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CN-121978255-A - Analysis method of lithium battery electrolyte

CN121978255ACN 121978255 ACN121978255 ACN 121978255ACN-121978255-A

Abstract

The application discloses an analysis method of lithium battery electrolyte, which relates to the technical field of lithium battery electrolyte analysis and comprises the following steps of S1, collecting a lithium battery electrolyte sample under an inert atmosphere, preprocessing the sample to obtain diluent to be tested, S2, injecting the diluent to be tested into an analysis and detection system to obtain characteristic response signals of all components in the lithium battery electrolyte, S3, calculating the content of a target component based on a preset quantitative analysis model and combining the characteristic response signals, S4, detecting the free acid content in the electrolyte, S5, detecting trace moisture in the electrolyte, and S6, feeding back and evaluating data. The application can solve the problems of easy degradation of sensitive components of the electrolyte and quantitative deviation caused by volatilization of the solvent, realize the integrated accurate analysis of organic and inorganic components, and remarkably improve the product consistency and data fidelity in the production process of the lithium battery electrolyte by matching with the embedded closed loop feedback logic.

Inventors

  • He Suiqun
  • WANG YUJIAO

Assignees

  • 陕西中丰动力能源有限公司

Dates

Publication Date
20260505
Application Date
20260408

Claims (10)

  1. 1. The analysis method of the lithium battery electrolyte is characterized by comprising the following steps of: s1, collecting a lithium battery electrolyte sample under an inert atmosphere, and preprocessing the sample to obtain a diluent to be tested; S2, injecting the diluent to be detected into an analysis and detection system to obtain characteristic response signals of all components in the lithium battery electrolyte; step S3, calculating the content of the target component by combining the characteristic response signals based on a preset quantitative analysis model, wherein the quantitative analysis model introduces a solvent degradation correction factor The calculation formula is as follows: ; Wherein, the For the mass fraction of the target component, Is the characteristic peak area of the target component, The mass of the internal standard is the mass of the internal standard, Is the characteristic peak area of the internal standard substance, For the quality of the sample, As a relative correction factor to be used, Is a solvent degradation correction factor; s4, detecting the content of free acid in the electrolyte; s5, detecting trace moisture in the electrolyte; and S6, data feedback and evaluation.
  2. 2. The method according to claim 1, wherein the specific sub-step of preprocessing the sample in step S1 comprises: S11, placing the collected electrolyte sample in a low-temperature environment of-20 ℃ to-10 ℃ for standing for 10min to 15min; s12, adding an anhydrous organic diluent into the sample after standing, wherein the volume ratio of the anhydrous organic diluent to the sample is (5-10): 1; S13, adding an internal standard solution with the mass concentration of 0.5 to 1.2 percent, shaking and uniformly mixing, and then passing through a solution mixer of 0.22 percent The organic filter membrane of (2) to be tested is obtained.
  3. 3. The method according to claim 1, wherein the specific substep of obtaining the characteristic response signal in step S2 includes: S21, separating the organic solvent component by utilizing a gas chromatography, setting the initial temperature of a chromatographic column to be 40 ℃, and heating to 220 ℃ at a rate of 5-8 ℃ per minute; s22, scanning the separated components by using a mass spectrum detector to obtain the mass-to-charge ratio of each component and the corresponding ion flow intensity; and S23, synchronously detecting the metal cation intensity in the sample by using an inductively coupled plasma emission spectrometer.
  4. 4. The method of claim 1, wherein the solvent degradation correction factor The calculation mode of (2) is as follows: ; Wherein, the Is the first The volatility coefficient of the seed solvent component, For the viscosity change of the component during analysis, In order to analyze the absolute temperature of the environment, To analyze the real-time pressure within the system.
  5. 5. The method according to claim 1, wherein the sub-step of calculating the target component content in step S3 comprises: S31 extracting characteristic peak area Peak area of internal standard And determining a relative correction factor according to the standard curve in S32 ; S32, establishing a linear regression equation according to a standard sample with known concentration, wherein the linear correlation coefficient of the linear regression equation is as follows: ; s33, substituting the characteristic response signals into the quantitative analysis model to calculate the percentage content of each solvent component and additive.
  6. 6. The method according to claim 1, wherein the step S4 specifically includes: s41, taking 5mL of the diluent to be measured, and adding a neutral ethanol solvent for secondary dilution; S42, using bromothymol blue as an indicator, and using a sodium hydroxide standard solution with the concentration of 0.01mol/L to perform potentiometric titration; S43, calculating the mass percentage of hydrofluoric acid according to the jump point of the titration end point.
  7. 7. The method according to claim 1, wherein the step S5 specifically includes: s51, setting the sample injection amount to be 0.5g to 1.0g by adopting a Karl Fischer coulometry tester; S52, carrying out oxidation-reduction reaction on iodine generated by electrolysis and water in the sample, and measuring consumed electric quantity; s53, calculating the water content in the sample according to the product of the electrolysis current and time, wherein the detection limit is not higher than 1 。
  8. 8. The method according to claim 3, wherein the chromatographic column is a capillary column of polyethylene glycol fixing liquid, the length is 30m to 60m, the inner diameter is 0.25mm to 0.32mm, and the film thickness is 0.25 To 0.5 。
  9. 9. The method according to claim 1, wherein the internal standard in step S1 is selected from any one of di-n-propyl carbonate, adiponitrile and sulfolane.
  10. 10. The method according to claim 1, wherein the step S6 specifically includes: s61, comparing the calculated component content with a preset standard component range; and S62, if the deviation exceeds +/-2%, triggering an abnormal alarm and carrying out component supplement or waste treatment on the batch of electrolyte.

Description

Analysis method of lithium battery electrolyte Technical Field The invention relates to the technical field of lithium battery electrolyte analysis, in particular to a method for analyzing lithium battery electrolyte. Background With the rapid development of new energy automobiles and large-scale energy storage industries, the lithium battery is widely focused on safety and energy density as a core power source, the electrolyte is used as an important component of the lithium ion battery, the component composition, impurity content and chemical stability of the electrolyte directly determine the cycle life and electrochemical performance of the battery, and in order to ensure the consistency of battery products, the establishment of a set of high-precision and full-component electrolyte analysis and evaluation system becomes a key link in the fields of battery manufacturing and material research and development. The method mainly relies on gas chromatography, mass spectrometry and various titration technologies for detecting organic solvents, lithium salts, additives, trace moisture and free acid in electrolyte; the technical path aims to monitor the quality change of the electrolyte in the production, storage and use processes through quantitative identification of each component, and build the quality assurance capability oriented to high-performance battery manufacturing. In the prior art, in the aspect of full component analysis of electrolyte, sensitive components in the electrolyte are easy to be subjected to micro degradation or hydrolysis due to the influence of environmental factors in the normal temperature sampling and pretreatment processes, so that the problem that the component state of a sample to be detected is deviated from that of the original electrolyte is solved. Therefore, an analysis method of lithium battery electrolyte is now proposed to solve the above problems. Disclosure of Invention The invention mainly aims to provide an analysis method of lithium battery electrolyte, which aims to solve the problems in the background. In order to achieve the purpose, the technical scheme adopted by the invention is that the analysis method of the lithium battery electrolyte comprises the following steps: S1, sample collection and pretreatment collaborative stabilization, namely obtaining a lithium battery electrolyte sample through a sampling container under a controlled inert atmosphere environment, placing the sample in a preset low-temperature field to perform static balance, then introducing an anhydrous organic dilution medium and a specific internal standard component to mix and dilute, and separating insoluble particles through a microporous filtration barrier to obtain the diluent to be tested. S2, synchronously acquiring and separating multicomponent signals, namely conveying diluent to be detected to an analysis and detection flow path, carrying out spatial distribution arrangement on organic solvent components by utilizing a gas phase separation path, capturing molecular fragment characteristics of each component by a mass spectrum sensing array, and synchronously starting a plasma excitation flow path to acquire the emission spectrum intensity of metal cations in the electrolyte, so as to form a multi-dimensional characteristic response signal set. S3, component quantization based on degradation correction model, namely extracting peak physical quantity in characteristic response signals, substituting the peak physical quantity into a preset quantitative analysis model, wherein the quantitative analysis model introduces solvent degradation correction factorsAnd (3) performing compensation calculation on the mass distribution of the target component, wherein the calculation formula is as follows: ; Wherein, the For the mass fraction of the target component,Is the characteristic peak area of the target component,For the mass of the internal standard to be added,Is the characteristic peak area of the internal standard substance,For the initial acquisition quality of the sample,For the preset relative correction factor to be a,Is a solvent degradation correction factor aiming at environmental fluctuation and component volatilization. The inert atmosphere environment in the step S1 is further provided by a glove box filled with high-purity argon, a gas circulation purifying unit is integrated in the glove box, the content of active substances in the environment is reduced through an oxygen removal column and a water removal column, the sampling container is a light-proof glass bottle with a sealing gasket, in the pretreatment process, a sample stays in a low-temperature cold trap for a preset time to reduce the chemical activity of heat-sensitive lithium salt, the anhydrous organic diluent is one or more selected from acetonitrile, dichloromethane or n-hexane, the volume ratio of the diluent to the sample is set in a preset range, the internal standard is weighed through a precision el