Battery cell test system based on lithium battery and test method thereof

Abstract

The invention relates to the technical field of testing of recycled battery cells, in particular to a battery cell testing system based on a lithium battery and a testing method thereof, a battery cell testing device is configured for testing the recycled battery cells, and the battery cell testing device is provided with a battery cell testing unit, an image acquisition module, an image processing module, a storage module and a main control module. The battery cell testing unit comprises a capturing plate, a plurality of testing stations are arranged on the capturing plate, and each testing station is provided with a sensor module, a testing connector and a battery cell testing module electrically connected to the testing connector; the image acquisition module comprises a visible light camera and a thermal imaging camera; synchronous detection of cells of multiple sizes and models is supported, the recycled cells do not need to be screened according to models in advance, direct feeding can be achieved only through primary screening of appearance and basic electrical performance, the outline of a visible light camera and multi-point feature recognition are combined, a data binding mechanism of one-time input and multi-time calling is matched, and the early-stage preparation time is greatly shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of testing of recycled battery cells, and in particular to a battery cell testing system based on lithium batteries and a testing method thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles, energy storage systems and consumer electronics industries, the number of retired power batteries, consumer electronic scrap batteries and production rework batteries has increased significantly. Some of these batteries have complete appearance and residual capacity, and can be used in low-speed electric vehicles, emergency power supplies and other scenarios after accurate detection, which has economic and environmental value.

[0003] However, the current recycling and rework battery detection technology has obvious bottlenecks and cannot meet the needs of large-scale production. First, the adaptability is poor. The types and models of recycled batteries cover a wide range, and the size and batch differences are large. The existing detection device sets the test parameter indicators of the battery cells uniformly, and needs to be adjusted manually for different types of battery cells. It cannot meet the "small batch, multiple frequency" scenario. Second, the dependence on manual work is high. The detection parameters of the battery cells are discrete, and the existing scheme needs to read the identification and input the test indicators manually, which is time-consuming and prone to parameter misrecording and feature omission, affecting the detection reliability. Third, the test coordination is insufficient. Thermal uniformity is a key indicator for the secondary use of battery cells. The existing technology often separates performance testing and thermal uniformity testing, or needs to transfer the battery cells and fix the point for data collection. This not only prolongs the detection period, but also leads to insufficient accuracy and the risk of thermal runaway of the battery cells flowing into the downstream.

[0004] In summary, the current testing and reuse technology for recycled and reworked battery cells has the problems of poor adaptability, high dependence on manual work, test disconnection and data fragmentation, which restricts the large-scale promotion of battery cell reuse. Therefore, there is an urgent need for a flexible testing technology to solve the above problems. SUMMARY

[0005] The present application is designed to provide a technical solution to solve the above problems.

[0006] A kind of lithium battery-based battery test system, configure battery test device for testing recycled battery, battery test device is provided with battery test unit, image acquisition module, image processing module, storage module and main control module, battery test unit includes capture board, multiple test stations are provided on capture board, and sensor module, test connector and battery test module electrically connected to test connector are configured on each test station;Image acquisition module includes visible light camera and thermal imaging camera;Image processing module includes visible light processing module and thermal imaging processing module, visible light processing module is used to analyze the features of visible light image, and thermal imaging processing module is used to extract temperature data from thermal imaging image;Storage module is used to store the detection data of battery, and detection data includes battery type parameter, test index parameter and historical detection result;Main control module is electrically connected with sensor module, battery test module, image acquisition module, image processing module and storage module respectively;Flexible test method of recycled battery includes the following steps.

[0007] Preferably, battery test module includes charge-discharge control unit, capacity calculation unit, internal resistance detection unit and cycle life timing unit;Charge-discharge control unit is used to adjust charge-discharge current and cutoff voltage according to the instruction of main control module, capacity calculation unit is used to calculate the actual capacity and SOH value of recycled battery, internal resistance detection unit is used to collect internal resistance data in real time during battery test process, and cycle life timing unit is used to record the number of cycle charge-discharge of battery and monitor capacity attenuation rate.

[0008] Preferably, capture board is provided with multiple layers, multiple test stations are uniformly distributed in each layer of capture board, linear module electrically connected to main control module is provided on each layer of capture board, visible light camera and thermal imaging camera are power-connected on linear module, and visible light camera and thermal imaging camera are moved to the corresponding position of any test station of the layer of capture board by driving linear module.

[0009] A kind of lithium battery-based battery test method, applied to the above-mentioned lithium battery-based battery test system, including the following steps: S1: preliminary screening, by screening out the battery after recycling with complete appearance and basic electrical performance, the battery with complete screening is transferred to the test station of capture board, and one battery is placed in each test station; S2: battery cell detection data acquisition, when the sensor module identifies that the battery cell is placed on the test station, a recognition signal is sent to the main control module; the main control module controls the visible light camera to collect the visible light image of the battery cell; the visible light processing module analyzes the features of the visible light image, extracts the battery cell contour and multi-point feature, generates a feature analysis result and sends it to the main control module; the main control module compares the feature analysis result with the storage data in the storage module to determine whether the storage module has historical detection data corresponding to the battery cell; if so, the corresponding detection data is retrieved and a testable prompt is issued; if not, an untestable prompt is issued; S3: performance test, after the testable prompt is issued, the battery cell is electrically connected with the test connector of the test station through the operator or the mechanical hand; the main control module sends a test instruction to the battery cell test module according to the retrieved detection data, calls the test index matched with the detection data, and detects the capacity and SOH of the battery cell, verifies the cycle life and detects the rate performance to determine whether the performance of the battery cell is qualified; S4: thermal uniformity test, during the cycle life verification and rate performance detection of S3, the main control module controls the thermal imaging camera to periodically collect the thermal imaging image of the battery cell; the thermal imaging processing module extracts the temperature data from the thermal imaging image, and determines the temperature distribution on the surface of the battery cell in combination with the battery cell contour output by the visible light processing module in S2; the maximum temperature difference value and the highest temperature value are calculated according to the temperature distribution, and compared with the test index parameters to determine whether the thermal uniformity performance of the battery cell is qualified; S5: battery cell classification and grouping, according to the performance test result of S3 and the thermal uniformity test result of S4, the battery cells qualified in both are retained, and the battery cells qualified in both are grouped; wherein, battery cells of different types are grouped according to the battery cell type parameter, and in the same type of battery cells, further grouping is performed according to the principle of "similar performance parameters", the capacity difference of the battery cells in the same group in the same type of battery cells is ≤3%-6%, the internal resistance difference is ≤5%-15%, and the SOH difference is ≤2%-4%.

[0010] Preferably, the feature analysis of the visible light processing module includes battery cell contour recognition and multi-point feature recognition; the battery cell contour recognition is used to extract the shape size parameter of the recovered battery cell, and the multi-point feature recognition is used to extract the tab position, shell identification and surface texture feature of the recovered battery cell.

[0011] Preferably, the specific process of capacity and SOH detection in S3 is: the charge-discharge control unit of the battery cell test module charges the recovered battery cell to the cut-off voltage at 0.5C rate, and then discharges to the cut-off voltage at 0.5C rate; the capacity calculation unit calculates the actual capacity according to the discharge curve, and calculates the SOH value according to the formula SOH=(actual capacity / nominal capacity)×100%.

[0012] Preferably, the thermal imaging processing module is further configured to coordinate match the extracted temperature data with the cell profile output by the visible light processing module, determine a temperature distribution map of the recovered cell surface, and calculate a maximum temperature difference value and a highest temperature value of a plurality of points in the temperature distribution map; wherein the plurality of points include a tab position, a cell corner position, and a cell center position.

[0013] Preferably, before the cell is tested, or after the untestable prompt is issued in S2, the corresponding detection data is entered by the technician according to the parameters of the cell, at the same time, the visible light processing module is driven by the main control module to collect images of the cell, the cell profile and the multi-point feature are extracted according to the collected visible light imaging, and the extracted multi-point feature is bound with the entered detection data based on the extracted multi-point feature, so that the extracted multi-point feature is used as the unique identification information for retrieving the corresponding detection data and the cell profile.

[0014] Preferably, in S5, the determination that both the SOH is greater than or equal to 80%, the capacity attenuation rate after 50 cycles is less than or equal to 10%, the peak temperature in the rate performance test is less than or equal to the preset maximum temperature threshold, and the maximum temperature difference is less than or equal to the preset temperature difference threshold.

[0015] Preferably, in S4, the periodic collection frequency of the thermal imaging camera is dynamically adjusted according to the test stage: the collection frequency is 1 time / 10 minutes in the cycle life verification stage, and the collection frequency is 1 time / 2 minutes in the rate performance test stage.

[0016] Compared with the prior art, the present application has the following advantages: Supports synchronous detection of multiple sizes and multiple models of cells, and the recovered cells do not need to be pre-screened by model, can be directly fed after preliminary screening of appearance and basic electrical performance, and the profile and multi-point feature recognition of the visible light camera are combined with the data binding mechanism of one-time entry and multiple-time calling to greatly shorten the preparation time, solve the pain points of frequent tool replacement and manual model screening in traditional detection; The technician can quickly identify the testable cells without checking the data one by one, and the cells without entered data can also be accurately screened, and the test is performed after the test data is entered, forming a data closed loop, completely solving the problem of fragmented data and easy-to-make mistakes in manual entry in traditional detection; In terms of automation and scene adaptability, the scheme supports manual semi-automatic operation, and can be upgraded to a fully automated system through adaptive test connectors, mechanical hands, and in-out conveying paths to meet the needs of different scale recycling enterprises; the grouping stage is based on clear double-qualified determination standards, i.e., SOH greater than or equal to 80% and cycle attenuation less than or equal to 10%, and performance parameters close to each other, i.e., capacity difference less than or equal to 3%-6%, to ensure accurate grouping and provide reliable guarantee for subsequent gradient utilization, and to realize high efficiency, low cost, and standardization of recovered cell detection as a whole; In the test efficiency and adaptability, through the multi-layer capture plate transverse distribution multiple test stations, each layer is equipped with only one set of linear module, visible light camera and thermal imaging camera, that is, the linear module drives the visible light camera and thermal imaging camera to move to complete the image acquisition of all test stations of the layer, which reduces the number of cameras and reduces the equipment cost and energy consumption.

[0017] Additional aspects and advantages of the application will be described in the following description, some of which will become apparent from the following description, or will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0019] Figure 1 is a structural schematic diagram of the battery cell testing device of the present application; Figure 2 is a method flow chart of the present application; Figure 3 is a circuit connection module block diagram of the single-layer capture plate of the present application; Figure 4 is a circuit connection module block diagram of the multi-layer capture plate of the present application.

[0020] The reference signs and names in the drawings are as follows: Battery cell test unit 10, capture plate 11, test station 12, sensor module 13, test joint 14, battery cell test module 15, linear module 16, image acquisition module 20, visible light camera 21, thermal imaging camera 22, image processing module 30, visible light processing module 31, thermal imaging processing module 32, storage module 40, main control module 50. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] Please refer to Figures 1-4The application embodiment provides a lithium battery-based cell testing system and a testing method thereof, and a cell testing device is configured to test recycled cells, and the cell testing device is provided with a cell testing unit 10, an image acquisition module 20, an image processing module 30, a storage module 40 and a main control module 50. The cell testing unit 10 comprises a capture plate 11, the capture plate 11 is provided with multiple layers, each layer of the capture plate 11 is horizontally and uniformly provided with multiple test stations 12, each layer of the capture plate 11 is provided with a linear module 16 electrically connected to the main control module 50, and each test station 12 is provided with a sensor module 13, a test connector 14 and a cell testing module 15 electrically connected to the test connector 14. The image acquisition module 20 comprises a visible light camera 21 and a thermal imaging camera 22, the visible light camera 21 and the thermal imaging camera 22 are both drivingly connected to the linear module 16, the visible light camera 21 and the thermal imaging camera 22 are driven to move to the corresponding positions of any test station 12 of the layer of the capture plate 11 by the linear module 16, the visible light camera 21 and the thermal imaging camera 22 do not need to be kept detecting all the time, one visible light camera 21 and one thermal imaging camera 22 are arranged on each layer of the capture plate 11, and thus the images of the cells in each test station 12 on the layer can be acquired; the image processing module 30 comprises a visible light processing module 31 and a thermal imaging processing module 32, the visible light processing module 31 is used for performing feature analysis on the visible light image, and the thermal imaging processing module 32 is used for extracting temperature data from the thermal imaging image; the storage module 40 is used for storing the detection data of the cells, the detection data comprises cell type parameters, test index parameters and historical detection results; the main control module 50 is electrically connected to the sensor module 13, the cell testing module 15, the image acquisition module 20, the image processing module 30 and the storage module 40 respectively; the main control module 50 comprises at least one upper computer and multiple lower computers, the upper computer and the lower computers realize data transmission through data lines or switches, and each lower computer is connected to all the cell testing modules 15 on each layer of the capture plate 11, so that the whole cell testing device can be uniformly controlled by the upper computer. Please refer to Figure 2 The flexible testing method of the recycled cells comprises the following steps: S1: preliminary screening, the cells with complete appearance and complete basic electrical performance after recycling are screened out, the screened cells are transferred to the test stations 12 of the capture plate 11 for pre-placement, one cell is placed on each test station 12, the purpose of the design is that an operator or a mechanical hand can quickly place the cells of the same recycling batch on the test stations 12, and the cells are identified by the visible light camera 21; that is, as long as the appearance integrity and the basic electrical performance integrity of the recycled cells are detected, the cells can be directly transferred to the equipment for testing, and the types of the cells do not need to be screened; S2: The battery cell detection data acquisition, when the sensor module 13 identifies that the test station 12 is placed on the battery cell, the identification signal is sent to the main control module 50; the main control module 50 controls the visible light camera 21 to collect the visible light image of the battery cell; the visible light processing module 31 analyzes the features of the visible light image, the feature analysis of the visible light processing module 31 includes battery cell contour recognition and multi-point feature recognition; the battery cell contour recognition is used to extract the size parameters of the recycled battery cell, and the multi-point feature recognition is used to extract the tab position, shell identification and surface texture features of the recycled battery cell; for some special-shaped battery cells, only the battery cell contour recognition can be used to determine the type of the battery cell; for some battery cells with the same size profile but different parameters, the appearance features of the battery cell need to be identified. After extracting the battery cell contour and multi-point features, the feature analysis result is generated and sent to the main control module 50; the main control module 50 compares the feature analysis result with the storage data of the storage module 40 to determine whether the storage module 40 has historical detection data corresponding to the battery cell; if it exists, the corresponding detection data is retrieved, and a testable prompt is issued; if it does not exist, an untestable prompt is issued, specifically, an indicator light can be configured on the corresponding test station 12, when the indicator light shows green, it means that the testable prompt is issued, when the indicator light shows red, it means that the untestable prompt is issued, the technician can directly connect the battery cell with the test connector 14 according to the green indicator light, in this way, the technician can quickly connect and test the battery cell that has been recorded in the system, and the battery cell whose detection data has not been recorded in the system can also be quickly screened out, and after further recording by the technician, it can be tested, realizing a one-time recording and multiple calls to solve the data fragmentation problem. Specifically, before the battery cell is tested, or after the untestable prompt is issued in S2, the corresponding detection data is recorded by the technician according to the parameters of the battery cell, at the same time, the main control module 50 drives the visible light processing module 31 to collect the image of the battery cell, extracts the battery cell contour and multi-point features according to the collected visible light image, and binds the extracted multi-point features with the recorded detection data, so that the extracted multi-point features are used as the unique identification information of the corresponding detection data and battery cell contour; that is, in this way, one-time recording and multiple calls can be realized, and when the same type of battery cell is tested subsequently, the system can automatically retrieve the corresponding detection data without frequent modification by the technician.

[0023] S3: Performance test, after issuing a testable prompt, the battery cell is electrically connected with the test connector 14 of the test station 12 by the operator or the mechanical hand; the main control module 50 sends a test instruction to the battery cell test module 15 according to the detection data, calls the test index matched with the detection data, detects the capacity and SOH (state of health) of the battery cell, verifies the cycle life and detects the rate performance, and determines whether the performance of the battery cell is qualified; That is, on the basis of solving the data fragmentation problem by entering the detection data, the battery cell test module 15 is further designed to be integrated, so that the battery cell test module 15 can test the battery cell in multiple steps, and the recovered battery cell can be uniformly tested; wherein the battery cell test module 15 includes a charge-discharge control unit, a capacity calculation unit, an internal resistance detection unit and a cycle life timing unit; the charge-discharge control unit is used to adjust the charge-discharge current and the cutoff voltage according to the instruction of the main control module 50, the capacity calculation unit is used to calculate the actual capacity and SOH value of the recovered battery cell, the internal resistance detection unit is used to collect the internal resistance data in real time during the battery cell test process, and the cycle life timing unit is used to record the number of cycle charge-discharge times of the battery cell and monitor the capacity attenuation rate; The specific process of capacity and SOH detection is that the charge-discharge control unit of the battery cell test module 15 charges the recovered battery cell to the cutoff voltage at 0.5C rate, and then discharges to the cutoff voltage at 0.5C rate; the capacity calculation unit calculates the actual capacity according to the discharge curve, and calculates the SOH value according to the formula SOH=(actual capacity / nominal capacity)×100%.

[0024] S4: Thermal uniformity test, during the cycle life verification and rate performance detection stage of S3, the main control module 50 controls the thermal imaging camera 22 to periodically collect the thermal imaging image of the battery cell, and the periodic collection frequency of the thermal imaging camera 22 is dynamically adjusted according to the test stage: the collection frequency is 1-2 times / 10 minutes during the cycle life verification stage, and generally 1 time / 10 minutes; the collection frequency is 1-2 times / 2 minutes during the rate performance detection stage, and generally 1 time / 2 minutes.

[0025] After collecting the thermal imaging image, the thermal imaging processing module 32 extracts the temperature data of the thermal imaging image, and determines the temperature distribution of the surface of the battery cell in combination with the battery cell contour output by the visible light processing module 31 in S2; according to the temperature distribution, the maximum temperature difference value and the highest temperature value are calculated, which are compared with the test index parameters to determine whether the thermal uniformity performance of the battery cell is qualified; Wherein, the thermal imaging processing module 32 is used to match the extracted temperature data with the battery cell contour output by the visible light processing module 31 to determine the temperature distribution atlas of the surface of the recovered battery cell, and calculate the maximum temperature difference value and the highest temperature value of multiple points in the temperature distribution atlas; the multiple points include the lug position, the battery cell corner position and the battery cell center position.

[0026] S5: cell classification grouping, according to the performance test results of S3 and the thermal uniformity test results of S4, the cells that meet both are retained, and the specific judgment is: SOH≥80%, capacity attenuation rate≤10% after 50 cycles, peak temperature≤preset maximum temperature threshold in rate performance test and maximum temperature difference≤preset temperature difference threshold; The cells that meet both are grouped; wherein, according to the cell type parameter, the cells of different types are grouped, and in the same type of cells, further grouping is performed according to the principle of "similar performance parameters", the capacity difference of the same group of cells in the same type of cells is≤3%-6%, the internal resistance difference is≤5%-15%, and the SOH difference is≤2%-4%; The system can configure a display screen module to display the cell parameters after testing, so that the operator or the mechanical hand can group the cells according to the cell parameters after testing.

[0027] In the above flexible test method of the recycled cells, by configuring a cell testing device with multiple test stations 12, the visible light camera 21 is used to recognize the cell profile and multi-point feature of different models and sizes of cells, and the detection data is input in advance or temporarily, so that the recycled and reworked cells do not need to be pre-classified and grouped, and the data closed loop can be realized by one-time input and multiple calls to solve the data fragmentation problem; The visible light camera 21 can also be used to scan the cell profile, and the thermal imaging camera 22 can be used to collect the surface temperature distribution information of the cell during the test process, so that the thermal uniformity of the cell can be tested simultaneously during the cell performance test; In addition, the test of each cell in the whole process is independent, and after the test is completed, the cell can be taken out immediately for testing of the next cell, which greatly improves the flexibility; The method can be operated semi-automatically by manual operation, and can also be automatically operated by adapting the test connector 14, combined with the structure of the mechanical hand, the feeding conveying path and the multiple discharging conveying paths.

[0028] In addition, when collecting cell image information by using the visible light camera 21 and the thermal imaging camera 22, considering that it is not necessary to continuously collect images of a single cell, the technical solution further adopts a multi-layer capture plate 11 and a plurality of test stations 12 arranged transversely on the capture plate 11, and then uses a linear module 16 on each layer of capture plate 11, so that only one visible light camera 21 and one thermal imaging camera 22 are arranged on each layer of capture plate 11, which can reduce the number of cameras and to a certain extent, simplify the equipment cost and equipment energy consumption.

[0029] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A lithium battery based cell testing system, characterized by, The battery cell testing device is configured for testing the recycled battery cell, and is provided with a battery cell testing unit (10), an image acquisition module (20), an image processing module (30), a storage module (40) and a main control module (50). The battery cell testing unit (10) comprises a capture plate (11), a plurality of test stations (12) are arranged on the capture plate (11), and a sensor module (13), a test connector (14) and a battery cell testing module (15) electrically connected to the test connector (14) are arranged on each test station (12). The image acquisition module (20) comprises a visible light camera (21) and a thermal imaging camera (22). The image processing module (30) comprises a visible light processing module (31) and a thermal imaging processing module (32), the visible light processing module (31) is used for feature analysis of visible light images, and the thermal imaging processing module (32) is used for temperature data extraction of thermal imaging images. The storage module (40) is used for storing detection data of the battery cell, and the detection data comprises battery cell type parameters, test index parameters and historical detection results. The main control module (50) is electrically connected with the sensor module (13), the battery cell testing module (15), the image acquisition module (20), the image processing module (30) and the storage module (40).

2. The lithium battery-based cell testing system of claim 1, wherein, The battery cell testing module (15) comprises a charge-discharge control unit, a capacity calculation unit, an internal resistance detection unit and a cycle life timing unit. The charge-discharge control unit is used for adjusting the charge-discharge current and the cutoff voltage according to the instruction of the main control module (50). The capacity calculation unit is used for calculating the actual capacity and SOH value of the recycled battery cell. The internal resistance detection unit is used for real-time acquisition of internal resistance data in the battery cell testing process. The cycle life timing unit is used for recording the number of cycle charge-discharge times of the battery cell and monitoring the capacity attenuation rate.

3. The lithium battery-based cell testing system of claim 1, wherein, The capture plate (11) is provided with multiple layers, and a plurality of test stations (12) are uniformly distributed in each layer of the capture plate (11). A linear module (16) electrically connected to the main control module (50) is arranged on each layer of the capture plate (11). The visible light camera (21) and the thermal imaging camera (22) are power-connected to the linear module (16). The visible light camera (21) and the thermal imaging camera (22) are moved to the corresponding positions of any test station (12) in the layer of the capture plate (11) by the linear module (16).

4. A method for testing a lithium battery-based cell applied to the lithium battery-based cell testing system of any one of claims 1-3, characterized in that The method comprises the following steps: S1: preliminary screening, by screening the battery cell with complete appearance and complete basic electrical performance after recycling, and transferring the screened complete battery cell to the test station (12) of the capture plate (11), and placing one battery cell in each test station (12); S2: The battery cell detection data acquisition, when the sensor module (13) identifies that the test station (12) is placed on the battery cell, sends an identification signal to the main control module (50); the main control module (50) controls the visible light camera (21) to collect the visible light image of the battery cell; the visible light processing module (31) analyzes the features of the visible light image, extracts the battery cell contour and multi-point feature, generates a feature analysis result and sends it to the main control module (50); The main control module (50) compares the feature analysis result with the storage data of the storage module (40) to determine whether the storage module (40) has historical detection data corresponding to the battery cell; if so, the corresponding detection data is retrieved, and a testable prompt is issued; if not, an untestable prompt is issued; S3: Performance test, after issuing the testable prompt, the battery cell is electrically connected with the test connector (14) of the test station (12) through the operator or the mechanical hand; the main control module (50) sends a test instruction to the battery cell test module (15) according to the retrieved detection data, calls the test index matched with the detection data, and detects the capacity and SOH of the battery cell, verifies the cycle life and detects the rate performance to determine whether the performance of the battery cell is qualified; S4: Thermal uniformity test, during the cycle life verification and rate performance detection of S3, the main control module (50) controls the thermal imaging camera (22) to periodically collect the thermal imaging image of the battery cell; the thermal imaging processing module (32) extracts the temperature data from the thermal imaging image, and determines the temperature distribution on the surface of the battery cell in combination with the battery cell contour output by the visible light processing module (31) in S2; According to the temperature distribution, the maximum temperature difference value and the highest temperature value are calculated, and compared with the test index parameters to determine whether the thermal uniformity performance of the battery cell is qualified; S5: Battery cell classification and grouping, according to the performance test results of S3 and the thermal uniformity test results of S4, the battery cells qualified in both are retained, and the battery cells qualified in both are grouped; wherein, according to the battery cell type parameters, different types of battery cells are grouped, and in the same type of battery cells, further grouping is performed according to the principle of "similar performance parameters", the capacity difference of the same group of battery cells in the same type of battery cells is ≤3%-6%, the internal resistance difference is ≤5%-15%, and the SOH difference is ≤2%-4%.

5. The method of claim 4, wherein the lithium battery-based cell testing method further comprises: The feature analysis of the visible light processing module (31) includes battery cell contour recognition and multi-point feature recognition; the battery cell contour recognition is used to extract the shape size parameters of the recovered battery cell, and the multi-point feature recognition is used to extract the tab position, shell identification and surface texture features of the recovered battery cell.

6. The method of claim 4, wherein the lithium battery cell is a lithium-ion battery cell. The specific process of capacity and SOH detection in S3 is: the charge and discharge control unit of the battery cell test module (15) charges the recovered battery cell to the cut-off voltage at 0.5C rate, and then discharges to the cut-off voltage at 0.5C rate; the capacity calculation unit calculates the actual capacity according to the discharge curve, and calculates the SOH value according to the formula SOH=(actual capacity / nominal capacity)×100%.

7. The method of claim 4, wherein the lithium battery-based cell testing method further comprises: The thermal imaging processing module (32) is further configured to coordinate match the extracted temperature data with the cell contour output by the visible light processing module (31), determine a temperature distribution atlas of the recovered cell surface, and calculate a maximum temperature difference value and a highest temperature value of a plurality of points in the temperature distribution atlas; wherein the plurality of points include a tab position, a cell corner position, and a cell center position.

8. The method of claim 4, wherein the lithium battery-based cell testing method further comprises: Before the cell is tested, or after the untestable prompt is issued in S2, the corresponding detection data is entered by the technician according to the parameters of the cell, and at the same time, the visible light processing module (31) is driven by the main control module (50) to collect images of the cell, the cell contour and the multi-point feature are extracted according to the collected visible light imaging, and the extracted multi-point feature is bound with the entered detection data based on the extracted multi-point feature, so that the extracted multi-point feature is used as the unique identification information for retrieving the corresponding detection data and the cell contour.

9. The method of claim 4, wherein the lithium battery-based cell testing method further comprises: In S5, the determination that the cell is qualified in both aspects is that SOH≥80%, the capacity attenuation rate after 50 cycles is ≤10%, the peak temperature in the rate performance detection is ≤ the preset highest temperature threshold, and the maximum temperature difference is ≤ the preset temperature difference threshold.

10. The method of claim 4, wherein the lithium battery-based cell testing method further comprises: In S4, the periodic collection frequency of the thermal imaging camera (22) is dynamically adjusted according to the test stage: the collection frequency is 1 time / 10 minutes in the cycle life verification stage, and the collection frequency is 1 time / 2 minutes in the rate performance detection stage.

Images