(Invited) The Bright Future for Electrode Materials─Highly Conductive Porous Na-Embedded Carbon Nanowalls for Energy Conversion and Storage

Abstract

Although doping alkali metals into carbon materials was demonstrated to create highly conductive carbon materials in 1991, the dopants were located on the carbon surface and could be easily oxidized, leading to a great loss in conductivity. As an ideal material, alkali metal atoms must be completely surrounded by carbon atoms to form alkali-metal-embedded carbon material. Such a hypothetical material is totally different from widely used intercalation carbon compounds, in which alkali ions are inserted into spaces between graphite layers. However, the alkali-metal-embedded carbon material has not yet been successfully synthesized for 25 years. In this presentation, I will talk about our recent success of synthesizing highly-conductive porous Na-embedded carbon nano-wall materials (with large accessible surface areas) using an original reaction between liquid Na and CO gas. The novel materials solve the critical issue “the contradiction between high electrical conductivity and large accessible surface area” in current electrode materials. Furthermore, the synthesized materials were tested as electrodes for (1) dye-sensitized solar cells (DSSCs), energy devices, leading to high power conversion efficiency up to 11.03% and (2) supercapacitors, resulting in ultrahigh areal capacitance of 1.14 F/cm2 and a wide operating temperature range.