonance excitation unit 103 outputs a magnetic resonance modulation signal. This signal influences the quantum spin state of the NV color center, thereby altering the intensity of the NV fluorescence signal. The intensity of the fluorescence signal is collected by the optical collection path and sent to the data processing unit to obtain the ground-state spin resonance spectrum of the NV color center. The magnetic resonance excitation unit includes a microwave source, a power amplifier, a transmission line, and a copper wire. The microwave source generates continuous waves or pulsed microwaves to drive the spin transitions of the NV color center. The power amplifier amplifies the microwaves to sufficient power to ensure that the magnetic field near the copper wire can effectively drive the spin. The copper wire is located at the end of the optical fiber in the excitation optical path, close to the diamond probe. The transmission line transmits the microwaves from the source to the copper wire, which outputs the magnetic resonance modulation signal. This signal influences the quantum spin state of the NV color center, thereby altering the intensity of the NV fluorescence signal.

[0040] Specifically, in this embodiment, a microwave source is used to drive the electron spin transition of the NV center in the diamond probe. The ground-state electron spin of the NV center has an energy level structure of ms=0 and ms=±1. After the static magnetic field is applied, the energy levels of ms=+1 and ms=-1 split, resulting in an energy difference. When the frequency of the applied microwave matches this energy difference, the NV center undergoes electron spin resonance, causing its spin state to change from ms=0 to ms=±1. Different electron spin quantum states correspond to different fluorescence intensities. Different external magnetic field strengths lead to different energy differences in the energy level splitting, causing a shift in the resonance frequency corresponding to the energy difference. Therefore, the magnitude of the magnetic field can be deduced from the relationship between fluorescence intensity and microwave frequency, thus enabling the detection of the magnetic field.

[0041] The data processing unit 104 is used to acquire the ground state spin resonance spectrum of the NV color center, and at the same time, combined with the difference response of the external magnetic field and electric field to the ground state spin resonance frequency shift of the NV color center, to acquire the detection of magnetic signals, electrical signals and thermal signals in the electrochemical reaction process of the battery.

[0042] Specifically, the data processing unit acquires the ground-state spin resonance spectrum of the NV center and, combined with the difference in response to the external magnetic field and electric field to the spin resonance frequency shift of the NV center, obtains the detection of magnetic, electrical, and thermal signals during the battery electrochemical reaction process. This includes: the data processing unit acquires the ground-state spin resonance spectrum of the NV center, and based on the NV center ground-state spin resonance spectrum, obtains the first resonance frequency and the second resonance frequency, where the first resonance frequency is the frequency of the NV center at ms=0. The resonance frequency of the transition between the two energy levels ms=+1, and the second resonance frequency is the NV color center at ms=0. The resonance frequency of the transition between the two energy levels ms=-1 is determined; the magnetic signal during the battery electrochemical reaction process is obtained based on the first and second resonance frequencies; a standard table of the ground state spin resonance spectrum of the NV color center corresponding to temperature is determined based on a reference environment without an electric field; the offset of the ground state spin resonance spectrum of the NV color center is determined by the first and second resonance frequencies; the offset is compared with the data in the standard table to obtain the thermal signal during the battery electrochemical reaction process; and the electrical signal during the battery electrochemical reaction process is obtained based on the magnetic and thermal signals.

[0043] The resonance peak splitting difference, i.e., the distance between the two peaks, can be obtained from the ground-state spin resonance spectrum of the NV color center. This difference is only affected by the magnetic field, and therefore, the magnetic signal can be decoupled using the resonance peak splitting difference. In this embodiment, the first resonance frequency is the resonance frequency of the electron spin transition between ms=0 and ms=+1, denoted as […]. The second resonance frequency is the resonance frequency of the electron spin transition between ms=0 and ms=-1, denoted as , and Each has a linear expression, such as formula (2) and formula (3): Formula (2) Formula (3) Subtracting formula (2) from formula (3), we get formula (4): Formula (4) in, The difference in resonance peak splitting is denoted as . , It is the zero-field reference frequency. The electron gyromagnetic ratio is 28 MHz / mT.

[0044] Furthermore, the magnetic signal can be decoupled, as shown in formula (5): Formula (5) To decouple the thermal signal from the electrical signal, it is necessary to first obtain the ground-state spin resonance spectrum of the NV center under an electric field-free reference environment (i.e., zero-field reference) and determine its corresponding standard table for temperature. Then, based on the standard table, determine the temperature corresponding to the offset of the ground-state spin resonance spectrum of the NV center under actual operating conditions. The temperature corresponding to the above is the thermal signal. The average frequency shift of the resonance peak can also be obtained through the ground-state spin resonance spectrum of the NV center. The average frequency shift of the resonance peak represents the offset of the peak center of the resonance spectrum relative to the zero-field reference frequency. It is affected by the electric field, temperature and energy level splitting changes. The response laws of the three to the frequency shift are independent of each other and satisfy the principle of linear superposition. The formula (6) for the average frequency shift of the resonance peak is as follows: Formula (6) The relationship between the average frequency shift of the resonance peak, the electric field, and the temperature can be expressed by formula (7): Formula (7) in, , The average frequency shift component caused by the electric field. , This is the average frequency shift component caused by temperature. The Stark coefficient in the z-axis direction is approximately 1.4 × 10⁻⁶. -9 GHz m / V, This is the temperature coefficient, with a value of approximately 7.6 × 10⁻⁶. -4 GHz / K.

[0045] In a reference environment without an electric field Since the value is 0, the change in temperature can be obtained as formula (8): Formula (8) The standard gauge can be determined by changing the temperature, and the thermal signal can be obtained from the standard gauge in actual working conditions.

[0046] In actual working conditions, substituting the actual real-time temperature value into formula (7) yields the electrical signal, as shown in formula (9): Formula (9) During the charging and discharging process of the battery under test, the ground state spin resonance spectrum of the NV color center is obtained by microwave frequency scanning. Then, combined with the difference response of the external magnetic field and electric field to the resonance frequency shift (Δf=28GHz / T, Δλ=0.1nm / (V / μm)), the magnetic signal, electrical signal and thermal signal are decoupled with a decoupling error of <5%. The microwave frequency is 2.87GHz~2.95GHz, and the linewidth of the ground state spin resonance spectrum of the NV color center is <3MHz.

[0047] Figure 6 This is a flowchart of a test method for a battery electrochemical reaction detection system according to an embodiment of this application, such as... Figure 6 As shown, the method includes: Step S701: Place the NV color center detector at the detection point of the working electrode of the electrochemical reaction solution.

[0048] Step S702: Connect the magnetic resonance excitation unit to the NV color center detector.

[0049] Step S703: Start the electrochemical testing unit, control the movement of the NV color center detector in the working electrode area of ​​the electrochemical reaction solution, and input laser light into the NV color center detector so that the NV color centers on the NV color center detector generate NV fluorescence signals.

[0050] Step S704: The magnetic resonance excitation unit is activated to perform frequency sweeping on the NV color center detector, thereby changing the spin quantum state of the NV color center on the NV color center detector, and the NV fluorescence signal is acquired in real time to establish the ground state spin resonance spectrum of the NV color center.

[0051] Step S705: Perform an electrochemical reaction on the electrochemical reaction solution.

[0052] Step S706: By combining the differential response of the external magnetic field and electric field in the electrochemical reaction solution to the spin resonance frequency shift of the NV color center ground state, the magnetic signal, electrical signal and thermal signal during the battery electrochemical reaction process are obtained.

[0053] Specifically, controlling the movement of the NV color center detector in the working electrode region of the electrochemical reaction solution includes: Before the working electrode of the electrochemical reaction solution begins operation, the sidewall of the quartz tuning fork is bonded to the sidewall of the NV color center detector. The displacement of the NV color center detector is controlled by controlling the quartz tuning fork. Then, the NV color center detector is moved downwards by a coarse adjustment displacement stage to approach the electrode area of ​​the battery under test. When the distance reaches the micrometer level, the movement of the NV color center detector is stopped, and the distance control feedback system is activated. A fixed drive is input to the quartz tuning fork to maintain a certain frequency of vibration. The oscillation source of the quartz tuning fork is designed as a dual-frequency resonant drive module (32kHz fundamental frequency + 128kHz harmonic frequency), and the amplitude signal of the quartz tuning fork is acquired by a lock-in amplifier. After the battery under test begins operation, the real-time position of the quartz tuning fork is determined based on the amplitude signal. The position of the NV color center detector in the working electrode area of ​​the electrochemical reaction solution is adjusted by a fine adjustment displacement stage, controlling the NV color center detector to perform nanometer-level step displacement.

[0054] A fully fiber-optic dual-channel signal acquisition system (signal-to-noise ratio > 20dB) was constructed using a PID algorithm and lock-in amplification technology, achieving nanometer-level stable control of the probe-electrode spacing (drift < 100nm / h) in an electrolyte environment. A preset amplitude value was set. When the amplitude signal value did not reach the preset value, the NV color center detector continued to move closer to the working electrode region of the electrochemical reaction solution. When the amplitude signal value exceeded the preset value, the NV color center detector was repositioned by moving up or down until the amplitude signal value was no greater than the preset value.

[0055] The principle of controlling the NV color center detector is as follows: for macroscopic positioning, an electromagnetic coil is used to achieve coarse positioning of the probe at the millimeter level with an accuracy of ±500μm; for mesoscopic positioning, a micrometer-level precise positioning is achieved based on the NV color center magnetometer with an accuracy of ±1μm; for nanometer-level positioning, the final 100nm approximation is achieved by shifting the resonant frequency of a quartz tuning fork.

[0056] When the quartz tuning fork is brought close to the electrode, its original amplitude will change. The coarse adjustment stage is used to adjust the position of the quartz tuning fork in the z-axis direction when the quartz tuning fork is far from the working electrode area of ​​the electrochemical reaction solution. The fine adjustment stage is used to adjust the distance between the quartz tuning fork and the working electrode area of ​​the electrochemical reaction solution when the distance between the quartz tuning fork and the electrode area of ​​the battery under test is at the micrometer level.

[0057] The testing method of the battery electrochemical reaction detection system provided in this application embodiment involves placing an NV center detector at the detection point of the working electrode in the electrochemical reaction solution; connecting a magnetic resonance excitation unit to the NV center detector; activating the electrochemical testing unit to control the movement of the NV center detector in the working electrode region of the electrochemical reaction solution, inputting laser light to the NV center detector to generate NV fluorescence signals; activating the magnetic resonance excitation unit to sweep the frequency of the NV center detector, causing a change in the spin quantum state of the NV center on the NV center detector, acquiring the NV fluorescence signal in real time and establishing the ground state spin resonance spectrum of the NV center; performing an electrochemical reaction in the electrochemical reaction solution; and combining the difference in response of the external magnetic field and electric field in the electrochemical reaction solution to the frequency shift of the ground state spin resonance of the NV center to obtain the detection of magnetic, electrical, and thermal signals during the battery electrochemical reaction process. This solves the problem in related technologies of the difficulty in achieving nanoscale and multi-parameter synchronous in-situ dynamic detection in a real battery environment. Thus, it achieves the effect of battery electrode electrochemical reaction measurement and in-situ electrode monitoring of the solution environment based on fiber-optic integrated diamond sensors.

[0058] Figure 7 This is a schematic diagram of a battery electrochemical reaction detection system according to an embodiment of the application. The detection system can be divided into four parts: laser input, battery electrochemical reaction device, fluorescence output, and data analysis. Figure 7 ① is the laser input section, which includes: a tunable laser source, a polarizer, and a lens array. Figure 7 Section ② is the fluorescence output section, which is used to output fluorescence signals to the optical signal analyzer. Figure 7 ① and Figure 7 ② They share the same dichroic mirror to process laser or fluorescence signals, and the dichroic mirror is connected to a fiber coupler. Figure 7 ③ is an optical fiber, which serves as a shared component for both laser input and fluorescence output. A high-purity silica fiber with low fluorescence background is used to construct a dual-channel optical transmission system. The optical fiber is used to transmit two wavelengths of light: one is a green laser (wavelength 532nm) that excites the NV color center, and the other is red fluorescence (650nm~800nm) generated after the NV color center is excited by the laser. The laser is input into the battery electrochemical reaction device, and the fluorescence signal is output from the battery electrochemical reaction device. Figure 7The electrochemical workstation in the device is a battery electrochemical reaction device, which includes a working electrode (WE), a counter electrode (CE), and a reference electrode (RE). The NV color center detector shares a point with the working electrode, and an external microwave is used to apply a microwave field to the NV color center. Figure 7 The fiber position controller, also known as the quartz tuning fork mentioned above, is used to control the position movement of the NV color center detector. The sidewalls of the quartz tuning fork are bonded to the sidewalls of the fiber optic end. The working electrode, counter electrode, and reference electrode are all connected to an electrochemical workstation, which is in turn connected to a computer, which is then connected to an optical signal analyzer.

[0059] Figure 8 This is a schematic diagram of a detection system for the electrochemical reaction of a self-assembled battery according to an embodiment of this application, as shown below. Figure 8As shown, a 532nm laser is input into the system. Its polarization direction is adjusted by a half-wave plate and a polarizing beam splitter. Then, a lens focuses the laser onto the optical crystal of an acousto-optic modulator. After passing through the modulator, the laser undergoes Bragg diffraction, producing multiple diffraction spots. An aperture is used to select a first-order diffraction spot, and a 200mm focal length converging lens is used to level the laser. The adjusted laser then passes through a quarter-wave plate and is reflected by a mirror to the polarizing beam splitter (the same optical device as the polarizing beam splitter mentioned above). After passing through the polarizing beam splitter, the laser passes through another mirror to a dichroic mirror. After the dichroic mirror, the laser reaches the microscope objective and is then transmitted via a fiber coupler to the diamond probe of the NV color center detector. In the diamond probe, the NV color center emits a fluorescence signal after being stimulated by a laser. This fluorescence signal is transmitted to a dichroic mirror via the same optical fiber as the laser input. The dichroic mirror separates the laser and fluorescence. The red fluorescence is transmitted to an avalanche photodiode (APD) via a microscope objective and an optical filter. The APD is connected to a data acquisition module to simultaneously acquire fluorescence intensity and lifetime signals (time resolution 100 ns). A microwave source (MW source) is used to output a magnetic resonance modulation signal to influence the quantum spin state of the NV color center. A quartz tuning fork is attached to the sidewall of the fiber optic end. An oscillating source is used to drive the quartz tuning fork to maintain a stable vibration state. The quartz tuning fork is used to control the longitudinal Z-axis displacement of the NV color center detector (corresponding to...). Figure 8 The Z-axis longitudinal scan is used to achieve Z-axis displacement control via piezoelectric feedback, with an accuracy range of ±50 nm. Because the vibration of the quartz tuning fork is affected by the sample, a lock-in amplifier (corresponding to...) is used... Figure 8 The lock-in amplifier in the circuit collects amplitude signals and uses a PID algorithm to adjust the position of the NV color center detector, so that the distance between the NV color center detector and the battery under test is always kept constant.

[0060] After determining the position of the electromagnetic field to be measured along the longitudinal Z-axis, the electromagnetic field to be measured is scanned laterally using an XY displacement stage (corresponding to...). Figure 8(Through XY lateral scanning), the electromagnetic field magnitude at each position in the lateral direction can be measured using the NV color center, ultimately yielding the two-dimensional electromagnetic field distribution of the battery under test in a specific Z-axis. By changing the Z-axis value and repeating the lateral scanning operation, multiple two-dimensional electromagnetic field distributions with different Z-axis values ​​can be obtained. Combining these multiple Z-axis distributions yields the three-dimensional electromagnetic field distribution of the battery under test. The operation steps for measuring other physical fields are similar to those for measuring the three-dimensional electromagnetic field.

[0061] During the electrochemical reaction process of a battery, lithium dendrites can grow. Once they grow, they can cause serious consequences, such as puncturing the battery separator, causing an internal short circuit, reducing battery capacity, and thus shortening battery life. Considering the adverse effects of lithium dendrite growth, it is necessary to monitor the charging and discharging process of the battery under test. By analyzing the detected physical quantities of the battery, we can obtain data on the changes in the battery during charging and discharging. If there is an abnormal increase in the local magnetic field, a concentration of the electric field, or an abnormal temperature gradient, it indicates that the local current density is increasing and the internal reaction rate of the battery is running out of control. This allows for early warning of the battery's electrochemical reaction before lithium dendrites form.

[0062] The process of monitoring lithium dendrite growth can be divided into two parts: first, imaging using a magnetic field gradient. By locating lithium dendrite nucleation sites and combining this with correlation analysis between fluorescence lifetime (τ) and temperature (T1 relaxation), a quantitative equation was established for the lithium dendrite growth rate (v = 1~10 nm / s) and the local heat generation rate (Q > 1 mW / μm³). The magnetic field gradient represents the partial derivative of the magnetic field with respect to a certain direction x in space, and the magnetic field gradient represents the rate of change of the magnetic field along the x-direction. This means the magnetic field gradient is directly related to the current density distribution. Lithium dendrite growth is accompanied by local current density changes, forming a detectable magnetic field gradient. Therefore, the nucleation location of lithium dendrites can be indirectly located through magnetic field gradient imaging. Secondly, the evolution of the battery electrolyte interface (SEI) film is correlated with impedance. The Stark displacement of the electric field is used to measure the electric field strength at the solid-liquid interface of the battery. The Stark displacement range is Δλ = 0.05 nm to 0.2 nm, and the electric field strength ranges from 0.1 MV / m to 1 MV / m. Finally, the exponential relationship between the SEI film thickness growth and the charge transfer resistance (Rct) is inverted using time-domain impedance spectroscopy (EIS). The SEI film thickness growth ranges from 0.1 nm to 10 nm, and Rct ∝ exp(dSEI / λT), where λT = 0.5 nm.

[0063] The collected monitoring data is fused at multiple scales, and machine learning-assisted diagnosis is employed to construct a deep convolutional neural network (DCNN). Multi-physics data from NV color center detection, including magnetic field, electric field, and temperature, are used as input to the neural network. This yields outputs for electrode active lithium loss rate (ΔQ = 0.1%~5%), internal resistance increase (ΔR = 0.01Ω~1Ω), and thermal runaway risk coefficient (0~1). The model training utilizes a transfer learning strategy, achieving a warning accuracy of >90% across battery systems (liquid / solid).

[0064] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0065] It should be noted that, where there is no conflict, the features in the different embodiments of this application described above can be combined with each other. Furthermore, in each of the above embodiments, the focus is on describing the differences from other embodiments; other specific descriptions of the same / similar parts between the embodiments can be referred to (or referenced) interchangeably. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this application.

[0066] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A detection system for battery electrochemical reactions, characterized in that, include: Optical detection unit, magnetic resonance excitation unit, and data processing unit; The optical detection unit includes: an NV color center detector, an excitation optical path, and a collection optical path. The NV color center detector is located at the end of the optical fiber in the excitation optical path, and the NV color center is located at the foremost position of the NV color center detector. The radiation angle of the end of the optical fiber matches that of the NV color center. The NV color center detector is connected to the magnetic resonance excitation unit and is placed on the electrochemical reaction solution sample of the battery to be tested. The NV color center detector includes: A diamond probe, one end of which is a parabolic convex lens, the other end of which is bonded to the end face of the optical fiber in the excitation optical path, and the other end of which is a nanopillar containing NV color centers. The magnetic resonance excitation unit is used to output a magnetic resonance modulation signal, which affects the quantum spin state of the NV color center, thereby changing the intensity of the NV fluorescence signal. The collecting optical path collects the intensity of the fluorescence signal and sends it to the data processing unit to obtain the ground state spin resonance spectrum of the NV color center. The data processing unit obtains the ground state spin resonance spectrum of the NV color center and, in conjunction with the difference in response of the external magnetic field and electric field to the spin resonance frequency shift of the NV color center, obtains the detection of magnetic, electrical, and thermal signals during the electrochemical reaction process of the battery.

2. The detection system for battery electrochemical reactions according to claim 1, characterized in that, The magnetic resonance excitation unit includes a copper wire, which is positioned close to the foremost edge of the NV color center detector.

3. The detection system for battery electrochemical reactions according to claim 1, characterized in that, It also includes an electrochemical testing unit for applying current to the electrode system to drive the electrochemical reaction of the battery. The electrochemical testing unit includes an electrochemical workstation, a working electrode, a counter electrode, a reference electrode, and a battery under test. The electrochemical workstation is used to apply and control electrical signals and acquire electrochemical response signals, output constant potential, constant current, or scanning potential, and simultaneously record electrochemical data such as current, potential, and impedance. The working electrode is the electrode where the electrochemical reaction occurs. The counter electrode is used to close the current loop, allowing current to flow in the entire circuit. The reference electrode is used to provide a stable and known reference potential. The battery under test is an experimental platform simulating the internal environment of the battery, and the battery under test contains a sample of the electrochemical reaction solution of the battery under test.

4. The detection system for battery electrochemical reactions according to claim 1, characterized in that, The NV color center detector also has a quartz tuning fork attached to its sidewall, which is used to control the displacement of the NV color center detector.

5. The detection system for battery electrochemical reactions according to claim 4, characterized in that, The quartz tuning fork is used to control the displacement of the NV color center detector, including: The NV color center detector is controlled to move downward by coarse adjustment of the displacement stage. When the distance between the NV color center detector and the electrode area of ​​the battery under test is on the micrometer level, the movement of the NV color center detector is stopped. The quartz tuning fork is controlled to vibrate at a preset frequency, and the amplitude signal of the quartz tuning fork is extracted through a lock-in amplifier. The real-time position of the quartz tuning fork is determined based on the amplitude signal, and the position of the NV color center detector in the electrode region of the battery under test is adjusted by fine-tuning the displacement stage.

6. The detection system for battery electrochemical reactions according to claim 1, characterized in that, The data processing unit acquires the ground-state spin resonance spectrum of the NV color center, and simultaneously combines the differential responses of the external magnetic field and electric field to the ground-state spin resonance frequency shift of the NV color center to obtain the detection of magnetic, electrical, and thermal signals during the battery electrochemical reaction process, including: The data processing unit acquires the ground-state spin resonance spectrum of the NV color center, and obtains a first resonance frequency and a second resonance frequency based on the ground-state spin resonance spectrum of the NV color center, wherein the first resonance frequency is the frequency of the NV color center at ms=0. The resonance frequency of the transition between the two energy levels ms=+1, where the second resonance frequency is the NV color center at ms=0. The resonance frequency of the transition between two energy levels when ms=-1; The magnetic signal during the battery electrochemical reaction process is obtained based on the first resonance frequency and the second resonance frequency; Based on a standard table that determines the ground state spin resonance spectrum of the NV color center and its temperature under an electric field-free reference environment, the offset of the ground state spin resonance spectrum of the NV color center is determined by the first resonance frequency and the second resonance frequency. The offset is compared with the data in the standard table to obtain the thermal signal during the battery electrochemical reaction process. The electrical signals during the battery electrochemical reaction process are obtained based on the magnetic and thermal signals.

7. The detection system for battery electrochemical reactions according to claim 1, characterized in that, Both the excitation optical path and the collection optical path pass through a dichroic mirror spectral separation system, which is used to separate the laser and the NV fluorescence signal within the preset wavelength range.

8. The detection system for battery electrochemical reactions according to claim 1, characterized in that, The process of matching the radiation angle of the fiber end with that of the NV color center includes the following steps: Based on the preset numerical aperture of the fiber end of the excitation optical path and the refractive index of the fiber of the excitation optical path, the maximum acceptance angle of the fiber end is calculated. By utilizing the optical waveguide effect to compress the radiation angle of the NV color center, making the radiation angle of the NV color center lower than the maximum collection angle at the end of the optical fiber, the radiation angle of the end of the excitation optical path is matched with that of the NV color center, thereby improving the coupling efficiency of the fluorescence signal.

9. A testing method for a battery electrochemical reaction detection system based on any one of claims 1-8, characterized in that, include: The NV color center detector is placed at the detection point of the working electrode in the electrochemical reaction solution; Connect the magnetic resonance excitation unit to the NV color center detector; The electrochemical testing unit is activated, and the NV color center detector is moved in the working electrode area of ​​the electrochemical reaction solution. Laser is input into the NV color center detector, so that the NV color center on the NV color center detector generates NV fluorescence signal. The magnetic resonance excitation unit is activated to sweep the frequency of the NV color center detector, thereby changing the spin quantum state of the NV color center on the NV color center detector. The NV fluorescence signal is collected in real time and the ground state spin resonance spectrum of the NV color center is established. An electrochemical reaction is carried out on the electrochemical reaction solution; By combining the differential responses of the external magnetic field and electric field in the electrochemical reaction solution to the spin resonance frequency shift of the ground state of the NV color center, the magnetic, electrical, and thermal signals during the battery electrochemical reaction process can be detected.

10. The test method according to claim 9, characterized in that, Controlling the movement of the NV color center detector in the working electrode region of the electrochemical reaction solution includes: A preset amplitude value is set. When the amplitude signal value does not reach the preset amplitude value, the NV color center detector continues to be controlled to move closer to the electrode area of ​​the battery under test. When the value of the amplitude signal exceeds the preset amplitude value, the position of the NV color center detector is recalibrated by controlling it to move up or down until the value of the amplitude signal is no greater than the preset amplitude value.

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