A high-throughput screening method for lithium ion battery electrode materials based on single particle electrochemical technology

Abstract

This invention discloses a high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology. The method first uses automated spotting technology to deposit sample solutions of various electrode materials in an array onto the same conductive substrate, forming a microarray containing multiple independent deposition points. Subsequently, this array is assembled into an electrochemical testing unit. During charge and discharge, an optical imaging system is used to monitor the dynamic optical response of each deposition point in situ and synchronously. Finally, the optical signals of each point are extracted and analyzed, and electrochemical parameters for evaluating material performance are obtained through fitting. This invention can acquire intrinsic electrochemical response data of dozens to hundreds of material particles in a single experiment, offering high throughput, simple operation, and avoiding interference from conductive agents and binders in traditional electrode preparation. It can accurately reflect material characteristics and significantly improve the efficiency of electrode material research and screening.

Description

Technical Field

[0001] This invention relates to lithium-ion battery material performance characterization technology, specifically to a high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology. Background Technology

[0002] Electrode materials are key limiting factors affecting the energy density, cost, and cycle stability of lithium-ion batteries. Taking power batteries as an example, insufficient range, slow charging, and safety hazards are all closely related to the performance of electrode materials. Currently, the system specific energy of mainstream battery cells is typically below 260 Wh / kg, and electrode costs account for 30%–40% of the total battery cost. Furthermore, slow charging kinetics easily lead to structural degradation and performance decline. Therefore, developing high-performance electrode materials is a core task for improving the overall performance of lithium-ion batteries. Currently, the industry commonly uses two main screening methods: trial-and-error screening methods based on macroscopic performance testing and emerging computational simulation screening methods.

[0003] The main drawback of the trial-and-error method lies in the fact that the test unit is a complete battery structure, rather than a single material itself. Each test requires a complete electrode preparation and battery assembly process to obtain performance data for a particular material. The defects of this method are: First, the experimental process is complex and time-consuming. Each material needs to independently complete processes such as drying, mixing, coating, pressing, assembly, and formation, resulting in low throughput and low R&D efficiency. Second, the intrinsic properties of materials are easily affected by mixing. The addition of conductive agents and binders introduces interface effects and ratio differences, causing the test results to deviate from the true performance of the particles. Third, the test conditions vary greatly. Electrodes of each material need to be prepared and assembled separately. Differences in thickness, density, interfacial contact, and liquid injection volume make it difficult to compare different samples. Fourth, the test object is not specific. The measured results are simultaneously affected by multiple factors such as active materials, conductive agents, binders, electrolyte wettability, electrode thickness, and compaction density, making it difficult to accurately reflect the intrinsic electrochemical behavior of material particles. The shortcomings of computational simulation methods stem from their technical characteristic of replacing actual electrochemical tests with theoretical models: First, the accuracy of simulations is limited by the assumptions and simplifications of the computational model. Theoretical models usually treat materials as ideal crystal structures, ignoring actual factors such as particle size effects, surface defects, and chemical reactions at the electrode / electrolyte interface, making it difficult to fully reflect the real electrochemical environment. Second, the prediction results of machine learning models depend on the completeness and quality of the training data. Their performance is limited by the number of database samples and the coverage of the feature space. When the input data contains noise or unclear physical meaning, the predicted values ​​are prone to deviation and lack verifiability. Third, this type of method lacks an experimental feedback loop and cannot reflect the kinetic behavior and stability of materials in actual electrochemical systems. The predicted results often differ from experimental performance.

[0004] In summary, the existing technology lacks a screening method that combines high throughput, experimental operability, and single-particle resolution, which can obtain reliable experimental data in a real electrochemical environment and achieve large-scale, automated sample testing and statistical analysis to meet the needs of rapid development of novel lithium-ion battery electrode materials. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology, which solves the problem that high-throughput material screening and accurate characterization of intrinsic electrochemical performance cannot be achieved simultaneously in the prior art.

[0006] Technical solution: The high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology described in this invention includes the following steps:

[0007] S1. Preparation of spotted electrode: Prepare a conductive substrate, and deposit various lithium-ion battery electrode material sample solutions in an array on the same conductive substrate using an automatic spotting technique to form a microarray containing multiple independent deposition points.

[0008] S2. Assembly and Optical Testing: The electrode sheet carrying the microarray is assembled with the counter electrode and electrolyte into an electrochemical testing unit; during the electrochemical charging and discharging process of the testing unit, the microarray is monitored in situ and synchronously using an optical imaging system to record the dynamic optical response signal of each deposition point.

[0009] S3. Data Processing: Extract the optical response data corresponding to each deposition point or individual particle from the dynamic optical response signal, and obtain the electrochemical response parameters for evaluating the performance of the electrode material through fitting and statistical analysis.

[0010] The method is universal and applicable to lithium-ion battery materials available on the market.

[0011] In step S1, the microarray of multiple independent deposition points is a multi-point sampling according to the requirements. The arrangement can be an m×n array (m and n are positive integers ≥2), such as 10×10, 8×9, 7×6, 5×5, etc.

[0012] Preferably, in step S1, preparing the conductive substrate specifically includes: mixing a conductive agent and a binder, coating the mixture onto the surface of a metal current collector, and then drying it to form the substrate. This can be done using a normal electrode preparation process, such as a conductive agent to binder ratio of 1:4 to 6, more preferably 1:5.

[0013] Preferably, in step S1, the automatic spotting technology is performed using metal microneedles with a tip diameter of 40-60 μm; the diameter of each deposition point formed after spotting deposition is 80-120 μm.

[0014] Preferably, each deposition point contains multiple independent electrode material particles, and the particles are spatially dispersed within the deposition point. The multiple independent electrode material particles refer to the number of individual particles in the deposition point, such as 60-500 (micron-sized materials such as graphite); 100-1000 (nano-sized materials such as Ni80).

[0015] Preferably, in step S1, the lithium-ion battery electrode material sample solution is applied to the conductive substrate at preset coordinate positions using a program-controlled automatic spotting technique, so that the deposition points corresponding to different materials have an addressable spatial distribution in the microarray.

[0016] Preferably, in step S2, the electrochemical testing unit is a half-cell structure with lithium metal as the counter electrode.

[0017] Preferably, in step S2, the optical imaging system includes a microscopic imaging unit, a light source module, and a high-sensitivity detector, whose spatial resolution is capable of distinguishing particles at the micrometer to submicrometer scale.

[0018] Preferably, in step S2, the electrochemical charge-discharge is a constant current charge-discharge test.

[0019] Preferably, in step S2, the electrode material particles in all deposition points of the microarray are in the same electrochemical environment in the electrochemical testing unit, and through a synchronous optical monitoring process, the dynamic optical response signals of different material particles under the same charge and discharge conditions are obtained simultaneously, which are used to directly compare their intrinsic electrochemical characteristics.

[0020] Preferably, in step S3, the fitting is performed by fitting the optical intensity-voltage curve using the Lorentz function;

[0021] The Lorentz function is:

[0022]

[0023] Where x represents the applied voltage value, which is the scanning voltage applied to the array electrodes or the instantaneous voltage during the charging and discharging process; y represents the single-particle optical response intensity measured corresponding to the applied voltage x, which is the light intensity signal recorded by the particle in the optical imaging system, obtained after normalization; y0 represents the background optical signal or baseline optical intensity, used to eliminate the influence of system background noise; x cThe peak position parameter obtained from the fitting corresponds to the characteristic voltage when the particle exhibits a significant electrochemical response. This characteristic voltage is used to characterize the phase transition voltage or characteristic reaction potential of the particulate material; w is the peak width parameter, which reflects the width of the time or voltage distribution of the electrochemical response process and characterizes the synchronicity or dispersion of the electrochemical response process; A is the peak area parameter, which characterizes the overall intensity of the particle's optical response.

[0024] As a preferred approach, the process is generally divided into three parts: spot electrode preparation, assembly and testing, and data processing.

[0025] First, an electrode substrate for spotting is prepared. A conductive agent and binder are mixed uniformly at a preset mass ratio (e.g., conductive carbon black: binder = 8:2), and then coated onto the cleaned surface of an aluminum foil current collector to form a uniform conductive layer, ensuring good electronic conductivity. The resulting coating is then rolled to improve compaction density and flatness, and dried in a vacuum oven at 80 ℃. The dried electrode is cut into standard circles and fixed to the center of a glass slide using a clamp, serving as the substrate for subsequent spotting. This step ensures the flatness of the spotting area and a stable bond between the electrode substrate and the glass carrier, providing mechanical support and a positioning reference for subsequent automated multi-point spotting.

[0026] The lithium-ion battery electrode material powder to be tested is dispersed in N-methylpyrrolidone (NMP) or other polar organic solvents and ultrasonically treated to obtain a sample solution with uniform particle distribution. The diluted sample solution is then dripped into the well plate. A metal microneedle (tip diameter approximately 50 μm) is used as the sampling and transfer tool to fix the well plate, the sampling needle, and the sampling substrate to the sampling instrument. The sampling program (liquid collection interval, drop speed, contact time, ambient humidity) is set, and the needle tip raising, lowering, and immersion process are precisely controlled by the fully automated sampling platform of the biochip sampling instrument. Capillary force is used to adhere a small amount of sample liquid to the tip of the needle, ensuring consistent sample volume each time.

[0027] Subsequently, using a high-precision three-dimensional servo displacement platform (with micron-level positioning accuracy), the sample-carrying needle tip is moved to a preset coordinate position and gently touches the electrode substrate surface, achieving automatic detachment and precise deposition of microdroplets. Computer program control enables fully automated, multi-point repeatable spotting, allowing for the preparation of arrays of up to 60 sample substrates in a single operation. A visual user interface and programmed coordinate editing allow for flexible adjustment of spotting parameters based on particle size or electrode requirements. Each microdroplet forms a deposition point approximately 100 μm in diameter after the solvent naturally evaporates. Each deposition point contains approximately 50 independent particles spatially dispersed, which can be considered as a single-particle-level electrochemical testing unit.

[0028] In the assembly and testing phase, the prepared array electrode sheets are assembled together with the lithium sheet and electrolyte to form an electrochemical testing unit. Holes are drilled in the center of the lithium sheet and separator to ensure unobstructed optical path. The battery adopts a standard half-cell structure and is assembled in an argon-filled glove box, compatible with both electrochemical testing and optical observation.

[0029] The test unit, equipped with the array electrode sheet, is placed in a matching optical detection system for testing, and optical images of the test particles are recorded in real time. The optical detection system includes a microscopic imaging unit, a light source module, and a high-sensitivity detector. Its core function is to resolve test particles ranging in size from hundreds of nanometers to tens of micrometers and to record images in real time. Electrochemical loading and optical acquisition are achieved by a synchronous control module, which can record the light intensity response of the particles under voltage changes in real time.

[0030] In a typical experiment, the battery undergoes periodic charge-discharge tests, causing the arrayed particles to undergo electrochemical polarization under the influence of an electric field. This alters their local refractive index, absorption coefficient, and luminescence properties, resulting in dynamic changes in the particle's optical response. From an optical perspective, these changes manifest as differences in optical intensity and time response characteristics among different particles in the array. These differences reflect the intrinsic electrochemical properties of different particles during electrochemical polarization, such as ion migration rate, interfacial reactivity, and charge transport efficiency. This system can simultaneously obtain the dynamic optical response of the entire particle array.

[0031] In the data processing section, code is used to extract the light intensity signal of each particle at the single-particle level time series. The Lorentz function is then used for fitting to obtain the voltage response parameters corresponding to each particle, thus revealing the different phase transition voltages for each material.

[0032] By fitting the optical response intensity-voltage curve of a single particle with the Lorentz function, the characteristic voltage parameters corresponding to different particles or different materials can be quantitatively obtained, thereby enabling the analysis and comparison of the intrinsic electrochemical behavior of materials.

[0033] Statistical analysis reveals the correlations and differences in the electrochemical behaviors of different particles in the array, enabling high-throughput characterization of battery material performance. This method can resolve voltage response differences between particles at the microscale, providing an intuitive and quantifiable analytical approach for understanding the phase transition dynamics of material systems under an electric field. Furthermore, it directly provides intuitive comparisons of material performance, enabling rapid performance screening and significantly improving the efficiency of electrode material development and quality assessment.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0035] 1. This method fundamentally enables the simultaneous acquisition of statistical electrochemical response data for dozens to hundreds of electrode material particles in a single experiment. By utilizing spotting technology to construct array structures containing multiple materials on the same current collector in an addressable manner, and obtaining the electrochemical performance parameters of all spotted materials in a single electrochemical experiment, it makes simultaneous detection of high-throughput electrode material particles possible. This maximizes the throughput of material detection, significantly improves experimental efficiency and data volume, and solves the problems of low throughput and poor efficiency in traditional methods.

[0036] 2. Compared to traditional methods, this method eliminates the need for cumbersome sample preparation, bypassing traditional sample pretreatment procedures and directly detecting hundreds of different sample particles. The method is simpler to operate, avoiding the complex process of repeatedly preparing complete electrodes for each material, thus significantly improving testing efficiency.

[0037] 3. This method avoids the influence of conductive agents and binders on measurement results in traditional electrode preparation, and can truly reflect the intrinsic characteristics of particles, increasing the depth and breadth of information that can be obtained from the test. At the same time, the introduction of optical imaging as the detection end provides spatial resolution and greatly improves detection sensitivity, making it possible to simultaneously record the dynamic response of particles using optical microscopy during electrochemical charging and discharging.

[0038] 4. The core of this invention lies in providing a multi-particle electrochemical behavior detection method based on a combination of spot array and optical imaging. This approach forms a particle array through precise spotting and simultaneously performs optical monitoring and electrochemical testing, achieving parallel detection of particles of different materials. This is significantly different from traditional single detection methods and also has the advantages of high sensitivity, non-contact operation, and ease of use. Attached Figure Description

[0039] Figure 1 This diagram illustrates the preparation of the electrode substrate for spotting and the substrate loading process, as well as the process of dispersing the electrode material and sampling and transferring it using metal microneedles.

[0040] Figure 2 This is an overall flowchart of the high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology described in this invention.

[0041] Figure 3 This is an optical microscopic image of a high-throughput array deposition point prepared using the method of this invention.

[0042] Figure 4The images show optical microscopic images of deposition points of various negative electrode material arrays prepared using the method of this invention. From left to right, they are: CMB-Z high-pressure compacted mesophase carbon microspheres, GHMG dynamic modified artificial graphite, MS-QCG-X soft carbon coated fast-charging rate-enhancing artificial graphite, natural graphite, flake graphite, and artificial graphite.

[0043] Figure 5 The images show optical microscopic images of various cathode material array deposition points prepared using the method of this invention. From left to right, they are: Ni80 (CATL), LFP (CATL), P198-DFs LFP, P198-S13 LFP, LMFP, S198-S20 LFP, NCM525, and NCM (rate)-S.

[0044] Figure 6 This is a schematic diagram of the Lorentz fitting phase transition potential calculation of the present invention.

[0045] Figure 7 The image shows an optical imaging pattern (from top to bottom) of a spot array of three graphite samples (novel artificial dynamic graphite, natural graphite, and soft carbon coated graphite) of the present invention.

[0046] Figure 8 This is a typical response of the light intensity of the three graphite sample particles in this invention as a function of voltage.

[0047] Figure 9 The diagram shows a comparison of the phase transition voltages of three types of graphite in this invention (from top to bottom: novel artificial dynamic graphite, natural graphite, and soft carbon coated graphite).

[0048] Figure 10 This is a schematic diagram illustrating the normalized optical response curve and shape folding analysis of a single-particle array of lithium iron phosphate (LFP) cathode material in Example 2 of the present invention; wherein, Figure 10 (a) in the image is an optical microscopic image of an LFP single-particle array; Figure 10 (b) in the figure shows the curves of the original optical intensity of multiple single particles changing with time during the electrochemical charge-discharge process; Figure 10 (c) in the figure represents the 25 single-particle optical response curves after normalization. Figure 10 (d) in the figure is the distribution of the normalized standard deviation of optical intensity based on time point statistics.

[0049] Figure 11 This is a schematic diagram illustrating the normalized optical response and voltage-current cycling stability of a lithium iron phosphate (LFP) single-particle array during multiple electrochemical cycles in Example 2 of the present invention; wherein, Figure 11 (a) in the image shows a typical optical imaging diagram of a single LFP particle during the charging process at a higher resolution. Figure 11(b) in the figure shows the normalized optical intensity of multiple single particles as a function of time during six consecutive constant voltage charge-discharge cycles. Detailed Implementation

[0050] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0051] Example 1: Verification of the universality of the arrayed single-particle testing system in spotting arrays of different electrode materials.

[0052] To verify the universality and applicability of the arrayed single-particle testing system described in this invention in the preparation of spot arrays of different types of electrode materials, this embodiment selects a variety of typical lithium-ion battery positive and negative electrode materials as test objects, and performs arrayed spot preparation according to a unified spot electrode preparation process. The morphology of the deposition points, array distribution and particle dispersion state are characterized by optical microscopy to verify the compatibility and feasibility of the system for different material systems.

[0053] like Figure 1 The diagram schematically illustrates the electrode substrate and its mounting structure for spotting according to the present invention. In this embodiment, the electrode substrate for spotting is first prepared: a conductive agent and a binder are mixed uniformly according to a preset mass ratio and then coated onto the surface of an aluminum foil current collector to form a conductive layer. The resulting coating is then rolled to improve compaction density and surface flatness, and subsequently dried. The electrode sheet is then cut to a standard size and fixed in the center of a glass slide as the spotting substrate. Through this method, a spotting platform with a smooth surface, continuous conductivity, and mechanical stability can be obtained, thereby providing a positioning reference and consistent electrical contact conditions for subsequent multi-point array deposition, while ensuring that the substrate structure is compatible with automated spotting processes and subsequent electrochemical and optical testing requirements. Furthermore, Figure 1 The dispersion, sampling, and transfer processes of the electrode material are also illustrated. The electrode material to be tested is dispersed in a solvent and ultrasonically treated to obtain a uniformly dispersed sample dispersion system. The sample solution is then added to a well plate. A metal microneedle is used as the sampling and transfer tool. The well plate, the microneedle, and the sampling substrate are fixed to the microneedle applicator. By setting the microneedle applicator parameters (including sampling interval, needle tip descent speed, contact time, and ambient humidity), an automated platform controls the needle tip immersion, lifting, and contact processes. This allows a small amount of sample solution to stably adhere to the needle tip under capillary force and deposit at a preset location. Through unified control of these parameters, arrayed, multi-location repeatable microneedle applicator operations can be achieved, ensuring the repeatability of deposition point size, location, and particle loading.

[0054] like Figure 2The diagram shown is an overall flowchart of the high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology described in this invention. The sample preparation, assembly testing, and data processing in this embodiment all follow this process. In particular, the sample preparation stage utilizes programmed coordinate editing and automatic sample preparation control to achieve arrayed deposition of multiple samples at multiple locations, providing a unified sample basis for subsequent single-particle-level testing and analysis.

[0055] The optical microscopic imaging results of the arrayed deposition points prepared by the above method are as follows: Figure 3 As shown in the figure, 8*9 array spotting was performed using graphite as an example of anode material. As can be seen from the figure, the prepared deposition points are spatially distributed in a regular array. Each deposition point is independent and has clear boundaries, and the overall array is well-organized, indicating that the method of this invention can achieve stable and repeatable high-throughput array preparation. Under typical conditions, each deposition point forms a micro-area deposition structure with controllable scale after solvent evaporation. The deposition point contains multiple spatially dispersed particle units, which can meet the subsequent electrochemical and optical testing requirements of single particles or a small number of particles, thus demonstrating the feasibility of this system for the construction of arrayed single-particle samples.

[0056] Furthermore, to verify the applicability of the method of the present invention in different anode material systems, various representative anode materials were selected for spot preparation, and the optical microscopic imaging results are as follows: Figure 4 As shown, from left to right: CMB-Z high-compact mesophase carbon microspheres, GHMG dynamic modified artificial graphite, MS-QCG-X soft carbon-coated fast-charging rate-enhancing artificial graphite, natural graphite, flake graphite, and artificial graphite. It can be seen that anode materials with different morphologies, particle sizes, and surface properties can all form clearly identifiable arrayed deposition points under the same spotting process and parameter system. Furthermore, the particles within the deposition points are discretely distributed, indicating that the spotting and substrate configuration of this invention is compatible with multiple types of carbon-based anode materials and possesses good preparation versatility.

[0057] Similarly, to verify the universality of the method of the present invention in cathode material systems, various typical cathode materials were selected for spot preparation, and the optical microscopic imaging results are as follows. Figure 5 As shown in the figure, from left to right, the cathode materials are: Ni80 (CATL), LFP (CATL), P198-DFs LFP, P198-S13 LFP, LMFP, S198-S20 LFP, NCM525, and NCM (rate)-S. As can be seen from the figure, the cathode materials with different chemical systems, particle morphologies, and rate orientations can all achieve array deposition under a unified spotting preparation process. The deposition points are clearly distributed and optically identifiable, indicating that the method of this invention has good applicability to different cathode material systems.

[0058] Furthermore, such as Figure 6 As shown, the light intensity signal of each particle is extracted using code at the single-particle level time series. The Lorentz function is then used for fitting to obtain the voltage response parameters corresponding to each particle, thus revealing the different phase transition voltages for each material.

[0059] In summary, by comparing and analyzing the arrayed spotting preparation results and their microscopic imaging results of various negative and positive electrode materials, it can be verified that the arrayed single-particle testing system described in this invention can stably achieve the construction of arrayed deposition points in different types of electrode material systems, demonstrating good applicability and universality. This system can provide a unified and repeatable sample configuration basis for subsequent single-particle electrochemical testing and optical observation, and lay the foundation for high-throughput screening and comparative analysis of multi-material systems.

[0060] Example 2

[0061] To verify the ability of the arrayed single-particle testing system of this invention to distinguish the electrochemical responses of different particles, three typical graphite anode materials were selected for comparative experiments: natural graphite (NG), dynamic artificial graphite (GHMG), and soft carbon coated graphite (SCG).

[0062] In the sample preparation process, a conductive substrate was first prepared: conductive carbon black and polyvinylidene fluoride (PVDF) binder were mixed in N-methylpyrrolidone (NMP) at a mass ratio of 2:8 and stirred evenly to form a slurry. This slurry was then coated onto the surface of a clean copper foil current collector and dried under vacuum at 80°C for 12 hours before being cut for use. Three typical graphite-based anode materials were dispersed separately in NMP solution and, after being sonicated for 10 minutes to achieve thorough dispersion, were loaded into a well plate. Using a metal microneedle with a tip diameter of 50 μm, the sample solution was sequentially spotted onto the conductive substrate using a biochip spotting instrument. After spotting, the solvent evaporated, forming circular deposition points with a diameter of approximately 100 μm, each containing approximately 200 independently dispersed electrode material particles. Subsequently, these were assembled to form an observable cell suitable for an optical system (as described above) and placed in an electrochemical-optical synchronous testing system for measurement.

[0063] During the test, constant current charging and discharging were performed at different rates, and the high-resolution optical imaging system of this invention was used to acquire optical image sequences of each particle in the array in real time. The resulting representative optical images are shown below. Figure 7 As shown.

[0064] Furthermore, such as Figure 8 As shown, after code processing and normalization calculation, the curve of particle light intensity changing with time is obtained. Further, through Lorentz fitting, the spatial distribution map of the corresponding phase transition voltage value of the particle is obtained.

[0065] Experimental results are as follows Figure 9As shown, particles in different regions of the array exhibit significantly different optical response characteristics during electrochemical polarization. GHMG dynamic artificial graphite particles show relatively small overall light intensity changes and a narrow polarization potential range during charging and discharging. Natural graphite particles, on the other hand, show abrupt light intensity signals in the approximately 0.04-0.06 V range, corresponding to their typical phase transition potential. The phase transition peak of soft carbon-coated graphite particles is slightly lower than that of natural graphite, indicating that the coating layer has a buffering and delaying effect on the lithium insertion / extraction process.

[0066] Analysis of the fitting between the optical signals and synchronous electrochemical curves of each particle revealed that natural graphite had the highest phase transition potential and the largest ion intercalation barrier; the phase transition potential difference between natural graphite and soft carbon-coated graphite was approximately 30-50 mV; and dynamic synthetic graphite exhibited a faster response rate and the smallest polarization. This indicates that the results, obtained under the same electrochemical environment, reveal that inherent structural and property differences lead to varying electro-optic response rates and amplitudes.

[0067] Furthermore, the array exhibits excellent signal stability under low current density conditions, and the morphology of the sampled particles maintains good consistency after multiple cycles, indicating that the sample preparation method proposed in this invention can effectively eliminate interference caused by differences in batch slurry stirring, environmental conditions, etc. in traditional single-electrode testing. The experimental results obtained by this method are true, reliable, and highly repeatable.

[0068] To verify the influence of tip diameter and deposition point size on the test results, microneedles with tip diameters of 40 μm, 50 μm, and 60 μm were used for spotting, resulting in deposition point diameters of 80 μm, 100 μm, and 120 μm, respectively. Experimental results show that within this parameter range, particles are uniformly dispersed within the deposition point, the optical signal is clearly distinguishable, and there is no significant crosstalk. Therefore, a tip diameter of 40–60 μm and a deposition point diameter of 80–120 μm are the preferred ranges, ensuring high throughput while maintaining single-particle resolution.

[0069] In summary, as can be seen from this embodiment, the arrayed single-particle electrochemical testing system constructed by the present invention can simultaneously obtain independent response signals of multiple particles on the same substrate, realize dynamic comparison of different particles under the same electrochemical conditions, reveal the phase transition potential difference and charging characteristics between materials, and provide an effective means for high-throughput structure-performance correlation analysis of electrode materials.

[0070] Example 3

[0071] This embodiment takes lithium iron phosphate (LiFePO4, abbreviated as LFP) cathode material as the research object, and further demonstrates the applicability of the present invention to cathode materials, as well as the consistency and cycle stability of the test.

[0072] Dispersed LFP single particles were spotted onto the electrode using a spotting method to construct a regular single-particle array structure. Specifically, a 5×5 array was formed on the substrate, containing 25 spatially defined and separated sample pad test units, such as... Figure 10 As shown in (a) above, a fixed spacing is maintained between adjacent individual particles to avoid electrochemical coupling and optical signal crosstalk between particles. Similarly, the single-particle array is assembled with an electrolyte and a counter electrode to form a visualized battery structure suitable for in-situ optical observation, and then placed under an optical microscope for in-situ imaging. Under external electrochemical excitation, optical image sequences of each individual particle in the array are acquired synchronously to obtain data on the change of optical intensity over time at the single-particle scale. All individual particles in the array are under the same electrolyte environment, potential program, and optical imaging conditions, providing a unified testing basis for subsequent consistency and cycleability analysis.

[0073] Time evolution characteristics of single-particle optical response (I–t curve): Under the action of an applied electrochemical process, single or multiple LFP single particles are selected from the array, and their optical intensity changes over time, respectively. For example... Figure 10 As shown in (b), during electrochemical charge-discharge, the optical intensity of a single particle exhibits a repeatable periodic response behavior to changes in potential. The initial optical intensities of different single particles differ in their initial values, variation ranges, and absolute values. These differences mainly stem from subtle variations in particle size, local optical background, and imaging conditions. Therefore, it is difficult to directly compare the kinetic consistency between different single particles based solely on the variation range of their initial optical intensity.

[0074] Normalization and shape folding analysis of single-particle optical response: To eliminate the influence of differences in initial and final light intensities among different single particles on the analysis results, the optical intensity-time curve of each single particle was normalized. (Specifically, the initial light intensity I0 and the light intensity I of the stable plateau after the reaction were determined for each single-particle optical response curve.) ss And normalize according to the following formula:

[0075]

[0076] After normalization, the optical responses of each individual particle are uniformly mapped to 1 at the initial moment and approach 0 after the reaction is completed, thus compressing the optical responses of different individual particles into the same dimensionless coordinate system.

[0077] like Figure 10As shown in (c), the 25 normalized single-particle optical response curves highly overlap throughout the reaction process, exhibiting a clear "shape folding" characteristic. Simultaneously, the standard deviation envelope of their average normalized curves is relatively narrow, indicating a high degree of consistency in the dynamic evolution morphology of different single particles.

[0078] like Figure 10 As shown in (d), the optical response discreteness analysis based on time-point statistics (Method 2) involves statistically analyzing the optical intensity distribution of individual particles at each time point in the array, based on normalization, to further quantitatively evaluate the consistency of the optical response of a single particle. Specifically, at each time t, the normalized optical intensity I of the 25 individual particles in the array is analyzed. norm The standard deviation was calculated. The results show that the standard deviation of the normalized optical intensity remained at a low level throughout the entire electrochemical response and did not increase significantly over time, indicating that there was no obvious bifurcation or mismatch behavior among the different single particles during the kinetic evolution. These results further verify that, under the same electrochemical conditions, the LFP single particles in the spot array exhibit a highly consistent optical-electrochemical kinetic response.

[0079] Cyclic stability and repeatability verification of single-particle optical response: To verify the stability and repeatability of the method of this invention under multiple electrochemical cycles, a periodic constant voltage charge-discharge program was applied to a single-particle array at a higher resolution. The specific test conditions were: constant voltage charging at 3.8 V for 30 min, followed by resting for 10 min, and then constant voltage discharging at 3.0 V for 30 min. The above process constituted a complete cycle, and was repeated continuously for 6 cycles.

[0080] Figure 11 Image (a) shows a typical image of particle charging at a higher magnification. For example... Figure 11 As shown in (b), during multiple cycles, the normalized optical intensity I / I0 curves of a single particle over time maintained good overlap between cycles, and no significant drift was observed in its response amplitude, trend, or characteristic time. Simultaneously, the corresponding voltage-current curves remained stable in each cycle, and no abnormal polarization or irreversible behavior was observed. These results demonstrate that the spot-sampled single-particle array and its optical-electrochemical synchronous testing method constructed in this invention can operate stably under multiple electrochemical cycles, exhibiting good cycle consistency and signal repeatability.

[0081] As can be seen from Example 3, although different LFP single particles in the spot array have certain differences in the original optical signal amplitude, after normalization, their optical response evolution over time is highly consistent and remains stable and repeatable during multiple constant-pressure cycles. Therefore, the single-particle optical response consistency and cycle stability characterization method based on spot array proposed in this invention can reliably extract characteristic information reflecting the intrinsic dynamic behavior of materials at the single-particle scale, significantly improving the comparability, stability, and statistical reliability of single-particle electrochemical test results, and is suitable for high-throughput screening and performance evaluation of electrode materials.

Claims

1. A high-throughput screening method for lithium-ion battery electrode materials based on single-particle electrochemical technology, characterized in that, Includes the following steps: S1. Preparation of spotted electrode: Prepare a conductive substrate, and deposit various lithium-ion battery electrode material sample solutions in an array on the same conductive substrate using an automatic spotting technique to form a microarray containing multiple independent deposition points. S2. Assembly and Optical Testing: The electrode sheet carrying the microarray is assembled with the counter electrode and electrolyte into an electrochemical testing unit; during the electrochemical charging and discharging process of the testing unit, the microarray is monitored in situ and synchronously using an optical imaging system to record the dynamic optical response signal of each deposition point. S3. Data Processing: Extract the optical response data corresponding to each deposition point or individual particle from the dynamic optical response signal, and obtain the electrochemical response parameters for evaluating the performance of the electrode material through fitting and statistical analysis.

2. The method according to claim 1, characterized in that, In step S1, the preparation of the conductive substrate specifically includes: mixing the conductive agent and the binder and then coating them onto the surface of the metal current collector, followed by drying.

3. The method according to claim 1, characterized in that, In step S1, the automatic spotting technology is performed using metal microneedles with a tip diameter of 40-60 μm; the diameter of each deposition point formed after spotting deposition is 80-120 μm.

4. The method according to claim 3, characterized in that, Each deposition point contains multiple independent electrode material particles, and the particles are spatially dispersed within the deposition point.

5. The method according to claim 1, characterized in that, In step S1, the lithium-ion battery electrode material sample solution is applied to the conductive substrate at preset coordinate positions using a program-controlled automatic spotting technique, so that the deposition points corresponding to different materials have an addressable spatial distribution in the microarray.

6. The method according to claim 1, characterized in that, In step S2, the electrochemical testing unit is a half-cell structure with lithium metal as the counter electrode.

7. The method according to claim 1, characterized in that, In step S2, the optical imaging system includes a microscopic imaging unit, a light source module, and a high-sensitivity detector, whose spatial resolution can distinguish particles at the micrometer to submicrometer scale.

8. The method according to claim 1, characterized in that, In step S2, the electrochemical charge-discharge is a constant current charge-discharge test.

9. The method according to claim 1, characterized in that, In step S2, the electrode material particles in all deposition points of the microarray are in the same electrochemical environment in the electrochemical testing unit, and through a synchronous optical monitoring process, the dynamic optical response signals of different material particles under the same charge and discharge conditions are obtained simultaneously, which are used to directly compare their intrinsic electrochemical characteristics.

10. The method according to claim 1, characterized in that, In step S3, the fitting is performed by fitting the optical intensity-voltage curve using the Lorentz function; The Lorentz function is: ; Among them, the peak position parameter x c The phase transition voltage of the corresponding electrode material particles; the peak width parameter w is used to reflect the sharpness of the electrochemical response process; the peak area A is used to characterize the response intensity; x represents the applied voltage value; y represents the single-particle optical response intensity measured corresponding to the applied voltage x; y0 represents the background optical signal or baseline optical intensity.

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