A battery electrochemical reaction mold and a continuous rotation imaging method for in-situ observation in X-ray CT

Abstract

This invention discloses a battery electrochemical reaction mold and a continuous rotation imaging method for in-situ X-ray CT observation. The mold includes a base, a capillary shell sealed above the base, and a sealing cover sealed to the top of the shell. Microelectrode assemblies are housed within the base and the sealing cover. A metal pin is located at the bottom of the base, and a top-mounted liquid-phase conductive groove filled with a room-temperature liquid alloy medium is formed at the top of the sealing cover to create a liquid-immersed lubricating kinetic-electrical contact with the external stationary electrode pin. This invention eliminates beam hardening artifacts caused by the solid separator and thick-walled shell, achieves stable electrical conduction with zero mechanical torque, and precisely suppresses motion blur caused by dynamic reactions. It also enables high-fidelity, sub-micron-level dynamic tracking of the microstructure and microcrack evolution of battery materials.

Description

Technical Field

[0001] This invention relates to the field of in-situ battery testing, specifically to a battery electrochemical reaction mold and a continuous rotation imaging method for in-situ X-ray CT observation. Background Technology

[0002] In battery material research, structural degradation, such as volume expansion, particle pulverization, and microcrack evolution, that occurs in electrode materials during charge-discharge cycles is the core mechanism leading to the decay and failure of the electrochemical performance of active materials. High-resolution X-ray computed tomography (CT) technology, as a three-dimensional non-destructive imaging method, is an important tool for observing the evolution of the internal microstructure of materials.

[0003] However, conventional in-situ CT testing devices face significant technical bottlenecks when adapting to high-resolution dynamic imaging. To maintain mechanical compression and sealing, conventional molds often use thick-walled metal or high-thickness polymers as pressure-bearing shells. According to the Beer-Lambert law, such structures absorb a large number of effective photons under low-energy X-ray irradiation, causing severe beam hardening artifacts, resulting in a significant reduction in spatial resolution and signal-to-noise ratio. If the outer diameter of the mold is reduced to improve X-ray transmittance, existing microstructures are prone to leakage of trace amounts of electrolyte. Furthermore, due to the lack of a micron-level three-dimensional coaxial adjustment mechanism, the micro-electrode material is highly susceptible to eccentricity and deviation from the detection field of the CT equipment during dynamic rotation.

[0004] Meanwhile, in terms of signal transmission and data reconstruction, existing devices mostly rely on physical cables or dry metal slip rings for dynamic power supply. The solid sliding friction torque and high-frequency micro-vibrations generated by continuous rotation can easily cause irregular drift of the geometric focus, introducing severe oscillation artifacts. In addition, the electrode material is in a rheological process of continuous morphological evolution under current drive, while traditional reconstruction algorithms (such as the conventional FDK algorithm) assume that the sample morphology is absolutely static during the scanning cycle. Applying this to the continuously evolving projection data stream will result in severe stripe artifacts and temporal ghosting (i.e., motion blur) in the reconstructed three-dimensional volume data. Since the light element components in the electrode material have extremely weak absorption of X-rays, conventional absorption contrast imaging is also unable to provide a sufficient signal-to-noise ratio to identify microscopic phase interfaces.

[0005] Therefore, how to develop a battery electrochemical reaction mold and a continuous rotation imaging method for in-situ observation of X-ray CT, so as to eliminate mechanical friction vibration during hardware rotation and beam hardening artifacts caused by the shell, overcome motion blur and weak contrast of light elements caused by electrochemical dynamic evolution, and thus achieve high-quality, high-resolution dynamic three-dimensional reconstruction of the microstructure degradation process of electrode materials in in-situ, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the technical shortcomings of existing battery in-situ CT testing devices in tracking in-situ electrochemical reactions of electrode materials, such as high X-ray attenuation and beam hardening artifacts due to excessively thick shells, mechanical friction vibration and focus drift caused by continuous rotation, dynamic motion blur caused by continuous morphological evolution, and difficulty in identifying interfaces due to low contrast of light elements, the purpose of this invention is to provide a battery electrochemical reaction mold and a continuous rotation imaging method for in-situ X-ray CT observation, so as to achieve high-quality dynamic three-dimensional structural reconstruction of the microstructure evolution process of electrode materials under in-situ electrochemical conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A battery electrochemical reaction mold for in-situ X-ray CT observation includes:

[0009] The base has metal pins fixed to its bottom;

[0010] The capillary housing is sealed and connected above the base;

[0011] A sealing cover is sealed to the top of the capillary shell. The top of the sealing cover has a top liquid phase conductive groove. The top liquid phase conductive groove is filled with a room temperature liquid alloy electrode medium, which is used to form a liquid immersion lubricating kinetic contact with the external electrode needle located above the mold and kept stationary.

[0012] The base and the sealing cover are equipped with microelectrode components.

[0013] As a further improvement of the present invention, the microelectrode assembly includes a first microelectrode extending upward from the interior of the base, and a second microelectrode extending downward from the interior of the sealing cover.

[0014] The metal pin is electrically connected to the first microelectrode; the top of the second microelectrode penetrates vertically upward along the central axis of the mold through the bottom wall of the sealing cover, and its top end extends directly into the interior of the top liquid phase conductive tank.

[0015] As a further improvement of the present invention, the tip of the first microelectrode and the bottom of the second microelectrode define a micro-region reaction chamber within the capillary shell, and a gap is left between the tips of the two electrodes.

[0016] The first microelectrode has a group of microparticles of the active substance to be tested at its top end, and the gap is filled with a trace amount of test electrolyte. The test electrolyte forms a membrane-free liquid bridge conduction path by relying on surface tension.

[0017] Preferably, the tip curvature radius of the first microelectrode is 1 μm to 10 μm, and the bottom end of the second microelectrode is a flat end face or a passivated ball head with a curvature radius of 50 μm to 100 μm.

[0018] As a further improvement of the present invention, the two ends of the capillary shell are airtightly encapsulated between the base and the sealing cover by built-in corrosion-resistant O-rings and threaded clamping structures.

[0019] Preferably, the capillary shell is made of polyimide, quartz, or beryllium, and the wall thickness of the corresponding core area of ​​the viewing window ranges from 10 μm to 100 μm.

[0020] The synergistic effect of the aforementioned material and thin-walled dimensions gives the capillary shell low X-ray absorption characteristics, providing a photon transmittance of more than 85% under broadband X-ray irradiation of 30 kV to 160 kV.

[0021] Preferably, the total axial length of the capillary shell ranges from 15 mm to 25 mm, the outer diameter ranges from 1.5 mm to 2.5 mm, and the inner diameter ranges from 1.3 mm to 2.3 mm.

[0022] Preferably, the room-temperature liquid alloy electrode medium is a gallium indium tin alloy or a gallium indium alloy.

[0023] Preferably, the base and the sealing cover are each made of one of the following materials: polyetheretherketone, polytetrafluoroethylene, polyimide, or electrolyte-resistant resin.

[0024] Preferably, the maximum outer diameter of the base is in the range of 12 mm to 15 mm, and the axial height is in the range of 18 mm to 25 mm; the maximum outer diameter of the sealing cover is in the range of 8 mm to 10 mm, and the axial height is in the range of 10 mm to 15 mm.

[0025] Preferably, the outer diameter of the metal pin is 3.2 mm, and the axial downward extension length is 12 mm to 15 mm.

[0026] Preferably, the materials of the first microelectrode and the second microelectrode are each independently tungsten, platinum, gold, stainless steel, titanium, aluminum, carbon fiber or glassy carbon, and any one or more combinations thereof.

[0027] A method for in-situ electrochemical continuous rotational imaging of a battery includes the following steps:

[0028] S1. Battery assembly: Under inert atmosphere conditions, the active material to be tested is fixed on the tip of the first microelectrode and adjusted to the center of rotation of the mold; the active metal of the counter electrode is loaded in the micro-region at the bottom of the second microelectrode; the capillary shell, base, and sealing cover are hermetically sealed and electrolyte is injected to form a liquid bridge.

[0029] S2. Device loading: Fix the metal pin inside the rotating sample stage of the CT equipment; immerse the tip of the external stationary electrode into the room temperature liquid alloy electrode medium in the top liquid phase conductive tank.

[0030] S3. In-situ electrochemical and CT combined test: Apply charge and discharge signals and start CT test at the same time. The rotating sample stage drive device rotates continuously. X-rays penetrate the capillary shell horizontally and the detector continuously collects projection data.

[0031] S4. Dynamic geometric center correction: Extract projection data pairs, calculate the geometric centroid trajectory and perform spatial coordinate translation compensation;

[0032] S5. Spatiotemporal Joint Blur Suppression and Phase Contrast Reconstruction: A spatiotemporal joint iterative reconstruction model is constructed, which includes a time weighting factor and a first-order forward difference L1 norm term of the time axis as regularization constraints, to suppress motion blur caused by dynamic evolution of morphology; at the same time, Fresnel diffraction signals at a preset propagation distance are collected to decouple the phase shift signal, and an edge enhancement operator is introduced in the reconstruction to reconstruct the three-dimensional structural data of the micro-particle group inside the battery.

[0033] Preferably, in step S4, the opposing projection image pairs with a relative rotation angle of 180° are extracted from the projection data stream, the spatial boundary geometric centroid trajectory of the outer edge of the capillary shell is identified, the trajectory is fitted into a spatial sine curve using the least squares method, the eccentric axis drift is solved in reverse, and translation and rotation compensation are implemented.

[0034] Preferably, in step S5, the time difference regularization constraint term is expressed as: ,in For the forward difference operator along the time axis, This is a volumetric data sequence showing the evolution of the three-dimensional shape to be reconstructed over time. This is the regularization parameter.

[0035] Preferably, in step S5, the preset propagation distance is 250 mm.

[0036] Preferably, in step S5, the objective function of the spatiotemporal joint iterative reconstruction model is:

[0037]

[0038] In the formula, For the forward difference operator along the time axis, This is a volumetric data sequence showing the evolution of the three-dimensional shape to be reconstructed over time. The system projection matrix, This is a geometrically corrected two-dimensional projection data stream based on actual measurements. This is the time difference regularization parameter.

[0039] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0040] (1) High X-ray transmittance and low artifacts: The present invention adopts a capillary shell with low X-ray absorption characteristics and a diaphragm-free design with suspended liquid bridge, which removes excess material in the X-ray penetration path. Under broadband X-ray irradiation of 30 kV to 160 kV, it can provide an ultra-high photon transmittance of more than 85%, which blocks the high attenuation effect and strong beam hardening artifacts caused by traditional thick-walled in-situ cells from the physical source, and significantly improves the signal-to-noise ratio of submicron structure resolution.

[0041] (2) Zero mechanical torque electrical conduction: The present invention uses a room temperature liquid alloy top liquid phase conductive tank, and an external stationary electrode needle is suspended and immersed in the liquid alloy to achieve liquid immersion electrical conduction under 360° continuous rotation. The viscous resistance of the fluid is used to replace the solid dry friction, eliminating the mechanical vibration, focus drift and rotational motion ambiguity caused by dry friction.

[0042] (3) High-precision dynamic geometric correction: This invention identifies the spatial boundary geometric centroid trajectory of the outer edge of the capillary shell by projecting images, fits the spatial sine curve using the least squares method, solves the eccentric axis drift in reverse and implements translation and rotation compensation, effectively eliminating the micro-amplitude mechanical oscillation and eccentric drift caused by continuous rotation.

[0043] (4) Motion blur suppression and phase contrast enhancement: This invention introduces a spatiotemporal joint iterative reconstruction model and utilizes the sparsity physical prior of the electrochemical reaction time domain to accurately suppress motion blur caused by dynamic morphology evolution; at the same time, it collects Fresnel diffraction signals to decouple phase shift signals and introduces edge enhancement operators, which significantly improves the contrast of light element phase interfaces, providing high spatiotemporal resolution for tracking the evolution of microcracks and non-rigid strain fields in battery materials, and has important scientific research and engineering application value. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall three-dimensional assembly of the battery electrochemical reaction mold for in-situ X-ray CT observation according to the present invention;

[0045] Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of the battery electrochemical reaction model for in-situ X-ray CT observation according to the present invention.

[0046] Figure 3 This is a flowchart of the steps of the battery electrochemical reaction mold for in-situ X-ray CT observation according to the present invention.

[0047] In the figure: 1-base; 2-capillary shell; 3-sealing cover; 4-first microelectrode; 5-second microelectrode; 6-top liquid phase conductive tank; 11-metal pin. Detailed Implementation

[0048] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Example 1

[0051] like Figure 1 and Figure 2 As shown, this embodiment provides a battery electrochemical reaction mold for in-situ X-ray CT observation, including a base 1, a capillary shell 2, a sealing cover 3, a microelectrode assembly, and a top-mounted liquid phase conductive tank 6.

[0052] The capillary shell 2 is sealed at both ends with built-in corrosion-resistant O-rings and threaded clamping structures to provide an airtight seal between the base 1 and the sealing cover 3. The sealing cover 3 is sealed at the top of the capillary shell 2 in the same airtight manner, thereby defining an independent non-in-situ / in-situ reaction chamber that is isolated from the external water and oxygen environment inside the mold.

[0053] Preferably, the base 1 and the sealing cover 3 are made of one of polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), polyimide (PI), or an electrolyte-resistant resin.

[0054] In this embodiment, the base 1 and the sealing cover 3 are preferably made of PEEK material, which has extremely high mechanical rigidity and excellent chemical stability. The substantial advantage of using this material is that it can withstand long-term immersion and evaporation erosion from organic carbonates or highly corrosive aqueous battery electrolytes, preventing leakage from environmental media; furthermore, this material has excellent electrical insulation properties, capable of electrically insulating the internal micron-level working circuit from the external metal clamp as a whole, eliminating parasitic capacitance and stray current interference; simultaneously, it has a certain mechanical strength, ensuring that the mold does not undergo microscopic deformation when subjected to threaded fastening extrusion.

[0055] The base 1 is generally a stepped cylindrical structure, with a maximum outer diameter preferably ranging from 12 mm to 15 mm and an axial height ranging from 18 mm to 25 mm; the sealing cover 3 has a maximum outer diameter preferably ranging from 8 mm to 10 mm and an axial height ranging from 10 mm to 15 mm. The core purpose of controlling this external dimension configuration is to strictly control the dynamic rotation interference radius of the entire mold within 10 mm. This dimension can seamlessly adapt to the spatial limit boundary of commercial three-dimensional X-ray microscopes (such as CT imaging systems using a two-stage magnification architecture when performing long-distance high-resolution (RaaD) large working distance scanning), achieving sub-micron level spatial resolution imaging while ensuring sufficient safe rotation clearance (50 mm rotation radius space) between the objective scintillator and the sample shell, effectively avoiding mechanical interference.

[0056] The capillary shell 2 is made of a material capable of efficiently penetrating the X-ray radiation source emitted by the CT testing equipment. Preferably, the capillary shell 2 is made of one of polyimide (PI), thin-walled quartz glass, or beryllium metal.

[0057] The overall axial length is preferably between 15 mm and 25 mm, the outer diameter between 1.5 mm and 2.5 mm, and the inner diameter between 1.3 mm and 2.3 mm. The wall thickness of the core area of ​​the X-ray horizontal penetration window is strictly controlled within the range of 10 μm to 100 μm. The synergistic advantage of this specific material and thin-walled size distribution is that, according to the Beer-Lambert Law, the capillary shell 2 has low X-ray absorption characteristics. Under the irradiation of a broadband X-ray high-energy beam of 30 kV to 160 kV, this window area can provide an ultra-high photon transmittance of more than 85%, which fundamentally blocks the high attenuation effect and strong beam hardening artifacts caused by traditional thick-walled in-situ cells, and significantly improves the signal-to-noise ratio of weak-contrast component interface imaging.

[0058] The microelectrode assembly includes a first microelectrode 4 extending vertically upward from the center of the base 1, and a second microelectrode 5 extending vertically downward from the center of the sealing cover 3.

[0059] Preferably, the first microelectrode 4 and the second microelectrode 5 are made of any one or more combinations of tungsten (W), platinum (Pt), gold (Au), stainless steel, titanium (Ti), aluminum (Al), carbon fiber, or glassy carbon.

[0060] In this embodiment, both electrodes are preferably made of tungsten metal needles with extremely high axial bending stiffness and high conductivity. The outer diameter of the body needle rod of the two electrodes is preferably in the range of 0.5 mm to 1.0 mm.

[0061] The top of the first microelectrode 4 is processed into a tapered cone-shaped peak, and the radius of curvature of its tip is strictly controlled within the range of 1 μm to 10 μm, so as to accurately carry and support the micron-sized microparticles of the active material to be tested; the bottom of the second microelectrode 5 is processed into a flat bottom surface or a passivated ball head with a radius of curvature of 50 μm to 100 μm, which is used as a substrate for immobilizing the active metal of the counter electrode.

[0062] The tip of the first microelectrode 4 and the bottom end face of the second microelectrode 5 are strictly opposite to each other on the central axis in the space inside the capillary shell 2, and a gap is left between their axial tips. The micro-window space where the gap is located constitutes the battery micro-region reaction chamber.

[0063] Within this micro-reaction chamber, 1 μL to 3 μL of test electrolyte is quantitatively injected using a fine micro-syringe. The test electrolyte, relying on its own surface tension and capillary wetting force, bridges the tiny gap between the two electrode tips, thus constructing a minimally diaphragm-free liquid bridge conduction pathway without the need for traditional solid diaphragms such as glass fibers. The substantial advantage of this design is that it completely eliminates the interference of cluttered background contrast and absorption tomography introduced by solid diaphragm fibers in high-resolution CT reconstruction images, allowing for high-fidelity extraction of the material's internal pores and grain boundary defects.

[0064] like Figure 1 and Figure 2 As shown, a stainless steel metal pin 11 is vertically fixed to the bottom of the base 1, and the bottom of the first microelectrode 4 is rigidly electrically connected to the metal pin 11 inside the base 1. Preferably, the axial downward extension length of the metal pin 11 is 12 mm to 15 mm, and its outer diameter is rigidly set to a standard 3.2 mm. The advantage of this standardized size design is that it can be tightly mechanically engaged and locked with the micro-clamps in the rotating sample stage of a commercial three-dimensional X-ray microscope, greatly increasing the mechanical rigidity during rotation and effectively avoiding eccentric rotation vibration caused by chuck loosening or asynchrony.

[0065] To achieve truly unobstructed panoramic electrical signal extraction with zero mechanical torque during dynamic continuous rotation scanning, this invention designs a top-connected liquid alloy conduction circuit. For example... Figure 2 and Figure 3 As shown, the top of the sealing cover 3 is integrally formed with an upward-opening top-mounted liquid phase conductive groove 6. The top-mounted liquid phase conductive groove 6 has a miniature cup-shaped configuration, with a maximum outer diameter ranging from 6 mm to 10 mm and a groove depth ranging from 3 mm to 5 mm.

[0066] The annular reservoir is completely filled with a room-temperature liquid alloy electrode medium. Preferably, the room-temperature liquid alloy electrode medium is gallium indium tin alloy (GaInTan, preferably by weight: Ga 68.5%, In 21.5%, Sn 10%) or gallium indium alloy. Gallium indium tin alloy remains in a fluid state at room temperature and has extremely low vapor pressure and excellent conductivity. This preferred design utilizes the viscous resistance of the fluid to replace the dry friction of the solid, achieving zero mechanical torque and effectively eliminating focus drift and rotational oscillation artifacts caused by brush friction.

[0067] Regarding the electrical circuit, circuit one (working electrode circuit): a stainless steel metal pin 11 is integrally fixed at the bottom of the base 1.

[0068] The metal pin 11 extends downward axially for 12 mm to 15 mm, and its outer diameter is set to a standard 3.2 mm. The bottom of the first microelectrode 4 is rigidly connected to the metal pin 11, and the first electrical signal is derived from the bottom grounding circuit of the metal chuck of the rotating sample stage of a commercial X-ray CT device.

[0069] Circuit 2 (counter electrode circuit): The top of the second microelectrode 5 passes vertically upward along the central axis of the mold through the bottom wall of the sealing cover 3, and its top is directly exposed and extends into the top liquid phase conductive tank 6, forming a physical connection with the room temperature liquid alloy inside.

[0070] A fixed external electrode (with a tip diameter of 0.2 mm to 0.5 mm) is positioned directly above the mold inside the external CT equipment cabin. When the in-situ detection device rotates continuously and synchronously 360° with the rotating sample stage, the external electrode remains stationary relative to the CT equipment, and its tip is vertically suspended and immersed in the liquid alloy in the rotating top-mounted dynamic conductive tank 6, smoothly transmitting the second electrical signal through the frictionless liquid wetting interface.

[0071] Example 2

[0072] Based on the mold of Example 1, this embodiment of the invention provides a battery electrochemical reaction mold and a continuous rotation imaging method for in-situ X-ray CT observation, characterizing the spatiotemporal variation characteristics of the microcrack network in the material during the electrochemical process, such as... Figure 3 As shown, it includes the following steps:

[0073] S1. In-situ battery assembly:

[0074] In a glove box filled with argon gas (with water and oxygen content strictly below 0.01 ppm), using microtweezers and an optical microscope on a micro-nano manipulation platform, a small amount of conductive adhesive is applied to the tip of the tungsten needle of the first microelectrode 4 to precisely adhere active material particles; at the same time, a layer of elemental substances such as lithium, sodium, and potassium is loaded onto the bottom end face of the second microelectrode 5 as a counter electrode.

[0075] The first and second microelectrodes are axially aligned and installed into the mold, ensuring that the spatial coordinates of the working electrode tip particles coincide with the mold's rotation axis. The capillary shell 2 is then threaded tightly onto the base 1, and high-vacuum fluorosilicone sealant is applied to the threaded sealing surface to ensure long-term airtightness. Finally, 2 μL of electrolyte is injected through the micro-channel at the top of the sealing cap using a micro-injection pump, allowing it to form a liquid bridge between the two tungsten needle tips via surface tension. The sealing cap 3 is then locked, completing the precise assembly of the diaphragm-free micro-region in-situ half-cell.

[0076] S2. Device loading and electrical contact establishment:

[0077] Remove the assembled in-situ test mold from the glove box and vertically lock the standard 3.2 mm metal pin 11 at its bottom into the rotating sample stage chuck of the 3D X-ray microscope. Adjust the stationary electrode on the cantilever bracket inside the CT chamber so that its tip is immersed in the liquid gallium indium tin alloy tank of the top-mounted liquid phase conductive tank 6 to establish liquid immersion lubrication kinetic contact. Connect the metal pin 11 and the stationary electrode to the external electrochemical workstation connected outside the chamber.

[0078] S3. In-situ electrochemical and CT combined continuous testing:

[0079] An external electrochemical workstation applies an electrical signal to the battery, driving a continuous electrochemical reaction within the material in real time. Simultaneously with the activation of the electrochemical signal, a three-dimensional X-ray microscope is activated to perform continuous rotational testing. The rotating sample stage drives the entire in-situ test mold to perform a continuous 360° synchronous rotation. A long-range high-resolution (RaaD) imaging optical path is configured, with the distance from the sample to the light source and the propagation distance from the sample to the flat panel detector precisely set to 250 mm to obtain optimal Fresnel diffraction boundary enhancement signals.

[0080] The X-ray source was turned on, and the source voltage was set to 60 kV and the power to 10 W. The flat panel detector, in conjunction with the uniform rotation of the sample, performed uninterrupted, continuous "fly-scan" projection data stream acquisition. During the entire cycle before the charge-discharge cutoff, one frame was sampled every 0.5° angular velocity, continuously and losslessly capturing the in-situ dynamic two-dimensional projection data stream.

[0081] S4. Dynamic geometric center correction:

[0082] The continuously acquired 2D projection data stream is imported into a high-performance parallel graphics workstation. A geometric correction algorithm is used to automatically filter and extract opposing projection image pairs with a relative rotation angle of precisely 180°. The algorithm automatically identifies the outer edge of the capillary shell 2 in the opposing left and right images using computer vision operators and calculates its spatial boundary geometric centroid trajectory. The least squares method is used to fit this trajectory into a spatial sine curve, thereby accurately solving for the micro-amplitude mechanical oscillation and eccentric axis drift caused by the continuous rotation throughout the entire cycle. The algorithm also performs corresponding translation and rotation compensation on the global pixel coordinates of each frame of the projection image.

[0083] S5. Spatiotemporal Joint Blur Suppression and Phase Contrast Reconstruction:

[0084] Because the active material undergoes real-time phase transition lattice contraction and volumetric rheological evolution during electrochemical processes, its morphology remains in a state of continuous non-rigid motion within the CT scanning time window. Traditional static FDK filtering back projection reconstruction algorithms can lead to severe fringe motion artifacts in the reconstructed image. This embodiment constructs a method that includes a time weighting factor and a first-order forward difference of the time axis. The spatiotemporal joint iterative reconstruction model with norm regularization constraints is designed for the target time node. The objective function for reconstructing the three-dimensional density field is expressed as:

[0085]

[0086] In the formula, For the forward difference operator along the time axis, This is a volumetric data sequence showing the evolution of the three-dimensional shape to be reconstructed over time. The system projection matrix, This is a geometrically corrected two-dimensional projection data stream based on actual measurements. The time difference regularization parameter is used. This reconstruction algorithm utilizes the physical prior characteristics of local spatial sparsity of electrochemical reactions and lattice thermodynamic micro-damage within adjacent extremely short time windows to automatically identify and filter out false fringe trails and time ghosting caused by rotational motion and rheological interweaving.

[0087] The Fresnel diffraction fringe signal captured at a propagation distance of 250 mm was synchronously imported. The high-contrast phase shift field of single-particle material was decoupled using a phase recovery operator based on Fast Fourier Transform (FFT). An edge enhancement operator was introduced in the three-dimensional reconstruction loop. Finally, the high-contrast, high-fidelity three-dimensional structure data sequence of light element phase interface under different state of charge (SOC) nodes throughout the entire cycle was reconstructed and output.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A battery electrochemical reaction mold for in-situ X-ray CT observation, characterized in that, include: Base (1), with a metal pin (11) fixed at its bottom; The capillary shell (2) is sealed and connected above the base (1); A sealing cover (3) is sealed to the top of the capillary shell (2). A top liquid phase conductive groove (6) is provided on the top of the sealing cover (3). The top liquid phase conductive groove (6) is filled with a room temperature liquid alloy electrode medium, which is used to form a liquid immersion lubricating kinetic contact with the external electrode needle located above the mold and kept stationary. The base (1) and the sealing cover (3) are provided with microelectrode assemblies.

2. The battery electrochemical reaction mold for in-situ X-ray CT observation according to claim 1, characterized in that, The microelectrode assembly includes a first microelectrode (4) extending upward from the interior of the base (1) and a second microelectrode (5) extending downward from the interior of the sealing cover (3). The metal pin (11) is electrically connected to the first microelectrode (4); the top of the second microelectrode (5) extends vertically upward along the central axis of the mold through the bottom wall of the sealing cover (3), and its top is directly exposed and extends into the interior of the top liquid phase conductive tank (6).

3. The battery electrochemical reaction mold for in-situ X-ray CT observation according to claim 2, characterized in that, The tip of the first microelectrode (4) and the bottom of the second microelectrode (5) define a micro-reaction chamber within the capillary shell (2), and a gap is left between the tips of the two electrodes. The top of the first microelectrode (4) carries a group of micro particles of the active substance to be tested, and the gap is filled with a small amount of test electrolyte. The test electrolyte forms a membrane-free liquid bridge conduction path by relying on surface tension. The tip curvature radius of the first microelectrode (4) is 1 μm to 10 μm, and the bottom end of the second microelectrode (5) is a flat end face or a passivated ball head with a curvature radius of 50 μm to 100 μm.

4. The battery electrochemical reaction mold for in-situ X-ray CT observation according to claim 1, characterized in that, The capillary shell (2) is airtightly encapsulated between the base (1) and the sealing cover (3) by a built-in corrosion-resistant O-ring and a threaded pressing structure. The capillary shell (2) is made of polyimide, quartz or beryllium, and the wall thickness of the corresponding core area of ​​the window ranges from 10 μm to 100 μm. The total axial length of the capillary shell (2) ranges from 15 mm to 25 mm, the outer diameter ranges from 1.5 mm to 2.5 mm, and the inner diameter ranges from 1.3 mm to 2.3 mm.

5. The battery electrochemical reaction mold for in-situ X-ray CT observation according to claim 2, characterized in that, The room-temperature liquid alloy electrode medium is a gallium indium tin alloy or a gallium indium alloy; The base (1) and the sealing cover (3) are each made of one of the following materials: polyetheretherketone, polytetrafluoroethylene, polyimide, or electrolyte-resistant resin. The maximum outer diameter of the base (1) is 12 mm to 15 mm and the axial height is 18 mm to 25 mm; the maximum outer diameter of the sealing cover (3) is 8 mm to 10 mm and the axial height is 10 mm to 15 mm. The outer diameter of the metal pin (11) is 3.2 mm, and the axial downward extension length is 12 mm to 15 mm. The materials of the first microelectrode (4) and the second microelectrode (5) are each independently tungsten, platinum, gold, stainless steel, titanium, aluminum, carbon fiber or glassy carbon, any one or more combinations thereof.

6. A method for in-situ electrochemical continuous rotational imaging of a battery based on the mold described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Battery assembly: Under inert atmosphere conditions, fix the active material to be tested to the tip of the first microelectrode (4) and adjust it to the center of rotation of the mold; load the active metal of the counter electrode in the micro-area at the bottom of the second microelectrode (5); seal the capillary shell (2) with the base (1) and the sealing cover (3) in an airtight manner, and inject electrolyte to form a liquid bridge. S2, Device loading: Fix the metal pin (11) inside the rotating sample stage of the CT equipment; immerse the tip of the external stationary electrode into the room temperature liquid alloy electrode medium in the top liquid phase conductive tank (6); S3, In-situ electrochemical and CT combined test: Apply charge and discharge signal, start CT test at the same time, the self-rotating sample stage drive device rotates continuously, X-rays penetrate the capillary shell (2) horizontally, and the detector continuously collects projection data; S4. Dynamic geometric center correction: Extract projection data pairs, calculate the geometric centroid trajectory and perform spatial coordinate translation compensation; S5. Spatiotemporal Joint Blur Suppression and Phase Contrast Reconstruction: A spatiotemporal joint iterative reconstruction model is constructed, which includes a time weighting factor and a first-order forward difference L1 norm term of the time axis as regularization constraints, to suppress motion blur caused by dynamic evolution of morphology; at the same time, Fresnel diffraction signals at a preset propagation distance are collected to decouple the phase shift signal, and an edge enhancement operator is introduced in the reconstruction to reconstruct the three-dimensional structural data of the micro-particle group inside the battery.

7. The battery in-situ electrochemical continuous rotation imaging method according to claim 6, characterized in that, In step S4, the opposing projection image pairs with a relative rotation angle of 180° are extracted from the projection data stream, the spatial boundary geometric centroid trajectory of the outer edge of the capillary shell (2) is identified, the trajectory is fitted into a spatial sine curve using the least squares method, the eccentric axis drift is solved in reverse, and translation and rotation compensation are implemented.

8. The battery in-situ electrochemical continuous rotation imaging method according to claim 6, characterized in that, In step S5, the time difference regularization constraint term is expressed as follows: ,in For the forward difference operator along the time axis, This is a volumetric data sequence showing the evolution of the three-dimensional shape to be reconstructed over time. This is the regularization parameter.

9. The battery in-situ electrochemical continuous rotation imaging method according to claim 6, characterized in that, In step S5, the preset propagation distance is 250 mm.

10. The battery in-situ electrochemical continuous rotation imaging method according to claim 6, characterized in that, In step S5, the objective function of the spatiotemporal joint iterative reconstruction model is: In the formula, For the forward difference operator along the time axis, This is a volumetric data sequence showing the evolution of the three-dimensional shape to be reconstructed over time. The system projection matrix, This is a geometrically corrected two-dimensional projection data stream based on actual measurements. This is the time difference regularization parameter.

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