Increasing Capacitance of Zeolite-Templated Carbons in Electric Double Layer Capacitors

Abstract

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...

Revival of Zeolite‐Templated Nanocarbon Materials: Recent Advances in Energy Storage and Conversion

“…Synthetic methods for zeolite templated nanocarbons (including CDs, CNTs, graphene, porous carbons, etc.) with tunable size, morphology, and functionalization can be generally classified into three main groups: i) CVD, [84,138,139] ii) carbonization, [61,140] in situ pyrolysis of organic templates or loaded organic molecules, and iii) solvothermal/hydrothermal synthesis. [141] As for CVD, gaseous hydrocarbons are employed as carbon source, such as ethylene and acetylene.…”

“…Zeolite-templated nanocarbons possess sufficient electrical conductivity and excellent microporosity, which endow them tremendous potential as electrode materials in supercapacitors. [73,[75][76][77][78][79][84][85][86]89,90,99,100,142,149,[261][262][263][264][265][266][267] Herein, zeolitetemplated nanocarbon-based supercapacitors are summarized from the aspects of EDLCs, pseudocapacitors, and asymmetric supercapacitors.…”

“…storage materials and electrocatalysts: more specifically, high specific surface area is beneficial for gas adsorption [73] and improvement of double layer capacitance; [55,[74][75][76][77][78][79] the zeolite-templated carbon frameworks with high conductivity are also suitable candidates as electrode materials [55,73,74,77,[79][80][81][82][83][84][85][86][87][88][89][90] and promising scaffolds for electrocatalysts; [81,[91][92][93][94][95][96] hierarchically ordered porosity can enhance mass transfer without pore blockage, [78,91,[97][98][99] which has already been employed as the host of active materials in electrode; [83,85,100] plus ultrafine nanostructures anchored on zeolite-templated nanocarbons, enhanced electrocatalytic performance can be implemented by synergic effect of nanocarbons and metal nanostructures. [81,91] The definition of nanocarbons was proposed by Inagaki et al, [101,102] which contemplates not only the control of size but also the control of struct...…”

Zeolite-Templated Carbon as the Cathode for a High Energy Density Dual-Ion Battery

“…45 While the atomic-level structure of FAU-ZTC is disordered, the pore-to-pore regularity (imparted by the zeolite template during synthesis) is very high, and the volumetric density of homogeneous micropores is higher than that of any other predominantly sp 2 -hybridized carbonbased material. Importantly, the three-dimensionally connected structure of ZTC is sufficiently conductive 46 to permit its use as a bare (capacitive-or pseudocapacitive-type) electrode material in electrochemical capacitors [47][48][49][50][51][52][53][54] (supercapacitors) and batteries 55 , even at very high current rates 48 and low temperatures 56 . These traits make ZTC an ideal material for hosting large, polyatomic anionic species via a capacitive storage mechanism on its inner surface.…”

Carbon Nanotube@MnO2@Polypyrrole Composites: Chemical Synthesis, Characterization and Application in Supercapacitors

“…The energy storage is due to the formation of double layer and redox reactions in carbon derivatives and conducting polymer/ metal oxide, respectively. [7][8][9][10][11] Non-Faradaic process dominates in the EDLC response and depends on specific surface area/ porosity of carbonbased materials. [12][13][14] Carbon derivatives (such as carbon nanotubes, reduced graphene oxide -rGO and modified graphene -Claisen Graphene) [15][16][17][18][19] have been considered as potential candidates for EDLC devices.…”