有机镁/THF电解液中镁电化学沉积的研究

Study of magnesium electrodeposition in THF solutions containing organic magnesium complexes

制备了3种有机镁Mg-Al-R-Cl(F)络合物THF电解质溶液,研究了电解液中镁在不同金属基质(银、铜、镍及不锈钢)上的沉积与溶出。利用循环伏安(CV)及扣式电池的充放电测试,比较了几种电解液中镁在不同金属基质上的电沉积性能。结合X-射线衍射(XRD)对金属基质上的沉积镁进行了相组成分析。结果表明,三种电解液中不同金属基质上都可以实现镁的电化学沉积与溶出,其中,MgBu2-AlF3/THF电解液中的沉积过电位为最小,Mg(AlCl2EtBu)2/THF电解液阳极分解电位最高;而3种电解液中均以基质银上镁沉积-溶出的效果最佳,过电位小,循环效率最高。银-镁合金(α'-Ag3Mg)的生成促进了镁在银基质上的沉积。在铜、镍及不锈钢基质上,没有相应合金相生成,因此导致不同的电化学行为。

Three kinds of THF solutions containing Mg-Al-R-Cl （F） complexes were prepared, and the magnesium electrochemical deposition -dissolution on different metal substrates（Ag, Cu, Ni, and steel） in the electrolytes was studied. Cyclic vohammetry （CV） and steady- state charge/discharge of coin type cells were used to study the effects of magnesium deposition and dissolution on different metal substrates in the electrolytes. X - ray diffraction （XRD） was used to observe the structure and morphology of the magnesium deposits. The lowest overpotential was obtained in the MgBu2- AlF3 /THF electrolyte, while the anodic stability of Mg（AlChBuEt）2 is superior to the others. And the best results were found on silver in all the three electrolytes, on which electrodeposited magnesium could alloy with the substrate to form α＇- Ag3Mg phase. The formation of silver- magnesium alloy decreased the overpotential for electrochemical magnesium deposition- dissolution and promotes the cycling efficiency. No similar alloying reaction was observed on copper, nickel, or steel, resulting in the different electrode performance.