scholarly journals Defect-induced B4C electrodes for high energy density supercapacitor devices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Özge Balcı ◽  
Merve Buldu ◽  
Ameen Uddin Ammar ◽  
Kamil Kiraz ◽  
Mehmet Somer ◽  
...  
Keyword(s):  
Active Carbon ◽  
High Performance ◽  
Carbon Sources ◽  
High Energy ◽  
High Energy Density ◽  
Synthesis Conditions ◽  
High Energy Ball Mill ◽  
Energy Ball ◽  
G Ratio ◽  
Energy And Power Density

AbstractBoron carbide powders were synthesized by mechanically activated annealing process using anhydrous boron oxide (B2O3) and varying carbon (C) sources such as graphite and activated carbon: The precursors were mechanically activated for different times in a high energy ball mill and reacted in an induction furnace. According to the Raman analyses of the carbon sources, the I(D)/I(G) ratio increased from ~ 0.25 to ~ 0.99, as the carbon material changed from graphite to active carbon, indicating the highly defected and disordered structure of active carbon. Complementary advanced EPR analysis of defect centers in B4C revealed that the intrinsic defects play a major role in the electrochemical performance of the supercapacitor device once they have an electrode component made of bare B4C. Depending on the starting material and synthesis conditions the conductivity, energy, and power density, as well as capacity, can be controlled hence high-performance supercapacitor devices can be produced.

scholarly journals Defect-induced B4C Electrodes for High Energy Density Supercapacitor Devices

2021 ◽  
Author(s):  
Özge Balcı ◽  
Ameen Uddin Ammar ◽  
Merve Buldu ◽  
Kamil Kiraz ◽  
Mehmet Somer ◽  
...  
Keyword(s):  
Active Carbon ◽  
High Performance ◽  
Carbon Sources ◽  
High Energy ◽  
High Energy Density ◽  
Synthesis Conditions ◽  
High Energy Ball Mill ◽  
Energy Ball ◽  
G Ratio ◽  
Energy And Power Density

Abstract Boron carbide powders were synthesized by mechanically activated annealing process using anhydrous boron oxide (B2O3) and varying carbon (C) sources such as graphite and activated carbon: The precursors were mechanically activated for different times in a high energy ball mill and reacted in an induction furnace. According to the Raman analyses of the carbon sources, the I(D)/I(G) ratio increased from ~0.25 to ~0.99, as the carbon material changed from graphite to active carbon, indicating the highly defected and disordered structure of active carbon. Complementary advanced EPR analysis of defect centers in B4C revealed that the intrinsic defects play a major role in the electrochemical performance of the supercapacitor device once they have an electrode component made of bare B4C. Depending on the starting material and synthesis conditions the conductivity, energy, and power density, as well as capacity, can be controlled hence high-performance supercapacitor devices can be produced.

FORMATION MECHANISM AND CHARACTERIZATION OF NANOCRYSTALLINE CU SYNTHESIZED BY MECHANO-CHEMICAL METHOD

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2962-2969
Author(s):  
S. SHEIBANI ◽  
A. ATAIE ◽  
S. HESHMATI-MANESH
Keyword(s):  
Reduction Process ◽  
High Energy ◽  
X Ray Diffraction ◽  
Nano Structure ◽  
Synthesis Conditions ◽  
Jma Model ◽  
Surface Areas ◽  
Transmission Electron ◽  
High Energy Ball Mill ◽  
Energy Ball

Nanocrystalline Cu particles were prepared by mechanochemical reduction of cuprite ( CU 2 O ) with graphite in a high-energy ball mill. In order to gain an understanding into the possible mechanisms, the kinetic of the process was investigated using Johnson-Mehl-Avrami (JMA) model. It can be seen that theoretical calculation agrees well with experimental data. It was found that the most important effect of mechanical activation is the formation of the lattice defects and grain boundaries in addition to activated fresh surface areas during milling, which promote the reduction process. The Cu nanopowder was characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM results showed the nano-structure nature of the product processed under the synthesis conditions; the crystallite size was measured almost 30 nm in the 30 h milled powders.

Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
High Performance ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Low Grade ◽  
Thermal Battery ◽  
Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
High Performance ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Low Grade ◽  
Thermal Battery ◽  
Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

scholarly journals Recent Advances in the Synthesis of Polymer-Grafted Low-K and High-K Nanoparticles for Dielectric and Electronic Applications

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2942
Author(s):  
Bhausaheb V. Tawade ◽  
Ikeoluwa E. Apata ◽  
Nihar Pradhan ◽  
Alamgir Karim ◽  
Dharmaraj Raghavan
Keyword(s):  
Energy Density ◽  
Polymer Nanocomposites ◽  
High Performance ◽  
Breakdown Strength ◽  
Polymer Nanocomposite ◽  
High Energy ◽  
Polymer Chains ◽  
High Energy Density ◽  
Grafted Nanoparticles ◽  
Grafting From

The synthesis of polymer-grafted nanoparticles (PGNPs) or hairy nanoparticles (HNPs) by tethering of polymer chains to the surface of nanoparticles is an important technique to obtain nanostructured hybrid materials that have been widely used in the formulation of advanced polymer nanocomposites. Ceramic-based polymer nanocomposites integrate key attributes of polymer and ceramic nanomaterial to improve the dielectric properties such as breakdown strength, energy density and dielectric loss. This review describes the ”grafting from” and ”grafting to” approaches commonly adopted to graft polymer chains on NPs pertaining to nano-dielectrics. The article also covers various surface initiated controlled radical polymerization techniques, along with templated approaches for grafting of polymer chains onto SiO2, TiO2, BaTiO3, and Al2O3 nanomaterials. As a look towards applications, an outlook on high-performance polymer nanocomposite capacitors for the design of high energy density pulsed power thin-film capacitors is also presented.

A High-Performance Free-Standing Zn Anode for Flexible Zinc-Ion Batteries

Nanoscale ◽  
2021 ◽  
Author(s):  
Chenxi Gao ◽  
Jiawei Wang ◽  
Yuan Huang ◽  
Zixuan Li ◽  
Jiyan Zhang ◽  
...  
Keyword(s):  
Energy Density ◽  
High Performance ◽  
Low Cost ◽  
High Energy ◽  
Zinc Ion ◽  
High Energy Density ◽  
Free Standing ◽  
Energy Device ◽  
Zn Anode ◽  
Significant Attention

Zinc-ion batteries (ZIBs) have attracted significant attention owing to their high safety, high energy density, and low cost. ZIBs have been studied as a potential energy device for portable and...

scholarly journals Fabrication of Hierarchical NiMoO4/NiMoO4 Nanoflowers on Highly Conductive Flexible Nickel Foam Substrate as a Capacitive Electrode Material for Supercapacitors with Enhanced Electrochemical Performance

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1143 ◽  
Author(s):  
Anil Yedluri ◽  
Tarugu Anitha ◽  
Hee-Je Kim
Keyword(s):  
Energy Density ◽  
Electrochemical Performance ◽  
Specific Capacitance ◽  
Electrode Material ◽  
High Performance ◽  
Nickel Foam ◽  
High Specific Capacitance ◽  
High Energy ◽  
High Energy Density ◽  
Charge Discharge

Hierarchical NiMoO4/NiMoO4 nanoflowers were fabricated on highly conductive flexible nickel foam (NF) substrates using a facile hydrothermal method to achieve rapid charge-discharge ability, high energy density, long cycling lifespan, and higher flexibility for high-performance supercapacitor electrode materials. The synthesized composite electrode material, NF/NiMoO4/NiMoO4 with a nanoball-like NF/NiMoO4 structure on a NiMoO4 surface over a NF substrate, formed a three-dimensional interconnected porous network for high-performance electrodes. The novel NF/NiMoO4/NiMoO4 nanoflowers not only enhanced the large surface area and increased the electrochemical activity, but also provided an enhanced rapid ion diffusion path and reduced the charge transfer resistance of the entire electrode effectively. The NF/NiMoO4/NiMoO4 composite exhibited significantly improved supercapacitor performance in terms of a sustained cycling life, high specific capacitance, rapid charge-discharge capability, high energy density, and good rate capability. Electrochemical analysis of the NF/NiMoO4/NiMoO4 nanoflowers fabricated on the NF substrate revealed ultra-high electrochemical performance with a high specific capacitance of 2121 F g−1 at 12 mA g−1 in a 3 M KOH electrolyte and 98.7% capacitance retention after 3000 cycles at 14 mA g−1. This performance was superior to the NF/NiMoO4 nanoball electrode (1672 F g−1 at 12 mA g−1 and capacitance retention 93.4% cycles). Most importantly, the SC (NF/NiMoO4/NiMoO4) device displayed a maximum energy density of 47.13 W h kg−1, which was significantly higher than that of NF/NiMoO4 (37.1 W h kg−1). Overall, the NF/NiMoO4/NiMoO4 composite is a suitable material for supercapacitor applications.

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