Combined Thermal Runaway Investigation of Coin Cells with an Accelerating Rate Calorimeter and a Tian-Calvet Calorimeter

Abstract

Commercial coin cells with LiNi0.6Mn0.2Co0.2O2 positive electrode material were investigated using an accelerating rate calorimeter and a Tian-Calvet calorimeter. After cycling and charging to the selected states of charge (SOCs), the cells were studied under thermal abuse conditions using the heat-wait-seek (HWS) method with the heating step of 5 K and a threshold for self-heating detection of 0.02 K/min. The onset temperature and the rate of the temperature rise, i.e., the self-heating rate for thermal runaway events, were determined. The morphology of the positive electrode, negative electrode and the separator of fresh and tested cells were compared and investigated with scanning electron microscopy (SEM). Furthermore, the microstructure and the chemical compositions of the individual components were investigated by X-ray diffraction (XRD) and inductively coupled plasma with optical emission spectrometry (ICP-OES), respectively. In the Tian-Calvet calorimeter, the coin cells with the selected SOCs and the individual components (positive electrode, negative electrode and separator) were heated up with a constant heating rate of 0.1 °C/min (ramp heating mode). Simultaneously, the heat flow signals were recorded to analyze the heat generation. The combination of the three different methods—the HWS method using the ES-ARC, ramp heating mode on both cells and the individual components using the Tian-Calvet calorimeter—together with a post-mortem analysis, give us a complete picture of the processes leading to thermal runaway.

Toxicity, Emissions and Structural Damage from Lithium-Ion Battery Thermal Runaway

“…Abuse (overcharge, internal short circuit and external short circuit, hot stove) will accelerate the generation of internal heat of LIBs, and lagging of heat transmission will cause rapid accumulation of internal heat of the battery, which will eventually lead to thermal runaway of the battery [18][19][20][21][22][23]. By studying the decomposition and mutual reactions of various components in the battery, it can be seen that the thermal stability of LIB materials is the basis of safety [24][25][26][27].…”