废旧锂离子电池选择性提锂

新能源汽车行业的蓬勃发展不仅使锂离子电池需求量激增,大批锂离子电池在达到一定循环次数后也会因无法继续使用而报废。目前研究者们已经对废旧锂离子电池中有价金属的提取方法进行了许多研究,但回收过程中重点关注的对象是钴和镍,锂作为锂离子电池中的主要成分没有给予足够的重视。随着锂资源供需关系的日趋紧张,近年来通过将废旧锂离子电池中的锂优先选择性提取以提高其回收效率的研究不断增多。基于此,本文系统梳理了从不同正极材料(如钴酸锂、锰酸锂、镍钴锰酸锂和磷酸铁锂)中选择性提锂的方法,包括高温转型、选择性浸出、机械化学及电化学法,为后续有关退役锂离子电池选择性提锂的研究及产业实践提供参考。     

基于高温化学转化的废旧锂离子电池资源化技术

鉴于废旧锂离子电池的环境危害性和资源化价值的双重属性,对其进行无害化处理并对其中的有价资源进行回收再利用具有十分重要的意义。目前电池资源化技术主要通过高温或常温条件下的化学转化实现。高温条件下,废旧锂离子电池中有价元素化学转化速率快、回收流程短、物料适应性强,易于实现工业应用,相关技术成为废旧锂离子电池资源化研究热点之一。本文基于物相化学转化方式的差异,系统分析了高温化学还原、熔盐化学焙烧以及短程材料再生等方法的物理化学机理、技术特征及研究现状,并对比了不同技术的优势和存在的问题。在此基础上,提出今后高温化学转化方法实现废旧锂离子电池资源化研究中需要考虑材料的短程清洁循环再生、深入研究其化学转化机理。基于绿色化学原理的工艺设计开发出低能耗、环境友好的资源化工艺路线,真正实现废旧锂离子电池的绿色处理和循环利用。     

废旧锂离子电池正极材料及电解液的全过程回收及再利用

作为发展势头迅猛的新型储能形式,锂离子电池缓解了能源领域对化石燃料的依赖,同时减轻了日益严峻的环境压力,但是数量巨大的废旧锂离子电池具有危险废弃物和高附加值可用资源的双重属性。因此,通过不同技术手段的创新和组合,实现组成成分日益多样化的废旧锂离子电池的高效回收和再利用具有巨大的挑战和特殊重要的现实意义。本文从预处理工艺出发,详细阐述了放电失活、分类拆解、粉碎筛分、酸浸除杂等一系列过程的技术手段和要求;从原料再生、结构修复以及再制备三个方面探讨了具有代表性的再利用思路,分析了各技术方法的优势和存在的问题。此外,对废旧电解液的无害化处理和回收进行了专题讨论,重点介绍了超临界CO₂萃取工艺。最后,针对现阶段存在的问题提出展望,为后续开展废旧锂离子电池回收的相关研究及工业应用提供参考。     

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。     

氟磷酸盐及正硅酸盐锂离子电池正极材料研究进展

综述了用于锂离子电池的氟磷酸盐和正硅酸盐正极材料的研究现状, 重点对各种材料的结构及合成方法与性能的关系, 特别是对如何改善材料的电化学性能进行了总结和探讨. 展望了这两类锂离子电池正极材料的发展趋势.     

锂离子电池正极材料的晶体结构及电化学性能

正极材料是锂离子电池的重要组成部分。作为提供自由脱嵌锂离子的正极材料,其晶体结构的特点决定了锂离子脱嵌路径方式的不同,并对锂离子电池的电化学性能等产生明显影响。本文根据正极材料的晶体结构和锂离子“脱嵌/嵌入”路径方式的不同,重点讨论了一维隧道结构、二维层状结构和三维框架结构正极材料的晶体结构特点、锂离子“脱嵌/嵌入”路径和其电化学性能之间的关系,主要包括一维隧道结构正极材料LiFePO₄,二维层状结构正极材料LiMO₂(M=Co, Ni, Mn)、Li_1+xV₃O₈和Li₂MSiO₄ (M=Fe, Mn) 以及三维框架结构正极材料LiMn₂O₄和Li₃V₂(PO₄)₃。揭示了目前锂离子电池正极材料的研究现状和存在问题,并对今后的发展方向进行了评述。     

聚阴离子型锂离子电池正极材料研究进展

综述了各种聚阴离子型锂离子电池正极材料的研究现状,重点对各种材料的结构和性能的关系,尤其是聚阴离子在正极材料中的作用,以及改善材料电导率的各种方法及其机理进行了总结和探讨.     

掺杂对钠离子电池正极材料性能影响机制的研究

钠元素在地壳中的丰度是锂元素的1000倍,资源丰富,价格低廉。同时,钠离子电池负极可采用廉价的铝箔替代铜箔,且低温特性更加优异,在能量型、备用型储能场景均具有较好应用前景,因而钠离子电池被认为是下一代大规模储能技术的理想选择之一。然而,相对锂离子而言,钠离子较大的离子半径和质量极大限制了其在电极材料中的可逆脱嵌,导致电池的工作电压和能量密度相对较低。在钠离子电池材料体系中,正极材料的研究尤为需要长足的进步。本文对现有的典型钠离子电池正极材料进行了综述,包括层状金属氧化物、聚阴离子化合物和普鲁士蓝类化合物,并重点分析了掺杂对钠离子电池正极材料性能的影响。通过元素掺杂可提高材料的循环可逆性、增加其可逆容量、提升钠离子扩散动力学性能,能够在一定程度上改变晶格的性质,增强晶格稳定性、电子导电性、钠离子嵌脱动力学性能等。本文总结了掺杂应用在现有材料中获得的成果,并对正极材料未来的研究方向以及发展前景提出了展望。     

不同掺杂元素对无钴高镍正极材料的影响

随着动力电动汽车的需求不断增加,发展低成本、高能量密度的锂离子电池正极材料成为关键。无钴高镍正极材料因其能量密度高、倍率性能好而受到了极大的关注。对于无钴高镍正极材料在循环过程中热稳定性差、容量衰减等问题,研究者们虽通过不同的掺杂元素改善了材料的电化学性能,但对不同掺杂元素的作用机理研究尚浅。本文综述了近年来无钴高镍正极材料掺杂改性方面的研究进展,重点总结了不同掺杂元素对改善材料电化学性能的作用机理。综合分析表明,向无钴高镍正极材料引入掺杂元素,尽管掺杂元素在材料中的主要作用机理不尽相同,但均都提高材料电化学性能,从而改善了无钴高镍材料固有的问题。最后,对无钴高镍正极材料改善策略的发展方向进行了展望,提出了多重改善策略协同应用的可行性方案。     

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。     

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.     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.