Battery inspection apparatus, flat panel detector, and battery production device

Abstract

A battery inspection apparatus (400), a flat panel detector (430), and a battery production device. The battery inspection apparatus (400) comprises a bearing assembly (410), a ray source (420), and a flat panel detector (430); the bearing assembly (410) is used for bearing a battery under test (100), the ray source (420) is located at one end of the bearing assembly (410), and the direction in which a detection ray of the ray source (420) is emitted faces the battery under test (100); the flat panel detector (430) is located at the other end of the bearing assembly (410) distant from the ray source (420), the flat panel detector (430) is used for receiving a detection ray that is emitted by the ray source (420) and penetrates through the battery under test (100), the flat panel detector (430) comprises a scintillator layer (431), and the thickness of the scintillator layer (431) is greater than a first preset thickness, so that the density resolution of the flat panel detector (430) is less than 0.5%.

Description

Battery testing device, flat panel detector and battery production equipment

[0001] Cross-references

[0002] This application refers to Chinese patent application No. 202321708514.3, filed on June 30, 2023, entitled “Battery Detection Device, Flat Panel Detector and Battery Production Equipment”, which is incorporated into this application in its entirety by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery detection device, a flat panel detector, and battery production equipment. Background Art

[0004] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0005] As major automakers and user groups place increasing emphasis on the safety of electric vehicles, battery manufacturers are improving battery production efficiency while also implementing stricter and more comprehensive controls on defective batteries that may be produced during the manufacturing process. Batteries can develop various internal defects during the production process, which can affect their quality and safety. Currently, internal defect detection for batteries is typically performed through manual observation of their appearance, which can be inaccurate. Furthermore, with the increasing number of battery usage scenarios, larger battery sizes have become a key trend in future battery development, placing higher demands on the detection of internal defects.

[0006] Summary of the Invention

[0007] The present application aims to solve at least one of the technical problems in the background art. To this end, one object of the present application is to provide a battery detection device, a flat panel detector, and a battery production equipment to improve the accuracy of detecting internal defects in batteries.

[0008] An embodiment of the first aspect of the present application provides a battery detection device, which includes a carrying assembly, a radiation source and a flat-panel detector; the carrying assembly is used to carry a battery to be tested, the radiation source is located at one end of the carrying assembly, and the detection radiation of the radiation source is emitted in a direction toward the battery to be tested; the flat-panel detector is located at the other end of the carrying assembly away from the radiation source, and the flat-panel detector is used to receive the detection radiation emitted by the radiation source and penetrating the battery to be tested, and the flat-panel detector includes a scintillator layer, and the thickness of the scintillator layer is greater than a first preset thickness so that the density resolution of the flat-panel detector is less than 0.5%.

[0009] According to the embodiments of the present application, by adjusting the thickness of the scintillator layer of the flat-panel detector so that the density resolution of the flat-panel detector is less than 0.5%, the detection capability of the battery detection device is improved, and it is compatible with the density resolution requirements of thicker batteries to be tested, which is beneficial to improving the accuracy of the detection results of the batteries to be tested, and can realize the detection of batteries to be tested of various specifications, while taking into account the economy of battery detection.

[0010] In some embodiments, the thickness of the scintillator layer is less than a second predetermined thickness, such that a ratio α of the contrast ratio of the output image to the input image of the flat-panel detector satisfies the following: 50% ≤ α < 1. Properly selecting the thickness of the scintillator layer allows the flat-panel detector to achieve both density resolution and spatial resolution, thereby better accommodating internal inspection of thicker batteries under test, improving the quality of the inspection image, and thereby increasing the accuracy of defect detection in the batteries under test.

[0011] In some embodiments, the quantum detection efficiency λ of the flat-panel detector satisfies the following condition: 0.5 ≤ λ < 1. By limiting the quantum detection efficiency of the flat-panel detector, the sensitivity and density resolution of the flat-panel detector can be guaranteed to a certain extent, thereby improving the imaging quality of the image, thereby helping to improve the accuracy of the detection image recognition and the accuracy of the battery detection results.

[0012] In some embodiments, the thickness t of the scintillator layer satisfies the following: 400 microns < t < 1000 microns. By properly selecting the thickness range of the scintillator layer in the flat panel detector, the density resolution and spatial resolution of the flat panel detector are balanced, thereby being able to adapt to objects of varying sizes and expanding its applicability.

[0013] In some embodiments, the thickness t of the scintillator layer satisfies the following: 600 microns ≤ t ≤ 700 microns. By further selecting an appropriate scintillator layer thickness, while meeting the detection requirements for the size of the object being tested, while more reasonably balancing the requirements for density resolution and spatial resolution, the detection performance of the flat-panel detector is improved, thereby meeting the quality requirements for detection images of batteries with a wider range of thicknesses, thereby helping to improve the accuracy of image recognition and detection results.

[0014] In some embodiments, the density resolution β of the flat panel detector satisfies the following condition: 0 < β ≤ 0.38%. By further limiting the range of density resolution of the flat panel detector, the flat panel detector's detection capability can be better matched to the thickness of the object to be tested, thereby increasing the size range of batteries to be tested that the flat panel detector is compatible with, reducing the time required for equipment replacement due to insufficient detection accuracy, and improving detection efficiency.

[0015] In some embodiments, the radiation source is an integrated radiation source, the scintillator layer includes cesium iodide, and the photoelectric conversion layer includes amorphous silicon thin-film transistors. A flat-panel detector with this cesium iodide and thin-film transistor structure exhibits low photon loss, resulting in a relatively high quantum detection efficiency, thereby improving the detection efficiency of the flat-panel detector.

[0016] In some embodiments, the rated voltage V of the radiation source satisfies the following conditions: 130 kV ≤ V ≤ 150 kV, and / or the rated current I of the radiation source satisfies the following conditions: 300 μA ≤ I ≤ 500 μA. By limiting the type of radiation tube, the rated voltage V, and the rated current I, it is possible to provide a satisfactory detection radiation dose while also ensuring the stability and reliability of the radiation source. Furthermore, the radiation source and the flat-panel detector can be coordinated to meet the detection accuracy requirements for batteries with a wider range of thicknesses, thereby improving detection efficiency and accuracy.

[0017] In some embodiments, the maximum size d of the focus of the radiation source satisfies: 0<d≤80 microns. Specific limitation of the focus size can better match the detection accuracy of the battery detection device with the size of the battery to be tested, thereby improving detection accuracy and efficiency.

[0018] In some embodiments, the battery testing device further includes a processor connected to the flat-panel detector and configured to receive electrical signals from the flat-panel detector and output test results for the battery under test. By configuring the processor to receive image signals generated by the flat-panel detector, identify the detected image, and output the test results for the battery under test, automatic detection of internal defects in the battery under test can be achieved, thereby improving the automation and efficiency of the battery testing device.

[0019] An embodiment of a second aspect of the present application provides a flat-panel detector for inspecting batteries under test. The flat-panel detector includes a scintillator layer and a photoelectric conversion layer stacked along a thickness direction. The scintillator layer is configured to receive detection radiation and emit visible light. The photoelectric conversion layer receives the visible light emitted by the scintillator layer and generates a corresponding electrical signal. The thickness of the scintillator layer is greater than a first predetermined thickness, such that the density resolution of the flat-panel detector is less than 0.5%. The flat-panel detector of this embodiment can further improve the density resolution under a constant radiation dose, thereby meeting the inspection requirements of batteries under test over a wide range of sizes, improving image quality, and thereby increasing the accuracy of internal defect detection in the batteries under test.

[0020] In some embodiments, the thickness of the scintillator layer is less than a second predetermined thickness such that a ratio α of the contrast ratio of the output image to the input image of the flat-panel detector satisfies the following: 50% ≤ α < 1. Further limiting the thickness of the scintillator layer so that the spatial resolution of the flat-panel detector meets predetermined requirements allows the flat-panel detector to achieve both density resolution and spatial resolution, thereby improving image quality.

[0021] In some embodiments, the thickness t of the scintillator layer satisfies the following conditions: 600 μm ≤ t ≤ 700 μm, the quantum detection efficiency λ of the flat-panel detector satisfies the following conditions: 0.5 ≤ λ < 1, and the density resolution β of the flat-panel detector satisfies the following conditions: 0 < β ≤ 0.38%. By selecting an appropriate scintillator layer thickness, the flat-panel detector can achieve a more balanced quantum detection efficiency, density resolution, and spatial resolution, thereby meeting the detection accuracy requirements for thicker batteries under test and expanding the applicability of the flat-panel detector.

[0022] An embodiment of the third aspect of the present application provides a battery production device, including the battery detection device in the above embodiment.

[0023] An embodiment of the fourth aspect of the present application provides a battery testing method, using the above-mentioned battery testing device, the method comprising: transferring the battery to be tested to a testing station; obtaining a test image of the battery to be tested; and identifying the test image to determine whether the battery to be tested has defects.

[0024] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0026] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application;

[0027] FIG2 is a schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0028] FIG3 is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0029] FIG4 is a schematic structural diagram of a battery detection device according to some embodiments of the present application;

[0030] FIG5 is a schematic diagram of the structure of a flat panel detector according to some embodiments of the present application;

[0031] FIG6 is a flow chart of a detection method of a battery detection device according to some embodiments of the present application;

[0032] FIG7 is a schematic diagram of a detection image of a battery under test according to some embodiments of the present application;

[0033] FIG8 is a schematic diagram of detection images of batteries to be tested according to other embodiments of the present application;

[0034] FIG9 is a schematic diagram of detection images of batteries to be tested according to some other embodiments of the present application.

[0035] Explanation of the accompanying drawings: Vehicle 1000; Battery 100, Controller 200, Motor 300; Housing 10, First Part 11, Second Part 12; Battery Cell 20, End Cap 21, Electrode Terminal 21a, Housing 22, Cell Assembly 23, Tab 23a; Battery Testing Device 400, Carrying Assembly 410, Battery to be Tested 411, Radiation Source 420, Detection Radiation 421, Flat Panel Detector 430, Scintillator Layer 431, Photoelectric Conversion Layer 432, Processor 440. DETAILED DESCRIPTION

[0036] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0038] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0039] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0041] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0042] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0043] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0044] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0045] The position and state of the electrodes within a battery cell have a significant impact on the battery's performance and safety. Taking lithium-ion batteries as an example, the internal spacing between the cathode and cathode electrodes and the amount of misalignment between the cathode and cathode electrodes are important factors affecting the safety performance of wound cells. Regarding the spacing between the cathode and cathode electrodes: During the charge and discharge process of a lithium battery, when the spacing between the cathode and cathode electrodes is large, lithium ions cannot fully embed into the anode channel, resulting in the accumulation of some lithium ions and lithium plating, which poses a significant safety risk. Therefore, the spacing between the cathode and cathode electrodes within the battery should not be too large. Regarding the misalignment between the cathode and cathode electrodes: During the charge and discharge process of a lithium battery, lithium ions repeatedly embed and deintercalate between the cathode and cathode electrodes. However, when lithium ions are released from the cathode but do not have sufficient anode channels to embed, lithium ions can easily accumulate and plating, posing a certain product safety risk. Therefore, it is necessary to ensure that the entire cathode electrode is within the coverage of the anode, that is, to ensure that the anode exceeds the cathode, that is, the misalignment between the cathode and cathode electrodes is greater than 0. Therefore, it is necessary to detect the internal spacing between the batteries and the misalignment between the cathode and cathode electrodes to promptly detect internal battery defects and reduce the outflow of defective batteries.

[0046] In order to improve the accuracy of internal defect detection of batteries, a CCD camera can be used to take pictures circle by circle to detect the misalignment between the anode and cathode. However, the electrodes are easily out of focus and difficult to identify at the winding and rewinding points. In addition, this method cannot detect the misalignment of the anode and cathode electrodes after the wound battery cell has undergone cold pressing and hot pressing processes, nor can it detect the distance between the anode and cathode electrodes.

[0047] Based on the above considerations, to address the issue of insufficient accuracy in battery internal defect detection, a ray projection detection method can be used to achieve non-destructive detection of the battery interior. By placing the battery between a ray source and a detector, the rays emitted by the ray source penetrate the battery in a direction perpendicular to the winding axis of the battery electrode and are received by the detector. This method obtains the position and status information of the cathode and anode electrodes inside the battery, thereby detecting various defects within the battery.

[0048] When the rays penetrate the corners of the battery, the closer to the inner circle the cathode and anode, the smaller the characteristic difference. As the battery cells become larger and the thickness of the battery increases, the characteristic difference of the cathode and anode in the inner circle decreases exponentially, which poses a great challenge to the detection of the misalignment of the cathode and anode in the corner area and the distance between the cathode and anode. In order to solve the problem of insufficient detection accuracy due to the excessive thickness of the battery cells, the thickness of the scintillator layer of the flat-panel detector can be optimized and the thickness of the scintillator layer can be set to be greater than the first preset thickness so that the density resolution of the flat-panel detector is less than 0.5%. This can further improve the detection capabilities of the flat-panel detector and the battery detection device, thereby meeting the detection accuracy requirements of thicker battery cells, more accurately identifying the internal defects of the battery cells, especially the misalignment of the cathode and anode and the distance between the cathode and anode, and improving the accuracy of the detection results.

[0049] The flat panel detectors, battery testing devices, and battery production equipment disclosed in the embodiments of this application can be used in battery production and manufacturing. The battery cells tested or produced can be used, but are not limited to, in electrical devices such as vehicles, ships, and aircraft. Such electrical devices can be equipped with power supply systems comprising the battery cells and batteries disclosed in this application.

[0050] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0051] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0052] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0053] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0054] Please refer to Figure 2, which is a schematic diagram of the exploded structure of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10. The housing 10 provides a storage space for the battery cells 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cells 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder or a rectangular parallelepiped.

[0055] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0056] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0057] Please refer to Figure 3, which is a schematic diagram of the exploded structure of a battery cell 20 provided in some embodiments of the present application. A battery cell 20 is the smallest unit that makes up a battery. As shown in Figure 3, a battery cell 20 includes an end cap 21, a housing 22, a cell assembly 23, and other functional components.

[0058] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to match the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, giving the battery cell 20 greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the battery cell assembly 23 to output or input electrical energy to the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application are not particularly limited in this regard. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0059] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the battery cell assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the battery cell assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any specific limitations on this.

[0060] The battery cell assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more battery cell assemblies 23 may be contained in the shell 22. The battery cell assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active substances constitute the main body of the battery cell assembly, and the parts of the positive and negative electrode sheets without active substances each constitute a tab 23a. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active substance and the negative electrode active substance react with the electrolyte, and the tabs 23a connect the electrode terminals to form a current loop.

[0061] Please refer to Figure 4, which is a schematic diagram of the structure of a battery testing device 400 provided in some embodiments of the present application. Figure 5 is a schematic diagram of the structure of a flat panel detector 430 provided in some embodiments of the present application. The battery testing device 400 includes a carrier assembly 410, a radiation source 420, and a flat panel detector 430.

[0062] The carrier assembly 410 is used to support a battery 411 under test. A radiation source 420 is located at one end of the carrier assembly 410, and the detection radiation 421 emitted by the radiation source 420 is directed toward the battery cell 410. A flat panel detector 430 is located at the other end of the carrier assembly 410 away from the radiation source 420. That is, the flat panel detector 430 and the radiation source 420 are located at opposite ends of the carrier assembly 410, respectively, so that the flat panel detector 430 can be used to receive the detection radiation 421 emitted by the radiation source 410 and penetrating the battery 411 under test. The flat panel detector 430 includes a scintillator layer 431. The thickness of the scintillator layer 431 is greater than a first predetermined thickness, so that the density resolution of the flat panel detector 430 is less than 0.5%.

[0063] The carrying assembly 410 can be any carrying structure that can fix the battery to be tested in a supporting or clamping manner, such as a tray, a clamp, etc. The carrying assembly 410 can be fixed or movable, such as a tray or a clamping mechanism that is provided with a conveying track and moves along the conveying track. The number of batteries 411 to be tested carried on the carrying assembly 410 can be one or more. In one example, the carrying assembly 410 can include multiple trays, each tray carrying one or more batteries 411 to be tested. The battery 411 to be tested can be the battery cell 20 in the above embodiment, or it can be a battery 100 including multiple battery cells 20.

[0064] The ray source 420 is a device for emitting detection rays, and mainly includes a ray tube and a corresponding power supply. The detection rays 421 can be X-rays or other rays. The ray tube can emit corresponding detection rays, such as an X-ray tube or a gamma-ray tube. The ray source 420 can be open (open tube) or closed (closed tube). In one example, the ray source 420 is an X-ray source, and the detection rays 421 it emits are X-rays. When the detection rays 421 emitted by the ray source 420 pass through the battery to be tested 411, due to the differences in the materials of the anode and cathode plates in the battery to be tested 411 (the anode surface is carbon powder, which has weak absorption of rays; the cathode surface is lithium ion material, which has strong absorption of rays), different materials have different absorption rates of X-rays, and there is a gap in the middle of the anode and cathode plates when they are wound. Therefore, the difference in the degree of X-ray absorption can be used to detect the distance between the anode and cathode plates and the amount of misalignment of the anode and cathode plates.

[0065] The flat panel detector 430 is a two-dimensional flat panel detector, which can be an indirect flat panel detector. The scintillator layer 431 can be a film layer structure stacked along the thickness direction of the flat panel detector 430. The scintillator layer 431 is a uniform layer of scintillator material located on the side facing the radiation source 420. It can receive attenuated X-rays that pass through the battery under test 411 and convert them into visible light.

[0066] The thickness t of the scintillator layer 431 refers to the thickness dimension along the thickness direction of the flat panel detector 430. It can be understood that, considering factors such as manufacturing accuracy, the value of the thickness t of the scintillator layer 431 at different positions may be different. At this time, the thickness t of the scintillator layer 431 is greater than the first preset thickness, which means that the minimum thickness of the scintillator layer 431 can also meet the requirement of being greater than the first preset thickness.

[0067] Density resolution, also known as low-contrast resolution, refers to the ability of an image to distinguish the smallest density difference between two tissues under low-contrast conditions. If the grayscale change in the region of interest after penetrating the object is less than the density resolution of the flat-panel detector, the detector will be unable to accurately distinguish the grayscale change in the region of interest, hindering the algorithm from capturing and identifying the image features of the region of interest. The density resolution of the flat-panel detector 430 can be measured using the low-density resolution test method specified in industry standard YY / T 0741-2018.

[0068] The main factors affecting the density resolution of flat panel detector 430 include object size, noise, and signal-to-noise ratio. Noise and signal-to-noise ratio are determined by detector efficiency and X-ray dose. Higher efficiency and higher dose result in higher signal-to-noise ratios, which in turn improves density resolution. It is understood that the smaller the density resolution of flat panel detector 430, the higher its low-contrast resolution and the higher the detection accuracy.

[0069] To determine whether the density resolution of the flat panel detector meets the detection requirements of the battery 411 to be tested, the density contrast of the single-layer electrode in the battery 411 to be tested can be calculated and compared with the density resolution of the flat panel detector 430. For example, the density contrast U of the innermost cathode electrode in the battery 411 to be tested can be calculated according to the following formula:

[0070] Wherein, N is the number of windings of the cathode sheet, X1 is the cold-pressed thickness of the cathode sheet, X2 is the thickness of the cathode foil, ρ1 is the density of the cathode foil, M1 is the cathode compaction density, Y1 is the cold-pressed thickness of the anode sheet, Y2 is the thickness of the anode foil, ρ2 is the density of the anode foil, and M2 is the anode compaction density.

[0071] The density contrast U of the cathode sheet in the innermost circle of the battery is negatively correlated with the number of winding turns N of the cathode sheet. The larger the number of winding turns N of the cathode sheet, the smaller the density contrast U of the cathode sheet. When the density contrast U of the cathode sheet is lower than the density resolution of the flat-panel detector 430, the flat-panel detector 430 will not be able to accurately present the grayscale changes of the cathode sheet in the innermost circle of the battery in the image, which is not conducive to the detection of internal defects of the battery, such as the misalignment of the cathode and anode sheets or the detection of the distance between the cathode and anode sheets.

[0072] In some examples, the scintillator layer 431 of the flat panel detector 430 has a thickness t of 400 micrometers (μm) and a density resolution of 0.5%. When the number of cathode sheet windings N is 47, the density contrast ratio U of the innermost cathode sheet is 0.53%, which is greater than the density resolution of the flat panel detector 430, indicating that the flat panel detector 430 can meet the detection requirements of the innermost cathode sheet of the battery under test 411. When the number of cathode sheet windings N is 76, the density contrast ratio U of the innermost cathode sheet is 0.39%, which is lower than the density resolution of the flat panel detector 430.

[0073] Increasing the radiation dose requires increasing the power of the radiation source, which increases the source's workload. This increased power also increases the source's focal spot size. A larger focal spot size, however, reduces the flat-panel detector's resolution. Increasing the thickness of the scintillator layer 431 can improve X-ray conversion efficiency. At the same dose, a flat-panel detector 430 with a thicker scintillator layer 431 generates more photon signals, making the grayscale difference between the inner cathode and anode plates more pronounced. Further increasing the number of turns of the cathode plate within the battery under test 411 can increase the thickness of the scintillator layer 431 of the flat-panel detector 430, reducing its density resolution and thus meeting the density resolution requirements for detecting ultra-thick batteries under test.

[0074] By adjusting the thickness of the scintillator layer 431 of the flat-panel detector 430 so that the density resolution of the flat-panel detector 430 is less than 0.5%, the detection capability of the battery detection device 400 and the thickness size range of the battery to be tested that can meet the density resolution requirements are improved, which is beneficial to improving the accuracy of the detection results of the battery to be tested 411, and can realize the detection of batteries to be tested of different specifications, while taking into account the economy of battery detection.

[0075] According to some embodiments of the present application, the thickness t of the scintillator layer 431 is less than the second preset thickness, so that the ratio α of the output image contrast to the input image contrast of the flat panel detector 430 satisfies: 50%≤α<1.

[0076] The ratio of the contrast of the flat panel detector 430's output image to the contrast of the input image can be expressed using the flat panel detector's modulation transfer function (MTF). The MTF describes the system's ability to reproduce the spatial frequency range of the imaged object and reflects the imaging system's spatial resolution. When reproducing details of the imaged object, the flat panel detector 430 inevitably experiences varying degrees of attenuation. This means that every image obtained by the imaging system suffers from varying degrees of contrast loss. Therefore, the MTF is always less than 1. The larger the MTF value, the greater the flat panel detector's ability to reproduce details of the imaged object.

[0077] The modulation transfer function of the flat panel detector 430 can be obtained by measurement, for example, using the boundary method. Increasing the thickness of the scintillator layer 421 helps improve the density resolution of the flat panel detector, but it also causes a decrease in the modulation transfer function and spatial resolution, reducing the flat panel detector's ability to resolve image detail and blurring the edge features of the object being tested. When testing the battery 411 to be tested, both the density resolution and spatial resolution must meet certain requirements to improve the accuracy of the test results. Therefore, when designing the thickness of the scintillator layer 431 of the flat panel detector 430, the modulation transfer function of the flat panel detector must also be taken into consideration to meet the requirements for detection accuracy.

[0078] Reasonable selection of the thickness of the scintillator layer 431 can enable the flat panel detector 430 to take into account both density resolution and spatial resolution, thereby better adapting to the internal detection of thicker batteries to be tested, improving the quality of the detection image, and thus helping to improve the accuracy of defect detection in the batteries to be tested.

[0079] According to some embodiments of the present application, the quantum detection efficiency λ of the flat panel detector 430 satisfies: 0.5≤λ<1.

[0080] Detective Quantum Efficiency (DQE) is an expression of the imaging system's ability to transmit signal and noise from input to output, expressed as a percentage. DQE reflects the sensitivity, noise, X-ray dose, and density resolution of a flat-panel detector. Flat-panel detectors with higher quantum detection efficiency can achieve better image quality at lower radiation doses. The quantum detection efficiency λ can be expressed as:

[0081] The higher the quantum detection efficiency λ (the maximum value is 1, i.e., 100% utilization), the higher the effective quantum utilization rate and the higher the output image signal-to-noise ratio. As the scintillator layer thickness increases, the radiation conversion efficiency is improved for the same incident dose, resulting in a higher output image signal-to-noise ratio. This increase in quantum detection efficiency λ also improves the density resolution of the flat-panel detector 430, helping to improve the detection of low-contrast features.

[0082] In some examples, the quantum detection efficiency of a flat panel detector can be measured using the measurement method specified in the International Electrotechnical Commission standard IEC 62220-1, or the measurement method specified in the corresponding industry standard. In other examples, the quantum detection efficiency can also be determined using the following calculation formula: λ = S 2 ×MTF 2 / NPS×X×C,

[0083] Where S is the average signal intensity; MTF is the modulation transfer function; X is the radiation exposure intensity; NPS is the system noise power spectrum; and C is the radiation quantum coefficient.

[0084] By limiting the quantum detection efficiency of the flat panel detector 430 , the sensitivity and density resolution of the flat panel detector 430 can be guaranteed to a certain extent, and the imaging quality of the image can be improved, thereby helping to improve the accuracy of detection image recognition and the accuracy of battery detection results.

[0085] According to some embodiments of the present application, the thickness t of the scintillator layer 431 satisfies: 400 micrometers (μm)<t<1000 micrometers (μm).

[0086] If the thickness of the scintillator layer 431 is too thin, it will affect the density resolution and quantum detection efficiency of the flat panel detector 430. If the thickness of the scintillator layer 431 is too thick, it will affect the modulation transfer function (MTF) of the flat panel detector 430, thereby affecting the spatial resolution of the flat panel detector 430. In some examples, the thickness of the scintillator layer 431 is 400 microns, the density resolution of the flat panel detector 430 is 0.5%, the quantum detection efficiency is 0.5-0.7, and the modulation transfer function (MTF) obtained by boundary method detection is 72%. This can meet the detection requirements of objects requiring a density resolution of 0.5% or above, such as the detection of the misalignment or spacing between the innermost cathode and anode electrodes of a battery 411 under test with less than 47 electrode windings. In some embodiments, the first predetermined thickness can be set to 400 μm and combined with other parameters, such as the voltage or current of the radiation source, to ensure that the density resolution, modulation transfer function, and quantum detection efficiency of the flat panel detector meet the corresponding requirements. When the thickness of the scintillator layer 431 exceeds 1000 μm, although the density resolution of the flat panel detector 430 is high, the modulation transfer function will be significantly reduced, which in turn limits the spatial resolution of the flat panel detector and is detrimental to imaging. Optionally, the thickness t of the scintillator layer 431 can be 500 μm, 600 μm, or 700 μm.

[0087] By properly selecting the thickness range of the scintillator layer 431 in the flat panel detector 430 , the density resolution and spatial resolution performance of the flat panel detector 430 can be taken into consideration, thereby being able to adapt to objects of different sizes and improving the scope of application.

[0088] According to some embodiments of the present application, the thickness t of the scintillator layer 431 satisfies: 600 μm≤t≤700 μm.

[0089] By further selecting an appropriate thickness for the scintillator layer 431, while meeting the requirements for the size of the object being tested, while more appropriately balancing the density resolution and spatial resolution, the detection performance of the flat-panel detector 430 is improved. This allows for image quality requirements for batteries 411 under test with a wider range of thicknesses, thereby helping to improve the accuracy of image recognition and detection results. Optionally, the thickness t of the scintillator layer 431 can be 600 μm, 650 μm, or 700 μm.

[0090] According to some embodiments of the present application, the density resolution β of the flat panel detector 430 satisfies: 0<β≤0.38%.

[0091] The smaller the density resolution, the higher the density resolution capability of the flat panel detector 430, and the higher the detection accuracy. This allows the flat panel detector 430 to better meet the detection accuracy requirements for very thick batteries 411 under test. For example, if the cathode sheet in the battery 411 under test has 76 turns, the corresponding density contrast ratio U is 0.39%. In order for the flat panel detector 430 to distinguish between the innermost cathode sheet and the anode sheet, the density resolution of the flat panel detector 430 must not exceed 0.39%. This is necessary to meet the detection requirements for batteries 411 under test with fewer than 76 turns of the anode sheet. It is understood that although the density resolution of the flat panel detector 430 is negatively correlated with the thickness of the scintillator layer, the factors that determine the density resolution are not limited to the thickness of the scintillator layer. This means that, given a certain scintillator layer thickness, the density resolution β can be adjusted to meet the following conditions: 0 < β ≤ 0.38% by adjusting other parameters, such as adjusting the X-ray dose or reducing the focal spot size.

[0092] By further limiting the value range of the density resolution of the flat panel detector 430, the detection capability of the flat panel detector 430 can be better matched with the thickness of the object to be tested, the size range of the battery 411 to be tested that the flat panel detector 430 is compatible with can be increased, the time for equipment replacement due to insufficient detection accuracy can be reduced, and detection efficiency can be improved.

[0093] According to some embodiments of the present application, the scintillator layer 431 includes cesium iodide, and the photoelectric conversion layer 432 includes an amorphous silicon thin film transistor.

[0094] Flat panel detector 430 is an indirect flat panel detector. It may include a photoelectric conversion layer 432 and a scintillator layer 431 stacked sequentially on a substrate. Scintillator layer 431 is located on the side facing the radiation source 420. This allows it to receive detection radiation that has penetrated the battery under test 411 and generate visible photons. Cesium iodide is an inorganic scintillating crystal that absorbs radiation energy and emits fluorescent photons. It has the advantages of high radiation detection efficiency and high luminescence efficiency. The emitted spectral wavelength is well matched to silicon photodiodes. Due to its higher sensitivity, it uses lower X-ray doses and is relatively safer.

[0095] The flat panel detector with a structure of cesium iodide and thin film transistors has less photon loss, so the quantum detection efficiency of the flat panel detector 430 is relatively high, which can improve the detection efficiency of the flat panel detector 430.

[0096] According to some embodiments of the present application, the radiation source is an integrated radiation source, and the rated voltage V of the radiation source satisfies: 130 kilovolts (kV) ≤ V ≤ 150 kilovolts (kV), and / or the rated current I of the radiation source satisfies: 300 microamperes (μA) ≤ I ≤ 500 microamperes (μA).

[0097] An integrated radiation source, also known as a closed radiation source, adopts an integrated design in which the cathode and anode / target are enclosed in a vacuum tube. This not only increases stability and reduces the repair rate, but also makes the radiation source very small, making it easy to operate and install.

[0098] The maximum photon energy emitted by the X-ray source 420 is equal to the energy acquired by the incident electron in the accelerating electric field of the X-ray tube—the electron charge multiplied by the accelerating electric field. The accelerating electric field is the magnitude of the tube voltage, which is also the rated voltage V of the X-ray source 420. The higher the rated voltage V, the higher the energy of the generated X-rays, the shorter the wavelength, and the greater the ability to penetrate matter.

[0099] The higher the rated current I of the radiation source 420, the more high-speed electrons will bombard the target per unit time, and the more radiation will be emitted by the radiation source 420. This is equivalent to an increase in the radiation dose per a given area, and a corresponding increase in image brightness. However, if the rated voltage or rated current of the radiation source 420 is too high, the focal spot size of the radiation source 420 will be too large, thereby reducing the spatial resolution of the flat-panel detector 430 and hindering subsequent image recognition and defect detection.

[0100] By limiting the type of X-ray tube, rated voltage V, and rated current I, it is possible to provide a detection X-ray dose that meets the requirements while taking into account the stability and reliability of the X-ray source. At the same time, the X-ray source and the flat-panel detector can cooperate with each other to meet the detection accuracy requirements for batteries under test with a wider thickness range, thereby improving the efficiency and accuracy of detection.

[0101] According to some embodiments of the present application, the maximum size d of the focus of the ray source satisfies: 0<d≤80μm.

[0102] The focal size of a X-ray source refers to the size of the focal point along a certain direction parallel to the plane where the focal point lies. When other conditions are the same, the smaller the focal point, the higher the resolution and the better the imaging quality. Common methods for measuring the focal size of X-ray sources are divided into direct and indirect methods. The direct method refers to directly observing the shape and size of the focal point, such as the pinhole method. The indirect method calculates the focal size by observing the point spread function or line spread function caused by the focal size, including the knife edge method, the slit method, and the ball target method. It can also be tested by referring to the methods specified in relevant measurement standards, such as the measurement methods listed in GB / T26834-2011.

[0103] The focal spot size is directly related to the image resolution of the battery detection device. Specifically limiting the focal spot size can better match the detection accuracy of the battery detection device with the size of the battery to be tested, thereby improving the detection accuracy and efficiency.

[0104] According to some embodiments of the present application, the battery testing device 400 further includes a processor 440 , which is connected to the flat panel detector 430 . The processor 440 is configured to receive an electrical signal from the flat panel detector 430 to output a test result of the battery 411 to be tested.

[0105] Processor 440 can be a computer device that receives electrical signals from flat-panel detector 430 to restore an image of the object being tested. Processor 440 can also preset a corresponding image recognition algorithm to identify the detection image, obtain corresponding detection results, and determine whether the battery under test 411 has an abnormality based on the detection results. In one example, processor 440 can identify the detection image to obtain parameters such as the misalignment of the cathode and anode plates and / or the distance between the cathode and anode plates within the battery under test 411, compare these parameters with preset thresholds, and output a corresponding detection result based on the comparison result.

[0106] By setting the processor 440 to receive the image signal generated by the flat panel detector 430 and identify the detected image to output the detection result of the battery to be tested 411, automatic detection of internal defects of the battery to be tested can be achieved, thereby improving the automation level and detection efficiency of the battery detection device.

[0107] In a second aspect of the present application, an embodiment provides a flat panel detector 430, comprising a scintillator layer 431 and a photoelectric conversion layer 432 stacked along a thickness direction. The scintillator layer 431 is configured to receive detection radiation 421 and emit visible light; the photoelectric conversion layer 432 receives the visible light emitted by the scintillator layer 431 and generates a corresponding electrical signal. The thickness of the scintillator layer 431 is greater than a first predetermined thickness, such that the density resolution of the flat panel detector 430 is less than 0.5%.

[0108] The flat panel detector 430 is positioned at the end of the test object, away from the radiation source. It is used to receive detection radiation 421 emitted by the radiation source that has penetrated the test object. The test object can be a battery 411 under test. A scintillator layer 431 and a photoelectric conversion layer 432 can be sequentially arranged on the substrate of the flat panel detector 430. The scintillator layer 432 is located on the side facing the radiation source to receive detection radiation 421 that has penetrated the battery 411 under test and emit visible light. The photoelectric conversion layer 432 receives the visible light emitted by the scintillator layer 431 and generates a corresponding electrical signal.

[0109] The photoelectric conversion layer 432 can be a thin film transistor (TFT), a charge coupled device (CCD), or a complementary metal oxide semiconductor (CMOS). In some examples, the photoelectric conversion layer 432 can include a photodiode circuit and a charge readout circuit. The photodiode circuit converts the visible light emitted by the scintillator layer 431 into an electrical signal, forming a stored charge on the capacitor of the photodiode itself. The amount of stored charge in each pixel is proportional to the intensity of the incident X-ray. The charge readout circuit scans and reads the stored charge of each pixel under the action of the control circuit, outputs a digital signal after A / D conversion, and transmits it to a computer for image processing to form an X-ray digital image.

[0110] The flat panel detector of this embodiment can further improve the density resolution when the detection radiation dose is constant, thereby meeting the detection requirements of batteries 411 to be tested with a larger size range, improving the imaging quality, and further improving the accuracy of internal defect detection of the battery 411 to be tested.

[0111] In some embodiments, the thickness of the scintillator layer 431 is less than a second preset thickness, so that a ratio α of the contrast ratio of an output image to an input image of the flat panel detector 430 satisfies: 50%≤α<1.

[0112] The thickness of the scintillator layer 431 is further limited so that the spatial resolution of the flat panel detector 430 can meet preset requirements, which can enable the flat panel detector 430 to take both density resolution and spatial resolution into consideration, thereby improving the imaging quality of the image.

[0113] In some embodiments, the thickness t of the scintillator layer 431 satisfies: 600 μm≤t≤700 μm, the quantum detection efficiency λ of the flat panel detector 430 satisfies: 0.5≤λ<1, and the density resolution β of the flat panel detector satisfies: 0<β≤0.38%.

[0114] By selecting a suitable thickness of the scintillator layer 431 , the flat panel detector 430 can have more balanced quantum detection efficiency, density resolution, and spatial resolution, thereby meeting the detection accuracy requirements for thicker batteries to be tested and improving the applicability of the flat panel detector.

[0115] An embodiment of a third aspect of the present application provides a battery production device, including the battery detection device 400 in the above embodiment.

[0116] The battery production equipment includes a battery testing device 400, which can perform non-destructive testing on the battery 411 to be tested during its production process, timely discover defects inside the battery 411 to be tested, thereby eliminating unqualified batteries 411 to be tested and improving the quality of the batteries 411 to be tested.

[0117] The battery detection device of the present application is further described below with reference to a specific embodiment.

[0118] As shown in FIG. 4 to FIG. 6 , the battery detection device 400 includes a carrier assembly 410 , a radiation source 420 , a flat panel detector 430 , and a processor 440 .

[0119] The carrier assembly 410 can be a tray or a clamping mechanism similar to a clamp, used to carry the battery under test 411. The carrier assembly 410 can be configured to be movable so that the battery under test 411 can be moved into and out of the detection area between the radiation source 430 and the flat panel detector 430. The carrier assembly 410 can be made of a low-density material, such as carbon fiber, to reduce the carrier assembly 410's absorption of the detection radiation.

[0120] The radiation source 420 is located at one end of the carrier assembly 410, and the detection radiation 421 of the radiation source 420 is emitted toward the battery under test 411. The radiation source 420 can be an integrated micro-focus X-ray source with a rated voltage V meeting the following conditions: 130kV≤V≤150kV, a rated current I meeting the following conditions: 300μA≤I≤500μA, and a focal spot diameter d meeting the following conditions: 0<d≤80μm

[0121] The flat panel detector 430 is located at the other end of the carrier assembly 410 away from the radiation source 420. It is used to receive detection radiation 421 emitted by the radiation source and penetrating the battery under test 411. The flat panel detector 430 comprises a scintillator layer 431 and a photoelectric conversion layer 432 stacked along the thickness direction. The scintillator layer 431 is configured to receive the detection radiation 421 that has penetrated the battery under test 411 and emit visible light. The photoelectric conversion layer 432 receives the visible light emitted by the scintillator layer 431 and generates a corresponding electrical signal. The scintillator layer 431 comprises cesium iodide, and the photoelectric conversion layer 432 comprises amorphous silicon thin-film transistors. The thickness t of the scintillator layer 431 satisfies the following conditions: 600 μm ≤ t ≤ 700 μm. The density resolution β of the flat panel detector 430 satisfies the following conditions: 0 < β ≤ 0.38%. The ratio α of the contrast ratio of the output image of the flat panel detector 430 to the contrast ratio of the input image satisfies the following conditions: 50% ≤ α < 1. The quantum detection efficiency λ satisfies the following conditions: 0.5 ≤ λ < 1.

[0122] As shown in FIG6 , the detection method of the battery detection device 400 includes the following steps:

[0123] Step S501: calibrate the flat panel detector.

[0124] To ensure image quality, flat-panel detector 430 calibration is required before powering on. Before calibration, ensure there is no obstruction between flat-panel detector 430 and radiation source 420, including the carrier assembly 410 and any debris. Turn on radiation source 420 to capture bright-field images. Afterward, turn off radiation source 420 to capture dark-field images. Repeat this process three times, capturing 19 images each time. After calibration, reactivate the calibration template.

[0125] Step S502: Calibrate the battery detection device.

[0126] Before calibration, ensure that there are no batteries 411 to be tested or any other debris between the X-ray source 420 and the flat-panel detector 430. Place the calibration block provided with the device on the test platform and adjust the scale on the block so that the height of the pin gauge mounted on the block is half the height of the battery 411 to be tested. Turn off the device, turn on the X-ray source 420, and move the pin gauge to the center of the image. Maintain the relative position of the X-ray source 420 and the flat-panel detector 430 as during the battery test. Open the calibration software interface and enter the pin gauge diameter. The software will automatically record and save the magnification factor.

[0127] Step S503: transport the battery to be tested to a testing station.

[0128] The carrier assembly 410 is driven to move, and the batteries to be tested 411 are sequentially transferred to the detection position between the radiation source 420 and the flat panel detector 430 and then stops moving, waiting for X-rays to be turned on and detected.

[0129] Step S504: Start X-ray detection and save the image.

[0130] After setting the rated voltage and rated current of the ray source 420 during detection, the X-rays are turned on to penetrate the battery 411 to be tested. The flat panel detector 430 receives the X-rays that penetrate the battery 411 to be tested and converts them into images. The processor then reads and saves the images.

[0131] Step S505: The algorithm identifies whether there are defects in the image.

[0132] Through deep learning algorithms, the misalignment and spacing between the cathode and anode sheets in each layer of the battery 411 under test in the image are identified and measured. The specific determination steps include:

[0133] Step S506: Determine OK and discharge normally. If the anode-cathode misalignment and the distance between the anode and cathode electrodes detected in the image are within the preset threshold range, the image is determined to be OK and the corresponding battery 411 to be tested is discharged normally.

[0134] Step S507: Determine NG and reject. If the detected misalignment of the cathode and anode pieces and / or the distance between the cathode and anode pieces exceeds the preset threshold range, the image is determined to be NG and the corresponding battery 411 to be tested is automatically rejected to prevent defective products from being discharged.

[0135] According to the description in the above embodiment, in some embodiments, the density contrast ratio U of the battery under test 411 with 76 turns of the electrode is 0.39%. When other conditions are kept the same and the thickness of the scintillator layer 431 is different, the performance indicators of the flat panel detector 430 are shown in the following table:

[0136] As can be seen from the table above, when the scintillator layer thickness is below 400μm, for example, at 150μm, the quantum detection efficiency is low, only 0.23-0.33, and the density resolution is relatively high, at 1.07%. This makes it difficult to meet the density resolution requirements for testing ultra-thick batteries, such as those with more than 47 electrode windings. When the scintillator layer thickness is 1000μm, the modulation transfer function is only 43.6%, and the modulation transfer function continues to decrease with the scintillator layer thickness. This in turn affects the spatial resolution of the flat-panel detector, making it impossible to accurately distinguish the boundaries of adjacent fine structures on the electrode, thereby affecting the accuracy and reliability of image recognition results. In some embodiments of the present application, limiting the thickness of the scintillator layer to between 400-1000 μm can well take into account the spatial resolution and density resolution of the flat-panel detector. In other embodiments, limiting the thickness of the scintillator layer to between 600-700 μm can better meet the detection accuracy requirements of ultra-thick battery cells with a winding number of less than 76 turns. Further optimizing the rated voltage, rated current and focal size of the radiation source can enable the radiation source and the flat-panel detector of the battery detection device to cooperate together, further improving the resolution and image quality of the detection image of the battery detection device for the thicker battery to be tested, thereby helping to improve the accuracy of the detection results of the battery to be tested.

[0137] FIG7 shows a detection image when the thickness of the scintillator layer 431 of the flat panel detector 430 of the battery testing apparatus 400 is 400 μm and the number of turns of the electrode piece of the battery under test 411 is 76. FIG8 shows a detection image when the thickness of the scintillator layer 431 of the flat panel detector 430 of the battery testing apparatus 400 is 600 μm and the number of turns of the electrode piece of the battery under test 411 is 76. FIG9 shows a detection image when the thickness of the scintillator layer 431 of the flat panel detector 430 of the battery testing apparatus 400 is 700 μm and the number of turns of the electrode piece of the battery under test 411 is 76.

[0138] As shown in Figures 7-9, regions P1, P2, and P3 in the detection images are located within the innermost electrode of the battery under test 411. The endpoints of the electrode near the innermost circle in region P1 of Figure 7 are relatively blurred. This makes it difficult to determine the electrode endpoints and center positions using algorithms during recognition, making it impossible to calculate accurate detection parameters, such as the offset and spacing between the cathode and anode electrodes. This indicates that the flat-panel detector 430 cannot distinguish the innermost electrode from the surrounding structure based on contrast, meaning that the density resolution does not meet detection requirements. The electrode position in region P2 of Figure 8 is clearer than in region P1. The image recognition algorithm can generally determine the electrode position, allowing a rough assessment of whether the battery under test has defects. The electrode position in region P3 of Figure 9 is even clearer, clearly showing the position of the innermost cathode electrode, including its endpoints. This facilitates accurate acquisition of corresponding parameters, such as the offset and spacing between the cathode and anode electrodes, during image recognition, thus accurately determining whether the battery under test meets quality requirements.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery detection device, comprising: The carrying component is used to carry the battery to be tested. A ray source is located at one end of the bearing assembly, and the ray source emits detection rays toward the battery to be tested; and A flat panel detector is located at the other end of the supporting assembly away from the radiation source, and is used to receive detection radiation emitted by the radiation source and penetrating the battery to be tested. The flat panel detector includes a scintillator layer, and the thickness of the scintillator layer is greater than a first preset thickness so that the density resolution of the flat panel detector is less than 0.5%.

2. The battery testing device according to claim 1, wherein: The thickness of the scintillator layer is less than a second preset thickness, so that a ratio α of the contrast ratio of an output image to an input image of the flat panel detector satisfies: 50%≤α<1.

3. The battery testing device according to claim 1 or 2, wherein: The quantum detection efficiency λ of the flat panel detector satisfies: 0.5≤λ<1.

4. The battery testing device according to any one of claims 1 to 3, wherein: The thickness t of the scintillator layer satisfies: 400 μm<t<1000 μm.

5. The battery testing device according to claim 4, wherein: The thickness t of the scintillator layer satisfies: 600 μm≤t≤700 μm.

6. The battery testing device according to any one of claims 1 to 5, wherein: The density resolution β of the flat panel detector satisfies: 0<β≤0.38%.

7. The battery testing device according to any one of claims 1 to 6, wherein: The flat panel detector further includes a photoelectric conversion layer stacked with the scintillator layer, the scintillator layer includes cesium iodide, and the photoelectric conversion layer includes an amorphous silicon thin film transistor.

8. The battery testing device according to any one of claims 1 to 7, wherein: The rated voltage V of the radiation source satisfies: 130kV≤V≤150kV, and / or The rated current I of the ray source satisfies: 300μA<I≤500μA.

9. The battery testing device according to any one of claims 1 to 8, wherein: The maximum size d of the focus of the ray source satisfies: 0<d≤80μm.

10. The battery testing device according to any one of claims 1 to 9, wherein: Also includes: A processor is connected to the flat panel detector, and is used to receive the electrical signal of the flat panel detector to output the detection result of the battery to be tested.

11. A flat panel detector comprising a scintillator layer and a photoelectric conversion layer stacked in a thickness direction; The scintillator layer is configured to receive the detection radiation to emit visible light; The photoelectric conversion layer receives the visible light emitted by the scintillator layer to generate a corresponding electrical signal; in, The thickness of the scintillator layer is greater than a first preset thickness, so that the density resolution of the flat panel detector is less than 0.5%.

12. The flat panel detector according to claim 11, wherein: The thickness of the scintillator layer is less than a second preset thickness, so that a ratio α of the contrast ratio of an output image to an input image of the flat panel detector satisfies: 50%≤α<1.

13. The flat panel detector according to claim 11 or 12, wherein: The thickness t of the scintillator layer satisfies: 600 μm≤t≤700 μm, the quantum detection efficiency λ of the flat panel detector satisfies: 0.5≤λ<1, and the density resolution β of the flat panel detector satisfies: 0<β≤0.38%.

14. A battery production equipment, comprising the battery testing device according to any one of claims 1 to 10.

15. A battery detection method, using the battery detection device according to any one of claims 1 to 10, the method comprising: Transfer the battery to be tested to the testing station; Acquire a detection image of the battery to be tested; The inspection image is recognized to determine whether the battery to be inspected has defects.

Images