Standards Development

Scope

This document specifies a method for the determination of anions content of lithium hexafluorophosphate (LiPF6) by Ion Chromatography(IC).This document is applicable to the determination of impurity anions such as chloride(Cl-)and sulfate(SO42-). The limits of detection(LOD) for each anion are 0.1mg/kg and 0.3mg/kg, respectively.

This method is suitable for the laboratory operation of LiPF6 producer, final user and independent test institute.

Purpose

Lithium hexafluorophosphate (LiPF6) is mainly used as electrolyte lithium salt for lithium-ion battery (LIB). It is most commonly used salt in LIB and costs more than 50% of the electrolyte. Nowadays, there are more than 26 LiPF6 manufactures, with large demand and trading volume over the world. The impurity anions of LiPF6, such as chloride(Cl-), and sulfate(SO42-) originate from production and have the ability to combine with metal ions in cathode and anode, which can cause aluminum and copper current collector corrosion, cathode active material dissolution, anode active material exfoliation, and thus can affect the stability of SEI film, increase the side reaction, reduce the reversible capacity of battery and deteriorate the battery performance.

Therefore, the content of impurity anions in LiPF6 is an important index to monitor product quality. Ion Chromatography is one of the most commonly used ion detection method. It was created in the 1970s, and after nearly half century’s development, it has been widely applied in different fields. As for lithiumion battery electrolyte, Both the producer and downstream customer have a demand for using IC to determine LiPF6, and the method has been gained industry recognition and widely use over the world. The advantages of determination of LiPF6 impurity anions by IC are simple sample-pretreatment, high accuracy, low detection limit, reproducible and capable to detect multiple anions simultaneously.

It is our vision to promote the use of IC to determine anions in LiPF6 in the form of international standard, providing a unified quality evaluation basis for producer, downstream customer and regulatory authority in various countries, and facilitating wider communication and trade among enterprises over the world.