Hierarchical porous carbon derived from sulfonated pitch for electrical double layer capacitors
TL;DR: In this article, Hierarchical porous carbon (HPC) has been synthesized using sulfonated pitch as a precursor with a simple KOH activation process and the effect of the activation agent to precursor ratio on the porosity and the specific surface area is studied by nitrogen adsorption-desorption.
About: This article is published in Journal of Power Sources.The article was published on 2014-04-15. It has received 142 citations till now. The article focuses on the topics: Specific surface area.
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TL;DR: In this article, the effects of the PAN/RL mass ratios varying from 9/1,7/3 to 5/5 and heat-treatment temperatures (HTTs) in the range from 800, 1000 to 1300 °C on morphology and structure of carbon nanofibrous webs (CNFs) are systematically studied.
229 citations
TL;DR: Nitrogen-enriched hierarchically porous carbons (HPCs) were synthesized from a novel nitrile-functionalized benzoxazine based on Benzoxazine chemistry using a soft-templating method and a potassium hydroxide (KOH) chemical activation method and used as electrode materials for supercapacitors.
Abstract: Nitrogen-enriched hierarchically porous carbons (HPCs) were synthesized from a novel nitrile-functionalized benzoxazine based on benzoxazine chemistry using a soft-templating method and a potassium hydroxide (KOH) chemical activation method and used as electrode materials for supercapacitors. The textural and chemical properties could be easily tuned by adding a soft template and changing the activation temperature. The introduction of the soft-templating agent (surfactant F127) resulted in the formation of mesopores, which facilitated fast ionic diffusion and reduced the internal resistance. The micropores of HPCs were extensively developed by KOH activation to provide large electrochemical double-layer capacitance. As the activation temperature increased from 600 to 800 °C, the specific surface area of nitrogen-enriched carbons increased dramatically, micropores were enlarged, and more meso/macropores were developed, but the nitrogen and oxygen content decreased, which affected the electrochemical performance. The sample HPC-800 activated at 800 °C possesses a high specific surface area (1555.4 m(2) g(-1)), high oxygen (10.61 wt %) and nitrogen (3.64 wt %) contents, a hierarchical pore structure, a high graphitization degree, and good electrical conductivity. It shows great pseudocapacitance and the largest specific capacitance of 641.6 F g(-1) at a current density of 1 A g(-1) in a 6 mol L(-1) KOH aqueous electrolyte when measured in a three-electrode system. Furthermore, the HPC-800 electrode exhibits excellent rate capability (443.0 F g(-1) remained at 40 A g(-1)) and good cycling stability (94.3% capacitance retention over 5000 cycles).
181 citations
TL;DR: The studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices.
Abstract: High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm2 at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices.
169 citations
TL;DR: In this article, a nitrogen-doped porous interconnected carbon nanosheets derived from an easily gained and green plant-waste (pomelo mesocarps) by simultaneous activation, carbonization and nitrogen doped processes using CaCl2 as activating agent and urea as nitrogen source.
163 citations
TL;DR: In this paper, the storage mechanism of soft carbon anodes has been investigated and it has been shown that sodium ions intercalate into graphenic layers, leading to an irreversible quasi-plateau at ∼ 0.5 V versus Na+/Na as well as an irreversible expansion seen by in situ transmission electron microscopy and X-ray diffraction.
Abstract: Graphite is the commercial anode for lithium-ion batteries; however, it fails to extend its success to sodium-ion batteries. Recently, we demonstrated that a low-cost amorphous carbon—soft carbon exhibits remarkable rate performance and stable cycling life of Na-ion storage. However, its Na-ion storage mechanism has remained elusive, which has plagued further development of such carbon anodes. Here, we remedy this shortfall by presenting the results from an integrated set of experimental and computational studies that, for the first time, reveal the storage mechanism for soft carbon. We find that sodium ions intercalate into graphenic layers, leading to an irreversible quasi-plateau at ∼0.5 V versus Na+/Na as well as an irreversible expansion seen by in situ transmission electron microscopy (TEM) and X-ray diffraction (XRD). Such a high-potential plateau is correlated to the defective local structure inside the turbostratic stacking of soft carbon and the associated high-binding energies with Na ions, sug...
162 citations
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TL;DR: This work has shown that combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries.
Abstract: Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.
14,213 citations
TL;DR: In this article, different types of capacitors with a pure electrostatic attraction and/or pseudocapacitance effects are presented, and their performance in various electrolytes is studied taking into account the different range of operating voltage (1V for aqueous and 3 V for aprotic solutions).
4,091 citations
TL;DR: The results challenge the long-held axiom that pores smaller than the size of solvated electrolyte ions are incapable of contributing to charge storage.
Abstract: Carbon supercapacitors, which are energy storage devices that use ion adsorption on the surface of highly porous materials to store charge, have numerous advantages over other power-source technologies, but could realize further gains if their electrodes were properly optimized. Studying the effect of the pore size on capacitance could potentially improve performance by maximizing the electrode surface area accessible to electrolyte ions, but until recently, no studies had addressed the lower size limit of accessible pores. Using carbide-derived carbon, we generated pores with average sizes from 0.6 to 2.25 nanometer and studied double-layer capacitance in an organic electrolyte. The results challenge the long-held axiom that pores smaller than the size of solvated electrolyte ions are incapable of contributing to charge storage.
3,348 citations
TL;DR: In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-Capacitance have been explored and show not only enhanced capacitance, but as well good cyclability.
Abstract: Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.
2,497 citations
TL;DR: Porous carbon was synthesized by heating the precursor FA within the pores of MOF-5 to display a high specific surface area and important hydrogen uptake and excellent electrochemical properties as an electrode material for electrochemical double-layered capacitor (EDLC).
Abstract: Porous carbon was synthesized by heating the precursor FA within the pores of MOF-5. The resultant carbon displayed a high specific surface area (BET, 2872 m2·g−1) and important hydrogen uptake (2.6 wt % at 760 Torr, −196 °C) as well as excellent electrochemical properties as an electrode material for electrochemical double-layered capacitor (EDLC).
1,538 citations