Fast fluoride ion conduction of NH4(Mg1-xLix)F3-x and (NH4)2(Mg1-xLix)F4-x assisted by molecular cations

Kota Motohashi; Yosuke Matsukawa; Takashi Nakamura; Yuta Kimura; Naoaki Kuwata; Yoshiharu Uchimoto; Koji Amezawa

doi:10.1038/s41598-022-09835-0

Fast fluoride ion conduction of NH₄(Mg_1-xLi_x)F_3-x and (NH₄)₂(Mg_1-xLi_x)F_4-x assisted by molecular cations

Sci Rep. 2022 Apr 8;12(1):5955. doi: 10.1038/s41598-022-09835-0.

Authors

Kota Motohashi^{1

2}, Yosuke Matsukawa³, Takashi Nakamura⁴, Yuta Kimura⁴, Naoaki Kuwata⁵, Yoshiharu Uchimoto⁶, Koji Amezawa⁷

Affiliations

¹ Graduate School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi, 980-8579, Japan. kota.motohashi@chem.osakafu-u.ac.jp.
² Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan. kota.motohashi@chem.osakafu-u.ac.jp.
³ Graduate School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi, 980-8579, Japan.
⁴ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi, 980-8577, Japan.
⁵ National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
⁶ Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
⁷ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi, 980-8577, Japan. koji.amezawa.b3@tohoku.ac.jp.

Abstract

Aiming development of the fast anion conductors, we proposed a new material design using flexible molecular cation as a host cation, and demonstrated it with fluoride ion conduction in NH₄MgF₃ and (NH₄)₂MgF₄ based materials. Dominant fluoride ion conduction with relatively high conductivities of 4.8 × 10^-5 S cm^-1 and 8.4 × 10^-6 S cm^-1 were achieved at 323 K in (NH₄)₂(Mg_0.85Li_0.15)F_3.85 and NH₄(Mg_0.9Li_0.1)F_2.9, respectively. It is implied that the molecular cation in the host lattice can assist the anion conduction. Our findings suggest molecular cation-containing compounds can be attractive material groups for fast anion conductors.

Abstract

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