Understanding Surface and Bulk Electronic Structure of Li-ion Battery Cathodes Operated at Extreme Environment

Li-ion and Li metal batteries are widely used for portable devices due to their high gravimetric and volumetric energy densities and cyclability. However, overcharging and extreme discharging of the battery can lead to overheating and thermal runaway, while improper use can lead to fires and explosions. The volatility and flammability of the organic solvents (ethylene carbonate/dimethyl carbonate) used as electrolytes are the major sources of these thermal stability issues. Therefore, an alternative to flammable electrolytes, room temperature ionic liquids (RTILs) electrolyte chemistry is investigated due to its high thermal and electrochemical stability. Here, the fundamental understanding of developing high temperature Liion battery materials is evaluated using electrochemistry and depth-dependent the X-ray spectroscopy techniques.