Battery section sample preparation method

Abstract

A battery section sample preparation method comprises the following steps: S1, battery embedding sample preparation: winding a battery cell by using an adhesive tape or a thin film, then putting the battery cell into a mold, and pouring a wrapper into the mold for wrapping the battery cell to obtain an embedded block; s2, linear cutting: carrying out linear cutting on the insert block to obtain a battery section insert block; s3, grinding and polishing: grinding and polishing the battery section insert block to obtain the battery section insert block with a flat section; s4, argon ion polishing: the battery section mosaic block is placed on a sample table, an argon ion polishing device is used for polishing, the included angle between the emission direction of an argon ion beam of the argon ion polishing device and the plane where the section of the battery section mosaic block is located is 0-45 degrees, and the battery section mosaic block can rotate in the horizontal direction in the polishing process; and S5, taking out a battery section sample, thereby preparing an actual battery overall section with submicron flatness, a centimeter-level observation area and undamaged components, and laying a solid foundation for subsequent multi-mode ex-situ and in-situ working condition observation.

Description

Technical Field

[0001] The invention relates to the technical field of material testing, and in particular to a battery cross-section sample preparation method. Background Art

[0002] Batteries are widely used in a variety of electronic devices, bringing great convenience to people's lives. How to prepare qualified battery cross-sections to study related characterizations has always been the goal pursued by technicians in this field. However, there are currently few reports on the sample preparation and research of the overall cross-section of batteries. This is because, on the one hand, there are currently few studies on some mesoscopic-scale battery reaction behaviors occurring at the battery scale, such as the reaction uniformity and failure uniformity of electrodes and diaphragms at different spatial positions in actual commercial batteries under different charging and discharging conditions. On the other hand, there are also few studies on in-situ reactions of the overall cross-section of batteries. It is worth noting that it is necessary to take actual batteries as the research object to explore the relevant battery and electrode reaction behavior research under non-in-situ and in-situ conditions. Therefore, it is necessary to develop a battery cross-section sample preparation technology that takes the macroscopic battery as a whole as the object to provide technical support for studying the electrochemical reaction mechanism occurring at the battery and electrode levels. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a novel method for preparing battery cross-section samples.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for preparing a battery cross-section sample comprises the following steps:

[0006] S1 Battery embedding sample preparation: Use tape or film to wrap the battery cell, and put the wrapped and sealed battery cell into the mold, pour the wrapping material into the mold to wrap the battery cell, and obtain the mosaic block after the wrapping material solidifies;

[0007] S2 wire cutting: using wire cutting equipment to wire cut the mosaic block to obtain a battery cross-section mosaic block;

[0008] S3 grinding and polishing: grinding and polishing the side of the battery cross-section mosaic block where the battery cross-section is exposed, using sandpaper of different meshes from low mesh to high mesh to grind and polish, so as to obtain a battery cross-section mosaic block with a flat cross-section;

[0009] S4 argon ion polishing: the battery cross-section mosaic block is fixedly placed on the sample table, and the battery cross-section mosaic block is polished using an argon ion polishing device, wherein the emission direction of the argon ion beam of the argon ion polishing device and the plane where the cross-section of the battery cross-section mosaic block is located are at an angle of 0 to 45°, and during the argon ion polishing process, the battery cross-section mosaic block can rotate around the horizontal direction;

[0010] S5 Removal of battery cross-section samples: Use wire cutting equipment to cut the packaging outside the battery cross-section mosaic block and remove the battery cross-section sample.

[0011] In some embodiments, the argon ion polishing equipment has two argon ion guns. In step S4, the argon ion guns are symmetrically arranged on both sides of the battery cross-section mosaic block.

[0012] In some embodiments, in step S4, the battery cross-section mosaic block can be rotated 360° around the horizontal direction.

[0013] In some embodiments, the emission direction of the argon ion beam of the argon ion polishing equipment is at an angle of 0° to the plane where the cross-section of the battery cross-section mosaic block is located, the argon ion beam is emitted by an argon ion gun, and the cross-section of the battery cross-section mosaic block remains horizontal and aligned with the center hole of the argon ion gun.

[0014] In some embodiments, the battery type is one of a soft-pack battery, a cylindrical battery, a square battery, and a monolithic battery.

[0015] In some embodiments, the battery cell is a dry cell without liquid injection, or a cell that has been charged and discharged.

[0016] In some embodiments, when the battery cell is wound, the battery cell is wound and sealed as a whole, and no part of the battery cell is exposed.

[0017] In some embodiments, the wrapping material is a mixture of resin and curing agent, wherein the mass ratio of the resin to the curing agent is 10:2-3.

[0018] In some embodiments, in step S4, low temperature argon ion polishing is performed, and the freezing temperature is ≤-20°C.

[0019] In some embodiments, in step S5, before using diamond wire to cut the outer covering of the battery cross-section mosaic block, it is necessary to cover and protect the battery cross-section with a blue film.

[0020] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0021] The present invention discloses a method for preparing a sample of a battery cross section by using multiple technologies. The method comprehensively uses inlay technology, wire cutting technology, grinding and polishing technology, argon ion polishing technology, etc. The method can directly or indirectly prepare samples of dry cells that have not been charged and discharged and cells that have been charged and discharged, and obtain an overall cross section of the battery with nanometer-level flatness, so as to further perform in-situ and ex-situ characterization for research on the charge and discharge mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of wire cutting equipment;

[0023] Figure 2 It is a schematic diagram of the argon ion polishing equipment;

[0024] Figure 3 This is a scanning electron microscope image of the battery cross section after polishing with an argon ion polishing device;

[0025] In the figure:

[0026] 1—battery cell; 2—diamond wire cutting equipment; 3—argon ion gun; 4—argon ion polishing equipment sample stage; 5—battery cross-section mosaic block; 6—argon ion beam; 7—argon ion polishing equipment sample stage base. DETAILED DESCRIPTION

[0027] The present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0028] like Figure 1 and Figure 2 As shown, the present invention provides a battery cross-section sample preparation method, taking a commercial Bluetooth headset battery cell with a capacity of 350mAh without liquid injection as an example, comprising the following steps:

[0029] S1 Battery embedding sample preparation: Take out the battery cell 1 of the Bluetooth headset and embed it. Use raw tape to wrap the sides, top and bottom of the battery cell 1 tightly and completely seal it, fix it with a clip and a 50um stainless steel sheet and place it vertically in a soft rubber mold with an inner diameter of 30mm, pour in a resin and curing agent mixed with a mass ratio of 10:3 and evenly mix the glue for embedding, and place it in a 30℃ oven for 24 hours to obtain an embedded block.

[0030] S2 wire cutting: see Figure 1 The mosaic block is cut by a diamond wire cutting device 2 to obtain a battery cross-section mosaic block 5. During the wire cutting process, the cutting speed is 2 mm / min, the cutting position is in the middle of the battery cell, and the cutting speed is 250 revolutions.

[0031] S3 grinding and polishing: Perform manual grinding and polishing on the side of the battery cross-section mosaic block 5 that exposes the battery cross-section, and use 240 mesh, 600 mesh, 1000 mesh, 1500 mesh, and 2000 mesh sandpapers to slowly grind and polish in sequence, and then use 3000 mesh and 5000 mesh sponge sandpapers in sequence for automatic grinding and polishing at a rotation speed of 600 rpm to obtain a battery cross-section mosaic block 5 with a flat cross-section.

[0032] S4 Cryo-argon ion polishing. An argon ion polishing device equipped with two argon ion guns 3 is selected, and the battery cross-section mosaic block is fixed on the sample stage 4 of the argon ion polishing device. The argon ion guns 3 are symmetrically arranged on both sides of the battery cross-section mosaic block 5. The cross section of the battery cross-section mosaic block 5 is kept horizontal and aligned with the center hole of the argon ion gun 3. The emission direction of the argon ion beam 6 is at an angle of 0° with the plane where the cross section of the battery cross-section mosaic block 5 is located. The ambient freezing temperature is -30°C. The sample stage 4 of the argon ion polishing device drives the battery cross-section mosaic block 5 to rotate horizontally, and the rotation angle ranges from 0 to 360° to obtain a battery cross section with nano-level flatness.

[0033] S5 Battery cross-section sample extraction: After argon ion polishing, the battery cross-section mosaic block 5 is covered with a blue film with dust-free paper on the exposed part of the battery cross-section. The two sides are cut with a diamond wire cutting device 2, and then two pliers are used to break it apart, and the battery cross-section sample is taken out and saved. It is placed in a specific in-situ charging and discharging device for in-situ electrochemical reaction behavior observation.

[0034] S6 Battery cross-section sample morphology characterization: Fix the battery cross-section sample on the sample stage and put it into the field emission scanning electron microscope to observe the battery tissue morphology. The scanning electron microscope shooting parameters are low voltage 1kV and low vacuum mode. Figure 3 As shown, it can be clearly seen that the inside of the Bluetooth headset battery is wound, the cross-section is smooth and flat, the cross-sectional morphology of the battery cell can be clearly and intuitively seen, and the positive electrode, negative electrode and diaphragm areas can be distinguished, and the widths of the above three areas can be specifically measured.

[0035] In step S1, the battery cell 1 is a dry cell without liquid injection, or a cell that has been charged and discharged. The cell after charging and discharging needs to be centrifuged 3 to 5 times using a high-speed centrifuge to obtain a cell with trace amounts of electrolyte salt. For cells that have been charged and discharged, all steps of centrifugation, embedding, wire cutting, grinding and polishing, and argon ion polishing need to be completed in a dry room or an inert glove box. For dry cells that have not been injected with liquid, the indoor humidity needs to be maintained at ≤30%. In some embodiments, the battery capacity of the present invention is ≤10000mAh. In some embodiments, the mosaic block is obtained by curing in an oven at 20 to 45°C for ≤24h.

[0036] In step S4, in some embodiments, the angle between the emission direction of the argon ion beam 6 and the plane where the cross section of the battery cross section mosaic block 5 is located is 0-45°. In some embodiments, the angle between the emission direction of the argon ion beam 6 and the plane where the cross section of the battery cross section mosaic block 5 is located is 0-35°, that is, the argon ion beam 6 can extend obliquely from bottom to top, or can extend obliquely from top to bottom, or can extend horizontally. In some embodiments, the acceleration voltage of the argon ion gun 3 is ≤10.0kV, the polishing time is ≤24h, and the ambient freezing temperature is controlled to be ≤-20°C. The preferred polishing conditions are: the acceleration voltage and time of the argon ion gun 3 are 8.0kV-60min, 7.0kV-90min, and 5.0kV-120min, respectively, the ambient freezing temperature is controlled to be -30°C, the angle between the argon ion gun 3 and the horizontal plane is 0°, and the battery cross section mosaic block 5 is rotated horizontally at an angle of 360°. By setting the emission direction of the argon ion beam 6 to be as parallel as possible to the plane where the cross section of the battery cross section mosaic block 5 is located, the flatness of the cross section of the battery cross section mosaic block 5 after polishing can be improved. By arranging the battery cross-section mosaic block to be rotatable 360° horizontally, the polishing of the cross-section is made more uniform.

[0037] In some embodiments, the battery type is one of a soft pack battery, a cylindrical battery, a square battery, and a monolithic battery. In some embodiments, the battery is specifically a lithium battery. The thickness of the positive electrode ranges from 1 to 500 um, the thickness of the negative electrode ranges from 1 to 500 um, and the thickness of the separator ranges from 1 to 200 um.

[0038] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery cross-section sample preparation method, characterized in that: Includes steps: S1 Battery embedding sample preparation: Use tape or film to wrap the battery cell, and put the wrapped and sealed battery cell into the mold, pour the wrapping material into the mold to wrap the battery cell, and obtain the mosaic block after the wrapping material solidifies; S2 wire cutting: using wire cutting equipment to wire cut the mosaic block to obtain a battery cross-section mosaic block; S3 grinding and polishing: grinding and polishing the side of the battery cross-section mosaic block where the battery cross-section is exposed, using sandpaper of different meshes from low mesh to high mesh to grind and polish, so as to obtain a battery cross-section mosaic block with a flat cross-section; S4 argon ion polishing: the battery cross-section mosaic block is fixedly placed on the sample table, and the battery cross-section mosaic block is polished using an argon ion polishing device, wherein the emission direction of the argon ion beam of the argon ion polishing device and the plane where the cross-section of the battery cross-section mosaic block is located are at an angle of 0 to 45°, and during the argon ion polishing process, the battery cross-section mosaic block can be rotated in a horizontal direction; S5: Removing the battery cross-section sample: using the wire cutting device to cut the wrapping outside the battery cross-section mosaic block, and taking out the battery cross-section sample.

2. The battery cross-section sample preparation method according to claim 1, characterized in that: The argon ion polishing equipment has two argon ion guns. In step S4, the argon ion guns are symmetrically arranged on both sides of the battery cross-section mosaic block.

3. The battery cross-section sample preparation method according to claim 1, characterized in that: In step S4, the battery cross-section mosaic block can be rotated 360° around the horizontal direction.

4. The battery cross-section sample preparation method according to claim 1, characterized in that: The emission direction of the argon ion beam of the argon ion polishing equipment is at an angle of 0° to the plane where the cross section of the battery cross section mosaic block is located. The argon ion beam is emitted by an argon ion gun, and the cross section of the battery cross section mosaic block remains horizontal and aligned with the center hole of the argon ion gun.

5. The battery cross-section sample preparation method according to claim 1, characterized in that: The battery type is one of a soft-pack battery, a cylindrical battery, a square battery, and a single-chip battery.

6. The battery cross-section sample preparation method according to claim 1, characterized in that: The battery cell is a dry cell without liquid injection, or a cell that has been charged and discharged.

7. The battery cross-section sample preparation method according to claim 1, characterized in that: When winding the battery cell, the battery cell is wound and sealed as a whole, and no part of the battery cell is exposed.

8. The battery cross-section sample preparation method according to claim 1, characterized in that: The wrapping material is a mixture of resin and curing agent, wherein the mass ratio of the resin to the curing agent is 10:2-3.

9. The battery cross-section sample preparation method according to claim 1, characterized in that: In step S4, low temperature argon ion polishing is performed, and the freezing temperature is ≤-20°C.

10. The battery cross-section sample preparation method according to claim 1, characterized in that: In step S5, before using diamond wire to cut the outer package of the battery cross-section mosaic block, it is necessary to cover and protect the battery cross-section with a blue film.

Images