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Magnesium bis(trifluoromethanesulfonyl)amide complexes with triglyme and asymmetric homologues: phase behavior, coordination structures and melting point reduction
Get PDFThe phase behavior of binary mixtures of triglyme (G3) and Mg[TFSA]2 (TFSA: bis(trifluoromethanesulfonyl)amide) was investigated, towards development of a Mg2+-based room-temperature solvate ionic liquid (SIL) electrolyte. In a 1:1 molar ratio, G3 and Mg[TFSA]2 form a thermally stable complex (decomposition temperature, Td: 240 °C) with a melting point (Tm) of 70 °C, which is considerably lower than that of the analogous tetraglyme (G4) system (137 °C). X-ray crystallography of a single crystal of [Mg(G3)][TFSA]2 revealed that a single Mg2+ cation is coordinated by a single, distorted, tetradentate G3 molecule from one side, and two monodentate [TFSA]− anions, with transoid conformation, from the reverse side to form an ion pair. Raman spectra of [Mg(G3)][TFSA]2 in the molten state revealed the presence of different coordination structures, as the liquid exhibits changes in the vibrational modes corresponding to G3 and the [TFSA]− anion compared to those observed for the solid. Investigation of the ion pair stabilization energies by DFT calculation suggests that higher stability cation complexes and ion pairs co-exist in the molten state than those observed in the crystalline state. These results imply that the coordination structures of the ion pairs play a key role in providing SILs with low Tm. To decrease the Tm further, several asymmetric homologues of G3, which have higher conformational flexibility than G3, were investigated. Notably, the 1:1 mixture of Mg[TFSA]2 with G3Bu (where one of the terminal methyl groups of G3 is substituted for a butyl group) formed a thermally stable complex (Td: 251 °C) without any distinct Tm and showed reasonable ionic conductivity at room-temperature, indicating partial dissociation of ions. In this electrolyte, which showed high oxidative stability, quasi-reversible Mg deposition/dissolution was achieved, indicating that Mg2+-based room-temperature SILs can be utilized as a new class of Mg electrolyte
Solvent Activity in Electrolyte Solutions Controls Electrochemical Reactions in Li-Ion and Li-Sulfur Batteries
Get PDFSolvent-ion and ion-ion interactions have significant effects on the physicochemical properties of electrolyte solutions for lithium batteries. The solvation structure of Li+ and formation of ion pairs in electrolyte solutions composed of triglyme (G3) and a hydrofluoroether (HFE) containing 1 mol dm‒3 Li[TFSA] (TFSA: bis(trifluoromethanesulfonyl)amide) were analyzed using pulsed-field gradient spinecho (PGSE) NMR and Raman spectroscopy. It was found that Li+ is preferentially solvated by G3 and forms a [Li(G3)]+ complex cation in the electrolytes. The HFE scarcely participates in the solvation because of low donor ability and relatively low permittivity. The dissociativity of Li[TFSA] decreased as the molar ratio of G3/Li[TFSA] in the solution decreased. The activity of G3 in the electrolyte diminishes negligibly as the molar ratio approaches unity because G3 is involved in 1:1 complexation with Li+ ions. The negligible activity of G3 in the electrolyte solutions has significant effects on the electrochemical reactions in lithium batteries. As the activity of G3 diminished, the oxidative stability of the electrolyte was enhanced. The corrosion rate of the Al current collector of the positive electrode was suppressed as the activity of G3 diminished. The high oxidative stability and low corrosion rate of Al in the G3/Li[TFSA] = 1 electrolyte enabled the stable operation of 4-V-class lithium batteries. The activity of G3 also has a significant impact on the Li+ ion intercalation reaction of the graphite electrode. The desolvation of Li+ occurs at the interface of graphite and the electrolyte when the activity of G3 in the electrolyte is significantly low, while the co-intercalation of Li+ and G3 takes place in an electrolyte containing excess G3. The activity of G3 influenced the electrochemical reaction process of elemental sulfur in a Li-S battery. The solubility of lithium polysulfides, which are reaction intermediates of the sulfur electrode, decreased as the activity of G3 in the electrolyte decreased. In the G3/Li[TFSA] = 1 electrolyte, the solubility of Li2Sm is very low, and highly efficient charge/discharge of the Li-S battery is possible without severe side reactions
<Article>Revision of Accounting Standards for Public Interest Corporations in 2025: Consideration of “Disclosure of Easy-to-Understand Financial Information”
Get PDFStudy on explicit solutions to embedding problems
Get PDF横浜国立大学博士（理学）この学位論文の全文は、中央図書館で平日17時までに申請することで閲覧が可能です。The full text of this thesis is available for viewing at the Central Library upon request by 5:00 p.m. on weekdays
界面活性剤の水生甲殻類への毒性に関する研究―水質と生分解が与える影響への界面活性からのアプローチ―
Get PDF横浜国立大学博士（工学）この学位論文の全文は、中央図書館で平日17時までに申請することで閲覧が可能です。The full text of this thesis is available for viewing at the Central Library upon request by 5:00 p.m. on weekdays
反射法地震探査データから推定される室戸沖南海トラフにおける浅部スロー地震の発生メカニズム
Get PDF横浜国立大学博士（理学）Dissertation title from dissertation abstract: Mechanism of shallow slow earthquakes in Nankai Trough offshore Muroto inferred from seismic reflection dat
<Management Lecture Series>Series Seven: Case Study as a Research Strategy: How to Analyze the Data
No full textUltrastrong Light–Matter Coupling and its Spectroscopy
Get PDFSqueezing of quantum fluctuation is obtained by ultrastrong coupling even in thermal equilibrium. Fluctuation spectroscopy as been developed rapidly in recent years and is useful for observing the quantum squeezing in equilibrium.近年，様々な物質と共振器の系で，電磁波と物質の超強結合とよばれる状況が報告されている．超強結合自体は，共振器付きの試料さえ用意すれば，吸収スペクトルなどの線形分光法で確認することができるが，超強結合特有の現象の議論においては，仮想光子や反回転項，A2項などの専門用語が頻出する．本稿では，そのような専門用語を解説し，線形分光法だけでもある程度の研究ができること，また，将来的にどのような分光測定法が望まれているのかを紹介する