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61.
Prasannan Karthika Dr. Natarajan Rajalakshmi Dr. Kaveripatnam S. Dhathathreyan 《Chemphyschem》2013,14(16):3822-3826
A low-cost polyester cellulose paper has been used as a substrate for a flexible supercapacitor device that contains aqueous carbon nanotube ink as the electrodes and a polyvinyl alcohol (PVA)-based gel as the electrolyte. Gel electrolytes have attracted much interest due to their solvent-holding capacity and good film-forming capability. The electrodes are characterized for their conductivity and morphology. Because of its high conductivity, the conductive paper is studied in supercapacitor applications as active electrodes and as separators after coating with polyvinylidene fluoride. Carbon nanotubes deposited on porous paper are more accessible to ions in the electrolyte than those on flat substrates, which results in higher power density. A simple fabrication process is achieved and paper supercapacitors are tested for their performance in both aqueous and PVA gel electrolytes by using galvanostatic and cyclic voltammetry methods. A high specific capacitance of 270 F g−1 and an energy density value of 37 W h kg−1 are achieved for devices with PVA gel electrolytes. Furthermore, this device can maintain excellent specific capacitance even under high currents. This is also confirmed by another counter experiment with aqueous sulfuric acid as the electrolyte. The cycle life, one of the most critical parameters in supercapacitor operations, is found to be excellent (6000 cycles) and less than 0.5 % capacitance loss is observed. Moreover, the supercapacitor device is flexible and even after twisting does not show any cracks or evidence of breakage, and shows almost the same specific capacitance of 267 F g−1and energy density of 37 W h kg−1. This work suggests that a paper substrate can be a highly scalable and low-cost solution for high-performance supercapacitors. 相似文献
62.
Supercapacitors, or electrochemical capacitors, are a power storage system applied for harvesting energy and delivering pulses during short periods of time. The commercially available technology is based on charging an electrical double-layer (EDL), and using high surface area carbon electrodes in an organic electrolyte. This review first presents the state-of-the-art on EDL capacitors, with the objective to better understand their operating principles and to improve their performance. In particular, it is shown that capacitance might be enhanced for carbons having subnanometric pores where ions of the electrolyte are distorted and partly desolvated. Then, strategies for using environment friendly aqueous electrolytes are presented. In this case, the capacitance can be enhanced through pseudo-faradaic contributions involving i) surface functional groups on carbons, ii) hydrogen electrosorption, and iii) redox reactions at the electrode/electrolyte interface. The most promising system is based on the use of aqueous alkali sulfate as electrolyte allowing voltages as high as 2 V to be reached, due to the high overpotential for di-hydrogen evolution at the negative electrode. 相似文献
63.
Linlin Li Dr. Shengjie Peng Yanling Cheah Peifen Teh Jin Wang Grace Wee Yahwen Ko Dr. Chuiling Wong Prof. Madhavi Srinivasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):5892-5898
Novel, porous NiCo2O4 nanotubes (NCO‐NTs) are prepared by a single‐spinneret electrospinning technique followed by calcination in air. The obtained NCO‐NTs display a one‐dimensional architecture with a porous structure and hollow interiors. The effect of precursor concentration on the morphologies of the products is investigated. Due to their unique structure, the prepared NCO‐NT electrode exhibits a high specific capacitance (1647 F g?1 at 1 A g?1), excellent rate capability (77.3 % capacity retention at 25 A g?1), and outstanding cycling stability (6.4 % loss after 3000 cycles), which indicates it has great potential for high‐performance electrochemical capacitors. The desirable enhanced capacitive performance of NCO‐NTs can be attributed to the relatively large specific surface area of these porous and hollow one‐dimensional nanostructures. 相似文献
64.
综合ZnO-Al2O3-SiO2系和锗酸盐玻璃陶瓷的优点,采用熔融-晶化法首次制备了Ho3+/Yb3+共掺以ZnAl2O4为主晶相的ZnO-Al2O3-GeO2-SiO2系玻璃陶瓷。因[GeO4]四面体和[SiO4]四面体都是玻璃网络形成体,讨论了GeO2取代SiO2对玻璃陶瓷样品硬度及发光性能的影响,最终确定GeO2的取代量为10.55%(w/w)时,玻璃陶瓷综合性能最佳。在980 nm泵浦光的激发下,发现强的绿色(546 nm)和弱的红色(650 nm)上转换发光,并研究了不同Ho3+/Yb3+掺杂比对样品上转换发光的影响,最终结果表明当Ho3+/Yb3+掺杂比为1:11(n/n)时样品荧光强度最强,在绿色上转换发光材料方面具有潜在的应用。 相似文献
65.
Hao-Lin Hsu Milon Miah Shyamal Kumar Saha Jean-Hong Chen Lung-Chuan Chen Sheng-Yen Hsu 《Materials Today Chemistry》2021
Bundle-type mutil-walled carbon nanotubes (MWCNTs) composite electrode is the first investigation and publication for the supercapacitor application. According to the thermogravimetric analysis results, as-synthesized BCNTs are considered as the electrode materials for supercapacitors and electrochemical double-layer capacitor in this study. The Brunauer–Emmett–Teller specific surface area of as-prepared bundled carbon nanotubes (BCNTs) is 95.29 m2/g given to a type III isotherm and H3 hysteresis loops. Slow scanning rates promote and enhance to achieve high Cb because of the superior conductivity of CNT bundles and one side close-layered Ni/Mg/Mo alloy inside the BCNT-based electrode and facile electron diffusivity between electrolyte and electrode. The specific capacitance Cs (1,560 F/g) is nearly equal to the maximum specific capacitance, which the BCNT-based composite electrode can actually be able to charge or fill in. The maximum energy density value is 195 Wh/kg with corresponding power density values of 0.21 kW/kg. Furthermore, the active 3D BCNTs material fabricated electrode enhances to contact the electrolyte directly and decreases the ion diffusion limitation. Electrochemical impedance spectroscopy spectrum summarized as the low-frequency area controls by mass transfer limitation, and the high-frequency area dominates by charge transfer of kinetic control. After 2,000 consecutive cyclic voltammetry sacnings and galvanostatic charge-discharge cycles at a current density of 1.67 A/g performs, the specific capacitance retentions of 3D BCNTs electrodes achieved 128.2 and 77.3%, respectively. Three-dimensional BCNT composite electrodes exhibit good conductivity and low charge transfer resistance, which is beneficial to fast charge transfer between the BCNTs electrode materials and electrolytes. 相似文献
66.
Energy storage using dielectric capacitors is a growing area of research and development. However, designing a highly performing dielectric capacitor is still a challenge. Despite the excellent results achieved in lead-based dielectrics, lead-free substitutes are essential because of the environmental concerns associated with lead-based products. The lead-free 1?x (0.94NaNbO3? 0.06SrZrO3)+ x Bi2O3 ceramics abbreviated NNSZ + xB for x = 0.0, 0.05, 0.1, 0.15, and 0.20 was fabricated via solid-state reaction. A recoverable energy density of 2.93 J cm?3 was obtained for NNSZ+0.1B, associated with high thermal stability (25–130 °C), excellent cycling (N = 105), and high efficiency (η) of 83.5%. Moreover, the introduction of Bi2O3 significantly improved the electrical insulation (?r at 1 kHz = 1608 and tan δ = 0.0038) and breakdown strength (380 kVcm?1) of NNSZ+0.1B by minimizing the formation of sodium, bismuth, and oxygen vacancies. The results obtained in this study provide a benchmark for further investigations on NaNbO3-based ceramics. More importantly, this study suggests that NNSZ + xB ceramics can be used in pulsed power technology. 相似文献
67.
Jutapol Jumpatam Bundit Putasaeng Narong Chanlek Prasit Thongbai 《Molecules (Basel, Switzerland)》2021,26(7)
The microstructure, dielectric response, and nonlinear current-voltage properties of Sr2+-doped CaCu3Ti4O12/CaTiO3 (CCTO/CTO) ceramic composites, which were prepared by a solid-state reaction method using a single step from the starting nominal composition of CCTO/CTO/xSrO, were investigated. The CCTO and CTO phases were detected in the X-ray diffraction patterns. The lattice parameter increased with increasing Sr2+ doping concentration. The phase compositions of CCTO and CTO were confirmed by energy-dispersive X-ray spectroscopy with elemental mapping in the sintered ceramics. It can be confirmed that most of the Sr2+ ions substituted into the CTO phase, while some minor portion substituted into the CCTO phase. Furthermore, small segregation of Cu-rich was observed along the grain boundaries. The dielectric permittivity of the CCTO/CTO composite slightly decreased by doping with Sr2+, while the loss tangent was greatly reduced. Furthermore, the dielectric properties in a high-temperature range of the Sr2+-doped CCTO/CTO ceramic composites can be improved. Interestingly, the nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were significantly enhanced. The improved dielectric and nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were explained by the enhancement of the electrical properties of the internal interfaces. 相似文献
68.
James P. Best Johannes Zechner Jeffrey M. Wheeler Rachel Schoeppner Marcus Morstein 《哲学杂志》2016,96(32-34):3552-3569
For the implementation of thin ceramic hard coatings into intensive application environments, the fracture toughness is a particularly important material design parameter. Characterisation of the fracture toughness of small-scale specimens has been a topic of great debate, due to size effects, plasticity, residual stress effects and the influence of ion penetration from the sample fabrication process. In this work, several different small-scale fracture toughness geometries (single-beam cantilever, double-beam cantilever and micro-pillar splitting) were compared, fabricated from a thin physical vapour-deposited ceramic film using a focused ion beam source, and then the effect of the gallium-milled notch on mode I toughness quantification investigated. It was found that notching using a focused gallium source influences small-scale toughness measurements and can lead to an overestimation of the fracture toughness values for chromium nitride (CrN) thin films. The effects of gallium ion irradiation were further studied by performing the first small-scale high-temperature toughness measurements within the scanning electron microscope, with the consequence that annealing at high temperatures allows for diffusion of the gallium to grain boundaries promoting embrittlement in small-scale CrN samples. This work highlights the sensitivity of some materials to gallium ion penetration effects, and the profound effect that it can have on fracture toughness evaluation. 相似文献
69.
《Current Applied Physics》2015,15(12):1624-1633
Nano-composite olivine LiMnPO4 (nC-LMP) was found to exhibit facile pseudo-capacitive characteristics in aqueous as well as non-aqueous electrolytes. We demonstrated employing nC-LMP as positive electrode in hybrid electrochemical capacitors namely Li-Ion hybrid capacitors (LIC). Adapting a simple CVD technique, nano-crystallites of LiMnPO4 were coated with carbon monolayers of ∼2 nm thick to circumvent its poor intrinsic electronic conductivity. The novelty is that the single crystallites were intimately covered with carbon ring and networked to the neighboring crystallites via the continuous carbon wire-like connectivity as revealed from HRTEM analysis. Single electrode faradic capacitance of 3025 Fg−1 (versus standard calomel reference electrode) was deduced for carbon coated LMP, the highest reported hitherto in Li+ aqueous electrolytes. Employing nC-LMP as working electrode versus an activated carbon (AC), we obtained a high specific energy of 28.8 Wh kg−1 with appreciable stability in aqueous electrolytes whereas in nonaqueous electrolyte there is an obvious increase in energy density (35 Wh kg−1) due to wider potential window. That is, a full cell version of LIC, AC|Li+|LMP, was fabricated and demonstrated its facile cycling characteristics via removal/insertion of Li+ within nC-LMP (positive electrode) and the electrosorption of Li+ into mesoporous carbon (AC) (negative electrode). Such cells ensured a typical battery-like charging and EDLC-like discharging characteristics of LIC type electrochemical capacitors (ECs) which are desired to enhance safety and energy densities. 相似文献
70.
《Current Applied Physics》2015,15(11):1384-1388
Thin-film multi-layer ceramic capacitors (MLCCs) were prepared using high-dielectric constant Bi2Mg2/3Nb4/3O7 thin-films deposited at room temperature via radio-frequency magnetron sputtering. The multi-layer capacitors, in sizes 0402, 0603 and 1005, were well equipped with both inner and outer Cu electrodes. The capacitances of the bi-layer capacitors were twice that of the single-layer version in sizes 0402, 0603, and 1005. The 200 nm-thick Bi2Mg2/3Nb4/3O7 thin-films would be suitable for thin-film multi-layer capacitor applications. 相似文献