Preparation method and characterization method of CT imaging sample for polymer electrolyte membrane

Abstract

The invention provides a preparation method and a characterization method of a CT imaging sample for a polymer electrolyte membrane, and belongs to the field of batteries. The method comprises the following steps: in an inert gas atmosphere, dropwise adding a photosensitive oligomer to the surface of a to-be-detected sample, so that the photosensitive oligomer wraps at least part of the surface of the to-be-detected sample to obtain a first sealant; the to-be-detected sample is a polymer solid electrolyte membrane and lithium metal; a thin rod-shaped fixing piece is arranged at the tail end of the first sealing object, and a second sealing object is obtained; and carrying out ultraviolet light curing on the second sealing object to obtain the CT imaging sample. The flexible polymer electrolyte membrane and the lithium metal are subjected to sealed sample preparation by adopting the photosensitive oligomer, so that extra mechanical and chemical stability is provided for a sample to be detected. And the position of the battery sample in the CT imaging device is fixed by adopting the thin rod-shaped fixing piece, so that the limit resolution of the instrument is exerted to the maximum extent. Therefore, a novel CT imaging sample preparation method suitable for the polymer solid electrolyte membrane is provided.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to methods for preparing and characterizing CT imaging samples for polymer electrolyte membranes. Background Technology

[0002] Advanced battery technology is a key support for achieving China's electric vehicle strategy, with high energy density, long lifespan, and high safety being crucial future research and development goals. Currently commercially available traditional lithium-ion batteries (liquid organic electrolyte, graphite anode) pose safety risks due to flammability and explosion, and have limited energy density (~350 Wh / kg). In contrast, solid-state batteries, using non-flammable solid electrolytes and lithium metal anodes, offer higher energy density and safety, representing the next generation of advanced battery systems. Unlike traditional batteries, all-solid-state batteries are complex multiphase systems composed of solid particles, with all internal interfaces being solid-solid interfaces. During charging and discharging, electrochemical reactions (chemical fields) cause changes in electrode volume (strain fields), resulting in localized stress accumulation (stress fields). This leads to deterioration of solid-solid interface contact and solid particle fracture, resulting in increased battery resistance, rapid capacity decay, and rate performance degradation. Therefore, systematically studying the multi-field coupling effects within solid-state batteries is crucial for clarifying the failure and runaway mechanisms of all-solid-state batteries.

[0003] X-ray computed tomography (CT) is a non-destructive imaging technique that, in addition to its common application in biomedicine, has now been extended to characterizing the static and dynamic information of key components such as semiconductor devices and batteries. It captures the electrochemical behavior and multi-scale structural evolution of materials under operating conditions, thus closely correlating various morphological parameters (particle size, pore distribution, crack propagation, etc.) at the micro, meso, and macro scales, providing assistance in understanding failure mechanisms and designing and developing new materials. Inorganic ceramic solid electrolytes, due to their high mechanical strength, can be placed in various small-sized battery molds through powder compression for high-resolution X-ray CT characterization. However, flexible polymer electrolytes are often difficult to self-support and are easily bent in small battery molds, making sample preparation for CT characterization challenging. Summary of the Invention

[0004] This application provides a method for preparing and characterizing CT imaging samples for polymer electrolyte membranes to solve the following technical problem: providing a new sample preparation method suitable for CT imaging of polymer solid electrolyte membranes.

[0005] In a first aspect, embodiments of this application provide a method for preparing a CT imaging sample for a polymer electrolyte membrane, the method comprising: In an inert gas atmosphere, a photosensitive oligomer is dropped onto the surface of the sample to be tested, so that the photosensitive oligomer coats at least a portion of the surface of the sample to be tested, thereby obtaining a first sealant; the sample to be tested is a polymer solid electrolyte membrane and lithium metal; A thin rod-shaped fixing member is placed at the tail end of the first seal to obtain a second seal containing the thin rod-shaped fixing member; and The second sealant was cured with ultraviolet light to obtain a CT imaging sample containing a thin rod-shaped fixator.

[0006] Optionally, the mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane is (0.5-3):1.

[0007] Optionally, the mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane is (1-2):1.

[0008] Optionally, the photosensitive oligomer includes: polyurethane acrylate.

[0009] Optionally, the polymer solid electrolyte membrane is a flexible polymer composite solid electrolyte membrane.

[0010] Optionally, the UV lamp power for UV curing is 2W to 5W, and the UV lamp irradiation time for UV curing is 5s to 15s.

[0011] Optionally, the UV lamp for UV curing has a power of 3.5W, and the UV lamp irradiation time for UV curing is 10s.

[0012] Optionally, the thin rod-shaped fastener includes: a hard metal rod, a metal wire, and a pin.

[0013] Secondly, this application provides a method for characterizing CT imaging samples of polymer electrolyte membranes, the method comprising: The CT imaging sample obtained in any one embodiment of the first aspect is placed vertically in the clamp of the CT imaging device; the clamp has an inner cavity for accommodating the thin rod-shaped fixation member; The fixture containing the CT imaging sample is inserted into the sample stage of the CT imaging device to irradiate the CT imaging sample with X-rays and obtain a CT image of the CT imaging sample.

[0014] Optionally, the energy of the X-ray irradiation is 30% to 35% of the critical value of 100% transmittance energy.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for preparing a CT imaging sample for a polymer electrolyte membrane. The method includes: in an inert gas atmosphere, dropwise adding a photosensitive oligomer onto the surface of a sample to be tested, such that the photosensitive oligomer coats at least a portion of the surface of the sample to be tested, to obtain a first sealant; the sample to be tested is a polymer solid electrolyte membrane and lithium metal; placing a thin rod-shaped fixing member at the tail end of the first sealant to obtain a second sealant; and curing the second sealant with ultraviolet light to obtain a CT imaging sample; the thin rod-shaped fixing member is used to fix the CT imaging sample in a CT imaging device. Flexible polymer composite solid electrolyte membranes are generally difficult to self-support and are easily bent in small battery molds, making CT characterization sample preparation difficult. This application employs a photosensitive oligomer to seal and prepare a flexible polymer electrolyte membrane and lithium metal. On one hand, the photosensitive oligomer material itself does not chemically react with the polymer electrolyte membrane and lithium metal. On the other hand, after curing, the photosensitive oligomer forms a stable and transparent sealing layer, providing additional mechanical and chemical stability to the sample. Simultaneously, the cured photosensitive oligomer has high light transmittance, facilitating clear observation of the internal structure and interface evolution of the polymer solid electrolyte membrane in subsequent CT imaging. Furthermore, a specialized thin rod-shaped fixture is used to fix the battery sample in the CT imaging device, ensuring that high light transmittance is maintained while maximizing the instrument's ultimate resolution. This provides a novel sample preparation method suitable for CT imaging of polymer solid electrolyte membranes. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for preparing a CT imaging sample using a polymer electrolyte membrane, provided as an embodiment of this application; Figure 2 A flowchart illustrating a characterization method for CT imaging samples of polymer electrolyte membranes provided in this application embodiment; Figure 3 This is a schematic diagram of a method for preparing a CT imaging sample for a polymer electrolyte membrane, as provided in Embodiment 1 of this application. Figure 4This is a schematic diagram of the X-ray CT imaging device provided in Embodiment 1 of this application; Figure 5 This is a physical image of the X-ray CT imaging device provided in Embodiment 1 of this application; Figure 6 The graph showing the relationship between transmittance and photon energy of the sample to be tested provided in Example 1 of this application; Figure 7 A two-dimensional cross-sectional X-ray CT image of a failed lithium metal battery based on a polymer electrolyte membrane, provided in Embodiment 1 of this application; Figure 8 The X-ray CT imaging three-dimensional reconstruction image of a failed lithium metal battery based on a polymer electrolyte membrane provided in Embodiment 1 of this application; Figure 9 This is a two-dimensional cross-sectional view of a millimeter-cell battery device based on a polymer electrolyte membrane and X-ray CT imaging provided in Comparative Example 1 of this application; Figure label: 1-Sample to be tested, 2-UV curing sealant, 3-Dropper, 4-UV lamp, 5-Fine rod-shaped fixture, 6-X-ray source, 7-Detector, 8-X-ray, 9-Clamp, 10-Sample stage. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0021] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts representation" such as parts by weight or parts by mass indicates the proportional relationship between components. In the proportional relationships discussed in this article, parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, while the proportion figure should be understood as the second term. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion figure in the proportion in the order of description, i.e., the mass of substance A : the mass of substance B : the mass of substance C = 1:2:3.

[0022] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0023] Figure 1 This is a schematic flowchart illustrating a method for preparing a CT imaging sample using a polymer electrolyte membrane, as provided in an embodiment of this application.

[0024] like Figure 1 As shown, this application provides a method for preparing a CT imaging sample for a polymer electrolyte membrane, the method comprising: S101. In an inert gas atmosphere, a photosensitive oligomer is dropped onto the surface of the sample to be tested, so that the photosensitive oligomer coats at least a portion of the surface of the sample to be tested, thereby obtaining a first sealant; the sample to be tested is a polymer solid electrolyte membrane and lithium metal. After the photosensitive oligomer is dropped onto the surface of the polymer sample, it can encapsulate and seal at least a portion of the sample's surface. Upon curing, the photosensitive oligomer forms a stable and transparent sealing layer, providing additional mechanical and chemical stability to the sample. Simultaneously, the cured photosensitive oligomer exhibits high light transmittance, which facilitates clear observation of the internal structure and interface evolution of the polymer solid electrolyte membrane in subsequent CT imaging.

[0025] In some embodiments, the mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane is (0.5–3):1.

[0026] By limiting the mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane to within the range of (0.5–3):1, the photosensitive oligomer can form a coating layer of appropriate thickness on the surface of the sample to be tested. This coating layer is neither too thick, resulting in an excessively large overall sample size, nor too thin, failing to provide sufficient sealing. Simultaneously, the appropriate coating layer thickness helps enhance the mechanical strength and chemical stability of the sample. Furthermore, the curing speed of the photosensitive oligomer is moderate, neither too fast, leading to uneven curing, nor too slow, prolonging the preparation cycle. For example, the mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, etc.

[0027] In some embodiments, the mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane is (1-2):1.

[0028] The mass ratio of the photosensitive oligomer to the polymer solid electrolyte membrane is defined as (1-2):1. The cured photosensitive oligomer has high transparency and good mechanical strength, which can further meet the requirements of CT imaging for sample sealing and stability.

[0029] In some embodiments, the photosensitive oligomer comprises polyurethane acrylate.

[0030] It should be noted that polyurethane acrylates are typically produced by reacting polymers with terminal hydroxyl groups, such as macromolecular diols (or polyols), with diisocyanates to obtain isocyanate-terminated oligomers, which are then reacted with hydroxyethyl acrylates. The terminal hydroxyl polymers can be polyesters, polyethers, polyacrylates, or polyurethanes, etc., and the diisocyanates can be selected from different aromatic or aliphatic diisocyanates depending on the application requirements.

[0031] The main reasons for choosing polyurethane acrylate (PUA) as a UV-cured sealing material are as follows: (1) Polyurethane acrylate can undergo rapid free radical polymerization under ultraviolet light irradiation, achieving a rapid transformation from liquid to solid. This characteristic makes it very suitable as a fast-curing sealing material. The cured polyurethane acrylate has high transparency and good mechanical strength, which can meet the requirements of CT imaging for sample sealing and stability.

[0032] (2) Polyurethane acrylates have good compatibility with a variety of materials, including commercial plastic products, polymer electrolytes, and lithium metal. This means that polyurethane acrylates will not chemically react with these materials during the preparation process, thus ensuring the integrity of the sample and the stability of its performance. At the same time, this compatibility also helps to reduce the complexity and cost of the preparation process.

[0033] (3) The precursor of polyurethane acrylate is a gel-like liquid at room temperature, which makes it easy to store and transport. In addition, due to its liquid properties, polyurethane acrylate can be easily applied to the sample to be tested by means of drop addition, thereby simplifying the preparation process.

[0034] (4) Cured polyurethane acrylate has high light transmittance, which makes it very suitable as a transparent sealing material in CT imaging. High light transmittance helps to clearly observe the internal structure and evolution process of the sample during CT imaging, thereby improving the accuracy and resolution of imaging.

[0035] (5) Polyurethane acrylate has a certain degree of thermal stability, and can maintain the stability of its performance and structure within a certain temperature range. This characteristic allows it to be used in various environments, including high or low temperature conditions in CT imaging devices.

[0036] In summary, the selection of polyurethane acrylate as a UV-initiated curing sealing material is based on a comprehensive consideration of its excellent curing performance, good compatibility, ease of storage and handling, high light transmittance, thermal stability, and broad application prospects. These characteristics make polyurethane acrylate an ideal choice for preparing CT imaging samples suitable for polymer solid electrolytes.

[0037] In some embodiments, the polymer solid electrolyte membrane is a flexible polymer composite solid electrolyte membrane.

[0038] Flexible polymer composite solid electrolyte membranes are often difficult to self-support and are easily bent in small battery molds, making CT characterization sample preparation difficult. Meanwhile, observation of the electrolyte-electrode interface requires high spatial resolution. The UV-cured sample of this invention enables controllable sealing of small-sized samples. A specialized mold (a professional component provided with Zeiss CT equipment) is used to fix the position of the battery sample, maximizing the instrument's maximum resolution while ensuring transmittance, allowing for X-ray CT imaging characterization and monitoring of the battery's internal structure and interface evolution before and after cycling.

[0039] S102. Place the thin rod-shaped fixing member at the tail end of the first seal to obtain a second seal containing the thin rod-shaped fixing member; and In some embodiments, the thin rod-shaped fastener includes: a hard metal rod, a metal wire, and a pin.

[0040] The sealing process is completed in an inert atmosphere protection device, which further prevents the sample from reacting with oxygen, moisture, etc. in the air, thereby maintaining the original properties and structure of the sample.

[0041] After sealing, the sealed sample with the pin inserted is placed in a specialized fixture and locked vertically. The fixture is designed to ensure the stability and accuracy of the sample during imaging. The fixture is then vertically inserted into the sample stage for CT imaging.

[0042] S103. The second sealant is cured with ultraviolet light to obtain a CT imaging sample containing a thin rod-shaped fixation member.

[0043] The thin rod-shaped fixing member is used to fix the CT imaging sample in the CT imaging device. Under ultraviolet light irradiation, the photosensitive oligomer undergoes a free radical cross-linking polymerization reaction, transforming from a liquid state to a solid state, forming a stable and transparent sealing material. This step is a critical step in the sample preparation process, directly affecting the performance of the sample and the quality of CT imaging. Simultaneously, the cured sealing material has high light transmittance and good mechanical strength, which helps to improve resolution and clarity in CT imaging, thereby enabling more accurate observation of the internal structure and interface evolution of the polymer solid electrolyte membrane.

[0044] In some embodiments, the UV lamp power for UV curing is 2W to 5W, and the UV lamp irradiation time for UV curing is 5s to 15s.

[0045] With a power range of 2W to 5W, the UV lamp provides sufficient energy to trigger the polymerization reaction of the photosensitive oligomer. Power below 2W results in incomplete curing, while power above 5W leads to over-curing or sample damage. An irradiation time of 5s to 15s ensures that the photosensitive oligomer fully absorbs UV energy and completes the polymerization reaction. A time shorter than 5s results in insufficient curing, while a time longer than 15s triggers unnecessary thermal effects or photochemical reactions, affecting sample performance. For example, the UV lamp power for UV curing can be 2W, 2.5W, 3W, 3.5W, 4W, 4.5W, 5W, etc., and the irradiation time can be 5s, 7s, 9s, 10s, 12s, 14s, 15s, etc.

[0046] In some embodiments, the UV lamp for UV curing has a power of 3.5W, and the UV lamp irradiation time for UV curing is 10s.

[0047] The UV lamp power for UV curing is limited to 3.5W, and the UV lamp irradiation time for UV curing is 10s, which can further initiate the polymer free radical cross-linking polymerization reaction to construct a sealing material with both good mechanical strength and chemical stability.

[0048] Figure 2 This is a schematic flowchart illustrating a characterization method for CT imaging samples of polymer electrolyte membranes provided in an embodiment of this application.

[0049] like Figure 2 As shown, this application provides a method for characterizing CT imaging samples of polymer electrolyte membranes, the method comprising: S201. The CT imaging sample obtained in any of the above embodiments is placed vertically in the fixture of the CT imaging device; the fixture has an inner cavity for accommodating the thin rod-shaped fixation member; S202. The fixture containing the CT imaging sample is inserted into the sample stage of the CT imaging device to irradiate the CT imaging sample with X-rays and obtain a CT image of the CT imaging sample.

[0050] It should be noted that the rotatable and translatable sample stage is located between the horizontally emitting X-ray source and the detector, and the CT imaging sample is adjusted to be located in the irradiation area for testing.

[0051] In some embodiments, the energy of the X-ray irradiation is 30% to 35% of the critical value of 100% transmittance energy.

[0052] Because the contrast of lightweight materials such as carbon and lithium is almost invisible under high-energy X-ray irradiation, the X-ray irradiation energy in this embodiment is limited to 30% to 35% of the critical value for 100% transmittance. The X-ray energy must be high enough to penetrate the sealing material, yet low enough to produce good contrast and differentiation among the components in the sample. For example, the X-ray irradiation energy can be 30%, 31%, 32%, 33%, 34%, 35%, etc., of the critical value for 100% transmittance.

[0053] This method is a sample preparation and characterization method suitable for CT imaging of polymer solid electrolytes. Its advantages can be summarized in detail as follows: Advantages of the sample preparation method: (1) High-efficiency sealing and curing: By dropping a photosensitive oligomer onto the surface of the sample to be tested, a stable and transparent coating can be quickly formed, providing additional mechanical and chemical stability for small-sized samples. At the same time, the UV curing process is rapid and can be completed in a short time (5s to 15s). The cured photosensitive oligomer has high transparency and good mechanical strength, which meets the requirements of CT imaging for sample sealing and stability.

[0054] (2) Precise control of coating thickness: By limiting the mass ratio of photosensitive oligomer to polymer solid electrolyte membrane to (0.5-3):1, a coating layer of appropriate thickness can be formed, which is neither too thick to cause the overall size of the sample to be too large, nor too thin to provide sufficient sealing effect.

[0055] (3) Wide material compatibility: As a UV-cured sealing material, polyurethane acrylate has good compatibility with a variety of materials (including commercial plastic products, polymer electrolytes and lithium metal, etc.), ensuring the integrity of the sample and the stability of its performance.

[0056] (4) Easy to store and handle: The precursor of polyurethane acrylate is a gel-like liquid at room temperature, which is convenient for storage and transportation. At the same time, its liquid properties make it easy to apply to the sample to be tested by means of dripping, which simplifies the preparation process.

[0057] (5) High adaptability: This method is particularly suitable for samples that are difficult to support themselves, such as flexible polymer composite solid electrolyte membranes, and can effectively seal and fix them, which is convenient for CT imaging characterization.

[0058] Advantages of characterization methods: (1) High-resolution imaging: The battery sample is fixed in position using a special mold and fixture to maximize the instrument's resolution while ensuring light transmittance, and then X-ray CT imaging characterization is performed. At the same time, high-resolution CT imaging can clearly observe the internal structure and interface evolution of the polymer solid electrolyte membrane, improving the accuracy and resolution of the imaging.

[0059] (2) Flexible sample adjustment: The position and orientation of the sample to be tested can be easily adjusted by using thin rod-shaped fixing parts (such as hard metal rods, metal wires and pins) to adapt to the requirements of CT imaging devices.

[0060] (3) Optimized X-ray energy: The energy of X-ray irradiation is limited to 30% to 35% of the critical value of 100% transmittance energy, which can both penetrate the sealing material and produce good contrast and differentiation of each component in the sample.

[0061] (4) Non-destructive testing: CT imaging technology is a non-destructive testing method that can obtain information about the internal structure of a sample without damaging it.

[0062] In summary, this method combines efficient sample preparation techniques with high-resolution characterization methods, providing a reliable and effective solution for CT imaging of polymer solid electrolytes. This method not only improves the efficiency and accuracy of sample preparation but also optimizes the resolution and contrast of CT imaging, providing strong support for in-depth research into the internal structure and properties of polymer solid electrolytes.

[0063] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0064] Example 1 Figure 3 This is a schematic diagram of a method for preparing a CT imaging sample for a polymer electrolyte membrane, as provided in Embodiment 1 of this application.

[0065] like Figure 3As shown, this embodiment provides a method for preparing a cellulose / zirconia polymer composite solid electrolyte membrane and a CT sample of a lithium metal battery sensitive to humid air. In this embodiment, polyurethane acrylate, which is stable to the lithium metal anode, is used as a photosensitive oligomer to prepare a UV-curable sealing material 2. In a high-purity argon atmosphere glove box, the sealing material precursor is dropped onto the surface of the sample to be tested 1 using a dropper 3 to completely wrap it. At the same time, a pin 5 is placed at the tail end of the sample to be tested 1 to seal it together. Then, the entire sealing material is irradiated with a UV lamp 4 and then left to cure.

[0066] Among them, sample 1 is a lithium-composite electrolyte membrane-lithium symmetric battery. The mass ratio of UV-cured sealing material to polymer solid electrolyte membrane is 1.5:1. The irradiation power of the UV lamp is 3.5W and the irradiation time is 10s.

[0067] Figure 4 This is a schematic diagram of the X-ray CT imaging device provided in Embodiment 1 of this application; Figure 5 This is a physical image of the X-ray CT imaging device provided in Embodiment 1 of this application.

[0068] like Figure 4 and Figure 5 As shown, this embodiment provides an X-ray CT imaging characterization method, and the relevant components of the CT imaging device include: X-ray source 6, which emits horizontal X-rays 8, is horizontally movable; Detector 7 is horizontally aligned with the X-ray (8) emitting end and is horizontally movable; The sample stage 10 is placed on an electrically driven rotatable base and is located between the X-ray source (6) and the detector (7); When performing in-situ imaging tests, the fixture 9 is inserted upright on the sample stage for characterization, so that the sample (1) is in the irradiation area of ​​the X-ray source (6).

[0069] The specific CT imaging characterization method includes: the solidified sample (1) together with the pin (5) is vertically placed in a special fixture (9) and locked, and then a rotatable and translatable sample stage (10) is inserted. During the test, the sample stage (10) is located between the X-ray source (6) that can emit X-rays (8) horizontally and the detector (7), and the sample is adjusted to be located in the irradiation area for testing.

[0070] Figure 6 This is a graph showing the relationship between the transmittance and photon energy of the sample to be tested provided in Example 1 of this application.

[0071] like Figure 6As shown, the contrast of lightweight materials such as carbon and lithium is almost invisible under high-energy X-ray irradiation. Therefore, the X-ray energy selected in this invention must be high enough to penetrate the sealing material, yet low enough to produce good contrast and differentiation of the components in the sample. The relationship between the transmittance of the cellulose-based polymer electrolyte membrane and photon energy can be calculated using a formula to obtain a curve, as shown below. Figure 4 As shown. Generally speaking, the energy value used in actual operation is about 30% to 35% of the critical value of 100% transmittance energy, and this standard is used as the basis for determining the further energy value.

[0072] Figure 7 This is a two-dimensional cross-sectional X-ray CT image of a failed lithium metal battery based on a polymer electrolyte membrane, provided in Embodiment 1 of this application.

[0073] Depend on Figure 7 It can be seen that the strip-like structure of the polymer electrolyte membrane, as well as the contrast and pore distribution of lithium metal, can be clearly distinguished through the cross-sectional CT imaging. The microscopic morphological features of the electrolyte membrane cracking in the failed sample can be clearly seen.

[0074] Figure 8 This is a three-dimensional reconstruction image of a failed lithium metal battery based on a polymer electrolyte membrane provided in Embodiment 1 of this application using X-ray CT imaging.

[0075] Depend on Figure 8 It can be seen that after three-dimensional reconstruction, the porosity of the sample, the deposition morphology of lithium metal, and the spatial distribution of cracks can be further quantitatively analyzed.

[0076] Comparative Example 1 The millimeter-cell battery containing a polymer electrolyte membrane was subjected to in-situ CT testing, and the results are as follows: Figure 9 As shown.

[0077] Figure 9 This is a two-dimensional cross-sectional view of a millimeter-cell battery device based on a polymer electrolyte membrane and X-ray CT imaging, provided in Comparative Example 1 of this application.

[0078] Depend on Figure 9 It can be seen that the flexible polymer electrolyte membrane is subjected to pressure, bending and extrusion in a battery mold with an inner diameter of 1 mm, making sample preparation difficult and the resolution extremely limited.

[0079] Furthermore, one or more technical solutions in the embodiments of this application have at least the following technical effects or advantages: In this embodiment, flexible polymer composite solid electrolyte membranes are typically difficult to self-support and are easily bent in small battery molds, making CT characterization sample preparation challenging. Furthermore, observation of the electrolyte-electrode interface requires high spatial resolution. The UV-cured sample of this invention enables controllable sealing of small-sized samples. A specialized mold fixes the battery sample position, maximizing the instrument's maximum resolution while ensuring transmittance, allowing for X-ray CT imaging characterization and monitoring of the battery's internal structure and interface evolution before and after cycling.

[0080] In this embodiment, the UV-cured sealing material is transparent after curing, the precursor is easy to store, does not react with commercial plastic products, is a gel-like liquid at room temperature, and does not chemically react with polymer electrolytes, lithium metal, etc. in the sample, and has a certain degree of thermal stability.

[0081] In this embodiment, a UV-curable material is used to seal the flexible polymer electrolyte membrane and lithium metal for sample preparation. This material itself does not chemically react with the polymer electrolyte membrane or lithium metal. The entire sample preparation process is completed in an inert atmosphere protection device. This method facilitates the preparation of small-sized CT imaging samples and ensures sufficient transmittance and imaging resolution for testing. The sealed sample is fixed with pins and vertically locked in a fixture. During imaging characterization, the fixture is upright with the sample stage inserted, and the entire device is positioned between the X-ray source and the detector, with horizontal movement adjusting the distance.

[0082] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a CT imaging sample of a polymer solid-state electrolyte, the method comprising: dropping a photosensitive oligomer onto a surface of a sample to be measured in an inert gas atmosphere, so that the photosensitive oligomer is wrapped around at least part of the surface of the sample to be measured, to obtain a first seal; the sample to be measured is a polymer solid-state electrolyte film and lithium metal; placing a thin rod-shaped fixing member at the tail end of the first seal to obtain a second seal containing the thin rod-shaped fixing member; and subjecting the second seal to ultraviolet light curing to obtain a CT imaging sample containing the thin rod-shaped fixing member.

2. The method of claim 1, wherein, The mass ratio of the photosensitive oligomer to the polymer solid-state electrolyte film is (0.5-3):

1.

3. The method of claim 2, wherein, The mass ratio of the photosensitive oligomer to the polymer solid-state electrolyte film is (1-2):

1.

4. The method of claim 3, wherein, The photosensitive oligomer comprises polyurethane acrylate.

5. The method of claim 3, wherein, The polymer solid-state electrolyte film is a flexible polymer composite solid-state electrolyte film.

6. The method of claim 1, wherein, The ultraviolet light curing is performed using an ultraviolet lamp with a power of 2-5 W, and the ultraviolet light curing is performed for 5-15 s.

7. The method of claim 6, wherein, The ultraviolet light curing is performed using an ultraviolet lamp with a power of 3.5 W, and the ultraviolet light curing is performed for 10 s.

8. The method of claim 1, wherein, The thin rod-shaped fixing member comprises a hard metal rod, a metal wire, and a large needle. 9.A method for characterizing a CT imaging sample of a polymer electrolyte film, the method comprising: vertically placing the CT imaging sample obtained by any one of claims 1-8 in a clamp of a CT imaging device; the clamp has an inner cavity accommodating the thin rod-shaped fixing member; inserting the clamp containing the CT imaging sample into a sample stage of the CT imaging device to perform X-ray irradiation on the CT imaging sample, to obtain a CT imaging image of the CT imaging sample.

10. The method of claim 9, wherein, The energy of the X-ray irradiation is 30-35% of the critical value of the percentage of light transmission energy.

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