Rao Jun, Vijayaraghavan R, Zhou Yundong, Howlett Patrick C, MacFarlane Douglas R, Forsyth Maria, Zhu Haijin
ARC Centre of Excellence for Electromaterials Science (ACES), Institute for Frontier Materials (IFM), Deakin University, Melbourne Campus at Burwood, Burwood VIC 3125, Australia.
Phys Chem Chem Phys. 2018 Feb 7;20(6):4579-4586. doi: 10.1039/c7cp07330e.
Proton conductors are widely used in different electrochemical devices including fuel cells and redox flow batteries. Compared to conventional proton conducting polymer membranes, protic organic ionic plastic crystal (POIPC) is a novel solid-state proton conductor with high proton conductivity even under anhydrous conditions. In this work, different organic protic salts based on the same parent di-functional cation with different anions were synthesized and characterized. It is found that the di-protonated cation plays an important role in defining the thermal properties, leading to stronger plastic crystal behavior and a higher melting point. Static solid-state NMR and the synchrotron XRD results show that the di-protonated cation allows greater dynamics in the crystal in contrast to the mono-protonated counterparts. The 1-(N,N-dimethylammonium)-2-(ammonium)ethane triflate ([DMEDAH][Tf]) has the highest ionic conductivity of 1.1 × 10 S cm at 50 °C, whereas the bis(trifluoromethanesulfonyl)amide counterpart [DMEDAH][TFSA] has the lowest ionic conductivity (2.8 × 10 S cm at 50 °C) with no measureable mobile ion component at this temperature. The fraction of mobile species is significantly suppressed in the TFSA containing salts as against the Tf systems.
质子导体广泛应用于包括燃料电池和氧化还原液流电池在内的不同电化学装置中。与传统的质子传导聚合物膜相比，质子有机离子塑性晶体（POIPC）是一种新型的固态质子导体，即使在无水条件下也具有高质子传导率。在这项工作中，合成并表征了基于相同母体双功能阳离子和不同阴离子的不同有机质子盐。研究发现，双质子化阳离子在定义热性质方面起着重要作用，导致更强的塑性晶体行为和更高的熔点。静态固态核磁共振和同步加速器X射线衍射结果表明，与单质子化对应物相比，双质子化阳离子使晶体具有更大的动力学。1-(N,N-二甲基铵)-2-(铵)乙烷三氟甲磺酸盐([DMEDAH][Tf])在50℃时具有最高的离子电导率，为1.1×10 S cm，而双(三氟甲磺酰基)酰胺对应物[DMEDAH][TFSA]在50℃时具有最低的离子电导率(2.8×10 S cm)，在此温度下没有可测量的移动离子成分。与Tf体系相比，含TFSA盐中移动物种的比例受到显著抑制。
