Chelate Effects in Glyme/Lithium Bis(trifluoromethanesulfonyl)amide Solvate Ionic Liquids, Part 2: Importance of Solvate-Structure Stability for Electrolytes of Lithium Batteries

Zhang, Ce,Yamazaki, Azusa,Murai, Junichi,Park, Jun-Woo,Mandai, Toshihiko,Ueno, Kazuhide,Dokko, Kaoru,Watanabe, Masayoshi American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.31

<P>Highly concentrated, molten mixtures of lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]) and ether solvents (tetrahydrofuran (THF), monoglyme (G1), diglyme (G2), and triglyme (G3)) were investigated as electrolytes for Li batteries. To compare the electrochemical reactions in the electrolytes with different solvents, the ratio of ether–oxygen atoms and Li<SUP>+</SUP> ([O]/[Li]) in the electrolytes was fixed at four. The capacity of a Li–LiCoO<SUB>2</SUB> cell with [Li(THF)<SUB>4</SUB>][TFSA] dramatically decreased upon charge/discharge cycling, whereas [Li(G3)<SUB>1</SUB>][TFSA] allowed the cell to have a stable charge–discharge cycles and a Coulombic efficiency of greater than 99% over 100 cycles. Corrosion of the Al current collector of the cathode was also affected by the composition of the electrolytes. Persistent Al corrosion took place in [Li(THF)<SUB>4</SUB>][TFSA] and [Li(G1)<SUB>2</SUB>][TFSA], which contain shorter ethers, but the corrosion was effectively suppressed in [Li(G3)<SUB>1</SUB>][TFSA]. Furthermore, lithium polysulfides, which are formed as discharge intermediates at the sulfur cathode of the Li–S cell, were much less soluble in electrolytes with longer ethers. Therefore, a higher Coulombic efficiency and more stable cycle ability were achieved in Li–S cells with [Li(G3)<SUB>1</SUB>][TFSA]. All the electrochemical properties in the batteries were dominated by the presence or absence of uncoordinating solvents in the concentrated electrolytes. This paper demonstrates that the structural stability of [Li(glyme or THF)<SUB><I>x</I></SUB>]<SUP>+</SUP> cations in electrolytes plays an important role in the performance of Li batteries.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-31/jp504099q/production/images/medium/jp-2014-04099q_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp504099q'>ACS Electronic Supporting Info</A></P>

Investigation of the Neuropathic Pain Caused by Syringomyelia Associated with Chiari I Malformation

Toshitaka Seki,Shuji Hamauchi,Masayoshi Yamazaki,Kazutoshi Hida,Shunsuke Yano,Kiyohiro Houkin 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4

Study Design: Retrospective cohort study. Purpose: To investigate the correlation between the syrinx morphology and neuropathic pain caused by syringomyelia associated with Chiari I malformation. Overview of Literature: Neuropathic pain caused by syringomyelia is refractory and markedly impairs the patient. Methods: We examined 24 patients with neuropathic pain caused by syringomyelia associated with Chiari I malformation. We statistically analyzed the illness duration and age at surgery between patients with and without neuropathic pain. Additionally, we classified the morphology of the syringes into deviated (D), enlarged (E), central (C), and bulkhead (B) types using T2-weighted axial imaging. Moreover, we investigated the correlation between syrinx morphology and neuropathic pain. A Mann–Whitney U-test was performed to compare between the presence or absence of neuropathic pain and the presence or absence of type D syringes. Results: The median age at surgery was 27.5 years, and the median illness duration was 24 months. Among the 24 patients, 11 had preoperative neuropathic pain, one of which was free of neuropathic pain during the final follow-up period. Among patients with neuropathic pain, the syringes’ preoperative morphology was type D in nine patients and types E and C in one patient each. No patient exhibited type B morphology. Among patients without neuropathic pain, the preoperative morphology of the syringes was type D in three patients, type E in seven patients, and types C and B in two patients each. For types D and E, a correlation between neuropathic pain and syrinx morphology was observed. Moreover, type D was associated with significant neuropathic pain in both preoperative and postoperative states. Conclusions: This study showed a correlation between the morphological features of the syringes and the occurrence of neuropathic pain in patients with syringomyelia associated with Chiari I malformation.

Anionic Effects on Solvate Ionic Liquid Electrolytes in Rechargeable Lithium–Sulfur Batteries

Ueno, Kazuhide,Park, Jun-Woo,Yamazaki, Azusa,Mandai, Toshihiko,Tachikawa, Naoki,Dokko, Kaoru,Watanabe, Masayoshi American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.40

<P>A series of equimolar mixtures of Li salts (LiX) and glymes (triglyme (G3) and tetraglyme (G4)), [Li(glyme)]X with different anions (X: [N(SO<SUB>2</SUB>C<SUB>2</SUB>F<SUB>5</SUB>)<SUB>2</SUB>] = [BETI]; [N(SO<SUB>2</SUB>CF<SUB>3</SUB>)<SUB>2</SUB>] = [TFSA]; [CF<SUB>3</SUB>SO<SUB>3</SUB>] = [OTf]; BF<SUB>4</SUB>; NO<SUB>3</SUB>), were used as electrolytes to study the anionic effects of [Li(glyme)]X on the performance of lithium–sulfur (Li–S) batteries. The dissolution of lithium polysulfides (Li<SUB>2</SUB>S<SUB><I>m</I></SUB>), which are discharge products of elemental sulfur, was significantly suppressed in the solvate ionic liquid (IL) electrolytes, as seen in [Li(G4)][BETI] and [Li(glyme)][TFSA], wherein all of the glymes participated in the formation of the complex cation [Li(glyme)]<SUP>+</SUP>. It was found that NO<SUB>3</SUB> anions were irreversibly reduced at the composite cathode during discharge and BF<SUB>4</SUB> anions formed unexpected byproducts through a chemical reaction with the polysulfide anions. Successful charge/discharge of Li–S cell could not be performed in [Li(glyme)]X in the presence of these anions because of the undesired side reactions. The solvate IL [Li(G4)][BETI] was found to be electrochemically stable in the Li–S cell and allowed a stable operation with a capacity of 600–700 mAh·g<SUP>–1</SUP> and a Coulombic efficiency of 98.5% over 100 cycles, similar to that achieved by [Li(glyme)][TFSA]. In contrast, the Li–S cell with a concentrated electrolyte solution, [Li(G3)][OTf], showed a much lower capacity and Coulombic efficiency.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-40/jp407158y/production/images/medium/jp-2013-07158y_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp407158y'>ACS Electronic Supporting Info</A></P>

Solvate Ionic Liquid Electrolyte for Li–S Batteries

Dokko, Kaoru,Tachikawa, Naoki,Yamauchi, Kento,Tsuchiya, Mizuho,Yamazaki, Azusa,Takashima, Eriko,Park, Jun-Woo,Ueno, Kazuhide,Seki, Shiro,Serizawa, Nobuyuki,Watanabe, Masayoshi The Electrochemical Society 2013 Journal of the Electrochemical Society Vol.160 No.8

<P>Innovation in the design of electrolyte materials is crucial for realizing next-generation electrochemical energy storage devices such as Li–S batteries. The theoretical capacity of the S cathode is 10 times higher than that of conventional cathode materials used in current Li–ion batteries. However, Li–S batteries suffer from the dissolution of lithium polysulfides, which are formed by the redox reaction at the S cathode. Herein, we present simple solvate ionic liquids, glyme–Li salt molten complexes, as excellent electrolyte candidates because they greatly suppress the dissolution of lithium polysulfides. The molten complexes do not readily dissolve other ionic solutes, which leads to the stable operation of the Li–S battery over more than 400 cycles with discharge capacities higher than 700 mAh g-sulfur<SUP>−1</SUP> and with coulombic efficiencies higher than 98% throughout the cycles. Such high performance has not been realized to the best of our knowledge. Furthermore, the addition of a nonflammable fluorinated solvent, which does not break the solvate structure of the glyme–Li salt molten complexes, greatly enhances the power density of the Li–S battery. The strategic design of electrolyte properties provides opportunities for the development of new electrochemical devices with many different electrode materials.</P>