8 research outputs found
Robust Biomass-Derived Carbon Frameworks as High-Performance Anodes in Potassium-Ion Batteries
Potassium-ion batteries (PIBs) have become one of the promising candidates for electrochemical energy storage that can provide low-cost and high-performance advantages. The poor cyclability and rate capability of PIBs are due to the intensive structural change of electrode materials during battery operation. Carbon-based materials as anodes have been successfully commercialized in lithium- and sodium-ion batteries but is still struggling in potassium-ion battery field. This work conducts structural engineering strategy to induce anionic defects within the carbon structures to boost the kinetics of PIBs anodes. The carbon framework provides a strong and stable structure to accommodate the volume variation of materials during cycling, and the further phosphorus doping modification is shown to enhance the rate capability. This is found due to the change of the pore size distribution, electronic structures, and hence charge storage mechanism. The optimized electrode in this work shows a high capacity of 175 mAh g^{-1} at a current density of 0.2 A g^{-1} and the enhancement of rate performance as the PIB anode (60% capacity retention with the current density increase of 50 times). This work, therefore provides a rational design for guiding future research on carbon-based anodes for PIBs
Monte-Carlo calculation of fission process for neutron-induced typical actinide nuclei fission
A global potential-driving model with well-determined parameters is proposed by uniting the empirical asymmetric fission potential and the empirical symmetric fission potential, which can precisely calculate the pre-neutron-emission mass distributions for neutron-induced actinide nuclei fission. Based on the developed potential-driving model, Monte-Carlo code calculates the characteristics of fission reaction process for neutron-induced 241 Am fission. Typical calculated results, including yields, kinetic energy distributions, fission neutron spectrum and decay γ-ray spectrum, are compared with experimental data and evaluated data. It shows that the Monte-Carlo calculated results agree quite well with the experiment data, which indicate that Monte-Carlo code with the developed potential-driving model can reproduce and predict the characteristics of fission reaction process at reasonable energy ranges. Given the well predictions on the characteristics of fission reaction process, Monte-Carlo code with the developed potential-driving model can guide for the physical design of nuclear fission engineering
Monte-Carlo calculation of fission process for neutron-induced typical actinide nuclei fission
A global potential-driving model with well-determined parameters is proposed by uniting the empirical asymmetric fission potential and the empirical symmetric fission potential, which can precisely calculate the pre-neutron-emission mass distributions for neutron-induced actinide nuclei fission. Based on the developed potential-driving model, Monte-Carlo code calculates the characteristics of fission reaction process for neutron-induced 241 Am fission. Typical calculated results, including yields, kinetic energy distributions, fission neutron spectrum and decay γ-ray spectrum, are compared with experimental data and evaluated data. It shows that the Monte-Carlo calculated results agree quite well with the experiment data, which indicate that Monte-Carlo code with the developed potential-driving model can reproduce and predict the characteristics of fission reaction process at reasonable energy ranges. Given the well predictions on the characteristics of fission reaction process, Monte-Carlo code with the developed potential-driving model can guide for the physical design of nuclear fission engineering
Effect of Li<sub>6.4</sub>La<sub>3</sub>Zr<sub>1.4</sub>Ta<sub>0.6</sub>O<sub>12</sub> Fillers on the Interfacial Properties between Composite PEO-LiTFSI Electrolytes with Li Metal during Cycling
PEO-LiX
solid polymer electrolyte (SPE) with the addition of Li6.4La3Zr1.4Ta0.6O12 (LLZTO)
fillers is considered as a promising solid-state electrolyte
for solid-state Li-ion batteries. However, the developments of the
SPE have caused additional challenges, such as poor contact interface
and SPE/Li interface stability during cycling, which always lead to
potentially catastrophic battery failure. The main problem is that
the real impact of LLZTO fillers on the interfacial properties between
SPE and Li metal is still unclear. Herein, we combined the electrochemical
measurement and in situ synchrotron-based X-ray absorption near-edge
structure (XANES) imaging technology to study the role of LLZTO fillers
in directing SPE/Li interface electrochemical performance. In situ
XRF-XANES mapping during cycling showed that addition of an appropriate
amount of LLZTO fillers (50 wt %) can improve the interfacial contact
and stability between SPE and Li metal without reacting with the PEO
and Li salts. Additionally, it also demonstrated the beneficial effect
of LLZTO particles for suppressing the interface reactions between
the Li metal and PEO-LiTFSI SPE and further inhibiting Li-metal dendrite
growth. The Li|LiFePO4 batteries deliver long cycling for
over 700 cycles with a low-capacity fade rate of 0.08% per cycle at
a rate of 0.3C, revealing tremendous potential in promoting the large-scale
application of future solid-state Li-ion batteries
The decisive role of CuI-framework O binding in oxidation half cycle of selective catalytic reduction
Cu-exchanged zeolite is an efficient catalyst to remove harmful nitrogen oxides from diesel exhaust gas through the selective catalytic reduction (SCR) reaction. The SCR performance is structure dependent, in which a Cu with one adjacent framework Al (1AlCu) has lower activation energy in oxidative half-cycle than Cu with two adjacent framework Al (2AlCu). Using a combination of operando X-ray absorption spectroscopy, valence to core - X-ray emission spectroscopy and density functional theory calculations, here we showed that 1AlCu proceeds with nitrate mechanism, in which side-on coordination of O2 at a CuI(NH3)xOfw (fw = framework) is the rate-limiting step in the oxidation half-cycle. As a result, the CuI(NH3)xOfw at 1AlCu can easily yield a transient CuIINOx intermediate upon breaking of Cu-Ofw after interaction with NO. In the meantime, 2AlCu has high barriers for Cu-Ofw bond breaking and proceeds with dimer mechanism. Our results show the coexisting of both dimer and nitrate mechanism, in particular at high Cu loadings, in which controlling the strength of the Cu-Ofw coordination is key for the O-O split in the nitrate pathway
Study on grid inefficiency for mesh-type Frisch-grid ionization chambers
In this study, the grid inefficiency for a mesh-type Frisch-grid ionization chamber (FGIC) was investigated using the finite element method and Monte Carlo method. A grid inefficiency evaluation model was developed, which can determine the relationship between the physical parameters of the detector and the grid inefficiency with reasonable accuracy. An artificial neural network (ANN) was applied in the investigation of the grid inefficiency factor . The trained ANN was able to describe and predict the grid inefficiency factor with different physical parameters for the mesh-type FGIC. Thus, it can serve as a reference for the development of mesh-type FGICs and correct grid inefficiency measurements