Invited
SIMULATIONS OF MATERIALS AND PROCESSES FOR Li-Air AND Na-Air BATTERIES

Li-Air and Na-Air batteries show big promise for future electric transportation and are therefore the subject of intense research efforts in both experiment and theory. A major challenge is to produce a battery with the promised energy capacity but also with many cycles of operation and proven safety.

One challenge is to enhance the O₂ availability at the electrode reaction site, this can be accomplished by choosing an appropriate solvent. An approach that was recently shown successful by experiment is to add perfluorinated carbons (PFCs) into the porous electrode, this family of materials is known to have high solubility of O­₂ but has lower solubility for the Li and Na ions. In our Molecular Dynamics (MD) simulations we show how PFCs can mix with triglyme (TEGDME) which is a common ether based solvent for the Li ions. We also calculate the diffusion of oxygen in both solvents and compare to experimental results.

Another challenge is to find which materials can serve as cathode materials. While there are many parameters that affect the choice, an important parameter is the question of how can crystalline phases of Li₂O₂ (or Na₂O₂) can grow on surfaces of different candidate materials. Such questions can be partially answered by geometrical constraints and first principles calculations – I will describe some of the systems we analyze.

Finally, I will review some of the challenges for future simulations.