Unveiling Organic Electrode Materials in Aqueous Zinc-Ion Batteries:From Structural Design to Electrochemical Performance

Aqueous zinc-ion batteries(AZIBs)are one of the most compelling alternatives of lithium-ion batteries due to their inherent safety and economics viability.In response to the growing demand for green and sustainable energy storage solutions,organic electrodes with the scalability from inexpensive starting materials and potential for biodegradation after use have become a prominent choice for AZIBs.Despite gratifying progresses of organic molecules with electrochemical performance in AZIBs,the research is still in infancy and hampered by certain issues due to the underlying complex electrochemistry.Strategies for designing organic electrode materials for AZIBs with high specific capacity and long cycling life are discussed in detail in this review.Specifically,we put emphasis on the unique electrochemistry of different redox-active structures to provide in-depth understanding of their working mechanisms.In addition,we highlight the importance of molecular size/dimension regarding their profound impact on electrochemical performances.Finally,challenges and perspectives are discussed from the developing point of view for future AZIBs.We hope to provide a valuable evaluation on organic electrode materials for AZIBs in our context and give inspiration for the rational design of high-performance AZIBs.

THEORETICAL EFFECTS OF MOLECULAR DIMENSION AND CONFIGURATION ON EFFECTIVE DIFFUSION COEFFICIENT OF MACROMOLECULES IN MICROPOROUS MEMBRANES

This paper presents a theoretical method for predicting the effective diffusion coefficient of macromolecules in the microporous membrfines in view of the effects of molecular dimension and configuration. On the basis of the hindered diffusion theory of spherical neutral macromolecules in a micropore of a long cylinder, the effects of molecular dimension and configuration are studied by defining two molecular dimensions:the mean projected radius to predict the concentration partition and the ' hydrodynamically equivalent sphere' radius to evaluate the hydrodynamic reverse drag force. The quantitative comparison shows that the effective diffusion coefficients for different macromolecules predicted by the present method are more consistent with the available published experimental data.

Correlating Fe source with Fe-N-C active site construction： Guidancefor rational design of high-performance ORR catalyst

Pyrolyzed Fe-Nx/C materials derived from Fe-doped ZIF-8 are recently emerged as promising alternativesto noble metal platinum-based catalysts towards oxygen reduction reaction （ORR） and elucidating the de-pendacne of Fe source on the active site structure and final ORR performance is highly desirbale for fur-ther development of these materials. Here, we designed and synthesized a series of Fe-N-C catalysts usingZIF-8 and various iron salts （Fe（acac）3, FeCI3, Fe（NO3）3） as precusors. We found that the iron precursors,mainly the molecular size, hydrolysis extent, do play a major role in determining the final morphology ofFe, namely forming the Fe-Nx coordination or Fe3C nanoparticles, as well as the site density, therefore,significantly affecting the ORR activity. Among the three iron sources, Fe（acac）3 is most advantageous tothe preferential formation of single-atom Fe-Nx active sites and the derived catalyst demonstrated bestORR performance.

Combined grain size, strain rate and loading condition effects on mechanical behavior of nanocrystalline Cu under high strain rates

Molecular dynamics simulations of nanocrystalline Cu with average grain sizes of 3.1 nm, 6.2 nm, 12.4 nm and 18.6 nm under uniaxial strain and stress tension at strain rates of 10^8 s^-1, 10^9 S^-1 and 10^10 s^-1 are performed to study the combined grain size, strain rate and loading condition effects on mechanical properties. It is found that the strength of nanocrystalline Cu increases as grain size increases regardless of loading condition. Both the strength and ductility of nanocrystalline Cu increase with strain rate except that there is no monotonic relation between the strength and strain rate for specimens under uni- axial strain loading. Moreover, the strength and ductility of specimens under uniaxial strain loading are lower than those under uniaxial stress loading. The nucleation of voids at grain boundaries and their subsequent growth characterize the failure of specimens under uniaxial strain loading, while grain boundary sliding and necking dominate the failure of specimens under uniaxial stress loading. The rate dependent strength is mainly caused by the dynamic wave effect that limits dislocation motion, while combined twinning and slipping mechanism makes the material more ductile at higher strain rates.

Shaping Taste: The Molecular Discovery of Rice Genes Improving Grain Size, Shape and Quality

Modern-day human life is absolutely dependent upon the food that we derive from our crop plants. We eat grains, fruits, roots, tubers and other structures, all of which are constructed via coordinated organ growth. Whilst plant organ identity is first established in apical meristems （vegetative and floral shoot meristems and root meristems）, and in other meristematic regions, the final size and shape of organs are defined by subsequent coordination of organ expansion in longitudinal and transverse axes.

Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography,respectively,and samples were collected to measure properties.According to the elemental analysis,molecular weight and 1H-NMR data,average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner(B-L)method and several corrections.And then,the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation,and the molecular size was gotten via the radius of gyration analysis.The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55-0.70 nm in vacuum and 0.60-0.90 nm in toluene solution.With molecular weight increasing,the molecular size in vacuum and toluene solution also increased.Due to the swelling behavior of solvent,the alkyl side chains of heavy oil molecule in solution were more stretched.Thus,the molecular size in toluene solution was larger than that in vacuum.

Molecular Size and Morphology of Single Chains of Poly（sulfobetaine methacrylate）

The effects of the concentration of sodium chloride in an aqueous solution（cNacl and the temperature on the molecular size of poly（sulfobetaine methacrylate）（PSBMA） were studied via viscometry and dynamic light scattering（DLS）. The morphology of single-chain PSBMA was determined by atomic force microscopy（AFM）. The results demonstrate that the hydrodynamic diameter of PSBMA can be expressed as a continuous function of CNaCl, with the molecular size of PSBMA increasing and eventually approaching an asymptotic value with increasing CNaCl. The molecular size of PSBMA at a lower CNaCI（0.04 mol/L） increases with increasing temperature, which is the opposite of the temperature effect at a higher CNaCl（2.0 mol/L）. Therefore, the internal structure of PSBMA chains in solutions with a low salt concentration differs from that in solutions with a high salt concentration. In addition, the morphology of single chains of PSBMA appears to be spherical, containing 89% void space, and the apparent size of the dried chains is almost identical to that in solution.

Preparation of a permanent magnetic hypercrosslinked resin and assessment of its ability to remove organic micropollutants from drinking water

A rapid and effective method based on a novel permanent magnetic hypercrosslinked resin W150 was proposed for the removal of organic micropollutants in drinking water. W150 was prepared by suspension and post-crosslinking reaction and found to possess a high specific surface area of 1149.7 m^2· g^-1, a small particle size of 50 μm to 100 μm, and a saturation magnetization as high as 8 emu.g1. W150 was used to eliminate nitrofurazone （NFZ） and oxytetracycline （OTC） from drinking water compared with commercial adsorbents XAD-4 and F400D. The adsorption kinetics of NFZ and OTC onto the three adsorbents well fitted the pseudo-second-order equation （r 〉 0.972）, and the adsorption isotherms were all well described by the Freundlich equation （r 〉 0.851）. Results showed that the reduction in adsorbent size and the enlargement in sorbent pores both accelerated adsorption. Moreover, the effect of particle size on adsorption was more significant than that of pore width. Given that the smallest particle size and the highest specific surface area were possessed by W150, it had the fastest adsorption kinetics and largest adsorption capacity for NFZ （180 mg·g-1） and OTC （200mg·g- 1）. For the adsorbents with dominant micropores, the sorption of large-sized adsorbates decreased because of the inaccessible micropores. The solution pH and ionic strength also influenced adsorption.