Premium
Micrometer‐Sized RuO 2 Catalysts Contributing to Formation of Amorphous Na‐Deficient Sodium Peroxide in Na–O 2 Batteries
Author(s) -
Wu Feng,
Xing Yi,
Lai Jingning,
Zhang Xiaoxiao,
Ye Yusheng,
Qian Ji,
Li Li,
Chen Renjie
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201700632
Subject(s) - materials science , micrometer , electrochemistry , catalysis , amorphous solid , cathode , battery (electricity) , chemical engineering , graphite , nanotechnology , oxide , electrode , metallurgy , crystallography , chemistry , organic chemistry , physics , optics , engineering , power (physics) , quantum mechanics
The results obtained herein demonstrate that the oxygen electrode plays a critical role in determining the morphology and chemical composition of discharge products in Na–O 2 batteries. Micrometer‐sized cubic NaO 2 , film‐like NaO 2 , and nano‐sized amorphous spherical Na 2‐ x O 2 are characterized as the main discharge products on the surface of reduced graphite oxide (rGO), boron‐doped rGO (B‐rGO), and micrometer‐sized RuO 2 catalyst‐coated B‐rGO (m‐RuO 2 ‐B‐rGO) cathodes, respectively. The Na–O 2 battery with m‐RuO 2 ‐B‐rGO as the cathode exhibits a much longer cycle life than those with the other cathodes, maintaining an unchanged capacity (0.5 mAh cm ‐2 ) after 100 cycles at a current density of 0.05 mA cm ‐2 . A good rate capability and deep discharge–charge energy efficiency are also obtained. The excellent electrochemical performance of the battery is attributed to the effect of the micrometer‐sized RuO 2 catalyst. Owing to the high affinity of RuO 2 for oxygen, the amorphous phase Na 2‐ x O 2 discharge product, which has good electrical contact with the RuO 2 particles, can decompose completely under 3.1 V without a sudden voltage jump. Meanwhile, the micrometer‐sized RuO 2 catalysts also provide enough active sites and space for the reactions, and effectively minimize the occurrence of side reactions between discharge products and carbon defects.