CN113686801A - Method for measuring water absorption capacity of lithium-ion battery electrolyte based on infrared spectroscopy - Google Patents
Method for measuring water absorption capacity of lithium-ion battery electrolyte based on infrared spectroscopy Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 100
- 239000003792 electrolyte Substances 0.000 title claims abstract description 87
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 83
- 229910001868 water Inorganic materials 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000004566 IR spectroscopy Methods 0.000 title claims abstract description 18
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title abstract description 7
- 229910001416 lithium ion Inorganic materials 0.000 title abstract description 7
- 238000002835 absorbance Methods 0.000 claims abstract description 61
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 42
- 238000005259 measurement Methods 0.000 claims abstract description 13
- FYSNRJHAOHDILO-UHFFFAOYSA-N thionyl chloride Substances ClS(Cl)=O FYSNRJHAOHDILO-UHFFFAOYSA-N 0.000 claims description 59
- 229910006124 SOCl2 Inorganic materials 0.000 claims description 47
- 239000008367 deionised water Substances 0.000 claims description 30
- 229910021641 deionized water Inorganic materials 0.000 claims description 30
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical group [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 27
- 229910052740 iodine Inorganic materials 0.000 claims description 27
- 239000011630 iodine Substances 0.000 claims description 27
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 claims description 18
- 238000011049 filling Methods 0.000 claims description 10
- 239000010453 quartz Substances 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 238000002347 injection Methods 0.000 claims description 8
- 239000007924 injection Substances 0.000 claims description 8
- 238000005070 sampling Methods 0.000 claims description 6
- 230000003595 spectral effect Effects 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 238000007789 sealing Methods 0.000 claims description 5
- 238000012360 testing method Methods 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 2
- 238000000691 measurement method Methods 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 3
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 11
- 238000002329 infrared spectrum Methods 0.000 description 6
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- KPZGRMZPZLOPBS-UHFFFAOYSA-N 1,3-dichloro-2,2-bis(chloromethyl)propane Chemical compound ClCC(CCl)(CCl)CCl KPZGRMZPZLOPBS-UHFFFAOYSA-N 0.000 description 1
- JFBZPFYRPYOZCQ-UHFFFAOYSA-N [Li].[Al] Chemical compound [Li].[Al] JFBZPFYRPYOZCQ-UHFFFAOYSA-N 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910001537 lithium tetrachloroaluminate Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3554—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for determining moisture content
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3577—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing liquids, e.g. polluted water
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N2021/3595—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using FTIR
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Abstract
The invention provides a method for measuring the water absorption capacity of lithium-ion battery electrolyte based on infrared spectroscopy, which comprises the following steps: preparing at least three groups of standard samples of lithium subcell electrolyte, respectively measuring absorbance values of different standard samples through infrared spectroscopy, and fitting to obtain a fitting curve equation of absorbance and water absorption capacity; and measuring the absorbance of the sample to be measured by an infrared spectroscopy, and substituting the absorbance into a fitting curve equation to obtain the water absorption capacity of the sample to be measured. The invention has the advantages of accurate detection result and small error, can quantitatively measure the water absorption capacity of the electrolyte and effectively solves the problems of low efficiency and low precision of electrolyte moisture measurement.
Description
Technical Field
The invention belongs to the technical field of lithium secondary batteries, relates to the water absorption capacity of electrolyte of a lithium secondary battery, and particularly relates to a method for measuring the water absorption capacity of the electrolyte of the lithium secondary battery based on infrared spectroscopy.
Background
The lithium/thionyl chloride energy type battery has higher specific energy and working voltage, and meanwhile, the working temperature range is extremely wide, the annual self-discharge rate is extremely low, so that the lithium/thionyl chloride energy type battery is increasingly applied to the fields of intelligent instruments, petroleum drilling, intelligent tracking, ETC, national defense and the like in more than ten years.
In the manufacturing process of the lithium subcell, raw materials such as metallic lithium, thionyl chloride, tetrachloroaluminum lithium and the like are easy to absorb moisture in the environment and react with water, and the introduced moisture can damage the cell greatly, cause serious lag of the cell, consume active substances and reduce the cell capacity. Therefore, moisture control is highly important in the battery manufacturing process. For example, the materials such as the positive electrode and the separator are baked at a high temperature to remove water before assembling the battery, and the dew point value is reduced to-40 ℃ or lower by controlling the environmental humidity during assembling.
At present, mature instruments and methods are available for measuring the moisture content of materials such as a separator, a positive electrode and the like, but the moisture content measurement of a lithium sub-electrolyte is difficult and serious. The method for measuring the water absorption capacity of the electrolyte is mainly characterized in that a lithium belt with a smooth and clean surface is placed in the electrolyte, the surface color of the lithium belt is observed after a period of time, if the color of the lithium belt is black, the fact that water in the electrolyte reacts with the lithium belt is indicated, the water absorption capacity of the electrolyte is unqualified, and otherwise, if the lithium belt is still smooth, the water absorption capacity of the electrolyte is qualified.
The measurement of the water absorption of the lithium sub-electrolyte still has the problems of large subjective factor and low accuracy, and the quantitative problem of the water absorption is still a key concern, so that a method for accurately measuring the water absorption of the electrolyte is urgently needed.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for measuring the water absorption capacity of the lithium-ion battery electrolyte based on infrared spectroscopy, which can accurately and quantitatively detect the water absorption capacity of the electrolyte and has higher stability and reliability.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for measuring the water absorption capacity of lithium-ion battery electrolyte based on infrared spectroscopy, which comprises the following steps:
preparing at least three groups of standard samples of lithium subcell electrolyte, respectively measuring absorbance values of different standard samples through infrared spectroscopy, and fitting to obtain a fitting curve equation of absorbance and water absorption capacity; and measuring the absorbance of the sample to be measured by an infrared spectroscopy, and substituting the absorbance into a fitting curve equation to obtain the water absorption capacity of the sample to be measured.
As a preferred embodiment of the present invention, the preparation process of the standard sample specifically includes:
and taking at least three equal parts of lithium sub-battery electrolyte, and adding deionized water with different volumes into each part of lithium sub-battery electrolyte to obtain a standard sample.
Preferably, the standard sample is numbered.
Preferably, the volume of the added deionized water increases in a gradient.
Preferably, the gradient difference is 5 to 15 μ L, for example, 5 μ L, 6 μ L, 7 μ L, 8 μ L, 9 μ L, 10 μ L, 11 μ L, 12 μ L, 13 μ L, 14 μ L or 15 μ L, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the electrolyte of the lithium subcell is taken as six parts of the same amount.
Preferably, 0. mu.L, 5. mu.L, 10. mu.L, 20. mu.L, 30. mu.L and 40. mu.L of deionized water are added to the six lithium subcell electrolytes, respectively.
It should be noted that in the present invention, known amounts of deionized water are respectively injected into iodine vials containing an electrolyte to obtain standard samples, wherein the electrolyte itself contains a certain amount of moisture, so as to facilitate fitting a curve equation and improve accuracy, an original moisture content of the electrolyte may be set as an unknown number a, and on this basis, a known amount of deionized water is respectively added to the electrolyte in each iodine vial, so that a water absorption amount of the standard sample in each iodine vial is a + added amount of deionized water, and an intercept is displayed by obtaining a fitting curve equation after infrared spectrum scanning, so that the intercept value is the original moisture content of the electrolyte.
As a preferred embodiment of the present invention, said lithiumThe electrolyte of the sub-battery is pure SOCl2Or formulated LiA1Cl4/SOCl2And (3) an electrolyte.
Preferably, the water absorption is pure SOCl2Or formulated LiA1Cl4/SOCl2The sum of the original water content in the electrolyte and the added deionized water.
In the invention, the raw materials of the electrolyte are thionyl chloride and lithium aluminum tetrachloride, which are very easy to absorb moisture in the environment, and react with water as follows:
LiAlCl4→AlCl3+LiCl
AlCl3+H2O→LiCl3OH-+HCl
AlCl3OH-+SOCl2→AlCl3+SO2+HCl
SOCl2+H2O→SO2+2HCl
wherein AlCl3OH-And HCl at 3370cm in the IR spectrum-1And 2780cm-1There is a characteristic absorption peak, as shown in FIG. 1. As can be seen from the above reaction equation, for the case where LiA1Cl is not added4Pure SOCl of2The infrared spectrum is used to directly measure the absorbance of HCl, so as to obtain the concentration of HCl in thionyl chloride, and then the amount of absorbed moisture is calculated. For already formulated LiA1Cl4/SOCl2Electrolyte solution, the AlCl must be considered at the same time3OH-And HCl. From the equation, AlCl can be seen3OH-While decreasing, the HCl content increased, but AlCl3OH-The total conversion to HCl takes a long time, and the water uptake of the electrolyte can be increased from AlCl before the total conversion to HCl takes place3OH-And the absorbance of the characteristic peak of HCl.
I.e. pure SOCl2The standard sample is only subjected to infrared spectrum scanning to obtain an HCl characteristic absorption peak, and a fitting curve equation of water absorption and absorbance is fitted by adopting an absorbance value corresponding to the characteristic absorption peak; and the prepared LiA1Cl4/SOCl2Standard samples of electrolyte were scanned by external spectroscopy to obtain HCl and AlCl3OH-And fitting the two characteristic absorption peaks to obtain two fitting curve equations of water absorption and absorbance by respectively adopting the absorbance values corresponding to the characteristic absorption peaks.
Preferably, the lithium sub-battery electrolyte is taken into a containing container.
Preferably, the container is an iodine measuring bottle.
Preferably, the sampling of the lithium subcell electrolyte is performed in a glove box filled with dry air.
Preferably, the relative humidity inside the glove box is < 2%.
As a preferred technical scheme of the invention, a sample injection needle is adopted to respectively add deionized water into an iodine measuring flask.
Preferably, the sampling needle is a dry micro sampling needle.
Preferably, the needle head of the sample injection needle extends into the iodine measuring flask below the liquid level to add the deionized water.
As a preferred technical scheme, the iodine measuring flask is sufficiently shaken after the deionized water is added, so that the electrolyte of the lithium secondary battery and the deionized water are uniformly mixed.
Preferably, the iodine measuring flask after being uniformly mixed is kept still for full reaction.
Preferably, the reaction time is 1.5 to 4 hours, for example, 1.5 hours, 1.7 hours, 2 hours, 2.3 hours, 2.5 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours or 4 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferred technical solution of the present invention, the infrared spectroscopy measurement method specifically includes:
and filling the sample cell of the quartz window with the standard sample, sealing and placing on a Fourier transform infrared spectrometer, compensating the reference light path by adopting a blank cell which is not filled with the standard sample, and respectively measuring the absorbance values of the standard sample.
As a preferred technical scheme of the invention, the Fourier transform infrared spectrometer is 600-800 cm-1The scanning is carried out at a speed of/min, which may be, for example, 600cm-1/min、630cm-1/min、650cm-1/min、680cm-1/min、700cm-1/min、720cm-1/min、750cm-1/min、770cm-1/min、780cm-1Mi or 800cm-1Min, but not limited to the values listed, other values not listed within the range of values are equally applicable.
Preferably, the spectral scanning range of the Fourier transform infrared spectrometer is 2500cm-1～4000cm-1。
Preferably, the absorbance value is an absorbance value corresponding to a characteristic absorption peak of the standard sample.
Preferably, the characteristic absorption peak is 2780cm-1And/or 3370cm-1Characteristic absorption peak of (c).
As a preferred embodiment of the present invention, when scanning formulated LiA1Cl4/SOCl2When the standard sample of the electrolyte is used, the spectral scanning range of the Fourier transform infrared spectrometer is 2500cm-1～4000cm-1。
Preferably, the formulated LiA1Cl4/SOCl2The absorbance values of the standard electrolyte sample are respectively 2780cm-1And 3370cm-1Two absorbance values corresponding to characteristic absorption peaks.
When measuring formulated LiA1Cl4/SOCl2When the water absorption capacity of the electrolyte is high, the characteristic absorption peak (2780 cm) of HCl is obtained by scanning infrared spectrum-1Has a characteristic absorption peak), and absorbance corresponding to AlCl3OH-Characteristic absorption peak of (3370 cm)-1Having a characteristic absorption peak) are substituted into the LiA1Cl4/SOCl2And obtaining two water absorption values in two fitting curve equations obtained by fitting the standard electrolyte sample, and then adding the two water absorption values to obtain the water absorption of the electrolyte sample.
Preferably, when scanning pure SOCl2When the standard sample is used, the spectral scanning range of the Fourier transform infrared spectrometer is 2500cm-1～3000cm-1。
Preferably, the pure SOCl2The absorbance value of the standard sample is 2780cm-1The corresponding absorbance value at the characteristic absorption peak.
When the measurement contained only SOCl2When the water absorption capacity of the electrolyte sample is higher than that of the electrolyte sample, the characteristic absorption peak (2780 cm) of HCl is directly obtained by infrared spectrum measurement-1Having a characteristic absorption peak) into a pure SOCl2And obtaining the corresponding water absorption capacity in a fitting curve equation obtained by fitting the standard sample.
Preferably, the fitted curve equation of the standard sample takes the absorbance value as an abscissa, and the volume of the added deionized water accounts for 100mL of pure SOCl2Or formulated LiA1Cl4/SOCl2The mass concentration of the electrolyte is plotted on the ordinate.
Preferably, any one of exponential fitting, linear fitting, logarithmic fitting or polynomial fitting is adopted to fit a fitting curve equation of water absorption capacity and absorbance.
As a preferred embodiment of the present invention, the measurement of the absorbance of the sample to be measured is the same as the measurement condition of the absorbance of the standard sample.
Preferably, the water absorption of the lithium sub-battery electrolyte or the sample to be measured is measured after rectification.
Preferably, the water absorption of the lithium sub-battery electrolyte or the sample to be tested is measured within 4 to 6 hours after the rectification is completed, for example, the water absorption can be 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours, but the measurement is not limited to the recited values, and other values not recited in the numerical range are also applicable.
The method for measuring the water absorption capacity of the lithium sub-battery electrolyte based on the infrared spectrum can be used for directly measuring the water absorption capacity of the lithium sub-battery electrolyte or a sample to be measured, or can be used for measuring the purity of the rectified lithium sub-battery electrolyte or the sample to be measured. Illustratively, in the present invention, pure SOCl can be obtained by multiple distillation purification of lithium subcell electrolyte2And further preparing the required standard sample.
Preferably, the measurement of the absorbance of the sample to be measured is the same as the measurement condition of the standard sample.
As a preferred technical scheme of the invention, the method specifically comprises the following steps:
six 100mL portions of pure SOCl were placed in glove boxes containing dry air2Or formulated LiA1Cl4/SOCl2Electrolyte, which is respectively injected into six iodine measuring bottles dried at high temperature and marked as A, B, C, D, E, F;
(II) respectively injecting 0 muL, 5 muL, 10 muL, 20 muL, 30 muL and 40 muL of deionized water into the iodine measuring flask in the step (I) by using a dried sample injection needle, covering a bottle plug on the iodine measuring flask, fully shaking and uniformly mixing, and standing in a glove box for 1.5-4 h to completely react to obtain a standard sample;
(III) filling the sample cells of the quartz window with six standard samples by using an injector, sealing and placing on a Fourier transform infrared spectrometer, compensating a reference light path by using the same blank cell without the sample, and filling the reference light path with 800cm-1Scanning at a speed of 2500 cm/min-1～4000cm-12780cm of the six standard samples are measured-1And/or 3370cm-1The absorbance value corresponding to the characteristic absorption peak of (1) is taken as the abscissa, and the volume of the added deionized water accounts for 100mL of pure SOCl2Or formulated LiA1Cl4/SOCl2Drawing the mass concentration of the electrolyte as a vertical coordinate to obtain a fitting curve equation;
(IV) at relative humidity<In a 2% glove box, a sample to be tested is taken, a sample cell of a quartz window is filled with the sample cell, the sample cell is placed on a Fourier transform infrared spectrometer for testing, and the length of the sample cell is measured to be 2780cm-1And/or 3370cm-1Substituting the corresponding absorbance value of the characteristic absorption peak into the fitting curve equation in the step (III) to obtain the corresponding water absorption capacity.
Compared with the prior art, the invention has the beneficial effects that:
the method for measuring the water absorption capacity of the lithium-ion battery electrolyte based on the infrared spectroscopy has the advantages that the detection result is accurate and has small error, the water absorption capacity of the electrolyte can be quantitatively measured, and the problems of low efficiency and low precision of electrolyte water measurement are effectively solved.
Drawings
FIG. 1 shows AlCl provided by the present invention3OH-And a schematic representation of characteristic absorption peaks in the HCl infrared spectrum;
FIG. 2 shows SOCl provided in example 1 of the present invention2A relation graph of the absorbance of the standard sample and the content of the added water;
FIG. 3 shows a formulated LiA1Cl provided in example 2 of the present invention4/SOCl2A relation graph of HCl characteristic absorption peak absorbance and added water content in an electrolyte standard sample;
FIG. 4 is a schematic representation of formulated LiAlCl as provided in example 2 of the present invention4/SOCl2AlCl in standard electrolyte sample3OH-The characteristic absorption peak absorbance and the added water content are plotted.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
The embodiment provides a SOCl based on infrared spectroscopy2The method for absorbing water comprises the following steps:
six 100mL portions of pure SOCl were placed in glove boxes containing dry air2Respectively injecting into six iodine vials dried at high temperature, and marking A, B, C, D, E, F;
(II) respectively injecting deionized water with the amount shown in the table into the iodine measuring flask in the step (I) by adopting a dried sample injection needle, covering an iodine measuring flask with an iodine measuring flask plug, fully shaking, uniformly mixing, standing in a glove box for 2 hours to completely react to obtain a standard sample, wherein pure SOCl is used as a standard sample2The original water content was set to unknown a:
TABLE 1
(III) six standard samples were separately injected by syringeThe sample cell filled with quartz window is sealed and placed on a Fourier transform infrared spectrometer, and a reference light path is compensated by the same blank cell without the injected sample, and the cell length is 800cm-1Scanning at a speed of 2500 cm/min-1～3000cm-12780cm of the six standard samples are measured-1The results of the absorbance values corresponding to the characteristic absorption peaks are shown in Table 2, and then the absorbance values are plotted on the abscissa, and the volume of the deionized water added in Table 1 is 100mL of pure SOCl2The mass concentration of (a) is plotted for the ordinate, and a curve equation is fitted, as shown in fig. 2, the obtained fitted curve equation is:
y＝295.22x-211.24
TABLE 2
| Numbering | A | B | C | D | E | F |
| Absorbance value | 0.75 | 0.87 | 1.01 | 1.4 | 1.79 | 2.03 |
(IV) at relative humidity<In a 2% glove box, taking the SOCl to be measured2Filling a sample cell filled with a quartz window, testing on a Fourier transform infrared spectrometer, and measuring to 2780cm-1And substituting the corresponding absorbance value x at the absorption peak into a fitting curve equation of y-295.22 x to obtain the corresponding water absorption capacity.
Example 2
The embodiment provides LiA1Cl based on infrared spectrometry4/SOCl2The method for absorbing water of the electrolyte comprises the following specific steps:
six 100mL portions of each formulated LiA1Cl were placed in glove boxes containing dry air4/SOCl2Electrolyte is respectively injected into six iodine measuring bottles which are dried at high temperature and marked with A, B, C, D, E, F;
(II) respectively injecting deionized water with the amount shown in the following table 3 into the iodine measuring flask in the step (I) by adopting a dried sample injection needle, covering an iodine measuring flask with an iodine measuring flask plug, fully shaking, uniformly mixing, standing in a glove box for 2 hours to completely react to obtain a standard sample, wherein LiA1Cl4/SOCl2The original water content is set as unknown b:
TABLE 3
(III) filling the sample cells of the quartz window with six standard samples by using an injector, sealing and placing on a Fourier transform infrared spectrometer, compensating a reference light path by using the same blank cell without the sample, and filling the reference light path with 800cm-1Speed scanning at/min from 4000cm-1To 2500cm-1Scanning to measure the six standard samples to 3370cm-1Absorbance value A corresponding to characteristic absorption peak1And 2780cm from-1Absorbance value A corresponding to characteristic absorption peak2The results are shown in table 4:
then measured as absorbance value A1In abscissa, LiA1Cl formulated with a volume of deionized water added in Table 3 of 100mL4/SOCl2Drawing the mass concentration of the electrolyte as a vertical coordinate to obtain a fitting curve equation y1As shown in fig. 3, the obtained fitting curve equation is:
y1＝378.72 x1-82.532
then using absorbance value A2As an abscissa, LiA1Cl formulated with a volume of deionized water added in Table 3 of 100mL4/SOCl2Drawing the mass concentration of the electrolyte as a vertical coordinate to obtain a fitting curve equation y2As shown in fig. 4, the obtained fitting curve equation is:
y2＝645.45 x2-316.62
TABLE 4
| Numbering | A | B | C | D | E | F |
| Absorbance value A1 | 0.242 | 0.335 | 0.48 | 0.736 | 0.997 | 1.29 |
| Absorbance value A2 | 0.48 | 0.57 | 0.65 | 0.81 | 0.96 | 1.1 |
(IV) at relative humidity<Taking LiA1Cl to be tested in a 2% glove box4/SOCl2Filling the sample cell with the electrolyte sample, testing with Fourier transform infrared spectrometer, and measuring to obtain 3370cm-1Absorbance value x corresponding to characteristic absorption peak1And 2780cm-1Absorbance value x corresponding to absorption peak2Substituted into y-378.72 x1+645.45x2Fitting a curve equation to obtain LiA1Cl4/SOCl2Water uptake of the electrolyte sample.
The fit curve equation obtained by fitting in example 1 has an intercept of 211.24, indicating pure SOCl2The original water content a was 211.24ppm, and the intercepts of the two fitted curve equations fitted in example 2 were 82.532 and 316.62, respectively, indicating LiA1Cl4/SOCl2The original water content b is 82.532+316.62 399.152ppm
The method for measuring the water absorption capacity of the lithium-ion battery electrolyte based on the infrared spectroscopy has the advantages that the detection result is accurate and has small error, the water absorption capacity of the electrolyte can be quantitatively measured, and the problems of low efficiency and low precision of electrolyte water measurement are effectively solved.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A method for measuring the water absorption capacity of an electrolyte of a lithium subcell based on infrared spectroscopy is characterized by comprising the following steps:
preparing at least three groups of standard samples of lithium subcell electrolyte, respectively measuring absorbance values of different standard samples through infrared spectroscopy, and fitting to obtain a fitting curve equation of absorbance and water absorption capacity; and measuring the absorbance of the sample to be measured by an infrared spectroscopy, and substituting the absorbance into a fitting curve equation to obtain the water absorption capacity of the sample to be measured.
2. The method according to claim 1, wherein the standard sample preparation process comprises:
taking at least three equal parts of lithium sub-battery electrolyte, and respectively adding deionized water with different volumes into each part of lithium sub-battery electrolyte to obtain a standard sample;
preferably, the standard sample is numbered;
preferably, the volume of the added deionized water increases in a gradient;
preferably, the difference value of the gradients is 5-15 mu L;
preferably, the electrolyte of the lithium sub-battery is taken as six parts with equal quantity;
preferably, 0. mu.L, 5. mu.L, 10. mu.L, 20. mu.L, 30. mu.L and 40. mu.L of deionized water are added to the six equal amounts of lithium subcell electrolyte, respectively.
3. The method of claim 1 or 2, wherein the lithium subcell electrolyte is pure SOCl2Or formulated LiA1Cl4/SOCl2An electrolyte;
preferably, the water absorption is pure SOCl2Or formulated LiA1Cl4/SOCl2The sum of the original water content in the electrolyte and the added deionized water;
preferably, the electrolyte of the lithium sub-battery is taken into a containing container;
preferably, the holding container is an iodine measuring bottle;
preferably, the sampling of the lithium sub-battery electrolyte is carried out in a glove box filled with dry air;
preferably, the relative humidity inside the glove box is < 2%.
4. The method of claim 3, wherein deionized water is added to the iodine vials separately using a sample injection needle;
preferably, the sampling needle is a dry micro sampling needle;
preferably, the needle head of the sample injection needle extends into the iodine measuring flask below the liquid level to add the deionized water.
5. The method of claim 4, wherein the iodine flask is sufficiently shaken after the deionized water is added to uniformly mix the electrolyte of the lithium subcell with the deionized water;
preferably, standing the uniformly mixed iodine bottles for full reaction;
preferably, the reaction time is 1.5-4 h.
6. The method according to any one of claims 1 to 5, characterized in that said infrared spectrometric measurement method comprises in particular:
and filling the sample cell of the quartz window with the standard sample, sealing and placing on a Fourier transform infrared spectrometer, compensating the reference light path by adopting a blank cell which is not filled with the standard sample, and respectively measuring the absorbance values of the standard sample.
7. The method of claim 6, wherein the Fourier transform infrared spectrometer is at 600-800 cm-1Scanning at a speed of/min;
preferably, the spectral scanning range of the Fourier transform infrared spectrometer is 2500cm-1～4000cm-1；
Preferably, the absorbance value is the absorbance value corresponding to the characteristic absorption peak of the standard sample;
preferably, the characteristic absorption peak is 2780cm-1And/or 3370cm-1Characteristic absorption peak of (c).
8. The method according to claim 6 or 7, characterized in that when scanning formulated LiA1Cl4/SOCl2When the standard sample of the electrolyte is used, the spectral scanning range of the Fourier transform infrared spectrometer is 2500cm-1～4000cm-1；
Preferably, the formulated LiA1Cl4/SOCl2The absorbance values of the standard electrolyte sample are respectively 2780cm-1And 3370cm-1Two absorbance values corresponding to the characteristic absorption peak;
preferably, when scanning pure SOCl2When the standard sample is used, the spectral scanning range of the Fourier transform infrared spectrometer is 2500cm-1～3000cm-1；
Preferably, the pure SOCl2The absorbance value of the standard sample is 2780cm-1The corresponding absorbance value at the characteristic absorption peak;
preferably, the fitted curve equation of the standard sample takes the absorbance value as an abscissa, and the volume of the added deionized water accounts for 100mL of pure SOCl2Or formulated LiA1Cl4/SOCl2Drawing the mass concentration of the electrolyte as a vertical coordinate;
preferably, any one of exponential fitting, linear fitting, logarithmic fitting or polynomial fitting is adopted to fit a fitting curve equation of water absorption capacity and absorbance.
9. The method according to any one of claims 1 to 8, wherein the measurement of the absorbance of the test sample is the same as the measurement condition of the absorbance of the standard sample;
preferably, the water absorption of the lithium sub-battery electrolyte or the sample to be measured is measured after rectification;
preferably, the water absorption of the lithium sub-battery electrolyte or the sample to be detected is measured within 4-6 hours after rectification is completed.
10. The method according to any one of claims 1 to 9, characterized in that it comprises in particular the steps of:
six 100mL portions of pure SOCl were placed in glove boxes containing dry air2Or formulated LiA1Cl4/SOCl2Electrolyte, which is respectively injected into six iodine measuring bottles dried at high temperature and marked as A, B, C, D, E, F;
(II) respectively injecting 0 muL, 5 muL, 10 muL, 20 muL, 30 muL and 40 muL of deionized water into the iodine measuring flask in the step (I) by using a dried sample injection needle, covering a bottle plug on the iodine measuring flask, fully shaking and uniformly mixing, and standing in a glove box for 1.5-4 h to completely react to obtain a standard sample;
(III) respectively filling the sample cells of the quartz window with six standard samples by using an injector, sealing and then placing on a Fourier transform infrared spectrometer, compensating a reference light path by using the same blank cell without the sample, and filling the reference light path with 600-800 cm-1Speed scan/min, scan range 2500cm-1～4000cm-12780cm of the six standard samples are measured-1And/or 3370cm-1The absorbance value corresponding to the characteristic absorption peak of (1) is taken as the abscissa, and the volume of the added deionized water accounts for 100mL of pure SOCl2Or formulated LiA1Cl4/SOCl2Drawing the mass concentration of the electrolyte as a vertical coordinate to obtain a fitting curve equation;
(IV) at relative humidity<In a 2% glove box, a sample to be tested is taken, a sample cell of a quartz window is filled with the sample cell, the sample cell is placed on a Fourier transform infrared spectrometer for testing, and the length of the sample cell is measured to be 2780cm-1And/or 3370cm-1Substituting the corresponding absorbance value of the characteristic absorption peak into the fitting curve equation in the step (III) to obtain the corresponding water absorption capacity.
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