Cooperative Proton and Li‐ion Conduction in a 2D‐Layered MOF via Mechanical Insertion of Lithium Halides
Marvin K. Sarango‐Ramírez, Masaki Donoshita, Yukihiro Yoshida, Dae‐Woon Lim, Hiroshi Kitagawa
Abstract
Abstract Ionic conduction in highly designable and porous metal–organic frameworks has been explored through the introduction of various ionic species (H + , OH − , Li + , etc.) using post‐synthetic modification such as acid, salt, or ionic liquid incorporation. Here, we report on high ionic conductivity ( σ >10 −2 S cm −1 ) in a two‐dimensionally (2D)‐layered Ti‐dobdc (Ti 2 (Hdobdc) 2 (H 2 dobdc), H 4 dobdc: 2,5‐dihydroxyterephthalic acid) via LiX (X=Cl, Br, I) intercalation using mechanical mixing. The anionic species in lithium halide strongly affect the ionic conductivity and durability of conductivity. Solid‐state pulsed‐field gradient nuclear magnetic resonance (PFG NMR ) verified the high mobility of H + and Li + ions in the temperature range of 300–400 K. In particular, the insertion of Li salts improved the H + mobility above 373 K owing to strong binding with H 2 O. Furthermore, the continuous increase in Li + mobility with temperature contributed to the retention of the overall high ionic conductivity at high temperatures.