CN113804799A - A kind of pretreatment method and method for testing NMP content in lithium ion battery pole piece - Google Patents
A kind of pretreatment method and method for testing NMP content in lithium ion battery pole piece Download PDFInfo
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- CN113804799A CN113804799A CN202111240079.1A CN202111240079A CN113804799A CN 113804799 A CN113804799 A CN 113804799A CN 202111240079 A CN202111240079 A CN 202111240079A CN 113804799 A CN113804799 A CN 113804799A
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 53
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000012360 testing method Methods 0.000 title claims abstract description 40
- 238000002203 pretreatment Methods 0.000 title claims abstract description 19
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 132
- 238000002414 normal-phase solid-phase extraction Methods 0.000 claims abstract description 56
- 238000001914 filtration Methods 0.000 claims abstract description 21
- 239000007788 liquid Substances 0.000 claims abstract description 20
- 238000000605 extraction Methods 0.000 claims abstract description 15
- 239000012528 membrane Substances 0.000 claims abstract description 13
- 238000005520 cutting process Methods 0.000 claims abstract description 9
- 238000001514 detection method Methods 0.000 claims abstract description 9
- 239000000706 filtrate Substances 0.000 claims abstract description 8
- 238000004458 analytical method Methods 0.000 claims description 15
- 238000004817 gas chromatography Methods 0.000 claims description 13
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 11
- 239000011248 coating agent Substances 0.000 claims description 10
- 238000009210 therapy by ultrasound Methods 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- 239000006228 supernatant Substances 0.000 claims description 7
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 6
- 239000003153 chemical reaction reagent Substances 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 2
- -1 polyethylene Polymers 0.000 claims description 2
- 229920000573 polyethylene Polymers 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 claims description 2
- 239000007790 solid phase Substances 0.000 claims description 2
- 239000012086 standard solution Substances 0.000 claims description 2
- 241000083547 Columella Species 0.000 claims 1
- 238000007796 conventional method Methods 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 35
- 239000000243 solution Substances 0.000 description 18
- 239000011521 glass Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000011084 recovery Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000011149 active material Substances 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 239000000741 silica gel Substances 0.000 description 4
- 229910002027 silica gel Inorganic materials 0.000 description 4
- 238000004506 ultrasonic cleaning Methods 0.000 description 4
- 239000013543 active substance Substances 0.000 description 3
- 239000012491 analyte Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 238000000638 solvent extraction Methods 0.000 description 3
- 238000002604 ultrasonography Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 229910018060 Ni-Co-Mn Inorganic materials 0.000 description 2
- 229910018209 Ni—Co—Mn Inorganic materials 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 1
- 239000006255 coating slurry Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000000769 gas chromatography-flame ionisation detection Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012074 organic phase Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N2030/062—Preparation extracting sample from raw material
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
本发明公开一种用于测试锂离子电池极片中NMP含量的前处理方法，涉及锂离子电池极片中NMP含量的测试技术领域，本发明包括以下步骤：(1)将锂离子电池极片裁剪后置于甲醇中，密封后超声处理，静置并冷却至室温；(2)将填充有筛板与有机滤膜的固相萃取小柱预洗，取萃取液加入固相萃取小柱，过滤后收集滤液。本发明还提供用于测试锂离子电池极片中NMP含量的方法。本发明的有益效果在于：本发明可以解决萃取液过滤过程中耗时久、费力等缺点，解决了常规方法导致的测试不准确性问题，经加标测试监测，本发明前处理方法最终获得回收率范围为：92.17％～103.26％，因此检测结果可靠。The invention discloses a pretreatment method for testing NMP content in a lithium ion battery pole piece, and relates to the technical field of testing the NMP content in a lithium ion battery pole piece. The invention includes the following steps: (1) testing the lithium ion battery pole piece After cutting, put it in methanol, seal it, ultrasonically treat it, let it stand, and cool it to room temperature; (2) pre-wash the solid-phase extraction cartridge filled with sieve plates and organic filter membranes, take the extract and add it to the solid-phase extraction cartridge, The filtrate was collected after filtration. The invention also provides a method for testing the NMP content in the pole piece of the lithium ion battery. The beneficial effects of the present invention are as follows: the present invention can solve the shortcomings such as time-consuming and laborious in the extraction liquid filtration process, and solve the problem of inaccuracy of testing caused by conventional methods. The rate range is: 92.17% to 103.26%, so the detection results are reliable.
Description
Technical Field
The invention relates to the technical field of testing of NMP content in a lithium ion battery pole piece, in particular to a pretreatment method and a pretreatment method for testing the NMP content in the lithium ion battery pole piece.
Background
In recent years, the energy crisis has exploded, and global environmental pollution is serious, so that the search and development of alternative energy sources are urgent. The lithium ion battery is widely concerned by society due to the advantages of high voltage, no memory effect, small environmental pollution and the like, and mainly comprises three parts of an electrode, an electrolyte and a diaphragm, wherein the most important part is the electrode. The electrode mainly comprises active substances and a conductive framework, the positive and negative active substances are the sources of the electric energy of the lithium ion battery, and the active material coating slurry generally comprises active materials, a binder, a solvent and the like. Because N-methyl pyrrolidone (NMP) has good solubility, the coating substance of the pole piece active material can be well dissolved, so as to ensure the uniform coating of the active substance. However, NMP does not participate in the normal operation of the battery during the subsequent charging and discharging of the battery, and the existence of NMP even causes the deterioration of the cycle performance of the battery and the reduction of the safety. Therefore, after the active material is uniformly coated on the surface of the polar fluid through the coating process, NMP needs to be removed before entering the next process so as to avoid the NMP remaining on the pole piece, the removal method usually adopted is baking, the NMP can be volatilized through high-temperature baking, but in order to confirm the baking effect, the coated and rolled pole piece needs to be analyzed, and the NMP in the pole piece is quantified so as to ensure the quality of the subsequent battery finished product.
The general procedures for detecting the content of NMP in the existing pole piece are as follows: weighing, extracting, filtering and detecting. The traditional filtration adopts a mode of combining a syringe and a filter head, but the filtration mode is labor-consuming and time-consuming, and only a single sample can be filtered at a time, so that the efficiency is low. In addition, for example, patent publication No. CN104535689A discloses a gas chromatography method for detecting the content of N-methylpyrrolidone in a lithium ion battery electrode sheet, which comprises extracting an extract solution above a triangular flask with a stopper by using an injector, and filtering the extract solution through an organic phase filter membrane. If a plurality of samples need to be processed by the method, a long container needs to be repeatedly cleaned and dried, the consumed time is too long, and timely test results are not easy to obtain. Most importantly, the time consumed in the filtering process usually makes the NMP test result smaller, so that the analysis result is distorted, and finally misjudgment and missed judgment of the problem pole piece are caused, so that the problem battery is easily caused, the production cost is wasted, and even more serious safety problems are caused.
Disclosure of Invention
The invention aims to solve the technical problems that the pretreatment method in the prior art is low in efficiency and usually causes a small NMP test result, and provides a pretreatment method and a method for testing the NMP content in a lithium ion battery pole piece.
The invention solves the technical problems through the following technical means:
a pretreatment method for testing the content of NMP in a lithium ion battery pole piece comprises the following steps:
(1) cutting a lithium ion battery pole piece, placing the cut lithium ion battery pole piece in methanol, sealing, performing ultrasonic treatment, standing and cooling to room temperature;
(2) and (2) placing the solid-phase extraction column filled with the sieve plate and tiled with the organic filter membrane on a solid-phase extractor, pre-washing the solid-phase extraction column, adding the supernatant of the extraction liquid obtained in the step (1) into the pre-washed solid-phase extraction column, filtering and collecting filtrate.
Has the advantages that: the invention can solve the defects of long time consumption, labor waste and the like in the filtering process of the extraction liquid, adopts a solid phase extraction instrument in the filtering process, can process more than ten samples at the same time, solves the problem of inaccurate test caused by the conventional method while efficiently obtaining the extraction liquid, and finally obtains the recovery rate range after the detection by adopting the pretreatment method of the invention through the standard adding test monitoring: 92.17% -103.26%, therefore the detection result is reliable.
The invention can obtain the target analyte solution through the sieve plate and the organic filter membrane in the solid-phase extraction column without loading a solid-phase extraction filler.
The method takes methanol as an extracting agent, has low cost, does not introduce moisture, and does not cause harm to a gas chromatography system when the pre-treated filtrate is used for gas chromatography; the purpose of ultrasound is to increase the speed of solvent extraction of the target in the sample.
Preferably, the lithium ion battery pole piece is a lithium ion battery positive pole piece, and the lithium ion battery positive pole piece comprises a lithium iron phosphate positive coating pole piece, a lithium iron phosphate positive rolling pole piece, a nickel-cobalt-manganese ternary positive coating pole piece or a nickel-cobalt-manganese ternary positive rolling pole piece.
Preferably, the lithium ion battery pole pieces are cut into 0.5 x 0.5cm samples.
Preferably, the ultrasonic treatment power is 350W, the ultrasonic power range is 75-85%, and the ultrasonic time is 90 min.
Has the advantages that: too long ultrasonic time or too high power can cause volatilization of the target in the sample, and too short ultrasonic time or too low power can cause incomplete extraction of the target in the sample.
Preferably, the ratio of the mass of the lithium ion battery pole piece to the volume of the methanol is 0.9-1.1g:10 mL.
Preferably, the sieve plate is matched with the solid phase extraction column in size and is made of polyethylene.
Preferably, the solid phase extraction cartridge should be pre-washed with methanol prior to loading the extract.
A method for testing the content of NMP in a lithium ion battery pole piece comprises the following steps:
(1) cutting a lithium ion battery pole piece, placing the cut lithium ion battery pole piece in methanol, sealing, performing ultrasonic treatment, standing and cooling to room temperature;
(2) and (2) placing the solid-phase extraction column filled with the sieve plate and tiled with the organic filter membrane on a solid-phase extraction instrument, pre-washing the solid-phase extraction column, adding the supernatant of the extraction liquid obtained in the step (1) into the pre-washed solid-phase extraction column, filtering, collecting filtrate, and performing gas chromatography analysis and detection.
Has the advantages that: the invention solves the problem of inaccurate test caused by the conventional method, and the recovery rate range finally obtained by the method is as follows through the standard adding test monitoring: 92.17% -103.26%, therefore the detection result is reliable.
The invention can obtain the target analyte solution through the sieve plate and the organic filter membrane in the solid-phase extraction column without loading a solid-phase extraction filler.
The invention can solve the defects of long time consumption, labor waste and the like in the filtering process of the extraction liquid, and can simultaneously process more than ten samples by adopting the solid phase extraction instrument in the filtering process.
The method takes methanol as an extracting agent, has low cost, does not introduce moisture, and does not cause harm to a gas chromatography system when the pre-treated filtrate is used for gas chromatography; the purpose of ultrasound is to increase the speed of solvent extraction of the target in the sample.
Preferably, the liquid outlet of the solid phase extraction column is positioned in a centrifugal tube, and the centrifugal tube is positioned in a vacuum groove.
Preferably, the method further comprises a blank reagent preparation step: 10mL of methanol was sealed.
Preferably, the method further comprises the following step of standard sample configuration: weighing samples, adding NMP standard solution with known concentration to different sample adding amounts, adding pure methanol to make the total volume 10mL, and sealing.
Preferably, the sample to be tested and the spiked sample are treated in parallel three times.
The invention has the advantages that: the invention can solve the defects of long time consumption, labor waste and the like in the filtering process of the extraction liquid, adopts a solid phase extraction instrument in the filtering process, can process more than ten samples at the same time, solves the problem of inaccurate test caused by the conventional method while efficiently obtaining the extraction liquid, and finally obtains the recovery rate range after the detection by adopting the pretreatment method of the invention through the standard adding test monitoring: 92.17% -103.26%, therefore the detection result is reliable.
The invention can obtain the target analyte solution through the sieve plate and the organic filter membrane in the solid-phase extraction column without loading a solid-phase extraction filler.
The method takes methanol as an extracting agent, has low cost, does not introduce moisture, and does not cause harm to a gas chromatography system when the pre-treated filtrate is used for gas chromatography; the purpose of ultrasound is to increase the speed of solvent extraction of the target in the sample.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.
In the following examples, the detection instrument used was a GC-FID gas chromatography-hydrogen flame detector.
Example 1
The method for testing the content of NMP in the lithium ion battery pole piece specifically comprises the following steps:
(1) coating a lithium iron phosphate positive electrode of a lithium ion battery with a pole piece, and cutting a sample with the size of 0.5 multiplied by 0.5cm in the middle area of the pole piece to be detected.
(2) 9 samples (1.0. + -. 0.1 g) were weighed into 9 20mL screw-pretreated glass vials, 10mL of methanol was added to 3 samples, and the vials were sealed. To 3 additional samples, 0.6mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. To the remaining 3 samples, 1mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. Finally, another screw-top pre-treated glass vial was taken, 10mL of methanol was added thereto, and the vial was sealed. And (3) placing the sealed pre-treated vial in an ultrasonic cleaning machine, extracting for 90min at the power of 350 multiplied by 80%, standing after the ultrasonic treatment is finished, and cooling to room temperature. Wherein. + -. 0.1g indicates an error.
(3) The height of the test tube rack in the groove of the solid phase extraction instrument is adjusted, 20 centrifuge tubes with proper specifications are placed, and all channels are closed through a flow regulating valve. Placing 1mL of solid-phase extraction column provided with a sieve plate and an organic filter membrane on a column frame, ensuring that the solid-phase extraction column is placed at the corresponding position of a centrifuge tube in a groove, and pre-washing the solid-phase extraction column by using 1mL of methanol for three times. The solid phase extraction apparatus is the prior art.
(4) And placing the solid-phase extraction small column at a position corresponding to another empty centrifugal tube in the tank, connecting the other end of the silica gel tube connected with the vacuum tank to a vacuum pump, opening a channel where the sample is located, immediately transferring 0.5mL of the extract obtained from the pretreatment small column into the solid-phase extraction small column for extract filtration, collecting the filtered liquid, and immediately performing gas chromatography component analysis on the filtered liquid.
A chromatographic column: DB-WAX, 30m,0.25mm,0.25 μm; sample injector temperature: 260 ℃, detector temperature: 300 ℃, column temperature: maintaining at 100 deg.C for 1min, heating to 210 deg.C at 10 deg.C/min, and maintaining at 210 deg.C for 2 min.
In the extraction process, the opening and closing of each channel and the extraction speed can be independently controlled, and the sample extraction liquid is timely treated due to high extraction efficiency.
The analysis results are shown in table 1, and according to the analysis results, the method is suitable for detecting NMP in the lithium ion battery pole piece, and the battery lithium iron phosphate positive electrode coating pole piece meets the process standard.
TABLE 1 determination results of lithium iron phosphate positive electrode coating pole pieces and recovery by adding standard
Example 2
The method for testing the content of NMP in the lithium ion battery pole piece specifically comprises the following steps:
(1) taking a lithium iron phosphate positive electrode of the lithium ion battery to roll the pole piece, and cutting a sample with the size of 0.5 multiplied by 0.5cm in the middle area of the pole piece to be measured.
(2) 9 samples (1.0. + -. 0.1 g) were weighed into 9 20mL screw-pretreated glass vials, 10mL of methanol was added to 3 samples, and the vials were sealed. To 3 additional samples, 0.6mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. To the remaining 3 samples, 1mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. Finally, another screw-top pre-treated glass vial was taken, 10mL of methanol was added thereto, and the vial was sealed. And (3) placing the sealed pre-treated vial in an ultrasonic cleaning machine, extracting for 90min at the power of 350 multiplied by 80%, standing after the ultrasonic treatment is finished, and cooling to room temperature.
(3) The height of the test tube rack in the groove of the solid phase extraction instrument is adjusted, 20 centrifuge tubes with proper specifications are placed, and all channels are closed through a flow regulating valve. Placing 1mL of solid-phase extraction column provided with a sieve plate and an organic filter membrane on a column frame, ensuring that the solid-phase extraction column is placed at the corresponding position of a centrifuge tube in a groove, and pre-washing the solid-phase extraction column by using 1mL of methanol for three times.
(4) And placing the solid-phase extraction small column at a position corresponding to another empty centrifugal tube in the tank, connecting the other end of the silica gel tube connected with the vacuum tank to a vacuum pump, opening a channel where the sample is located, immediately transferring 0.5mL of extract supernatant obtained in the pre-treatment small column to the solid-phase extraction small column for extract filtration, collecting filtered liquid, and immediately performing gas chromatography component analysis on the filtered liquid.
The analysis results are shown in table 2, and according to the analysis results, the method is suitable for detecting NMP in the lithium ion battery pole piece, and the battery lithium iron phosphate positive electrode rolled pole piece meets the process standard.
TABLE 2 determination results of rolled pole pieces of lithium iron phosphate positive electrode and recovery of the rolled pole pieces by adding a standard
Example 3
The method for testing the content of NMP in the lithium ion battery pole piece specifically comprises the following steps:
(1) taking a nickel-cobalt-manganese ternary positive electrode of the lithium ion battery to coat a pole piece, and cutting a sample with the size of 0.5 multiplied by 0.5cm in the middle area of the pole piece to be measured.
(2) 9 samples (1.0. + -. 0.1 g) were weighed into 9 20mL screw-pretreated glass vials, 10mL of methanol was added to 3 samples, and the vials were sealed. To 3 additional samples, 0.6mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. To the remaining 3 samples, 1mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. Finally, another screw-top pre-treated glass vial was taken, 10mL of methanol was added thereto, and the vial was sealed. And (3) placing the sealed pre-treated vial in an ultrasonic cleaning machine, extracting for 90min at the power of 350 multiplied by 80%, standing after the ultrasonic treatment is finished, and cooling to room temperature.
(3) The height of the test tube rack in the groove of the solid phase extraction instrument is adjusted, 20 centrifuge tubes with proper specifications are placed, and all channels are closed through a flow regulating valve. Placing 1mL of solid-phase extraction column provided with a sieve plate and an organic filter membrane on a column frame, ensuring that the solid-phase extraction column is placed at the corresponding position of a centrifuge tube in a groove, and pre-washing the solid-phase extraction column by using 1mL of methanol for three times.
(4) And placing the solid-phase extraction small column at a position corresponding to another empty centrifugal tube in the tank, connecting the other end of the silica gel tube connected with the vacuum tank to a vacuum pump, opening a channel where the sample is located, immediately transferring 0.5mL of extract supernatant obtained in the pre-treatment small column to the solid-phase extraction small column for extract filtration, collecting filtered liquid, and immediately performing gas chromatography component analysis on the filtered liquid.
The analysis results are shown in table 3 and table 2, and according to the analysis results, the method is suitable for detecting NMP in the lithium ion battery pole piece and judging that the battery lithium iron phosphate positive pole rolled pole piece meets the process standard.
TABLE 3 measurement results of Ni-Co-Mn ternary positive electrode coating and standard recovery
Example 4
The method for testing the content of NMP in the lithium ion battery pole piece specifically comprises the following steps:
(1) taking a nickel-cobalt-manganese ternary positive electrode rolling pole piece of the lithium ion battery, and cutting a sample with the size of 0.5 multiplied by 0.5cm in the middle area of the pole piece to be measured.
(2) 9 samples (1.0. + -. 0.1 g) were weighed into 9 20mL screw-pretreated glass vials, 10mL of methanol was added to 3 samples, and the vials were sealed. To 3 additional samples, 0.6mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. To the remaining 3 samples, 1mL of 5000ppm NMP solution (dissolved in methanol) was added, and the mixture was made up to a total volume of 10mL with methanol and sealed. Finally, another screw-top pre-treated glass vial was taken, 10mL of methanol was added thereto, and the vial was sealed. And (3) placing the sealed pre-treated vial in an ultrasonic cleaning machine, extracting for 90min at the power of 350 multiplied by 80%, standing after the ultrasonic treatment is finished, and cooling to room temperature.
(3) The height of the test tube rack in the groove of the solid phase extraction instrument is adjusted, 20 centrifuge tubes with proper specifications are placed, and all channels are closed through a flow regulating valve. Placing 1mL of solid-phase extraction column provided with a sieve plate and an organic filter membrane on a column frame, ensuring that the solid-phase extraction column is placed at the corresponding position of a centrifuge tube in a groove, and pre-washing the solid-phase extraction column by using 1mL of methanol for three times.
(4) And placing the solid-phase extraction small column at a position corresponding to another empty centrifugal tube in the tank, connecting the other end of the silica gel tube connected with the vacuum tank to a vacuum pump, opening a channel where the sample is located, immediately transferring 0.5mL of extract supernatant obtained in the pre-treatment small column to the solid-phase extraction small column for extract filtration, collecting filtered liquid, and immediately performing gas chromatography component analysis on the filtered liquid.
The analysis results are shown in table 4 and table 2, and according to the analysis results, the method is suitable for detecting NMP in the lithium ion battery pole piece and judging that the battery lithium iron phosphate positive pole rolled pole piece meets the process standard.
TABLE 4 measurement results of Ni-Co-Mn ternary positive rolled pole piece and standard recovery
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A pretreatment method for testing the content of NMP in a lithium ion battery pole piece is characterized in that: the method comprises the following steps:
(1) cutting a lithium ion battery pole piece, placing the cut lithium ion battery pole piece in methanol, sealing, performing ultrasonic treatment, standing and cooling to room temperature;
(2) and (2) placing the solid-phase extraction column filled with the sieve plate and tiled with the organic filter membrane on a solid-phase extractor, pre-washing the solid-phase extraction column, adding the supernatant of the extraction liquid obtained in the step (1) into the pre-washed solid-phase extraction column, filtering and collecting filtrate.
2. The pretreatment method for testing the content of NMP in the lithium ion battery pole piece according to claim 1, characterized in that: the lithium ion battery pole piece is a lithium ion battery anode pole piece, and the lithium ion battery anode pole piece comprises a lithium iron phosphate anode coating pole piece, a lithium iron phosphate anode rolled pole piece, a nickel-cobalt-manganese ternary anode coating pole piece or a nickel-cobalt-manganese ternary anode rolled pole piece.
3. The pretreatment method for testing the content of NMP in the lithium ion battery pole piece according to claim 1, characterized in that: the ultrasonic treatment power is 350W, the ultrasonic power range is 75-85%, and the ultrasonic time is 90 min.
4. The pretreatment method for testing the content of NMP in the lithium ion battery pole piece according to claim 1, characterized in that: the ratio of the mass of the lithium ion battery pole piece to the volume of the methanol is 0.9-1.1g:10 mL.
5. The pretreatment method for testing the content of NMP in the lithium ion battery pole piece according to claim 1, characterized in that: the sieve plate is matched with the solid phase extraction column in size and is made of polyethylene.
6. The pretreatment method for testing the content of NMP in the lithium ion battery pole piece according to claim 1, characterized in that: the solid phase extraction cartridge should be pre-washed with methanol before the extract is loaded.
7. A method for testing the content of NMP in a lithium ion battery pole piece is characterized in that: the method comprises the following steps:
(1) cutting a lithium ion battery pole piece, placing the cut lithium ion battery pole piece in methanol, sealing, performing ultrasonic treatment, standing and cooling to room temperature;
(2) and (2) placing the solid-phase extraction column filled with the sieve plate and tiled with the organic filter membrane on a solid-phase extraction instrument, pre-washing the solid-phase extraction column, adding the supernatant of the extraction liquid obtained in the step (1) into the pre-washed solid-phase extraction column, filtering, collecting filtrate, and performing gas chromatography analysis and detection.
8. The method for testing the content of NMP in the lithium ion battery pole piece according to claim 7, characterized in that: the mouth of the solid phase extraction columella is positioned in a centrifuge tube which is positioned in a vacuum groove.
9. The method for testing the content of NMP in the lithium ion battery pole piece according to claim 7, characterized in that: further comprises a blank reagent preparation step: 10mL of methanol was sealed.
10. The method for testing the content of NMP in the lithium ion battery pole piece according to claim 7, characterized in that: further comprises a step of standard sample adding configuration: weighing samples, adding NMP standard solution with known concentration to reach different sample adding amounts, adding pure methanol to make the total volume be 10mL, and sealing.
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