Aashutosh Mistry, Purdue University
Thermal Cross-Talk in Lithium-Ion Battery Safety
Written by Hortense Le Ferrand
Lithium batteries typically heat during their use, due to electrochemical operation. If the heat generated is not dissipated properly, the temperature rises to unsafe levels and may trigger an uncontrolled heating of the batteries, usually terminating into degradation.
Aashutosh Mistry and his co-workers are modeling this phenomenon based on microscopic experimental characterization, revealing the correlation between the electrode microstructures and the heat rates generated. Indeed, the electrodes, both anode and cathode, of the battery are composed of a multiple phase microstructure enabling the transport of lithium, with graphite flakes dispersed in polyvinylidiene fluoride (Teflon) for the anode and nickel-manganese-cobalt (NMC) oxide spherical particles in another polymer for the cathode. During operation, heat, mass, and charge transfers occur so that the changes in the porosity and tortuosity in the microstructure at one electrode strongly affect the electronic conductivity of the other.
Their predictions also highlight the difference in thermal response during charging and discharging. A key conclusion of their study is the existence of closely coupled interactions between anode and cathode for electrochemical performance, thermal response, and chemical degradation. This suggests that each of these phenomena cannot be completely studied in an independent isolated test, and a holistic description is necessary.