Battery cell ocv testing and sorting apparatus and method

Abstract

The application discloses a kind of battery OCV test sorting equipment and method, comprising: rack;Feeding conveying mechanism, it is arranged in rack one side;Detection station, it is arranged at the discharge port of feeding conveying mechanism;Battery OCV test mechanism, it is set above detection station, including output vertical downward setting linear driver above detection station, the linear driver output end is provided with mounting seat, the mounting seat relative two sides are respectively provided with self-cleaning probe contact component;Discharge sorting mechanism, it is connected with the discharge port of detection station, to sort battery;Wherein, the self-cleaning probe component includes kelvin probe and is used to scrape off the oxide layer of battery tab surface before kelvin probe contacts battery tab self-cleaning component.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, specifically to a cell OCV testing and sorting device and method. Background Technology

[0002] In the final stages of lithium-ion cell production, the manufacturing quality and consistency checks of the cells are crucial. After electrolyte filling, formation, capacity testing, and settling, the open-circuit voltage (OCV) and AC internal resistance (ACIR) of the cells must be precisely measured to identify defective products and sort them into groups (such as A-grade, B-grade, and scrap).

[0003] Existing battery cell OCV testing equipment often faces unstable contact resistance in actual operation. Specifically, the tabs of the battery cell (especially aluminum tabs and copper-nickel tabs) are very easy to oxidize in the air, forming a dense oxide film. When conventional test probes directly press against the contact, it is difficult to pierce the oxide layer, resulting in a large and unstable contact resistance, which seriously affects the measurement accuracy of AC internal resistance (ACIR) and OCV.

[0004] Therefore, the present invention urgently needs to solve the problem of providing a battery cell OCV testing and sorting device and method that can automatically scrape off the oxide layer by probe contact to improve measurement accuracy. Summary of the Invention

[0005] To address the aforementioned technical problems, the purpose of this invention is to overcome the unstable contact resistance often encountered in existing battery cell OCV testing equipment during actual operation. Specifically, because the tabs of the battery cell (especially aluminum and copper-nickel tabs) are highly susceptible to oxidation in air, forming a dense oxide film, conventional test probes struggle to pierce this oxide layer when directly pressing against it, resulting in high and highly unstable contact resistance, severely impacting the measurement accuracy of AC internal resistance (ACIR) and OCV. Therefore, this invention provides a battery cell OCV testing and sorting device and method that can automatically scrape off the oxide layer upon probe contact, thereby improving measurement accuracy.

[0006] To achieve the above objectives, the present invention provides a battery cell OCV testing and sorting device, comprising: a frame; a feeding and conveying mechanism disposed on one side of the frame; a testing station disposed at the outlet of the feeding and conveying mechanism; a battery cell OCV testing mechanism disposed above the testing station, including a linear driver with its output end vertically downward disposed above the testing station, the output end of the linear driver being provided with a mounting base, and self-cleaning probe contact assemblies being respectively disposed on opposite sides of the mounting base; and a feeding and sorting mechanism docking with the outlet of the testing station for sorting the battery cells; wherein, the self-cleaning probe assembly includes a Kelvin probe and a self-cleaning component for scraping off the oxide layer on the surface of the battery cell tab before the Kelvin probe contacts the battery cell tab.

[0007] Preferably, the self-cleaning component includes: a fixed sleeve disposed on a mounting base and having a Kelvin probe inside; a floating sleeve and a first elastic element, wherein the floating sleeve is coaxially and telescopically disposed within the fixed sleeve via the first elastic element, the fixed sleeve having a spiral groove, and the floating sleeve having a guide pin adapted to the spiral groove; and a scraper assembly disposed at the lower end of the floating sleeve.

[0008] Preferably, the scraper assembly includes: a movable scraper, wherein the lower end of the floating sleeve has mounting grooves on opposite sides, and the movable scraper is provided on opposite sides of the mounting grooves in a reciprocating manner; a guide rod, wherein a guide rod is provided through each movable scraper in each mounting groove; and a second elastic element, wherein a second elastic element is sleeved on opposite sides of each guide rod, wherein one end of the second elastic element abuts or is fixed to the movable scraper, and the other end abuts or is fixed to the inner wall of the mounting groove.

[0009] Preferably, each movable scraper is provided with a guide ramp on its upper side.

[0010] Preferably, the feeding and conveying mechanism includes: a first conveyor belt disposed on one side of the frame; a transfer mechanism disposed at the output end of the first conveyor belt; the detection station includes: a second conveyor belt disposed at the output end of the transfer mechanism; a photoelectric switch disposed on one side of the second conveyor belt; the unloading and sorting mechanism includes: a third conveyor belt, with a plurality of third conveyor belts arranged side by side on one side of the second conveyor belt; a sorting conveyor platform and a linear module, wherein the sorting conveyor platform is reciprocally disposed on one side of the second and third conveyor belts via the linear module.

[0011] And a cell OCV testing and sorting method, characterized by comprising the following steps: S1. The first conveyor belt transports the battery cells to be tested. Then, the transfer mechanism transfers the battery cells on the first conveyor belt one by one to the second conveyor belt of the testing station. The second conveyor belt serves as the carrier of the testing station and drives the battery cells forward. When the photoelectric switch on the side detects that the battery cell has reached the preset test position, the control system immediately triggers the second conveyor belt to stop, so that the battery cell stops precisely under the battery cell OCV testing mechanism. S2. The output of the linear actuator extends vertically downwards, and the two sets of self-cleaning probe contact components descend synchronously. The closed-state moving scraper first touches the surface of the corresponding cell tab. The tab generates an upward supporting reaction force on the scraper. The mounting base continues to descend, and the reaction force of the tab pushes the floating sleeve to overcome the elastic force of the first elastic element and retract upwards along the inside of the fixed sleeve. The guide pin on the floating sleeve climbs upwards along the spiral groove on the inner wall of the fixed sleeve. The trajectory of the spiral groove constrains the guide pin to generate circumferential rotation, which in turn drives the entire floating sleeve and the scraper assembly at the lower end to retract upwards while rotating circumferentially around the sleeve axis. The closed-state moving scraper keeps close to the surface of the tab and performs circular rotation scraping. Through mechanical friction, the dense oxide film, dust, and oil on the surface of the tab are completely removed, exposing the pure metal substrate. This eliminates the contact resistance fluctuations caused by the oxide layer from the root. The floating sleeve continues to retract upwards, and the internal fixed... The Kelvin probe moves downward relative to the floating sleeve. The lower end of the probe contacts the guide ramp on the inner side of the two moving scrapers. As the probe continues to descend, the vertical downward pressure is decomposed into a horizontal outward component along the guide ramp. This gradually pushes the two moving scrapers to slide outward synchronously along the guide rod, compressing the second elastic elements on both sides. The scrapers open to both sides at a uniform speed without any rigid impact. When the floating sleeve retracts to its limit stroke, the Kelvin probe extends completely from the opening between the two moving scrapers and presses precisely into the center area of ​​the cleaned electrode tab with the set pressure. The two sets of Kelvin probes conduct synchronously, forming a complete four-wire test circuit. The test system starts and, through the Kelvin test principle of separating the current circuit and the voltage sampling circuit, eliminates the interference of lead resistance and contact resistance on voltage acquisition, completing the high-precision measurement of the cell open circuit voltage (OCV). It can also simultaneously complete the AC internal resistance (ACIR) detection. S3. During the measurement process, the Kelvin test probe reads the original value of the open circuit voltage Vraw and the original value of the AC internal resistance Rraw of the cell. At the same time, the non-contact infrared temperature measurement component built into the equipment control system measures the actual value of the current surface temperature Tc of the cell in real time. S4. The main control system corrects the measured values ​​based on the actual values ​​of the battery cells collected and the preset mathematical model of battery cell temperature characteristics, and calculates the corrected voltage value V25 and the corrected internal resistance value R25 at the standard temperature of 25℃. S5. After the test is completed, the OCV testing mechanism moves upward and resets, and the second conveyor belt restarts, transporting the tested battery cells to the discharge end, waiting to enter the sorting process. The discharge end of the second conveyor belt connects to the sorting conveyor table, and the tested battery cells are directly transported to the sorting conveyor table for temporary storage. The sorting conveyor table itself has conveying capacity and can complete the input and output of battery cells. According to the battery cell grade obtained from the test, such as grade A, grade B, defective, etc., the control system drives the linear module to move the sorting conveyor table laterally back and forth, accurately aligning it with the third conveyor belt of the corresponding grade. After alignment, the sorting conveyor table starts conveying, sending the battery cells into the corresponding third conveyor belt, flowing to the subsequent process or the corresponding material box. Then the linear module drives the sorting conveyor table to reset to the discharge end of the second conveyor belt to receive the next battery cell, and the cycle repeats to complete the grading and sorting of batch battery cells.

[0012] Preferably, the temperature compensation correction calculation formula in step S4 is as follows: V25 = Vraw - α * (Tc - 25) R25 = Rraw * [1 - β * (Tc - 25)].

[0013] Preferably, the open-circuit voltage temperature coefficient α and the internal resistance temperature coefficient β are obtained by the following calibration method: randomly select sample cells from the same batch, set multiple temperature gradient points Ti in a controlled constant temperature chamber, and after being kept at a constant temperature at each temperature gradient point for more than a set time, measure the corresponding steady-state open-circuit voltage value V(Ti) and steady-state internal resistance value R(Ti), and use the least squares method to perform linear or polynomial fitting, and calculate the slopes respectively, which are the coefficients α and β.

[0014] Preferably, the temperature compensation correction in step S4 further includes: the main control system compares the actual temperature values ​​Tc of multiple adjacent cells measured by the same test position in real time. If the temperature change value ΔTc=|Tc,n-Tc,n-1| of adjacent tests exceeds 3℃, the main control system determines that there is a contact abnormality or temperature sensing obstruction at the test position, sends an alarm signal, and automatically marks the measured cell as a position to be re-inspected.

[0015] According to the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows: The two sets of self-cleaning probe contact assemblies on opposite sides of the mounting base of this application descend synchronously. The self-cleaning assembly contacts the surface of the battery cell tab before the Kelvin probe, and removes the oxide film on the surface of the tab through mechanical scraping to expose the clean metal substrate. The mounting base continues to descend to the test position, and the Kelvin probe is pressed tightly on the cleaned tab area with a set pressure. Based on the Kelvin four-wire test principle, the current loop and the voltage sampling loop are separated, eliminating the interference of lead resistance and contact resistance on voltage acquisition, and completing the high-precision measurement of the battery cell open circuit voltage OCV.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section; and all parts not covered in the present invention are the same as or can be implemented using the prior art. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a perspective view of a battery cell OCV testing and sorting device provided in a preferred embodiment of the present invention; Figure 2 This is a partial three-dimensional view of the cell OCV testing and sorting equipment provided in a preferred embodiment of the present invention. Figure 1 ; Figure 3 This is a partial three-dimensional view of the cell OCV testing and sorting equipment provided in a preferred embodiment of the present invention. Figure 2 ; Figure 4 This is a partial three-dimensional view of the cell OCV testing and sorting equipment provided in a preferred embodiment of the present invention. Figure 3 ; Figure 5 This is a partial planar cross-sectional view of a battery cell OCV testing and sorting device provided in a preferred embodiment of the present invention; Figure 6 This is a partial exploded view of a battery cell OCV testing and sorting device provided in a preferred embodiment of the present invention; Figure 7 This is a partial three-dimensional view of the cell OCV testing and sorting equipment provided in a preferred embodiment of the present invention. Figure 4 ; Figure 8 This is a partial three-dimensional view of the cell OCV testing and sorting equipment provided in a preferred embodiment of the present invention. Figure 5 ; Figure 9 This is a flowchart of a preferred embodiment of the present invention for a cell OCV testing and sorting method.

[0018] Explanation of reference numerals in the attached drawings: 1. Frame; 2. Feeding and conveying mechanism; 21. First conveyor belt; 22. Transfer mechanism; 3. Inspection station; 31. Second conveyor belt; 32. Photoelectric switch; 4. OCV testing mechanism; 41. Linear driver; 42. Mounting base; 43. Self-cleaning probe contact assembly; 431. Kelvin probe; 432. Self-cleaning assembly; 4321. Fixed sleeve; 43211. Spiral groove; 4322. Floating sleeve; 43221. Guide pin; 43222. Mounting groove; 4323. First elastic element; 4324. Scraper assembly; 43241. Moving scraper; 432411. Guide ramp; 43242. Guide rod; 43243. Second elastic element; 5. Unloading and sorting mechanism; 51. Third conveyor belt; 52. Sorting and conveying table; 53. Linear module. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] In the description of the embodiments of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance. Additionally, the terms "horizontal," "vertical," and "suspended," etc., do not indicate that the component is required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0021] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0022] To further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0023] Reference Figures 1-4 A battery cell OCV testing and sorting device includes: a frame 1; a feeding conveyor 2 disposed on one side of the frame 1; a testing station 3 disposed at the outlet of the feeding conveyor 2; a battery cell OCV testing mechanism 4 disposed above the testing station 3, including a linear driver 41 with its output end vertically downward disposed above the testing station 3, the output end of the linear driver 41 being provided with a mounting base 42, and self-cleaning probe contact components 43 respectively disposed on opposite sides of the mounting base 42; and a feeding and sorting mechanism 5 connected to the outlet of the testing station 3 for sorting the battery cells; wherein the self-cleaning probe component includes a Kelvin probe 431 and a self-cleaning component 432 for scraping off the oxide layer on the surface of the battery cell tab before the Kelvin probe 431 contacts the battery cell tab.

[0024] In this application, the two sets of self-cleaning probe contact assemblies 43 on opposite sides of the mounting base 42 descend synchronously. The self-cleaning assembly 432 contacts the surface of the cell tab before the Kelvin probe 431, and removes the oxide film on the surface of the tab through mechanical scraping, exposing the clean metal substrate. The mounting base 42 continues to descend to the test position, and the Kelvin probe 431 presses against the cleaned tab area with a set pressure. Based on the Kelvin four-wire test principle, the current loop and the voltage sampling loop are separated, eliminating the interference of lead resistance and contact resistance on voltage acquisition, and completing the high-precision measurement of the cell open circuit voltage OCV.

[0025] Reference Figures 4-7 The self-cleaning component 432 includes: a fixed sleeve 4321, which is mounted on the mounting base 42 and has a Kelvin probe 431 inside; a floating sleeve 4322 and a first elastic element 4323, wherein the floating sleeve 4322 is coaxially and telescopically mounted inside the fixed sleeve 4321 through the first elastic element 4323, the fixed sleeve 4321 has a spiral groove 43211 inside, and the floating sleeve 4322 has a guide pin 43221 adapted to the spiral groove 43211; and a scraper assembly 4324, which is mounted at the lower end of the floating sleeve 4322.

[0026] The first elastic element 4323 pushes the floating sleeve 4322 downward, making the bottom surface of the lower scraper assembly 4324 lower than the tip of the internal Kelvin probe 431. The guide pin 43221 is engaged in the spiral groove 43211 of the fixed sleeve 4321, and the scraper maintains its initial circumferential angle. The linear actuator 41 drives the mounting base 42 and the entire self-cleaning assembly 432 to move vertically downward. The scraper assembly 4324 first touches the surface of the battery cell tab, and the tab generates an upward reaction force on the scraper. During the continuous downward movement, the tab prevents the scraper from retracting upward, and the floating sleeve... 4322 overcomes the elastic force of the first elastic element 4323 and retracts upward along the inside of the fixed sleeve 4321. The guide pin 43221 on the floating sleeve 4322 climbs along the spiral groove 43211 of the fixed sleeve 4321. The spiral groove 43211 constrains the guide pin 43221 to generate circumferential rotation, which drives the lower scraper assembly 4324 to retract upward while rotating around the coaxial center. The scraper rotates and rubs against the surface of the electrode tab, and thoroughly peels off the dense oxide film, dust and oil on the surface of the aluminum or copper electrode tab through circumferential ring scraping, exposing the pure metal substrate.

[0027] Reference Figure 7 The scraper assembly 4324 includes: a movable scraper 43241, wherein the lower end of the floating sleeve 4322 has mounting grooves 43222 on opposite sides, and the movable scraper 43241 is provided on opposite sides of the mounting grooves 43222 in a reciprocating manner; a guide rod 43242, wherein a guide rod 43242 is provided through each movable scraper 43241 in each mounting groove 43222; and a second elastic element 43243, wherein a second elastic element 43243 is sleeved on opposite sides of each guide rod 43242, wherein one end of the second elastic element 43243 abuts or is fixed to the movable scraper 43241, and the other end abuts or is fixed to the inner wall of the mounting groove 43222.

[0028] In this application, mounting grooves 43222 are formed on opposite sides of the open lower end of the floating sleeve 4322. A guide rod 43242 is fixedly inserted through each groove. The two ends of the movable scraper 43241 are slidably sleeved on the guide rod 43242. A second elastic element 43243, usually a compression spring, is sleeved on both sides of the guide rod 43242. One end of the second elastic element 43243 abuts against the inner wall of the mounting groove 43222, and the other end abuts against the movable scraper 43241. In the free state, the second elastic element 43243 pushes the two movable scrapers inward. The blade 43241 keeps the two scrapers closed at the opening of the sleeve, forming a complete scraping end face. At this time, the bottom surface of the closed scraper is lower than the tip of the internal Kelvin probe 431, ensuring that the scraper contacts the electrode tab first when pressed down. The entire assembly moves downward with the linear actuator 41. The closed moving scraper 43241 first abuts against the surface of the battery cell electrode tab. As the floating sleeve 4322 retracts upward against the first elastic element 4323, the guide pin 43221 drives the floating sleeve 4322 to rotate circumferentially along the spiral groove 43211, maintaining the closed moving scraper. The scraper 43241 scrapes the surface of the tab in a circular motion, completely removing the oxide film, oil, and dust. During this stage, the second elastic element 43243 continuously provides a closing force, preventing the scraper from opening on its own and ensuring a complete scraping area and uniform contact pressure. The floating sleeve 4322 continues to retract, and the Kelvin probe 431 fixed inside moves downward relative to the floating sleeve 4322. The lower end of the probe acts on the inner side of the two moving scrapers 43241, pushing the two moving scrapers 43241 to slide outward synchronously along the guide rod 43242. The second elastic element 43243 is compressed, and the scraper opens to both sides. Finally, the Kelvin probe 431 extends from the opening between the two scrapers and is precisely pressed against the center area of ​​the tab that has just been cleaned. An OCV test is performed. After the test is completed, the mechanism moves upward, and the Kelvin probe 431 is lifted with the mounting base 42. The pushing force on the moving scraper 43241 disappears, the second elastic element 43243 releases its elasticity, and pushes the moving scrapers 43241 on both sides to slide inward along the guide rod 43242 to reset and return to the closed state, waiting for the next cleaning cycle.

[0029] Reference Figure 8 Each movable scraper 43241 has a guide ramp 432411 inclined on its upper side.

[0030] In the free state, the second elastic element 43243 pushes the two movable scrapers 43241 inward along the guide rod 43242 to engage, maintaining a closed state. The guide ramps 432411 of the two movable scrapers 43241 are symmetrically inclined, forming a flared guide surface that is narrow at the top and wide at the bottom. At this time, the bottom surface of the closed scraper is lower than the tip of the internal Kelvin probe 431, ensuring that the scraper contacts the battery cell tab first when descending. As the probe continues to descend, the vertically downward pressure is decomposed along the slope of the guide ramp 432411. The horizontal outward force pushes the two moving scrapers 43241 to slide outward synchronously along the guide rod 43242, compressing the second elastic element 43243. The scrapers open to both sides at a constant speed. When the floating sleeve 4322 retracts to its limit position, the Kelvin probe 431 extends fully from the opening between the two scrapers and presses precisely against the center area of ​​the electrode tab that has just been cleaned, performing OCV high-precision testing. The inclined plane transmission is a progressive force application. The moving scraper 43241 opens at a constant speed as the probe descends, without any sudden rigid impact.

[0031] Reference Figure 2 The feeding and conveying mechanism 2 includes: a first conveyor belt 21, which is disposed on one side of the frame 1; and a transfer mechanism 22, which is disposed at the output end of the first conveyor belt 21. The detection station 3 includes: a second conveyor belt 31, which is disposed at the output end of the transfer mechanism 22; and a photoelectric switch 32, which is disposed on one side of the second conveyor belt 31. The material sorting mechanism 5 includes: a third conveyor belt 51, with several third conveyor belts 51 arranged side by side on one side of the second conveyor belt 31; a sorting conveyor platform 52 and a linear module 53, wherein the sorting conveyor platform 52 is arranged on one side of the second conveyor belt 31 and the third conveyor belt 51 through the linear module 53.

[0032] The first conveyor belt 21 is arranged on the side of the frame 1 to receive the battery cells to be tested from the upstream process or manually loaded. It transports the battery cells to the output end in a continuous conveying manner, realizing the buffering and feeding of batch battery cells. The transfer mechanism 22 is set between the output end of the first conveyor belt 21 and the input end of the second conveyor belt 31. It transfers the battery cells on the first conveyor belt 21 one by one to the second conveyor belt 31 of the testing station 3, completing the matching of the loading rhythm, the regularization of the battery cell spacing and the connection of the station, ensuring that the battery cells enter the testing station 3 in a uniform posture. The second conveyor belt 31 serves as the carrier of the testing station 3, driving the battery cells forward. When the photoelectric switch 32 on the side detects that the battery cell has reached the preset test position, the control system immediately triggers the second conveyor belt 31 to stop, so that the battery cell stops precisely under the battery cell OCV testing mechanism 4. After the battery cell stops, the OCV testing mechanism 4 above performs a downward pressing action, sequentially completing the removal of the tab oxide layer and the crimping of the Kelvin probe 431. The entire process of OCV parameter acquisition testing is completed. After the test, the OCV testing mechanism 4 moves upward and resets, and the second conveyor belt 31 restarts, transporting the tested battery cells to the discharge end, waiting to enter the sorting process. The discharge end of the second conveyor belt 31 is connected to the sorting conveyor table 52. The tested battery cells are directly transported to the sorting conveyor table 52 for temporary storage. The sorting conveyor table 52 has its own conveying capacity and can complete the access and delivery of battery cells. According to the battery cell grade obtained from the test, such as grade A, grade B, defective, etc., the control system drives the linear module 53 to drive the sorting conveyor table 52 to move laterally back and forth, accurately aligning it with the third conveyor belt 51 of the corresponding grade. After alignment, the sorting conveyor table 52 starts conveying, sending the battery cells into the corresponding third conveyor belt 51, flowing to the subsequent process or the corresponding material box. Then the linear module 53 drives the sorting conveyor table 52 to reset to the discharge end of the second conveyor belt 31 to receive the next battery cell. The cycle is repeated to complete the grading and sorting of batch battery cells.

[0033] Reference Figure 9 A method for OCV testing and sorting of battery cells, comprising the following steps: Step S1: The first conveyor belt 21 transports the battery cell to be tested. Then, the transfer mechanism 22 transfers the battery cells on the first conveyor belt 21 one by one to the second conveyor belt 31 of the testing station 3. The second conveyor belt 31 serves as the carrier of the testing station 3, driving the battery cells forward. When the photoelectric switch 32 on the side detects that the battery cell has reached the preset test position, the control system immediately triggers the second conveyor belt 31 to stop, so that the battery cell stops precisely under the battery cell OCV testing mechanism 4. Step S2: The output end of the linear actuator 41 extends vertically downwards, and the two sets of self-cleaning probe contact assemblies 43 descend synchronously. The closed-state moving scraper 43241 first touches the surface of the corresponding cell electrode tab. The electrode tab generates an upward supporting reaction force on the scraper. The mounting base 42 continues to descend, and the reaction force of the electrode tab pushes the floating sleeve 4322 to overcome the elastic force of the first elastic element 4323 and retract upwards along the inside of the fixed sleeve 4321. The guide pin 43221 on the floating sleeve 4322 moves along the spiral groove 4 on the inner wall of the fixed sleeve 4321. As the spiral groove 43211 rises, the guide pin 43221, constrained by the trajectory of the spiral groove 43211, rotates circumferentially. This, in turn, drives the entire floating sleeve 4322 and the scraper assembly 4324 at the lower end to retract upwards while rotating circumferentially around the sleeve axis. The moving scraper 43241, in a closed state, closely adheres to the surface of the electrode tab and performs circular rotational scraping. Through mechanical friction, the dense oxide film, dust, and oil on the surface of the electrode tab are completely removed, exposing the pure metal substrate. This eliminates contact resistance fluctuations caused by the oxide layer at the source. The floating sleeve 4322 continues to move upwards... As the upper part retracts, the internally fixed Kelvin probe 431 moves downward relative to the floating sleeve 4322. The lower end of the probe contacts the guide ramp 432411 on the inner side of the two movable scrapers 43241. As the probe continues to descend, the vertical downward pressure is decomposed into a horizontal outward component along the guide ramp 432411, gradually pushing the two movable scrapers 43241 to slide outward synchronously along the guide rod 43242, simultaneously compressing the second elastic elements 43243 on both sides. The scrapers open to both sides at a uniform speed, without rigid impact throughout the process. When the floating sleeve 4322... When 322 retracts to its limit stroke, the Kelvin probe 431 extends fully from the opening between the two moving scrapers 43241, and is precisely pressed against the center area of ​​the cleaned electrode with the set pressure. The two sets of Kelvin probes 431 conduct synchronously, forming a complete four-wire test circuit. The test system starts and, through the Kelvin test principle of separating the current circuit and the voltage sampling circuit, eliminates the interference of lead resistance and contact resistance on voltage acquisition, and completes the high-precision measurement of cell open circuit voltage OCV. It can also simultaneously complete AC internal resistance ACIR detection. Step S3: During the measurement process, the Kelvin test probe reads the original value of the open circuit voltage Vraw and the original value of the AC internal resistance Rraw of the cell. At the same time, the non-contact infrared temperature measurement component built into the equipment control system measures the actual value of the current surface temperature Tc of the cell in real time. Step S4: The main control system corrects the measured values ​​based on the actual values ​​of the battery cells collected and the preset mathematical model of battery cell temperature characteristics, and calculates the corrected voltage value V25 and the corrected internal resistance value R25 at the standard temperature of 25℃. Step S5: After the test is completed, the OCV testing mechanism 4 moves upward and resets, and the second conveyor belt 31 restarts, conveying the tested battery cells to the discharge end, waiting to enter the sorting process. The discharge end of the second conveyor belt 31 connects to the sorting conveyor table 52. The tested battery cells are directly conveyed to the sorting conveyor table 52 for temporary storage. The sorting conveyor table 52 has its own conveying capacity and can complete the input and output of battery cells. According to the battery cell grade obtained from the test, such as A grade, B grade, defective product, etc., the control system drives the linear module 53 to drive the sorting conveyor table 52 to move laterally back and forth, accurately aligning it with the corresponding grade of the third conveyor belt 51. After alignment, the sorting conveyor table 52 starts conveying, sending the battery cells into the corresponding third conveyor belt 51, flowing to the subsequent process or the corresponding material box. Then, the linear module 53 drives the sorting conveyor table 52 to reset to the discharge end of the second conveyor belt 31 to receive the next battery cell, and repeats the cycle to complete the grading and sorting of batch battery cells.

[0034] The temperature compensation correction calculation formula in step S4 is as follows: V25 = Vraw - α * (Tc - 25) R25 = Rraw * [1 - β * (Tc - 25)].

[0035] In the formula, α is the open-circuit voltage temperature coefficient of the cell at the current state of charge (SOC), in mV / ℃; β is the internal resistance temperature coefficient of the cell at the current state of charge (SOC), in / ℃; and 25 is the reference temperature.

[0036] The open-circuit voltage temperature coefficient α and the internal resistance temperature coefficient β are obtained by the following calibration method: randomly select sample cells from the same batch, set multiple temperature gradient points Ti in a controlled constant temperature chamber, and after being kept at a constant temperature at each temperature gradient point for more than a set time, measure the corresponding steady-state open-circuit voltage value VTi and steady-state internal resistance value RTi. Use the least squares method to perform linear or polynomial fitting, and calculate the slopes, which are the α and β respectively.

[0037] Multiple temperature gradient points Ti include 10℃, 20℃, 25℃, 30℃, 40℃, etc.

[0038] The temperature compensation correction in step S4 also includes: the main control system compares the actual temperature values ​​Tc of multiple adjacent cells measured by the same test position in real time. If the temperature change value ΔTc=|Tc,n-Tc,n-1| of adjacent tests exceeds 3℃, the main control system determines that there is a contact abnormality or temperature sensing blockage at the test position, sends an alarm signal, and automatically marks the measured cell as a position to be re-inspected.

[0039] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0040] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0041] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A battery cell OCV testing and sorting device, characterized in that, include: Rack (1); The feeding conveyor mechanism (2) is located on one side of the frame (1); The inspection station (3) is located at the discharge port of the feeding conveyor (2); The cell OCV testing mechanism (4) is set above the testing station (3), including a linear driver (41) with its output end vertically downward set above the testing station (3). The output end of the linear driver (41) is provided with a mounting base (42), and the mounting base (42) is provided with self-cleaning probe contact components (43) on opposite sides. The feeding and sorting mechanism (5) is connected to the discharge port of the testing station (3) for sorting the battery cells; The self-cleaning probe assembly includes a Kelvin probe (431) and a self-cleaning component (432) for scraping off the oxide layer on the surface of the battery cell tab before the Kelvin probe (431) contacts the battery cell tab.

2. The cell OCV testing and sorting equipment according to claim 1, characterized in that, The self-cleaning component (432) includes: A fixed sleeve (4321) is provided on the mounting base (42) and has a Kelvin probe (431) inside. A floating sleeve (4322) and a first elastic element (4323) are provided. The floating sleeve (4322) is coaxially and telescopically disposed in a fixed sleeve (4321) through the first elastic element (4323). A spiral groove (43211) is provided in the fixed sleeve (4321). A guide pin (43221) adapted to the spiral groove (43211) is provided on the floating sleeve (4322). The scraper assembly (4324) is located at the lower end of the floating sleeve (4322).

3. The cell OCV testing and sorting equipment according to claim 2, characterized in that, The scraper assembly (4324) includes: The movable scraper (43241) has mounting grooves (43222) on both sides of the lower opening of the floating sleeve (4322). The movable scraper (43241) is provided on both sides of the mounting groove (43222) in a reciprocating manner. Guide rod (43242), each movable scraper (43241) is provided with a guide rod (43242) passing through each mounting slot (43222); The second elastic element (43243) is respectively sleeved on both sides of each guide rod (43242). One end of the second elastic element (43243) abuts or is fixed to the movable scraper (43241), and the other end abuts or is fixed to the inner wall of the mounting groove (43222).

4. The cell OCV testing and sorting equipment according to claim 3, characterized in that, Each movable scraper (43241) has a guide ramp (432411) inclined on its upper side.

5. The cell OCV testing and sorting equipment according to claim 1, characterized in that, The feeding and conveying mechanism (2) includes: The first conveyor belt (21) is located on one side of the frame (1); A transfer mechanism (22) is located at the output end of the first conveyor belt (21); The testing station (3) includes: The second conveyor belt (31) is located at the output end of the transfer mechanism (22); A photoelectric switch (32) is disposed on one side of the second conveyor belt (31); The material sorting mechanism (5) includes: The third conveyor belt (51) is arranged in parallel on one side of the second conveyor belt (31); The sorting conveyor (52) and the linear module (53) are arranged on one side of the second conveyor belt (31) and the third conveyor belt (51) via the linear module (53).

6. A cell OCV testing and sorting method based on the device according to any one of claims 1-5, characterized in that, Includes the following steps: Step S1: The first conveyor belt (21) transports the battery cell to be tested, and then the transfer mechanism (22) transfers the battery cell on the first conveyor belt (21) one by one to the second conveyor belt (31) of the testing station (3). The second conveyor belt (31) serves as the carrier of the testing station (3) and drives the battery cell forward. When the photoelectric switch (32) on the side detects that the battery cell has reached the preset test position, the control system immediately triggers the second conveyor belt (31) to stop, so that the battery cell stops precisely under the battery cell OCV testing mechanism (4). Step S2: The output end of the linear actuator (41) extends vertically downwards, and the two sets of self-cleaning probe contact components (43) descend synchronously. The closed-state moving scraper (43241) first touches the surface of the corresponding cell electrode tab. The electrode tab generates an upward supporting reaction force on the scraper. The mounting base (42) continues to descend, and the reaction force of the electrode tab pushes the floating sleeve (4322) to overcome the elastic force of the first elastic element (4323) and retract upwards along the inside of the fixed sleeve (4321). The guide pin (43221) on the floating sleeve (4322) moves along the inner wall of the fixed sleeve (4321). The spiral groove (43211) climbs upward, and the trajectory of the spiral groove (43211) constrains the guide pin (43221) to generate circumferential rotation, which in turn drives the entire floating sleeve (4322) and the scraper assembly (4324) at the lower end to retract upward while rotating circumferentially around the sleeve axis. The moving scraper (43241) in the closed state closely adheres to the surface of the electrode tab and performs circular rotation scraping. Through mechanical friction, the dense oxide film, dust and oil on the surface of the electrode tab are completely removed, exposing the pure metal substrate. This eliminates the contact resistance fluctuations caused by the oxide layer from the root. The floating sleeve (43211) 2) As the probe continues to retract upwards, the internally fixed Kelvin probe (431) moves downwards relative to the floating sleeve (4322). The lower end of the probe contacts the guide ramp (432411) on the inner side of the two movable scrapers (43241). As the probe continues to descend, the vertical downward pressure is decomposed into a horizontal outward component along the guide ramp (432411), gradually pushing the two movable scrapers (43241) to slide outwards synchronously along the guide rod (43242), simultaneously compressing the second elastic elements (43243) on both sides. The scrapers open to both sides at a uniform speed, with no rigid impact throughout the process. When the floating sleeve (4322) retracts to its limit stroke, the Kelvin probe (431) extends fully from the opening between the two moving scrapers (43241) and presses precisely onto the center area of ​​the cleaned electrode with the set pressure. The two sets of Kelvin probes (431) are synchronously connected to form a complete four-wire test circuit. The test system is started. By using the Kelvin test principle that separates the current circuit and the voltage sampling circuit, the interference of lead resistance and contact resistance on voltage acquisition is eliminated, and the high-precision measurement of cell open circuit voltage OCV is completed. The AC internal resistance ACIR detection can also be completed simultaneously. Step S3: During the measurement process, the Kelvin test probe reads the original value of the open circuit voltage Vraw and the original value of the AC internal resistance Rraw of the cell. At the same time, the non-contact infrared temperature measurement component built into the equipment control system measures the actual value of the current surface temperature Tc of the cell in real time. Step S4: The main control system corrects the measured values ​​based on the actual values ​​of the battery cells collected and the preset mathematical model of battery cell temperature characteristics, and calculates the corrected voltage value V25 and the corrected internal resistance value R25 at the standard temperature of 25℃. Step S5: After the test is completed, the OCV testing mechanism (4) moves upward and resets, and the second conveyor belt (31) restarts, transporting the tested battery cells to the discharge end, waiting to enter the sorting process. The discharge end of the second conveyor belt (31) connects to the sorting conveyor table (52). The tested battery cells are directly transported to the sorting conveyor table (52) for temporary storage. The sorting conveyor table (52) itself has conveying capacity and can complete the access and delivery of battery cells. The control system determines the battery cell grade based on the test results, such as Grade A, Grade B, etc. Defective products, etc., drive the linear module (53) to drive the sorting conveyor (52) to move back and forth laterally, accurately aligning with the third conveyor belt (51) of the corresponding gear. After alignment, the sorting conveyor (52) starts conveying, sending the battery cell into the corresponding third conveyor belt (51), flowing to the subsequent process or the corresponding material box. Then the linear module (53) drives the sorting conveyor (52) to reset to the discharge end of the second conveyor belt (31) to receive the next battery cell, and repeats the cycle to complete the grading and sorting of batch battery cells.

7. The cell OCV testing and sorting method according to claim 6, characterized in that, The temperature compensation correction calculation formula in step S4 is as follows: V25 = Vraw - α * (Tc - 25) R25 = Rraw * [1 - β * (Tc - 25)].

8. The cell OCV testing and sorting method according to claim 7, characterized in that, The open-circuit voltage temperature coefficient α and the internal resistance temperature coefficient β are obtained through the following calibration method: Randomly select sample cells from the same batch and set multiple temperature gradient points Ti in a controlled constant temperature chamber. After being kept at a constant temperature for more than a set time at each temperature gradient point, measure the corresponding steady-state open-circuit voltage V(Ti) and steady-state internal resistance R(Ti). Use the least squares method to perform linear or polynomial fitting and calculate the slopes, which are α and β respectively.

9. The cell OCV testing and sorting method according to claim 6, characterized in that, The temperature compensation correction in step S4 also includes: The main control system compares the actual temperature values ​​Tc of multiple adjacent cells measured at the same test position in real time. If the temperature change value ΔTc=|Tc,n-Tc,n-1| of adjacent tests exceeds 3℃, the main control system determines that there is a contact abnormality or temperature sensing obstruction at the test position, sends an alarm signal, and automatically marks the measured cell as a position to be re-inspected.

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