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排序方式: 共有2138条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(2):1083-1091
α-Ni(OH)2 is a promising candidate of the currently commercialized β-Ni(OH)2 due to its higher theoretical discharge capacity in alkaline solution; however, its instability and poor conductivity plague the practical application. Herein, we propose α-Ni(OH)2 with Co doping and spherical structure to strengthen the stability and enhance the conductivity and use it as the cathode for nickel-metal hydride batteries. Studies show that proper Co doping promotes the electrochemical reaction between the active materials and the electrolyte due to the spherical α-Ni(OH)2 with enlarged interlayer distance and abundant hole channels, as well as high conductivity of Co, therefore, the obtained spherical α-Ni(OH)2 with 7 mol% Co doping delivers significantly improved discharge capability, which is 384.6 mAh g?1 at 70 mA g?1 (0.2 C), increased by 54.3 mAh g?1 compared with pure α-Ni(OH)2, and at a high current of 5 C, it still gives 269.4 mAh g?1, in contrast 218.5 mA g?1 for the pure α-Ni(OH)2. Besides, the cycling stability of the α-Ni(OH)2 with 7 mol% Co doping maintains 340 cycles at a capacity retention of 80% (1C), which is extended 110 cycles in contrast to the pure α-Ni(OH)2. These results provide the underpinning platform of α-Ni(OH)2 for battery applications with high discharge ability and cycle life. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(6):3918-3926
MgH2 is considered as a promising hydrogen storage material for on-board applications. In order to improve hydrogen storage properties of MgH2, the amorphous TiMgVNi3-doped MgH2 is prepared by ball milling under hydrogen atmosphere. It is found that the catalytic (Ti,V)H2 and Mg2NiH4 nanoparticles are in situ formed after activation. As a result, the amorphous TiMgVNi3-doped MgH2 exhibits enhanced dehydrogenation kinetics (the activation energy for hydrogen desorption is 94.4 kJ mol?1 H2) and superior cycle durability (the capacity retention rate is up to 92% after 50 cycles). These results demonstrate that the in situ formation of highly dispersed catalytic nanoparticles from an amorphous phase is an effective pathway to enhance hydrogen storage properties of MgH2. 相似文献
3.
《International Journal of Hydrogen Energy》2021,46(66):33186-33196
Additive doping is one of the effective methods to overcome the shortcomings of MgH2 on the aspect of relatively high operating temperatures and slow desorption kinetics. In this paper, hollow g-C3N4 (TCN) tubes with a diameter of 2 μm are synthesized through the hydrothermal and high-temperature pyrolysis methods, and then nickel is chemically reduced onto TCN to form Ni/TCN composite at 278 K. Ni/TCN is then introduced into the MgH2/Mg system by means of hydriding combustion and ball milling. The MgH2–Ni/TCN composite starts to release hydrogen at 535 K, which is 116 K lower than the as-milled MgH2 (651 K). The MgH2–Ni/TCN composite absorbs 5.24 wt% H2 within 3500 s at 423 K, and takes up 3.56 wt% H2 within 3500 s, even at a temperature as low as 373 K. The apparent activation energy (Ea) of the MgH2 decreases from 161.1 to 82.6 kJ/mol by the addition of Ni/TCN. Moreover, the MgH2–Ni/TCN sample shows excellent cycle stability, with a dehydrogenation capacity retention rate of 98.0% after 10 cycles. The carbon material enhances sorption kinetics by dispersing and stabilizating MgH2. Otherwise, the phase transformation between Mg2NiH4 and Mg2NiH0.3 accelerates the re/dehydrogenation reaction of the composite. 相似文献
4.
《Ceramics International》2022,48(7):9400-9406
In the present study, we prepared vacancy-engineered V2O5-x films for electrochromic (EC) applications. To investigate the vacancy effect of V2O5-x films with high EC performance capabilities, precursor concentrations of V-based sol solutions were varied at 1 wt%, 5 wt%, and 10 wt%. Among them, V2O5-x films with a precursor concentration of 5 wt% (V2O5-5wt%) showed superior EC performance outcomes due to the (001)-plane-oriented crystal structure, which provides high electrical conductivity with the oxygen vacancy (Vo). In addition, the gravel-like uniform surface morphology with the optimized film thickness provides a stable electrochemical reaction during the EC measurement. As a result, V2O5-5wt% exhibited fast switching speeds (2.1 s for coloration and 3.6 s for bleaching), high transmittance modulation (ΔT) (51.32%), high coloration efficiency (CE) (52.3 cm2/C), and excellent cycle stability (85.85% ΔT retention after 500 cycles). In addition, V2O5-5wt% showed energy storage capability of 443.7 F/g at a current density of 2 A/g, thus proving its potential for use in multi-functional applications. Therefore, these results provide valuable insight related to the engineering of vacancies in EC films to achieve high-performance EC devices and additional multi-functional applications. 相似文献
5.
Yu Han Xu Cheng Gaolei Zhao Wenjiang Qiang Bingxin Huang 《Ceramics International》2021,47(9):12104-12110
The Ni-rich LiNi0.83Co0.12Mn0.05O2 (NCM83) cathode materials have drawn intensive attention due to the high energy density and low cost. However, Ni-rich LiNi1-x-yCoxMnyO2 still has the fatal weakness of poor cycle stability, limiting its further wide application. Bulk doping is an effective means to enhance the cycle stability, yet the electrochemical performances are very sensitive to the doping quantity. Here a facile method of co-precipitation is adopted to coat (Ni0.4Co0.2Mn0.4)1-xAlx(OH)2+x on precursor particles of NCM83. Al ions diffuse evenly in the NCM83 particles after sintering. The cells are operated at a high cut-off voltage of 4.5 V. The discharge capacity of NCM83 is 187.8 mAh g?1, and decays fast with cycles. The doped sample even exhibits a higher discharge capacity of 195 mAh g?1, and the capacity retention is improved to 83.8% after 200 cycles. 相似文献
6.
In 1937, Sir H. A Krebs first published the Citric Acid Cycle, a unidirectional cycle with carboxylic acids. The original concept of the Citric Acid Cycle from Krebs’ 1953 Nobel Prize lecture illustrates the unidirectional degradation of lactic acid to water, carbon dioxide and hydrogen. Here, we add the heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex, connecting the original Citric Acid Cycle to the flow of energy and material. The heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex catalyses the first reaction of the Citric Acid Cycle, the oxidation of lactate to pyruvate, and thus secures the provision of pyruvic acid. In addition, we modify Krebs’ original concept by feeding the cycle with oxaloacetic acid. Our concept enables the integration of anabolic processes and allows adaption of the organism to recover ATP faster. 相似文献
7.
《Ceramics International》2020,46(8):11499-11507
In this study, NiCo2O4 with different morphologies were fabricated using carriers by homogeneous coprecipitation combined with a sintering method. The phase and microstructure were characterized by XRD, SEM, EDS, TEM and BET, and the catalytic performances were investigated by NaBH4 hydrolysis experiments. These studies revealed that the deposition morphology of NiCo2O4 can be adjusted by using different kinds of carrier templates, and the supported NiCo2O4 samples presented the pine-needle-like, network-like, ball-cactus-like and dandelion-like morphologies respectively. The optimal catalytic activity, durability and stability make the network-like NiCo2O4 an appropriate catalyst for hydrogen generation of NaBH4 hydrolysis. It was found that the network-like NiCo2O4 is the most reusable and durable catalyst for ten consecutive cycles and 100% hydrogen generation conversion rate without obvious decrease among these morphologies. 相似文献
8.
《International Journal of Hydrogen Energy》2020,45(4):3073-3085
In this study, a facile sonochemical strategy is used for the fabrication of CoFe2O4/MWCNTs hybrids as an electrode material for supercapacitor applications. FE-SEM image demonstrates the uniformly well-distributed MWCNTs as well as porous structures in the prepared CoFe2O4/MWCNTs hybrids, suggesting 3D network formation of conductive pathway, which can enhance the charge and mass transport properties between the electrodes and electrolytes during the faradic redox reactions. The as-fabricated CoFe2O4/MWCNTs hybrids with the MWCNTs concentration of 15 mg (CFC15) delivers maximum specific capacitance of 390 F g−1 at a current density of 1 mA cm−2, excellent rate capability (275 F g−1 at 10 mA cm−2), and outstanding cycling stability (86.9% capacitance retention after 2000 cycles at 3 mA cm−2). Furthermore, the electrochemical performance of the CFC15 is superior to those of pure CoFe2O4 and other CoFe2O4/MWCNTs hybrids (CFC5, CFC10 and CFC20), indicating well-dispersion MWCNTs and uniform porous structures. Also, as-fabricated asymmetric supercapacitor device using the CoFe2O4/MWCNTs hybrids as the positive electrode and activated carbon as the negative electrode materials shows the outstanding supercapacitive performance (high specific capacitance, superior cycling stability and good rate capability) for energy storage devices. It delivers a capacitance value of 81 F g−1 at 3 mA cm−2, ca. 92% retention of its initial capacitance value after 2000 charge-discharge cycles and excellent energy density (26.67 W h kg−1) at high power density (~319 W kg−1). 相似文献
9.
《Ceramics International》2020,46(8):12080-12087
(1-x) Ba(Zr0.2Ti0.8)O3-x Na0.5Bi0.5TiO3 (x = 0, 10, 20 30, 40, 50 mol%) (BZTN) ceramics are prepared by the traditional solid phase method. All BZTN ceramics exhibit a pseudo-cubic BZT based perovskite structure. Both the average grain size and the relaxor ferroelectricity of BZTN ceramics gradually increase with increasing NBT content. The Wrec of 3.22 J/cm3 and η of 91.2% is obtained for the BZTN40 ceramic at 241 kV/cm. BZTN40 ceramic also exhibits good temperature stability from room temperature to 150 °C and frequency stability from 1 Hz to 100 Hz. A PD of 0.621 J/cm3 and a t0.9 of 82 ns is obtained for the BZTN40 ceramic at 120 kV/cm. BZTN ceramics show application potential in energy storage and pulse power capacitors. 相似文献
10.
Improving the efficiency of a vapor compression cycle and using low GWP working fluids have become more important than ever due to the environmental concerns. A saturation cycle consisting of saturation compression and saturation expansion was proposed in order to improve a vapor compression cycle performance by reducing thermodynamic losses associated with single phase gas compression and isenthalpic expansion. The saturation cycle can be approached by multi-stage cycles with two-phase refrigerant injection. In this paper, the performance of saturation cycle was theoretically investigated for low GWP working fluids including natural fluids under ASHRAE standard operating conditions and extreme heating condition. The simulation results indicate that the benefit of using the multi-stage cycle is higher for the cycle with higher pressure ratio. When the saturation cycle technique (four-stage cycle) is applied, the COP improvements of D2Y60 (mixture of R32 and R1234yf), CO2 and propane are 46.9%, 43.2% and 38.2%, respectively under extreme heating condition. 相似文献