A Comparative Study of Lithium-Ion Cathode Chemistry Correlations with Emissions Initiated by Nail Penetration Abuse in the Presence of an Immersive Coolant 2022-01-0715

Internal short-circuit in cells/batteries is a phenomenon where there is direct electrical contact between the positive and negative electrodes leading to thermal runaway. The nail penetration tests were used to simulate an internal short circuit within the battery, where a conductive nail was used to pierce the battery cell separator membrane which provided direct electrical contact between the positive and negative electrodes. The batteries tested during this work were common batteries used in existing automotive applications, and they included a nickel manganese cobalt (NMC) battery from a Chevrolet Bolt, a lithium manganese oxide (LMO) battery from a Chevrolet Volt, and a lithium iron phosphate (LFP) battery in a hybrid transit bus. The battery abuse and emissions tests were designed to intentionally drive the three different battery chemistries into thermal runaway while measuring battery temperatures, battery voltages and gaseous emissions. During this testing, the batteries were submerged in an immersive coolant, NOVEC 7300, in order to judge how effective, the immersive coolant was in preventing additional thermal propagation. The emissions data collected from FTIR (Fourier Transform Infrared Spectroscopy), GC-FID (Gas Chromatography and Flame Ionization Detection) and AES (Atomic Emission Spectroscopy) are reported in appropriate units flagging any transgression of health-related safety limits. The emissions collected during the nail penetration testing are summarized in tabular and graphic formats. The NMC showed a higher thermal runaway intensity; it was the only chemistry that continued to have thermal propagation after the initial nail penetration and it had marginally higher temperatures recorded. In contrast, the LFP produced the least number of harmful emissions while the LMO recorded the lowest temperatures.