碳酸乙烯酯添加剂对BMImBF4离子液体作为镁沉积—溶解电解液的改性研究

利用恒电流沉积-溶解、交流阻抗、XRD和SEM方法研究了在室温下EC(碳酸乙烯酯)添加剂对BMImBF₄离子液体作为镁沉积电解液的改善情况. 在Mg(CF₃SO₃)₂浓度为0.3 mol?L^－1的BMImBF₄电解液中加入w＝5%(质量分数)的EC后, 沉积—溶解循环过程更加稳定, 并且循环次数明显增加, 可以达到265次以上; 交流阻抗结果显示, 膜电阻和电荷转移电阻有所减少; 从SEM图可以观察到, 在沉积初期原本枝晶态的镁在加入EC后以颗粒状沉积. 可能是EC添加剂在反应中形成的低聚物覆盖在镁的表面, 抑制了枝晶的形成.

Study on Modification of BMImBF4 Ionic Liquid as the Electrolyte of Magnesium Deposition-Dissolution with Ethylene Carbonate Additive

The effect of ethylene carbonate (EC) additive to BMImBF₄ ionic liquid as the electrolyte of magnesium deposition-dissolution was studied by constant current deposition-dissolution, AC impedance, X-ray diffraction and scanning electron microscope (SEM) measurements. After adding w＝5% EC in the ionic liquid of BMImBF₄ with 0.3 mol?L^－1 Mg(CF₃SO₃)₂, deposition-dissolution results exhibited that the process became more stable and the cyclic number was effectively improved, and impedance measurements showed that the surface film resistance and charge-transfer resistance became lower, and SEM results presented that the dendritic deposits evolved to particulate morphology and a thinner surface film was formed. The EC derived surface film, which may consist of polymeric species, suppressed the formation of dendritic magnesium.