阅读说明：本技术 一种锂电材料截面扫描电镜样品的制备方法和应用 (Preparation method and application of cross-section scanning electron microscope sample of lithium battery material ) 是由 谢堂锋 陈若葵 巩勤学 蒋快良 蔡罗蓉 王明 李长东 于 2020-12-15 设计创作，主要内容包括：本发明属于材料分析测试技术领域,提供一种锂电材料截面扫描电镜样品的制备方法和应用,本方法包括以下步骤：取锂电材料置于金属箔上,加入银导电胶搅拌混合,得到浆稠状锂电材料样品,折叠金属箔并包裹住银导电胶浆稠状锂电材料样品,得到锂电材料样品包埋件,对银导电胶锂电材料样品包埋件进行压合,干燥,得到固化锂电材料样品包埋件,对银导电胶固化锂电材料样品包埋件进行裁切,再用氩离子束进行截面抛光,即得锂电材料截面扫描电镜样品。本发明操作简单,使用金属箔及银导电胶对锂电材料样品进行包埋,避免了粉体样品直接涂覆在硅片上可能导致的涂覆层破碎与脱落对仪器造成的污染。(The invention belongs to the technical field of material analysis and test, and provides a preparation method and application of a lithium battery material cross-section scanning electron microscope sample, wherein the method comprises the following steps: the method comprises the steps of taking a lithium battery material, placing the lithium battery material on a metal foil, adding silver conductive adhesive, stirring and mixing to obtain a thick lithium battery material sample, folding the metal foil, wrapping the silver conductive adhesive thick lithium battery material sample, obtaining a lithium battery material sample embedded part, pressing the silver conductive adhesive lithium battery material sample embedded part, drying, obtaining a solidified lithium battery material sample embedded part, cutting the silver conductive adhesive solidified lithium battery material sample embedded part, and performing section polishing by using argon ion beams to obtain a lithium battery material section scanning electron microscope sample. The method is simple to operate, and the lithium battery material sample is embedded by using the metal foil and the silver conductive adhesive, so that the pollution to an instrument caused by the breakage and falling of a coating layer possibly caused by the fact that the powder sample is directly coated on a silicon chip is avoided.)

1. The preparation method of the cross-section scanning electron microscope sample of the lithium battery material is characterized by comprising the following steps of:

(1) placing the lithium battery material on a metal foil, adding a silver conductive adhesive, stirring and mixing to obtain a thick lithium battery material sample;

(2) folding a metal foil to wrap the thick lithium battery material sample to obtain a lithium battery material sample embedded part;

(3) pressing and drying the lithium battery material sample embedded part to obtain a solidified lithium battery material sample embedded part;

(4) and cutting the solidified lithium battery material sample embedded part, and then polishing the section by using an argon ion beam to obtain the lithium battery material section scanning electron microscope sample.

2. The production method according to claim 1, wherein step (1) further comprises subjecting the metal foil to the following steps: cutting the metal foil into a square with the side length of 30-45mm, cleaning and flattening the square, and folding the two ends of the metal foil towards the middle to enable the metal foil to be evenly divided into three parts by the two folding lines.

3. The method according to claim 1, wherein in the step (1), the conductive silver paste is one of a conductive silver paste of acetone or a conductive silver paste of isobutyl methyl ketone.

4. The preparation method according to claim 1, wherein in the step (1), the mass ratio of the silver conductive adhesive to the lithium battery material is 1 (3-6).

5. The method of claim 1, wherein the metal foil is one of a tin foil, an aluminum foil, or a copper foil.

6. The production method according to claim 1, wherein in the step (2), the folding is performed by folding both ends of the metal foil toward the middle so that both ends are overlapped, and fixing the overlapped portion by adhesion.

7. The preparation method according to claim 1, wherein in the step (3), the drying temperature is 40-70 ℃ and the drying time is 30-120 min.

8. The preparation method according to claim 1, wherein in the step (4), the cutting is performed in a manner that a blade is cut at a time perpendicular to the middle position of the solidified lithium battery material sample embedded part.

9. The method according to claim 1, wherein in the step (4), the parameters for the section polishing by the argon ion beam are as follows: the voltage of the ion beam is 5-7 kV, the current of the ion beam is 1.5-3.5 mA, and the polishing time is 100-300 min.

10. Use of a cross-sectional scanning electron microscope sample of a lithium battery material according to any one of claims 1 to 9 in the observation and analysis of a scanning electron microscope.

Technical Field

The invention relates to the technical field of material analysis and testing, in particular to a preparation method and application of a lithium battery material cross-section scanning electron microscope sample.

Background

In recent years, with the rapid development of new energy automobile industry, lithium ion batteries have the advantages of high capacity, long cycle life, small self-discharge rate, high charge and discharge speed, environmental protection and the like, and are regarded as a new generation of green high-energy batteries with the development prospect in the new century, and the demand of the batteries is increased explosively. However, the current lithium ion battery has some imperfect disadvantages, such as high production cost, insufficient stability, poor safety performance, etc. The positive electrode material of the lithium ion battery is a core component of the lithium ion battery, the microstructure of the positive electrode material is an important factor influencing the performance of the lithium ion battery, and an accurate representation and test method of the microstructure of the positive electrode material of the lithium ion battery is of great importance for developing a novel positive electrode material with more excellent comprehensive performance.

Scanning Electron Microscopy (SEM) is an important analytical tool for characterizing the microstructure of lithium ion battery materials. Because the chemical property of the lithium ion battery anode material is more active, the surface and the internal structure of the lithium ion battery anode material have certain difference, in order to comprehensively observe the real internal structure composition, cracks, pores and other microscopic defects of the lithium ion battery anode material, a proper section sample preparation method is required to obtain a lithium ion battery anode material section sample with good reproducibility and high flatness for the observation and analysis of a scanning electron microscope.

The prior art discloses a method for preparing a section sample for representing the radial element distribution of an NCM anode material, wherein liquid resin is used as a filler to solidify the material, sand paper is used for grinding to prepare a powder section sample, but the resin is non-conductive, and image drift or charge phenomenon is easy to generate during subsequent scanning electron microscope observation, so that the analysis is difficult, and the sand paper grinding easily causes mechanical damage to the sample, the surface smoothness is poor, and the real accuracy of an analysis result is influenced; the method is characterized in that liquid carbon conductive glue and pearlescent pigment are mixed and directly coated on the surface of a silicon wafer, but the initial sample after direct drying is broken or dropped to pollute an instrument when the ion beam cross section is polished, so that the service life of the instrument is shortened.

Disclosure of Invention

The invention aims to provide a preparation method and application of a lithium battery material cross-section scanning electron microscope sample.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a lithium battery material cross section scanning electron microscope sample comprises the following steps:

(1) placing the lithium battery material on a metal foil, adding a silver conductive adhesive, stirring and mixing to obtain a thick lithium battery material sample;

(2) folding a metal foil to wrap the thick lithium battery material sample to obtain a lithium battery material sample embedded part;

(3) pressing and drying the lithium battery material sample embedded part to obtain a solidified lithium battery material sample embedded part;

(4) and cutting the solidified lithium battery material sample embedded part, and then polishing the section by using an argon ion beam to obtain the lithium battery material section scanning electron microscope sample.

Preferably, the lithium battery material is a lithium ion battery positive electrode material or a lithium ion battery positive electrode material precursor, specifically a ternary nickel cobalt manganese precursor, ternary nickel cobalt lithium manganate, ternary nickel cobalt aluminum hydroxide, ternary nickel cobalt lithium aluminate, iron phosphate, lithium cobaltate or lithium manganate.

Preferably, step (1) further comprises processing the metal foil by the following steps: cutting the metal foil into a square with the side length of 30-45mm, cleaning and flattening the square, and folding the two ends of the metal foil towards the middle to enable the metal foil to be evenly divided into three parts by the two folding lines.

Preferably, the cleaning is performed by wiping with alcohol or acetone.

Preferably, the amount of the lithium battery material is 0.1-0.2 g.

Preferably, in the step (1), the silver conductive adhesive is acetone silver conductive adhesive or isobutyl methyl ketone silver conductive adhesive.

Preferably, in the step (1), the mass ratio of the silver conductive adhesive to the lithium battery material is 1 (3-6), and the forming and viscosity of the slurry lithium battery material sample are preferably 1: 5.

Preferably, the metal foil is one of tin foil paper, aluminum foil paper or copper foil paper.

Preferably, in the step (1), the stirring time is 30-120 s, and more preferably 60 s.

Preferably, in the step (2), the two ends of the metal foil are folded towards the middle so that the two ends are overlapped, and the overlapped part is fixed by gluing, so that the metal foil is smoothly attached to the lithium battery material without wrinkles and bubbles. Preferably, a water-resistant gel-type gel is used for fixation.

Preferably, in the step (3), the lithium battery material sample embedded part is placed in a manner that the surface of the single-layer metal foil faces upwards and the surface of the double-layer metal foil faces downwards before lamination, and the double layer is formed by overlapping two ends of the metal foil when the metal foil is folded.

Preferably, in the step (3), the pressing is performed in a one-time pressing manner, and a glass slide is covered on the lithium battery material sample embedding piece before the pressing.

Preferably, in the step (3), the drying temperature is 40-70 ℃, and the drying time is 30-120 min.

Preferably, in the step (4), the cutting is performed in a manner that the blade performs one-time cutting perpendicular to the middle position of the solidified lithium battery material sample embedded part.

Preferably, in the step (4), the parameters of the section polishing by the argon ion beam are as follows: the voltage of the ion beam is 5-7 kV, the current of the ion beam is 1.5-3.5 mA, and the polishing time is 100-300 min.

Preferably, in the step (4), the surface of the cut solidified lithium battery material sample embedded part facing the ion beam direction is a single-layer metal foil surface.

The invention also provides application of the lithium battery material cross section scanning electron microscope sample in scanning electron microscope observation and analysis.

The invention has the advantages that:

1. according to the method, the argon ion polishing is used for preparing the lithium battery material section sample, the operation is simple, the high-temperature-resistant and good-ductility metal foil and the high-temperature-resistant and good-conductivity silver conductive adhesive with low resistance and high bonding strength are innovatively used for embedding the lithium battery material sample, and the pollution to an instrument caused by the fact that a coating layer is broken and falls off when the powder sample is directly coated on a silicon wafer is avoided.

2. Compared with liquid carbon conductive adhesive, the silver conductive adhesive used in the invention has stronger conductivity and lower resistance, can reduce the degree of image drift and charge generation during the observation of a scanning electron microscope, and effectively improves the imaging quality during the imaging of the scanning electron microscope.

3. Compared with a mechanical polishing method, the preparation of the pretreatment sample is quicker, the section flatness is better, the shearing stress and the tensile deformation in the sample preparation process are reduced, the mechanical damage of the lithium battery material sample is avoided, a wider section observation area can be obtained, the integrity and the stability are better, the defects of the internal structure, the crystal orientation, the cracks, the porosity and the like of the lithium battery material nano particles can be fully analyzed, and the accuracy of sample detection is greatly improved.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic process flow diagram of the present invention;

FIG. 2 is a scanning electron micrograph of a cross-sectional sample of iron phosphate prepared in example 1 of the present invention;

FIG. 3 is a scanning electron microscope image of a sample of a cross-section of a ternary Ni-Co-Mn precursor prepared in example 2 of the present invention;

FIG. 4 is an enlarged view of a portion of FIG. 3;

FIG. 5 is a scanning electron micrograph of a cross-sectional sample of lithium cobaltate prepared in example 3 of the present invention.

Detailed Description

For a further understanding of the invention, preferred embodiments of the invention are described below with reference to the examples to further illustrate the features and advantages of the invention, and any changes or modifications that do not depart from the gist of the invention will be understood by those skilled in the art to which the invention pertains, the scope of which is defined by the scope of the appended claims.

Example 1

A preparation method of a ferric phosphate cross-section scanning electron microscope sample comprises the following steps:

(1) cutting the aluminum-foil paper into a square shape of 30mm multiplied by 30mm, cleaning and flattening the square shape by dipping a cotton swab in acetone, and slightly folding two ends of the aluminum-foil paper inwards to enable the aluminum-foil paper to be evenly divided into three parts by two folding lines;

(2) unfolding the folded aluminum foil paper, placing 0.1g of iron phosphate sample in the middle third of the matte surface of the aluminum foil paper, adding acetone silver conductive adhesive (product code: 16062) of American TED PELLA company as a binder into the iron phosphate to obtain a mixed sample, and controlling the mass ratio of the acetone silver conductive adhesive to the iron phosphate to be 1: 4;

(3) rapidly stirring the mixed sample for 60s, and fully infiltrating to obtain a thick ferric phosphate sample;

(4) folding one third of two sides of the aluminum foil paper towards the middle direction of the thick ferric phosphate sample to enable the aluminum foil paper at two ends to be overlapped, keeping one side edge aligned, fixing the overlapped aluminum foil paper at two ends together by using Baide jelly glue, wherein the gluing position is 2, enabling the aluminum foil paper to be flatly attached to the thick ferric phosphate sample to obtain the required ferric phosphate sample embedded part;

(5) putting the iron phosphate sample embedding piece on a flat desktop with the single-layer aluminum foil paper surface facing upwards and the double-layer aluminum foil paper surface facing downwards, covering a glass slide and pressing once to uniformly open the thick iron phosphate sample in the iron phosphate sample embedding piece until the thickness is uniform;

(6) further placing the pressed iron phosphate sample embedded part in a 50 ℃ forced air drying oven for drying for 120min to obtain a solidified iron phosphate sample embedded part;

(7) placing the solidified ferric phosphate sample embedded part on a flat desktop, and vertically cutting the middle position of a single-layer aluminum foil paper surface of the solidified ferric phosphate sample embedded part by using a blade at one time to obtain a ferric phosphate sample embedded part to be polished;

(8) adhering the iron phosphate sample embedding piece to be polished on a special sample table for cross section polishing, then loading the special sample table for cross section polishing loaded with the iron phosphate sample embedding piece into an argon ion beam polisher, enabling the ion beam emission direction to be perpendicular to the single-layer aluminum foil paper surface of the iron phosphate sample embedding piece to be polished, performing ion beam cross section polishing, controlling the voltage of an ion beam to be 6kV, the current of the ion beam to be 3mA, and the polishing time to be 150min, thus obtaining the iron phosphate cross section scanning electron microscope sample for scanning electron microscope observation.

Fig. 2 is a scanning electron microscope imaging image of a cross-sectional sample of iron phosphate prepared in example 1, and it can be seen from fig. 2 that iron phosphate particles of different shapes and sizes are completely embedded in a silver conductive adhesive, and the iron phosphate particles are not broken, and the cross section is smooth and flat, and has no obvious scratch, so that the cross-sectional morphology of the powder particles and the distribution of the internal pore structure defects of the particles can be clearly observed.

Example 2

A preparation method of a ternary nickel-cobalt-manganese precursor sample section sample comprises the following steps:

(1) cutting the tin foil paper into a square shape of 40mm multiplied by 40mm, cleaning and flattening the tin foil paper by dipping cotton swabs in alcohol, and slightly folding two ends of the tin foil paper inwards to enable the tin foil to be evenly divided into three parts by two folding lines;

(2) unfolding the folded tin foil, placing 0.15g of a ternary nickel-cobalt-manganese precursor sample in the middle third of the matte surface of the tin foil, adding isobutyl methyl ketone silver conductive adhesive (product code: 16040-30) of TED PELLA company in America as a binder into the ternary nickel-cobalt-manganese precursor to obtain a mixed sample, and controlling the mass ratio of the isobutyl methyl ketone silver conductive adhesive to the ternary nickel-cobalt-manganese precursor to be 1: 5;

(3) rapidly stirring the mixed sample for 90s, and fully infiltrating to obtain a thick paste ternary nickel cobalt manganese precursor sample;

(4) folding one third of two sides of the tinfoil paper towards the middle of the thick ternary nickel-cobalt-manganese precursor sample to enable the tinfoil paper at two ends to be overlapped, keeping one side edge aligned, fixing the tinfoil paper at two overlapped ends together by using Baide jelly glue, enabling the tinfoil paper and the thick ternary nickel-cobalt-manganese precursor sample to be flatly attached at the gluing position of 3 positions, and obtaining the required ternary nickel-cobalt-manganese precursor sample embedded part;

(5) putting the single-layer tinfoil paper surface of the ternary nickel-cobalt-manganese precursor sample embedded part on a flat table surface, covering a glass slide, and pressing once to uniformly open the thick ternary nickel-cobalt-manganese precursor sample in the ternary nickel-cobalt-manganese precursor sample embedded part until the thickness is uniform;

(6) further placing the pressed ternary nickel-cobalt-manganese precursor sample embedded part in a 60 ℃ forced air drying oven for drying for 90min to obtain a solidified ternary nickel-cobalt-manganese precursor sample embedded part;

(7) placing the solidified ternary nickel-cobalt-manganese precursor sample embedded part on a flat desktop, and vertically cutting the middle position of the single-layer tinfoil paper surface of the solidified ternary nickel-cobalt-manganese precursor sample embedded part by using a blade at one time to obtain a ternary nickel-cobalt-manganese precursor sample embedded part to be polished;

(8) adhering a ternary nickel-cobalt-manganese precursor sample embedding piece to be polished on a special sample table for cross section polishing, then loading the special sample table for cross section polishing loaded with the ternary nickel-cobalt-manganese precursor sample embedding piece into an argon ion beam polisher, enabling the emission direction of an ion beam to be perpendicular to the single-layer tin foil paper surface of the ternary nickel-cobalt-manganese precursor sample embedding piece to be polished, performing ion beam cross section polishing, controlling the ion beam voltage to be 7kV, the ion beam current to be 2.5mA, and the polishing time to be 120min, and obtaining the ternary nickel-cobalt-manganese precursor sample cross section sample for scanning electron microscope observation.

Fig. 3 and 4 are a scanning electron microscope image and a partial enlarged view of a cross-sectional sample of the ternary nickel-cobalt-manganese precursor prepared in example 2. As can be seen from FIG. 3, the ternary nickel-cobalt-manganese precursor particles embedded in the middle of the cross sections of the single-layer tin foil paper and the double-layer tin foil paper are composed of a plurality of nano spheroidal particles which are uniformly distributed in particle size and closely stacked together, and the cross section observation area is large, the cross section is smooth and flat, and no obvious scratch is caused. As can be seen from FIG. 4, the spheroidal particles with different sizes are completely embedded in the silver conductive adhesive, and are not broken, the section flatness is high, and the distribution of the defects of the section morphology of the powder particles and the pore structure inside the particles can be clearly observed.

Example 3

A preparation method of a lithium cobaltate sample cross section sample comprises the following steps:

(1) cutting the copper foil paper into a square shape of 50mm multiplied by 50mm, cleaning and flattening the copper foil paper by dipping cotton swabs in alcohol, and slightly folding the two ends of the copper foil paper inwards to enable the copper foil to be evenly divided into three parts by two folding lines;

(2) unfolding the folded copper foil paper, placing 0.2g of a lithium cobaltate sample in the middle third of the matte surface of the copper foil paper, adding isobutyl methyl ketone silver conductive adhesive (product code: 16040-30) of the American TED PELLA company as a binder into the lithium cobaltate sample to obtain a mixed sample, and controlling the mass ratio of the isobutyl methyl ketone silver conductive adhesive to the lithium cobaltate sample to be 1: 4;

(3) rapidly stirring the mixed sample for 90s, and fully soaking to obtain a thick slurry lithium cobaltate sample;

(4) folding one third of two sides of the copper foil paper towards the middle direction of the thick lithium cobaltate sample to enable the copper foil paper at two ends to be overlapped, keeping one side edge to be aligned, fixing the overlapped copper foil paper at two ends together by using Baide jelly glue, and enabling the copper foil paper and the thick lithium cobaltate sample to be flatly attached at the gluing position of 3 positions to obtain a required lithium cobaltate sample embedded part;

(5) the method comprises the following steps of enabling a single-layer copper foil paper surface of a lithium cobaltate sample embedding piece to face upwards, enabling a double-layer copper foil paper surface to face downwards, placing the lithium cobaltate sample embedding piece on a flat desktop, covering a glass slide, and pressing once to enable thick lithium cobaltate samples in the lithium cobaltate sample embedding piece to be evenly opened until the thickness is uniform;

(6) further placing the pressed lithium cobaltate sample embedded part in a 70 ℃ forced air drying oven for drying for 60min to obtain a solidified lithium cobaltate sample embedded part;

(7) placing the solidified lithium cobaltate sample embedded part on a flat desktop, and vertically cutting the middle position of the single-layer copper foil paper surface of the solidified lithium cobaltate sample embedded part by using a blade at one time to obtain a lithium cobaltate sample embedded part to be polished;

(8) adhering a lithium cobaltate sample embedding piece to be polished on a special sample table for cross section polishing, then loading the special sample table for cross section polishing loaded with the lithium cobaltate sample embedding piece into an argon ion beam polisher, enabling the ion beam emission direction to be perpendicular to the single-layer copper foil surface of the lithium cobaltate sample embedding piece to be polished, performing ion beam cross section polishing, controlling the ion beam voltage to be 7kV, the ion beam current to be 2.5mA, and the polishing time to be 180min, thus obtaining the lithium cobaltate sample cross section sample for scanning electron microscope observation.

Fig. 5 is a scanning electron microscope imaging image of a cross-section sample of lithium cobaltate prepared in example 3, and it can be seen from fig. 5 that lithium cobaltate particles with different shapes and sizes are completely embedded in the silver conductive adhesive, without breaking, and the cross-section is smooth and flat, without obvious scratches, and the cross-section morphology of the powder particles and the distribution of the pore structure defects inside the particles can be clearly observed.

The above detailed description of the method and application of the cross-sectional scanning electron microscope sample of the lithium battery material provided by the present invention is provided, and the principle and the embodiment of the present invention are described herein by using the specific embodiment, which is only used to help understand the method of the present invention and the core idea thereof, including the best mode, and also to enable any person skilled in the art to practice the present invention, including making and using any device or system, and implementing any method in combination. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.