In the search for novel anode materials for lithium-ion batteries (LIBs), organic electrode materials have recently attracted substantial attention and seem to be the next preferred candidates for use as high-performance anode materials in rechargeable LIBs due to their low cost, high theoretical capacity, structural diversity, environmental friendliness, and facile synthesis. Up to now, the electrochemical properties of numerous organic compounds with different functional groups (carbonyl, azo, sulfur, imine, etc.) have been thoroughly explored as anode materials for LIBs, dividing organic anode materials into four main classes: organic carbonyl compounds, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and organic compounds with nitrogen-containing groups. In this review, an overview of the recent progress in organic anodes is provided. The electrochemical performances of different organic anode materials are compared, revealing the advantages and disadvantages of each class of organic materials in both research and commercial applications. Afterward, the practical applications of some organic anode materials in full cells of LIBs are provided. Finally, some techniques to address significant issues, such as poor electronic conductivity, low discharge voltage, and undesired dissolution of active organic anode material into typical organic electrolytes, are discussed. This paper will guide the study of more efficient organic compounds that can be employed as high-performance anode materials in LIBs.
Increasing the interlaboratory reproducibility of gas chromatographic retention indices requires avoiding measurements distorted by overloading effects. Several criteria of evaluating the limits of the mass overloading of gas chromatographic systems are compared and reconsidered. The criteria mostly appropriate for practical purposes are based on (i) the dependences of factors of peak broadening (ratio of peak height and its width) vs. amount of analyte injected into the chromatographic column and (ii) the dependence of parameters characterizing the peak distortion (asymmetry factor) vs. the amount of analyte. Both these criteria provide mutually comparable evaluations of the overloading limits for analytes of different polarity. At the same time, the dependence of retention indices vs. amounts of analyte injected in the chromatographic column cannot be recommended for overloading control, because the parameters of the corresponding linear regressions indicate temperature dependence. The interpretation of certain gas chromatographic anomalies requires the correct evaluation of overloading limits. For example, the unusual temperature dependence of retention indices of polar analytes on non-polar stationary phases and the dependence of retention indices on ratio of amounts of target analytes and reference compounds.
Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования «Санкт-Петербургский государственный университет », институт химии 198504, С-Петербург, Университетский пр. 26 izenkevich@mail15.com Поступила в редакцию 14 января 2014 г., после доработки -15 мая 2014 г.На примере соединений различной химической природы (диметилформамид, диметилсульфоксид и некоторые другие) выполнена экспериментальная проверка аномальной температурной зависимости индексов удерживания RI(Т) по ляр ных аналитов на неполярной неподвижной фазе (BPX-1). Суть этой аномалии, впервые выявленной в 1990 -начале 2000 гг., заключается в непостоянстве знака темпера тур ных коэф фи ци ентов b = dRI/dT, что приводит к появлению миниму мов RI. Более подробное рассмотрение зависимости RI(Т) показало, что такие ано малии не связаны с перегрузкой хроматографических колонок, а их вид, как установлено впервые, зависит от до зи руемых коли че ств аналитов. Например, при увеличении количества диметилформамида в хроматографической зоне от 0.6 до 17 мкг зависимость RI(Т) трансформируется из нелинейной возрастающей к зависимости с минимумом и, далее, к линейно убывающей. Показано, что одной из причин наблюдаемых аномалий является увеличение асимметрии хроматографических пиков полярных аналитов на неполярных фазах при уменьшении температуры.Ключевые слова: газовая хроматография, полярные аналиты, неполярные не подвижные фазы, индексы удерживания, аномальная температурная зависимость.Зенкевич Игорь Георгиевич -д.х.н., профессор кафедры органической химии, зав. лабораторией газо вой хроматографии химического факультета СПбГУ.Область научных интересов: хроматографические методы анализа, иден тификация неизвестных веществ.Автор/соавтор более 550 публикаций.Павловский Александр Александрович -студент 2го курса магистратуры хими ческого факультета СПбГУ. Тема работы связана с характеристикой температурной за висимости газохроматографических индексов удер живания.Первая публикация.
Research on the regeneration of cathode materials of spent lithium-ion batteries for resource reclamation and environmental protection is attracting more and more attention today. However, the majority of studies on recycling lithium-ion batteries (LIBs) placed the emphasis only on recovering target metals, such as Co, Ni, and Li, from the cathode materials, or how to recycle spent LIBs by conventional means. Effective reclamation strategies (e.g., pyrometallurgical technologies, hydrometallurgy techniques, and biological strategies) have been used in research on recycling used LIBs. Nevertheless, none of the existing reviews of regenerating cathode materials from waste LIBs elucidated the strategies to regenerate lithium nickel manganese cobalt oxide (NCM or LiNixCoyMnzO2) cathode materials directly from spent LIBs containing other than NCM cathodes but, at the same time, frequently used commercial cathode materials such as LiCoO2 (LCO), LiFePO4 (LFP), LiMn2O4 (LMO), etc. or from spent mixed cathode materials. This review showcases the strategies and techniques for regenerating LiNixCoyMnzO2 cathode active materials directly from some commonly used and different types of mixed-cathode materials. The article summarizes the various technologies and processes of regenerating LiNixCoyMnzO2 cathode active materials directly from some individual cathode materials and the mixed-cathode scraps of spent LIBs without their preliminary separation. In the meantime, the economic benefits and diverse synthetic routes of regenerating LiNixCoyMnzO2 cathode materials reported in the literature are analyzed systematically. This minireview can lay guidance and a theoretical basis for restoring LiNixCoyMnzO2 cathode materials.
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