Electrochemical component testing device and detection method

Abstract

The invention discloses an electrochemical component detection device and a detection method. The electrochemical component testing device comprises a Raman spectrum unit and a gas detection unit, the gas detection unit comprises an optical fiber gas sensor and a gas pipeline which are communicated with each other, and the Raman spectrum unit is configured to be capable of emitting light to irradiate the optical fiber gas sensor. The gas pipeline is used for supplying gas generated by the electrochemical component to the optical fiber gas sensor and then conveying the gas back into the electrochemical component. The device can realize real-time and in-situ detection of produced gas in electrochemical components such as lithium ion secondary batteries and the like.

Description

Technical Field

[0001] This application relates to the fields of batteries and chemical analysis, specifically to electrochemical component detection devices and detection methods. Background Technology

[0002] During operation, electrochemical devices such as lithium-ion batteries generate gases due to the decomposition of components like the electrolyte. The type and amount of gas produced have a significant impact on battery safety, and the type and timing of gas generation are also crucial for monitoring the battery's operation. Therefore, with the deepening of research on lithium-ion batteries, the gas generation situation has attracted increasing attention from researchers.

[0003] However, current analytical techniques are not yet readily available for real-time monitoring of gas generation in electrochemical components such as lithium-ion batteries. Therefore, current detection devices and methods for electrochemical components still require improvement. Summary of the Invention

[0004] In view of the above problems, this application provides an apparatus and method for testing electrochemical components using Raman spectroscopy, which can realize in-situ detection of gas generation in the battery during charging and discharging.

[0005] In one aspect, this application provides an electrochemical component testing device. This device includes a Raman spectroscopy unit and a gas detection unit. The gas detection unit includes an interconnected fiber optic gas sensor and a gas pipeline. The Raman spectroscopy unit is configured to emit light to illuminate the fiber optic gas sensor. The gas pipeline supplies gas generated by the electrochemical component to the fiber optic gas sensor and then returns it to the electrochemical component. This device enables real-time, in-situ detection of gas generation in electrochemical components such as lithium-ion secondary batteries.

[0006] In some embodiments, the gas pipeline has a gas generation inlet and a gas generation return outlet. A first gas valve is provided between the gas generation inlet and the fiber optic gas sensor, and a second gas valve is provided between the gas generation return outlet and the fiber optic gas sensor. The gas pipeline forms a gas loop between the fiber optic gas sensor, the gas generation inlet, and the gas generation return outlet. This further improves the gas detection effect.

[0007] In some embodiments, the fiber optic gas sensor has an internal airflow channel that is connected to the gas circuit. This further improves the gas detection effect.

[0008] In some embodiments, the fiber optic gas sensor is subjected to thermal tapering; and / or the surface of the fiber optic gas sensor is subjected to surface enhancement treatment; and / or the diameter of the fiber optic gas sensor is 50-200 μm. This further improves the gas detection effect.

[0009] In some embodiments, a detachable electrochemical assembly is provided between the gas inlet and the gas return port. In the direction of gas flow, the gas pipeline sequentially includes the electrochemical assembly, the gas inlet, the first gas valve, the fiber optic gas sensor, the second gas valve, and the gas return port. This further improves the gas detection effect.

[0010] In some embodiments, the device further includes a standard gas inlet, a standard gas outlet, a standard gas branch, and a gas production return branch. In the direction of gas flow, the standard gas inlet is located upstream of the second gas valve, and a third gas valve is located between the standard gas inlet and the gas production return branch. The standard gas outlet is located between the fiber optic gas sensor and the second gas valve, and a fourth gas valve is further located upstream of the standard gas outlet. One end of the standard gas branch is located between the second gas valve and the third gas valve, and the other end is located between the first gas valve and the fiber optic gas sensor. The gas production return branch is located between the fiber optic gas sensor and the second gas valve, and a fifth gas valve is located on the gas production return branch. This further improves the gas detection effect.

[0011] In some embodiments, the device further includes: a sixth gas valve located on a standard gas branch; and / or a gas circulation branch located at both ends of the fiber optic gas sensor; and / or a gas pump disposed on the gas pipeline; and / or a gas pressure sensor located on a removable electrochemical assembly; and / or a gas dryer located between the gas generation inlet and the fiber optic gas sensor; and / or a gas storage chamber located between the fiber optic gas sensor and the gas generation return branch. This further improves the gas detection efficiency.

[0012] In another aspect of this application, a detection method using the aforementioned electrochemical component testing device is proposed. The method includes: connecting the electrochemical component to be tested to a gas pipeline; operating the electrochemical component; and detecting the gas production of the electrochemical component using the fiber optic gas sensor. This method can easily achieve in-situ, real-time detection of gas production from the electrochemical component.

[0013] In some embodiments, in the direction of gas flow, the gas pipeline sequentially includes the electrochemical component, the gas inlet, the first gas valve, the fiber optic gas sensor, the second gas valve, and the gas return port. The gas pipeline also includes a gas pump. The method includes: closing the first and second gas valves; starting the gas pump to create a negative pressure within the gas pipeline; operating the electrochemical component; controlling the opening and closing of the gas valves to connect the electrochemical component and the fiber optic gas sensor; and using the fiber optic gas sensor to acquire the Raman signal of the generated gas for detection. This further improves the gas detection effect.

[0014] In some embodiments, the electrochemical component further includes a standard gas inlet, a standard gas outlet, a standard gas branch, a gas generation return branch, and third to sixth gas valves. The method further includes: closing the first, second, and fifth gas valves; opening the third, fourth, and sixth gas valves; supplying a standard gas of known concentration through the standard gas inlet; acquiring the Raman signal of the gas using the fiber optic gas sensor; and repeatedly acquiring the Raman signal by changing the concentration to plot a standard curve of the standard gas. This can further improve the gas detection effect.

[0015] In some embodiments, detecting the gas generated by the electrochemical component includes: acquiring the Raman signal of the generated gas and decoupling the Raman signal to obtain the Raman spectra of different gases in the generated gas; and determining the concentration of the different gases according to the standard curve of the gas. This can further improve the gas detection effect. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0017] Figure 1 This is a schematic diagram of the structure of an electrochemical component testing device according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the structure of an electrochemical component testing device according to another embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the structure of an electrochemical component testing device according to another embodiment of this application;

[0020] Figure 4 The Raman curves for measuring the H2 standard curve in this embodiment of the application;

[0021] Figure 5 The Raman curves for measuring the CO2 standard curve in the embodiments of this application are shown.

[0022] Figure 6 The Raman curves for measuring the C2H4 standard curve in the embodiments of this application;

[0023] Figure 7 The Raman curves for measuring the CO2 standard curve in the embodiments of this application are shown.

[0024] Figure 8 The Raman curves for measuring the C2H2 standard curve in the embodiments of this application are shown.

[0025] Figure 9 The Raman curve for measuring the CO standard curve in the embodiments of this application;

[0026] Figure 10 This is a bar chart showing the gas concentration measured in an embodiment of this application. Detailed Implementation

[0027] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0031] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0032] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0034] As mentioned earlier, the gas generation behavior of electrochemical components such as lithium-ion secondary batteries is of great significance for studying electrolyte behavior during battery operation, as well as battery safety and lifespan. However, the gas generation behavior of these components is mostly intermittent during operation, and the amount of gas generated in the early stages of battery operation is low. Therefore, existing detection methods cannot truly achieve real-time, in-situ detection when detecting trace amounts, low concentrations, and intermittent gas generation. Thus, improving the sensitivity of current gas detection methods and organically connecting the detection device and the electrochemical component in series could significantly alleviate or even solve the aforementioned technical problems. Raman spectroscopy, due to its high sensitivity, good linear relationship between Raman scattering intensity and scatterer concentration, and minimal sample damage during detection, is widely used for the quantitative analysis of gas samples.

[0035] Currently, Raman spectroscopy equipment and methods used for gas sample detection often employ sensor integration within the battery cell to detect gas generation in order to improve detection sensitivity. However, this method can damage the battery cell, and the built-in sensor can also affect the internal interface of the cell, thus impacting the battery's gas generation behavior and preventing true in-situ detection. Furthermore, the gradual increase in gas pressure during cell testing can lead to electrolyte splashing and other problems, further damaging the Raman spectroscopy results.

[0036] This application, by employing a fiber optic gas sensor and through the gas path configuration of the gas detection unit, enables real-time, in-situ detection of gas generation in the electrochemical component without damaging its structure.

[0037] In one aspect, this application provides an electrochemical component testing device. (Reference) Figure 1 The electrochemical component testing device includes a Raman spectroscopy unit 100 and a gas detection unit 200. The gas detection unit 200 includes an interconnected fiber optic gas sensor 210 and a gas pipeline 230. The Raman spectroscopy unit 100 emits light to illuminate the fiber optic gas sensor 210, and may include, for example, a Raman light source (not shown in the figure, the Raman light source is positioned such that the emitted light can illuminate the fiber optic gas sensor 210). The gas pipeline 230 supplies the gas generated by the electrochemical component to the fiber optic gas sensor 210 and then returns it to the electrochemical component. This device, employing a high-resolution fiber optic gas sensor 210 and the configuration on the gas pipeline 230, enables in-situ, real-time detection of gas generation outside the electrochemical component, such as the battery cell.

[0038] In some embodiments, the gas pipeline 230 may have a gas generation inlet 11 and a gas generation return port 12. A first gas valve 1 is provided between the gas generation inlet 11 and the fiber optic gas sensor 210, and a second gas valve 2 is provided between the gas generation return port 12 and the fiber optic gas sensor 210. The gas pipeline 230 forms a gas loop between the fiber optic gas sensor 210, the gas generation inlet 11, and the gas generation return port 12. During testing, an electrochemical component 220, such as a battery, is connected to the gas pipeline 230. The gas generated by the electrochemical component 220 flows into the gas pipeline 230 through the gas generation inlet 11, generates a Raman signal through the fiber optic gas sensor 210, and flows back into the electrochemical component 220 through the gas generation return port 12. This further improves the control of the gas generation inlet 11 and the gas generation return port 12, thereby improving the effectiveness of in-situ detection using this method.

[0039] In some embodiments, the fiber optic gas sensor 210 has an internal gas flow channel that is connected to the gas circuit 230. For example, the fiber optic gas sensor 210 can be formed using an optical fiber with an internal cavity, the cavity acting as a gas flow channel and connected to the gas circuit 230. The cavity may have a sleeve outside capable of light transmission, thereby enabling the interaction between the laser emitted by the Raman source and the gas to be measured within the cavity. The Raman signal generated after the interaction with the gas to be measured is transmitted to the Raman spectroscopy unit 100 to convert the Raman signal into an electrical signal and output a Raman spectrum. The interaction between the laser source and the gas to be measured at the fiber optic gas sensor 210 avoids interference from sample signals caused by electrolyte splashing, which is common with built-in sensors, thus further improving the accuracy and sensitivity of gas detection.

[0040] In some embodiments, the Raman spectroscopy unit 100 may further include a Raman spectrometer and a control unit connected to the Raman spectrometer.

[0041] Raman spectrometer

[0042] In this application, the Raman spectrometer can be a commercially available spectrometer capable of performing Raman spectral analysis on a sample. Specifically, the Raman spectrometer may include a light source, an optical system, and a spectroscopic system. The light source can be a laser source, such as an argon-ion laser or a diode laser. The optical system is used to focus, diffract, and disperse the light beam emitted from the light source, and may include optical elements such as lenses, mirrors, and gratings. The spectroscopic system may include gratings or other diffractive optical elements for separating and / or selecting the scattered light for spectral analysis. For example, the Raman spectrometer may include components such as an objective lens (OL) and a laser power meter (PM).

[0043] Raman scattering

[0044] The frequency difference between the incident light beam and the scattered light produced after its interaction with the sample is also called the Raman shift. The Raman shift is independent of the incident light frequency and depends only on the structure of the scattering molecule itself. Raman scattering is caused by changes in molecular polarizability (changes in the electron cloud). The Raman shift depends on changes in molecular vibrational energy levels. Different chemical bonds or groups have characteristic molecular vibrations, and changes in the molecular vibrational energy level ΔE can reflect changes in a specific energy level. Therefore, the corresponding Raman shift also corresponds to the chemical bond or group. Thus, Raman spectroscopy can serve as a basis for molecular structure analysis.

[0045] controller

[0046] The controller can be a computer or similar device connected to the Raman spectrometer and equipped with data processing capabilities. In this application, the controller may also include software for controlling the operation of the Raman spectrometer, as well as a data processing system capable of processing the signals collected by the spectrometer. The controller can control the opening and closing of the Raman spectrometer's light source, set the spectral scanning frequency range and output power, and output the Raman spectrum using the data processing system via software installed on the computer.

[0047] In some embodiments, the fiber optic gas sensor 210 may be thermoplastic tapered. Thermoplastic tapering enables the focusing of Raman signals. Thermoplastic tapering can be achieved using a process familiar to those skilled in the art. This further reduces production costs.

[0048] To further improve the gas detection performance of this device, the surface of the fiber optic gas sensor 210 can also be surface-enhanced. For example, the fiber optic gas sensor 210 can be surface-enhanced Raman scattering (SERS). This enhances and amplifies the Raman signal, thereby increasing the minimum detection concentration. For example, the surfaces of the transmitting and receiving optical fibers can be modified with nano-gold or nano-silver particles. The laser-excited resonance driving surface charge of the roughened metal nanostructure can generate a highly localized light field, enhancing the intensity of the Raman signal. This improves the accuracy of the device in detecting gas generated by electrochemical components and lowers the detection limit, enabling in-situ analysis of trace gas components.

[0049] In some embodiments, the diameter of the fiber optic gas sensor 210 can be 50-200 μm. For example, fiber optics with diameters of 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, or 500 μm can be used to form the fiber optic gas sensor 210. In some specific embodiments, 100-150 μm, such as 120 μm, fiber optics can be used as the fiber optic gas sensor 210. The fiber optic gas sensor can be a photonic crystal fiber (PCF). When the diameter of the fiber optic gas sensor meets the above requirements, the size of the internal cavity of the fiber optic gas sensor is relatively moderate, which can provide sufficient detection space for Raman laser to enhance the detection signal. At the same time, it can also prevent the detection "dead volume" from increasing due to the increase in the gas path volume in the detection device, which would make it difficult to detect trace amounts of gas.

[0050] In this application, "dead volume" is used to measure the fixed void volume within the gas pipeline 230. This volume is the total gas volume within the complete gas loop formed from the gas inlet 11, through the fiber optic gas sensor 210, back to the gas return port 12 during the detection process.

[0051] In some embodiments, in order to minimize dead volume, the air passages and valve bodies may be selected with smaller dimensions or inner diameters.

[0052] In some embodiments, a removable electrochemical assembly is provided between the gas production inlet and the gas production return outlet, such as... Figure 1The electrochemical component 220 shown is described in this application. In this application, the electrochemical component 220 can be a stacked battery, a pouch battery, a hard-shell battery, etc. Alternatively, the electrochemical component 220 can also be a component capable of completing a charge-discharge process or a corresponding electrochemical oxidation-reduction process, and may or may not have encapsulation structures. In the direction of gas flow, the gas pipeline 230 sequentially includes the electrochemical component 220, a gas generation inlet 11, a first gas valve 1, a fiber optic gas sensor 210, a second gas valve 2, and a gas generation return port 12. The gas generated by the gas pipeline 230 is supplied from the gas generation inlet 11 to the fiber optic gas sensor 210 for detection. Since Raman detection causes almost no damage to the gas sample, the gas treated by the laser can be supplied back to the electrochemical component 220 through the gas generation return port 12, preventing the outflow of the generated gas from affecting the electrochemical activity of the electrochemical component 220. The first gas valve 1 and the second gas valve 2 can control the opening and closing of the gas inlet 11 or the gas return port 12, thereby enabling more flexible control and maintaining the relative independence of the internal environment of the electrochemical component 220 when no detection is required.

[0053] In some embodiments, to further improve the in-situ gas detection performance of the device, the device may further include components for calibrating Raman spectra using standard gases. The components for calibrating Raman spectra using standard gases may include an inlet capable of supplying standard gases of known concentrations (such as H2, CO, CO2, and CH4) to the fiber optic gas sensor 210 for standard gas calibration, as well as pipes, outlets, gas valves, etc., forming a standard gas flow loop. These components can form a standard gas loop within the device and control the standard gas to pass through this loop and through the fiber optic gas sensor 210 during calibration, thereby obtaining Raman signals of standard gases at different known concentrations and realizing the plotting of standard curves corresponding to the concentration-Raman intensity of the standard gases.

[0054] Specifically, refer to Figure 2The device further includes a standard gas inlet 13, a standard gas outlet 14, a standard gas branch 231, and a gas production return branch 232. In the direction of gas flow (as indicated by the arrow in the figure), the standard gas inlet 13 can be located upstream of the gas production return port 12, and a third gas valve 3 is located between the standard gas inlet 13 and the gas production return port. The standard gas outlet 14 is located between the fiber optic gas sensor 210 and the second gas valve 2, and a fourth gas valve 4 is further located upstream of the standard gas outlet 14. One end of the standard gas branch is located between the second gas valve 2 and the third gas valve 3, and the other end is located between the first gas valve 1 and the fiber optic gas sensor 210. To ensure real-time, in-situ detection of gas production from the electrochemical component 220 while adding the standard gas branch 231, the device can further include a gas production return branch 232. The gas production return branch 232 can be located between the fiber optic gas sensor 210 and the second gas valve 2, and a fifth gas valve 5 is located on the gas production return branch 232.

[0055] When a standard curve for the corresponding gas is required, the first gas valve 1 and the second gas valve 2 can be closed first to protect the electrochemical component 220 from the impact of the standard gas flow. Then, by opening the third gas valve 3 and the fourth gas valve 5 and closing the fifth gas valve 5, the gas from the standard gas inlet 13 is allowed to enter the gas path, while simultaneously cutting off the connection between the standard gas and the gas generation return branch 232, allowing it to flow out from the standard gas outlet 14. This allows the acquisition of the standard gas Raman signal and reduces the volume of the gas circuit through which the standard gas flows in the device, thereby further improving the detection effect of the standard gas.

[0056] In some embodiments, by closing the third and fourth gas valves and opening the first, second, and fifth gas valves, in-situ detection of gas production from the electrochemical component 220 can be performed.

[0057] In some embodiments, reference Figure 3The device may further include at least one of the following components: a sixth gas valve 6, a gas circulation branch 233, a gas pump 240, a gas dryer 260, and a gas storage chamber 250. For example, the sixth gas valve 6 may be located on the standard gas branch 231, thereby further improving the control of each branch, reducing the dead volume of detection, and improving the efficiency and effect of gas detection. The gas circulation branch 233 may be located at both ends of the fiber optic gas sensor 210 to enhance the circulation of airflow within the fiber optic gas sensor 210, thereby enhancing the detection signal. The gas pump 240 may be located at any position in the gas pipeline to provide negative pressure within the gas pipeline when the gas production of the electrochemical component 220 is small. The gas dryer 260 may be used to dry the gas produced by the electrochemical component 220. The dried gas entering the fiber optic gas sensor 210 can prevent volatile electrolyte from being introduced into the fiber optic gas sensor 210, causing Raman signal interference. The gas dryer 260 may be located between the first gas valve 1 and the fiber optic gas sensor 210. As mentioned earlier, gas production in the electrochemical component 220 is not necessarily a continuous process. Therefore, a pressure sensor (not shown in the figure) can be installed on the electrochemical component 220 to assist in monitoring the internal pressure. This pressure monitoring can be used to determine whether the lack of gas production inside the electrochemical component 220 is due to insufficient Raman signal detection when the first and second gas valves are open, and the fiber optic gas sensor 210 cannot detect a Raman signal. Alternatively, when the fiber optic gas sensor 210 detects a Raman signal, the state of the device can be determined by observing whether the Raman signal intensity and the pressure of the pressure sensor increase or decrease synchronously. When the pressure of the pressure sensor increases, it indicates that gas production inside the electrochemical component 220 has increased, and the Raman signal should increase accordingly.

[0058] In summary, this device can easily achieve real-time, in-situ detection of gas generation inside electrochemical components such as lithium-ion batteries. Through the design of the gas path and valve body, it can further realize functions such as standard gas calibration and gas generation detection.

[0059] In another aspect of this application, a method for detecting gas production using the aforementioned electrochemical component testing device is proposed. The method includes: placing the electrochemical component to be tested between a gas production inlet and a gas production return outlet, operating the electrochemical component, and detecting the gas production of the electrochemical component using the fiber optic gas sensor. This method enables simple, real-time, in-situ detection of gas production from the electrochemical component.

[0060] In some embodiments, the standard curves for each gas produced can be obtained before measuring the gas production of the electrochemical component 220. Alternatively, the gas production of the electrochemical component 220 can be measured first, and the corresponding gas standard curves can be obtained according to the specific type of gas produced by the electrochemical component 220.

[0061] Taking the determination of the specific type of gas produced by the electrochemical component 220 as an example, in some embodiments, reference is made to... Figure 2 The gas pipeline sequentially includes an electrochemical component 220, a gas inlet, a first gas valve 1, a fiber optic gas sensor 210, a second gas valve 2, and a gas return port 12. A gas pump (not shown) is also present on the gas pipeline. During gas production testing of the electrochemical component 220, the first, second, third, and fifth gas valves are first closed, and the gas pump is started to create a negative pressure in the gas pipeline, for example, approximately one atmosphere. Then, the electrochemical component 220 is started. Typically, the amount of gas produced in the initial stage of operation of the electrochemical component 220 is small; therefore, the negative pressure created by the gas pump allows the small amount of gas to enter the gas path more smoothly and flow into the fiber optic gas sensor 210. Subsequently, the first, second, and fifth gas valves are opened, and the gas generated inside the electrochemical component 220 enters the fiber optic gas sensor 210. The Raman signal of the gas is obtained through the Raman spectroscopy unit, and the detected gas flows back into the electrochemical component 220 through the fifth gas valve 5 and the gas return branch 232. At this time, the Raman signal is a mixed signal of one or more gas-producing gases. The Raman signal can be decoupled to obtain the Raman spectra of different gases in the gas-producing gases, and the chemical composition of the gas-producing gases can be determined based on the characteristic peaks of the Raman spectra.

[0062] Subsequently, a step of obtaining a standard curve for the gases present in the gas-producing chemical composition can be performed. For example, the first and second gas valves can be closed to isolate the electrochemical component 220, while the third and fourth gas valves can be opened, allowing the corresponding standard gas to flow in from the standard gas inlet 13, be sensed and detected by the fiber optic gas sensor 210, and then flow out from the standard gas outlet 14. In some embodiments, to further enhance the detection effect and reduce the dead volume of the gas path, the fifth gas valve 5 can be closed simultaneously with the opening of the third and fourth gas valves.

[0063] Standard gases can be gases with a specific concentration mixed in an inert carrier gas such as argon, such as H2, CO, CO2, CH4, etc., with known concentrations. For example, when plotting a standard curve for H2, the process of introducing H2 gas at a known concentration can be repeated multiple times to obtain multiple Raman spectra. Based on the peak intensities of the characteristic Raman peaks of H2 and their corresponding H2 gas concentrations, a standard curve for H2 gas can be obtained. Subsequently, standard curves for other components in the produced gas can be plotted to determine the content of the corresponding components in the produced gas.

[0064] In some embodiments, the step of obtaining the standard gas curve can also be performed before determining the gas-producing components of the electrochemical component 220. Since the types of gases produced by some electrochemical components 220 are relatively fixed, the aforementioned step of obtaining the standard gas curve can be performed first.

[0065] In some embodiments, after the electrochemical component 220 has been running for a period of time and the gas production has stabilized, the generated gas can be detected directly without undergoing the process of extracting negative pressure within the gas path. Specifically, the gas pressure within the gas path can be 0-1 MPa when the gas production reaches a stable level. At this time, the third and fourth gas valves can be closed, and the first, second, and fifth gas valves can be opened to circulate the gas production and detect it.

[0066] In some embodiments, reference Figure 3 The device may also include a sixth gas valve 6, a gas circulation branch 233, a gas pump 240, a gas dryer 260, and a gas storage chamber 250. The method may include the following steps:

[0067] In the standard gas calibration procedure, the first, second, and fifth gas valves are closed to isolate the electrochemical component 220, while the third, fourth, and sixth gas valves are opened. The standard gas enters through the third gas valve and then flows into the standard gas branch 231. The gas can circulate within the gas circulation branch 233 and the fiber optic gas sensor 210, exiting through the fourth gas valve 4 and the standard gas outlet 14. The gas dryer 260 in the gas circulation loop further absorbs moisture from the gas to improve detection accuracy, and the gas pump 240 can be shut off at this time. The Raman spectrometer performs Raman spectroscopy detection on the standard gas passing through the fiber optic gas sensor 210 to obtain standard curves for various standard gases.

[0068] The low-pressure detection step is for the electrochemical component 220 when it is just starting to operate, for example, when the electrochemical component 220 is a lithium-ion secondary battery. This stage can be the first charge and discharge process of the battery. At this time, the gas production of the electrochemical component 220 is small. First, the first to fourth gas valves can be closed, and the gas pump 240 can be started to create a negative pressure in the gas path. Then, the third, fourth, and sixth gas valves can be closed, and the first, second, and fifth gas valves can be opened. Under the action of the negative pressure in the gas path, the gas produced by the electrochemical component 220 can more easily enter the gas path and circulate in the gas circulation branch 233 and the fiber optic gas sensor 210. After passing through the gas storage chamber 250, it flows back to the electrochemical component 220 through the gas production return branch 232, maintaining the internal environment of the electrochemical component 220 as an in-situ detection environment. At this time, the Raman spectrum obtained at the fiber optic gas sensor 210 is the mixed spectrum of the gas produced in the initial stage of operation of the electrochemical component 220. After decoupling to determine the specific chemical composition of the gas produced, the production of each component gas at different time periods can be determined by referring to the standard curve.

[0069] The high-pressure detection step involves real-time monitoring of gas production during the stable operation of the electrochemical component 220. For example, when the electrochemical component 220 is a lithium-ion secondary battery, this stage can be the period after the formation of the SEI film, such as during battery cycle testing or gas production detection during the resting phase. At this time, the electrochemical component 220 has a certain amount of gas production, and the pressure in the gas path can be maintained at around 0-1 MPa based on the gas production of the electrochemical component 220. At this time, the gas pump 240 can be disabled, the first and second gas valves can be closed, and the remaining gas valves can be opened to purge the gas path with inert gas to eliminate interference from other gases. The fourth and fifth gas valves are then closed, followed by the third and fourth gas valves, and the first, second, fifth, and sixth gas valves are opened to detect the gas production of the electrochemical component 220.

[0070] As mentioned earlier, the gas production of the electrochemical component 220 may be intermittent. During certain periods, when the gas production of the electrochemical component 220 is insufficient to maintain the circulation of gas in the gas path, the gas pump 240 can be activated to compress the gas in the gas storage chamber 250, providing sufficient gas pressure to the gas path, promoting the flow and detection of the produced gas. Whether the gas production is insufficient can be determined by the consistency between the Raman signal acquired by the fiber optic gas sensor 210 and the value of the pressure sensor at the electrochemical component 220. When the value of the pressure sensor at the electrochemical component 220 continuously increases but the fiber optic gas sensor 210 does not acquire a Raman signal, or the Raman signal intensity does not change significantly, it may be due to a low gas production.

[0071] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0072] The Raman spectrometer used in the following examples is an ATR3200. A commercially available optical fiber with a diameter of 120 micrometers was used, and it underwent thermoforming tapering and surface gold sputtering (SERS) to form an optical fiber gas sensor.

[0073] Determination of standard curves for standard gases

[0074] Different concentrations of standard gas are selected for application such as Figure 3 The system shown demonstrates how the Raman signal changes with concentration. The test uses a 1% standard gas mixture with an inert gas (Ar), ensuring a constant total gas flow rate. By adjusting the ratio of the standard gas to the inert gas at regular intervals, the 1% standard gas can be continuously diluted to different concentration gradients (1%, 0.8%, 0.6%, 0.4%, 0.2%), while simultaneously detecting the Raman signal.

[0075] refer to Figures 4-9 The Raman curves (Raman intensity vs. time) show that the Raman signal intensity obtained by the fiber optic sensor changes accordingly with gas concentration, indicating that the system can be used for gas detection. Based on the obtained Raman spectra, standard curves for H2, CO, CO2, CH4, C2H4, and C2H2 were prepared.

[0076] Cell gas generation measurement

[0077] The manufacturing process of battery cells is as follows:

[0078] Negative electrode sheet manufacturing:

[0079] The negative electrode dispersant is uniformly dispersed in an aqueous solution. The negative electrode conductive agent and negative electrode active material are pre-mixed and added to the above aqueous solution. After stirring for a period of time, the negative electrode binder is added to form a slurry. The slurry is thoroughly stirred, sieved, coated onto a negative electrode current collector, and then rolled and cut to obtain negative electrode sheets for later use.

[0080] Positive electrode sheet production:

[0081] The positive electrode binder and N-methylpyrrolidone are thoroughly mixed, the positive electrode conductive agent is added and stirred thoroughly. After mixing thoroughly, ternary NCM is added as the positive electrode active material. After stirring thoroughly, the mixture is sieved and then coated onto the positive electrode current collector. After rolling and slitting, the positive electrode sheet is obtained for later use.

[0082] Electrolyte: EC and DMC with a volume ratio of 30:70 were used as electrolyte, and 1M LiPF6 was used as lithium salt.

[0083] The coated separator and the positive and negative electrode plates are stacked together, with two separators spaced between the positive and negative electrode plates, and the stacked battery cell is assembled. After liquid injection, the battery is obtained.

[0084] Adopting such Figure 3 The device shown detects gas generation during the charging and discharging process of the battery cell. Before operating the battery cell, the first to fourth gas valves are closed, and the gas pump is started until the gas pressure in the gas path reaches -1 atm. The gas pump is then turned off, while the third and fourth gas valves remain closed, and the sixth gas valve is closed simultaneously. Subsequently, the battery cell is operated while the first, second, and fifth gas valves are opened. Raman spectroscopy is then used, and a fiber optic gas sensor receives the gas Raman signal. The Raman signals at times t1 and t2 are captured for analysis.

[0085] Based on the detected Raman signals, the mixed gas signals were decoupled to obtain the Raman spectra of different gases, and the content of each gas was determined according to the Raman signal intensity. The types of gases produced and the percentage of each gas produced (%, with the total gas production at each time being 100%) at times t1 and t2 are shown in Table 1 below. The bar charts for the percentage of each gas produced at times t1 and t2 are shown below. Figure 10 As shown.

[0086] Table 1

[0087]

[0088] Refer to Table 1 above and Figure 10 It can be seen that the device and method can detect the gas production of the battery cell in real time, monitor the amount of gas produced by the battery cell at different times, and distinguish the content of multiple components. This shows that the method and device have sufficient detection sensitivity and low detection limit, and can reflect the differences in gas production of the battery cell at different times.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrochemical component testing device, characterized in that, Includes Raman spectroscopy unit and gas detection unit, The gas detection unit includes interconnected fiber optic gas sensors and gas pipelines. The Raman spectroscopy unit is configured to emit light to illuminate the fiber optic gas sensor. The gas pipeline is used to supply the gas generated by the electrochemical component to the fiber optic gas sensor and then return it to the electrochemical component.

2. The electrochemical component testing device according to claim 1, characterized in that, The gas pipeline has a gas production inlet and a gas production return outlet. A first gas valve is located between the gas production inlet and the fiber optic gas sensor, and a second gas valve is located between the gas production return outlet and the fiber optic gas sensor. The gas pipeline forms a gas loop between the fiber optic gas sensor, the gas inlet, and the gas return port.

3. The electrochemical component testing device according to claim 1 or 2, characterized in that, The fiber optic gas sensor has an internal airflow channel, which is connected to the gas circuit.

4. The electrochemical component testing apparatus according to any one of claims 1-3, characterized in that, The fiber optic gas sensor is heat-fused tapered; and / or The surface of the fiber optic gas sensor is surface-enhanced; and / or The diameter of the fiber optic gas sensor is 50-200μm.

5. The electrochemical component testing apparatus according to any one of claims 2-4, characterized in that, A detachable electrochemical assembly is provided between the gas production inlet and the gas production return outlet. In the direction of gas flow, the gas pipeline sequentially includes the electrochemical component, the gas production inlet, the first gas valve, the fiber optic gas sensor, the second gas valve, and the gas production return port.

6. The electrochemical component testing apparatus according to claim 5, characterized in that, It further includes a standard gas inlet, a standard gas outlet, a standard gas branch, and a gas production return branch. In the direction of gas flow, the standard gas inlet is located upstream of the second gas valve, and a third gas valve is located between the standard gas inlet and the gas production return port. The standard gas outlet is located between the fiber optic gas sensor and the second gas valve, and a fourth gas valve is further located upstream of the standard gas outlet. One end of the standard gas branch is located between the second gas valve and the third gas valve, and the other end is located between the first gas valve and the fiber optic gas sensor. The gas production return branch is located between the fiber optic gas sensor and the second gas valve, and the gas production return branch has a fifth gas valve.

7. The electrochemical component testing apparatus according to any one of claims 1-6, characterized in that, Further includes: A sixth gas valve, said sixth gas valve being located on a standard gas branch; and / or A gas circulation branch, wherein the gas circulation branch is located at both ends of the fiber optic gas sensor; and / or An air pump, wherein the air pump is disposed on the gas pipeline; and / or A pressure sensor, said pressure sensor being located on a detachable electrochemical assembly; and / or A gas dryer is located between the gas inlet and the fiber optic gas sensor. and / or A gas storage chamber is located between the fiber optic gas sensor and the gas production return branch.

8. A method for detection using the electrochemical component testing apparatus according to any one of claims 1-7, characterized in that, include: Connect the electrochemical component to be tested and the gas pipeline; The electrochemical component is operated, and the gas production of the electrochemical component is detected using the fiber optic gas sensor.

9. The method according to claim 8, characterized in that, In the direction of gas flow, the gas pipeline sequentially includes the electrochemical component, the gas production inlet, the first gas valve, the fiber optic gas sensor, the second gas valve, and the gas production return port. The gas pipeline has a gas pump, and the method includes: Close the first and second gas valves, and start the gas pump to create negative pressure in the gas pipeline; The electrochemical component is operated to control the opening and closing of the gas valve, thereby connecting the electrochemical component and the fiber optic gas sensor. The Raman signal of the generated gas is obtained using the fiber optic gas sensor to detect the generated gas.

10. The method according to claim 8 or 9, characterized in that, The electrochemical assembly further includes a standard gas inlet, a standard gas outlet, a standard gas branch, a gas production reflux branch, and third to sixth gas valves; the method further includes: Close the first, second, and fifth gas valves, open the third, fourth, and sixth gas valves, and supply standard gas of known concentration through the standard gas inlet. Use the fiber optic gas sensor to acquire the Raman signal of the standard gas, and repeat the acquisition of the Raman signal multiple times by changing the concentration to plot the standard curve of the standard gas.

11. The method according to claim 10, characterized in that, Detection of the gas generated by the electrochemical component includes: The Raman signal of the produced gas is acquired, and the Raman signal is decoupled to obtain the Raman spectra of different gases in the produced gas. The concentrations of the different gases are determined based on the standard curve of the gases.

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