表面活性剂界面化学实验改进:实验与模拟融合的综合设计

本实验聚焦化学领域科技前沿,关注智慧教学发展,将计算化学相关理念及方法融入传统实验,对数据分析和体系可视化进行了改进。利用Packmol软件构建与实验体系相符的模型,用Gromacs软件计算分析各体系中表面活性剂的倾斜角、回转半径、径向分布函数、氢键及溶剂可及表面积等数据,从微观层面研究吸附特性。本综合实验能够使学生从原子尺度认识表面活性剂的吸附和乳化过程的微观变化,激发学生学习兴趣,提升了学生的软件应用能力及空间想象能力,丰富物理化学实验有关界面化学实验的课程设计。

High-performance PVDF-HFP based gel polymer electrolyte with a safe solvent in Li metal polymer battery

Poly(vinylidenefluoride-co-hexafluoropropylene)(PVDF-HFP)based gel polymer electrolytes are widely studied owing to their electrochemical stability and high dielectric constant.However,most gel polymer electrolytes show unsatisfied safety and interface compatibility due to excessive absorption of volatile and flammable liquid solvents.Herein,by using a safe solvent(N-methyl-2-pyrrolidone)with higher boiling(203℃)and flash points(95℃),we initiatively fabricate a flexible PVDF-HFP based gel polymer electrolyte.The obtained gel polymer electrolyte demonstrates a high ionic conductivity of 7.24×10^−4 S cm−1,an electrochemical window of 5.2 V,and a high lithium transference number of 0.57.As a result,the synthesized polymer electrolyte exhibits a capacity retention of 70%after 500 cycles at 0.5 C,and a discharge capacity of 86 mAh g−1 even at a high current rate of 10 C for LiFePO4 based Li metal batteries.Moreover,a stable Li plating/stripping for more than 500 h is achieved under 0.1 mAh at both room temperature and 70℃.Our results indicate that the PVDF-HFP polymer electrolyte is promising for manufacturing safe and high-performance Li metal polymer batteries.

“Polymer-in-ceramic” based poly(ε-caprolactone)/ceramic composite electrolyte for all-solid-state batteries

Inspired by the concept of "polymer-in-ceramic",a composite poly(ε-caprolactone)(PCL)/ceramic containing LiTFSI is prepared and investigated as a solid electrolyte for all-solid-state batteries.The composite with the optimum concentration of 45 wt% LiTFSI and 75 wt% Li1.5Al0.5Ge1.5(PO4)3(LAGP,NASICON-type structure) exhibits a high ionic conductivity(σi=0.17 mS cm-1) at 30℃,a transference number of 0.30,and is stable up to 5.0 V.The composite electrolyte is a flexible and self-standing membrane.Solid-state LiFePO4//Li batteries with this composite electrolyte demonstrate excellent cycling stability with high discharge capacity of 157 mA h g-1,high capacity retention of 96% and coulombic efficiency of 98.5% after 130 cycles at 30℃ and 0.1 C rate.These electrochemical properties are better than other PCL-based allsolid-lithium batteries,and validate the concept of "polymer-in-ceramic" by avoiding the drawback of lower conductivity in prior "polymer-in-ceramic" electrolyte at high concentration of the ceramic.

MoO2 nanoparticles/carbon textiles cathode for high performance flexible Li-O2 battery

Conventional Li-O2 battery is hardly considered as a next-generation flexible electronics thus far,since it is inflexible,bulk,and limited by the absence of the adjustable cell configuration.Here,we report a binder-free and flexible electrode of x wt%MoO2 NPs/CTs(x=6,16,and 28).A cell with 16 wt% MoO2 NPs/CTs displays a good cyclability over 240 cycles with a low overpotential of 0.33 V on the 1st cycle at a constant current density of 0.2 mA cm-2,a considerable rate performance,a superior reversibility associated with the desired formation and degradation of Li2O2,and a high electrochemical stability even under stringent bending and twisting conditions.Our work represents a promising progress in the material development and architecture design of O2 electrode for flexible Li-O2 batteries.

Unveiling and Alleviating Chemical“Crosstalk”of Succinonitrile Molecules in Hierarchical Electrolyte for High-Voltage Solid-State Lithium Metal Batteries

Succinonitrile-based plastic crystal electrolytes have emerged for high-energy-density Li metal batteries in terms of their superior ambient ionic conductivity,low flammability,and benign compatibility with high voltage cathode,but are hampered by inherent instabilities toward Li anodes.Constructing hierarchical solid electrolytes structure is a fundamental approach to protect Li anode from succinonitrile attacks,with succinonitrile-based oxidation-resistance layer facing high voltage cathode and reduction-tolerant layer contacting Li anode.However,free succinonitrile molecules in succinonitrile-based electrolyte layer can diffuse across the electrolyte/electrolyte interface and further reach Li anode surface during the battery cycle.This chemical“crosstalk”cause reduction-tolerant electrolyte layer to fail to protect the Li anode from the attacks of free succinonitrile molecules.Nano Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)is introduced creatively into succinonitrile-based electrolyte layer.By taking advantage of the complexation between La atoms in Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)and N atoms in succinonitrile,the free succinonitrile molecules are successfully immobilized in succinonitrile-based electrolyte layer.The resulting low resistance and highly durable solid electrolyte interphase and cathode electrolyte interphase endow NCM622||Li batteries with remarkable cycle stability.Our research provides a new idea for the real application of plastic crystal electrolytes in high voltage solid-state lithium metal batteries.

Hierarchical N-doped carbon nanocages/carbon textiles as a flexible O2 electrode for Li–O2 batteries

The conventional Li–O2 battery(LOB)has hardly been considered as a next-generation flexible electronics thus far,since it is bulk,inflexible and limited by the absence of an adjustable cell configuration.Here,we present a flexible Li–O2 cell using N-doped carbon nanocages grown onto the carbon textiles(NCNs/CTs)as a self-standing and binder-free O2 electrode.The highly flexible NCNs/CTs exhibits an excellent mechanic durability,a promising catalytic activity towards the ORR and OER,a considerable cyclability of more than 70 cycles with an overpotential of 0.36 V on the 1 stcycle at a constant current density of 0.2 m A/cm2,a good rate capability,a superior reversibility with formation and decomposition of desired Li2 O2,and a highly electrochemical stability even under stringent bending and twisting conditions.Our work represents a promising progress in the material development and architecture design of O2 electrode for flexible LOBs.

Multilayer polyethylene separator with enhanced thermal properties for safe lithium-ion batteries Author links open overlay panel

The separator plays an important part in battery safety and performance.Polyolefin separators are widely used in commercial Lithium-ion batteries(LIBs),owing to their excellent properties,but they suffer from serious thermal shrinkage and poor electrolyte wettability.Thus,a multilayer separator(ASPESA)is developed by coating two thin layers of low-density polyethylene(LDPE)and Al_(2)O_(3)on both sides of a polyethylene membrane using a facile and environmentally friendly casting technique.The ASPESA separator demonstrates a shutdown function at 120℃and shows enhanced thermal stability under 185℃,with a small thermal shrinkage of 1%.Meanwhile,the LDPE and Al_(2)O_(3)layers can improve the electrolyte wettability and electrolyte uptake(407.23%).The multilayer ASPESA separator delivers an excellent cycle performance in LiFePO_(4)||Li cells with a discharge capacity of 144.5 mAh g^(-1)after 900 cycles,with a high-capacity retention of 98.9%(compared to the 5th cycle).Therefore,the multilayer ASPESA separator has great utilization potential as a high-safety separator in LIBs.

Metasurface array for single-shot spectroscopic ellipsometry

Spectroscopic ellipsometry is a potent method that is widely adopted for the measurement of thin film thickness and refractive index.Most conventional ellipsometers utilize mechanically rotating polarizers and grating-based spectrometers for spectropolarimetric detection.Here,we demonstrated a compact metasurface array-based spectroscopic ellipsometry system that allows single-shot spectropolarimetric detection and accurate determination of thin film properties without any mechanical movement.The silicon-based metasurface array with a highly anisotropic and diverse spectral response is combined with iterative optimization to reconstruct the full Stokes polarization spectrum of the light reflected by the thin film with high fidelity.Subsequently,the film thickness and refractive index can be determined by fitting the measurement results to a proper material model with high accuracy.Our approach opens up a new pathway towards a compact and robust spectroscopic ellipsometry system for the high throughput measurement of thin film properties.

Natural logarithm wavelength modulation spectroscopy

Natural logarithm wavelength modulation spectroscopy(ln-WMS) is demonstrated in this Letter. Unlike the conventional wavelength modulation spectroscopy(WMS)-2 f technique, it is a linear method even for large absorbance, which is the core advantage of ln-WMS. The treating method used in ln-WMS is to take the natural logarithm of the transmitted intensity. In order to determine the proper demodulation phase, the η-seeking algorithm is introduced, which minimizes the absolute value of the first harmonic within the non-absorbing region. Subsequently, the second harmonic of the absorption signal is extracted by setting the demodulating phase as 2η. To illustrate the validity of ln-WMS, it was applied to water vapor experimentally. The result shows that even if the absorbance(base-e) is between 1.60 and 6.26, the linearity between ln-WMS-2 f and volume fraction is still established. For comparison, measurement with conventional WMS-2 f was also done, whose response no longer kept linearity. The η values retrieved in continuous measurements and the residuals were shown so as to evaluate the performance of the η-seeking algorithm. Time consumed by this algorithm was roughly 0.28 s per measurement. As an alternative WMS strategy, ln-WMS has a wide range of potential applications, especially where the absorbance is large or varies over a wide area.

Computational spectropolarimetry with a tunable liquid crystal metasurface

While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging from imaging to telecommunication.However,the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements,leading to excessive system complexity.Here,we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal metasurface.The tunable metasurface,which acts as an encoder of the vectorial light field,is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features,thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high fidelity.The concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size,weight,cost,and complexity.

The Update of Fetal Growth Restriction Associated with Biomarkers

Fetal growth restriction(FGR)has a prevalence of about 10%worldwide and is associated with an increased risk of perinatal mortality and morbidity.FGR is commonly caused by placental insufficiency and can begin early(<32 weeks)or in late(≥32 weeks)gestational age.A false positive antenatal diagnosis may lead to unnecessary monitoring and interventions,as well as cause maternal anxiety.Whereas a false negative diagnosis exposes the fetus to an increased risk of stillbirth and renders the pregnancy ineligible from the appropriate care and potential treatments.The clinical management of FGR pregnancies faces a complex challenge of deciding on the optimal timing of delivery as currently the main solution is to deliver the baby early,but iatrogenic preterm delivery of infants is associated with adverse short-and long-term outcomes.Early and accurate diagnosis of FGR could aid in better stratification of clinical management,and the development and implementation of treatment options,ultimately benefiting clinical care and potentially improving both short-and long-term health outcomes.The aim of this review is to present the new insights on biomarkers of placenta insufficiency,including their current and potential value of biomarkers in the prediction and prevention for FGR,and highlight the association between biomarkers and adverse outcomes in utero to explore the specific mechanism of impaired fetal growth that establish the basis for disease later in life.