CN117969577A - Method for detecting metal impurity particles of lithium battery material - Google Patents
Method for detecting metal impurity particles of lithium battery material Download PDFInfo
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- CN117969577A CN117969577A CN202311691442.0A CN202311691442A CN117969577A CN 117969577 A CN117969577 A CN 117969577A CN 202311691442 A CN202311691442 A CN 202311691442A CN 117969577 A CN117969577 A CN 117969577A
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- magnetic rod
- lithium battery
- particles
- impurity particles
- metal impurity
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- 239000002245 particle Substances 0.000 title claims abstract description 51
- 239000012535 impurity Substances 0.000 title claims abstract description 48
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 45
- 239000002184 metal Substances 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 39
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 28
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 28
- 239000000463 material Substances 0.000 title claims abstract description 28
- 239000004033 plastic Substances 0.000 claims abstract description 24
- -1 polytetrafluoroethylene Polymers 0.000 claims abstract description 15
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract description 15
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract description 15
- 239000002904 solvent Substances 0.000 claims abstract description 15
- 238000001514 detection method Methods 0.000 claims abstract description 13
- 238000007789 sealing Methods 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 4
- 239000012528 membrane Substances 0.000 claims description 20
- 230000003749 cleanliness Effects 0.000 claims description 16
- 238000004458 analytical method Methods 0.000 claims description 12
- 239000003292 glue Substances 0.000 claims description 11
- 239000002923 metal particle Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 238000000967 suction filtration Methods 0.000 claims description 7
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 3
- 230000001070 adhesive effect Effects 0.000 claims description 3
- 229910052755 nonmetal Inorganic materials 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 238000010008 shearing Methods 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 238000009210 therapy by ultrasound Methods 0.000 claims description 3
- 230000000007 visual effect Effects 0.000 claims description 2
- 239000000126 substance Substances 0.000 description 7
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 230000010287 polarization Effects 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 238000007431 microscopic evaluation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000012284 sample analysis method Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- Sampling And Sample Adjustment (AREA)
Abstract
The invention relates to the technical field of material detection, in particular to a method for detecting metal impurity particles of a lithium battery material, which comprises the following steps: s1, preparing a sample, namely adding a proper amount of the sample and a solvent into a polytetrafluoroethylene barrel; s2, preparing a magnetic rod, namely using a plastic thin Guan Baofu magnetic rod, and sealing a plastic thin pipe coated with the magnetic rod by using a heat sealing machine; s3, extracting a sample, sealing a polytetrafluoroethylene barrel filled with the sample, a solvent and a magnetic rod, and then placing the sealed polytetrafluoroethylene barrel in a tank grinder for mixing.
Description
Technical Field
The invention relates to the technical field of material detection, in particular to a method for detecting metal impurity particles of a lithium battery material.
Background
In a lithium battery, due to the existence of metal impurity elements Fe, cr, cu, zn and the like, the reduction potential of metal impurity ions is lower than Li+, and the metal impurity ions are often embedded into a negative electrode for reduction and precipitation in the charging process, as the process is carried out, reduced elemental metal is accumulated and enriched in the negative electrode, and when the accumulation is carried out to a certain degree, a hard edge angle can pierce through a diaphragm to cause short circuit in the battery, so that higher self-discharge is caused, and meanwhile, the internal temperature of the battery is increased, so that the safety problem is easy to cause.
Even though metal foreign matters which cannot be found by naked eyes can cause high self-discharge, the internal short circuit of the battery is easy to occur due to the fact that the particle size of the impurities is more than 5 microns, and the metal impurities are the weight of raw materials and process management in the manufacturing of the lithium battery; the current magnetic substance detection method for lithium battery materials in the industry is mainly ICP-OES or ICP-MS, which is used as a qualitative and quantitative multi-element detection analysis method, has the detection limits of PPb and PPt levels, is accurate in detection, has a very mature application scheme in actual mass production, but ICP is subject to the interference of the detection limits and the test process, and is difficult to respond to trace impurity elements; in addition, the ICP is used as a destructive analysis of a sample, can perform qualitative and quantitative analysis, namely 'presence or absence' analysis, and cannot be known about the actual existence state of a detected substance; at present, the short-circuit point of the battery core exists in the forms of metal compounds, alloys and the like, and the accurate tracing of the current testing means is difficult.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides a method for detecting metal impurity particles of a lithium battery material.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the method for detecting the metal impurity particles of the lithium battery material comprises the following steps:
s1, preparing a sample, namely adding a proper amount of the sample and a solvent into a polytetrafluoroethylene barrel;
S2, preparing a magnetic rod, namely using a plastic thin Guan Baofu magnetic rod, sealing a plastic thin pipe coated with the magnetic rod by using a heat sealing machine, and then placing the magnetic rod containing the plastic thin pipe into a polytetrafluoroethylene barrel;
S3, extracting a sample, namely sealing a polytetrafluoroethylene barrel filled with the sample, the solvent and the magnetic rod, placing the sealed polytetrafluoroethylene barrel in a tank mill for mixing, taking out the magnetic rod after finishing, peeling off the plastic thin tube from the magnetic rod, placing the magnetic rod in a clean beaker, adding deionized water, performing ultrasonic treatment by using an ultrasonic cleaner until no residue exists on the plastic thin tube, and taking out the plastic tube from the beaker;
S4, purifying a sample, namely encircling the bottom of the wall of the beaker by using a small magnetic rod, adsorbing and gathering metal particles at the bottom of the beaker, pouring out the solution, and repeating the steps until the solution is clear;
S5, extracting metal particles, mounting filter paper in a suction bottle of a suction filtration device, pouring clarified solution containing the metal particles for suction filtration until no obvious water drops exist on the surface of the filter paper, adding CMC glue solution, and fixing on a slide;
S6, EDS component analysis, namely shearing a filter membrane containing impurity particles, adhering the filter membrane to an EDS objective table by using conductive adhesive, performing metal spraying treatment, and performing EDS component analysis.
Further, the ratio of the sample to the solvent in step S1 is 1:5-1:8.
Further, the solvent is a mixture of deionized water and NMP solution.
Further, the rotation speed of the pot mill in the step S3 is 60 revolutions per minute, and the stirring time is 15 minutes.
Further, the method further comprises a step of positioning particles of the cleanliness analyzer, and after the step S5, the metal impurity particles are positioned by the cleanliness analyzer.
Further, the cleanliness analyzer mainly comprises a microscopic camera and an image processing system, through polarized light secondary scanning, the gray value changes of orthogonal polarized light and parallel polarized light respectively scanning are used for identifying the shape, size, quantity, position and other information of metal particles and nonmetal particles in a sample visual field, a carrier sheet comprising a filter membrane is taken, the cleanliness analyzer is used for identifying and positioning metal impurity particles on the filter membrane, and the positions of the particles on the filter membrane are identified.
And (5) adding CMC glue solution in the step (5) to just cover the surface of the filter paper, and drying the filter paper by a drying device after finishing.
Further, the solid content of CMC glue solution is 0.0025% -0.0045%.
Further, the magnetic field strength of the magnetic rod is 6000GS, the diameter of the magnetic rod is 24mm, and the length of the magnetic rod is 240mm.
Further, the plastic thin tube has a wall thickness of 0.3mm and a diameter of 25mm.
The method for detecting the metal impurity particles of the lithium battery material has the beneficial effects that: the detection method of the metal impurity particles of the lithium battery material mainly comprises the steps of extracting and detecting the metal impurity particles, can effectively and completely identify the existence form of the impurity particles in the lithium battery material, comprises the information of simple substances, compounds or mixtures, element types, morphology and the like, provides direct and accurate positioning for tracing the short-circuit point which affects the self-discharge of the battery cell, namely the metal impurity particles, is complementary with the advantages formed by ICP detection, and has great significance as an important measure for controlling the metal impurities in the current lithium battery production.
Drawings
Fig. 1 is a schematic structural view of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.
Referring to fig. 1, in one embodiment of the present invention, a method for detecting metal impurity particles of a lithium battery material is disclosed, and specifically, the method includes the following steps:
s1, preparing a sample, namely adding a proper amount of the sample and a solvent into a polytetrafluoroethylene barrel;
S2, preparing a magnetic rod, namely using a plastic thin Guan Baofu magnetic rod, sealing a plastic thin pipe coated with the magnetic rod by using a heat sealing machine, and then placing the magnetic rod containing the plastic thin pipe into a polytetrafluoroethylene barrel;
S3, extracting a sample, namely sealing a polytetrafluoroethylene barrel filled with the sample, the solvent and the magnetic rod, and then placing the sealed polytetrafluoroethylene barrel in a tank mill for mixing, wherein the rotating speed of the tank mill is 60 revolutions per minute, the stirring time is 15 minutes, taking out the magnetic rod after the end, peeling off the plastic thin tube from the magnetic rod, placing the plastic thin tube in a clean beaker, adding deionized water, performing ultrasonic treatment by using an ultrasonic cleaner until no residue exists on the plastic thin tube, and taking out the plastic tube from the beaker;
s4, purifying a sample, namely encircling the bottom of the wall of the beaker by using a small magnetic rod, wherein the magnetic field strength of the small magnetic rod is 4000GS, adsorbing and gathering metal particles at the bottom of the beaker, pouring out the solution, and repeating the steps until the solution is clear;
S5, extracting metal particles, mounting filter paper in a suction bottle of a suction filtration device, pouring clarified solution containing the metal particles for suction filtration until no obvious water drops exist on the surface of the filter paper, adding CMC glue solution, and fixing on a slide;
S6, EDS component analysis, namely shearing a filter membrane containing impurity particles, adhering the filter membrane to an EDS objective table by using conductive adhesive, performing metal spraying treatment, and performing EDS component analysis.
In some embodiments, the ratio of the sample to the solvent added in step S1 of the present invention is 1:5-1:8, further, the solvent in this example is a mixture of deionized water and NMP solution, which is a solution containing N-methylpyrrolidone, and NMP is a common organic solvent and has excellent dissolution property and chemical stability.
In addition, the method of the present invention further comprises a step of locating particles of the cleanliness analyzer, after which the metal impurity particles are located by the cleanliness analyzer after said step S5.
Based on the above embodiment, the cleanliness analyzer of the present invention mainly comprises a microscope camera and an image processing system, and recognizes the shape, size, number, position and other information of metal and nonmetal particles in the sample field of view by the gray value changes of the orthogonal polarization and parallel polarization scanning respectively through polarization secondary scanning, takes a slide containing a filter membrane, recognizes and positions the metal impurity particles on the filter membrane by using the cleanliness analyzer, and identifies the positions of the particles on the filter membrane.
In addition, it should be noted that in this embodiment, the CMC glue solution is added in the amount just covering the surface of the filter paper in step S5, and the filter paper is dried by the drying device after the completion of the process.
Specifically, the solid content of CMC glue solution in this embodiment is 0.0025% -0.0045%, CMC effectively solves the problem of sample transfer between the positioning of the cleanliness apparatus and the analysis of EDS components, metal impurities are filtered to a filter membrane, particles are easy to fall off after drying, the particles are positioned by the cleanliness apparatus and are easily lost in the process of transferring to the EDS sample preparation, the glue solution can completely fix impurity particles on the filter membrane after solidification, the success rate of sample transfer is directly raised from 20% to 100%, which has great significance for the integrity of the whole detection method, in addition, CMC as an auxiliary material of lithium battery effectively avoids the risk of reintroducing other variables; the CMC is colorless, so that the analysis process of the cleanliness instrument is not influenced; CMC solid content 0.0025% -0.0045% can ensure certain adhesion force to fix the particles on the filter membrane, and avoid excessive solvent accumulation on the filter membrane caused by over-adhesion.
In this example, the magnetic field strength of the magnetic rod was 6000GS, the diameter thereof was 24mm, the length thereof was 240mm, and the wall thickness of the plastic thin tube was 0.3mm, the diameter thereof was 25mm.
In summary, the method for detecting the metal impurity particles of the lithium battery material mainly comprises the steps of extracting and detecting the metal impurity particles, can effectively and completely identify the existence forms of the impurity particles in the lithium battery material, including simple substances, compounds or mixtures, and information of element types, morphology and the like, provides direct and accurate positioning for tracing a short-circuit point which influences self-discharge of a battery cell, namely the metal impurity particles, is complementary with the advantages formed by ICP detection, and has very important significance as an important measure for controlling the metal impurities in the current lithium battery production.
Secondly, magnetic substances such as Fe, cr and the like in the material can be efficiently extracted by a magnetic rod adsorption method; the cleanliness instrument can realize macroscopic positioning observation, can not perform component analysis and EDS analysis, can perform microscopic analysis, and can not realize macroscopic positioning, so that the advantages and disadvantages are complemented;
By adding CMC glue solution in the suction filtration step, the impurity particles can be completely fixed on the filter membrane after solidification, the success rate of sample transfer is directly increased from 20% to 100%,
The detection method is used as a sample analysis method, can keep the initial state of impurity elements from sample extraction to EDS analysis, can directly know whether the existing state is simple substance, compound or mixture, and has very important significance for tracing and improving metal impurity particles in materials.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (10)
1. The detection method of the metal impurity particles of the lithium battery material is characterized by comprising the following steps of:
s1, preparing a sample, namely adding a proper amount of the sample and a solvent into a polytetrafluoroethylene barrel;
S2, preparing a magnetic rod, namely using a plastic thin Guan Baofu magnetic rod, sealing a plastic thin pipe coated with the magnetic rod by using a heat sealing machine, and then placing the magnetic rod containing the plastic thin pipe into a polytetrafluoroethylene barrel;
S3, extracting a sample, namely sealing a polytetrafluoroethylene barrel filled with the sample, the solvent and the magnetic rod, placing the sealed polytetrafluoroethylene barrel in a tank mill for mixing, taking out the magnetic rod after finishing, peeling off the plastic thin tube from the magnetic rod, placing the magnetic rod in a clean beaker, adding deionized water, performing ultrasonic treatment by using an ultrasonic cleaner until no residue exists on the plastic thin tube, and taking out the plastic tube from the beaker;
S4, purifying a sample, namely encircling the bottom of the wall of the beaker by using a small magnetic rod, adsorbing and gathering metal particles at the bottom of the beaker, pouring out the solution, and repeating the steps until the solution is clear;
S5, extracting metal particles, mounting filter paper in a suction bottle of a suction filtration device, pouring clarified solution containing the metal particles for suction filtration until no obvious water drops exist on the surface of the filter paper, adding CMC glue solution, and fixing on a slide;
S6, EDS component analysis, namely shearing a filter membrane containing impurity particles, adhering the filter membrane to an EDS objective table by using conductive adhesive, performing metal spraying treatment, and performing EDS component analysis.
2. The method for detecting metal impurity particles of lithium battery material according to claim 1, wherein the method comprises the following steps: the addition ratio of the sample to the solvent in the step S1 is 1:5-1:8.
3. The method for detecting metal impurity particles of lithium battery material according to claim 2, wherein the method comprises the following steps: the solvent is a mixture of deionized water and NMP solution.
4. The method for detecting metal impurity particles of lithium battery material according to claim 1, wherein the method comprises the following steps: and S3, the rotating speed of the tank grinder is 60 revolutions per minute, and the stirring time is 15 minutes.
5. The method for detecting metal impurity particles of lithium battery material according to claim 1, wherein the method comprises the following steps: and the method also comprises a step of positioning particles of the cleanliness analyzer, wherein after the step S5, the metal impurity particles are positioned by the cleanliness analyzer.
6. The method for detecting metal impurity particles of lithium battery material according to claim 5, wherein the method comprises the following steps: the cleanliness analyzer mainly comprises a microscopic camera and an image processing system, the shape, the size, the number, the position and other information of metal and nonmetal particles in a sample visual field are identified through polarized light secondary scanning and gray value changes of orthogonal polarized light and parallel polarized light respectively scanning, a carrier sheet containing a filter membrane is taken, metal impurity particles on the filter membrane are identified and positioned by the cleanliness analyzer, and the positions of the particles on the filter membrane are identified.
7. The method for detecting metal impurity particles of lithium battery material according to claim 5, wherein the method comprises the following steps: and S5, adding the CMC glue solution to just cover the surface of the filter paper, and drying the filter paper by a drying device after finishing.
8. The method for detecting metal impurity particles of lithium battery material according to claim 1, 5,6 or 7, wherein the method comprises the steps of: the solid content of CMC glue solution is 0.0025% -0.0045%.
9. The method for detecting metal impurity particles of lithium battery material according to claim 1, wherein the method comprises the following steps: the magnetic field strength of the magnetic rod is 6000GS, the diameter of the magnetic rod is 24mm, and the length of the magnetic rod is 240mm.
10. The method for detecting metal impurity particles of lithium battery material according to claim 1, wherein the method comprises the following steps: the plastic thin tube has a wall thickness of 0.3mm and a diameter of 25mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311691442.0A CN117969577A (en) | 2023-12-11 | 2023-12-11 | Method for detecting metal impurity particles of lithium battery material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311691442.0A CN117969577A (en) | 2023-12-11 | 2023-12-11 | Method for detecting metal impurity particles of lithium battery material |
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| Publication Number | Publication Date |
|---|---|
| CN117969577A true CN117969577A (en) | 2024-05-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311691442.0A Pending CN117969577A (en) | 2023-12-11 | 2023-12-11 | Method for detecting metal impurity particles of lithium battery material |
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| Country | Link |
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| CN (1) | CN117969577A (en) |
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2023
- 2023-12-11 CN CN202311691442.0A patent/CN117969577A/en active Pending
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