Yoongon Kim

Bifunctional Hybrid Catalysts with Perovskite LaCo0.8Fe0.2O3 Nanowires and Reduced Graphene Oxide Sheets for an Efficient Li-O2 Battery Cathode

In this paper, bifunctional catalysts consisting of perovskite LaCo0.8Fe0.2O3 nanowires (LCFO NWs) with reduced graphene oxide (rGO) sheets were prepared for use in lithium-oxygen (Li-O2) battery cathodes. The prepared LCFO@rGO composite was explored as a cathode catalyst for Li-O2 batteries, resulting in an outstanding discharge capacity (ca. 7088.2 mAh g-1) at the first cycle. Moreover, a high stability of the O2-cathode with the LCFO@rGO catalyst was achieved over 56 cycles under the capacity limit of 500 mAh g-1 with a rate of 200 mA g-1, as compared to the Ketjenblack carbon and LCFO NWs. The enhanced electrochemical performance suggests that these hybrid composites of perovskite LCFO NWs with rGO nanosheets could be a perspective bifunctional catalyst for the cathode oxygen reduction and oxygen evolution reactions in the development of next-generation Li-O2 battery cathodes.

Ruthenium Oxide Incorporated One-Dimensional Cobalt Oxide Composite Nanowires as Lithium-Oxygen Battery Cathode Catalysts

Ruthenium oxide/cobalt oxide composite nanowires (RuO2/Co3O4 NWs) have been synthesized through a simple and efficient electrospinning method for use as bifunctional electrocatalysts in rechargeable lithium–oxygen (Li–O2) battery cathodes. The as‐prepared NWs have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and X‐ray absorption near‐edge structure (XANES) spectroscopy. The intrinsic activities of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) over the obtained composite NWs are studied using a rotating‐disk electrode technique. The RuO2/Co3O4 NWs exhibit superior bifunctional electrocatalytic activities for both the ORR and the OER if compared to the activities of the Co3O4 NWs and only Ketjenblack (KB). If the RuO2/Co3O4 NWs are employed as cathode catalysts in Li–O2 cells, great improvements in terms of the discharge capacity, coulombic efficiency, and cycle stability with low discharge‐charge overpotentials are achieved. These can be attributed to the high bifunctional catalytic activities of the RuO2/Co3O4 composite NWs.