In-situ monitoring method for battery chemical stress

Abstract

The present invention provides a method for in-situ monitoring of chemical stress in a battery, comprising: arranging a sensing optical fiber in a serpentine pattern in a first direction over the surface of a battery's anode plate, completely covering the anode plate; connecting each adjacent first optical fiber segment via a corresponding second optical fiber segment; securing the ends of each first optical fiber segment, located outside the anode plate, to a protective casing beneath the anode plate, such that each first optical fiber segment remains stretched during monitoring; connecting the sensing optical fiber to a strain measurement and analysis system, performing a pressure test on each end of each first optical fiber segment to calibrate its position; and obtaining a three-dimensional strain field of the anode plate based on scattered signals transmitted back from each first optical fiber segment, the calibrated positions of the ends of each first optical fiber segment, and the layout relationship between the first optical fiber segments. The present invention can monitor the strain field of the entire surface of the anode plate.

Description

Technical Field

[0001] The present invention belongs to the field of optical fiber sensing, and in particular relates to a method for in-situ monitoring of battery chemical stress. Background Art

[0002] In recent years, the field of new energy-driven electric vehicles has become a global focus. Lithium-ion batteries (Li-ion batteries) have become a key research area due to their high energy density, high efficiency, and environmental friendliness. Furthermore, they have widespread applications in portable electronic devices, energy storage systems, and medical devices. However, these advances come with challenges in the research, testing, and use of Li-ion batteries, which necessitate a focus on the internal workings of the battery. Understanding these issues is crucial for gaining a deeper understanding of battery operation and effectively managing battery systems. The choice of anode material is crucial for influencing the performance of Li-ion batteries, and silicon-containing anode materials are the preferred choice for high-capacity batteries. However, their significant expansion poses challenges to cycling and lifespan. As batteries undergo cyclic charge and discharge, the anode material may experience residual strain, impacting its long-term stability and performance. Therefore, strain monitoring of batteries is crucial for predicting their operating state. To date, no effective method exists for distributed in-situ monitoring within Li-ion batteries. Summary of the Invention

[0003] The present invention provides a battery chemical stress in-situ monitoring method to solve the current problem that the strain field of the battery anode plate cannot be reconstructed in a distributed real-time manner.

[0004] According to a first aspect of an embodiment of the present invention, a method for in-situ monitoring of chemical stress in a battery is provided, comprising: step S100, routing a sensing optical fiber in a serpentine manner in a first direction to cover the upper surface of an anode plate of a battery, wherein each time the sensing optical fiber is bent and routed in a second direction, a first optical fiber segment is formed, and each adjacent two first optical fiber segments are connected by a corresponding second optical fiber segment, and the first direction is perpendicular to the second direction;

[0005] Step S200: For each first optical fiber segment, fixing the two ends of the first optical fiber segment outside the anode plate to the protective shell below the anode plate, so that the first optical fiber segment is subjected to corresponding prestressing force to ensure that the first optical fiber segment remains in a stretched state during the monitoring process;

[0006] Step S300: Connect one end of the sensing optical fiber to a strain measurement and analysis system, and perform a pressure test on both ends of each first optical fiber segment to calibrate the position of each first optical fiber segment;

[0007] Step S400: The strain measurement and analysis system determines the strain amount at each measurement point on the first optical fiber segment based on the scattered signal transmitted back by each first optical fiber segment and the calibrated positions of both ends of the first optical fiber segment; reconstructs the two-dimensional strain field of the first optical fiber segment based on the strain amount at each measurement point on the first optical fiber segment; and obtains the three-dimensional strain field of the anode plate composed of the two-dimensional strain fields of the first optical fiber segments based on the layout relationship between the first optical fiber segments.

[0008] In an optional implementation, when the battery is charged and discharged, the anode plate undergoes a chemical reaction, causing the anode plate to shrink or expand, thereby causing the first optical fiber segment covered on the anode plate to be compressed or stretched axially, generating axial strain of the optical fiber.

[0009] In another optional implementation, the anode plate, the isolation layer and the cathode plate are sequentially arranged on the protective shell from top to bottom.

[0010] In another optional implementation, the second optical fiber segment is laid on the protective shell under the anode plate. In the step S400, before reconstructing the two-dimensional strain field of the first optical fiber segment according to the strain at each measurement point on the first optical fiber segment, it also includes: the strain measurement and analysis system determines the strain of the second optical fiber segment based on the scattered signal transmitted back by each second optical fiber segment and the calibrated two end positions of the first optical fiber segment; determines the corresponding temperature of the second optical fiber segment according to the strain of the second optical fiber segment; adds the temperatures of each second optical fiber segment and takes an average value to obtain the average temperature of the battery; converts the average temperature into the corresponding strain; and subtracts the strain corresponding to the average temperature from the strain at each measurement point on the first optical fiber segment.

[0011] In another optional implementation, each second optical fiber segment completely covers the protective shell on the corresponding side in the second direction, and the lengths of the second optical fiber segments are equal.

[0012] In another optional implementation, the method further includes: determining the thickness uniformity of the anode plate according to the three-dimensional strain field of the anode plate.

[0013] In another optional implementation, the method further includes: determining the adaptability of the manufacturing process for manufacturing anode plates of different materials based on thickness uniformity of anode plates of different materials manufactured under the corresponding manufacturing process.

[0014] In another optional implementation, the method further includes: for anode plates made of different materials, taking the anode plate made of the corresponding material with the smaller strain amount corresponding to the initial three-dimensional strain field as the anode plate with better performance.

[0015] In another optional implementation, the method further includes: for each anode plate of different materials, with time as the horizontal coordinate and the sum of the strain quantities of each first optical fiber segment relative to its initial state as the vertical coordinate, drawing a trend curve of the change of the sum of the strain quantities over time; determining the time when the slope of the curve decreases and the slope of the curve after the decrease in the change trend curve; determining the initial slope of the change trend curve; based on the change trend curves corresponding to the anode plates of different materials, screening out the anode plates of the corresponding materials with a higher initial slope, a later time when the curve slope decreases, and a higher slope after the decrease as the anode plates with better performance.

[0016] In another optional implementation, the sum of the strain amounts is: first, for each first optical fiber segment, the strain amounts of each measurement point on the first optical fiber segment relative to its initial state are added to obtain the strain amounts of each first optical fiber segment relative to its initial state; and then the strain amounts of each first optical fiber segment relative to its initial state are added.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention covers the anode plate of a battery with a sensing optical fiber in a first direction and a second direction perpendicular to the first direction. This allows monitoring of the strain of the entire anode plate, thereby determining the uniformity of the corresponding material anode plate. The anode plate material or manufacturing process can be adjusted based on the uniformity, and a more optimal anode plate material can be selected based on the overall change in the strain of the corresponding material anode plate during use. When arranging a first optical fiber segment directly above the anode plate, the ends of the first optical fiber segment are respectively fixed to a protective shell below the anode plate, and a prestress is applied to the first optical fiber segment, so that the first optical fiber segment remains in a stretched state during monitoring. Only in this way can the first optical fiber segment accurately detect the deformation of the anode plate during monitoring. The present invention can reconstruct the three-dimensional strain field of the anode plate based on the calibrated positions of the two ends of each first optical fiber segment, the scattered signals transmitted back by each first optical fiber segment, and the layout relationship between the first optical fiber segments. The present invention implants the sensing optical fiber into the battery, achieving in-situ monitoring without affecting battery performance. In addition, the present invention adopts distributed monitoring. Compared with single-point sensors, it can obtain the strain field of the entire surface of the lithium battery anode material instead of strain information at a single point, which has higher reliability.

[0019] 2. The present invention uses the sum of the strains at all measurement points on the second optical fiber segment as the strain of the second optical fiber segment. The corresponding temperature of the second optical fiber segment is determined by establishing a relationship between the strain of the second optical fiber segment and the temperature. Since the strain of the second optical fiber segment is large, the accuracy of reflecting its temperature based on the strain of the second optical fiber segment is higher. After determining the temperature of each second optical fiber segment, the temperatures of each second optical fiber segment are added and then divided by the number of second optical fiber segments to obtain the average temperature of the battery. The accuracy of the average battery temperature obtained in this way is also high. The present invention subtracts the strain caused by the average battery temperature from the strain detected on the first optical fiber segment to accurately obtain the strain caused by the deformation of the anode plate on the first optical fiber segment, thereby improving the accuracy of the reconstruction of the three-dimensional strain field of the anode plate.

[0020] 3. The present invention ensures that each second optical fiber segment completely covers the protective shell on the corresponding side in the second direction. Since the contact length between the second optical fiber segment and the protective shell is longer, it is easier for heat to reach thermal equilibrium quickly, reducing the difference in the impact of temperature on the first and second optical fiber segments. The present invention ensures that the lengths of the second optical fiber segments are equal, so that a unified standard can be used to determine the corresponding temperature of the second optical fiber segment based on the relationship between the strain of the second optical fiber segment and the temperature.

[0021] 4. The present invention can determine the thickness uniformity of the anode plate based on the three-dimensional strain field of the anode plate. Based on the thickness uniformity of the anode plate, the anode plate material corresponding to the manufacturing process or the manufacturing process corresponding to the anode plate material can be selected;

[0022] 5. The present invention uses anode plates made of different materials, and selects the anode plate with the smaller initial three-dimensional strain field as the anode plate with better performance. This can avoid excessive strain causing cracking of the anode material, which affects the battery life.

[0023] 6. The present invention monitors the three-dimensional strain field of the anode plate in real time and draws a curve reflecting the overall strain change trend of the anode plate, thereby screening out anode plates of corresponding materials with better performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of an embodiment of the method for in-situ monitoring of battery chemical stress of the present invention;

[0025] Figure 2 This is a layout diagram of the sensing optical fiber of the present invention;

[0026] Figure 3 is a cross-sectional view of the arrangement of the sensing optical fiber of the present invention;

[0027] Figure 4 Schematic diagram of the three-dimensional strain field reconstruction of the anode plate of the present invention;

[0028] Figure 5 It is a schematic structural diagram of an embodiment of the battery chemical stress in-situ monitoring system of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0030] In the description of the present invention, unless otherwise specified and limited, it should be noted that the term "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two elements. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meaning of the above terms can be understood according to the specific circumstances.

[0031] See also Figure 1 , is a flow chart of an embodiment of the battery chemical stress in-situ monitoring method of the present invention. Figures 2 to 4 As shown, the method may include:

[0032] Step S100: The sensing optical fiber is serpentine-routed in the first direction to cover the upper surface of the anode plate 2 of the battery, and each time the sensing optical fiber 1 bends and routes along the second direction, it is the first optical fiber segment 11, and each adjacent two first optical fiber segments 11 are connected by the corresponding second optical fiber segment 12, and the first direction is perpendicular to the second direction.

[0033] In this embodiment, the first direction can be the length direction of the anode plate 2, and the second direction can be the width direction of the anode plate 2. The sensing optical fiber is composed of a plurality of first optical fiber segments 11 parallel to the second direction and spaced apart, and a plurality of second optical fiber segments 12 for connecting adjacent first optical fiber segments. The first optical fiber segments 12 completely cover the anode plate in the second direction (i.e., the width direction of the anode plate), and the spacing of the mutually parallel second optical fiber segments 12 is greater than 1 mm. The second optical fiber segments 12 are located on both sides of the anode plate 2, and the second optical fiber segments 12 on both sides can be staggered. The sensing optical fiber can be encapsulated in the protective shell of the battery along with the anode plate 2. The sensing optical fiber should have a high-temperature resistant coating, such as a polyimide coating, a gold coating, etc., to ensure that the optical fiber to be measured will not break when the battery is encapsulated. When the battery is charged and discharged, the anode plate 2 will undergo a chemical reaction, causing the anode plate to shrink or expand, thereby causing the first optical fiber segment covering the anode plate to be compressed or stretched in the axial direction of the optical fiber, generating axial strain of the optical fiber.

[0034] Step S200: For each first optical fiber segment 11, the two ends 13 of the first optical fiber segment 11 located outside the anode plate 2 are respectively fixed to the protective shell 3 under the anode plate 2 (fixation can be carried out using ear glue, etc.), so that the first optical fiber segment 11 is applied with corresponding prestress to ensure that the first optical fiber segment 11 always remains in a stretched state during the monitoring process.

[0035] In this embodiment, combined with Figure 3 As shown, the protective shell 3 is sequentially arranged from top to bottom with the anode plate 2, the separator 4, and the cathode plate 5. Another protective shell may also be arranged above the anode plate 2. The battery may be a lithium battery, and the protective shell 3 may be an aluminum-plastic shell to package the battery and prevent electrolyte leakage. The cathode plate 5 may be a lithium electrode. The separator may be a piece of diaphragm paper, which is used to separate the anode and cathode materials and prevent them from reacting, and to ensure that the anode strain of the lithium battery is not affected by the cathode. The anode plate 3 can be replaced with a variety of different materials, such as a hybrid electrode of silicon monoxide (SiO) and graphite (C).

[0036] Step S300 : Connect one end of the sensing optical fiber to a strain measurement and analysis system, and perform a press test on both ends 13 of each first optical fiber segment 11 to calibrate the position of each first optical fiber segment 11 .

[0037] Step S400, the strain measurement and analysis system can determine the strain amount at each measuring point on the first optical fiber segment 11 based on the scattered signal transmitted back by each first optical fiber segment 11 and the calibrated two-end positions of the first optical fiber segment 11; reconstruct the two-dimensional strain field of the first optical fiber segment 11 based on the strain amount at each measuring point on the first optical fiber segment 11; and obtain the three-dimensional strain field of the anode plate 2 composed of the two-dimensional strain fields of each first optical fiber segment based on the layout relationship between the various first optical fiber segments 11.

[0038] In this embodiment, combined with Figure 5 As shown, the strain measurement and analysis system may include an OFDR system (e.g., a phase-type optical frequency domain reflectometer φ-OFDR) and a data processing device, wherein the OFDR system can detect the axial strain generated on the sensing optical fiber based on the scattered signal transmitted back by the sensing optical fiber, and the data processing unit reconstructs the three-dimensional strain field of the battery based on the detected strain, thereby realizing distributed in-situ monitoring of the anode plate in the battery.

[0039] As can be seen from the above embodiments, the present invention covers the anode plate of the battery with the sensing optical fiber in a first direction and in a second direction perpendicular to the first direction, so that the strain of the entire anode plate can be monitored, thereby determining the uniformity of the anode plate of the corresponding material, adjusting the anode plate material or manufacturing process according to the uniformity, and selecting a better anode plate material according to the overall change in the strain of the anode plate of the corresponding material during use; when the present invention arranges the first optical fiber segment located directly above the anode plate, the two ends of the first optical fiber segment are respectively fixed on the protective shell under the anode plate, and prestress is applied to the first optical fiber segment, so that the first optical fiber segment The segment is always kept in a stretched state during the monitoring process, so that the first optical fiber segment can accurately detect the deformation of the anode plate during the monitoring process; the present invention can realize the three-dimensional strain field reconstruction of the anode plate according to the calibrated two-end positions of each first optical fiber segment, the scattered signals transmitted back by each first optical fiber segment and the layout relationship between each first optical fiber segment; the present invention implants the sensing optical fiber into the battery, which will not affect the battery performance while realizing in-situ monitoring; and the present invention adopts distributed monitoring, which can obtain the strain field of the entire surface of the lithium battery anode material instead of the strain information of a single point position compared with a single-point sensor, and has higher reliability.

[0040] During the battery's charging and discharging process, chemical reactions occur in the anode plate, causing not only deformation but also heat generation. Therefore, the first fiber segment 11 in the sensing fiber will experience strain not only due to the anode plate deformation but also due to temperature. To eliminate temperature interference, the second fiber segment is laid on a protective housing beneath the anode plate. In step S400, before reconstructing the two-dimensional strain field of the first fiber segment based on the strain at each measurement point on the first fiber segment, the following steps may also be performed:

[0041] The strain measurement and analysis system determines the strain of each second optical fiber segment based on the scattered signal transmitted back by the second optical fiber segment and the calibrated positions of the two ends of the first optical fiber segment; determines the corresponding temperature of the second optical fiber segment based on the strain of the second optical fiber segment; adds and averages the temperatures of each second optical fiber segment to obtain the average temperature of the battery; converts the average temperature into the corresponding strain; and subtracts the strain corresponding to the average temperature from the strain at each measurement point on the first optical fiber segment.

[0042] The strain in a sensing fiber affected by temperature is typically small. If, when determining the average battery temperature, the strain at each measurement point on the second fiber segment is summed and then divided by the number of measurement points to obtain the average strain, and the average temperature is determined by establishing a relationship between the average strain and the average temperature, then due to the small average strain, the accuracy of the average temperature reflected based on the average strain is low. However, the present invention uses the sum of the strains at all measurement points on the second fiber segment as the strain of that second fiber segment, and determines the corresponding temperature of the second fiber segment by establishing a relationship between the strain and temperature. Because the strain of the second fiber segment is larger, the accuracy of the temperature reflected based on the strain of the second fiber segment is higher. After determining the temperature of each second fiber segment, the temperatures of each second fiber segment are summed and then divided by the number of second fiber segments to obtain the average battery temperature. This average battery temperature is also highly accurate. The present invention subtracts the strain caused by the average battery temperature from the strain detected on the first fiber segment to accurately obtain the strain caused by the anode plate deformation on the first fiber segment, thereby improving the accuracy of the anode plate three-dimensional strain field reconstruction. In addition, when eliminating the influence of temperature corresponding variable measurement, the present invention establishes two types of corresponding relationships related to temperature. One type of temperature relationship is related to the total strain of the second optical fiber segment and the temperature of the area where the second optical fiber segment is located on the protective shells on both sides under the anode plate. The other type of temperature relationship is related to the average temperature of the protective shells on both sides under the anode plate and the strain of the first optical fiber segment on the anode plate caused by the average temperature. Both of these relationships establish the relationship between the optical fiber and the temperature of the protective shell. The relationship is simple to establish, and when a parameter in one of the relationships changes (for example, the coverage of the corresponding area on the protective shell by the second optical fiber segment, etc.), only the relationship needs to be adjusted without having to re-establish the entire relationship. Therefore, the temperature elimination is more flexible.

[0043] Among them, since the anode plate generates heat during the battery charging and discharging process, the heat can be transferred from the anode plate to the first sensing optical fiber segment and then to the second optical fiber segment on the one hand, and can be transferred to the protective shell through the isolation layer and the cathode layer in sequence for heat dissipation on the other hand. Since the second optical fiber segment is laid on the protective shell, the heat dissipation forms a closed loop path, and the effects of temperature on the first optical fiber segment and its corresponding second optical fiber segment are not much different. The present invention can also make each second optical fiber segment 12 completely cover the protective shell 3 on the corresponding side in the second direction. Since the contact length between the second optical fiber segment and the protective shell is longer, it is easier for the heat to reach thermal equilibrium quickly, reducing the difference in the effects of temperature on the first optical fiber segment and the second optical fiber segment. The lengths of the various second optical fiber segments 12 of the present invention can also be equal, and the shapes of the various second optical fiber segments can also be the same. In this way, a unified standard can be adopted to determine the corresponding temperature of the second optical fiber segment based on the relationship between the strain of the second optical fiber segment and the temperature.

[0044] In addition, combined Figure 4As shown, the method of the present invention may further include: determining the thickness uniformity of the anode plate based on the three-dimensional strain field of the anode plate, and determining the manufacturing qualification rate of the anode plate based on the thickness uniformity. The method of the present invention may further include: determining the suitability of the manufacturing process for manufacturing anode plates of different materials based on the thickness uniformity of anode plates of different materials manufactured under the corresponding manufacturing process. It can be seen that the present invention can determine the thickness uniformity of the anode plate based on the three-dimensional strain field of the anode plate, and based on the thickness uniformity of the anode plate, it can also select the anode plate material corresponding to the manufacturing process or the manufacturing process corresponding to the anode plate material.

[0045] When screening the materials of the anode plates, if the initial three-dimensional strain field corresponds to a large strain value for different anode plate materials, the anode material may crack due to excessive strain, thereby affecting the battery life. Therefore, the method of the present invention may further include: for anode plates of different materials, the anode plate of the corresponding material with a smaller strain value corresponding to the initial three-dimensional strain field is selected as the anode plate with better performance.

[0046] In addition, during the charge and discharge process of the battery, the ions in the battery will continue to move, but as time goes by, some of the ions may no longer move, which will cause the activity of the anode material to become lower and lower, thereby causing the strain to become smaller and smaller. By judging the change trend of the strain, the performance of the anode material can be reflected to a certain extent. To this end, the method of the present invention can also include, for each anode plate of different materials, using time as the horizontal coordinate and the sum of the strains of each first optical fiber segment relative to its initial state as the vertical coordinate, drawing a trend curve of the sum of the strains over time; determining the time when the slope of the curve decreases and the slope of the curve after the decrease in the change trend curve; determining the initial slope of the change trend curve; based on the change trend curve corresponding to each anode plate of different materials, screening out the corresponding material anode plate with a higher initial slope, a later time when the slope of the curve decreases, and a higher slope after the decrease as the anode plate with better performance. It can be seen that the present invention can screen out anode plates of corresponding materials with better performance by real-time monitoring of the three-dimensional strain field of the anode plate and drawing a curve used to reflect the overall strain change trend of the anode plate.

[0047] The sum of the strain amounts can be obtained by: first, for each first optical fiber segment, adding the strain amounts of each measurement point on the first optical fiber segment relative to its initial state to obtain the strain amounts of each first optical fiber segment relative to its initial state; and then adding the strain amounts of each first optical fiber segment relative to its initial state.

[0048] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0049] It will be appreciated that the present invention is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and variations can be made without departing from its scope, which is governed solely by the appended claims.

Claims

1. A method for in-situ monitoring of battery chemical stress, characterized in that: include: Step S100: The sensing optical fiber is serpentine-routed in a first direction to cover the upper surface of the anode plate of the battery. Each time the sensing optical fiber bends and runs in a second direction, it becomes a first optical fiber segment. Every two adjacent first optical fiber segments are connected by a corresponding second optical fiber segment. The first direction is perpendicular to the second direction. Step S200: For each first optical fiber segment, fixing the two ends of the first optical fiber segment outside the anode plate to the protective shell below the anode plate, so that the first optical fiber segment is subjected to corresponding prestressing force to ensure that the first optical fiber segment remains in a stretched state during the monitoring process; Step S300: Connect one end of the sensing optical fiber to a strain measurement and analysis system, and perform a pressure test on both ends of each first optical fiber segment to calibrate the position of each first optical fiber segment; Step S400: The strain measurement and analysis system determines the strain amount at each measurement point on the first optical fiber segment based on the scattered signal transmitted back by each first optical fiber segment and the calibrated positions of both ends of the first optical fiber segment; reconstructs the two-dimensional strain field of the first optical fiber segment based on the strain amount at each measurement point on the first optical fiber segment; and obtains the three-dimensional strain field of the anode plate composed of the two-dimensional strain fields of the first optical fiber segments based on the layout relationship between the first optical fiber segments.

2. The battery chemical stress in-situ monitoring method according to claim 1, characterized in that: When the battery is charged and discharged, the anode plate undergoes a chemical reaction, causing the anode plate to shrink or expand, thereby causing the first optical fiber segment covered on the anode plate to be compressed or stretched in the optical fiber axial direction, generating optical fiber axial strain.

3. The battery chemical stress in-situ monitoring method according to claim 1, characterized in that: The anode plate, the isolation layer and the cathode plate are sequentially arranged on the protective shell from top to bottom.

4. The battery chemical stress in-situ monitoring method according to any one of claims 1 to 3, characterized in that: The second optical fiber segment is laid on the protective housing below the anode plate. In step S400, before reconstructing the two-dimensional strain field of the first optical fiber segment based on the strain values ​​at each measurement point on the first optical fiber segment, the method further includes: The strain measurement and analysis system determines the strain of each second optical fiber segment based on the scattered signal transmitted back by the second optical fiber segment and the calibrated positions of the two ends of the first optical fiber segment; determines the corresponding temperature of the second optical fiber segment based on the strain of the second optical fiber segment; adds and averages the temperatures of each second optical fiber segment to obtain the average temperature of the battery; converts the average temperature into the corresponding strain; and subtracts the strain corresponding to the average temperature from the strain at each measurement point on the first optical fiber segment.

5. The battery chemical stress in-situ monitoring method according to claim 4, characterized in that: Each second optical fiber segment completely covers the protective shell on the corresponding side in the second direction, and the lengths of the second optical fiber segments are equal.

6. The battery chemical stress in-situ monitoring method according to claim 1, characterized in that: The method further includes determining thickness uniformity of the anode plate according to the three-dimensional strain field of the anode plate.

7. The battery chemical stress in-situ monitoring method according to claim 6, characterized in that: The method further includes: determining the adaptability of the manufacturing process for manufacturing anode plates of different materials according to the thickness uniformity of the anode plates of different materials manufactured under the corresponding manufacturing process.

8. The battery chemical stress in-situ monitoring method according to claim 1, 6 or 7, characterized in that: The method further includes: for anode plates made of different materials, taking the anode plate of the corresponding material with the smaller strain amount corresponding to the initial three-dimensional strain field as the anode plate with better performance.

9. The battery chemical stress in-situ monitoring method according to claim 8, characterized in that: The method further includes: for each anode plate of different materials, plotting a trend curve of the sum of the strains over time, with time as the abscissa and the sum of the strains of each first optical fiber segment relative to its initial state as the ordinate; determining the time when the slope of the curve decreases and the slope of the curve after the decrease; and determining the initial slope of the trend curve; According to the change trend curves corresponding to the anode plates of different materials, the anode plates of the corresponding materials with higher initial slope, later decreasing time of the curve slope, and higher slope of the curve after decreasing are selected as the anode plates with better performance.

10. The battery chemical stress in-situ monitoring method according to claim 9, characterized in that: The sum of the strain amounts is as follows: first, for each first optical fiber segment, the strain amounts of each measurement point on the first optical fiber segment relative to its initial state are added to obtain the strain amounts of each first optical fiber segment relative to its initial state; then, the strain amounts of each first optical fiber segment relative to its initial state are added.

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