CN115015225A - Method for measuring contents of phosphorus, iron and lithium in lithium iron phosphate for lithium ion battery - Google Patents
Method for measuring contents of phosphorus, iron and lithium in lithium iron phosphate for lithium ion battery Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 42
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 37
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 34
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 34
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 34
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 34
- 229910052698 phosphorus Inorganic materials 0.000 title claims abstract description 34
- 239000011574 phosphorus Substances 0.000 title claims abstract description 34
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 28
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 28
- 238000012360 testing method Methods 0.000 claims abstract description 41
- 239000007788 liquid Substances 0.000 claims abstract description 34
- 238000003908 quality control method Methods 0.000 claims abstract description 17
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 14
- 238000005303 weighing Methods 0.000 claims abstract description 13
- 238000004364 calculation method Methods 0.000 claims abstract description 8
- 238000010606 normalization Methods 0.000 claims abstract description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 40
- 239000000523 sample Substances 0.000 claims description 33
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 28
- 230000029087 digestion Effects 0.000 claims description 27
- 239000000243 solution Substances 0.000 claims description 27
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 20
- 229910017604 nitric acid Inorganic materials 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 13
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 10
- 239000012498 ultrapure water Substances 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 8
- 239000012086 standard solution Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000002253 acid Substances 0.000 claims description 6
- 238000012937 correction Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- 229910000510 noble metal Inorganic materials 0.000 claims description 5
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- 238000000120 microwave digestion Methods 0.000 claims description 4
- 238000012986 modification Methods 0.000 claims description 3
- 230000004048 modification Effects 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 239000013062 quality control Sample Substances 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- YQCIWBXEVYWRCW-UHFFFAOYSA-N methane;sulfane Chemical compound C.S YQCIWBXEVYWRCW-UHFFFAOYSA-N 0.000 claims description 2
- 239000007774 positive electrode material Substances 0.000 claims description 2
- 238000004876 x-ray fluorescence Methods 0.000 claims description 2
- 238000003556 assay Methods 0.000 claims 2
- 238000005259 measurement Methods 0.000 claims 1
- 238000004451 qualitative analysis Methods 0.000 claims 1
- 238000001228 spectrum Methods 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 8
- 239000011159 matrix material Substances 0.000 abstract description 8
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 4
- 229910052727 yttrium Inorganic materials 0.000 description 11
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 11
- 238000009616 inductively coupled plasma Methods 0.000 description 10
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 8
- 238000010998 test method Methods 0.000 description 7
- 239000010405 anode material Substances 0.000 description 5
- 238000004993 emission spectroscopy Methods 0.000 description 4
- 229910052746 lanthanum Inorganic materials 0.000 description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910052706 scandium Inorganic materials 0.000 description 4
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 4
- 238000010561 standard procedure Methods 0.000 description 3
- 238000004448 titration Methods 0.000 description 3
- 238000000184 acid digestion Methods 0.000 description 2
- 238000012550 audit Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000005048 flame photometry Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 238000003918 potentiometric titration Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229910010710 LiFePO Inorganic materials 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- YVBOZGOAVJZITM-UHFFFAOYSA-P ammonium phosphomolybdate Chemical compound [NH4+].[NH4+].[NH4+].[NH4+].[O-]P([O-])=O.[O-][Mo]([O-])(=O)=O YVBOZGOAVJZITM-UHFFFAOYSA-P 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000000553 indicators and reagents Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000012085 test solution Substances 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
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/73—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using plasma burners or torches
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/38—Diluting, dispersing or mixing samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/44—Sample treatment involving radiation, e.g. heat
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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
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- General Health & Medical Sciences (AREA)
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- Immunology (AREA)
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Abstract
The invention relates to a method for measuring the content of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery, which comprises the following steps: drying a sample to be detected, weighing the sample, digesting to obtain a liquid to be detected, and preparing a blank liquid; preparing an ICP-OES test standard working curve; calculating the contents of phosphorus, iron and lithium according to the weight of the sample, and preparing a quality control solution; testing the blank liquid, the liquid to be tested and the quality control liquid, and correcting the test result according to the quality control liquid; and carrying out normalized calculation to obtain the contents of phosphorus, iron and lithium in the lithium iron phosphate for the lithium ion battery. According to the invention, three main elements in the lithium iron phosphate are tested simultaneously through ICP-OES, so that the detection efficiency is improved, and the types of used chemical reagents are effectively reduced; through matrix matching and internal standard addition, the influence of matrix effect and equipment fluctuation on ICP-OES test is eliminated; the condition of large deviation of the total content is avoided through normalization, and the accuracy of the test is improved.
Description
Technical Field
The invention belongs to the field of lithium ion battery detection, and relates to a method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery.
Background
The lithium iron phosphate is used as the anode material of the lithium ion battery, and has the advantages of high energy density, good safety performance, long cycle life and the like. At present, the production technology of the lithium iron phosphate material is mature, and the national standards (GB/T30835 and GB/T33822) and the industry standard (YS/T1027) are correspondingly provided, wherein the standards all make detailed requirements on various physical and chemical properties of the lithium iron phosphate.
The standard iron content test method comprises a titration method (GB/T30835-2014, YS/T1028.1-2015) and a potentiometric titration method (GB/T33822-2017). The method for testing the phosphorus content comprises an ammonium phosphomolybdate volumetric method (GB/T30835-2014) and a quinomolybdenum citranone weight method (GB/T33822-2017 and YS/T1028.3-2015). The testing methods of the lithium content include inductively coupled plasma emission spectrometry (GB/T30835 2014, GB/T33822 2017) and flame photometry (YS/T1028.2-2015). The prior art methods also include titration, gravimetric, inductively coupled plasma emission spectroscopy, and the like.
However, flame photometry involves the use of flammable and explosive gases, with an increased risk factor; titration methods and gravimetric methods, including potentiometric titration methods, require preparation of a variety of reagents and indicators, most involve preparation and calibration of specific reagents, the testing steps are complicated, and the requirements on the quality of testing personnel are high; the inductively coupled plasma emission spectrometry mostly involves dilution of test solution and matching of non-emphasized matrixes, the content of each element belongs to a constant range, the direct test data sometimes fluctuate greatly, and the test result is according to the molecular formula of lithium iron phosphate (LiFePO) 4 ) After conversion, a deviation of the total content may occur (for example: over 100% or under 100%).
In the technical scheme, the phosphorus, the iron and the lithium are separately tested according to a standard method, so that the efficiency is lower in large-batch detection of lithium iron phosphate production and use methods.
Therefore, the method for simultaneously detecting phosphorus, iron and lithium in the lithium iron phosphate cathode material is an urgent technical problem to be solved in the field of lithium ion battery detection.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for measuring the content of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery, which can realize the simultaneous test of three main elements in the lithium iron phosphate for the lithium ion battery by inductively coupled plasma emission spectrometry (ICP-OES), thereby improving the detection efficiency, effectively reducing the variety of used chemical reagents and simplifying the test operation steps.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for measuring the contents of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery, which comprises the following steps:
(1) drying a sample to be detected, weighing the sample, digesting to obtain a liquid to be detected, and preparing a blank liquid;
(2) preparing an ICP-OES test standard working curve;
(3) calculating the contents of phosphorus, iron and lithium according to the mass of the sample weighed in the step (1) to prepare a quality control solution;
(4) testing the blank liquid, the liquid to be tested and the quality control liquid, and correcting the test result of the liquid to be tested according to the test result of the quality control liquid; (ii) a
(5) And carrying out normalized calculation to obtain the contents of phosphorus, iron and lithium in the lithium ion battery.
According to the invention, three main elements in lithium iron phosphate for the lithium ion battery can be simultaneously tested through ICP-OES, so that the detection efficiency is improved, the types of used chemical reagents are effectively reduced, and the test operation steps are simplified; the result fluctuation caused by personnel operation errors can be eliminated through normalization of a special data processing mode, the condition of large total content deviation is avoided, the test accuracy is improved, and the method is suitable for shipment inspection in the lithium iron phosphate production process and quality audit before use.
The difference between the liquid to be detected and the blank liquid in the invention is as follows: the blank liquid has no sample to be detected, and the solvent, the concentration of other elements and the digestion conditions of the blank liquid are the same as those of the liquid to be detected.
Preferably, the sample to be detected in step (1) includes a lithium iron phosphate positive electrode material.
Preferably, the temperature of the drying is 100 ℃ to 120 ℃, for example, 100 ℃, 105 ℃, 110 ℃, 115 ℃ or 120 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the drying time in step (1) is 1h to 3h, such as 1h, 1.5h, 2h, 2.5h or 3h, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the digestion manner in the step (1) comprises microwave digestion and/or acid solution digestion.
Preferably, the method of solution digestion comprises: and mixing the digestion solution and the sample to be measured after drying and weighing, heating until complete digestion, and filtering.
Preferably, the digestion solution includes any one of hydrochloric acid, nitric acid or perchloric acid or a combination of at least two thereof, and typical but non-limiting combinations include a combination of hydrochloric acid and nitric acid, a combination of nitric acid and perchloric acid, a combination of hydrochloric acid and perchloric acid, or a combination of hydrochloric acid, nitric acid and perchloric acid, preferably a combination of hydrochloric acid, hydrochloric acid and nitric acid, hydrochloric acid and perchloric acid, or a combination of hydrochloric acid, nitric acid and perchloric acid, and further preferably aqua regia (volume ratio, hydrochloric acid: nitric acid ═ 3: 1).
Preferably, the heating temperature is 150 ℃ to 180 ℃, for example 150 ℃, 160 ℃, 170 ℃, 175 ℃ or 180 ℃, but not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the heating time is 20min to 40min, for example 20min, 25min, 30min, 35min or 40min, but is not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the digesting in the step (1) further comprises mixing with an internal standard element and carrying out constant volume.
Preferably, the solvent of constant volume comprises ultrapure water.
Preferably, the internal standard element comprises a rare earth element and/or a noble metal.
The rare earth element comprises any one or a combination of at least two of yttrium, scandium, or lanthanum, with typical but non-limiting combinations including yttrium and scandium, scandium and lanthanum, yttrium and lanthanum, or yttrium, scandium, and lanthanum, preferably yttrium.
The noble metal comprises indium and/or rhodium.
Preferably, the formulating of step (2) comprises formulating gradient points of a standard working curve.
Preferably, the gradient points are prepared according to the mass of the weighed sample in the step (1) and converted according to the volume of the constant volume in the step (1).
Preferably, the gradient point is formulated as described in step (1) at 70 wt% to 130 wt% of the weighed mass, for example 70 wt%, 80 wt%, 90 wt%, 100 wt%, 110 wt%, 120 wt% or 130 wt%, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
The formulation at 70 wt% to 130 wt% of the weighed sample mass is due to taking into account weighing fluctuations.
Preferably, the quality control sample in step (3) comprises lithium, iron and phosphorus.
Preferably, the quality control solution in the step (3) is prepared according to the sample weighing mass, the acid solution adding amount and the constant volume of the sample according to the LiFePO 4 And converting the mass concentrations of lithium, iron and phosphorus, and preparing by using a standard solution.
Preferably, the digestion manner in the step (2) comprises microwave digestion and/or solution digestion.
Preferably, the method of solution digestion comprises: and mixing the digestion solution and the sample to be measured after drying and weighing, heating until complete digestion, and filtering.
Preferably, the digestion solution includes any one of hydrochloric acid, nitric acid or perchloric acid or a combination of at least two thereof, and typical but non-limiting combinations include a combination of hydrochloric acid and nitric acid, a combination of nitric acid and perchloric acid, a combination of hydrochloric acid and perchloric acid, or a combination of hydrochloric acid, nitric acid and perchloric acid, preferably a combination of hydrochloric acid, hydrochloric acid and nitric acid, hydrochloric acid and perchloric acid, or a combination of hydrochloric acid, nitric acid and perchloric acid, and further preferably aqua regia (volume ratio, hydrochloric acid: nitric acid ═ 3: 1).
Preferably, the heating temperature is 150 ℃ to 180 ℃, for example 150 ℃, 160 ℃, 170 ℃, 175 ℃ or 180 ℃, but not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the heating time is 20min to 40min, for example 20min, 25min, 30min, 35min or 40min, but is not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the digesting in the step (2) further comprises mixing with an internal standard element and carrying out volume metering.
Preferably, the solvent of constant volume comprises ultrapure water.
Preferably, the internal standard element comprises a rare earth element and/or a noble metal.
According to the invention, the sample is converted into the solution by adopting an acid digestion mode, and the influence of matrix effect and equipment fluctuation on ICP-OES test is eliminated by matrix matching and internal standard addition.
Preferably, before the test in step (4), the linear correlation coefficient is above 0.999, such as 0.999, 0.9999, 0.99999, 0.99999999 or 0.9999999, but not limited to the values listed, and other values not listed in the numerical range are also applicable.
Preferably, the formula of the modification in step (4) is:
preferably, the formula of the normalization calculation in step (5) is:
wherein M (Li) and M (Li) 2 O)、M(Fe)And M (FeO), M (P) and M (P) 2 O 5 ) Respectively represent the molar masses of the element and the corresponding oxide, w (Li) and w (Li) Correction W (Fe) and w (Fe) Correction W (P) and w (P) Correction Respectively representing the calculated value and the corrected value of the element mass percentage content, and S is a conversion coefficient.
Preferably, the calculation formula of the conversion coefficient S is S ═ 100% -w (c) -w (total amount of impurities), where w (c) represents the mass percentage content of carbon in the sample to be measured, and w (total amount of impurities) represents the total mass percentage content of impurity elements in the sample to be measured.
Preferably, the method of determination of w (c) comprises high frequency carbon sulfur analysis determination.
Preferably, the method for measuring w (total amount of impurities) comprises the steps of performing X-ray fluorescence spectrum analysis, and then quantitatively measuring by ICP-OES.
Compared with the prior art, the invention has at least the following beneficial effects:
according to the invention, three main elements in the lithium ion battery are simultaneously tested through ICP-OES, so that the detection efficiency is improved, the types of used chemical reagents are effectively reduced, and the test operation steps are simplified; the sample is converted into a solution by adopting an acid digestion mode, and the influence of matrix effect and equipment fluctuation on ICP-OES test is eliminated through matrix matching and internal standard addition; the result fluctuation caused by personnel operation errors can be eliminated through normalization of a special data processing mode, the condition of large total content deviation is avoided, the test accuracy is improved, and the method is suitable for shipment inspection in the lithium iron phosphate production process and quality audit before use.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a method for measuring the contents of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery, which comprises the following steps:
(1) placing the lithium iron phosphate anode material in a constant-temperature drying box for drying at the temperature of 110 ℃ for 2h, weighing 0.1g (accurate to 0.0001g) of the lithium iron phosphate anode material as a sample to be detected, mixing the sample with 20mL of aqua regia (40%), heating and digesting for 30min at 160 ℃, filtering and transferring to a 250mL volumetric flask (filter residue is washed for more than or equal to 3 times), adding 0.75mL of standard solution of an internal standard element yttrium (2000 microgrammes/mL) into the volumetric flask, and shaking up after constant volume of ultrapure water to obtain a liquid to be detected;
taking another 250mL volumetric flask, adding 0.75mL standard solution of internal standard element yttrium (2000 mug/mL), metering the volume with ultrapure water, and shaking up to obtain blank liquid;
(2) preparing gradient points of a standard working curve according to the following table, wherein the gradient points are in mg/L:
| element(s) | STD 0 | STD 1 | STD 2 | STD 3 | STD 4 | STD 5 |
| Li | 0 | 12 | 15 | 18 | 21 | 24 |
| Fe | 0 | 98 | 120 | 142 | 164 | 186 |
| P | 0 | 55 | 67 | 79 | 91 | 103 |
| Y | 6.0 | 6.0 | 6.0 | 6.0 | 6.0 | 6.0 |
Wherein the volume is 100mL, and 8mL of aqua regia (40%) is added; STD is gradient points, each gradient point is obtained by conversion according to the sample weighing mass and the volume fixing volume in the step (1), each gradient point is prepared according to 70-130 wt% of the sample weighing mass, and the internal standard elements and the concentration need to be consistent with those in the step (1).
(3) Respectively transferring phosphorus, iron and lithium standard solutions as quality control samples and 8mL of aqua regia (40%) into a 100mL volumetric flask, adding an internal standard element yttrium into the volumetric flask, carrying out constant volume on ultrapure water, shaking up to prepare the following concentrations, and obtaining the quality control solutions as shown in the following table:
(4) and (3) sequentially testing the standard working curve, the blank liquid, the liquid to be tested and the quality control liquid, and directly testing by adopting a radial observation mode, wherein the linear correlation coefficient is 0.999.
The modified formula is:
the formula of the normalization calculation is:
the results obtained by the measurement method, the standard method GB/T33822-2017 and the ICP direct test method in this embodiment are shown in the following table, wherein the ICP direct test method is different from the method provided by this embodiment only in that the test results are not normalized:
as can be seen from the above table, the results obtained by using ICP in this example are large overall, probably because the amount of the internal standard is small, the normalized results provided by this example are far lower than the tolerance specified in the test method GB/T33822-2017, the RSD of lithium is less than 0.15%, and the RSD of iron and phosphorus is less than 0.40%.
Example 2
The embodiment provides a method for measuring the contents of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery, which comprises the following steps:
(1) placing the lithium iron phosphate anode material in a constant-temperature drying box for drying at the drying temperature of 110 ℃ for 2h, weighing 0.25g of the lithium iron phosphate anode material as a sample to be detected, digesting the sample with 20mL of aqua regia (1:1), transferring the sample to a 250mL volumetric flask for constant volume, filtering the solution, taking 5mL to 100mL of filtrate in the volumetric flask, adding 5mL of yttrium standard solution (100mg/L) and 5mL of nitric acid, and adding ultrapure water for constant volume to obtain a solution to be detected;
5mL of an yttrium standard solution (100mg/L) and 5mL of nitric acid were added to a 100mL volumetric flask, and a blank liquid was obtained by diluting with ultrapure water to a constant volume.
(2) Preparing gradient points of a standard working curve according to the following table, wherein the gradient points are in mg/L:
| element(s) | STD 0 | STD 1 | STD 2 | STD 3 |
| Li | 0 | 1.5 | 2.2 | 2.9 |
| Fe | 0 | 12.5 | 17.5 | 23 |
| P | 0 | 6.8 | 9.8 | 12.8 |
| Y | 5.0 | 5.0 | 5.0 | 5.0 |
Wherein the volume of constant volume is 100mL, and 0.5mL of aqua regia and 5mL of nitric acid are added; STD is gradient points, each gradient point is obtained by conversion according to the sample weighing mass and the volume fixing volume in the step (1), each gradient point is prepared according to 70-130 wt% of the sample weighing mass, and the internal standard elements and the concentration need to be consistent with those in the step (1).
(3) Respectively transferring phosphorus, iron and lithium standard solutions serving as quality control samples, 0.5mL of aqua regia and 5mL of nitric acid into a 100mL volumetric flask, adding an internal standard element yttrium into the volumetric flask, shaking up after constant volume of ultrapure water, and preparing into the following concentration, wherein the obtained quality control solution is shown in the following table:
(4) and (3) sequentially testing the standard working curve, the blank liquid, the liquid to be tested and the quality control liquid, and directly testing by adopting a radial observation mode, wherein the linear correlation coefficient is 0.999.
The modified formula is:
the formula of the normalization calculation is:
the results obtained by the measurement method, the standard method GB/T33822-2017 and the ICP direct test method in this embodiment are shown in the following table, wherein the ICP direct test method is different from the method provided by this embodiment only in that the test results are not normalized:
as can be seen from the above table, the ICP-OES axial observation test is used in this embodiment. The ICP direct test result is smaller overall, probably because the dilution sampling volume is smaller, the normalized result tolerance provided by the embodiment is far lower than the tolerance specified by the GB/T33822-2017 test method, the RSD of lithium is less than 0.15%, and the RSD of iron and phosphorus is less than 0.40%.
In conclusion, the ICP-OES is used for simultaneously testing three main elements in the lithium ion battery, so that the detection efficiency is improved, the types of used chemical reagents are effectively reduced, and the test operation steps are simplified; through matrix matching and internal standard addition, the influence of matrix effect and equipment fluctuation on ICP-OES test is eliminated; the condition of large deviation of the total content is avoided through normalization, and the accuracy of the test is improved.
The present invention is illustrated by the above examples, but the present invention is not limited to the above detailed process equipment and process flow, which means that the present invention must not be implemented by the above detailed process equipment and process flow. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A method for measuring the contents of phosphorus, iron and lithium in lithium iron phosphate for a lithium ion battery is characterized by comprising the following steps:
(1) drying a sample to be detected, weighing the sample, digesting to obtain a liquid to be detected, and preparing a blank liquid;
(2) preparing an ICP-OES test standard working curve;
(3) calculating the contents of phosphorus, iron and lithium according to the mass of the sample weighed in the step (1) to prepare a quality control solution;
(4) testing the blank liquid, the liquid to be tested and the quality control liquid, and correcting the test result of the liquid to be tested according to the test result of the quality control liquid;
(5) and carrying out normalized calculation to obtain the contents of phosphorus, iron and lithium in the lithium iron phosphate for the lithium ion battery.
2. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for the lithium ion battery according to claim 1, wherein the sample to be tested in the step (1) comprises a lithium iron phosphate positive electrode material;
preferably, the drying temperature in the step (1) is 100-120 ℃;
preferably, the drying time in the step (1) is 1h-3 h.
3. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for the lithium ion battery according to claim 1 or 2, wherein the digestion manner in the step (1) comprises microwave digestion and/or acid solution digestion;
preferably, the method for digestion of the acid solution comprises: mixing the digestion solution and the dried sample to be tested, heating until complete digestion, and filtering;
preferably, the digestion solution comprises any one of hydrochloric acid, nitric acid or perchloric acid or a combination of at least two of the same;
preferably, the temperature of the heating is 150-180 ℃;
preferably, the heating time is 20min to 40 min.
4. The method for measuring the contents of phosphorus, iron and lithium in lithium iron phosphate for the lithium ion battery according to any one of claims 1 to 3, wherein the digestion in the step (1) is further performed by mixing with an internal standard element and performing volume fixing;
preferably, the constant volume solvent comprises ultrapure water;
preferably, the internal standard element comprises a rare earth element and/or a noble metal.
5. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for lithium ion batteries according to any one of claims 1 to 4, wherein the preparing in the step (2) comprises preparing a gradient point of a standard working curve;
preferably, the gradient points are formulated as 70 wt% to 130 wt% of the weighed sample mass of step (1).
6. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for lithium ion batteries according to any one of claims 1 to 5, wherein the quality control sample in the step (3) comprises lithium, iron and phosphorus;
preferably, the quality control solution in the step (3) is prepared by using a standard solution.
7. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for lithium ion batteries according to any one of claims 1 to 6, wherein the preparation process in the step (3) comprises digestion;
preferably, the digestion mode comprises microwave digestion and/or acid solution digestion;
preferably, the method for digestion of the acid solution comprises: mixing the digestion solution and the dried sample to be tested, heating until complete digestion, and filtering;
preferably, the digestion solution comprises any one of hydrochloric acid, nitric acid or perchloric acid, or a combination of at least two of the same;
preferably, the temperature of the heating is 150-180 ℃;
preferably, the heating time is 20min-40 min;
preferably, the digesting comprises mixing with an internal standard element and carrying out constant volume;
preferably, the constant volume solvent comprises ultrapure water;
preferably, the internal standard element comprises a rare earth element and/or a noble metal.
8. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for lithium ion batteries according to any one of claims 1 to 7, wherein before the test in the step (4), the linear correlation coefficient is more than 0.999;
preferably, the formula of the modification in step (4) is:
9. the method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for lithium ion batteries according to any one of claims 1 to 8, wherein the normalization in step (5) is performed by the following formula:
wherein M (Li) and M (Li) 2 O, M (Fe) and M (FeO), M (P) and M (P) 2 O 5 ) Respectively represent the molar masses of the element and of the corresponding oxide, w (Li) andw(Li) correction W (Fe) and w (Fe) Correction W (P) and w (P) Correction Respectively representing the normalized calculation value of the element mass percentage content and the corrected value according to the quality control sample result, and S is a conversion coefficient.
10. The method for determining the content of phosphorus, iron and lithium in lithium iron phosphate for lithium ion batteries according to claim 9, wherein the conversion coefficient S is calculated by using a formula of S ═ 100% -w (c) -w (total amount of impurities), wherein w (c) represents the mass percentage content of carbon in a sample to be measured, and w (total amount of impurities) represents the total mass percentage content of impurity elements in the sample to be measured;
preferably, the assay of w (c) comprises a high frequency carbon sulfur assay;
preferably, the method for measuring w (total amount of impurities) comprises the steps of firstly carrying out qualitative analysis of X-ray fluorescence spectrum and then carrying out quantitative measurement through ICP-OES.
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| CN115508339A (en) * | 2022-09-23 | 2022-12-23 | 湖北虹润高科新材料有限公司 | Method for measuring main component content of lithium iron phosphate slurry and blending device thereof |
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| CN115508339A (en) * | 2022-09-23 | 2022-12-23 | 湖北虹润高科新材料有限公司 | Method for measuring main component content of lithium iron phosphate slurry and blending device thereof |
| CN115508339B (en) * | 2022-09-23 | 2023-11-07 | 湖北虹润高科新材料有限公司 | Method for measuring content of main component of lithium iron phosphate slurry and mixing device thereof |
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