Authors: I Tallo T Thomberg H Kurig A Jänes K Kontturi E Lust
Publish Date: 2012/09/01
Volume: 17, Issue: 1, Pages: 19-28
Abstract
Micro and mesoporous carbidederived carbons CDCs were synthesised from TiC powder via a gasphase reaction using HCl and Cl2 within the temperature range of 700–1100 °C Analysis of Xray diffraction results show that TiCCDCs consist mainly of graphitic crystallites The firstorder Raman spectra showed the graphitelike absorption peaks at ~1577 cm−1 and the disorderinduced peaks at ~1338 cm−1 The lowtemperature N2 sorption experiments were performed and specific surface areas up to 1214 and 1544 m2 g−1 were obtained for TiCCDC HCl synthesised at T = 800 °C and TiCCDC Cl2 synthesised at T = 900 °C respectively For the TiCCDC powders synthesised a bimodal pore size distribution has been established with the first maximum in the region up to 15 nm and the second maximum from 2 to 4 nm The energyrelated properties of supercapacitors based on 1 M C2H53CH3NBF4 in acetonitrile and TiCCDC Cl2 and TiCCDC HCl as electrode materials were also investigated by cyclic voltammetry impedance spectroscopy galvanostatic charge/discharge and constant power methods The specific energy calculated at U = 30 V are maximal for TiCCDC Cl2 800 °C and TiCCDC HCl 900 °C which are 431 and 311 W h kg−1 respectively The specific power calculated at cell potential U = 30 V are maximal for TiCCDC Cl2 1000 °C and TiCCDC HCl 1000 °C which are 8052 and 8475 kW kg−1 respectively The Ragone plots for CDCs prepared by using Cl2 or HCl are quite similar and at high power loads the TiCCDC material synthesised using Cl2 at 900 °C ie the material with optimal pore structure delivers the highest power at constant energyThis work was supported in part by the Estonian Ministry of Education and Research project SF0180002s08 by the Estonian Centre of Excellence in Science High Technology Materials for Sustainable Development by the graduate school “Functional Materials and Technologies” receiving funding from the European Social Fund under project 120401090079 in Estonia and by the Estonian Science Foundation under project no 8172 Prof K Kirsimäe from the Institute of Ecology and Geography and Dr I Sildos from the Institute of Physics at the University of Tartu are thanked for the help with the XRD and Raman studies of carbon samples respectively
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