Instability of a Noncrystalline NaO2 Film in Na-O-2 Batteries: The Controversial Effect of the RuO2 Catalyst

Autor: Hande Ustunel, Eda Yilmaz, Hye Ryung Byon, Mohammad Fathi Tovini, Merve Demirtas, Misun Hong, Daniele Toffoli, Ji-Won Park
Přispěvatelé: Fathi Tovini, Mohammad, Hong, Misun, Park, Jiwon, Demirtaş, Merve, Toffoli, Daniele, Ustunel, Hande, Byon, Hye Ryung, Yllmaz, Eda, Biophysics Photosynthesis/Energy, LaserLaB - Energy, Physics and Astronomy
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Tovini, M F, Hong, M, Park, J, Demirtas, M, Toffoli, D, Ustunel, H, Byon, H R & Yilmaz, E 2018, ' Instability of a Noncrystalline NaO2 Film in Na-O-2 Batteries: The Controversial Effect of the RuO2 Catalyst ', Journal of Physical Chemistry C, vol. 122, no. 34, pp. 19678-19686 . https://doi.org/10.1021/acs.jpcc.8b06024
Journal of Physical Chemistry C
Journal of Physical Chemistry C, 122(34), 19678-19686. American Chemical Society
ISSN: 1932-7447
DOI: 10.1021/acs.jpcc.8b06024
Popis: The unique electrochemical and chemical features of sodium-oxygen (Na-O2) batteries distinguish them from the lithium-oxygen (Li-O2) batteries. NaO2 as the main discharge product is unstable in the cell environment and chemically degrades, which triggers side products' formation and charging potential increment. In this study, RuO2 nanoparticles dispersed on carbon nanotubes (CNTs) are used as the catalyst for Na-O2 batteries to elucidate the effect of the catalyst on these complex electrochemical systems. The RuO2/CNT contributes to the formation of a poorly crystalline and coating-like NaO2 structure during oxygen reduction reaction, which is drastically different from the conventional micron-sized cubic NaO2 crystals deposited on the CNT. Our findings demonstrate a competition between NaO2 and side products' decompositions for RuO2/CNT during oxygen evolution reaction (OER). We believe that this is due to the lower stability of a coating-like NaO2 because of its noncrystalline nature and high electrode/electrolyte contact area. Although RuO2/CNT catalyzes the decomposition of side products at a lower potential (3.66 V) compared to CNT (4.03 V), it cannot actively contribute to the main electrochemical reaction of the cell during OER (NaO2 → Na+ + O2 + e-) because of the fast chemical degradation of the film NaO2 to the side products. Therefore, tuning the morphology and crystallinity of NaO2 by a catalyst is detrimental for the Na-O2 cell performance and it should be taken into account for the future applications. This study is financially supported by The Scientific and Technological Research Council of Turkey (TUBITAK) with the project number 115M375 and the National Research Foundation (NRF) of Korea (grant NRF-2016R1C1B2008690).
Databáze: OpenAIRE