scholarly journals Preparation of Hierarchical Porous Carbon Aerogels by Microwave Assisted Sol-Gel Process for Supercapacitors

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 429 ◽  
Author(s):  
Xueqing Cai ◽  
Guiming Tan ◽  
Zhentao Deng ◽  
Jianhong Liu ◽  
Dayong Gui
Keyword(s):  
Low Cost ◽  
Sol Gel ◽  
Rate Capability ◽  
Single Mode ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
Carbon Aerogels ◽  
Koh Activation ◽  
Activation Process ◽  
Hierarchical Porous

Low-cost resorcinol formaldehyde (RF) organic aerogels were prepared by using resorcinol and formaldehyde as precursors, and sodium hydroxide as a catalyst through a single-mode microwave radiation-assisted sol-gel method and ambient temperature drying. Because of the ring focusing and power-max technology, the fabrication procedure of carbon aerogels (CAs) are much easier, faster, and cheaper than traditional methods. The RF aerogels were then pyrolysized at 900 °C, and the KOH activation process was used to further dredge micropores in the carbon aerogels. The CAs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption, and a series of electrochemical tests. The KOH activated carbon aerogels with 3D-nano-network structure exhibited a high specific surface area of 2230 m2 g−1 with appropriate pore volumes of micro-, meso-, and macropores. The specific capacitance of CAs activated by KOH measured in a two-electrode cell was 170 F g−1 at 0.5 A g−1 with excellent rate capability and cycle stability in 6 M KOH electrolyte.

Hierarchical porous biomass activated carbon for hybrid battery capacitors derived from persimmon branches

2020 ◽  
Vol 10 (4) ◽  
pp. 523-530 ◽  
Author(s):  
Jiaxin Peng ◽  
Juan Yu ◽  
Bicheng Meng ◽  
Lejie Wang ◽  
Xingliang Zhang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Carbon Materials ◽  
Rate Capability ◽  
Mesoporous Structure ◽  
Koh Activation ◽  
Biomass Carbon ◽  
Cycle Stability ◽  
Capacity Reservation ◽  
Hierarchical Porous ◽  
Graphite Structure

Activated carbon materials are used in hybrid battery capacitors. They reduce energy density of devices, and can greatly improve the cycle life and power density. Herein, we used fast-growing persimmon branches in Shaanxi as a biomass carbon source. The persimmon branch activated carbon (PB-AC850) material was found to exhibit abundant graded pore structure similar to graphite structure after KOH activation. The macro/mesoporous structure in PB-AC850 facilitated the ions (solvated PF-6 ) transport, resulting in much better rate capability as compared to commercial activated carbon. It was moreover found from preparation of the hybrid battery capacitor that the addition of activated carbon reduced resistance and polarization of the device. LFP+PB-AC850 exhibited excellent cycle stability with high to 93.4% capacity reservation after 500 cycles at 5C.

scholarly journals Nitrogen-Doped Hierarchically Porous Carbons Derived from Polybenzoxazine for Enhanced Supercapacitor Performance

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 131 ◽  
Author(s):  
Yanhui Wang ◽  
Liyan Dong ◽  
Guiping Lai ◽  
Meng Wei ◽  
Xingbi Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Rate Capability ◽  
Total Pore Volume ◽  
High Specific Capacitance ◽  
High Specific Surface Area ◽  
Koh Activation ◽  
Porous Carbons ◽  
Activation Temperature ◽  
Hierarchically Porous ◽  
Nitrogen Doped

Nitrogen-doped hierarchically porous carbons (HPCs), which are synthesized from benzoxazine resins, were successfully prepared following the processes of polymerization, carbonization, and potassium hydroxide (KOH) activation. As the key factor, the KOH activation temperature influences the pore structure and surface functionality, which are crucial for the excellent performance. The HPC-800 material, with the highest activation temperature (800 °C), displays a hierarchical pore structure, a high specific surface area (1812.4 m2·g−1), large total pore volume (0.98 cm3·g−1), high nitrogen content (1.27%), and remarkable electrical conductivity. It has also presented an excellent electrochemical performance of high specific capacitance of 402.4 F·g−1 at 0.1 A·g−1, excellent rate capability of 248.6 F·g−1 at 10 A·g−1, and long-term cycling stability with >99.0% capacitance retention after 500 cycles at 1 A·g−1 in 6 M KOH aqueous solution.

scholarly journals Facile fabrication of hierarchical porous carbon based on extract separated from coal with outstanding electrochemical performance

RSC Advances ◽  
2017 ◽  
Vol 7 (54) ◽  
pp. 33843-33850 ◽  
Author(s):  
Peng Chang ◽  
Zhihong Qin
Keyword(s):  
Electrochemical Performance ◽  
Porous Carbon ◽  
Low Cost ◽  
Koh Activation ◽  
Porous Carbons ◽  
Hierarchical Porous Carbon ◽  
Hierarchical Porous ◽  
Hierarchical Porous Carbons ◽  
Facile Fabrication

Herein, a novel kind of hierarchical porous carbons were directly synthesized from low-cost extracts of coal by coupling nano MgO template with in situ KOH activation strategy.

scholarly journals Comparison of Surface and Structural Properties of Carbonaceous Materials Prepared by Chemical Activation of Tomato Paste Waste: The Effects of Activator Type and Impregnation Ratio

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Nurgul Ozbay ◽  
Adife Seyda Yargic
Keyword(s):  
Activated Carbon ◽  
Activated Carbons ◽  
Low Cost ◽  
Chemical Activation ◽  
Nitrogen Adsorption ◽  
Xrd Analysis ◽  
Point Of Zero Charge ◽  
Activation Process ◽  
X Ray ◽  
Tomato Paste

Activated carbons were prepared by carbonization of tomato paste processing industry waste at 500°C followed by chemical activation with KOH, K2CO3, and HCl in N2 atmosphere at low temperature (500°C). The effects of different activating agents and impregnation ratios (25, 50, and 100 wt.%) on the materials’ characteristics were examined. Precursor, carbonized tomato waste (CTW), and activated carbons were characterized by using ultimate and proximate analysis, thermogravimetric analysis (TG/DTG), Fourier transform-infrared (FT-IR) spectroscopy, X-ray fluorescence (XRF) spectroscopy, point of zero charge measurements (pHPZC), particle size analyzer, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, nitrogen adsorption/desorption isotherms, and X-ray diffraction (XRD) analysis. Activation process improved pore formation and changed activated carbons’ surface characteristics. Activated carbon with the highest surface area (283 m3/g) was prepared by using 50 wt.% KOH as an activator. According to the experimental results, tomato paste waste could be used as an alternative precursor to produce low-cost activated carbon.

Preparation and Characterization of Phloroglucinol-Resorcinol-Formaldehyde Carbon Aerogels

2013 ◽  
Vol 423-426 ◽  
pp. 523-527
Author(s):  
Xuan Liu ◽  
Zhen Fa Liu ◽  
Hao Lin Fu ◽  
Rui He ◽  
Li Hui Zhang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Sol Gel Process ◽  
Solvent Replacement ◽  
Organic Aerogels

Phloroglucinol-resorcinol-formaldehyde organic aerogels (PRF) were prepared using phloroglucinol, resorcinol and formaldehyde in a sol-gel process, solvent replacement and drying at room temperature. The phloroglucinol-resorcinol-formaldehyde carbon aerogels (CPRF) were prepared by charring the PRF at high temperature under the aegis of helium flow. The microstructure of CPRF was characterized by infrared spectroscopy, specific surface area analyzer and scanning electron microscopy. The results showed that the CPRF had continuous network structure and high specific surface area.

Synthesis and Structural Characteristics of Organic Aerogels with Different Content of Lignin

2010 ◽  
Vol 113-116 ◽  
pp. 1837-1840 ◽  
Author(s):  
Feng Chen ◽  
Jian Li
Keyword(s):  
Structural Characteristics ◽  
Cell Structure ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Raw Material ◽  
Spherical Particles ◽  
Carbon Aerogels ◽  
Scanning Electron Micrographs ◽  
Transmission Electron ◽  
Organic Aerogels

Lignin can be used as a cheap raw material to prepare organic and carbon aerogels based upon the sol-gel reactions. Different concent lignin organic aerogels have been prepared by sol–gel polymerization of formaldehyde with resorcinol, following by the process of RF-gel production and subsequent freeze drying. The resulting materials were characterized by FT-IR analysis, nitrogen adsorption, transmission electron microscopy and Scanning electron micrographs. The structural properties organic aerogel depend on the amount of lignin added to the sol-gel system. and the LRF aerogels obtained in the experimental have an open cell structure with continuous porosity and homogeneous spherical particles.

scholarly journals Hierarchical Porous Carbon Derived from Sichuan Pepper for High-Performance Symmetric Supercapacitor with Decent Rate Capability and Cycling Stability

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 553 ◽  
Author(s):  
Hengshuo Zhang ◽  
Wei Xiao ◽  
Wenjie Zhou ◽  
Shanyong Chen ◽  
Yanhua Zhang
Keyword(s):  
Specific Capacitance ◽  
Current Density ◽  
High Performance ◽  
High Current Density ◽  
Rate Capability ◽  
Cycling Stability ◽  
Koh Activation ◽  
High Current ◽  
Symmetric Supercapacitor ◽  
Hierarchical Porous

Hierarchical micro-mesoporous carbon (denoted as HPC-2 in this study) was synthesized by pre-carbonization of biomass Sichuan pepper followed by KOH activation. It possessed well-developed porosity with the specific surface area of 1823.1 m2 g−1 and pore volume of 0.906 cm3 g−1, and exhibited impressive supercapacitive behaviors. For example, the largest specific capacitance of HPC-2 was tested to be ca. 171 F g−1 in a three-electrode setup with outstanding rate capability and stable electrochemical property, whose capacitance retention was near 100% after cycling at rather a high current density of 40 A g−1 for up to 10,000 cycles. Furthermore, a two-electrode symmetric supercapacitor cell of HPC-2//HPC-2 was constructed, which delivered the maximum specific capacitance and energy density of ca. 30 F g−1 and 4.2 Wh kg−1, respectively, had prominent rate performance and cycling stability with negligible capacitance decay after repetitive charge/discharge at a high current density of 10 A g−1 for over 10,000 cycles. Such electrochemical properties of HPC-2 in both three- and two-electrode systems are superior or comparable to those of a great number of porous biomass carbon reported previously, hence making it a promising candidate for the development of high-performance energy storage devices.

N, S, O Self-Doped Porous Carbon Nanoarchitectonics Derived from Pinecone with Outstanding Supercapacitance Performances

2020 ◽  
Vol 20 (5) ◽  
pp. 2728-2735 ◽  
Author(s):  
Di Zhang ◽  
Yanchun Xue ◽  
Jiale Chen ◽  
Xingmei Guo ◽  
Dandan Yang ◽  
...  
Keyword(s):  
Porous Carbon ◽  
Electrode Materials ◽  
Low Cost ◽  
High Specific Capacitance ◽  
High Specific Surface Area ◽  
Koh Activation ◽  
Double Layer Capacitor ◽  
Symmetric Supercapacitor ◽  
Biomass N ◽  
One Step

Biomass-derived porous carbons are considered as one of the most promising electrode materials for supercapacitors due to their low-cost and natural abundance. In this work, pinecone is used to fabricate biomass N, S, O-doped porous carbon via one-step carbonization process with KOH activation. By optimizing the additive amount of KOH and calcination temperature, the asprepared product shows a high specific surface area and pore volume up to 1593.8 m2 g−1 and 0.8582 cm3 g−1, respectively. As an electric double-layer capacitor (EDLC) electrode, the N, S, O-doped porous carbon exhibits a high specific capacitance of 285 F g−1 at 0.5 A g−1 and good rate performance with a capacitance retention of 78.6% from 0.5 to 20 A g−1. Furthermore, the as-assembled symmetric supercapacitor with 6 mol L−1 KOH as electrolyte possesses a promising energy density of 6.34 Wh kg−1 and a power density of 250 W kg−1. Outstanding cycling stability was also demonstrated with 94.4% capacitance retention after 10,000 charge/discharge cycles at 1 A g−1.

Synthesis and Structural Characterization of SiO2-Al2O3 Xerogels

2007 ◽  
Vol 336-338 ◽  
pp. 2286-2289
Author(s):  
Fei He ◽  
Xiao Dong He ◽  
Yao Li
Keyword(s):  
Structural Change ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Mesoporous Structure ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
Molar Ratio

Low-density xSiO2-(1-x)Al2O3 xerogels with x=0.9, 0.8, 0.7, 0.6 (mole fractions) were prepared by sol-gel and non-supercritical drying. Silica alkogels, which were the framework of binary composite materials, formed from tetraethyl orthosilicate (TEOS) by hydrolytic condensation with a molar ratio of TEOS: H2O: alcohol: hydrochloric acid: ammonia =1: 4: 10: 7.5×10-4: 0.0375. Aluminum hydroxide derived from Al(NO3)3·9H2O and NH4OH acting in the alcohol solution under the condition of catalyst. After filtrating and washing, the precipitation was mixed into silica sols to form SiO2-Al2O3 mixed oxide gels with different silicon and aluminum molar ratio. The structural change and crystallization of the binary xerogels were investigated after heat treatment at 600 for 2 h by the means of X-ray diffraction. Nitrogen adsorption experiment was performed to estimate specific surface area, porous volume and pore size distribution. The structural change of xerogels was observed by FT-IR spectroscopy. The resulting mixed xerogels possess of mesoporous structure which is characteristic of cylindrical pores, high specific surface area of 596-863 m2/g and a relatively narrow pore distribution of 2.8-30 nm. Al2O3 is introduced into the SiO2 phase and some of Al-O-Si bonds form.

Mask-painting symmetrical micro-supercapacitors based on scalable, pore size adjustable, N-doped hierarchical porous carbon

2021 ◽  
Author(s):  
Shijin Zhu ◽  
Michael Göbel ◽  
Petr Formanek ◽  
Frank Simon ◽  
Michael Sommer ◽  
...  
Keyword(s):  
Energy Storage ◽  
Rate Capability ◽  
High Specific Surface Area ◽  
High Rate ◽  
Hierarchical Porous Carbon ◽  
High Rate Capability ◽  
Hierarchical Pore Structure ◽  
Hierarchical Porous ◽  
Energy Storage Applications ◽  
Hierarchical Pore

High specific surface area carbons with hierarchical pore structure and outstanding conductivity have gained tremendous attention for energy storage applications due to their stable electrochemical properties and high rate capability....

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