Scanning electron microscope sample section and preparation method and application thereof

Abstract

The invention relates to a scanning electron microscope sample section and a preparation method and application thereof. The preparation method comprises the following steps: S1, cutting a sample into a rectangular sample; s2, clamping the rectangular sample into a clamp; s3, placing the clamped rectangular sample in a required environment, and applying pulling force to the two ends of the rectangular sample through a clamp; and S4, cutting the rectangular sample to complete the preparation of the section of the sample. Compared with the prior art, the method has the advantages that the shearing force during preparation of the section sample can be overcome under the condition that an ultrathin slicing machine is not used, the cost is reduced, and meanwhile, the microstructure analysis problem of the section sample is solved.

Description

Technical Field

[0001] The invention relates to the technical field of material analysis and testing, and in particular to a scanning electron microscope sample cross section and a preparation method and application thereof. Background Art

[0002] SEM (Scanning Electron Microscope) is a high-resolution microscope that uses an electron beam to scan the surface of a sample and obtains images through the signal generated by the interaction between the sample and the electron beam. It can be used to study the microstructure and composition of materials. In the field of new energy and polymer materials, SEM has a wide range of applications. For example, in the research of secondary lithium batteries, secondary lithium batteries have the advantages of high energy density, long cycle life and environmental friendliness, and are widely used in key fields such as portable electronic devices, electric vehicles, and energy storage power stations. Batteries include key components such as positive electrodes, negative electrodes, electrolytes, and separators. Both positive and negative electrode materials require current collectors for charge transfer. Common current collector materials are aluminum foil and copper foil, both of which have good conductivity and mechanical strength. The microstructure of the positive and negative electrode materials in the battery is very important. The material properties are closely related, which directly affects the battery performance and life. Therefore, it is necessary to characterize the microscopic morphology of battery materials through scanning electron microscopy to observe information such as thickness, structure, and particle distribution.

[0003] However, when using a scanning electron microscope to characterize the cross-section of battery materials, the electrode material generally requires atmosphere protection conditions for sample preparation, and liquid nitrogen quenching and other sample preparation methods are not applicable. In addition, the current collector material is easy to bend and deform, and the electrode material is relatively thin. Therefore, the deformation of the current collector caused by shear force can easily block the electrode material, thereby affecting the cross-sectional structure observation.

[0004] Patent CN 202311306955.5 discloses a method for preparing a thin film cross-section scanning electron microscope sample, which comprises applying epoxy resin conductive glue on a rectangular thin film sample, heating to a curing temperature to completely cure the epoxy resin conductive glue to obtain a cured thin film sample, removing the cured thin film sample and cutting it, and performing freeze-cross-section polishing to complete the preparation of the thin film sample. However, it is necessary to heat and cure the sample using epoxy resin conductive glue, and freeze-polish it, which is costly, and the preparation process involves heating, freezing, polishing and other processes, and the preparation environment is relatively limited. If the sample requires atmosphere protection, the above preparation process cannot be performed. Summary of the invention

[0005] The purpose of the present invention is to provide a scanning electron microscope sample cross section and a preparation method and application thereof to reduce costs.

[0006] The object of the present invention can be achieved by the following technical scheme: A method for preparing a scanning electron microscope sample cross section comprises the following steps:

[0007] S1: Cut the sample into a rectangular sample;

[0008] S2: Clamp the rectangular sample into the fixture;

[0009] S3: Place the clamped rectangular sample in the desired environment and apply tension to both ends of the rectangular sample through the clamp;

[0010] S4: Cut the rectangular sample under tension to complete the preparation of the sample cross section.

[0011] Preferably, the sample in step S1 includes a conductive substrate of a battery, a conductive substrate loaded with electrode materials, and a thin film.

[0012] Further preferably, the conductive substrate comprises aluminum foil or copper foil.

[0013] Further preferably, the electrode material includes lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, ternary material, sodium iron sulfate, and Prussian blue.

[0014] Further preferably, the film includes a separator in a lithium-ion battery, a catalyst-coated proton exchange membrane in a fuel cell, an alkaline anion exchange membrane, or a polymer film.

[0015] More preferably, the film comprises a perfluorosulfonic acid film.

[0016] Preferably, the rectangular sample in step S1 has a length of 10 to 30 mm and a width of 1 to 10 mm.

[0017] Preferably, the clamps in step S2 are clamped at both ends of the rectangular sample, and a gap of 2 to 20 mm is left between the clamps at both ends of the rectangular sample.

[0018] Preferably, the fixture in step S2 is a fixture provided by a tensile testing machine, a fixture provided by a dynamic mechanical thermal analyzer, or a fixture capable of measuring tensile force.

[0019] Further preferably, the fixture includes a base, a fixed table, a mobile table, a guide rail, a clamping member, a support table, a tensile gauge and a driving member. The fixed table is fixed on the base, the guide rail is fixed on the base, and the mobile table is slidably arranged on the guide rail. It can approach or move away from the fixed table under the guidance of the guide rail and the driving of the driving member. The fixed table and the mobile table are provided with clamping members for clamping rectangular samples on the opposite sides. A support table is provided between the fixed table and the mobile table to provide support when cutting the rectangular sample. A tensile gauge is also provided between the fixed table and the mobile table.

[0020] More preferably, the clamping member includes a first clamping plate, a second clamping plate and a locking member, the first clamping plate is fixed on a fixed table or a movable table, and the second clamping plate can be locked on the first clamping plate under the action of the locking member to achieve adjustment of the clamping force of the rectangular sample.

[0021] More preferably, the driving member comprises a pneumatic or hydraulic telescopic rod.

[0022] More preferably, the driving member includes a screw motor and a ball screw.

[0023] Preferably, the environment in step S3 includes room temperature environment, liquid nitrogen environment, and atmosphere protection environment.

[0024] Preferably, the pulling force in step S3 ranges from 0 to 10N.

[0025] Further preferably, the pulling force in step S3 ranges from 1 to 10N.

[0026] Further preferably, the tension range in step S3 is determined according to the stress-strain curve of the sample, and the tension range is within the elastic deformation region of the sample.

[0027] Preferably, the cutting in step S4 is performed using a blade.

[0028] Further preferably, the blade comprises a stainless steel blade or a glass blade.

[0029] Further preferably, the blade cuts perpendicularly to the rectangular sample.

[0030] A scanning electron microscope sample cross section is prepared by adopting the preparation method.

[0031] An application of the above-mentioned scanning electron microscope sample cross section is to use the scanning electron microscope sample cross section in the field of scanning electron microscope and X-ray spectrometer detection.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention can overcome the shear force during cross-section sample preparation without using an ultrathin slicer, thereby reducing costs and solving the problem of microstructure analysis of cross-section samples;

[0034] 2. The present invention can overcome the influence of shear force during the preparation of cross-sectional samples and improve the cross-sectional observation effect of samples susceptible to shear force;

[0035] 3. The fixture used in the present invention has a good fixing effect on the sample. The stretching sample preparation method used in the present invention solves the problem of the influence of shear force when preparing the cross section of samples such as aluminum foil / copper foil / film;

[0036] 4. The cross-section preparation method of the present invention has low cost, is applicable to a wide range of sample preparation environments, and can greatly improve the observation effect of the sample cross section;

[0037] 5. The present invention can stably apply a pulling force parallel to the sample surface to the sample through the design of the clamp, and support the sample through the support table to prevent the sample from being deformed under the cutting action of the blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the stress-strain curve of the aluminum foil sample of Example 1 of the present invention;

[0039] Figure 2 This is a scanning electron microscope image of a cross-section sample of an aluminum foil according to Example 1 of the present invention;

[0040] Figure 3 This is a scanning electron microscope image of the cross-section of the aluminum foil sample of Comparative Example 1;

[0041] Figure 4 The structure of the clamp of the present invention is shown in FIG. Figure 1 ;

[0042] Figure 5 The structure of the clamp of the present invention is shown in FIG. Figure 2 ;

[0043] In the figure: 1-base, 2-fixed platform, 3-movable platform, 4-guide rail, 5-clamping part, 6-support platform, 7-blade, 8-tensile meter, 9-driving part. DETAILED DESCRIPTION

[0044] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0045] Example 1

[0046] A method for preparing a scanning electron microscope sample cross section comprises the following steps:

[0047] S1: Cut the aluminum foil into a rectangular sample with a length of 10 mm and a width of 2 mm;

[0048] S2: Clamp the rectangular sample into the fixture of the dynamic thermomechanical analyzer, leaving a gap of 6.5 mm in the middle;

[0049] S3: Place the clamped rectangular sample at room temperature and use a dynamic thermomechanical analyzer to test the stress-strain curve of the rectangular sample. Figure 1 As shown, the straight line segment is the elastic deformation area, and the applied tension is selected to be 1N based on the stress and cross-sectional area calculation; the same conditions are used to apply a 1N tension to both ends of another rectangular sample of the same size;

[0050] S4: Use a stainless steel blade to cut on the rectangular sample to complete the preparation of the sample cross section.

[0051] Comparative Example 1

[0052] Compared with Example 1, most of the steps are the same, except that no tension is applied in step S3, and in step S4, scissors are used instead of stainless steel blades to prepare the sample cross section.

[0053] The cross-section samples obtained in Example 1 and Comparative Example 1 were observed under a scanning electron microscope, and the scanning electron microscope images thereof are as follows: Figure 2 and Figure 3 As shown, it can be found that the cross section of the aluminum foil of Example 1 can obtain a clear cross-sectional structure; while the cross section of the aluminum foil of Comparative Example 1 has many curved surfaces due to the influence of shear force.

[0054] Example 2

[0055] A method for preparing a scanning electron microscope sample cross section comprises the following steps:

[0056] S1: Cut the perfluorosulfonic acid membrane into a rectangular sample with a length of 30 mm and a width of 10 mm;

[0057] S2: Clamp the rectangular sample into the tensile machine, leaving a gap of 10 mm in the middle;

[0058] S3: Place the clamped rectangular sample at room temperature and apply a tensile force of 10N on both ends of the sample using a tensile testing machine;

[0059] S4: Use a stainless steel blade to cut on the rectangular sample to complete the preparation of the sample cross section.

[0060] Example 3

[0061] A method for preparing a scanning electron microscope sample cross section comprises the following steps:

[0062] S1: Cut the copper foil loaded with lithium iron phosphate into a rectangular sample with a length of 20 mm and a width of 5 mm;

[0063] S2: The rectangular sample was clamped into a homemade tensile fixture with a gap of 8 mm in the middle;

[0064] S3: Place the clamped rectangular sample in a glove box under atmosphere protection, and apply a tensile force of 1N on both ends of the sample using a homemade tensile fixture;

[0065] S4: Use a glass knife to cut on the rectangular sample to complete the preparation of the sample cross section.

[0066] In this embodiment, the structure of the self-made fixture is as follows: Figures 4-5 As shown, it includes a base 1, a fixed platform 2, a movable platform 3, a guide rail 4, a clamping member 5, a supporting platform 6, a dynamometer 8 and a driving member 9.

[0067] Among them, a fixed table 2 and a guide rail 4 are provided on the base 1, and a movable table 3 is slidably provided on the guide rail 4. The movable table 3 can approach or move away from the fixed table 2 along the guide rail 4 under the drive of the driving member 9. The fixed table 2 and the movable table 3 are both provided with a clamping member 5 on the facing side, which can clamp the rectangular sample. A support table 6 is provided between the fixed table 2 and the movable table 3, which can provide support when the blade 7 cuts the rectangular sample. A tensile meter 8 is also provided between the fixed table 2 and the movable table 3 to detect the tension at both ends of the rectangular sample.

[0068] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a scanning electron microscope sample cross section, characterized in that: The following steps are involved: S1: Cut the sample into a rectangular sample; S2: Clamp the rectangular sample into the fixture; S3: Place the clamped rectangular sample in the desired environment and apply tension to both ends of the rectangular sample through the clamp; S4: Cut the rectangular sample to complete the preparation of the sample cross section.

2. The method for preparing a scanning electron microscope sample cross section according to claim 1, characterized in that: The sample in step S1 includes a conductive substrate of a battery, a conductive substrate loaded with electrode materials, and a thin film.

3. The method for preparing a scanning electron microscope sample cross section according to claim 1, characterized in that: The rectangular sample in step S1 has a length of 10 to 30 mm and a width of 1 to 10 mm.

4. The method for preparing a scanning electron microscope sample cross section according to claim 1, characterized in that: In step S2, the clamps are clamped at both ends of the rectangular sample, and a gap of 2 to 20 mm is left between the clamps at both ends of the rectangular sample.

5. The method for preparing a scanning electron microscope sample cross section according to claim 1, characterized in that: The environment in step S3 includes room temperature environment, liquid nitrogen environment, and atmosphere protection environment.

6. The method for preparing a scanning electron microscope sample cross section according to claim 1, characterized in that: The pulling force in step S3 ranges from 0 to 10N.

7. The method for preparing a scanning electron microscope sample cross section according to claim 6, characterized in that: The tension range in step S3 is determined according to the stress-strain curve of the sample, and the tension range is within the elastic deformation range of the sample.

8. The method for preparing a scanning electron microscope sample cross section according to claim 1, characterized in that: The cutting in step S4 is performed using a blade, which includes a stainless steel blade and a glass blade.

9. A scanning electron microscope sample cross section, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. An application of the scanning electron microscope sample cross section according to claim 9, characterized in that: The scanning electron microscope sample cross section is used in the field of scanning electron microscope and X-ray energy spectrometer detection.

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