scholarly journals Highly packed graphene–CNT films as electrodes for aqueous supercapacitors with high volumetric performance

2018 ◽  
Vol 6 (8) ◽  
pp. 3667-3673 ◽  
Author(s):  
Noel Díez ◽  
Cristina Botas ◽  
Roman Mysyk ◽  
Eider Goikolea ◽  
Teófilo Rojo ◽  
...  
Keyword(s):  
Energy Density ◽  
High Density ◽  
High Mass

Aqueous supercapacitors with high volumetric energy density are prepared using high mass, high density (1.5 g cm−3) electrodes of graphene–CNT composites.

scholarly journals A processing diagram for high-density Ti-6Al-4V by selective laser melting

2018 ◽  
Vol 24 (9) ◽  
pp. 1469-1478 ◽  
Author(s):  
Yinmin (Morris) Wang ◽  
Chandrika Kamath ◽  
Thomas Voisin ◽  
Zan Li
Keyword(s):  
Mechanical Properties ◽  
Energy Density ◽  
Processing Parameters ◽  
High Density ◽  
Low Density ◽  
Laser Powder Bed Fusion ◽  
Content Type ◽  
Powder Bed ◽  
Melt Pool ◽  
Hatch Spacing

Purpose Density optimization is the first critical step in building additively manufactured parts with high-quality and good mechanical properties. The authors developed an approach that combines simulations and experiments to identify processing parameters for high-density Ti-6Al-4V using the laser powder-bed-fusion technique. A processing diagram based on the normalized energy density concept is constructed, illustrating an optimized processing window for high- or low-density samples. Excellent mechanical properties are obtained for Ti-6Al-4V samples built from the optimized window. Design/methodology/approach The authors use simple, but approximate, simulations and selective experiments to design parameters for a limited set of single track experiments. The resulting melt-pool characteristics are then used to identify processing parameters for high-density pillars. A processing diagram is built and excellent mechanical properties are achieved in samples built from this window. Findings The authors find that the laser linear input energy has a much stronger effect on the melt-pool depth than the melt-pool width. A processing diagram based on normalized energy density and normalized hatch spacing was constructed, qualitatively indicating that high-density samples are produced in a region when 1 < E* < 2. The onset of void formation and low-density samples occur as E* moves beyond a value of 2. The as-built SLM Ti-6Al-4V shows excellent mechanical performance. Originality/value A combined approach of computer simulations and selected experiments is applied to optimize the density of Ti-6Al-4V, via laser powder-bed-fusion (L-PBF) technique. A series of high-density samples are achieved. Some special issues are identified for L-PBF processes of Ti-6Al-4V, including the powder particle sticking and part swelling issues. A processing diagram is constructed for Ti-6Al-4V, based on the normalized energy density and normalized hatch spacing concept. The diagram illustrates windows with high- and low-density samples. Good mechanical properties are achieved during tensile tests of near fully dense Ti-6Al-4V samples. These good properties are attributed to the success of density optimization processes.

scholarly journals Atomic Modulation of 3D Conductive Frameworks Boost Performance of MnO2 for Coaxial Fiber-Shaped Supercapacitors

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiaona Wang ◽  
Zhenyu Zhou ◽  
Zhijian Sun ◽  
Jinho Hah ◽  
Yagang Yao ◽  
...  
Keyword(s):  
Energy Density ◽  
Specific Capacitance ◽  
High Performance ◽  
High Specific Capacitance ◽  
Superior Performance ◽  
High Mass ◽  
Mass Loading ◽  
Energy Storage Devices ◽  
Free Standing ◽  
Cell Potential

Abstract Coaxial fiber-shaped supercapacitors are a promising class of energy storage devices requiring high performance for flexible and miniature electronic devices. Yet, they are still struggling from inferior energy density, which comes from the limited choices in materials and structure used. Here, Zn-doped CuO nanowires were designed as 3D framework for aligned distributing high mass loading of MnO2 nanosheets. Zn could be introduced into the CuO crystal lattice to tune the covalency character and thus improve charge transport. The Zn–CuO@MnO2 as positive electrode obtained superior performance without sacrificing its areal and gravimetric capacitances with the increasing of mass loading of MnO2 due to 3D Zn–CuO framework enabling efficient electron transport. A novel category of free-standing asymmetric coaxial fiber-shaped supercapacitor based on Zn0.11CuO@MnO2 core electrode possesses superior specific capacitance and enhanced cell potential window. This asymmetric coaxial structure provides superior performance including higher capacity and better stability under deformation because of sufficient contact between the electrodes and electrolyte. Based on these advantages, the as-prepared asymmetric coaxial fiber-shaped supercapacitor exhibits a high specific capacitance of 296.6 mF cm−2 and energy density of 133.47 μWh cm−2. In addition, its capacitance retention reaches 76.57% after bending 10,000 times, which demonstrates as-prepared device’s excellent flexibility and long-term cycling stability.

scholarly journals Hierarchical Carbon Microtube@Nanotube Core–Shell Structure for High-Performance Oxygen Electrocatalysis and Zn–Air Battery

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenfu Xie ◽  
Jianming Li ◽  
Yuke Song ◽  
Shijin Li ◽  
Jianbo Li ◽  
...  
Keyword(s):  
Energy Density ◽  
Power Density ◽  
High Power ◽  
High Performance ◽  
Rational Design ◽  
Specific Capacity ◽  
High Mass ◽  
Core Shell ◽  
High Power Density ◽  
Mass Loading

AbstractZinc–air batteries (ZABs) hold tremendous promise for clean and efficient energy storage with the merits of high theoretical energy density and environmental friendliness. However, the performance of practical ZABs is still unsatisfactory because of the inevitably decreased activity of electrocatalysts when assembly into a thick electrode with high mass loading. Herein, we report a hierarchical electrocatalyst based on carbon microtube@nanotube core–shell nanostructure (CMT@CNT), which demonstrates superior electrocatalytic activity for oxygen reduction reaction and oxygen evolution reaction with a small potential gap of 0.678 V. Remarkably, when being employed as air–cathode in ZAB, the CMT@CNT presents an excellent performance with a high power density (160.6 mW cm−2), specific capacity (781.7 mAhg Zn −1 ) as well as long cycle stability (117 h, 351 cycles). Moreover, the ZAB performance of CMT@CNT is maintained well even under high mass loading (3 mg cm−2, three times as much as traditional usage), which could afford high power density and energy density for advanced electronic equipment. We believe that this work is promising for the rational design of hierarchical structured electrocatalysts for advanced metal-air batteries.

scholarly journals The Ultrafast Laser Ablation of Li(Ni0.6Mn0.2Co0.2)O2 Electrodes with High Mass Loading

2019 ◽  
Vol 9 (19) ◽  
pp. 4067 ◽  
Author(s):  
Penghui Zhu ◽  
Hans Jürgen Seifert ◽  
Wilhelm Pfleging
Keyword(s):  
Energy Density ◽  
Lithium Ion Batteries ◽  
Thick Film ◽  
Power Density ◽  
Discharge Capacity ◽  
Rate Capability ◽  
Lithium Ion ◽  
Ultrafast Laser ◽  
High Mass ◽  
Simultaneous Increase

Lithium-ion batteries have become the most promising energy storage devices in recent years. However, the simultaneous increase of energy density and power density is still a huge challenge. Ultrafast laser structuring of electrodes is feasible to increase power density of lithium-ion batteries by improving the lithium-ion diffusion kinetics. The influences of laser processing pattern and film thickness on the rate capability and energy density were investigated using Li(Ni0.6Mn0.2Co0.2)O2 (NMC 622) as cathode material. NMC 622 electrodes with thicknesses from 91 µm to 250 µm were prepared, while line patterns with pitch distances varying from 200 µm to 600 µm were applied. The NMC 622 cathodes were assembled opposing lithium using coin cell design. Cells with structured, 91 µm thick film cathodes showed lesser capacity losses with C-rates 3C compared to cells with unstructured cathode. Cells with 250 µm thick film cathode showed higher discharge capacity with low C-rates of up to C/5, and the structured cathodes showed higher discharge capacity, with C-rates of up to 1C. However, the discharge capacity deteriorated with higher C-rate. An appropriate choice of laser generated patterns and electrode thickness depends on the requested battery application scenario; i.e., charge/discharge rate and specific/volumetric energy density.

scholarly journals Enhanced Roles of Carbon Architectures in High-Performance Lithium-Ion Batteries

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Lu Wang ◽  
Junwei Han ◽  
Debin Kong ◽  
Ying Tao ◽  
Quan-Hong Yang
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Electrochemical Performance ◽  
Lithium Ion Batteries ◽  
High Performance ◽  
High Capacity ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Density ◽  
High Mass

Abstract Lithium-ion batteries (LIBs), which are high-energy-density and low-safety-risk secondary batteries, are underpinned to the rise in electrochemical energy storage devices that satisfy the urgent demands of the global energy storage market. With the aim of achieving high energy density and fast-charging performance, the exploitation of simple and low-cost approaches for the production of high capacity, high density, high mass loading, and kinetically ion-accessible electrodes that maximize charge storage and transport in LIBs, is a critical need. Toward the construction of high-performance electrodes, carbons are promisingly used in the enhanced roles of active materials, electrochemical reaction frameworks for high-capacity noncarbons, and lightweight current collectors. Here, we review recent advances in the carbon engineering of electrodes for excellent electrochemical performance and structural stability, which is enabled by assembled carbon architectures that guarantee sufficient charge delivery and volume fluctuation buffering inside the electrode during cycling. Some specific feasible assembly methods, synergism between structural design components of carbon assemblies, and electrochemical performance enhancement are highlighted. The precise design of carbon cages by the assembly of graphene units is potentially useful for the controlled preparation of high-capacity carbon-caged noncarbon anodes with volumetric capacities over 2100 mAh cm−3. Finally, insights are given on the prospects and challenges for designing carbon architectures for practical LIBs that simultaneously provide high energy densities (both gravimetric and volumetric) and high rate performance.

scholarly journals Fragmentation and dynamics in Massive Dense Cores in Cygnus-X

2010 ◽  
Vol 6 (S270) ◽  
pp. 53-56 ◽  
Author(s):  
T. Csengeri ◽  
S. Bontemps ◽  
N. Schneider ◽  
F. Motte
Keyword(s):  
Angular Resolution ◽  
High Density ◽  
High Mass ◽  
High Angular Resolution ◽  
Low Mass Stars ◽  
Dense Cores ◽  
Evolutionary Scenario ◽  
Low Mass ◽  
Molecular Tracers ◽  
Resolution Study

AbstractA systematic, high angular-resolution study of IR-quiet Massive Dense Cores (MDCs) of Cygnus-X in continuum and high-density molecular tracers is presented. The results are compared with the quasi-static and the dynamical evolutionary scenario. We find that the fragmentation properties are not compatible with the quasi-static, monolithic collapse scenario, nor are they entirely compatible with the formation of a cluster of mostly low-mass stars. The kinematics of MDCs shows individual velocity components appearing as coherent flows, which indicate important dynamical processes at the scale of the mass reservoir around high-mass protostars.

scholarly journals High‐Density Lignin‐Derived Carbon Nanofiber Supercapacitors with Enhanced Volumetric Energy Density (Adv. Sci. 17/2021)

2021 ◽  
Vol 8 (17) ◽  
pp. 2170109
Author(s):  
Servann Hérou ◽  
Josh J Bailey ◽  
Matt Kok ◽  
Philipp Schlee ◽  
Rhodri Jervis ◽  
...  
Keyword(s):  
Energy Density ◽  
Carbon Nanofiber ◽  
High Density

A new route to tailor high mass loading all-solid-state supercapacitor with ultra-high volumetric energy density

Carbon ◽  
2018 ◽  
Vol 136 ◽  
pp. 46-53 ◽  
Author(s):  
Zhongqian Song ◽  
Weiyan Li ◽  
Yu Bao ◽  
Zhonghui Sun ◽  
Lifang Gao ◽  
...  
Keyword(s):  
Solid State ◽  
Energy Density ◽  
High Mass ◽  
Mass Loading

Electrochemically Reduced Ultra-high Mass Loading Three-Dimensional Carbon Nanofiber Network: A Reproducible and Stable Cell Voltage of 2.0 V and High Energy Density Symmetric Supercapacitor

Nanoscale ◽  
2021 ◽  
Author(s):  
Gunendra Prasad Ojha ◽  
Bishweshwar Pant ◽  
Jiwan Acharya ◽  
Mira Park
Keyword(s):  
Energy Density ◽  
Carbon Nanofiber ◽  
Three Dimensional ◽  
Cell Voltage ◽  
High Energy ◽  
Low Energy ◽  
High Energy Density ◽  
High Mass ◽  
Mass Loading ◽  
Symmetric Supercapacitor

Commercial supercapacitors need high mass loading of more than 10 mg cm-2 and a high working potential window to resolve the low energy density concern. Herein, we have demonstrated a...

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