Oxidative Electrolyte Solvent Degradation in Lithium‐Ion Batteries: An In Situ Differential Electrochemical Mass Spectrometry Investigation

Differential electrochemical mass spectrometry (DEMS) was used to study the electrochemical decomposition of organic carbonate electrolyte solutions at practical lithium metal oxide composite electrodes used in lithium‐ion batteries. For propylene carbonate (PC), evolution was detected at , and composite electrodes. The starting point of gas evolution was 4.2 V vs. at , whereas at and , evolution was observed only above 4.8 V vs. . In addition, various other volatile electrolyte decomposition products of PC were detected when using , , and carbon black electrodes. In ethylene carbonate/dimethylcarbonate, evolution was detected only at electrodes, again starting at about 4.2 V vs. . © 1999 The Electrochemical Society. All rights reserved.