Analysis of Trialkyl Phosphates as Markers for Lithium Battery Aging

User Benefits

- Lithium Batteries (LIB) decomposition and aging can be evaluated by monitoring Trialkyl Phosphates. - A routine and fast GCMS method for the detection of Trialkyl Phosphates was developed. - Trialkyl Phosphates can be detected with high sensitivity and selectivity in commercial liquid electrolytes.

Introduction

The electrolyte solution is a crucial part of a typical Lithium-ion battery, consisting of Li salts (e.g. LiPF₆), and organic carbonates. Decomposition and formation of phosphorous-based and other organic products starts already at the production stage of the electrolyte. The formation of such molecules does not affect the electrolyte/battery quality negatively, as long as the quantity is low enough. On the contrary, several decomposition products have a positive effect on the formation of the so-called SEI surface (Solid Electrolyte Interface) on the LIB anodes, which is crucial for the battery functionality. Nevertheless, this is a continuous chemical process and the increasing amount of some of the decomposition products is a clear indicator of the progressive aging of the battery/electrolyte. This application is demonstrating the GCMS analysis of Trialkyl Phosphates as reaction products of carbonates and LiPF6 salt. The choice of this compounds as markers for electrochemical battery aging is due to the fact, that their formation is very slow and depends only on a few external parameters, allowing to investigate the electrochemical aging (charge/discharge) by a simple comparison of before/after analyte content.

August 7, 2024 GMT