Strategic Approaches to the Dendritic Growth and Interfacial Reaction of Lithium Metal Anode

Utilization of lithium (Li) metal anode is highly desirable for achieving high energy density batteries. Even so, the unavoidable features of Li dendritic growth and inactive Li are still the main factors that hinder its practical application. During plating and stripping, the solid electrolyte interphase (SEI) layer can provide passivation, playing an important role in preventing direct contact between the electrolyte and the electrode in Li metal batteries. Because of complexities of the electrolyte chemical and electrochemical reactions, the various formation mechanisms for the SEI are still not well understood. What we do know is that a strategic artificial SEI achieved through additives electrolyte can suppress the Li dendrites. Otherwise, the dendrites keep generating an abundance of irreversible Li, resulting in severe capacity loss, internal short-circuiting, and cell failure. In this minireview, we focus on the phenomenon of dendritic Li-growth and provide a brief overview of SEI formation. We finally provide some clear insights and perspectives toward practical application of Li metal batteries.     

Functionalization of multiwalled carbon nanotube via surface reversible addition fragmentation chain transfer polymerization and as lubricant additives

Polymer‐grafted multiwalled carbon nanotube (MWCNT) hybrid composite which possess a hard backbone of MWCNT and a soft shell of brush‐like polystyrene (PSt) were synthesized. The reversible addition fragmentation chain transfer (RAFT) agents were successfully immobilized onto the surface of MWCNT first, and PSt chains were subsequently grafted from sidewall of MWCNT via RAFT polymerization. Chemical structure of resulting product and the quantities of grafted polymer were determined by Fourier transform infrared, thermal gravimetric analysis, nuclear magnetic resonance, and X‐ray photoelectron spectra. Transmission electron microscopy and field emission scanning electron microscopy images clearly indicate that the nanotubes were coated with a polymer layer. Furthermore, the functionalized MWCNT as additives was added to base lubricant and the tribological property of resultant MWCNT lubricant was investigated with four‐ball machines. The results indicate that the functionalization led to an improvement in the dispersion of MWCNT and as additives it amended the tribological property of base lubricant. The mechanism of the significant improvements on the tribological properties of the functionalized MWCNT as additives was discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3014–3023, 2008     

Surface segregation of highly branched polymer additives in linear hosts

Entropy‐driven segregation of various branched and hyperbranched polymeric additives in chemically similar linear polymer hosts is studied using self‐consistent (SCF) mean‐field lattice simulations. The simulations account for the effect of molecular architecture on local configurational entropy in the blends, but ignores the effect of architecture on local density and blend compressibility. Star, dendrimer, and comb‐like additives are all found to be enriched at the surface of chemically identical linear host polymers. The magnitude of their surface excess increases with increased number of chain ends and decreases with increased segmental crowding near the branch point. Provided the number of arms and molecular weight of the branched additives are maintained constant, we find that the simplest branched architecture, the symmetric star, exhibits the strongest preference for the surface of binary polymer blends. We show that a single variable, here termed the “entropic driving force density,” controls the relative surface affinities of branched additives possessing a wide range of architectures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1788–1801, 2008     

An automated Hi-res tg/ms system for the characterisation of fuel transport additives

Volatilization and decomposition data are given for two polymer derivatives used as fuel oil additives.     

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Pulsed deuteron NMR line shapes have been analysed to characterize type and time scale of the phenylene group motion in glassy bisphenol-A polycarbonate. The motional mechanism involves-flips about theC ₁ C ₄ axis augmented by small angle fulctuations about the same axis, reaching a rms amplitude of ±35 at 380 K. The distribution of correlation times for the-flips is heterogeneous in nature and can be described either by a log-Gaussian or an asymmetric distribution with a more rapid decay at high correlation times comparable to the Williams-Watts distribution. From both distributions essentailly the same mean activation energy of 37 kJ/mol is obtained, whereas the temperature dependent width of the highly asymmetric distribution is somewhat smaller compared to the log-Gaussian distribution. Time scale and activation energy of the-flip motion are correlated to secondary mechanical relaxations. Low molecular mass additives, which suppress the mechanical relaxation, also hinder the phenylene motion for a substantial fraction of phenylene groups. The effect of additives is not only to shift the mean value of the distribution of correlation times to higher values but also to increase drastically the width of the distribution. The results of this work strongly suggest that the secondary mechanical relaxation and the large amplitude motions of the phenylene groups in polycarbonate are related.     

The effects of various foreign substances on the cloud point of Triton X 100 and Triton X 114

The nonionic surfactants Triton X 100 and Triton X 114 form isotropic micellar solutions around 25°C. One of the characteristic features of these solutions is the fact that at higher temperatures they undergo clouding and liquid-liquid phase separation. Addition of various additives to the surfactant solutions does change the temperature at which the clouding phenomenon occurs. In this paper such effect of additives on the clouding phenomenon of Triton X 100 and Triton X 114 are discussed.     

Application of capillary electrophoresis in migration studies of food contact materials – part 1: Substituted phenolic additives

A method has been developed to determine 11 phenolic antioxidants in the food simulants distilled water, 3% acetie acid, and 15% ethanol, using; micellar capillary electrophoresis (MCE). All the phenols could he analyzed within 35 min. The analytical recovery from spiked simulants was 80 to 119% except for 2,6-di-tert-butyl-4hydroxytoluenc (BHT) and octyl gallate, which could not be recovered from 3% acetic acid simulant. Calibration graph correlation coefficients for the 11 phenols were 0.982 to 0.999. Limits of detection (LoDs) were from 2.8 to 8.6 mg/L. These LoDs are well below European Union migration limits for these substances. It is concluded therefore that MCE offers a rapid and reliable analysis for the control of migration from plastics intended for food contact which employ these phenols as antioxidants.     

Selective Oxidation of n-Butane over VPO Catalyst Modified by Different Additives

A series of vanadyl pyrophosphate catalyst （VPO） modified by different additives have been prepared with the aim to study the performance for selective conversion of n-butane to maleic anhydride（MA）. The addition of various promoters improved the catalytic performance remarkably on both activity and selectivity. The correlation of activity and selectivity of the catalysts with their structure has been discussed. The increase in BET surface areas and surface redox sites leads to an enhanced activity. However, good selectivity can only be obtained on those surfaces with suitable surface acid sites.     

萘油制备新型水煤浆添加剂的研究

研究了如何利用萘油中的有效成分合成出性能良好的水煤浆添加剂。通过合理的正交试验设计和多元线性回归分析方法得到了合成萘油添加剂的较佳工艺条件,即在75 g的萘油中,加入浓H2SO4 30 mL,在160 ℃时磺化2 h;加入HCHO 25 mL,在105 ℃时缩合1.5 h。利用实验合成的萘油添加剂与纯萘磺酸甲醛缩合物作添加剂分别对庞庄煤进行制浆实验。结果表明,萘油添加剂性能良好,可显著降低萘油添加剂的成本。应用傅立叶变换红外光谱对萘油添加剂的结构进行了分析,测出萘油添加剂主要为含有－CH2－,－SO3－等基团的芳香族化合物。对萘油添加剂改善水煤浆性能的作用机理进行了初步探讨。