ИСТИНА

Li-air (Li-O2) batteries attracts lots of attention during the past few years as it hypothetically can provide several times higher specific energy than that of Li-ion batteries. Unfortunately, the cell capacity values achieved in experiments are way below the expectations due to passivation of electrode surface by the discharge product itself, i.e. Li2O2. There are two possible ways of Li2O2 precipitation. Relatively large micron-size Li2O2 particles which do not consume much of the electrode surface are formed as a result of chemical disproportionation reaction (of LiO2 intermediate) in bulk electrolyte. Alternatively, a thin Li2O2 film grows due to electrochemical reduction of LiO2 at the surface [1] with consumption of extra Li+ ions. The previous study [2] predicted high concentration Li+ ions forming electric double layer (EDL), inside a 10 Å thick layer, where high electron transfer (ET) probability enables electrochemical reactions. Excluding lithium ions from the interface should inhibit the Li2O2 formation at the surface. The idea underlying the current work is that supporting organic cations added to electrolyte could replace Li+ ions at the interface. Particularly, cations with highly polar fragments may better fit into electric potential profile inside the EDL. A set of organic cation with different topology and partial atomic charge distributions are tested within MD simulations. Some cations, (e.g. CF3NH3+), are indeed effectively push lithium ions out of the electrochemical reaction zone (see the fig. 1). The generalized recommendation for the choice of supporting cations elicited from the simulation results are provided.