Method and equipment for large-scale detection of infiltration uniformity of lithium ion battery

Abstract

The invention relates to a method and equipment for large-scale detection of infiltration uniformity and consistency of lithium ion batteries, belongs to the technical field of battery manufacturing and detection, and aims to solve the problems of high destructiveness, low efficiency and incapability of real-time judgment in an existing infiltration consistency detection mode. According to the method, linear voltage scanning is applied to the battery through the test unit, response current is collected, the Cd value of the differential capacitance of the double electric layers of the battery is calculated in combination with the control unit and the data storage and analysis unit, and the infiltration state of the battery is judged based on Cd value distribution. The equipment has a multi-channel parallel detection capability, can realize rapid, lossless and efficient infiltration consistency evaluation, and improves the safety and consistency of the battery manufacturing process.

Description

Technical Field

[0001] The invention belongs to the technical field of battery manufacturing detection, and relates to a method and equipment for large-scale detection of the uniformity of infiltration of lithium-ion batteries. Background Art

[0002] Lithium-ion batteries, currently the mainstream energy storage device, are widely used in consumer electronics, electric vehicles, and energy storage systems. To ensure stable battery performance and safety, battery consistency control is crucial throughout the entire production process. In particular, after cell assembly and electrolyte injection, the battery requires a period of rest to allow the electrolyte to fully penetrate the electrode and separator, forming a stable solid-liquid interface that provides a foundation for subsequent formation and activation processes.

[0003] Currently, the industry generally adopts a method of extending the rest time to ensure sufficient battery impregnation. However, this method not only has a long cycle time, but also increases the number of work-in-progress on the production line, significantly affecting the tact and efficiency of battery production. Moreover, during large-scale production, the degree of impregnation between different battery cells may still vary due to factors such as materials, process parameters, or environmental differences, further increasing the difficulty of controlling the consistency of the finished product.

[0004] Some existing technologies attempt to assist in determining the degree of infiltration by disassembling the battery or introducing markers. For example, existing solutions add a colored wetting agent to the electrolyte and observe the color change of the electrode to assess the infiltration level. However, such methods often rely on manual visual inspection, which is highly subjective and requires battery disassembly. This leads to low testing efficiency, high destructiveness, and difficulty in industrialization.

[0005] There are also technologies that indirectly reflect the infiltration situation by analyzing the electrochemical characteristic signals of the battery during the formation and charging process. For example, patent CN113991198A proposes monitoring the peak intensity of the film-forming potential of ethylene carbonate, a film-forming additive, to infer the distribution of the electrolyte. Figure 1 However, these methods require the battery to be formed before they can be judged, which has a lag effect and is not conducive to real-time monitoring and control of the production process. Furthermore, the relevant testing equipment is usually expensive and the testing time is long, making it unsuitable for online rapid screening.

[0006] Therefore, there is an urgent need for a non-destructive, rapid, and parallel detection method and supporting equipment to determine the wetting uniformity of lithium-ion batteries after the injection process, help factories accurately control the wetting time, improve production efficiency, and reduce defects such as black spots and lithium plating caused by insufficient wetting, as well as the subsequent safety risks.

[0007] In recent years, with the development of electrochemical detection technology, the changing trend of double-layer differential capacitance has become an important indicator to characterize the degree of contact between the electrolyte and the electrode. The double-layer differential capacitance is determined by the charge layer structure formed between the surface of the electrode material and the electrolyte. This parameter has good response characteristics to the battery infiltration process. Based on this characteristic, the proposed detection method based on double-layer differential capacitance has potential advantages and can provide technical support for the rapid quantitative evaluation of lithium-ion battery infiltration consistency. This method can be used for detection before the battery is formed, and has the advantages of being fast, non-destructive, and highly efficient. It is particularly suitable for online quality control of large-scale production lines. Summary of the Invention

[0008] In view of this, an object of the present invention is to provide a method and apparatus for large-scale detection of the uniformity of infiltration of lithium-ion batteries.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A method for detecting the uniformity of lithium-ion battery infiltration comprises the following steps:

[0011] S1: Provide testing equipment with control unit, data storage and analysis unit, test unit and multi-channel connection function;

[0012] S2: After the lithium-ion battery to be tested has completed the slurry coating, roller pressing, electrode sheet cutting, electrode core forming, packaging, baking and liquid injection processes, it is placed on the testing equipment;

[0013] S3: Connecting multiple lithium-ion batteries to the test unit through the multi-channel connection function;

[0014] S4: At different immersion time points, control the test unit to apply a cyclic linear voltage sweep test at a certain scan rate to the battery, monitor its response current, and avoid the occurrence of redox peaks in the voltage range;

[0015] S5: The data storage analysis unit performs the following steps according to the formula

[0016]

[0017] Among them, C d is the double layer differential capacitance, i is the response current, dV / dt is the scan rate,

[0018] Calculate the C of the battery at each time point d value, and record the C value of all test batteries d value;

[0019] S6: Analyze the C d The distribution of values, if the C dIf the value deviates significantly from the batch average, the battery is judged to be insufficiently impregnated and the impregnation process continues; the remaining batteries enter the subsequent process;

[0020] S7: Repeat steps S4 to S6 for the battery that is not fully wetted until its C d The value meets the distribution consistency requirement.

[0021] Furthermore, the starting voltage of the voltage scan is the open circuit voltage of the battery ±0.1V.

[0022] Furthermore, the C d The distribution consistency of values ​​is judged based on statistical analysis to determine whether there are outliers.

[0023] Furthermore, the C d When the value reaches a stable value, the battery is considered to be fully soaked.

[0024] A device for detecting the uniformity of lithium-ion battery infiltration, comprising:

[0025] A test unit, used for applying a linear sweep voltage to the lithium-ion battery and collecting a response current;

[0026] A control unit, used to control the scanning voltage and scanning rate;

[0027] The data storage and analysis unit is used to receive the response current data of the test unit and calculate the double-layer differential capacitance C d value and determine its distribution;

[0028] The multi-channel connection module is used to connect multiple lithium-ion batteries to the test unit at the same time to achieve parallel testing.

[0029] Furthermore, the multi-channel connection module ensures that the test channels are independent of each other and the contact resistance is less than 0.1 milliohm.

[0030] Furthermore, the data storage and analysis unit is used to calculate the data according to the response current and the scan rate according to the formula Calculate the C d value.

[0031] Furthermore, the test unit has a function of dynamically adjusting the voltage interval to avoid redox peaks during the test process.

[0032] Furthermore, the data storage and analysis unit is used to record C at different infiltration time points. d value, and judge whether the battery is fully soaked based on its changing trend over time.

[0033] Furthermore, the control unit is provided with a user interface for setting voltage scanning parameters and infiltration detection strategies.

[0034] The beneficial effects of the present invention are:

[0035] First, the present invention can realize non-destructive detection of the battery infiltration process, avoiding destructive operations such as disassembling the battery or introducing color marking in the prior art, and ensuring the integrity and practicality of the battery.

[0036] Secondly, the present invention can quickly determine whether the battery has reached the infiltration completion state by collecting and analyzing the electrochemical response signal of the battery in real time, thereby effectively shortening unnecessary standing time and improving production efficiency.

[0037] Thirdly, the present invention adopts a detection method based on double-layer differential capacitance, which avoids the subjective errors caused by relying on human judgment and improves the accuracy and reliability of detection.

[0038] In addition, the present invention is equipped with a multi-channel testing system that can perform parallel testing on multiple batteries at the same time, adapting to large-scale production needs, improving testing throughput and supporting flexible production scheduling.

[0039] Furthermore, by analyzing the distribution pattern of the double-layer differential capacitance between batteries, the present invention can identify individual batteries with insufficient wetting, achieve consistency screening within batches, avoid subsequent safety hazards caused by wetting differences, and help reduce the probability of quality problems such as interface black spots and lithium plating.

[0040] Finally, the present invention constructs a complete intelligent detection architecture by combining a control unit, a data analysis unit and a multi-channel system, which not only improves the judgment accuracy, but also provides a basis for subsequent automated decision-making, helping the production line achieve efficient and controllable quality management goals.

[0041] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0043] Figure 1 The results of infiltration analysis for patent CN113991198A;

[0044] Figure 2 Schematic diagram of the equipment operation;

[0045] Figure 3For the distribution of insufficiently wetted cells;

[0046] Figure 4 C during battery immersion d the law of change;

[0047] Figure 5 It is the detection logic for the uniformity of battery wetting in batches. DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0049] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0050] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0051] The present invention proposes a device that detects the differential capacitance of the double electric layer during the battery infiltration process, thereby verifying the consistency of battery infiltration between batches and reducing the subsequent black spots / lithium deposition and safety risks caused by inconsistent infiltration.

[0052] During the infiltration process, the electrolyte enters the interior of the electrode through the gap between the electrode and the diaphragm by capillary action and reaches the surface of the active material. When the electrolyte is distributed on the surface of all active materials, the infiltration is completed. From a microscopic point of view, when the active material and the electrolyte come into contact, a solid-liquid interface is formed, and a double-layer structure is formed at the solid-liquid interface. Charge accumulation or loss will appear on the solid phase surface: and the liquid phase will be attracted to the solid-liquid interface by the corresponding charged ions by electrostatic attraction. As the infiltration proceeds, the solid-liquid interface phase formed gradually increases. When the infiltration reaches the end point, the solid-liquid interface reaches its maximum value, and the double layer formed also reaches its maximum value. The double-layer structure also has the ability to store charge, namely the double-layer differential capacitance C d That is, when the battery's C d When the value reaches the maximum, the infiltration is completed and the subsequent process can be carried out.

[0053] In the mass production process, the capacity of the same batch of batteries remains unchanged, that is, the total amount of active substances inside them maintains a stable distribution. At this time, the C d will also remain in the same distribution range when the C between batch classes / d The value is outlier, such as Figure 3 As shown, it means that the battery is not fully wetted and cannot enter the subsequent process. It should be tested and qualified before it can be circulated.

[0054] To test the double-layer differential capacitance of the battery, after injecting the electrolyte, the battery is subjected to a cyclic linear voltage test at a certain scan rate in a fixed voltage range through the test unit. The scan rate of the test is variable, and the response current after stabilization is monitored. When a redox peak appears in the voltage range, the voltage range should be narrowed until the peak disappears. The starting voltage is selected at the open circuit voltage of the battery ±0.1V.

[0055] Battery C d The calculation can be calculated according to the following formula:

[0056]

[0057] Among them, i is the response current, dV / dt is the scanning rate, which can be monitored and calculated in real time by the analysis and calculation unit and then recorded and saved in the storage unit.

[0058] By testing the cell at regular intervals, as the soaking progresses, the C d The value gradually increases, such as Figure 4 As shown, it then reaches a stable state. d The value is the punctuation point where the battery is soaked. In order to ensure the difference of battery batch soaking, the C value of the battery batch can be measured. d When the distribution of values ​​is uniform and there is no outlier, there is no difference in infiltration between batches and the batches can proceed to the subsequent process.

[0059] At the same time, multi-channel testing ensures the number of tests and can run independently of each other. The contact resistance between the battery and the test channel should be less than 0.1 milliohms.

[0060] The core of the present invention is to propose a device for detecting the consistency of lithium-ion battery infiltration, which includes a test unit, a control unit, a data storage and analysis unit and a multi-channel system. d The values ​​were tested and then the C d The distribution pattern is used to determine whether the infiltration is consistent, thereby achieving rapid and comprehensive screening, accelerating production rhythm, improving production efficiency, and reducing interface / lithium plating and safety risks caused by poor infiltration.

[0061] The above-described part is the core part of the device. Without making any functional changes, the relevant functions can be achieved by disassembling and combining the above-mentioned parts, which is also within the protection scope of the present invention. In addition, the above embodiments only illustrate the implementation process of this application, and the description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the patent of this application. For ordinary technicians in this field, several variations and improvements can be made without departing from the concept of this application, which all fall within the scope of protection of this application. Therefore, the scope of protection of this application shall be based on the attached claims, such as Figure 5 shown.

[0062] Example 1: Batch Wetting Consistency Screening Process for Battery Production Lines

[0063] This embodiment provides a wetting consistency detection method for lithium-ion battery large-scale production lines, which is mainly used to screen the wetting status of batteries in the same batch and determine whether they can enter the subsequent formation process.

[0064] The specific process is as follows:

[0065] The lithium-ion batteries that have completed the injection process are numbered and registered, classified into batches, and placed in the multi-channel interface of the testing equipment, with each channel connected to a battery.

[0066] Start the control unit, set the voltage scan starting voltage to 0.1 volt above and below the battery open circuit voltage, set the initial scan rate, and start the test unit to perform a linear scan.

[0067] The response current curve of each battery during the scanning process is collected, and the double-layer differential capacitance Cd value is calculated in real time by the data analysis unit.

[0068] All cells were immersed at the same time point C d The values ​​are recorded uniformly, and the analysis module is used to analyze the battery C dThe distribution statistics of the values ​​are performed to identify whether there are outlier samples that deviate from the mean.

[0069] If some batteries C d If the value is significantly lower than the median of the distribution, it is judged as insufficient infiltration and the batteries are screened out and returned to continue standing; the remaining batteries enter the subsequent formation process.

[0070] For batteries that are not fully soaked, repeat the above steps after standing for a certain period of time until their C d The values ​​satisfy the distribution consistency criterion.

[0071] This process enables rapid and non-destructive consistency assessment of an entire batch of batteries, significantly improving testing efficiency and quality control levels.

[0072] Example: Multi-channel parallel detection and automatic screening system integration process

[0073] This embodiment is aimed at automated production scenarios, combining a multi-channel testing system with a screening module to achieve high-throughput detection and automatic sorting.

[0074] The specific process is as follows:

[0075] After the batch batteries are filled, they are transported to the automatic inspection station via a transmission line, and the robotic arm automatically connects the batteries to the test channel.

[0076] The control unit synchronously triggers all test channels to perform voltage scans. Test parameters include voltage range and scan rate presets.

[0077] The test unit obtains the response current in parallel, and the analysis unit performs C on each channel of data. d Calculation, all data transmitted to the central data system.

[0078] Data system completed C d Statistical distribution analysis, automatic identification of C d The batteries with abnormal values ​​are numbered and their channel locations are marked.

[0079] After the test, the robotic arm automatically places qualified batteries into the qualified area, and unqualified batteries are sent to the re-immersion area or for secondary testing.

[0080] The system can repeat the inspection process according to the set time period and generate batch inspection reports for tracking process quality.

[0081] This process realizes intelligent identification, automatic sorting and data management of battery infiltration status, and is suitable for quality control in large-scale continuous production lines.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for detecting the uniformity of infiltration of lithium-ion batteries, characterized by: The steps include: S1: Provide testing equipment with control unit, data storage and analysis unit, test unit and multi-channel connection function; S2: After the lithium-ion battery to be tested has completed the slurry coating, roller pressing, electrode sheet cutting, electrode core forming, packaging, baking and liquid injection processes, it is placed on the testing equipment; S3: Connecting multiple lithium-ion batteries to the test unit through the multi-channel connection function; S4: At different immersion time points, control the test unit to apply a cyclic linear voltage sweep test at a certain scan rate to the battery, monitor its response current, and avoid the occurrence of redox peaks in the voltage range; S5: The data storage analysis unit performs the following steps according to the formula Among them, C d is the double layer differential capacitance, i is the response current, dV / dt is the scan rate, Calculate the C of the battery at each time point d value, and record the C value of all test batteries d value; S6: Analyze the C d The distribution of values, if the C d If the value deviates significantly from the batch average, the battery is judged to be insufficiently impregnated and the impregnation process continues; the remaining batteries enter the subsequent process; S7: Repeat steps S4 to S6 for the battery that is not fully wetted until its C d The value meets the distribution consistency requirement.

2. The method for detecting the uniformity of infiltration of a lithium-ion battery according to claim 1, wherein: The starting voltage of the voltage scan is the open circuit voltage of the battery ±0.1V.

3. The method for detecting the uniformity of infiltration of a lithium-ion battery according to claim 1, wherein: The C d The distribution consistency of values ​​is judged based on statistical analysis to determine whether there are outliers.

4. The method for detecting the uniformity of the infiltration of a lithium-ion battery according to claim 1, wherein: The C d When the value reaches a stable value, the battery is considered to be fully soaked.

5. A device for detecting the uniformity of lithium-ion battery infiltration, characterized by: include: A test unit, used for applying a linear sweep voltage to the lithium-ion battery and collecting a response current; A control unit, used to control the scanning voltage and scanning rate; The data storage and analysis unit is used to receive the response current data of the test unit and calculate the double-layer differential capacitance C d value and determine its distribution; The multi-channel connection module is used to connect multiple lithium-ion batteries to the test unit at the same time to achieve parallel testing.

6. The device for detecting the uniformity of the infiltration of lithium-ion batteries according to claim 5, characterized in that: The multi-channel connection module ensures that the test channels are independent of each other and the contact resistance is less than 0.1 milliohm.

7. The device for detecting the uniformity of lithium-ion battery infiltration according to claim 5, characterized in that: The data storage analysis unit is used to calculate the response current and the scan rate according to the formula Calculate the C d value.

8. The device for detecting the uniformity of the infiltration of lithium-ion batteries according to claim 5, characterized in that: The test unit has a function of dynamically adjusting the voltage interval to avoid redox peaks during the test process.

9. The device for detecting the uniformity of the infiltration of lithium-ion batteries according to claim 5, characterized in that: The data storage and analysis unit is used to record C at different infiltration time points d value, and judge whether the battery is fully soaked based on its changing trend over time.

10. The device for detecting the uniformity of lithium-ion battery infiltration according to claim 5, characterized in that: The control unit is provided with a user interface for setting voltage scanning parameters and infiltration detection strategy.

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