I. Wen Sun

Improved Corrosion Resistance of Magnesium Alloy with a Surface Aluminum Coating Electrodeposited in Ionic Liquid

A metallic aluminum (Al) layer was successfully electrodeposited onto a magnesium (Mg) alloy in a Lewis acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl 3 -EMIC) ionic liquid under a galvanostatic condition at room temperature. Effects of deposition current density on material characteristics of the deposited layers were explored by means of a scanning electron microscope and an X-ray diffractometer. In addition, the improvement in corrosion resistance of the Mg alloy due to the Al coating was evaluated by electrochemical measurements and a salt spray test. The electrochemical impedance spectroscopic data indicated that a bare Mg alloy had a polarization resistance of only 470 Ω cm 2 in 3.5 wt % NaCl solution, whereas the Al-coated Mg sample showed its resistance as high as 8700 Ω cm 2 in the same environment. Moreover, it was also found that the Al layer deposited at a lower current density was more compact and uniform when compared to that deposited at a higher current density; consequently, this coating revealed a superior protection capability for the Mg substrate against corrosion.

Evaluation of Ionic Liquid Electrolytes for Use in Manganese Oxide Supercapacitors

Development of Mn oxide supercapacitors incorporating ionic liquid IL electrolytes was attempted. The experimental resultsindicate the possibility of achieving pseudocapacitive performance of Mn oxide in ILs without involving protons and alkalications, thus opening a route of developing electrolytes for oxide-based pseudocapacitors. In 1-ethyl-3-methylimidazolium-dicyanamide aprotic IL, Mn oxide can exhibit a specific capacitance of 72 F/g in a potential window of 2 V. Due to high ionicconductivity, large electrochemical windows, excellent thermal stability, and nonflammability of the IL, a high-voltage andlong-life energy storage system is successfully proposed.© 2008 The Electrochemical Society. DOI: 10.1149/1.3013028 All rights reserved.Manuscript submitted August 18, 2008; revised manuscript received October 3, 2008. Published November 6, 2008.