CN111638206A - Method for measuring Fe content in carbon-coated SiO lithium battery negative electrode material - Google Patents
Method for measuring Fe content in carbon-coated SiO lithium battery negative electrode material Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 38
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 29
- 239000007773 negative electrode material Substances 0.000 title claims description 24
- 238000000120 microwave digestion Methods 0.000 claims abstract description 33
- 239000012488 sample solution Substances 0.000 claims abstract description 30
- 239000007788 liquid Substances 0.000 claims abstract description 20
- 239000012498 ultrapure water Substances 0.000 claims abstract description 19
- 239000010406 cathode material Substances 0.000 claims abstract description 15
- 238000009616 inductively coupled plasma Methods 0.000 claims abstract description 15
- 239000012224 working solution Substances 0.000 claims abstract description 13
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 12
- 230000003595 spectral effect Effects 0.000 claims abstract description 10
- 239000012490 blank solution Substances 0.000 claims abstract description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000004458 analytical method Methods 0.000 claims abstract description 6
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 6
- 238000001914 filtration Methods 0.000 claims abstract description 5
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 18
- 239000000523 sample Substances 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 12
- 239000011550 stock solution Substances 0.000 claims description 11
- 239000002253 acid Substances 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 8
- 239000012086 standard solution Substances 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 239000000112 cooling gas Substances 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 4
- 238000005303 weighing Methods 0.000 claims description 4
- 238000009776 industrial production Methods 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 3
- 238000012544 monitoring process Methods 0.000 abstract description 3
- 230000029087 digestion Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 239000000758 substrate Substances 0.000 description 5
- -1 polytetrafluoroethylene Polymers 0.000 description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 238000003556 assay Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000000498 ball milling Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- DPORRQCIAXYPGF-UHFFFAOYSA-N F.Cl.O[N+]([O-])=O Chemical compound F.Cl.O[N+]([O-])=O DPORRQCIAXYPGF-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 238000000713 high-energy ball milling Methods 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000013120 national analysis Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 239000012088 reference solution Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- G01N21/62—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
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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
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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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Abstract
The invention discloses a method for measuring Fe content in a carbon-coated SiO lithium battery cathode material, which comprises the following steps: mixing 0.1-0.3 g of carbon-coated SiO with high-purity water, hydrofluoric acid, nitric acid and hydrochloric acid, and then carrying out microwave digestion, acid-dispelling, volume-fixing and filtering to obtain a sample solution; then preparing a blank liquid and a standard working liquid: selecting an 259.940 wavelength spectral line as an analysis spectral line of the Fe element, measuring the strength of Fe in standard working solution by using an inductively coupled plasma emission spectrometer, then drawing a standard working curve, measuring the strength of Fe in a sample solution and a blank solution by using the inductively coupled plasma emission spectrometer, then obtaining the corresponding mass concentration of the Fe element on the standard working curve by using the strength value of Fe, and then calculating the content of the Fe element. The determination method can quickly, efficiently and accurately detect the content of Fe in the carbon-coated SiO lithium battery cathode material, and can be applied to monitoring the content of impurity Fe in the carbon-coated SiO lithium battery cathode material product in the industrial production process.
Description
Technical Field
The invention relates to the field of analysis and detection, in particular to a method for determining Fe content in a carbon-coated SiO lithium battery cathode material.
Background
Lithium ion batteries have become the most widely used secondary batteries in portable electronic products because of their advantages of high energy density, high open circuit voltage, long cycle life, and no pollution. The SiO material is widely concerned by people due to high specific capacity and excellent cycle performance, and is expected to be used as a substitute product of a graphitized carbon material of a lithium ion battery, however, the wide application of the SiO material is limited due to low intrinsic conductivity of silicon and large volume change of the silicon-based material in the process of lithium ion intercalation/deintercalation. In view of the above problems, in recent years, researchers have conducted extensive research on SiOx-based negative electrode materials, in which the preparation of a carbon-coated SiO composite material by a high-energy ball milling method is one of the methods for improving low capacity battery and long-term cycle stability, but since a small amount of Fe in a ball milling pot and a ball is introduced into the negative electrode material of a carbon-coated SiO lithium battery during ball milling, the conductivity and stability of the battery are affected. At present, no national standard, industrial standard and literature report exists for dissolving a carbon-coated SiO lithium battery cathode material sample by microwave digestion and measuring the Fe content in the carbon-coated SiO lithium battery cathode material by ICP-OES, so that a method for quickly, efficiently and accurately measuring the Fe content in the carbon-coated SiO lithium battery cathode material is urgently needed to be developed to monitor the Fe content, and the method has great application value for guiding industrial production.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides the method for measuring the trace Fe in the carbon-coated SiO lithium battery cathode material, the method can quickly, efficiently, accurately and stably detect the Fe content in the carbon-coated SiO lithium battery cathode material, and can be applied to monitoring the impurity Fe content in the carbon-coated SiO lithium battery cathode material product in the industrial production process.
In order to achieve the purpose, the invention adopts the specific scheme that:
a method for measuring Fe content in a carbon-coated SiO lithium battery negative electrode material comprises the following steps:
step one, preparation of a sample solution: weighing 0.1-0.3 g of carbon-coated SiO lithium battery negative electrode material, putting the carbon-coated SiO lithium battery negative electrode material into a microwave digestion tank, sequentially adding 2-3 mL of ultrapure water, 2-4 mL of hydrofluoric acid with the mass fraction of 40%, 3-5 mL of nitric acid with the mass fraction of 68% and 5-7 mL of hydrochloric acid with the mass fraction of 38% into the microwave digestion tank, after the reaction is finished, putting the microwave digestion tank into a microwave digestion instrument for microwave digestion, cooling the solution subjected to microwave digestion to room temperature, transferring the solution into a beaker, cleaning the microwave digestion tank with the ultrapure water, pouring the cleaning solution into the beaker together, heating to remove the acid until the amount of the mixed solution is 2-5 mL, cooling to the room temperature, transferring the mixed solution into a volumetric flask, adding the ultrapure water to the 100mL scale mark of the volumetric flask, and then carrying out constant volume filtration to obtain a sample solution;
step two, preparing blank liquid and standard working solution: the blank liquid is a sample solution obtained in the step one under the condition that the national standard Fe element standard liquid and the sample are not added, namely the blank liquid; the standard working solution is prepared by taking a national standard sample Fe element standard solution with the concentration of 100mg/L as a single standard stock solution, pouring 0 muL, 200 muL, 500 muL, 1000 muL and 2000 muL of the single standard stock solution into 5 volumetric flasks respectively, and adding ultrapure water to a constant volume of 100mL of the volumetric flasks to obtain 5 standard solutions with the concentrations of 0mg/L, 0.2mg/L, 0.5mg/L, 1mg/L and 2 mg/L;
step three, drawing a standard working curve: selecting an 259.940 wavelength spectral line as an analysis spectral line of Fe element, measuring the Fe intensity in the standard working solution by using an inductively coupled plasma emission spectrometer, and then drawing a standard working curve by using the Fe intensity value as a vertical coordinate and the Fe mass concentration as a horizontal coordinate;
step four, measuring the mass concentration of the Fe element: measuring the strength of Fe in the sample solution and the blank solution respectively by using an inductively coupled plasma emission spectrometer, wherein the corresponding concentration value of the strength value of Fe on a standard working curve is the mass concentration of the Fe element;
step five, calculating the content of Fe element: calculating the percentage content w of Fe element according to the following formula:
wherein ρ represents the mass concentration of Fe element in the sample solution, and ρ0The mass concentration of Fe element in the blank liquid is shown, V represents the volume of the sample solution, and m represents the mass of the sample.
Further, in the first step, the specific steps of placing the microwave digestion tank in a microwave digestion instrument for microwave digestion are as follows: heating to 120 deg.C, and maintaining for 3min under 15 bar; heating to 160 deg.C, maintaining for 5min at 30 bar; then the temperature is reduced to 50 ℃ and kept for 3 min.
Further, in the first step, the temperature for heating and acid-expelling is 90 ℃.
Further, the operating parameters of the inductively coupled plasma atomic emission spectrometer are as follows:
power: 1.1 KW;
light chamber temperature: 35 ℃;
cooling gas: 14 LPM;
auxiliary gas: 0.2 LPM;
atomizing: 32 PSI;
pump speed: 35 RPM;
detector operating temperature: -38 ℃.
Has the advantages that:
the method fills the technical blank of the method for measuring the Fe content in the carbon-coated SiO lithium battery cathode material, and dissolves the carbon-coated SiO lithium battery cathode material by using a hydrofluoric acid-nitric acid-hydrochloric acid composite acid system and adopting a microwave digestion pretreatment method, so that the method can reduce the use amount of a test material and strong acid, fully dissolve the test material, and has the advantages of short time, high efficiency, and simple and safe operation. In addition, in the process of heating and acid removing, the Si substrate and F in the sample generate silicon tetrafluoride along with steam escape, so that the consistency of the substrate of the solution for establishing the standard curve and the substrate of the sample solution to be detected is ensured, and the influence of the substrates is not eliminated by using a substrate correction method. The method can be used for rapidly, efficiently, accurately and stably measuring the trace Fe in the carbon-coated SiO lithium battery cathode material, and can be widely applied to monitoring the content of impurity Fe in the carbon-coated SiO lithium battery cathode material product in the industrial production process.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.
A method for measuring Fe content in a carbon-coated SiO lithium battery negative electrode material comprises the following steps:
step one, preparation of a sample solution: weighing 0.1-0.3 g of carbon-coated SiO lithium battery negative electrode material, placing the carbon-coated SiO lithium battery negative electrode material into a microwave digestion tank, sequentially adding 2-3 mL of ultrapure water, 2-4 mL of hydrofluoric acid with the mass fraction of 40%, 3-5 mL of nitric acid with the mass fraction of 68% and 5-7 mL of hydrochloric acid with the mass fraction of 38% into the microwave digestion tank, after the reaction is finished, placing the microwave digestion tank into a microwave digestion instrument for microwave digestion, firstly heating to 120 ℃, keeping the temperature for 3min, and keeping the pressure at 15 bar; heating to 160 deg.C, maintaining for 5min at 30 bar; then cooling to 50 ℃, keeping for 3min, transferring the solution after microwave digestion to a beaker after cooling to room temperature, cleaning a microwave digestion tank with ultrapure water, pouring the cleaning solution into the beaker together, driving acid at 90 ℃ until the amount of the mixed solution is 2-5 mL, cooling to room temperature, transferring the mixed solution to a volumetric flask, fixing the volume to the 100mL scale mark of the volumetric flask with ultrapure water, and then filtering to obtain a sample solution;
step two, preparing blank liquid and standard working solution:
the blank liquid is a sample solution obtained in the step one under the condition that the national standard Fe element standard liquid and the sample are not added, namely the blank liquid;
the standard working solution is prepared by taking a national standard sample Fe element standard solution with the concentration of 100mg/L as a single standard stock solution, pouring 0 muL, 200 muL, 500 muL, 1000 muL and 2000 muL of the single standard stock solution into 5 volumetric flasks respectively, and adding ultrapure water to a constant volume of 100mL of the volumetric flasks to obtain 5 standard solutions with the concentrations of 0mg/L, 0.2mg/L, 0.5mg/L, 1mg/L and 2 mg/L;
step three, drawing a standard working curve: the working parameters of the inductively coupled plasma atomic emission spectrometer are as follows: power: 1.1 KW; light chamber temperature: 35 ℃; cooling gas: 14 LPM; auxiliary gas: 0.2 LPM; atomizing: 32 PSI; pump speed: 35 RPM; detector operating temperature: -38 ℃; selecting an 259.940 wavelength spectral line as an analysis spectral line of Fe element, measuring the Fe intensity in the standard working solution by using an inductively coupled plasma emission spectrometer, and then drawing a standard working curve by using the Fe intensity value as a vertical coordinate and the Fe mass concentration as a horizontal coordinate; it should be noted that the correlation coefficient R of the drawn standard working curve needs to be not less than 0.9950, and if not, the standard working curve of Fe needs to be redrawn;
step four, measuring the mass concentration of the Fe element: measuring the strength of Fe in the sample solution and the blank solution respectively by using an inductively coupled plasma emission spectrometer, wherein the corresponding concentration value of the strength value of Fe on a standard working curve is the mass concentration of the Fe element;
step five, calculating the content of Fe element: calculating the percentage content w of Fe element according to the following formula:
wherein ρ represents the mass concentration (. mu.g/mL) of Fe element in the sample solution, and ρ0The mass concentration (. mu.g/mL) of Fe element in the blank solution is shown, V is the volume (mL) of the sample solution, and m is the mass (g) of the sample.
The instrument used in the invention: prodigy7 inductively coupled plasma emission spectrometer, Leyman, USA, BerghofSpeedWave-Xpert microwave digestion apparatus, Sadolis BT125D electronic analytical balance.
Reagents used in the invention: hydrofluoric acid, nitric acid and hydrochloric acid are all super-grade purities, and the used ultrapure water is ultrapure water (with the resistivity of 18.25M omega cm) meeting the national first-grade standard; the concentration of the Fe single-standard stock solution is 100mg/L (GNM-SFE-002-2013) which is provided by the national analysis and test center of nonferrous metals and electronic materials.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The best working parameters of the inductively coupled plasma atomic emission spectrometer are as follows: power: 1.1 KW; light chamber temperature: 35 ℃; cooling gas: 14 LPM; auxiliary gas: 0.2 LPM; atomizing: 32 PSI; pump speed: 35 RPM; detector operating temperature: -38 ℃.
A method for measuring Fe content in a carbon-coated SiO lithium battery negative electrode material specifically comprises the following steps:
step one, preparation of a sample solution: weighing 0.1g of carbon-coated SiO material battery negative electrode material, placing the battery negative electrode material into a polytetrafluoroethylene microwave digestion tank liner, enabling a test material to flow into the tank bottom along the tank wall by using 2-3 mL of ultrapure water, sequentially adding 3mL of hydrofluoric acid, 3mL of nitric acid and 5mL of hydrochloric acid at room temperature, placing the battery negative electrode material into a digestion tank outer tank after the reaction is calm, screwing down the digestion tank and shaking up the digestion tank, placing the digestion tank into a microwave digestion instrument for digestion, heating the digestion tank to 120 ℃ firstly, keeping the temperature for 3min, and keeping the pressure at 15 bar; heating to 160 deg.C, maintaining for 5min at 30 bar; then the temperature is reduced to 50 ℃ and kept for 3 min. Taking out the digestion tank when the digestion is finished and the temperature is up to room temperature, opening the digestion tank under a fume hood (the air outlet of the digestion tank cannot be aligned with a person), pouring the solution into a polytetrafluoroethylene beaker, pouring water for purging the tank cover and the inner wall of the pipe by using ultrapure water into the polytetrafluoroethylene beaker, placing the polytetrafluoroethylene beaker on an electric heating plate, removing acid at the temperature of 90 ℃ until the amount of the mixed solution is 2-5 mL, cooling to room temperature, transferring the mixed solution into a volumetric flask, fixing the volume to the 100mL scale line of the volumetric flask by using the ultrapure water, and filtering to obtain a sample solution;
step two, preparing blank liquid and standard working solution:
the blank liquid is a sample solution obtained in the step one under the condition that the national standard Fe element standard liquid and the sample are not added, namely the blank liquid;
the standard working solution is prepared by taking a national standard sample Fe element standard solution with the concentration of 100mg/L as a single standard stock solution, pouring 0 muL, 200 muL, 500 muL, 1000 muL and 2000 muL of the single standard stock solution into 5 volumetric flasks respectively, and adding ultrapure water to a constant volume of 100mL of the volumetric flasks to obtain 5 standard solutions with the concentrations of 0mg/L, 0.2mg/L, 0.5mg/L, 1mg/L and 2 mg/L;
step three, drawing a standard working curve: selecting an 259.940 wavelength spectral line as an analysis spectral line of Fe element, measuring the Fe intensity in the standard working solution by using an inductively coupled plasma emission spectrometer, and then drawing a standard working curve by using the Fe intensity value as a vertical coordinate and the Fe mass concentration as a horizontal coordinate; the standard working curve equation of the Fe element is that y is 269382x +1166.1, and the correlation coefficient R is 0.9999;
step four, measuring the mass concentration of the Fe element: measuring the strength of Fe in a sample solution and a blank solution by using an inductively coupled plasma emission spectrometer, wherein the corresponding concentration value of the strength value of Fe on a standard working curve is the mass concentration of Fe element; and calculating the percentage content w of the Fe element according to the following formula:
wherein ρ represents the mass concentration (. mu.g/mL) of Fe element in the sample solution, and ρ0The mass concentration (. mu.g/mL) of Fe element in the blank solution is shown, V is the volume (mL) of the sample solution, and m is the mass (g) of the sample. The mass concentration of the Fe element in the measured sample solution and the calculated percentage content of Fe are detailed in table 1, wherein the numerical value of the measured value is determined by repeating the measurement for 5 times on the same carbon-coated SiO material battery negative electrode material.
TABLE 1 Mass concentration, percentage content and relative standard deviation of Fe element in sample solution
| Numbering | Measured value/ppm | Mean value of | Percentage content | RSD |
| 1 | 0.409、0.405、0.405、0.407、0.400 | 0.405ppm | 0.0405％ | 0.95％ |
| 2 | 1.031、1.041、1.033、1.031、1.034 | 0.99ppm | 0.1034％ | 0.35％ |
As can be seen from Table 1, the Relative Standard Deviation (RSD) of the negative electrode materials of the two carbon-coated SiO batteries is less than 1%, so that the measuring method has high precision and stable and reliable numerical values.
In order to verify the accuracy of the method for measuring the Fe content in the carbon-coated SiO material battery negative electrode material, 3 parts of solutions to be measured with different concentrations are prepared from a Fe single standard stock solution (GNM-SFE-002-.
TABLE 2 actual and measured Fe concentrations in Fe reference solution
To further verify and evaluate the accuracy of the assay method of the present invention, the assay method of the present invention was verified using normalized recovery using the same sample solution preparation method and assay conditions, using a Fe single standard stock solution concentration of 100mg/L (GNM-SFE-002-2013) as the standard addition material, and the results are shown in Table 3.
Table 3 recovery and repeatability of Fe in carbon coated SiO lithium battery negative electrode material (n ═ 5)
As can be seen from tables 2 and 3, the method for determining the Fe content in the carbon-coated SiO lithium battery negative electrode material provided by the invention has the advantages that the standard recovery rate is 90.2-93%, the RSD is 0.35-0.95%, and the standard recovery rate and the RSD are both in an allowable range. Therefore, the data stability, repeatability, accuracy and precision of the method for measuring the Fe content in the carbon-coated SiO lithium battery negative electrode material are high.
The foregoing is merely a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (4)
1. A method for measuring Fe content in a carbon-coated SiO lithium battery negative electrode material is characterized by comprising the following steps:
step one, preparation of a sample solution: weighing 0.1-0.3 g of carbon-coated SiO lithium battery negative electrode material, putting the carbon-coated SiO lithium battery negative electrode material into a microwave digestion tank, sequentially adding 2-3 mL of ultrapure water, 2-4 mL of hydrofluoric acid with the mass fraction of 40%, 3-5 mL of nitric acid with the mass fraction of 68% and 5-7 mL of hydrochloric acid with the mass fraction of 38% into the microwave digestion tank, after the reaction is finished, putting the microwave digestion tank into a microwave digestion instrument for microwave digestion, cooling the solution subjected to microwave digestion to room temperature, transferring the solution into a beaker, cleaning the microwave digestion tank with the ultrapure water, pouring the cleaning solution into the beaker together, heating to remove the acid until the amount of the mixed solution is 2-5 mL, cooling to the room temperature, transferring the mixed solution into a volumetric flask, using the ultrapure water to reach the 100mL scale mark of the volumetric flask, and then carrying out constant volume filtration to obtain a sample solution;
step two, preparing blank liquid and standard working solution:
the blank liquid is a sample solution obtained in the step one under the condition that the national standard Fe element standard liquid and the sample are not added, namely the blank liquid;
the standard working solution is prepared by taking a national standard sample Fe element standard solution with the concentration of 100mg/L as a single standard stock solution, pouring 0 muL, 200 muL, 500 muL, 1000 muL and 2000 muL of the single standard stock solution into 5 volumetric flasks respectively, and adding ultrapure water to a constant volume of 100mL of the volumetric flasks to obtain 5 standard solutions with the concentrations of 0mg/L, 0.2mg/L, 0.5mg/L, 1mg/L and 2 mg/L;
step three, drawing a standard working curve: selecting an 259.940 wavelength spectral line as an analysis spectral line of Fe element, measuring the Fe intensity in the standard working solution by using an inductively coupled plasma emission spectrometer, and then drawing a standard working curve by using the Fe intensity value as a vertical coordinate and the Fe mass concentration as a horizontal coordinate;
step four, measuring the mass concentration of the Fe element: measuring the strength of Fe in the sample solution and the blank solution respectively by using an inductively coupled plasma emission spectrometer, wherein the corresponding concentration value of the strength value of Fe on a standard working curve is the mass concentration of the Fe element;
step five, calculating the content of Fe element: calculating the percentage content w of Fe element according to the following formula:
wherein ρ represents the mass concentration of Fe element in the sample solution, and ρ0The mass concentration of Fe element in the blank liquid is shown, V is the volume of the sample solution, and m is the mass of the sample.
2. The method for determining the Fe content in the carbon-coated SiO lithium battery negative electrode material according to claim 1, wherein in the first step, the specific steps of placing the microwave digestion tank in a microwave digestion instrument for microwave digestion are as follows: heating to 120 deg.C, and maintaining for 3min under 15 bar; heating to 160 deg.C, maintaining for 5min at 30 bar; then the temperature is reduced to 50 ℃ and kept for 3 min.
3. The method as claimed in claim 1, wherein the temperature for heating to remove acid in the first step is 90 ℃.
4. The method for determining the Fe content in the carbon-coated SiO lithium battery cathode material as claimed in claim 1, wherein in the third step or the fourth step, the working parameters of the inductively coupled plasma atomic emission spectrometer are as follows:
power: 1.1 KW;
light chamber temperature: 35 ℃;
cooling gas: 14 LPM;
auxiliary gas: 0.2 LPM;
atomizing: 32 PSI;
pump speed: 35 RPM;
detector operating temperature: -38 ℃.
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| CN202010538727.0A CN111638206A (en) | 2020-06-13 | 2020-06-13 | Method for measuring Fe content in carbon-coated SiO lithium battery negative electrode material |
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| CN202010538727.0A CN111638206A (en) | 2020-06-13 | 2020-06-13 | Method for measuring Fe content in carbon-coated SiO lithium battery negative electrode material |
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| CN117367934A (en) * | 2023-10-16 | 2024-01-09 | 南京汉欣医药科技有限公司 | Microwave digestion-ICP-OES (inductively coupled plasma-optical emission spectrometry) vitamin K determination 1 Method for preparing medium iron ions |
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