Activation of coal tar derived needle coke with K2CO3 into an active carbon of low surface area and its performance as unique electrode of electric double-layer capacitor

Mitani, Satoshi; Lee, Jun Young; Saito, Koji; Yoon, Seong Ho; Korai, Yozo; Mochida, Isao

doi:10.1016/j.carbon.2005.05.047

Cited by 91 publications

(65 citation statements)

References 12 publications

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“…[20][21][22][23][24][25] The first concern is the microscopic structural change evolved in graphitic carbons that may occur in the electrochemical activation process. The second concern is the charge storage mechanism prevailing after electrochemical activation.…”

Section: -16mentioning

confidence: 99%

Electrochemical Activation of Expanded Graphite Electrode for Electrochemical Capacitor

Ka¹,

Oh²

2008

J. Electrochem. Soc.

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An expanded graphite ͑e-MCMB, mesocarbon microbeads͒ having a wider interlayer spacing ͑d 002 = 0.404 nm͒ than that of common graphites is prepared by heat-treatment of an oxidized MCMB. When the e-MCMB electrode, which gives a negligible capacitance due to a small surface area, is polarized over a certain onset potential ͓4.6-4.8 V ͑vs Li/Li + ͒ for positive and 1.3-1.0 V for negative direction͔, it is electrochemically activated to be a high-capacitance positive and negative electrode for electrochemical capacitor. The activation process involves an ion intercalation into the interlayer space to generate ion-accessible sites. The intercalation is evidenced by the presence of a voltage plateau in the charge-discharge profiles, and by the widening of the interlayer distance ͑by in situ X-ray diffraction study͒ and concomitant electrode swelling ͑by electrochemical dilatometry͒ that occur at the same potential region. The electrochemically activated e-MCMB particles carry slitlike pores of ca. 0.45 nm in the mean interlayer distance, into which ions very likely enter either bare or with partial solvent shells with a mixed adsorption/ intercalation charge storage behavior. A full cell fabricated with two e-MCMB electrodes delivers a volume specific capacitance of 30-24 F mL Until now, electric double-layer capacitors ͑EDLCs͒, which deliver a higher rate capability and longer cycle life as compared to the modern secondary batteries, have been used as the energy storage device for memory back-up systems. [1][2][3][4][5][6] Recently, the markets for EDLCs have been extended to the higher power and higher energy systems such as hybrid electric vehicles. Energy density of the present EDLC, however, does not meet the market's need. Hence, to exploit such new applications, it is necessary to develop electrode materials having a higher energy density than the conventional ones.The energy density of EDLC is given by E = 1/2 CV 2 , where C stands for the capacitance per volume or weight, and V the working voltage. An enlargement in either C or V can thus be the way to achieve a high energy density in EDLCs. 3,5,7 One way to increase the cell voltage is the use of nonaqueous electrolytes. Normally, the cell voltage of EDLCs employing aqueous electrolytes is below 1.2 V, which can, however, be enlarged up to 3.0 V by using nonaqueous electrolytes. The other approach to increase the energy density is the employment of high-capacitance electrode materials, which are normally high-surface-area conductive materials as the electric double layer is formed at the electrode/electrolyte interface.

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Section: -16mentioning

confidence: 99%

Electrochemical Activation of Expanded Graphite Electrode for Electrochemical Capacitor

Ka¹,

Oh²

2008

J. Electrochem. Soc.

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“…Recycling this low-cost waste into a promising active material for energy storage could be of great benefit to both the environmental issues and the energy challenges, and help to achieve green and sustainable energy development. Several previous works based on CTP have been devoted to its applications in LIBs and supercapacitors [30][31][32]. Previous works, however, only focused on activated carbon materials, which showed slightly lower capacity than the already commercialized carbon.…”

Section: Introductionmentioning

confidence: 99%

Nanocomposites of silicon and carbon derived from coal tar pitch: Cheap anode materials for lithium-ion batteries with long cycle life and enhanced capacity

Wang

Chou

Kim

et al. 2013

Electrochimica Acta

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Dou, S. Xue. (2013). Nanocomposites of silicon and carbon derived from coal tar pitch: Cheap anode materials for lithium-ion batteries with long cycle life and enhanced capacity. Electrochimica Acta, 93 (March), 213-221.Nanocomposites of silicon and carbon derived from coal tar pitch: Cheap anode materials for lithium-ion batteries with long cycle life and enhanced capacity AbstractFrom energy and environmental consideration, an industrial waste product, coal tar pitch (CTP), is used as the carbon source for Si/AC composite. We exploited a facile sintering method to largely scale up Si/ amorphous carbon nanocomposite. The composites with 20 wt.% silicon with PVdF binder exhibited stable lithium storage ability for prolonged cycling. The composite anode delivered a capacity of 400.3 mAh g−1 with a high capacity retention of 71.3% after 1000 cycles. Various methods are used to investigate the reason for the outstanding cyclability. The results indicate that the silicon nanoparticles are wrapped by amorphous SiOx and AC in Si/AC composite. This uniform structure is very favorable to lithium storage, the SiOx and AC layers can supply sufficient conductivity and strong elasticity to suppress the stress resulting from the reaction of Si with Li during charge/discharge process.

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“…Then, the carbonized fibers are further activated to increase their specific surface area and total pore volume. The activation treatment requires a high temperature of over 1000°C with activation agents such as KOH, Na2CO3, NaOH, K2CO3, H3PO4, ZnCl2, SiO2 or water vapors (Im et al, 2009a, Jiang et al, 2002, Kim et al, 2007, Mitani et al, 2005. The activation mechanism differs from one activation agent to another.…”

Section: Hydrogen Storagementioning

confidence: 99%

Perspective of electrospun nanofibers in energy and environment

Jayaraman¹,

Li²,

Kumar³

et al. 2014

Biofuel Res. J.

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HIGHLIGHTSElectrospinning is a simple, continuous and scalable technique to produce polymer composite and metal oxide nanofibers with high-aspect ratio and controlled morphologies. It possesses the added advantage of synthesizing porous, hollow and core/shell nanofibers with combination of additional polymers, metals and metal oxides for potential applications. This review focusses on the impact and role of electrospun nanofibers in improving the performances of DSSCs, photocatalysis and hydrogen generation & storage. This review summarizes the recent developments of electrospun semiconducting metal oxide/polymer composite nanostructures in energy and environment related applications. Electrospinning technique has the advantage of synthesizing nanostructures with larger surface to volume ratio, higher crystallinity with phase purity and tunable morphologies like nanofibers, nanowires, nanoflowers and nanorods. The electrospun nanostructures have exhibited unique electrical, optical and catalytic properties than the bulk counter parts as well as nanomaterials synthesized through other approaches. These nanostructures have improved diffusion and interaction of molecules, transfer of electrons along the matrix and catalytic properties with further surface modification and functionalization with combination of metals and metal oxides. GRAPHICAL ABSTRACT ARTICLE INFO ABSTRACT

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Activation of coal tar derived needle coke with K2CO3 into an active carbon of low surface area and its performance as unique electrode of electric double-layer capacitor

Cited by 91 publications

References 12 publications

Electrochemical Activation of Expanded Graphite Electrode for Electrochemical Capacitor

Electrochemical Activation of Expanded Graphite Electrode for Electrochemical Capacitor

Nanocomposites of silicon and carbon derived from coal tar pitch: Cheap anode materials for lithium-ion batteries with long cycle life and enhanced capacity

Perspective of electrospun nanofibers in energy and environment

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