(Invited) Highly Durable Platelet-Type Carbon Nanofibers for Oer in Alkaline Electrolyte

Abstract

Porous anodic alumina films formed by anodizing of aluminum in acid electrolytes have a highly ordered, nanopore channels, which have attracted increased attention as template for various nanomaterials. Utilizing this template, platelet-type carbon nanofibers (pCNFs) have been successfully prepared by simply heating a mixture of the template and polymer powders, such as polyvinyl chloride and polyvinyl alcohol, in argon atmosphere via liquefied intermediate of the polymers (1, 2). The graphitization degree of pCNFs increases with annealing temperature, and interestingly, the neighboring reactive carbon edge sites at the sidewall of pCNFs form loops of several carbon layers at above 2000ºC. Here, we demonstrate that such pCNFs with high graphitization degree and loop structure exhibit extremely high oxidation resistance under oxygen evolution reaction (OER) conditions in highly alkaline electrolyte for a zinc-air secondary battery application.During galvanostatic OER on the state-of-the-art highly active Ca2FeCoO5 electrode with a conventional carbon black conductive agent in 4 mol dm-3 KOH electrolyte consumed the carbon black almost completely within a few days, whereas that with pCNFs annealed at 2400ºC exhibited almost no consumption of the pCNFs even after one month. The carbon nanofibers with platelet structure and high graphitization degree are promising for the air electrode materials in a zinc-air battery. Acknowledgment This work was supported in part by the RISING2 (Research and Development Initiative for Science Innovation of New Generation Batteries 2) of the New Energy and Industrial Technology Development Organization (NEDO), Japan. 1. H. Konno, S. Sato, H. Habazaki and M. Inagaki, Carbon, 42, 2756 (2004).2. H. Habazaki, M. Kiriu, M. Hayashi and H. Konno, Mater. Chem. Phys., 105, 367 (2007).