Garnet-type Solid-state Electrolyte Li7La3Zr2O12: Crystal Structure,Element Doping and Interface Strategies for Solid-state Lithium Batteries

The continuous development of solid-state electrolytes(SSEs) has stimulated immense progress in the development of all-solid-state batteries(ASSBs). Particularly, garnet-typed SSEs in formula of Li₇La₃Zr₂O₁₂(LLZO) are under intensive investigation to exploit their advantage in high lithium ions conductivity(>1 mS/cm), wide electrochemical window(>5 V), and good chemical electrochemical stability for lithium, which are critical factors to ensure a stable, and high performance ASSBs. This review will focus on the challenges related to LLZOs-based electrolyte, and update the recent developments in structural design of LLZOs, which are discussed in three major sections:(i) crystal structure and the lithium-ion transport mechanism of LLZO; (ii) single-site and multi-site doping of Li sites, La sites and Zr sites to enhance Li ions conductivity(LIC) and stability of LLZO; (iii) interface strategies between electrodes and LLZO to decrease interface area-specific resistance(ASR).     

C4Sm-4相对稳定性的从头算研究

从五十年代至今，对用通式C；；0：－…＝3，45，6n表征的氧碳化合物（OXOCCbollS）已进行了大显的理论和实验研究，认为它们是一类新的芳香化合物山．用硫、硒等取代氧的类似化合物（一般称为类氧碳化合物或假氧碳化合物，ps。11。10－OX。。CCI．b0118）的研究也有许多报导［     

Theoretical study on the bromomethane-water 1:2 complexes

Bromomethane-water 1:2 complexes have been theoretically studied to reveal the role of hydrogen bond and halogen bond in the formation of different aggregations. Four stable structures exist on the potential energy surface of the CH3Br(H2O)2 complex. The bromine atom acts mainly as proton acceptor in the four studied structures. It is also capable of participating in the formation of the halogen bond. The properties and characteristics of the hydrogen bond and the halogen bond are investigated employing several different quantum chemical analysis methods. Cooperative effects for the pure hydrogen bonds or the mixed hydrogen bonds with halogen bonds and the possibility of describing cooperative effects in terms of the topological analysis of the electronic density or the charge-transfer stabilization energy are discussed in detail. An atoms-in-molecules study of the hydrogen bond or the halogen bond in the bromomethane-water 1:2 complexes suggests that the electronic density topology of the hydrogen bond or the halogen bond is insensitive to the cooperative effect. The charge-transfer stabilization energy is proportional to the cooperative effect, which indicates the donor-acceptor electron density transfer to be mainly responsible for the trimer nonadditive effect.     

Phase transformation in spodumene–diopside glass

In situ developments of platelike spodumene–diopside grains were obtained by controlled devitrification of the complex system Li₂O–CaO–MgO–Al₂O₃–SiO₂ glass. The crystallization mechanisms of spodumene–diopside glass were measured by isothermal and non-isothermal processes using classical and differential thermal analysis techniques. The Avrami constant n was 2.0–2.1, indicating two-dimensional crystal growth and platelike grains. The crystalline phases precipitated first were high-quartz_s.s., then transformed to β-spodumene and diopside. The Flexural strength, fracture toughness and thermal shock resistance (in 20°C water) increased from 145 MPa, 1.3 MPa m^1/2, 800°C (pure spodumene) to 197 MPa, 2.9 MPa m^1/2 and 920°C (spodumene–diopside) with low thermal expansion coefficient (from 3∼9·10^–7 to 11.8·10^–7 K^–1). This mean in situ developments of platelike spodumene–diopside grains reinforced the low thermal expansion coefficient glass-ceramics.     

甲基丙烯酸镁增强氢化丁腈橡胶的结构与形态和性能

用不同份量的甲基丙烯酸镁(MgMA)作增强剂,过氧化二异丙苯(DCP)作硫化剂,通过混炼和硫化过程的原位聚合制备了氢化丁腈橡胶/聚甲基丙烯酸镁(HNBR/PMgMA)纳米复合材料,用XRD、FTIR1、3C-NMR、SEM、TEM、DMA和交联密度分析等方法研究了其结构、形态和性能,并阐述了MgMA改性HNBR的相关机理.结果表明,MgMA在混炼过程中粒径明显变小,部分达到纳米级.硫化过程中发生原位自由基聚合,并部分接枝到HNBR分子链上,HNBR硫化胶和PMgMA有可能形成接枝互穿聚合物网络(接枝IPN).随着MgMA用量的增加,纳米复合材料硫化胶的定伸应力、拉伸强度、扯断伸长率、撕裂强度和热氧老化性能逐渐提高.当MgMA含量为30份时,体系的拉伸强度和扯断伸长率分别为38.5MPa和545%,并具有优异的热空气老化性能.MgMA能明显增加HNBR复合材料的储能模量,并降低其损耗因子.随着MgMA用量的增加,纳米复合材料硫化胶的总交联密度(Ve)和离子键交联密度(Ve2)增加,而共价键交联密度(Ve1)下降,表明离子键对HNBR/PMgMA纳米复合材料的力学性能起重要作用.     

基于虚拟仪器和可调谐激光技术的光纤光栅传感系统

提出了一种新颖的基于虚拟仪器(VI)和可调谐激光技术的光纤光栅(FBG)传感系统,利用可调谐激光对由光纤光栅组成的传感器阵列进行波长扫描,实现了多根光栅的复用准静态解调,并结合抖动技术和反馈环结构,使得探测信号在每一根传感光栅中心波长处过零,以提高系统在测定波长偏移时的分辨力。当反馈环工作在闭环状态下时,该系统还可对单根光栅实现动态跟踪锁定,实现单根光栅的动态解调。该传感系统的数据采集采用虚拟仪器技术,通过多通道同时输入输出实现了在线实时解调。实验采用了4根光栅组成传感阵列,获得了静态多根光栅小于1με和单根光栅动态频率10 Hz时3.3 n/εHz的解调分辨力,动态应变范围在850με。     

相对论赝势的从头计算法研究铀酰离子电子结构

用相对论赝势的从头算法研究了铀酰离子的几何构型和电子结构.得到了与实验数据较一致的键长、键角和IR振动频率.铀氧间以U5f与O2p相互作用为主,U6d与O2p间的键合较小;同时,U6p、U7s、U6d和Usd杂化轨道与O2s间也有强的相互作用.不同自旋多重度时对铀酰离子总能量计算结果表明,UO22+的基态为1∑g+的可能性更大.     

Density Functional Theory Study on Hydrogen Bonding Interaction of Catechin-(H2O)n

Density functional theory B3LYP method with 6‐31G* basis set has been used to optimize the geometries of the catechin, water and catechin‐(H₂O)_n complexes. The vibrational frequencies have been studied at the same level to analyze these complexes. Six and eleven stable structures for the catechin‐H₂O and catechin‐(H₂O)₂ have been found, respectively. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the systems. The interaction energies of all the complexes corrected by basis set superposition error, are from ?13.27 to ?83.56 kJ/mol. All calculations also indicate that there are strong hydrogen‐bonding interactions in catechin‐water complexes. The strong hydrogen‐bonding contributes to the interaction energies dominantly. The O–H stretching motions in all the complexes are red‐shifted relative to that of the monomer.     

2D and 3D Porphyrinic Covalent Organic Frameworks: The Influence of Dimensionality on Functionality

The construction of 2D and 3D covalent organic frameworks (COFs) from functional moieties for desired properties has gained much attention. However, the influence of COFs dimensionality on their functionalities, which can further assist in COF design, has never been explored. Now, by selecting designed precursors and topology diagrams, 2D and 3D porphyrinic COFs (2D‐PdPor‐COF and 3D‐PdPor‐COF) are synthesized. By model building and Rietveld refinement of powder X‐ray diffraction, 2D‐PdPor‐COF crystallizes as 2D sheets while 3D‐PdPor‐COF adopts a five‐fold interpenetrated pts topology. Interestingly, compared with 2D‐PdPor‐COF, 3D‐PdPor‐COF showed interesting properties, including 1) higher CO₂ adsorption capacity; 2) better photocatalytic performance; and 3) size‐selective photocatalysis. Based on this study, we believe that with the incorporation of functional moieties, the dimensionality of COFs can definitely influence their functionalities.