CN1621808A

CN1621808A - Method for measuring lithium salt in lithium ion battery electrolyte

Info

Publication number: CN1621808A
Application number: CNA2004100661744A
Authority: CN
Inventors: 艾玉玲
Original assignee: Zhangjiagang Guotai Huarong New Chemical Materials Co Ltd
Current assignee: Zhangjiagang Guotai Huarong New Chemical Materials Co Ltd
Priority date: 2004-12-10
Filing date: 2004-12-10
Publication date: 2005-06-01

Abstract

The process of measuring lithium ion concentration inside electrolyte of lithium ion cell includes the following steps: obtaining absorbency values A's of standard lithium ion solutions of different concentration C's by means of atomic absorption analysis; drawing C-A curve according to the A's corresponding to different C's; diluting the sample to be tested with absolute alcohol to make the concentration value in the middle section of the standard curve and performing the atomic absorption analysis of the diluted sample to obtain the absorbency values of the diluted sample; obtaining the lithium ion concentration of the diluted sample in the C-A curve and calculating the lithium ion concentration of the sample to be tested based on the lithium ion concentration of the diluted sample and the dilution multiple. The said process has relatively high precision.

Description

Lithium salts assay method in the lithium-ion battery electrolytes

Technical field

The present invention relates to a kind of method of measuring lithium salt in the lithium-ion battery electrolytes.

Background technology

For lithium-ion battery electrolytes, because lithium salt difference wherein, performances such as its conductivity also can be different, and can directly have influence on the quality of product, so lithium salt is a key index to lithium-ion battery electrolytes.Can select the method for suitable mensuration lithium salt for use, will be to the monitoring of lithium-ion battery electrolytes production run, guarantee that prescription is correct and the analysis of lithium salts in the unknown electrolytic solution all had important effect.

Summary of the invention

The present invention will provide a kind of method that can more accurately measure lithium salt in the lithium-ion battery electrolytes.

The technical solution used in the present invention is: described method mainly may further comprise the steps:

(1) gets the lithium standard solution of some variable concentrations values, respectively they are analyzed, obtain absorbance A separately with atomic absorption spectrophotometer (AAS); Make the C-A curve according to their concentration value C separately and corresponding absorbance A then;

(2) according to the density of lithium-ion battery electrolytes sample to be measured, this testing sample is diluted with absolute ethyl alcohol, make its concentration value be arranged in the intermediate range section of described some variable concentrations values of step (); Again in step () under the same condition, analyze with the sample of atomic absorption spectrophotometer (AAS) after dilution, obtain its absorbance A; According to the C-A curve in the step (), try to achieve the lithium salt C in this dilute sample then ₀

(3) at last calculate lithium salt (mol/L) in the testing sample according to following formula

C = \frac{C_{0} \times P}{6.941 \times 1000}

In the formula: C ₀: the lithium salt value (mg/L) in the dilute sample

P: diluted sample multiple

6.941: the atomic weight of lithium.

Advantage of the present invention is: use described method, the result's who tries to achieve precision is higher.

Description of drawings

Fig. 1 is the C-A curve map of lithium salt value C and absorbance A.

Embodiment

The present invention is further described by the following embodiment.

Example:

1, gets the lithium standard solution of 1g/L, it is diluted to the standard solution that concentration is respectively 0.5mg/L, 1.0mg/L, 1.5mg/L with absolute ethyl alcohol.

2, respectively the standard solution after the above-mentioned dilution is carried out atomic absorption analysis with atomic absorption spectrophotometer (AAS) then, and make the C-A curve map, as shown in Figure 1 according to their concentration value C separately and corresponding absorbance A;

3, get two kinds of lithium-ion battery electrolytes to be measured, its major parameter and extension rate see the following form:

	Density (g/cm ³)	Lithium salt (mol/L)	Extension rate
	Density (g/cm ³)	Lithium salt (mol/L)	Extension rate	Electrolytic solution 1	??1.045	?0.75(LiClO ₄)	?5000
Electrolytic solution 2	??1.235	?1.00(LiPF ₆)	?6250	Electrolytic solution 1	??1.045	?0.75(LiClO ₄)	?5000

4, with the same condition of step 2 under, respectively the electrolytic solution to be measured after the above-mentioned dilution is carried out atomic absorption analysis with atomic absorption spectrophotometer (AAS), obtain their absorbance A respectively, concrete data see the following form:

	??0.5mg/L	??1.0mg/L	??1.5mg/L	Diluted sample 1	Diluted sample 2
	??0.5mg/L	??1.0mg/L	??1.5mg/L	Diluted sample 1	Diluted sample 2	Absorbance	??0.1409	??0.2642	??0.3871	??0.2810	?0.2961
Working sample lithium salt (mol/L)				??0.77	?1.02	Absorbance	??0.1409	??0.2642	??0.3871	??0.2810	?0.2961

5 and then respectively according to absorbance A and C-A curve shown in Figure 1, try to achieve the lithium salt C of the electrolytic solution to be measured after the dilution respectively ₀Use formula of the present invention to calculate the lithium salt C of electrolytic solution to be measured respectively again.That is:

Sample 1:C=(0.2810-0.0179) * 5000/ (0.2462 * 6941)=0.77mol/L

Sample 2:C=(0.2961-0.0179) * 6250/ (0.2462 * 6941)=1.02mol/L

This shows, measure lithium salt in the lithium-ion battery electrolytes with method of the present invention, can satisfy ± error requirements of 0.05mol/L, precision is higher.

Claims

1, lithium salts assay method in the lithium-ion battery electrolytes is characterized in that: mainly may further comprise the steps:

(2) according to the density of lithium-ion battery electrolytes sample to be measured, this testing sample is diluted with absolute ethyl alcohol, make its concentration value be arranged in the intermediate range section of described some variable concentrations values of step (); Again in step () under the same condition, analyze with the sample of atomic absorption spectrophotometer (AAS) after dilution, obtain its absorbance A; According to the C-A curve in the step (), try to achieve the lithium salt value C in this dilute sample then ₀

(3) at last calculate lithium salt value C (mol/L) in the testing sample according to following formula

C = \frac{C_{0} \times P}{6.941 \times 1000}

In the formula: C ₀: the lithium salt value (mg/L) in the dilute sample,

P: the diluted sample multiple,

6.941: the atomic weight of lithium.