Data on high performance supercapacitors based on mesoporous activated carbon materials with ultrahigh mesopore volume and effective specific surface area.
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ABSTRACT:
SUBMITTER: Lu Y
PROVIDER: S-EPMC5997976 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The recycling of macromolecular biowastes has been a problem for the agriculture industry. In this study, a novel N, S-codoped activated carbon material with an ultrahigh specific area was produced for the application of a supercapacitor electrode, using tobacco stalk biowastes as the carbon source, KOH as the activating agents and thiourea as the doping agent. Tobacco stalk is mainly composed of cellulose, but also contains many small molecules and inorganic salts. KOH activation resulted in many mesopores, giving the tobacco stem-activated carbon a large specific surface area and double-layer capacitance. The specific surface area of the samples reached up to 3733 m2·g-1, while the maximum specific capacitance of the samples obtained was up to 281.3 F·g-1 in the 3-electrode tests (1 A·g-1). The doping of N and S elements raised the specific capacitance significantly, which could be increased to a value as high as 422.5 F·g-1 at a current density of 1 A·g-1 in the 3-electrode tests, but N, S-codoping also led to instability. The results of this article prove that tobacco stalks could be efficiently reused in the field of supercapacitors.
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Project description:All-solid-state high-performance asymmetric supercapacitors (ASCs) are fabricated using ?-MnS as positive electrode and porous eggplant derived activated carbon (EDAC) as negative electrode with saturated potassium hydroxide agar gel as the solid electrolyte. The laminar wurtzite nanostructure of ?-MnS facilitates the insertion of hydroxyl ions into the interlayer space, and the manganese sulfide nanowire offers electronic transportation channels. The size-uniform porous nanostructure of EDAC provides a continuous electron pathway as well as facilitates short ionic transportation pathways. Due to these special nanostructures of both the MnS and the EDAC, they exhibited a specific capacitance of 573.9 and 396 F g(-1) at 0.5 A g(-1), respectively. The optimized MnS//EDAC asymmetric supercapacitor shows a superior performance with specific capacitance of 110.4 F g(-1) and 89.87% capacitance retention after 5000 cycles, a high energy density of 37.6 Wh kg(-1) at a power density of 181.2 W kg(-1) and remains 24.9 Wh kg(-1) even at 5976 W kg(-1). Impressively, such two assembled all-solid-state cells in series can light up a red LED indicator for 15 minutes after fully charged. These impressive results make these pollution-free materials promising for practical applications in solid aqueous electrolyte-based ASCs.
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Project description:Conducting polymers and carbon-based materials such as graphene oxide (GO) and activated carbon (AC) are the most promising capacitive materials, though both offer charge storage through different mechanisms. However, their combination can lead to some unusual results, offering improvement in certain properties in comparison with the individual materials. Cycling stability of supercapacitors devices is often a matter of concern, and extensive research is underway to improve this phenomena of supercapacitive devices. Herein, a high-performance asymmetric supercapacitor device was fabricated using graphene oxide-polyaniline (GO@PANI) nanocomposite as positive electrode and activated carbon (AC) as negative electrode. The device showed 142 F g-1 specific capacitance at 1 A g-1 current density with capacitance retention of 73.94% at higher current density (10 A g-1). Most importantly, the device exhibited very high electrochemical cycling stability. It retained 118.6% specific capacitance of the starting value after 10,000 cycles at 3 Ag-1 and with coulombic efficiency of 98.06 %, indicating great potential for practical applications. Very small solution resistance (Rs, 0.640 ?) and charge transfer resistance (Rct, 0.200 ?) were observed hinting efficient charge transfer and fast ion diffusion. Due to asymmetric combination, potential window was extended to 1.2 V in aqueous electrolyte, as a result higher energy density (28.5 Wh kg-1) and power density of 2503 W kg-1 were achieved at the current density 1 Ag-1. It also showed an aerial capacitance of 57 mF cm-2 at current 3.2 mA cm-2. At this current density, its energy density was maximum (0.92 mWh cm-2) with power density (10.47 W cm-2).
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Project description:A poly(amino acid)-based approach for scalable synthesis of micro-/mesoporous carbon (PC) with high specific surface area and narrow distribution of micro- and mesopores is presented. Using cross-linked poly aspartic acid as a precursor, PC was obtained by in situ one-step carbonization without the activating agent. The resulting PC had an ultrahigh adsorption capacity for H2 (4.43 wt %) and CH4 (4.49 mmol g-1). This novel method could significantly decrease the wastewater hazards caused by washout of the considerable amount of the activating agent. The PC showed promising application in gas adsorption and storage.
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Project description:Supercapacitors store energy either by ion adsorption or fast surface redox reactions. The capacitance produced by the former is known as electrochemical double layer capacitance and the latter is known as pseudo-capacitance. Carbon materials are found to be attractive materials for energy storage, due to their various micro-structures and wide source of availability. Polybenzoxazine (Pbz) is used as a source to produce carbon materials, due to the fact that the obtained carbon will be rich in N and O species for enhanced performance. Moreover, the carbon materials were produced via template-free method. In general, activation temperature plays a main role in altering the porosity of the carbon materials. The main purpose of this study is to find the suitable activation temperature necessary to produce porous carbons with enhanced performance. Considering these points, Pbz is used as a precursor to produce nitrogen-doped porous carbons (NRPCs) without using any template. Three different activation temperatures, namely 700, 800 and 900 °C, are chosen to prepare activated porous carbons; NRPC-700, NRPC-800 and NRPC-900. Hierarchical micro-/ meso-/macropores were developed in the porous carbons with respect to different activation temperatures. PBz source is used to produce carbons containing heteroatoms and an activation process is used to produce carbons with desirable pore structures. The surface morphology, pore structure and binding of heteroatoms to the carbon surface were analyzed in detail. NRPCs produced in this way can be used as supercapacitors. Further, electrodes were developed using these NRPCs and their electrochemical performance including capacitance, specific capacitance, galvanic charge/discharge, impedance, rate capability are analyzed. The obtained results showed that the activation temperature of 900 °C, is suitable to produce NRPC with a specific capacitance of 245 F g-1 at a current density of 0.5 A g-1, that are attributed to high surface area, suitable pore structure and presence of heteroatoms.
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