Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Self-assembled three-dimensional Si/carbon frameworks as promising lithium-ion battery anode
No full textSilicon, the most prospecting anode material for lithium batteries, has been receiving enormous attention, but silicon-based composite materials exhibit severe problems of structural instability and insufficient electron/ion conductivity, which is a major bottleneck limiting its practical applications. Herein, a three-dimensional (3D) silicon/carbon framework, CHSP, is designed to solve this problem. The nano-Si particles are well fixed by the interconnected porous conducting network, which not only enhances the ion/electron transport, but also buffers the volume change of Si effectively. As a result, the CHSP exhibits satisfying rate performance and a reversible capacity of as high as 1332 mA h g-1 at 1000 mA g-1 for 200 cycles. This research provides a practical approach to improve silicon anode performance in aspects of cycling stability and facile 3D structures synthesis process
Revealing the wetting mechanism of Li plus -doped ionic liquids on the TiO2 surface
No full textThe sensible design of ionic liquid (IL)-based application relies on a thorough knowledge of the structure and characteristics of electrolyte-electrode interfaces. Here, the wetting processes of the Li+-doped ILs droplets on the TiO2-B(10 0) surface are investigated by molecular dynamics simulation. According to the spatial distributions of components, doped Li+ prefers to substitute the ILs and adsorb to the sub-strate, causing the orientation changes of the ILs, weakening the ILs-substrate interaction, and slowing down the wetting process significantly. As Li+ concentration rises from 0 to 80 %, the contact angle increases from 86.97 to 131.18 degrees, inducing the hydrophilic-to-hydrophobic transition. On the contrary, heating up would reduce the contact angle by extending the contact length and enhancing the maximum density of Li+-doped ILs at the interface. These quantitative results prove that the dense adjacent layer in the interface induced by the strong adsorption of Li+ dominates the wetting process of Li+-doped ILs. (c) 2022 Elsevier Ltd. All rights reserved
A new correlation model for predicting the melting and boiling temperatures of the Lennard-Jones systems
No full textThe Lennard-Jones (LJ) potential function is widely employed in molecular dynamics simulations. In this study, the LJ potentials under different characteristic diameter sigma and characteristic energy epsilon were simulated, and the changes in properties such as number density, total energy, phase transition latent heat, and phase transition temperature were detailed. With the increase of sigma, the melting and boiling temperatures of the LJ systems and the thermodynamic temperature range corresponding to liquid decrease, while with the increase of epsilon, the melting and boiling temperatures and the thermodynamic temperature range of liquid increase. Moreover, the phase transition latent heat hardly changes with the increase of sigma, but significantly increases with epsilon. The number densities at the melting and boiling temperatures are only dependent on sigma, and are not nearly influenced by epsilon. Furthermore, based on a modified Lindemann's melting criterion, a new empirical correlation model is proposed to predict the melting and boiling temperatures of the LJ systems, where the phase transition points are in good agreement with the experimental values. For the melting point, the absolute error between the formula and the experimental measurement for inert gas and methane is no more than 10 K, and for the boiling point, the absolute error is less than 15 K. By this new presented model, some thermophysical properties of the LJ potential systems can be quickly obtained and evaluated
Clean preparation of mixed trivalent and quadrivalent vanadium electrolyte for vanadium redox flow batteries by catalytic reduction with hydrogen
No full textThe vanadium redox flow battery (VRFB) is a promising technology for large-scale stationary energy storage systems. However, the high preparation cost of mixed valent vanadium electrolyte hinders the large-scale commercial application of VRFB. In this work, a simple, green and low-cost method is proposed to prepare the mixed valent vanadium electrolyte for VRFB. The clean hydrogen is chosen as the reducing agent to obtain trivalent vanadium ions from quadrivalent vanadium ions. The Pt/C material is used as the catalyst to accelerate the reduction rate at atmospheric pressure. The impurity-free mixed valent vanadium electrolyte, with a mean valence number of 3.5, prepared by the catalytic reduction process exhibits excellent battery performance with CE of 93% and EE of 85%. Furthermore, a catalytic reactor using Pt/C decorated graphite felt is designed and used to continuously produce the mixed valent vanadium electrolyte. According to the result of simple cost analysis, the proposed catalytic hydrogen reduction process can reduce theoretically the manufacturing cost by approximately 22.6% compared with the present industrial electrolytic process. As a consequence, the simple
Clean preparation of mixed trivalent and quadrivalent vanadium electrolyte for vanadium redox flow batteries by catalytic reduction with hydrogen
No full textThe vanadium redox flow battery (VRFB) is a promising technology for large-scale stationary energy storage systems. However, the high preparation cost of mixed valent vanadium electrolyte hinders the large-scale commercial application of VRFB. In this work, a simple, green and low-cost method is proposed to prepare the mixed valent vanadium electrolyte for VRFB. The clean hydrogen is chosen as the reducing agent to obtain trivalent vanadium ions from quadrivalent vanadium ions. The Pt/C material is used as the catalyst to accelerate the reduction rate at atmospheric pressure. The impurity-free mixed valent vanadium electrolyte, with a mean valence number of 3.5, prepared by the catalytic reduction process exhibits excellent battery performance with CE of 93% and EE of 85%. Furthermore, a catalytic reactor using Pt/C decorated graphite felt is designed and used to continuously produce the mixed valent vanadium electrolyte. According to the result of simple cost analysis, the proposed catalytic hydrogen reduction process can reduce theoretically the manufacturing cost by approximately 22.6% compared with the present industrial electrolytic process. As a consequence, the simple
Sources apportionment of water-soluble inorganic salts in CPM from coal-fired power plants with different emission control technologies
No full textDifferent control technologies to reduce emissions of sulfur oxides and nitrogen oxides from coal-fired boilers have been adopted globally, leading to significant reductions in these gas emissions, especially over the past several years in China. Comparatively, little attention has been paid to the potential effects of these control technologies on particulate matter (PM) emissions, especially condensable particulate matter (CPM), which is harmful to the atmosphere and human health. In this study, we measured filterable and condensable PM emissions in five coal-fired commercial-scale boilers installed with SNCR or SCR for NOx control and wet, semidry, or dry flue gas desulfurization (FGD) for SO2 emission controls. Water-soluble ionic components in PM were analyzed. The experimental results show that the CPM accounts for 55.9% to 95.1% of total particulate matter (TPM) and is composed primarily of water-soluble SO42-and NH4+, with (NH4)2SO4 being the dominant CPM aerosols. Experimental results also reveal that the flue gas emission control technology significantly affects CPM emission from coal-fired boilers. Since the production of (NH4)2SO4-rich CPM results from the use of ammonia solution for NOx reduction, boilers emit more CPM with SNCR than with SCR because the former operates with a higher ammonia/NOx ratio than the latter. Additionally, the CPM emission is related to the FGD technology installed. Boilers installed with wet FGD emit the lowest CPM, followed by semidry and dry FGDs, because of their decreased capabilities of dissolving and absorbing water-soluble components