Effects of mechanical grinding on the phase behavior and anhydrous proton conductivity of imidazolium hydrogen succinate

Isotropic Anhydrous Superprotonic Conductivity Cooperated with Installed Imidazolium Molecular Motions in a 3D Hydrogen‐Bonded Phosphate Network

“…Moreover, the anhydrous proton conductivity reported herein is the highest among those previously reported for molecular phosphate crystals within the same temperature range (Figure 4). Notably, many previous studies that reported σ used a compressed powder sample; thus, extrinsic effects, such as those from defects or grain boundaries, could have been involved [31, 46] …”

“…In this context, anhydrous crystalline proton conductors, such as those based on metal–organic frameworks, covalent organic frameworks, hydrogen‐bonded organic frameworks, and polyoxometalates, have been rigorously studied [16–21] . Especially, the conductors based on molecular crystals can be considered the ideal platform [3, 22–31] . Their well‐defined molecular arrangements are advantageous for regularly imparting a host material with molecule‐specific properties (e.g., the number of hydrogen‐bond (H‐bond) sites, acidity, and dynamic properties) and for investigating the conduction mechanism to develop material design guidelines.…”

“…Herein, we demonstrate the installation of imidazolium ( ImH + ) into a three‐dimensionally extended H‐bonded phosphate network to accelerate proton conduction via the phosphate network through the molecular motions of ImH + . ImH + is one of the most employed constituents for anhydrous molecular proton conductors, which were recently shown to exhibit molecular motions that contribute to proton conduction in molecular crystals [28–31, 35–43] . In this study, we focused on the 1 : 2 salt of Im and phosphoric acid, i.e., phosphoric acid imidazolium dihydrogen phosphate (= 1 ; Figure 1).…”

“…[16][17][18][19][20][21] Especially, the conductors based on molecular crystals can be considered the ideal platform. [3,[22][23][24][25][26][27][28][29][30][31] Their well-defined molecular arrangements are advantageous for regularly imparting a host material with molecule-specific properties (e.g., the number of hydrogen-bond (H-bond) sites, acidity, and dynamic properties) and for investigating the conduction mechanism to develop material design guidelines. However, such anhydrous superproton-conductive molecular crystals are limited.…”

Anhydrous proton-conducting imidazole triflate-SiO2 composite

“…Formation of an acid-base composite material between ImiH and various organic acids is the most common route due to the large number of organic acids and the simple synthesis process. Methanesulfonic acid, dicarboxylic acids (succinic acid, glutaric acid), phthalic acid were used to form proton conduction salts with imidazole [ 8 , 9 , 10 , 11 , 12 , 13 ]. ImH in ImiH—Al(H 2 PO 4 ) 3 composite remained solid up to 130 °C without any sudden drop in conductivity in the region below 90 °C [ 14 ].…”