Tuning surface chemistry of TiC electrodes for lithium-air batteriesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 17 января 2017 г.
Аннотация:One of the key problems hindering practical implementation of lithium-air batteries is caused by carbon cathode chemical instability leading to low energy efficiency and short cycle life. Titanium carbide (TiC) nanopowders are considered as an alternative cathode material, however, they are intrinsically reactive towards oxygen and its stability is controlled totally by a surface overlayers. Using photoemission spectroscopy we show that lithium-air battery discharge product – lithium peroxide (Li2O2) – easily oxidize clean TiC surface. At the same time TiC surface, which was treated by molecular oxygen under ambient conditions, shows much better stability in contact with Li2O2 that can be explained by presence of a surface layer containing a significant amount of elemental carbon in addition to oxides and oxycarbides. Nevertheless, such protective coatings produced by room temperature oxidation are not practically useful as one of its components – elemental carbon – is oxidized in presence of lithium-air battery discharge intermediates. These results are of critical importance in understanding of TiC surface chemistry and in design of stable lithium-air battery electrodes. We postulate that dense, uniform, carbon-free titanium dioxide surface layers of 2 – 3 nm thickness on TiC will be a promising solution, and thus further efforts should be taken for developing synthetic protocols enabling preparation of TiO2/TiC core-shell structures.