SnO2 model electrode cycled in Li-ion battery reveals the formation of Li2SnO3 and Li8SnO6 phases through conversion reactions / Giulio Ferraresi, Claire Villevieille, Izabela Czekaj, Michael Horisberger, ... więcej

SnO2 model electrode cycled in Li-ion battery reveals the formation of Li2SnO3 and Li8SnO6 phases through conversion reactions / Giulio Ferraresi, Claire Villevieille, Izabela Czekaj, Michael Horisberger, Petr Novák, Mario El Kazzi // ACS Applied Materials & Interfaces [Dokument elektroniczny]. – 2018, Vol. 10, Iss. 10, s. 8712-8720 : rys., schem., tab., wykr. – Tryb dostępu: https://pubs.acs.org/doi/pdf/10.1021/acsami.7b19481. – Bibliogr. 30 poz., Abstr. – Data udostępnienia online: 2018-02-14. – doi: 10.1021/acsami.7b19481. – ISSN 1944-8244

SnO2 is an attractive negative electrode for Li-ion battery thanks to its high specific charge capacity compared to the commercial graphite. However, the various conversion and alloy reactions taking place ... więcej

SnO2 is an attractive negative electrode for Li-ion battery thanks to its high specific charge capacity compared to the commercial graphite. However, the various conversion and alloy reactions taking place during lithiation/delithiation, as well as, the electrolyte stability remain not fully elucidated and governed by plenty of ambiguities. To shed light on these different processes, amorphous thin film of SnO2 as model electrode is investigated by combining post-mortem X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) supported by density functional theory (DFT) calculations. The potential dependency during the early stages of cycling on the surface evolution revealed during lithiation the presence of multiple overlapped reversible reactions leading to the formation of Li2SnO3 and Sn0 phases between 2 V and 0.8 V vs. Li+/Li. While between 0.45 V and 5 mV Li8SnO6, Li2O and LixSn phases are formed. The electrolyte reduction is also observed to happen in two steps, at 1.4 V and 1 V leading to the decomposition of the LiPF6 and EC/DMC respectively. During delithiation up to 1.5 V, reversible reactions occur resulting with the appearance back of Sn0 and the oxidation of Li2O. Above 1.5 V the partial oxidation of the Sn0 to SnOx take place without having a clear evidence of the oxygen source. The later finding tends to limit the conversion reaction in favour of reversible alloy reaction as demonstrated by the long-term cycling simples.