Effect of Cation Structure of Ionic Liquids on Anode Properties of Si Electrodes for LIB

Ionic liquids consisted of 1-((2-methoxyethoxy)methyl)-1-methylpiperidinium (PP1MEM) or 1-hexyl-1-methylpiperidinium (PP16) and bis(trifluoromethanesulfonyl)amide (TFSA) were applied to an electrolyte for Li-ion battery. The effect of their cation structure on anode properties of Si electrodes were investigated through the use of thick film prepared by gas-deposition without any binder and conductive additive. The Si electrode in PP1MEM-TFSA exhibited an initial reversible capacity of 2670 mA h g−1, which is larger than that in PP16-TFSA by ca. 900 mA h g−1. Moreover, a comparatively high capacity of 1150 mA h g−1 at a high current density of 4200 mA g−1 is achieved in PP1MEM-TFSA whereas the Si electrode in PP16-TFSA showed the capacity of only 210 mA h g−1. Raman analysis and electrochemical impedance measurements revealed that PP1MEM cation played a role reducing the interaction between Li ion and TFSA anions, and that Li-ion transfer at the electrode−electrolyte interface in PP1MEM-TFSA was remarkably improved compared with PP16-TFSA. These results indicate that the excellent performances obtained in PP1MEM-TFSA originate from a smooth Li-insertion into Si electrode. It was suggested that introduction of ether functional group into cation is valid to enhance the electrode performance

Influence of the structure of the anion in an ionic liquid electrolyte on the electrochemical performance of a silicon negative electrode for a lithium-ion battery

We investigated the influence of the anions in ionic liquid electrolytes on the electrochemical performance of a silicon (Si) negative electrode for a lithium-ion battery. While the electrode exhibited poor cycle stability in tetrafluoroborate-based and propylene carbonate-based electrolytes, better cycle performance was achieved in bis(fluorosulfonyl)amide (FSA–)- and bis(trifluoromethanesulfonyl)amide (TFSA–)-based electrolytes, in which the discharge capacity of a Si electrode was more than 1000 mA h g–1 at the 100th cycle. It is considered that a surface film derived from FSA–- and TFSA–-based electrolytes effectively suppressed continuous decomposition of the electrolyte. In a capacity limitation test, a discharge capacity of 1000 mA h g–1 was maintained even after about the 1600th cycle in the FSA–-based electrolyte, which corresponds to a cycle life almost twice as long as that in TFSA–-based electrolyte. This result should be explained by the high structural stability of FSA–-derived surface film. In addition, better rate capability with a discharge capacity of 700 mA h g–1 was obtained at a high current rate of 6 C (21 A g–1) in FSA–-based electrolyte, which was 7-fold higher than that in TFSA–-based electrolyte. These results clarified that FSA–-based ionic liquid electrolyte is the most promising candidate for Si-based negative electrodes

A case of type B aortic dissection in 6 days postpartum

今回我々は産褥6日目にStanford B型大動脈解離を発症した1例を経験したので若干の文献的考察を加えて報告する。症例は42歳、4経妊3経産、尿路結石の既往歴あり、Marfan症候群の家族歴なし。第4子妊娠管理中の血圧は100-130/50-70mmHg であった。妊娠40週3日に自然陣痛発来し、3370g の児をApgar score 8点で経腟分娩した。産褥6日目就寝中に突然腰背部痛をきたし救急車で前医受診。腎結石を疑い、当院泌尿器科受診したが水腎症を認めず、当科紹介受診。造影CT でStanford B型大動脈解離と診断、保存的加療を行い、20日後退院した。Marfan 症候群合併妊婦は妊娠中、産褥期に大動脈解離の発症リスクが高いことが知られている。しかし、本症例のような大動脈解離発症リスクを持たない妊婦も、妊娠中・産褥期の腰背部痛の原因として大動脈解離を鑑別診断することは必要である。雑誌掲載論

Synthesis of Ionic Liquids Equipped with 2‑Methoxy­ethoxy­methyl/Methoxy­methyl Groups Using a Simple Microreactor System

A simple microreactor system has been utilized for the continuous flow synthesis of novel ionic liquids having a (2-meth­oxy­ethoxy)­methyl or methoxy­methyl substituent. Conversion rates of <i>N</i>-bases and tributylphosphine in the microreactor system are faster than those in the batch system because of less diffusion distance in the tube reactor. This method allows us to prepare ionic liquids in efficient yields with high purity