M. Trujillo, V. Rikka, W.S. Tang, J. Jeevarajan
UL Research Institutes - Electrochemical Research Institute,
United States
Keywords: safety, lithium ion batteries, electrolyte, thermal analysis, GC-TOF MS, TGA-DSC
Summary:
Although the world is decreasing its dependency on fossil fuels, increasing energy demand for electronic devices and electrochemical storage has become prevalent. In addition, the growing use and requirements of these systems, for example, energy density, cycle life, and fast charging conditions, drives the need to understand the material- and cell-level safety of current and future battery chemistries. This study presents the thermochemical analysis of commercial lithium-ion battery materials: nickel-manganese-cobalt-containing lithium metal oxide cathode, graphite anode, conventional liquid electrolyte, and polymer separator membrane. Using different techniques, including Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), coupled with Gas Chromatography Time-of-Flight Mass Spectrometry (GC-TOFMS), the decomposition mechanisms and thermal stability of these materials are determined. By correlating the observed weight loss, heat flow, and gas emissions, we can precisely map safety hazards, such as: electrolyte decomposition, interfacial reactions, and thermal runaway under various high-stress conditions like fast charging and deep discharges, especially when individual components are combined into the micro-cell format. Similar studies, extended to investigate future technologies like solid-state and sodium-ion batteries, allows the systematic development of a database for materials safety assessment.