(670f) Mechanistic Evaluation of Thermal Runaway in Potassium-Ion Batteries

Despite widespread commercial use, safety concerns of rechargeable lithium-ion batteries continue due to their susceptibility to thermal runaway. Exothermic reactions between the organic electrolyte, electrode materials, and the anode solid electrolyte interphase (SEI) lead to thermal runaway at higher temperatures (> 80°C), resulting in eventual cell rupturing and combustion. Recent interest in potassium-ion batteries (KIBs) as an inexpensive energy storage technology has arisen due to its natural abundance and compatibility with graphite anodes. The thermal stability of this K-ion graphite system, however, is completely unknown in terms of runaway onset temperature, enthalpy of reactions, and degradation mechanisms. We have explored thermal runaway of graphite and carbon anodes in KIBs through differential scanning analysis (DSC) of charged electrodes to evaluate the practicality of this new system. By selectively studying cell components (e.g. electrolyte, SEI, binder), we identified the sources of exothermic peaks and found that the profile is strongly dependent on the cell preparation and material properties. Interestingly, compared to the Li-ion battery case, less total heat generation occurs from 50-450°C (415 J g^-1 vs. 1170 J g^-1) for a standard graphite anode, and the system overall shows great potential for improved safety by materials engineering.