Numerical simulation of lithium‐ion battery performance considering electrode microstructure

A spatially resolved three‐dimensional microscale model of a lithium‐ion battery half‐cell is developed and applied to periodic electrode microstructures made up of spherical particles following a bidisperse particle size distribution. The geometries of the periodic unit cells are derived from discrete element simulations using periodic boundary conditions. Three different particle arrangements, which consist of two layered structures and one mixed particle array, as well as three different compression rates, are considered. In the study, the cathode is assumed to consist of LiMn₂O₄ as active material. Layered particle arrangements comprising the particle fraction of the smaller particle size in the region close to the separator are found to be beneficial especially for high‐rate applications. According to the simulation results, the high‐rate capability is reduced upon compression of the electrode microstructures. Copyright © 2015 John Wiley & Sons, Ltd.     

The influence of different water types and brewing durations on the colloidal properties of green tea infusion

Green tea infusions were prepared with three different water types: distilled water, commercial mineral water and CaCl₂ added distilled water (at 20 mg L^?1). The impact of different water type on the colloidal particle parameters, namely size, polydispersity index (PDI) and zeta potential, was examined within 24 h. Our results indicate that distilled water green tea infusion (DWT) brewed at 80 °C for 5 min contained the smallest particles (242.17 ± 11.78 nm) as examined by dynamic light scattering (DLS). Moreover, DWT showed smaller size increase during the 24 h storage than that of mineral water tea and CaCl₂ added water tea infusion. The morphology characteristics of green tea infusion particles were visualised by transmission electron microscope (TEM) which revealed that green tea infusion particles had heteromorphic shapes. Our results suggest that mineral composition of water impacts the colloidal size and stability of green tea infusion. Additionally, DLS and TEM could be useful tools to provide colloidal information which is important to understand quality characteristics of green tea infusion during processing and storage.     

碱化插层二维过渡金属碳化物的制备及其对铀酰离子的电化学检测

二维过渡金属碳化物(MXenes)具有良好的电化学性能与辐照稳定性, 其在放射性核素电化学检测领域有潜在应用价值。本研究通过碱活化的方式处理碳化钛型MXene(Ti₃C₂T_x), 随后将钾插层的Ti₃C₂T_x(K-Ti₃C₂T_x)负载到玻碳电极(GCE)上得到K-Ti₃C₂T_x/GCE修饰电极。采用XRD、SEM、XPS等手段分别对Ti₃C₂T_x和K-Ti₃C₂T_x进行分析表征, 并进一步研究了K-Ti₃C₂T_x/GCE对痕量铀酰离子(UO₂²⁺)的电化学检测性能。循环伏安(CV)实验结果表明, 相比于GCE电极, K-Ti₃C₂T_x/GCE修饰电极对UO₂²⁺的电化学响应显著增强。进一步使用差分脉冲伏安法(DPV)扫描, 发现pH=4.0时, K-Ti₃C₂T_x/GCE修饰电极对UO₂²⁺在铀浓度0.5~10 mg/L范围内呈现良好的线性检测关系, 本方法的检测限为0.083 mg/L(S/N=3), 稳定性和重复性好。     

Exploration of amorphous hollow FeOOH@C nanosphere on energy storage for sodium ion batteries

Sodium ion batteries (SIBs) have enjoyed a high profile in recent years and gradually been commercialized to supplement the lithium-ion batteries system. However, the large volume expansion of anode materials within discharging and low electrical conductivity hinder the application of SIBs. In this work, a FeOOH@C composite was synthesized with the use of hydrothermal method and pyrolyzing of polydopamine. The amorphous FeOOH exhibits a hollow spherical structure to offer free space for buffering the volumetric variation. Furthermore, the outer carbon served as a protective shell could maintain the sphere integrity and enhance the electrical conductivity. Hence, benefiting from the achieved synergy of the hollow architecture, amorphous structure and carbon shell, the composite presented a long cycle life (316 mA h g^?1 after 500 cycles at a current density of 100 mA g^?1 and 234.5 mA h g^?1 after 400 cycles at 2 A g^?1) and high-rate performance (180 mA h g^?1 at 5 A g^?1), revealing a potential to be a promising candidate for electrode material of SIBs.     

A Multiscale-Porous Anion Exchange Membrane for Convenient and Scalable Electrokinetic Concentration of Cationic Species

A device able to electrokinetically concentrate cationic samples has many potential medical and industrial applications, but until now has remained undeveloped due to the lack of a commercial anion-permselective material leading to a prohibitively complex fabrication procedure. Herein, a novel multiscale-porous anion exchange membrane (MP-AEM) that enables the convenient and scalable electrokinetic concentration of cationic species is proposed. A mechanically enhanced multiscale-porous structure with a solid framework is realized by adopting polyester resin as an additive to overcome the intrinsic limitations of the AEM material. The scalable MP-AEM-embedded electrokinetic concentrator is devised based on the peculiar properties of the MP-AEM that for allow both ion and fluid transport. With the MP-AEM, the concentrator is fabricated in a highly streamlined manner consisting only of a simple insertion and assembly. The concentration performance of the MP-AEM-embedded electrokinetic concentrator is demonstrated with a positively charged fluorescent dye and a fluorescein-labeled protein, and the results show enrichment factors of 250 and 500, respectively. The MP-AEM makes cationic electrokinetic concentration more accessible and scalable, thereby enabling further progress in a wide range of fields.     

Failed Neuroprotection of Combined Inhibition of L-Type and ASIC1a Calcium Channels with Nimodipine and Amiloride

Effective pharmacological neuroprotection is one of the most desired aims in modern medicine. We postulated that a combination of two clinically used drugs—nimodipine (L-Type voltage-gated calcium channel blocker) and amiloride (acid-sensing ion channel inhibitor)—might act synergistically in an experimental model of ischaemia, targeting the intracellular rise in calcium as a pathway in neuronal cell death. We used organotypic hippocampal slices of mice pups and a well-established regimen of oxygen-glucose deprivation (OGD) to assess a possible neuroprotective effect. Neither nimodipine (at 10 or 20 µM) alone or in combination with amiloride (at 100 µM) showed any amelioration. Dissolved at 2.0 Vol.% dimethyl-sulfoxide (DMSO), the combination of both components even increased cell damage (p = 0.0001), an effect not observed with amiloride alone. We conclude that neither amiloride nor nimodipine do offer neuroprotection in an in vitro ischaemia model. On a technical note, the use of DMSO should be carefully evaluated in neuroprotective experiments, since it possibly alters cell damage.     

Strain‐rate‐dependent mechanical properties of polypropylene separator for lithium‐ion batteries

The mechanical integrity of battery separators is critical for battery safety and durability. A comprehensive study of strain‐rate‐dependent tensile and puncture properties of a polypropylene lithium‐ion battery separator is presented here with a new model. Due to anisotropy of the polymeric membrane, tensile testing was conducted for different directions. Results showed that tensile strength and elastic modulus were increased 1000% and 500%, respectively, for different directions. It was also demonstrated that tensile strength changed 10 to 25% with strain rate (1.67 × 10^?4 to 1.67 × 10^?1 s^?1) for different directions. An equation was obtained for the first time for flow stress versus strain rate at varied tensile directions with respect to machine direction. Moreover, puncture testing was performed and it was shown that puncture strength was increased 140% with increasing strain rate from 0.25 to 250 mm min^?1. Two failure modes were also observed in puncture samples. Finally, Eyring's model was used to calculate activation enthalpy of the porous polypropylene separator. © 2020 Society of Chemical Industry     

High-resolution FIB-TEM-STEM structural characterization of grain boundaries in the high dielectric constant perovskite CaCu3Ti4O12

In this work, the grain boundaries composition of the polycrystalline CaCu₃Ti₄O₁₂ (CCTO) was investigated. A Focused Ion Beam (FIB)/lift-out technique was used to prepare site-specific thin samples of the grain boundaries interface of CCTO ceramics. Scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray spectrometry (EDXS) and Electron Energy Loss Spectroscopy (EELS) systems were used to characterize the composition and nanostructure of the grain and grain boundaries region. It is known that during conventional sintering, discontinuous grain growth occurs and a Cu-rich phase appears at grain boundaries. This Cu-rich phase may affect the final dielectric properties of CCTO but its structure and chemical composition remained unknown. For the first time, this high-resolution FIB-TEM-STEM study of CCTO interfacial region highlights the composition of the phases segregated at grain boundaries namely CuO, Cu₂O and the metastable phase Cu₃TiO_4.     

Steady MHD Casson Ohmic heating and viscous dissipative fluid flow past an infinite vertical porous plate in the presence of Soret,Hall, and ion‐slip current

In the present study, the influence of Hall and ion‐slip current on steady magnetohydrodynamics mixed convective, Ohmic heating, and viscous dissipative Casson fluid flow over an infinite vertical porous plate in the presence of Soret effect and chemical reaction are investigated. The modeling equations are transformed into dimensionless equations and then solved analytically through the multiple regular perturbation law. Computations are performed graphically to analyze the behavior of fluid velocity, temperature, concentration, skin friction, Nusselt number, and Sherwood number on the vertical plate with the difference of emerging physical parameters. This study reflects that the incremental values of Casson fluid parameter and Schmidt number lead to reduction in velocity. However, fluid velocity rises due to enhancement of ion‐slip parameter but an opposite effect is observed in case of Hall parameter. In addition, the Sherwood number declines with enhancing dissimilar estimators of the chemical reaction, Schmidt number, as well as Soret number.     

溶液浓差能驱动的逆电渗析反应器制氢实验研究

低品位热能制氢技术首先是将热能转换为溶液浓差能，然后通过逆电渗析（RED）反应器将溶液浓差能转换成氢能。为了验证RED反应器能将溶液浓差能转换为氢能，探索关键运行参数变化对能量转换过程的影响。设计了一个由40个膜对所构成的RED反应器，以NaCl水溶液为工作溶液，NaOH水溶液为电极液的制氢系统。通过改变浓/稀溶液入口浓度，溶液过膜流速以及输出电流来考察对RED反应器产氢率、制氢效率和能量转换效率的影响。实验结果发现，浓/稀溶液入口浓度，过膜流速变化均会影响RED反应器的输出电流。在外电路短接条件下，输出电流越大，反应器产氢率和制氢效率越高，但能量转换效率越低。