ИСТИНА

Li-air batteries are often considered to be the next generation battery technology, as theoretical predictions promise outstandingly high energy density around 1000 Wh/kg1. Such expectations are based on the low weight of active materials: metallic lithium (at the anode) and oxygen (at the cathode). To facilitate charge transfer and to provide space for insoluble reaction product (Li2O2) a conductive porous matrix most commonly made of carbon black is used as a cathode in Li-O2 cell. Optimizing cathode morphology (pore size distribution, specific surface area) for the best cell performance is a subject of many experimental2 and theoretical3 works, however, there is a lack of the data about сathode pore filling by Li2O2 during discharge, because most frequently technique for studying it – SEM2 – says nothing about the distribution of the peroxide in the depth of the electrode. Here, we for the first time propose small-angle neutron scattering (SANS) study of carbon electrodes of Li-air battery cell. By this technique pores of 1 – 100 nm diameter can be monitored. These pores, according to N2 absorption data, contribute most to the specific surface area. Additionally, in contrast to standard methods of pores size distribution evaluation, by tuning the isotopic composition of the electrolyte SANS allow us to study samples wetted by variety of electrolytes of interest thus giving information about electrochemically active surface.