Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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CO2 Etching Modulates Lithium and Sodium Storage Performance of Hard-Soft Carbon Composite-Based Freestanding Thick Electrodes
No full textCarbon-based materials are the most prospective anodes. Typically, a single carbon-based material is applied to different energy storage systems (EESs) without modification. However, the microcrystal structure of carbon plays a decisive role in the energy storage performance, and therefore, it should be adjusted when applied to different EESs. Here, a hierarchical porous carbon monomer monolith (HPCM) embedded with carbon nanotubes blooming on ZIF-67 was designed as a soft-hard carbon-based freestanding thick electrode for achieving high-energy lithium-ion and sodium-ion batteries. HPCM is resorcinol-formaldehyde (RF) resin-derived carbon, mainly composed of hard carbon, which has outstanding mechanical properties, a high surface area, and high porosity. Carbon nanotubes (CNTs) derived from ZIF-67 have extraordinary electronic conductivity, which provides soft carbon. High-temperature CO2 etching was performed to adjust the microcrystal structure, and the lithium/sodium storage performance of the electrode was evaluated. After CO2 etching, the materials lose almost half their weight (mainly hard carbon), and pseudocapacitive contribution decreases for both lithium-ion and sodium-ion batteries, whereas the specific capacity increases for lithium-ion batteries and decreases for sodium-ion batteries. Capacities of 5.96 mAh cm-2 (areal) and 132.48 mAh cm-3 (volumetric) were achieved for lithium storage, and those for sodium storage were 2.31 and 51.24 mAh cm-3, respectively. In summary, it is significant to adjust the microcrystal structure of carbon-based electrodes, and this study provides related experience for lithium and sodium storage
Magnetic field intensified electrodeposition of low-concentration copper ions in aqueous solution
No full textA large amount of low-concentration copper ion solution is generated during the recycling process of lithium-ion batteries. Low efficiency and poor selectivity for electrodeposition recovery of low-concentration copper ion solution due to slow ion migration rate. To increase the ion transfer rate of the diffusion layer, the low-concentration copper ion solution was pre-magnetized or in-situ magnetized for electrodeposition. Results indicated that the pre-magnetized electrolyte or magnetic field assisted-electrodeposition process could change the hydrogen bond structure, increase the solution viscosity, reduce the interface transfer resistance (Rct) and the transfer coefficient of copper ions in the diffusion layer, while reduce the radius of hydrated particles, the symmetry of the hydrated ion structure, and the activation energy of the reaction. As a result, the electrolysis efficiency increased from 22.1 to 32.3% for 0.01 mol/L CuSO4 solution, and from 92.3 to 98.1% for 0.1 mol/L CuSO4 solution after pre-magnetization
Recovery and kinetics of gold and vanadium from vanadium-bearing carbonaceous gold by chlorination roasting-acid leaching
No full textThe idle mining or flotation decarburization of vanadium-bearing carbonaceous gold ores polluted the environment and wasted resources. In this paper, the volatilization behavior of calcined gold and the extraction kinetics of vanadium from calcined slag were analyzed to increase the high-value utilization efficiency of double refractory gold deposits. The results showed that the high-temperature chlorination efficiency of gold increased with the increase of calcium chloride dosage. At the same time, the oxidation effect of vanadium in roasting slag is also improved, which reduces the cost of extracting vanadium from roasting slag by acid. the vanadium leaching ratio of 83.3% when the calcium chloride amount of 10%, the roasting temperature of 1000celcius, the roasting time of 240min, and the airflow rate of 1L/min, and the gold volatilization rate of 89.9%. The high-temperature chlorination reaction of gold and the acid leaching reaction of vanadium from calcined slag were also controlled by the interfacial chemical reaction. The apparent activation energy of the high-temperature chlorination of gold and the acid leaching of vanadium from calcined slag is calculated to be E = 71.61kJ/mol and 40.82kJ/mol, respectively. Suggested that gold recovery from vanadium-bearing carbonaceous gold ores was achieved using chlorination heat treatment. Also, the possibility of recovering vanadium from the roasting slag was verified by acid leaching experiments
Revealing the rate-limiting electrode of lithium batteries at high rates and mass loadings
No full textLithium-ion batteries with superior capacities and rate performance are needed due to the soaring demands for higher energy and power device requirements. However, the main hurdle on achieving this predominately results from the poor rate performance of electrode, which is related to thermodynamic limitations and slow kinetics. To determine the rate-limiting electrode in NMC622 vs graphite cells, a methodology based upon the galvanic intermittent titration technique, for investigating the diffusion and reaction kinetics from the observed over -potential at each electrode has been developed. Variable current densities have been used to simultaneously extract the thermodynamic and kinetic properties of each electrode with increasing mass loading. Graphite is observed to reach its thermodynamic limits quicker than NMC, due to the flat plateaus and overpotentials observed from the charge transfer kinetics and mass transport. At high rates and high mass loadings, the graphite electrode is responsible for limiting both Li+ diffusion and reaction rates in full cells. Slow diffusion kinetics are caused by the transport of the electrolyte in the porous electrode, which limits the availability of Li+ for reaction at the surface of graphite. This methodology is proposed as a fast single technique for comprehensively parameterizing the rate limitations observed in a full cell configuration
Second-level discipline construction of China Special Equipment Inspection & Research Institute[2021XKTD004]
No full textMetal-coordination and surface adhesion-assisted molding enabled strong, water-resistant carboxymethyl cellulose films
No full textDeveloping renewable and biodegradable materials derived from cellulose is an attractive strategy to replace petroleum-derived plastics. In this study, metal ions (Cu2+, Fe3+, and Al3+) were added as a green binder into carboxymethyl cellulose (CMC) films to improve their mechanical properties and water resistance capacity. The tensile strengths of CMC-Al3+ films were 133 MPa and 99 MPa at 43 % and 97 % humidity, respectively, which were comparable to or greater than those of the majority of commercially available plastics. Additionally, we proposed an interfacial adhesion-assisted molding strategy for forming cellulose-based films, avoiding film wrinkles and unevenness during drying and metal-coordination formation. The resultant films exhibited high transparency, excellent mechanical properties, water resistance capacity, ultraviolet light (UV) shielding, and antibacterial activity. In summary, the biodegradable, eco-friendly, excellent application performance, and adaptability of CMC-Mn+ (Mn+: polyvalent metal ions) films open new prospects as a viable alternative to non -biodegradable plastics
Kinetic modelling and experimental validation of single large particle combustion of coal char
No full textUnderstanding apparent kinetics of single large fuel particle combustion is of significance to the design and optimization of grate-firing and circulating fluidized bed boilers. Based on the concept of finite reaction zone approximation, a simple heterogeneous single particle model was formulated to consider the effects of external gas film, ash layer and chemical reaction simultaneously. To validate the proposed model and gain insight into the prevailing rate-controlling mechanism during the single particle combustion process at different combustion temperatures and particle sizes, the experiments on the combustion of coal char powder and single large char particles were carried out in a thermal gravimetric analyzer and a bench scale fixed-bed reactor, respectively. The intrinsic and apparent kinetics as well as the effective reacting zone thickness of single large particle combustion were quantified by combining theoretical analyses and experimental data. Both the bulk flow temperature and particle size have a remarkable influence on the global reactivity. The rate-controlling process was found to shift from the intrinsic chemical reaction to ash layer diffusion and return again to the intrinsic kinetics at the burnout stage. Particularly, an external effectiveness factor was defined as a function of conversion degree to better describe the ash diffusion effect on the apparent reactivity of large particles. The proposed model is physically general but simple enough to be incorporated into the computational fluid dynamic simulation of large-scale grate-firing and fluidized bed boilers
Single-Atom-Kernelled Nanocluster Catalyst
No full textTo propose the concept of single-atom-kernelled nanocluster, we synthesized a Pd-based trimetal nanocluster with a single-Ag atom-kernel for the first time by introducing some steric hindrance factors and employing a joint alloying strategy that combines the coreduction with an antigalvanic reduction (AGR). Although the AGR-derived Pd-based trimetal nanoclusters with single-silver atom kernels have low contents of gold, they show higher activity and selectivity than those of the bimetal precursor nanocluster in the electrocatalytical reduction of CO2 to CO. Furthermore, it is revealed that the kernel single atoms from both Au4Pd6(TBBT)(12) and Au3AgPd6(TBBT)(12) are not the active sites for catalysis, but greatly influence the catalytical performance by effecting the electronic configuration. Thus, it is demonstrated that the single-atom-kernelled nanocluster can not only improve the precious metal utilization (even to 100%) but also better the properties and provide insight into the structure-property correlation for metal nanoclusters
Bi-layer coarse-grained DPM of gas-solid systems with mesoscale heterogeneity resolved
No full textCoarse-grained discrete particle models (CGDPMs) that treat a group of real particles as a coarse-grained particle (CGP) are potentially capable of simulating industrial-scale gas-solid systems. However, the use of large CGPs decreases the spatial resolution for fluid computation, such that the detailed hydrodynam-ics of mesoscale structures cannot be captured accurately. In this study, the CGPs were coupled with gas flow at fine scale through weight function to describe the mesoscale heterogeneity in fluid velocity, solid concentration and interphase forces, which accurately reproduced experimental results of fluidization, in terms of bed expansion, bubble behaviors and voidage distribution. However, this extension incurred high computational cost due to large amounts of fluid cells. To speed up the computation, the gas flow was relaxed under frozen CGP configurations to evaluate the interphase forces on-the-fly. A bi-layer CGDPM thus proposed was demonstrated to be nearly 20 times faster than original fine-grid CGDPM for comparable accuracy. (c) 2022 Published by Elsevier Ltd