Ionic Liquid-Based Electrolytes Containing Surface-Functionalized Inorganic Nanofibers for Quasisolid Lithium Batteries

Takahiro Yuuki; Yuichi Konosu; Minoru Ashizawa; Takashi Iwahashi; Yukio Ouchi; Yoichi Tominaga; Rie Ooyabu; Hajime Matsumoto; Hidetoshi Matsumoto

doi:10.1021/acsomega.6b00480

Ionic Liquid-Based Electrolytes Containing Surface-Functionalized Inorganic Nanofibers for Quasisolid Lithium Batteries

ACS Omega. 2017 Mar 7;2(3):835-841. doi: 10.1021/acsomega.6b00480. eCollection 2017 Mar 31.

Authors

Takahiro Yuuki¹, Yuichi Konosu¹, Minoru Ashizawa¹, Takashi Iwahashi¹, Yukio Ouchi¹, Yoichi Tominaga², Rie Ooyabu³, Hajime Matsumoto³, Hidetoshi Matsumoto¹

Affiliations

¹ Department of Materials Science and Engineering, Tokyo Institute of Technology, Mail Box S8-27, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
² Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
³ Department of Energy and Environment, Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.

Abstract

In the present study, surface amino-functionalized silica nanofibers (f-SiO₂NFs, average diameter = 400 and 1000 nm) are used as one-dimensional (1-D) fillers of ionic liquid (IL)-based quasisolid electrolytes. On adding f-SiO₂NFs to an IL (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, EMITFSA) containing lithium bis(trifluoromethanesulfonyl)-amide (LiTFSA), the well-dispersed 1-D nanofillers easily form a three-dimensional network structure in the IL, function as physical cross-linkers, and increase the viscosity of the composites, consequently providing a quasisolid state at a 3.5 wt % fraction of the NFs. Rheological measurements demonstrate that the prepared composites exhibit "gel-like" characteristics at 40-150 °C. All prepared composites show high ionic conductivities, on the order of 10^-3 S cm^-1, around room temperature. To investigate the additive effect of f-SiO₂NFs in the composites, the lithium transference numbers are also evaluated. It is found that thinner NFs enhance the transference numbers of the composites. In addition, quasisolid lithium-ion cells containing the prepared composites demonstrate relatively high rate characteristics and good cycling performance at high temperature (125 °C).