Separation and Quantification of Organic Electrolyte Components in Lithium-Ion Batteries via a Developed HPLC Method

Abstract

The development of a High Performance Liquid Chromatography (HPLC) method with an ultraviolet/visible light (UV/VIS) detector for the separation and quantification of organic carbonates, which are used in common organic carbonate-based electrolyte systems in lithium-ion batteries, is explored. The limit of detection, the limit of quantification as well as the linear range of the developed HPLC-UV/VIS method are reported. Furthermore, the HPLC was coupled to an electrospray ionization mass spectrometer (ESI-MS), also using the atmospheric pressure chemical ionization (APCI)-MS mode, for clear identification of analytes. Object of investigation are pure organic carbonates and thermally aged electrolytes. For the purpose of thermal aging, different electrolyte samples are stored at least one week at selected different temperatures. In addition, the HPLC method is compared to an established gas chromatography with flame ionization detector (GC-FID) and mass spectrometer (GC-MS) method that is also used for the separation, identification and quantification of organic carbonates. For comparison of the GC and HPLC method, an extracted fresh electrolyte out of an EV lithium ion cell was analyzed with both techniques. The developed HPLC method is more sensitive toward electrolyte additives and impurities e.g. vinylene carbonate (VC), Tetrabromobisphenol A (TBBA) and N-Methyl-2-pyrrolidone (NMP) compared to the existing GC method, and is therefore an important and complementary method for the analysis for electrolytes, especially for electrolyte additives.

Identification and formation mechanism of individual degradation products in lithium‐ion batteries studied by liquid chromatography/electrospray ionization mass spectrometry and atmospheric solid analysis probe mass spectrometry

“…. The carbonate and PEO oligomers were detected as degradation products of LiPF 6 and carbonate‐based LIB electrolytes in previous studies . Their estimated formation mechanisms are shown in Fig.…”

“…In recent years, GC/MS has been used to detect the formation of ethylene bis‐carbonates and to investigate the passivation ability and dissolution of the SEI formed on the negative electrode material . The formation of bis‐carbonates was investigated by high‐performance LC (HPLC)‐UV/VIS . Additionally, products of ionic thermal aging and hydrolysis of LiPF 6 in commercial LIB electrolytes were determined by ion chromatography (IC), IC/inductively coupled plasma optical emission spectroscopy (ICP‐OES) and IC/ESI‐MS .…”

A New Method for Determining the Concentration of Electrolyte Components in Lithium-Ion Cells, Using Fourier Transform Infrared Spectroscopy and Machine Learning

“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20] These instruments are costly, and these methods require the preparation and measurement of many calibration solutions. Often the columns or detectors used in chromatography experiments cannot be exposed to the high temperature decomposition products of LiPF 6 , so these experiments often focus on the organic portions of the electrolyte, after the water-soluble portions of the electrolyte have been removed.…”

Investigation of the Storage Behavior of Shredded Lithium‐Ion Batteries from Electric Vehicles for Recycling Purposes

“…LIBs loose capacity over time owing to different aging phenomena . Various reports focused on method development for aging investigations of different cell components and the electrolyte are available in the literature . However, aging of LIBs is not only related to cycle life, but concerns also the formation of hazardous or corrosive compounds in the cell during aging.…”

“…[27] Various reports focusedo nm ethod development for aging investigationso fd ifferent cell components [28][29][30][31][32] and the electrolyte are availablei nt he literature. [12,16,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] However, aging of LIBs is not only related to cyclel ife, but concerns also the formation of hazardous or corrosive compounds in the cell duringa ging. The formation of hydrofluorica cid, phosphoric acid, and alkyl fluorophosphate derivativesi sd emonstrated by different researchers.…”