Details of a Researcher - Serizawa, Nobuyuki

Papers - Serizawa, Nobuyuki

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Electrochemical behavior of silver halogenocomplexes in an amide-type ionic liquid

Serizawa N., Kuwahara S., Katayama Y.

ECS Transactions (ECS Transactions) 98 ( 10 ) 209 - 214 2020

© The Electrochemical Society The electrochemical behavior of halogenocomplexes of Ag was investigated in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) in the presence of the corresponding halogen anion. Silver halides, AgX (X- = Cl-, Br-, and I-) were found to be soluble in BMPTFSA containing 0.5 M BMPX by forming [AgX3]2-. The cathodic reduction of [AgX3]2- to metallic Ag was possible within the electrochemical window of BMPTFSA. The reduction potentials were in the order of [AgCl3]2- > [AgBr3]2- > [AgI3]2-. The morphology of Ag deposits depended on the reduction potential. The diffusion coefficients of [AgCl3]2-, [AgBr3]2-, and [AgI3]2- were 2.5, 2.0, and 1.6 × 10-7 cm2 s-1, respectively. Formation of Ag nanoparticles dispersed in the ionic liquids was confirmed after potentiostatic cathodic reduction at -2.5 V using transmission electron microscopy.

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イオン液体中での金属析出・溶解反応への水晶振動子マイクロバランス

芹澤　信幸，片山靖

溶融塩および高温化学 62 ( 3 ) 162 - 169 2019.09

Research paper (conference, symposium, etc.), Joint Work

溶融塩系での常圧アンモニア電解合成技術の開発

錦織　徳二郎，芹澤　信幸，竹井　勝仁，伊藤　靖彦

溶融塩および高温化学 62 ( 2 ) 81 - 90 2019.04

Research paper (conference, symposium, etc.), Joint Work

Densities, Viscosities, and Refractive Indices of Binary Room-Temperature Ionic Liquids with Common Cations/Anions

Seki S., Serizawa N., Ono S., Takei K., Hayamizu K., Tsuzuki S., Umebayashi Y.

Journal of Chemical and Engineering Data (Journal of Chemical and Engineering Data) 64 ( 2 ) 433 - 441 2019.02

ISSN 00219568

Copyright © 2019 American Chemical Society. To elucidate the properties of binary system of room temperature ionic liquids (RTILs), we measured and compared the temperature dependence of densities, viscosities, and refractive indices of seven binary RTILs as well as neat RTILs. The observed densities, viscosities, and refractive indices of the binary systems showed intermediate properties between those of two starting RTILs. The values observed for the binary RTILs were only deviated from the values estimated based on the data of neat RTILs (±0.5%), and this deviation depended on both the combination of RTILs and the structures of the cation/anion. These results indicate that the properties of RTILs can be easily tuned by mixing RTILs depending on their applications.

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Electrochemical behavior of samarium species in an amide-type ionic liquid at different temperatures

Manjum M., Tachikawa N., Serizawa N., Katayama Y.

Journal of the Electrochemical Society (Journal of the Electrochemical Society) 166 ( 12 ) D483 - D486 2019

ISSN 00134651

© The Author(s) 2019. Electrochemical reaction of samarium (Sm) species was explored in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA), at 25 and 100°C. The cathodic and anodic current peaks corresponding to the reduction of Sm(III) and the oxidation of Sm(II), respectively, were observed in BMPTFSA containing Sm(TFSA)3 by cyclic voltammetry at 25°C. However, the anodic current peak corresponding to the oxidation of Sm(II) diminished significantly at lower scan rates when the temperature was elevated to 100°C, suggesting the disproportionation of Sm(II) at higher temperatures. Deposits were obtained on a glassy carbon electrode by potentiostatic cathodic reduction at -1.6 and -2.5 V in BMPTFSA containing Sm(TFSA)3 at 100°C. The deposits were found to contain Sm by energy dispersive X-ray spectroscopy (EDX), although no diffraction peak was observed by X-ray diffraction. The formation and dispersion of nanoparticles in the ionic liquid were also confirmed by transmission electron microscopy with and without exposure of the samples to air. The nanoparticles were considered to be metallic Sm, which was identified by electron diffraction and EDX. Sm nanoparticles were anticipated to be formed by the disproportionation reaction of Sm(II) to Sm(III) and Sm in the ionic liquid.

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Electrodeposition of Tin in an Amide Type Ionic Liquid Containing Chloride Ion

Maoko Sano, Naoki Tachikawa, Kazuki Yoshii, Nobuyuki Serizawa, Yasushi Katayama

Electrochemistry (Electrochemistry) 86 ( 5 ) 260 - 264 2018.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 13443542

© 2018 The Electrochemical Society of Japan, All rights reserved. Electrochemical behavior of Sn was investigated on a GC electrode in an aprotic ionic liquid, 1-butyl-1- methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing BMPCl and SnCl2 at 298K. SnCl2 was found to dissolve as [SnCl4]2- by potentiometry. The formal potential of [SnCl4]2-/Sn was -1.67V vs. Ag|Ag(I) (-1.24V vs. ferrocene|ferrocenium), which was more negative than that in BMPTFSA without chloride ions. Electrodeposition of Sn was possible by reduction of [SnCl4]2- in the ionic liquid. The dissociation of [SnCl4]2- was suggested from the diffusion coefficient of [SnCl4]2-. Tubular deposits with an inner diameter of 1-1.5μm were obtained in addition to granular deposits by potentiostatic cathodic reduction at -2.0V.

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Electrodeposition of Cadmium from Lewis Basic Hydrophobic Room-temperature Ionic Liquid

Shimul Saha, Naoki Tachikawa, Kazuki Yoshii, Nobuyuki Serizawa, Yasushi Katayama

Electrochemistry (Electrochemistry) 86 ( 5 ) 229 - 234 2018.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 13443542

© 2018 The Electrochemical Society of Japan, All rights reserved. Electrodeposition of cadmium (Cd) was investigated in a hydrophobic room-temperature ionic liquid, 1-butyl-1- methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) using CdCl2 as the source of Cd species in the presence of excess chloride ion. Raman spectroscopy and potentiometric measurement suggested formation of a cadmium tetrachlocomplex, [CdCl4]2-, in BMPCl/BMPTFSA. Cyclic voltammetry showed the possibility of electrochemical reduction from [CdCl4]2- to Cd(0) with interesting unusual electrochemical behavior, probably derived from the potential-dependent electric double layer structure typical to the ionic liquid. Electrodeposition of Cd was performed by potentiostatic electrolysis and the deposits were characterized by X-ray diffraction, energy dispersive X-ray analysis and scanning electron microscopy.

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Deposition and Dissolution of Copper on a Quartz Crystal Resonator in Contact with a Separator

Nobuyuki Serizawa, Yo Kobayashi, Hajime Miyashiro, Yasushi Katayama

Electrochemistry (Electrochemistry) 86 ( 5 ) 250 - 253 2018.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 13443542

© 2018 The Electrochemical Society of Japan, All rights reserved. Deposition and dissolution of copper were investigated by electrochemical quartz crystal microbalance (EQCM) technique using a Pt-coated quartz crystal resonator in contact with a separator in order to simulate the configuration of practical batteries. The admittance analysis indicated the quartz crystal resonated even in contact with a glass separator impregnated with the electrolyte under pressure. The mass change estimated from the change in the resonance frequency during deposition and dissolution of Cu on a Pt-coated resonator in contact with the separator was linearly related to the passed electric charge and closed to that without the separator, suggesting the mass monitoring according to Saurbrey equation is possible in the presence of the separator on the electrode. The highly sensitive mass monitoring with an overtone resonance was also found to be possible in the presence of the separator using the third harmonic vibration mode.

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Redox reaction of Tris(acetylacetonato)iron(III) complex in an amide-type ionic liquid

Tachikawa Naoki, Haruyama Ryo, Yoshii Kazuki, Serizawa Nobuyuki, Katayama Yasushi

Electrochemistry (Electrochemistry) 86 ( 2 ) 32 - 34 2018.01

ISSN 1344-3542

The redox reaction of tris(acetylacetonato)iron(III) (Fe(acac)3) on a glassy carbon electrode was investigated in 1- butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA). A one-electron transfer redox reaction of [Fe(acac)₃]^0/- showed the relatively negative potential of -1.4V vs. Ag|Ag(I). The diffusion coefficient of Fe(acac)₃ estimated by chronoamperometry was (1.4 + 0.1) × 10^-7cm² s^-1. The redox properties examined in this study suggested that the redox reaction of [Fe(acac)₃]^0/- can be utilized in the negative half-cell reaction of redox flow batteries.

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Determination of nitride ion electrochemically produced in a molten chloride system by ion chromatography

Takei Katsuhito, Serizawa Nobuyuki, Nishikiori Tokujiro, Ito Yasuhiko

Electrochemistry (Electrochemistry) 86 ( 2 ) 35 - 37 2018.01

ISSN 1344-3542

The cathodic reduction of nitrogen (N₂) gas in molten chloride was investigated using a porous nickel (Ni) electrode. A LiCl-KCl-CsCl melt containing cathodically formed nitride ion (N^3-) was sampled from an electrolytic bath and analyzed quantitatively by ion chromatography. The current efficiency of the cathodic reaction calculated from the ratio of quantity of the produced N^3- was approximately 78% on average. The main reason why the measured efficiency did not reach 100% is considered as the amount of N^3- increased more in the pores of the gas electrode than in the bulk of the electrolytic bath.

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Electrochemical formation of selenium nanoparticle in an amide-type ionic liquid

Sato Hiroki, Saha Shimul, Tachikawa Naoki, Yoshii Kazuki, Serizawa Nobuyuki, Katayama Yasushi

Electrochemistry (Electrochemistry) 86 ( 2 ) 57 - 60 2018.01

ISSN 1344-3542

Electrochemical formation of selenium (Se) nanoparticles in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing selenium tetrachloride (SeCl₄) was investigated in the presence of excess chloride anion on a glassy carbon electrode. Electrochemical reduction of [SeCl₆]^2- resulted in deposition of Se on the electrode surface. The deposited Se was further reduced electrochemically at the more negative potential region to form [Se₂]^2-, which was suggested to exist by ultraviolet-visible spectroscopy. Se nanoparticles dispersed in the ionic liquid were formed by the proportionation reaction between [SeCl₆]^2- and [Se₂]^2- in the ionic liquid. The Se nanoparticles were characterized by energy dispersive X-ray spectroscopy and transmission electron microscopy.

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Electrochemical study on aluminum speciation in Lewis acidic chloroaluminate-bis(trifluoromethylsulfonyl)amide mixed ionic liquids

Katayama Yasushi, Wakayama Takumi, Tachikawa Naoki, Yoshii Kazuki, Serizawa Nobuyuki

Electrochemistry (Electrochemistry) 86 ( 2 ) 42 - 45 2018.01

ISSN 1344-3542

Aluminum species forming in Lewis acidic chloroaluminate and bis(trifluoromethylsulfonyl)amide (TFSA^-) mixed ionic liquids having 1-butyl-3-methylimidazolium (BMI⁺) was investigated by potentiometry and Raman spectroscopy. A decrease in the concentration of [Al₂Cl₇]^- and an increase in that of [AlCl₄]^- with addition of BMITFSA into acidic BMICl-AlCl₃ were observed by Raman spectroscopy. The redox potential of Al(III)/Al in BMICl-AlCl₃ (1:2 in molar ratio) was found to be -0.68V vs. an Ag|Ag(I) reference electrode, which was corresponding to -0.25V vs. the ferrocene/ferrocenium couple at 25°C. The potentiometry of an Al electrode in the mixed ionic liquids with different compositions using the Ag|Ag(I) reference electrode suggested formation of a mixed ligand aluminum complex, Al(TFSA)Cl₂, indicating the instability of [Al₂Cl₇]^- against TFSA^-.

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Infrared spectra of N-H compounds in LiCl-KCl-CsCl molten salts using the diffuse reflectance optical system

Serizawa Nobuyuki, Takei Katsuhito, Nishikiori Tokujiro, Katayama Yasushi, Ito Yasuhiko

Electrochemistry (Electrochemistry) 86 ( 2 ) 88 - 91 2018.01

ISSN 1344-3542

The in-situ Fourier transform infrared spectroscopy of molten eutectic LiCl-KCl-CsCl was conducted in order to identify the dissolved ions in the molten salt electrolytes. The transflectance spectrum of the melts could be easily obtained at temperatures higher than 350°C using the commercially available diffuse reflectance optical system and an air-tight chamber with a built-in heater. The sharp absorption peak attributable to the stretching vibration of OH^- was observed in the melt containing LiOH, indicating the availability of identification of dissolved species in the melts. The intensities of transflection possibly assignable to N-H bonds in imide (NH^2-) and amide (NH₂ ^-) anions in the melt containing Li₃N changed during supplying H₂ gas because of the progress of the protonation reactions of these anions to form NH₃. The in-situ analysis of the dissolved ions in the melts under the reaction conditions by infrared spectroscopy with the diffuse reflectance optical system can be a simple and powerful tool for understanding the reaction mechanism.

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Redox reaction of 2, 2, 6, 6-tetramethylpiperidine-l-oxyI (TEMPO) in lithium bis(trifluoromethylsulfonyl)amide-tetraglyme solvate ionic liquid

Katayama Y., Wada K., Tachikawa N., Serizawa N.

ECS Transactions (ECS Transactions) 86 ( 14 ) 113 - 116 2018

© 2018 Electrochemical Society Inc.All rights reserved. The redox reaction of 2, 2, 6, 6-tetramethylpiperidine-l-oxyl (TEMPO) has been investigated in a solvate ionic liquid composed of lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) and tetraglyme (G4). The one-electron transfer and quasi-reversible redox reaction of TEMPO+/TEMPO was observed in the stable electrochemical potential window of the solvate ionic liquid. The formal potential of TEMPO'S/TEMPO was 0.19 V vs. Ferrocene/ferrocenium. The diffusion coefficients of TEMPO and TEMPO + at 298 K were 1.8 × 10 -7 and 7.6 × 10 -8 cm 2 s -1 , respectively, reflecting the coulombic interaction between the charged species with the anion of the solvate ionic liquid. The standard rate constant for the redox reaction of TEMPO + /TEMPO at 298 K was 1.9 × 10 -4 cm s -1 . Charge-discharge of a lithium secondary cell using a lithium-ion conductive glass-ceramics (LICGC) as a diaphragm and [Li(G4)]TFSA containing TEMPO as a catholyte was found to be possible with the average discharge voltage of 3.4 V.

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Design and New Energy Application of Ionic Liquids

Seki S., Ono S., Serizawa N., Umebayashi Y., Tsuzuki S., Ueno K., Watanabe M.

RSC Smart Materials (RSC Smart Materials) 2018-January ( 28 ) 365 - 389 2018

ISSN 20460066

© The Royal Society of Chemistry 2018. New electrochemical application using room-temperature ionic liquids (ILs) are introduced, such as lithium secondary batteries, electrochemical double layer capacitors, and novel types of electrical devices for sustainable and renewal energy society. ILs have so many combinations, owing to many cation/anion species. In this chapter, we introduce properties from fundamental (general and special physicochemical properties) to electrochemical applications of ILs. We also discuss importance of molecular design and application target of ILs.

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Long-cycle-life lithium-sulfur batteries with lithium solvate ionic liquids

Seki Shiro, Serizawa Nobuyuki, Takei Katsuhito, Umebayashi Yasuhiro, Tsuzuki Seiji, Watanabe Masayoshi

Electrochemistry 85 ( 10 ) 680 - 682 2017

ISSN 1344-3542

The electrochemical properties of a sulfur positive electrode in equimolar glyme-Li salt mixtures were investigated. Cyclic voltammograms indicated that the insertion of Li into the sulfur/carbon composite electrode took place over at least three steps during the reduction process. In contrast, the broad anodic current suggested that the electrode kinetics for the extraction of Li were relatively slow. Stable charge-discharge operation of the Li-S cell consisting of a Li negative electrode with [Li(triglyme)][bis(trifluoromethanesulfonyl)amide] as the electrolyte was achieved at 800 cycles. This indicates that dissolution of Li₂S_x into the electrolyte was effectively suppressed in this system.

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Effects of non-equimolar lithium salt glyme solvate ionic liquid on the control of interfacial degradation in lithium secondary batteries

Seki Shiro, Serizawa Nobuyuki, Takei Katsuhito, Tsuzuki Seiji, Umebayashi Yasuhiro, Katayama Yasushi, Miura Takashi, Dokko Kaoru, Watanabe Masayoshi

RSC Advances 6 ( 39 ) 33043 - 33047 2016

Control of interfacial properties between the electrode and electrolyte is important for obtaining long life-cycle lithium-ion secondary batteries. To control interfacial degradation, we investigated the effect of changing the composition ratio of lithium salt (LiN(SO₂CF₃)₂) and low-molecular-weight ether (CH₃-O-(C₂H₄O)₃-CH₃) in the system. A highly electrochemically stable lithium salt glyme solvated ionic liquid electrolyte was realized, with long-lived, robust lithium solvation complexes by increasing the lithium salt composition ratio. Lithium secondary batteries using the electrolyte show notable suppression of the degradation of interfacial resistance at the interface of the electrolyte and the positive electrode (high oxidation state), which leads to a longer life-cycle of the batteries.

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Electrochemical quartz crystal microbalance measurement of a Li4Ti5O12 composite electrode in a carbonate electrolyte

Serizawa Nobuyuki, Shono Kumi, Kobayashi Yo, Miyashiro Hajime, Katayama Yasushi, Miura Takashi

Journal of Power Sources 295 162 - 166 2015.07

Research paper (scientific journal), Joint Work, ISSN 0378-7753

Abstract Electrochemical quartz crystal microbalance (EQCM) measurement is conducted with a Li4Ti5O12 (lithium titanium oxide, LTO)-coated quartz crystal electrode in a carbonate electrolyte (ethylene carbonate + dimethyl carbonate; 50: 50 vol%) containing 1 M LiPF6. In-situ monitoring of the mass change during the charge and discharge of the LTO electrode can be achieved quantitatively because of the "zero-strain" property of LTO with Li+ insertion and the probably low reactivity between LTO and the electrolyte. The local changes of viscosity and density of the electrolyte contacting the LTO electrode are detected via the resonance resistance of the quartz crystal electrode, suggesting the local concentrations of Li+ and counter anion changed significantly during insertion and extraction of Li+ in the organic electrolyte.

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Static and transport properties of alkyltrimethylammonium cation-based room-temperature ionic liquids

Seki Shiro, Tsuzuki Seiji, Hayamizu Kikuko, Serizawa Nobuyuki, Ono Shimpei, Takei Katsuhito, Doi Hiroyuki, Umebayashi Yasuhiro

Journal of Physical Chemistry B 118 ( 17 ) 4590 - 4599 2014.05

ISSN 1520-6106

We have measured physicochemical properties of five alkyltrimethylammonium cation-based room-temperature ionic liquids and compared them with those obtained from computational methods. We have found that static properties (density and refractive index) and transport properties (ionic conductivity, self-diffusion coefficient, and viscosity) of these ionic liquids show close relations with the length of the alkyl chain. In particular, static properties obtained by experimental methods exhibit a trend complementary to that by computational methods (refractive index ∞ [polarizability/molar volume]). Moreover, the self-diffusion coefficient obtained by molecular dynamics (MD) simulation was consistent with the data obtained by the pulsed-gradient spin-echo nuclear magnetic resonance technique, which suggests that computational methods can be supplemental tools to predict physicochemical properties of room-temperature ionic liquids.

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常圧アンモニア電解合成法の高収率化に向けた要素技術開発－H–共存下でのNH3溶解機構－

芹澤信幸，竹井勝仁，錦織徳二郎，伊藤靖彦

電力中央研究所報告書 Q13004 2014.05

Research paper (other academic)

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