Radical reactivity evaluation for the identification of electrolyte materials involved in electrode–electrolyte interphase formation

The use of Li metal anodes for secondary batteries is a major challenge in the academe. To address the issues associated with this, there is active research to obtain electrolytes for the effective use of Li metal anodes. Specifically, there is considerable attention on improving the oxidation stability and suppressing the dendrite formations of Li metal through the formation of a passivation film on cathode and anode surfaces. However, there is limited knowledge on the correlation between electrolyte molecules and formation of passivation films at a molecular level, which prevents the efficient development of high-performance electrolytes. In this work, we analyze reported experimental results on materials that contribute to the formation of cathode and anode films in widely used ether-based electrolytes through first-principles calculations. The oxidation and reduction energies are found to be insufficient in examining the influencing materials of the cathode and anode films. In addition, the evaluation of the reactivity of the radicals involved in the oxidation/reduction process is noted to be the most simple and effective method to explain the experimental results in electrolyte materials. Therefore, radical reactivity is important in interpreting experimental phenomena and efficiently determining the desired film-forming materials among a myriad of organic materials.