A single-particle electrode material rate performance characterization method based on optical imaging

Abstract

This invention discloses a method for characterizing the rate performance of single-particle electrode materials based on optical imaging. The method includes constructing an electrochemical testing configuration that allows for optical observation, performing constant current charge-discharge at a controlled rate while simultaneously acquiring optical data, defining rate-related characterization parameters based on the optical data, and evaluating the rate performance of the single-particle electrode material. This method utilizes optical imaging to acquire the real-time response of particles during charge-discharge, enabling quantitative analysis of the rate response at the single-particle scale. It overcomes the problem of averaging particle behavior in macroscopic testing, improving the accuracy and resolution of material performance evaluation. This invention is simple to operate, highly efficient, and suitable for high-throughput, high-spatial-resolution characterization of electrode material rate performance.

Description

Technical Field

[0001] This invention relates to the characterization of electrode material properties, and more specifically to a method for characterizing the rate performance of single-particle electrode materials based on optical imaging. Background Technology

[0002] Rate performance of electrode materials is a crucial indicator for evaluating their charge-discharge capabilities under high-power conditions, directly impacting the actual performance of energy storage devices in applications such as fast charging and pulse discharging. Currently, rate performance is typically assessed by conducting charge-discharge tests on batteries under different rate conditions and comparing their capacity retention or polarization behavior. However, these methods are primarily based on the electrochemical response at the macroscopic electrode or overall battery level. The test results are essentially an average response obtained by superimposing the behaviors of numerous particles, making it difficult to distinguish differences in reaction rates, transport capabilities, and other characteristics among different particles. In actual material systems, particle size, morphology, and defect distribution often exhibit significant differences. Under high-rate conditions, this inter-particle kinetic inhomogeneity is further amplified, but it is averaged out in macroscopic tests, thus masking the true reaction information at the individual particle level within the electrode material.

[0003] In recent years, single-particle electrochemical testing methods have been used to study the reaction behavior of electrode materials, exploring their reaction kinetics by applying electrochemical excitation to individual particles. However, these methods still primarily rely on electrical signals such as current and voltage for characterization. At high magnification or small scales, the current signal amplitude is small and noise is high, making it difficult to obtain stable and repeatable test results, thus limiting their application in rate performance studies. Meanwhile, with the development of optical imaging technology, related research has begun to attempt to introduce optical methods for in-situ observation of the reaction process of single-particle electrode materials, analyzing changes in optical signals to reflect the internal reaction or transport processes of the material. However, existing optical imaging research mostly focuses on the visualization or qualitative analysis of the reaction process; optical signals are usually only used as qualitative or auxiliary information and have not been defined as quantitative indicators that can be used for rate performance evaluation. Furthermore, the test throughput is low, making it difficult to conduct systematic comparisons and statistical characterization of a batch of particles. The test configuration is also unstable; the particle-electrode contact state is easily affected, and the correspondence between optical signals and actual electrochemical states is uncertain. A systematic method that can quantitatively characterize rate performance at the single-particle scale and establish a direct correspondence between optical response and rate-related kinetic characteristics has not yet been developed.

[0004] Therefore, there is an urgent need for a new characterization method that can quantitatively characterize the changes in the internal reaction state of electrode materials under different rate conditions at the single-particle or local scale, so as to provide a more direct and reliable basis for material design, screening and mechanism research. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for characterizing the rate performance of single-particle electrode materials based on optical imaging. By acquiring the optical response information of single-particle electrode materials under controlled rate conditions and analyzing its characteristics as a function of rate, this method enables quantitative characterization of the reaction state and kinetic behavior of single particles at different time scales, overcoming the masking effect of averaging on the true performance information of particles in macroscopic testing.

[0006] Technical solution: The method for characterizing the rate performance of single-particle electrode materials based on optical imaging according to the present invention includes the following steps:

[0007] S1. Construct a test configuration suitable for electrochemical charging and discharging and allowing optical observation;

[0008] S2. Execute a constant current charge-discharge program under controlled rate conditions and simultaneously acquire optical signals;

[0009] S3. Based on the optical signal, define optical response characteristic parameters related to magnification, and evaluate the rate performance of single-particle electrode materials based on the optical response characteristic parameters.

[0010] In step S1, a well-dispersed single-particle electrode sheet is prepared. Specifically, the electrode material to be tested is dispersed in an appropriate manner, fixing it onto the surface of the current collector in a single-particle or low-aggregate state, thereby forming a single-particle dispersed electrode sheet. Subsequently, the electrode sheet is assembled with a lithium sheet, a separator, and an electrolyte to form an electrochemical testing unit. Holes are drilled in the center of the lithium sheet and the separator to ensure unobstructed light path. The battery adopts a standard half-cell structure and is assembled in an argon-filled glove box, thus enabling compatibility with electrochemical testing and optical observation. This allows incident light to illuminate the area of ​​the electrode to be tested and collect reflected or scattered signals, thereby achieving optical acquisition of the area of ​​the electrode to be tested without disassembling the battery.

[0011] In step S2, the assembled test unit is placed in a matching optical detection system for rate charge-discharge testing, and optical signals are acquired simultaneously. The optical detection system includes a microscopic imaging unit, a light source module, and a high-sensitivity detector, capable of resolving individual particles of the test within the micrometer to nanometer scale and recording their optical signals in real time. The electrochemical loading process and the optical acquisition process are coordinated by a synchronization control module to achieve synchronous acquisition of electrochemical and optical signals during charge-discharge.

[0012] In typical testing, the battery is subjected to constant current charge and discharge operations at different rates under constant temperature conditions, for example, sequentially from low rate to high rate (e.g., 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, etc.). In actual testing, the rate is usually selected according to the battery specifications and testing objectives, and can range from 0.1C to 30C. During charge and discharge, the individually dispersed electrode material undergoes electrochemical polarization under the influence of an electric field, and its optical properties change accordingly, resulting in differences in the response characteristics of the particle optical signal as a function of time or potential. This optical response reflects the differences in the reaction behavior of different particles under different rate conditions, and the testing system can simultaneously obtain dynamic optical response information from multiple particles.

[0013] In step S3, the optical image sequences acquired under different magnification conditions are analyzed and processed. First, the optical image sequences are preprocessed, including but not limited to background correction, noise suppression, and brightness normalization, to reduce the impact of imaging system drift and environmental fluctuations on the optical signal. Subsequently, based on the spatial location of the particles in the image, particle identification and region segmentation are performed on the optical images to determine the pixel region corresponding to each particle to be tested.

[0014] Based on this, the optical signals within the corresponding pixel region of each particle are statistically analyzed and extracted to obtain a time series of optical signals showing changes in the particle's optical signal over time or electrochemical state during the testing process. The optical signals may include reflection intensity, scattering intensity, brightness changes, or characteristic quantities calculated from spectral data. Through the above processing, single-particle-level time series extraction of optical signals is achieved.

[0015] The optical signal time series obtained from the same particle or different particles under different magnification conditions are compared and analyzed. Specifically, the optical signal time series obtained from the same particle under different magnification conditions are compared to analyze the response differences exhibited by the magnification; or, under the same magnification conditions, the optical signal time series of different particles are compared to evaluate the discreteness of the response behavior between particles. Based on this, optical response characteristic parameters that can reflect the characteristics of magnification changes are extracted, such as optical response amplitude, optical signal change rate, characteristic time required to reach steady state, and stability indicators of the response process.

[0016] By comparing the variation patterns of the optical response characteristic parameters under different rate conditions, the response capability of single-particle electrode materials under different rate conditions can be quantitatively characterized, thereby achieving the characterization and evaluation of the rate performance of single-particle electrode materials. This evaluation method does not rely on the average response of the macroscopic electrode or the entire battery, but is based on the optical behavior at the single-particle level, and can more directly reflect the intrinsic response characteristics of material particles at different time scales.

[0017] Furthermore, by repeating the aforementioned optical signal extraction, magnification comparison, and optical response characteristic parameter calculation process for multiple individual material particles within the same set of test data, and performing statistical analysis on the obtained optical response characteristic parameters, the distribution characteristics of the optical response characteristic parameters of a batch of material particles under different magnification conditions can be obtained. By summarizing and analyzing these distribution characteristics, the intrinsic magnification performance parameters of this batch of material particles can be obtained, which reflect the overall magnification performance level and its dispersion at the particle level of the material system.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0019] 1. By introducing optical imaging techniques to obtain the response information of particles during electrochemical loading, the response behavior of electrode materials under different rate conditions can be characterized at the single-particle scale. This helps to reduce the impact of averaging effects on rate performance evaluation in macroscopic testing, and maximizes the performance of the material itself. It can serve as an effective supplement to traditional methods, thereby further improving the efficiency of material optimization and development.

[0020] 2. Compared with traditional methods, this method does not require cumbersome sample copying, making the operation simpler and the testing efficiency higher;

[0021] 3. The method of the present invention has particle-level spatial resolution capability, which can separately acquire and analyze the magnification response of different particles in the same batch of materials, increasing the depth and breadth of information that can be obtained by the test. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the configuration of the testing device of the present invention.

[0023] Figure 2 This is the overall flowchart of this technical method.

[0024] Figure 3 The results show the change in charge / discharge capacity of Ni80 cathode material with the number of cycles under different rate conditions (0.5C→ 1C → 2C → 4C → 0.5C recovery).

[0025] Figure 4 The response curves show the optical intensity of Ni80 cathode material as a function of time under different magnification conditions.

[0026] Figure 5 This is a comparison chart of the rate performance results of single particles of Ni80 cathode material and the overall battery rate performance results.

[0027] Figure 6 The statistical distribution results of the normalized capacity of multi-particle Ni80 cathode material under different rate conditions are shown.

[0028] Figure 7 The results show the change in charge / discharge capacity of LFP cathode material with the number of cycles under different rate conditions (0.5C→ 1C → 2C → 4C → 4C → 0.5C recovery).

[0029] Figure 8 The response curves show the optical intensity of the LFP cathode material as a function of time under different magnification conditions.

[0030] Figure 9 This is a comparison chart of the rate performance results of single particles of LFP cathode material and the rate performance results of the overall battery.

[0031] Figure 10 The statistical distribution results of the normalized capacity of LFP cathode materials under different rate conditions are shown.

[0032] Figure 11 The results show the change in charge-discharge capacity of LCO cathode material with the number of cycles under different rate conditions (0.5C→ 1C → 2C → 4C → 4C → 0.5C recovery).

[0033] Figure 12 The response curves show the optical intensity of the LCO cathode material as a function of time under different magnification conditions.

[0034] Figure 13 This is a comparison chart of the rate performance results of single particles of LCO cathode material and the rate performance results of the overall battery.

[0035] Figure 14 The statistical distribution results of the normalized capacity of LCO cathode material under different rate conditions are shown. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] Example 1

[0038] This embodiment takes commercial Ni80 cathode material as the research object to illustrate the specific implementation process of the rate performance characterization method for single-particle electrode materials based on optical imaging described in this invention.

[0039] Commercially available Ni80 cathode material was selected as the sample to be tested. First, the Ni80 cathode material was dispersed using methods such as solution dispersion to ensure its uniform distribution as single particles or low-aggregation on the surface of the current collector, thereby preparing a well-dispersed Ni80 electrode sheet. The current collector can be a metal substrate with good conductivity or a transparent or semi-transparent conductive substrate.

[0040] Subsequently, the prepared Ni80 electrode sheet, lithium metal sheet, separator, and electrolyte are assembled together to form an electrochemical testing unit. A through-hole is provided at the center of the lithium sheet and separator to ensure unobstructed light path, allowing incident light to pass through and illuminate the area of ​​the electrode under test, and to collect reflected or scattered signals. The battery adopts a standard half-cell structure and is assembled in an argon-filled glove box to avoid the influence of air and moisture on the testing process, thus achieving compatibility between electrochemical testing and optical observation.

[0041] The assembled optical cell is placed in an optical detection system for testing. This system includes a microscopic imaging unit, a light source module, and a detector, capable of resolving Ni80 single particles with sizes in the micrometer or submicrometer range and recording their optical signals in real time. The electrochemical testing system and the optical detection system are linked through a synchronization control module to achieve simultaneous electrochemical loading and optical acquisition processes.

[0042] Under constant temperature conditions, the Ni80 electrode sheet was subjected to constant current charge-discharge operations at different rates sequentially, for example, in the order of 0.5C, 1C, 2C, and 4C. Under each rate condition, the corresponding charge-discharge cycle process was recorded, and optical image sequences of single-particle Ni80 material were acquired simultaneously.

[0043] In the data processing stage, the acquired optical image sequence is preprocessed, including background correction and noise suppression. Subsequently, based on the spatial location of particles in the image, particle identification is performed, and the optical signal within the corresponding pixel region of each particle is extracted to obtain a single-particle-level optical signal time series. Based on this single-particle optical signal time series, rate-related optical response characteristic parameters are extracted under different magnification conditions, such as optical response amplitude, optical signal change rate, and optical intensity level corresponding to the final state of charging and discharging. By comparing the optical response characteristic parameters obtained for the same particle under different magnification conditions, quantitative characterization of the rate performance of a single particle is achieved.

[0044] Single-particle dispersed Ni80 materials undergo electrochemical polarization under the action of an electric field. The insertion or extraction of lithium ions inside the particles causes changes in the optical properties of the particles, which are then manifested as the response characteristics of the particle optical signal changing over time. Figure 3 The results show the change of single-particle capacity obtained from optical cells with the number of cycles under different rate conditions. It can be seen that the capacity obtained at the single-particle level gradually decreases with increasing rate, and exhibits a certain degree of capacity recovery characteristics after rate recovery.

[0045] Furthermore, the optical response of a single particle under different magnification conditions was analyzed. Figure 4The response curves of the optical intensity of single-particle Ni80 material during charge and discharge processes at 0.5C, 1C, 2C, and 4C are shown. It can be observed that there are significant differences in the amplitude and evolution process of the particle optical signal under different charging and discharging conditions. Specifically, there are systematic differences in the optical intensity levels under different charging and discharging conditions at the charging and discharging cutoff points. By analyzing the change in optical intensity (Imax − Imin) throughout the entire charge and discharge process, it can be used as an optical parameter characterizing the state changes of a single particle during charge and discharge, reflecting the differences in the particle's response behavior under different charging and discharging conditions.

[0046] Furthermore, the above optical signal extraction and parameter calculation process was repeated for multiple particles, and the results were statistically analyzed. Figure 5 The comparison between the rate performance results of a single particle and the rate performance results of the overall battery is shown. It can be seen that the rate change trend of the single particle test results is consistent with that of the overall battery test results. Figure 6 The statistical distribution results of normalized capacity of multiple particles are shown under different magnification conditions. The central position and distribution pattern of particle capacity distribution are significantly different under different magnification conditions, reflecting the discreteness of particle response behavior under magnification conditions.

[0047] The above embodiments illustrate that the optical imaging-based single-particle electrode material rate performance characterization method of the present invention can acquire optical response information under different rate conditions at the single-particle scale, and achieve the characterization and evaluation of the rate performance of the electrode material by extracting and statistically analyzing the optical response characteristic parameters, thereby providing a new technical means for the research and analysis of material rate performance.

[0048] Example 2

[0049] This embodiment takes commercial LFP cathode material as the research object to further illustrate the applicability and versatility of the optical imaging-based single-particle electrode material rate performance characterization method of the present invention in different types of cathode materials.

[0050] Commercially available LFP cathode material was selected as the sample to be tested. First, the LFP cathode material was dispersed through methods such as solution dispersion and ultrasonic treatment to ensure its uniform distribution as single particles or low-aggregation on the surface of the current collector, thereby preparing a well-dispersed LFP electrode sheet. The current collector can be a metal substrate with good conductivity, or a transparent or semi-transparent conductive substrate, to meet the requirements of simultaneous electrochemical testing and optical imaging.

[0051] Subsequently, the prepared LFP electrode sheet is assembled with a lithium metal sheet, a separator, and an electrolyte to form an electrochemical testing unit. A through-hole is provided in the central region of the lithium sheet and separator to ensure unobstructed light path, allowing incident light to illuminate the area under test and collect reflected or scattered optical signals from the LFP single particles. The battery adopts a standard half-cell structure and is assembled in an inert atmosphere (such as argon) glove box to avoid interference from air and moisture during the testing process, thus achieving compatibility between electrochemical testing and optical observation.

[0052] The assembled optical cell is placed in an optical detection system for testing. This system includes a microscopic imaging unit, a light source module, and a detector, capable of resolving LFP single particles with dimensions at the micrometer scale and acquiring and recording their optical signals in real time. The electrochemical testing system and the optical detection system are linked through a synchronization control module to achieve synchronization between the electrochemical loading process and the optical acquisition process.

[0053] Under constant temperature conditions, the LFP electrode was subjected to constant current charge-discharge operations at different rates sequentially, for example, in the order of 0.5C → 1C → 2C → 4C → 8C → 0.5C recovery. Under each rate condition, the corresponding charge-discharge cycle process was recorded, and optical image sequences of the LFP single particle during the charge-discharge process were acquired simultaneously.

[0054] In the data processing stage, the acquired optical image sequences are preprocessed, including background correction, brightness normalization, and noise suppression. Subsequently, particle identification is performed based on the spatial location information of the particles in the images, and the optical signal within the corresponding pixel region of each particle is extracted to obtain a single-particle-scale optical signal time series. Based on this single-particle optical signal time series, rate-related optical response characteristic parameters are extracted under different magnification conditions, such as optical response amplitude, optical signal change rate, and optical intensity level corresponding to the final state of charging and discharging. By comparing the optical response characteristic parameters obtained for the same particle under different magnification conditions, quantitative characterization of the rate performance of LFP single particles is achieved.

[0055] When LFP single particles undergo lithium-ion insertion and deintercalation processes under the action of an external electric field, the changes in their internal phase transition behavior and lithium-ion distribution will cause changes in the optical properties of the particles, thus manifesting as the response characteristics of optical signals changing over time. Figure 7 The results show the change in single-particle charge-discharge capacity of LFP based on optical cells with the number of cycles under different rate conditions. It can be seen that as the rate increases, the capacity of the single-particle layer gradually decreases, and exhibits obvious capacity recovery characteristics after the rate recovers to 0.5C.

[0056] Furthermore, the optical response of LFP single particles under different magnification conditions was analyzed. Figure 8 The response curves of optical intensity as a function of time during the charge-discharge process of LFP single particles are shown under conditions of 0.5C, 1C, 2C, 4C, and 8C. It can be observed that there are significant differences in the amplitude and evolution process of the particle optical signal under different charging and discharging conditions, especially at the charging and discharging cutoff points, where the corresponding optical intensity levels under different charging and discharging conditions exhibit systematic differences. By analyzing the change in optical intensity (Imax − Imin) throughout the entire charge-discharge process, it can be used as an optical parameter characterizing the electrochemical state changes of LFP single particles, reflecting the differences in the particle's response behavior under different charging and discharging conditions.

[0057] Furthermore, the above optical signal extraction and parameter calculation process was repeated for multiple particles, and the results were statistically analyzed. Figure 9 The comparison between the rate performance results of LFP cathode material single particles and the overall battery rate performance results is shown. It can be seen that the rate performance variation trend at the single particle level is in good agreement with the overall battery test results. Figure 10 The statistical distribution results of normalized capacity of multiple particles are shown under different magnification conditions. The center position and distribution width of the particle capacity distribution are significantly different under different magnification conditions, reflecting the discrete characteristics of LFP particles in magnification response behavior.

[0058] As can be seen from the above embodiments, the optical imaging-based single-particle electrode material rate performance characterization method of the present invention is not only applicable to layered Ni-based cathode materials, but also to LFP cathode materials. It can obtain optical response information under different rate conditions at the single-particle scale, and through the extraction and statistical analysis of optical response characteristic parameters, it can effectively characterize and evaluate the rate performance of different types of electrode materials, and has good versatility and application value.

[0059] Example 3

[0060] This embodiment takes commercial LCO cathode material as the research object to further illustrate the applicability and versatility of the optical imaging-based single-particle electrode material rate performance characterization method described in this invention in different types of cathode materials.

[0061] Commercially available LCO cathode material was selected as the sample to be tested. First, the LCO cathode material was dispersed through methods such as solution dispersion and ultrasonic treatment to ensure its uniform distribution as single particles or low-aggregation on the surface of the current collector, thereby preparing a well-dispersed LCO electrode sheet. The current collector can be a metal substrate with good conductivity, or a transparent or semi-transparent conductive substrate, to meet the requirements of simultaneous electrochemical testing and optical imaging.

[0062] Subsequently, the prepared LCO electrode sheet, along with a lithium metal sheet, a separator, and an electrolyte, are assembled to form an electrochemical testing unit. Through-holes are provided in the central region of the lithium sheet and separator to ensure unobstructed light path, allowing incident light to illuminate the electrode area under test and collect reflected or scattered optical signals from LCO single particles. The battery employs a standard half-cell structure and is assembled in an inert atmosphere (such as argon) glove box to avoid interference from air and moisture during the testing process, thus achieving compatibility between electrochemical testing and optical observation.

[0063] The assembled optical cell is placed in an optical detection system for testing. This system includes a microscopic imaging unit, a light source module, and a detector, capable of resolving LCO single particles with dimensions at the micrometer scale and acquiring and recording their optical signals in real time. The electrochemical testing system and the optical detection system are linked through a synchronization control module to achieve synchronization between the electrochemical loading process and the optical acquisition process.

[0064] Under constant temperature conditions, the LCO electrode was subjected to constant current charge-discharge operations at different rates sequentially, for example, in the order of 0.3C → 5C → 4C → 2.5C → 1C → 0.3C recovery. Under each rate condition, the corresponding charge-discharge cycle process was recorded, and optical image sequences of LCO single particles during the charge-discharge process were acquired simultaneously.

[0065] In the data processing stage, the acquired optical image sequences are preprocessed, including background correction, brightness normalization, and noise suppression. Subsequently, particle identification is performed based on the spatial location information of the particles in the images, and the optical signal within the corresponding pixel region of each particle is extracted to obtain a single-particle-scale optical signal time series. Based on this single-particle optical signal time series, rate-related optical response characteristic parameters are extracted under different magnification conditions, such as optical response amplitude, optical signal change rate, and optical intensity level corresponding to the final state of charging and discharging. By comparing the optical response characteristic parameters obtained for the same particle under different magnification conditions, quantitative characterization of the rate performance of LCO single particles is achieved.

[0066] Under the influence of an applied electric field, LCO single particles undergo lithium-ion insertion and deintercalation processes. The changes in their internal phase transition behavior and lithium-ion distribution cause changes in the optical properties of the particles, which are manifested as the response characteristics of optical signals changing over time. Figure 11 The results show the variation of LCO single-particle charge-discharge capacity with cycle number under different rate conditions. It can be seen that as the rate increases, the capacity at the single-particle level gradually decreases, and exhibits a significant capacity recovery characteristic after the rate recovers to 0.3C.

[0067] Furthermore, the optical response of LCO single particles under different magnification conditions was analyzed. Figure 12 The response curves of the optical intensity of LCO single particles during charge and discharge processes are shown under the conditions of 0.3C → 5C → 4C → 2.5C → 1C → 0.3C. It can be observed that there are significant differences in the amplitude and evolution process of the particle optical signal under different rate conditions, especially at the charging and discharging cutoff points, where the corresponding optical intensity levels under different rate conditions exhibit systematic differences. By analyzing the change in optical intensity (Imax − Imin) throughout the entire charge and discharge process, it can be used as an optical parameter characterizing the electrochemical state changes of LCO single particles, reflecting the differences in the response behavior of particles under different rate conditions.

[0068] Furthermore, the above optical signal extraction and parameter calculation process was repeated for multiple particles, and the results were statistically analyzed. Figure 13 The comparison between the rate performance results of LCO cathode material single particles and the overall battery rate performance results shows that the rate performance variation trend at the single particle level is in good agreement with the overall battery test results. Figure 14 The statistical distribution results of normalized capacity of multiple particles are shown under different magnification conditions. The center position and distribution width of the particle capacity distribution are significantly different under different magnification conditions, reflecting the discrete characteristics of LCO particles in magnification response behavior.

[0069] As can be seen from the above embodiments, the optical imaging-based single-particle electrode material rate performance characterization method of the present invention is also applicable to LCO cathode materials. It can obtain optical response information under different rate conditions at the single-particle scale, and through the extraction and statistical analysis of optical response characteristic parameters, it can effectively characterize and evaluate the rate performance of different types of electrode materials, and has good versatility and application value.

Claims

1. A method for characterizing the rate performance of single-particle electrode materials based on optical imaging, characterized in that, Includes the following steps: S1. Construct a test configuration suitable for electrochemical charging and discharging and allowing optical observation; S2. Execute a constant current charge-discharge program under controlled rate conditions and simultaneously acquire optical signals; S3. Based on the optical signal, define optical response characteristic parameters related to magnification, and evaluate the rate performance of single-particle electrode materials based on the optical response characteristic parameters.

2. The method according to claim 1, characterized in that, Step S1 specifically includes: S11. Disperse the electrode material to be tested so that it is fixed on the surface of the current collector in a single particle or low-aggregate state to form a single particle dispersed electrode sheet. S12. Assemble the electrode sheet, lithium sheet, separator, and electrolyte into an electrochemical testing unit; drill holes in the center of the lithium sheet and separator to ensure unobstructed optical path; S13. The electrochemical test unit is packaged into a standard half-cell structure in an inert atmosphere.

3. The method according to claim 1, characterized in that, Step S2 specifically includes: S21. Place the assembled test configuration into the optical detection system for rate charge-discharge testing and simultaneously acquire optical signals; the electrochemical loading process and the optical acquisition process are coordinated by a synchronous control module to achieve synchronous acquisition of electrochemical signals and optical signals during the charge-discharge process; S22. Under constant temperature conditions, apply constant current charge and discharge operations at different rates to the test configuration.

4. The method according to claim 3, characterized in that, In step S22, the different magnifications include testing in sequence from low magnification to high magnification.

5. The method according to claim 1, characterized in that, Step S3 includes processing the optical signal as follows: S31. Preprocess the acquired optical image sequence, including background correction, noise suppression and brightness normalization. S32. Based on the spatial position of the particles in the image, perform particle identification and region division on the preprocessed optical image to determine the pixel region corresponding to each particle to be tested. S33. Statistically analyze and extract the optical signals within the corresponding pixel area of ​​each particle to obtain the time series of optical signals of each particle as it changes with time or electrochemical state during the test.

6. The method according to claim 5, characterized in that, The optical signal in step S33 includes reflection intensity, scattering intensity, brightness change, or characteristic quantities calculated from spectral data.

7. The method according to claim 1, characterized in that, In step S3, optical response characteristic parameters that can reflect the magnification change characteristics are extracted. Under different magnification conditions, the time series of optical signals obtained from the same particle or different particles are compared and analyzed. By comparing the variation law of the optical response characteristic parameters under different magnification conditions, the response capability of single-particle electrode material under different magnification conditions is quantitatively characterized, thereby realizing the characterization and evaluation of the magnification performance of single-particle electrode material.

8. The method according to claim 7, characterized in that, The optical response characteristic parameters include optical response amplitude, optical signal change rate, characteristic time required to reach steady state, and stability index of the response process.

9. The method according to claim 1, characterized in that, In step S3, the optical signal time series of the same particle obtained under different magnification conditions are compared to analyze the response differences exhibited by the particle as the magnification changes; or, under the same magnification conditions, the optical signal time series of different particles are compared to evaluate the discreteness of the response behavior between particles.

10. The method according to claim 1, characterized in that, The method further includes: repeatedly extracting optical signals, comparing magnification, and calculating optical response characteristic parameters for multiple individual material particles contained in the same set of test data; statistically analyzing the obtained optical response characteristic parameters to obtain the distribution characteristics of optical response characteristic parameters of a batch of material particles under different magnification conditions; and summarizing and analyzing the distribution characteristics to obtain the intrinsic magnification performance parameters of the batch of material particles, which are used to reflect the overall magnification performance level and its dispersion of the material system at the particle level.

Images