咪唑类离子液体中镁的可逆沉积-溶出性能

Deposition-dissolution properties of magnesium in imidazolium-based ionic liquids

采用循环伏安、恒电流充放电、X射线衍射、扫描电镜技术研究含有三氟甲基磺酸镁的1-乙基-3-甲基咪唑四氟硼酸盐、1-丁基-3-甲基咪唑四氟硼酸盐、1-丁基-2,3-二甲基咪唑四氟硼酸盐、1-丁基-2,3-二甲基咪唑鎓双三氟甲基磺酰亚胺盐4种离子液体中镁的沉积与溶出行为以及沉积物的组成和形貌。结果表明:在咪唑阳离子基团中增加1-位碳上烷基链的长度和在2-位碳上引入甲基可以提高咪唑阳离子的还原稳定性,拓宽电解液还原电位窗口到-1 V(vs Mg RE);同时采用TFSI-阴离子可使电解液阳极氧化电位拓宽到3.1 V(vs Mg RE)以上;适量添加有机溶剂THF可增加Mg2+的还原-氧化峰电流,降低峰电位差,提高可逆性。

The deposition-dissolution performance of magnesium in four imidazolium-based ionic liquids, 1-ethyl-3- methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, 1-butyl-2,3-dimethylimidazolium bis（（trifluoromethyl）sulfonyl）imide containing Mg（CF3SO3）2 used as the electrolytes was studied by cyclic voltammogramms and constant current discharge-charge techniques. X-ray diffraction and scanning electron microscope measurements were conducted to characterize the components and morphologies of deposits. The results show that the cathodic satiability of imidazolium cations can be improved by increasing the length of alkyls at the first position and introducing methyl group at the second position of the imidazolium cations, and the cathodic limit of the electrolytes can be widen to -1 V （vs Mg RE）, The anodic limit of the electrolyte with TFSV anion can reach to 3.1 V （vs Mg RE）. After adding appreciate amount of THF organic solvent, the peak currents and reversibility of Mg^2＋ reduction-oxidation can be improved.