Enhancement of the specific capacitance in electrochemical double layer capacitors (EDLCs) is of high interest due to the ever increasing demand for high power density energy storage devices. Zeolite templated carbon (ZTC) is a promising EDLC electrode material with large specific surface area and straight, ordered well-defined micropores. In this study, ZTC samples were synthesized using a low pressure chemical vapor deposition (LP CVD) of carbon on sacrificial zeolite Y powder using acetylene gas as a precursor. We demonstrate for the first time how various post-treatments of the produced samples can affect the ZTC microstructure and porosity and how such modifications may significantly improve electrochemical performance characteristics of the ZTC-based EDLC electrodes. The effects of CO 2 activation, ball milling and high temperature annealing process were systematically studied. The best performing samples achieved very large capacitance of over 240 Fg −1 at 1 mVs −1 in 1 M solution of tetraethylammonium tetrafluoroborate in acetonitrile and stable performance in symmetric EDLC devices with no noticeable degradation for over 20,000 cycles at a very high current density of 20 Ag Electrochemical double layer capacitors (EDLCs), also called supercapacitors and ultra-capacitors, have attracted extensive attention as EDLCs can provide high power delivery or update, high cycle efficiency, thermal stability, practically unlimited cycle life and relatively low cost of manufacturing.1 Furthermore, a wide operational temperature range and a relatively easy determination of the state of charge can be considered as additional advantageous aspects.1 Hence, there is an increasing growth in demand for EDLCs in industrial equipments, electronic devices, transportation market, and automotive applications.1-5 Yet, significantly smaller energy density (ca. 5 Wh kg −1 ) compared to the state of art rechargeable Li ion batteries (ca. 180 Wh kg −1 ) urgently calls for improvement in capacitance of EDLCs. 6,7 In addition, for some applications it is crucial to further increase the charge-discharge rate capability without deteriorating energy density characteristics.
1The value of the double layer capacitance formed at the electrode/ electrolyte interface (which directly impacts the energy density of EDLCs) is believed to depend on multiple factors, such as specific surface area (SSA) of the electrically conductive porous carbon electrodes, 1,8-11 pore size distribution (PSD) of the carbon electrodes (which may affect both the pore access by electrolyte ions and the solvation shell distortion and the resulting pore wall -ion separation distance), 1,3,9,12 electron density of states in carbon (which may affect the capacitance of the electrode side of the double layer), 13 electrolyte-carbon interfacial energy (which may affect electrolyte wetting in both large and sub-nm sized pores), 14,15 electrolyte-carbon interactions (which may impact electron density of states in carbon), 16 the presence of doping species within carbon (which...