基于磷酸铁锂的锂离子动力电池性能

磷酸铁锂（LiFePO4）因其无毒、对环境友好、原材料来源丰富、比容量高、循环性能好、安全性能优异等特点已被公认为突破正极材料制约的新一代安全低成本高容量大功率型动力或储能锂离子电池首选正极材料，已成为我国及世界主要发达国家锂离子动力电池的重点发展方向。     

关于水系锌离子电池中无氧钒基正极材料的综述

水系锌离子电池具有功率密度高、环境友好、安全性高、低成本和锌资源丰富等优点，被认为具有潜力成为下一代电化学储能系统。然而，正极材料较差的电化学性能制约了水系锌离子电池的未来发展。尽管氧化锰、氧化钒、普鲁士蓝类似物、有机材料等多种材料已被广泛研究，设计具有高性能的理想正极材料仍面临着巨大挑战。无氧钒基化合物由于具有高的电导率、大的层间距、低的离子扩散势垒和高的理论比容量，受到越来越多的关注。本文总结了无氧钒基化合物的研究进展，包括电极材料的设计、改善其电化学性能的有效途径以及复杂的储能机制，提出了无氧钒基化合物目前面临的挑战和未来的发展前景，为进一步制备新型高性能钒基正极材料提供指导。     

水系锌离子电池用钒基正极材料的研究进展

水系锌离子电池(aqueous zinc-ion batteries,AZIBs)具有高安全性、低生产成本、锌资源丰富和环境友好等优点,被认为是未来大规模储能系统中极具发展前景的储能装置。目前,AZIBs的研究关键之一在于开发具有稳定结构和高容量的锌离子可脱嵌正极材料。钒基化合物用作AZIBs正极时,表现出可逆容量高和结构丰富可变等特点,受到了广泛的关注和研究。然而,钒基化合物的储锌机理较复杂,不同材料通常表现出各异的电化学性能和储能机理。在本综述中,我们全面地阐述了钒基化合物的储能机制,并探讨了钒基材料在水系锌离子电池中的应用和发展近况,以及它们的性能优化策略。在此基础上,也进一步地展望了水系锌离子电池及其钒基正极材料的发展方向。     

导电高分子-金属氧化物复合材料用作锂离子电池正极材料的研究现状

随着人类社会对能源需求量的增大,高效储能材料的开发备受关注。导电高分子-金属氧化物复合材料具备了作为储能器件正极材料的诸多特质,故成为了相关研究领域的热点方向之一。本文以聚苯胺(PAni)和聚吡咯(PPy)为例,综述了近年来导电高分子-金属氧化物复合材料用作锂离子电池正极材料方面的研究进展。概述了此类材料中各组分如何通过有机/无机协同作用实现材料电化学性能的提升,介绍了此类材料的制备方法,结构特点及常用表征手段,以及材料的电化学性能特征。     

钠离子电池层状过渡金属氧化物正极材料研究进展

钠离子电池层状过渡金属氧化物正极材料具有价格低廉、比容量相对高的特点,是未来大型储能电站等能源转型设施的重要候选者,与锂离子电池在市场中的应用场景互为补充,为能源转型提供了有力支持,钠离子电池以Na+特有的理化性质而具有极大的开发潜力。然而,层状过渡金属氧化物正极材料在充放电过程伴随着钠离子的嵌入、脱出会产生一系列不利于其电化学性能的变化,如过渡金属溶解、结构相转变、相对较低的能量密度和较差的空气稳定性与循环稳定性,因此对正极材料的结构与性能进行优化变得尤为重要。近10年来许多研究学者针对层状正极材料的失效机制进行了结构上的优化,得到了性能相对良好的正极材料,报道了当前层状过渡金属氧化物正极材料的电化学性能失效机制、改性手段的现状,对钠离子层状氧化物正极材料面临的挑战进行了总结,并对未来发展需要解决的关键问题做出了展望。     

动力型锂离子电池富锂三元正极材料研究进展

随着电动汽车、智能电网以及大规模储能领域的快速发展,对作为储能设备的锂离子电池的各项性能指标,如能量密度和功率密度等,提出了更加苛刻的要求。因此,开发稳定性好、比容量高的新型正极材料是进一步提高锂离子电池能量密度的关键。富锂三元正极材料xLi_2MnO_3·(1-x)Li Mn_(1/3)Ni_(1/3)Co_(1/3)O_2(0.1≤x≤0.5)具有工作电压高、比容量高、环境友好等优点,引起了广大科研工作者的高度关注和广泛研究。本文就此类新型富锂三元正极材料的研究进展进行了总结,对该类材料的晶体结构特征以及首次充放电机理、电化学性能的改善等进行了评述,并对其未来的发展方向进行了展望。     

基于磷酸铁锂的锂离子动力电池性能

磷酸铁锂(LiFePO4)因其无毒、对环境友好、原材料来源丰富、比容量高、循环性能好、安全性能优异等特点已被公认为突破正极材料制约的新一代安全低成本高容量大功率型动力或储能锂离子电池首选正极材料,已成为我国及世界主要发达国家锂离子动力电池的重点发展方向[1,2].     

锂离子电池纳米正极材料

综述了锂离子电池纳米正极材料的研究进展,阐述了这种材料用于锂离子电池的优势和存在的问题,把纳米正极材料分为过渡金属嵌锂化合物、金属氧化物和金属硫化物和其它纳米正极材料。归纳了不同纳米正极材料的主要制备方法,探讨了材料的制备方法与其结构、形貌和电化学性能之间的关系,展望了纳米正极材料用于锂离子电池的未来前景。     

钒系磷酸盐锂离子电池正极材料

商业化锂离子电池以锂过渡金属氧化物作正极材料,由于安全性等问题限制了其更广泛的应用。在已经研究和开发的众多新型锂离子电池正极材料中,钒系磷酸盐由于具有较高的对锂电位和理论比容量而成为研究热点。本文综述了各种钒系磷酸盐类锂离子电池正极材料的研究现状,重点对各种材料的结构、制备方法和电化学性能进行了总结,并对改善材料综合性能的方法和机理进行了探讨。     

基于P2-Na_(0.7)CoO_2微球的高性能钠离子电池正极材料

<正>钠具有资源丰富、价格低廉、环境友好以及与锂相似的电化学性质等特点。相比于锂离子电池,钠离子电池更适合应用于大规模储能,近年来得到了研究人员的广泛关注~(1,2)。目前,所研究的钠离子电池正极材料主要有层状金属氧化物、隧道型金属氧化物、普鲁士蓝类化合物和聚阴离子型化合物等。其中,层状过渡金属氧化物正极材料由于体系丰富、电化学活性     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.