Method for measuring content of ferrous iron and ferric iron in ferrous phosphate lithium anode material

Abstract

The invention discloses a method for measuring the content of ferrous iron and ferric iron in a ferrous phosphate lithium anode material, which is used for carrying out sample treatment and sample measurement under a protective atmosphere and comprises the following steps: measuring the content of the ferrous iron: dissolving the ferrous phosphate lithium anode material by using acid; then, when the pH of a solution is regulated to 2-9, adding phenanthroline to produce an orange complex with the ferrous iron; and carrying out a sample measurement process of measuring the absorbance of the orange complex by using a spectralphotometer, and measuring the content of the ferric iron: dissolving the ferrous phosphate lithium anode material by using the acid; when the pH of the solution is 1-3, adding sulfosalicylic acid to produce a purple complex with the ferric iron; and measuring the absorbance of the purple complex by using the spectralphotometer. The invention also discloses a protective atmosphere device designed to test the method for measuring the content of the ferrous iron and the ferric iron, which comprises an admission pipe, an exhaust pipe, a box body, an operating space and operating gloves, wherein the operating space is filled with inert gases, such as argon, helium, neon, nitrogen and carbon dioxide.

Description

technical field [0001] The invention relates to a method for detecting the quality of battery positive electrode materials, in particular to a method for detecting the content of divalent iron and ferric iron in the lithium iron phosphate positive electrode material. Background technique [0002] Compared with traditional lithium-ion batteries, lithium iron phosphate has become more and more popular in electric vehicles, power tools, energy storage devices, etc. due to its cheap price, environmental protection, good environmental compatibility, good cycle performance and high safety performance. ideal energy configuration. [0003] In the lithium iron phosphate positive electrode material, there is more or less trivalent iron as an impurity. The existence of ferric iron will increase the self-discharge of the lithium iron phosphate positive electrode material and decrease the specific capacity. Content is an important indicator to measure the performance of lithium iron pho...

AI Technical Summary

Problems solved by technology

[0005] The content of ferric iron in lithium ferrous phosphate is trace or trace amount, and the titration method only consumes less potassium dichromate, resulting in increased systematic errors and accidental errors. big

The above-mentioned public titration method has a complicated operation process and a long operation time

[0006] In the above disclosure, high mercury chloride is used to neutralize excess stannous chloride, mercury pollution is introduced, potassium dichromate is used for titration, chromium pollution is introduced, the above method will seriously affect the environment

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