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181.
NiCo2S4 Nanosheets Grown on Nitrogen‐Doped Carbon Foams as an Advanced Electrode for Supercapacitors 下载免费PDF全文
To push the energy density limit of supercapacitors, a new class of electrode materials with favorable architectures is strongly needed. Binary metal sulfides hold great promise as an electrode material for high‐performance energy storage devices because they offer higher electrochemical activity and higher capacity than mono‐metal sulfides. Here, the rational design and fabrication of NiCo2S4 nanosheets supported on nitrogen‐doped carbon foams (NCF) is presented as a novel flexible electrode for supercapacitors. A facile two‐step method is developed for growth of NiCo2S4 nanosheets on NCF with robust adhesion, involving the growth of Ni‐Co precursor and subsequent conversion into NiCo2S4 nanosheets through sulfidation process. Benefiting from the compositional features and 3D electrode architectures, the NiCo2S4/NCF electrode exhibits greatly improved electrochemical performance with ultrahigh capacitance (877 F g?1 at 20 A g?1) and excellent cycling stability. Moreover, a binder‐free asymmetric supercapacitor device is also fabricated by using NiCo2S4/NCF as the positive electrode and ordered mesoporous carbon (OMC)/NCF as the negative electrode; this demonstrates high energy density (≈45.5 Wh kg?1 at 512 W kg?1). 相似文献
182.
Sheng Chen Jingjing Duan Pengju Bian Youhong Tang Rongkun Zheng Shi‐Zhang Qiao 《Liver Transplantation》2015,5(18)
A multifunctional catalyst electrode mimicking external stimuli–responsive property has been prepared by the in situ growth of nitrogen (N)‐doped NiFe double layered hydroxide (N–NiFe LDH) nanolayers on a 3D nickel foam substrate framework. The electrode demonstrates superior performance toward catalyzing oxygen evolution reaction (OER), affording a low overpotential of 0.23 V at the current density of 10 mA cm?2, high Faradaic efficiency of ≈98%, and stable operation for >60 h. Meanwhile, the electrode can dynamically change its color from gray silver to dark black with the OER happening, and the coloration/bleaching processes persist for at least 5000 cycles, rendering it a useful tool to monitor the catalytic process. Mechanism study reveals that the excellent structural properties of electrode such as 3D conductive framework, ultra thickness of N–NiFe LDH nanolayer (≈0.8 nm), and high N‐doping content (≈17.8%) make significant contribution to achieving enhanced catalytic performance, while N–NiFe LDH nanolayer on electrode is the main contributor to the stimuli‐responsive property with the reversible extraction/insertion of electrons from/into N–NiFe LDH leading to the coloration/bleaching processes. Potential application of this electrode has been further demonstrated by integrating it into a Zn–air battery device to identify the charging process during electrochemical cycling. 相似文献
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184.
Recent Progress in Flexible Electrochemical Capacitors: Electrode Materials,Device Configuration,and Functions 下载免费PDF全文
With increasing demand for portable, flexible, and even wearable electronic devices, flexible energy storage systems have received increasing attention as a key component in this emerging field. Among the options, supercapacitors, commonly referred to as ultracapacitors or electrochemical capacitors, are widely recognized as a potential energy storage system due to their high power, fast charge/discharge rate, long cycling life‐time, and low cost. To date, considerable effort has been dedicated to developing high‐performance flexible supercapacitors based on various electrode materials; including carbon nanomaterials (e.g., carbon nanotubes, graphene, porous carbon materials, carbon paper, and textile), conducting polymers (e.g., polyaniline, polypyrrole, polythiophene), and hybrid materials. A brief introduction to the field is provided and the state‐of‐the‐art is reviewed with special emphasis on electrode materials and device configurations. 相似文献
185.
Electrodes: A New Graphdiyne Nanosheet/Pt Nanoparticle‐Based Counter Electrode Material with Enhanced Catalytic Activity for Dye‐Sensitized Solar Cells (Adv. Energy Mater. 12/2015) 下载免费PDF全文
186.
Flexible Solar Cells: Mechanically Recoverable and Highly Efficient Perovskite Solar Cells: Investigation of Intrinsic Flexibility of Organic–Inorganic Perovskite (Adv. Energy Mater. 22/2015) 下载免费PDF全文
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Linghui Yu Shibo Xi Chao Wei Wenyu Zhang Yonghua Du Qingyu Yan Zhichuan Xu 《Liver Transplantation》2015,5(6)
Several crystal forms of FeOOH are recently reported to be highly promising for lithium storage due to their high capacity, low cost, and environmental friendliness. In particular, β‐FeOOH has shown a capacity of ≈1000 mAh g?1, which is comparable to other promising iron‐based anodes, such as Fe2O3 and Fe3O4. However, its storage mechanisms are unclear and the potential for further improvement remains unexplored. Here, it is shown that this material can have a very high reversible capacity of ≈1400 mAh g?1, which is 20%–40% higher than Fe2O3 and Fe3O4. Such a high capacity is delivered from a series of reactions including intercalation and conversion reactions, formation/deformation of solid‐state electrolyte interface layers and interfacial storage. The mechanisms are studied by a combination of electrochemical and X‐ray absorption near edge spectroscopic approaches. Moreover, very long cycling performance, that is, after even more than 3000 cycles the material still has a significant capacity of more than 800 mAh g?1, is obtained by a simple electrode design involving introducing a rigid support into porous electrodes. Such long cycling performance is for the first time achieved for high‐capacity materials based on conversion reactions. 相似文献
190.
Highly Stable Carbon‐Free Ag/Co3O4‐Cathodes for Lithium‐Air Batteries: Electrochemical and Structural Investigations 下载免费PDF全文
Dennis Wittmaier Natalia A. Cañas Indro Biswas Kaspar Andreas Friedrich 《Liver Transplantation》2015,5(19)
Lithium‐air batteries with an aqueous alkaline electrolyte promise a much higher practical energy density and capacity than conventional lithium‐ion batteries. However, high cathode overpotentials are some of the main problems during cycling. In our previous work, a catalyst combination of Ag and Co3O4 is found that reduces overpotential significantly, and is highly active and also long‐term stable. In the present investigations, X‐ray diffraction and X‐ray photoelectron spectroscopy are applied to study the structure and composition of the cathode material during oxygen reduction reaction and oxygen evolution reaction. Changes of the oxidation states during cycling are responsible for an enhanced oxygen evolution reaction current density but also for losses due to a lower electronic conductivity of the electrodes. The presence and formation of a mixed oxidation state for silver oxide (AgIAgIIIO2) at high potentials is identified. In contradiction to literature, time dependent X‐ray diffraction measurements evidence that this phase is not stable under dry conditions and progressively decays to Ag2O. Electrode mappings show a highly homogeneous oxidation of the electrodes during cycling and quantitative analysis of the observed phases is carried out by Rietveld analysis. Long‐term material behavior completes the investigations. 相似文献