ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) detection method for trace metal impurities in silicon-based organic electrolyte additive

Abstract

The invention provides an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) detection method for trace metal impurities in a silicon-based organic electrolyte additive, which comprises the following steps: sample pretreatment: adding the silicon-based organic electrolyte additive into a solvent, and dissolving to obtain a sample solution; optimizing instrument parameters: opening an ICP-OES detection instrument, setting the power, each gas flow, measurement time and calibration intensity value of the instrument, setting an observation position according to the strongest intensity value, and performing optical initialization; and testing: measuring the standard solution, establishing a standard curve, and measuring the to-be-tested sample after the calibration coefficient reaches more than 0.999. By optimizing a sample pretreatment process and instrument parameters, the technical problems of silicon substrate interference, insufficient sensitivity, poor plasma stability and the like are effectively solved. The method has the advantages of strong anti-interference performance, high sensitivity, good stability and the like, and is especially suitable for quality control of the lithium ion battery electrolyte additive.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry, specifically to a method for detecting trace metal impurities in silicon-based organic electrolyte additives for lithium-ion batteries, particularly suitable for the quantitative analysis of metal impurities in silicon-containing organic compounds such as silane phosphate esters. Background Technology

[0002] Lithium-ion batteries, as the core of modern electrochemical energy storage technology, have always had performance optimization as a key research focus. Silicon-based organic electrolyte additives, such as tris(trimethylsilane)phosphate (TMSP), have become crucial components of next-generation high-performance electrolytes due to their unique chemical properties, which can significantly improve battery rate performance and cycle stability. However, the presence of trace metal impurities (such as Na, Fe, and Cu) in the electrolyte can catalyze side reactions, accelerate electrolyte decomposition, and severely affect battery cycle life and safety performance. Therefore, establishing accurate and reliable methods for detecting metal impurities is crucial for ensuring battery quality.

[0003] Currently, the detection of metal impurities mainly employs spectroscopic analysis methods, including atomic absorption spectrometry (AAS), X-ray fluorescence spectrometry (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and inductively coupled plasma optical emission spectrometry (ICP-OES). Although existing ICP-OES technology has addressed the detection of metal elements in ordinary organic phases to some extent through direct dilution with organic solvents and optimization of carbon removal devices, it still faces key technical bottlenecks when analyzing silicon-based organic electrolytes, such as severe spectral interference from the silicon substrate, difficulty in balancing sensitivity and anti-interference capabilities, and poor plasma stability.

[0004] With the continuous improvement of the energy density of lithium-ion batteries, the requirements for controlling metallic impurities in electrolyte additives (such as TMPS) are becoming increasingly stringent. Existing detection methods can no longer meet this demand, and there is an urgent need to develop a new detection method that combines high anti-interference ability, high sensitivity, and good stability to provide reliable analytical technology support for the performance optimization and quality control of lithium-ion batteries. Summary of the Invention

[0005] To address the aforementioned technical bottlenecks, this invention innovatively provides an ICP-OES method for detecting trace metal impurities in silicon-based organic electrolyte additives.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: (1) Sample pretreatment: Add the silicon-based organic electrolyte additive to the solvent and dissolve it to obtain the sample solution; (2) Preparation of standard curve point solutions: Using a solvent system that matches the sample matrix, the multi-element mixed standard solution was diluted stepwise to prepare a series of standard points with concentrations of 0 ppm, 0.1 ppm, 0.2 ppm, 0.5 ppm and 1 ppm.

[0007] (3) Optimize instrument parameters: Turn on the instrument, set the instrument power, plasma gas flow rate, measurement time and other parameters, calibrate the intensity value, set the observation position according to the strongest intensity value, and perform optical initialization.

[0008] (4) Testing: Measure the standard solution, establish a standard curve, and ensure that the calibration coefficient reaches 0.999 or higher. Test the blank sample and the sample to be tested. Perform parallel analysis three times for each injection and record the average value. Preferably, the ICP instrument used in this invention is an Elmerkin 220, equipped with an organic oxygenation system, with argon as the carrier gas, oxygen as the reactant gas, and helium as the auxiliary gas.

[0009] Silicon-based organic electrolyte additives include, but are not limited to, tris(trimethylsilane) phosphate, tris(trimethylsilane) borate, bis(trimethylsilane) carbonate, and hexamethyldisilazane.

[0010] Preferably, the sample weight mentioned in the above scheme is 0.1 to 0.5 g.

[0011] Preferably, the solvents described in the above scheme include, but are not limited to, mixtures of N-methylpyrrolidone, acetonitrile, dichloromethane, dimethyl sulfoxide, etc., with water.

[0012] Preferably, the solvent added in the above scheme has a volume fraction of 90-98%, with the remainder being water.

[0013] Preferably, during the instrument detection process described in the above scheme, the plasma gas flow rate is 15-20 L / min, the nebulizer gas flow rate is 0.3-0.8 L / min, the auxiliary gas flow rate is 0.3-0.8 L / min, the oxygen flow rate is 30-50 mL / min, the sample injection peristaltic pump flow rate is 0.5-1.2 L / min, argon is used as the carrier plasma gas, oxygen is used as the reactant gas, and helium is used as the auxiliary gas.

[0014] The plasma gas flow rate is 15-18 L / min, the atomizer gas flow rate is 0.5-0.8 L / min, the auxiliary gas flow rate is 0.3-0.5 L / min, the oxygen flow rate is 40 mL / min, and the peristaltic pump flow rate is 0.8 L / min.

[0015] Preferably, the blank sample mentioned in the above scheme is a solution of the same solvent system.

[0016] The technical solution of the present invention has the following beneficial effects: 1. This invention exhibits good anti-interference properties: by controlling the sample volume and using a mixed system consisting of a high proportion of organic solvent and a small amount of water, spectral interference caused by the silicon substrate can be effectively suppressed. The organic solvent can dissolve silicon-based additives well, while the introduction of an appropriate amount of water helps to adjust the sample viscosity and surface tension, improve the atomization process, and reduce silicon-related spectral interference.

[0017] 2. This invention exhibits high sensitivity: the N-methylpyrrolidone (NMP) mixed system with water significantly improves sample atomization efficiency, resulting in more uniform aerosol particle size and thus enhancing the signal intensity of metal elements. The combination of low sample volume and high dilution factor suppresses matrix interference while ensuring sufficient detection sensitivity.

[0018] 3. This invention exhibits good stability: By optimizing the ratio of organic phase to water in the solvent, carbon buildup in the plasma torch and conical nozzle is effectively reduced. The addition of an appropriate amount of water increases solvent polarity, which helps stabilize the injection of organic samples and maintain plasma stability, thereby significantly improving the long-term stability of the testing system. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are only for illustrating the present invention and do not limit the scope of the present invention. Those skilled in the art can make some modifications and improvements based on the above-described invention.

[0020] Example 1 1. Sample pretreatment: Weigh 0.2 g of sample tris(trimethylsilane) phosphate in an inert atmosphere glove box, add 2 mL of N-methylpyrrolidone (NMP), shake well, remove the glove box and continue to add NMP to 9.5 mL, make up to 10 mL with deionized water, and shake the sample solution thoroughly.

[0021] 2. Preparation of standard curve spot solutions: Using a solvent system that matches the sample matrix, V(NMP):V(water) = 95:5, the multi-element mixed standard solution was diluted stepwise to prepare a series of standard spots with concentrations of 0 ppm, 0.1 ppm, 0.2 ppm, 0.5 ppm and 1 ppm.

[0022] 3. Instrument parameter optimization: Turn on the Elmerkin 220 instrument, set the instrument power to 1500 W, plasma gas flow rate to 17 L / min, nebulizer gas flow rate to 0.6 L / min, auxiliary gas flow rate to 0.4 L / min, oxygen flow rate to 40 mL / min, peristaltic pump flow rate to 0.8 L / min, argon as carrier gas, oxygen as reactant gas, and helium as auxiliary gas. Calibrate the intensity value, set the observation position according to the strongest intensity value, and perform optical initialization.

[0023] 4. Testing: Measure the multi-element standard solution, establish a standard curve, ensuring the calibration coefficient reaches 0.999 or higher, test blank samples and sample solutions, performing three parallel analyses for each injection, and finally recording the average value. Perform precision and spike recovery tests.

[0024] Example 2 1. Sample pretreatment: Weigh 0.2 g of sample bis(trimethylsilane) carbonate in an inert atmosphere glove box, add 2 mL of N-methylpyrrolidone (NMP), shake well, remove the glove box and continue to add NMP to 9.5 mL, make up to 10 mL with deionized water, and shake the sample solution thoroughly.

[0025] 2. Preparation of standard curve calibrator solution: Same as in Example 1.

[0026] 3. Instrument parameter optimization: Turn on the Elmerkin 220 instrument, set the instrument power to 1500 W, plasma gas flow rate to 17 L / min, nebulizer gas flow rate to 0.6 L / min, auxiliary gas flow rate to 0.4 L / min, oxygen flow rate to 40 mL / min, peristaltic pump flow rate to 0.8 L / min, argon as carrier gas, oxygen as reactant gas, and helium as auxiliary gas. Calibrate the intensity value, set the observation position according to the strongest intensity value, and perform optical initialization.

[0027] 4. Testing: Measure the multi-element content of the sample solution, performing three parallel analyses for each injection and recording the average value. Conduct precision and spike recovery tests.

[0028] Example 3 1. Sample pretreatment: Weigh 0.2 g of sample tris(trimethylsilane)borate in an inert atmosphere glove box, add 2 mL of N-methylpyrrolidone (NMP), shake well, remove the glove box and continue to add NMP to 9.5 mL, make up to 10 mL with deionized water, and shake the sample solution thoroughly.

[0029] 2. Preparation of standard curve calibrator solution: Same as in Example 1.

[0030] 3. Instrument parameter optimization: Turn on the Elmerkin 220 instrument, set the instrument power to 1500 W, plasma gas flow rate to 17 L / min, nebulizer gas flow rate to 0.6 L / min, auxiliary gas flow rate to 0.4 L / min, oxygen flow rate to 40 mL / min, peristaltic pump flow rate to 0.8 L / min, argon as carrier gas, oxygen as reactant gas, and helium as auxiliary gas. Calibrate the intensity value, set the observation position according to the strongest intensity value, and perform optical initialization.

[0031] 4. Testing: Measure the multi-element content of the sample solution, performing three parallel analyses for each injection and recording the average value. Conduct precision and spike recovery tests.

[0032] Comparative Example 1 In step 3, the plasma gas flow rate was 27 L / min, and the remaining steps, reagents, and instrument parameters were exactly the same as in Example 1. The multi-element content of the sample solution was measured, with each injection analyzed in triplicate, and the average value was recorded. Precision and spiked recovery were then tested.

[0033] Comparative Example 2 Except for changing the final dilution solvent to pure NMP (i.e., V(NMP):V(water) = 100:10), all other steps, reagents, and instrument parameters were exactly the same as in Example 1. The sample solutions were tested in triplicate for each injection, and the average value was recorded. Precision and spiked recovery were then tested.

[0034] Comparative Example 3 Except for shutting down the instrument's oxygen supply system (i.e., setting the oxygen flow rate to 40 mL / min), all other steps, reagents, and instrument parameters were identical to those in Example 1. The sample solutions were tested, with each injection analyzed in triplicate, and the average value was recorded. Precision and spike recovery were then performed.

[0035] As shown in Table 1, Examples 1, 2, and 3 exhibited high spike recoveries, low RSD%, and minimal signal drift, demonstrating that the method possesses good anti-interference capabilities, stability, and high sensitivity. Comparative Example 1 showed significantly higher recoveries and increased RSD, indicating that high silicon substrate loading induces strong non-spectral interference (such as ionization suppression and viscosity alteration affecting atomization) and spectral interference. The moderate sampling amount and high dilution factor controlled in this invention are crucial for ensuring accuracy. Comparative Examples 2 and 3 indicate that a lack of oxygen or the use of pure organic solvents leads to severe carbon buildup and drastic signal drift, indicating extreme plasma instability.

[0036] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0037] Table 1: Test Results of Examples and Comparative Examples .

Claims

1. An ICP-OES method for detecting trace metal impurities in silicon-based organic electrolyte additives, characterized in that, Includes the following steps: (1) Sample pretreatment: Add the silicon-based organic electrolyte additive to the solvent and dissolve it to obtain the sample solution; (2) Optimize instrument parameters: Turn on the ICP-OES detection instrument, set the instrument power, gas flow rate, measurement time, calibrate the intensity value, set the observation position according to the strongest intensity value, and perform optical initialization; (3) Testing: Measure the standard solution, establish a standard curve, and measure the sample to be tested after the calibration coefficient reaches 0.999 or higher.

2. The ICP-OES detection method for trace metal impurities in silicon-based organic electrolyte additives according to claim 1, characterized in that, Silicon-based organic electrolyte additives include any one of tris(trimethylsilane) phosphate, tris(trimethylsilane) borate, bis(trimethylsilane) carbonate, and hexamethyldisilazane.

3. The ICP-OES detection method for trace metal impurities in silicon-based organic electrolyte additives according to claim 1, characterized in that, The solvent includes any one of N-methylpyrrolidone, acetonitrile, dichloromethane, and dimethyl sulfoxide mixed with water.

4. The ICP-OES detection method for trace metal impurities in silicon-based organic electrolyte additives according to claim 3, characterized in that, The volume fraction of water is 1-5%.

5. The ICP-OES method for detecting trace metal impurities in silicon-based organic electrolyte additives according to claim 1, characterized in that, The volume fraction of the solvent added is 90-98%.

6. The ICP-OES method for detecting trace metal impurities in silicon-based organic electrolyte additives according to claim 5, characterized in that, Before detection, a solvent system matching the sample matrix was used to progressively dilute the multi-element mixed standard solution to prepare a series of standard points with concentrations of 0 ppm, 0.1 ppm, 0.2 ppm, 0.5 ppm, and 1 ppm.

7. The ICP-OES method for detecting trace metal impurities in silicon-based organic electrolyte additives according to claim 1, characterized in that, During the instrument's detection process, the plasma gas flow rate is 15-20 L / min, the nebulizer gas flow rate is 0.3-0.8 L / min, the auxiliary gas flow rate is 0.3-0.8 L / min, the reaction gas flow rate is 30-50 mL / min, and the peristaltic pump flow rate is 0.5-1.2 L / min.

8. The detection method according to claim 7, characterized in that, The plasma gas flow rate is 17 L / min, the atomizer gas flow rate is 0.6 L / min, the auxiliary gas flow rate is 0.4 L / min, the reaction gas flow rate is 40 mL / min, and the peristaltic pump flow rate is 0.8 L / min.

9. The detection method according to claim 8, characterized in that, The plasma gas is argon, the auxiliary gas is helium, and the reaction gas is oxygen.

10. The detection method according to any one of claims 1-9, characterized in that, Trace metal impurities include Fe and Na.