磁场对离子液体中电沉积铝的作用

The electrolytic aluminum industry is the largest electrochemical industry. The electrodeposition of aluminum in the ionic liquid has more advantages than the traditional electrolytic aluminum technology. However, the technology of the electrodepostion of aluminum in the ionic liquid exist some problems, such as the loose and easily off of the aluminum layer and it is difficult to obtain the thickness and density electrodeposited aluminum layer in the ionic liquid. According to the magnetic effect on the electron transfer and the polarity electric particles transport and distribution, the magnetic field was introduced during the electrodeposition of aluminum in the 1-Ethyl-3-methylimidazolium chloride ionic liquid. In order to know the magnetic effect and its mechanism on the behavior of the interface during the electrodeposition of aluminum in the ionic liquid, the magnetic effect and its mechanism on the electric double layer , the process on the working electrode and the behavior of the electrodeposition of aluminum on the interface should been investigated. The investigation should provide the theory support to synthesis the thickness and density aluminum electrodeposited layer in the ionic liquid. In this way, to enrich the interface theories about molten salt electrochemistry, it should supply a basis and technological lead to the effective, economic energy and friendly to the environment of the aluminum metallurgy.

电解铝工业是最大的熔盐电化学工业。离子液体中电沉积铝较传统铝电解具有优势。针对离子液体中电沉积铝过程存在铝层松散，易脱落，不易厚积、不致密的问题。根据磁场对电子转移和极化带电粒子的作用，本项目提出在氯化1-乙基-3-甲基-咪唑离子液体中电沉积铝过程引入磁场作用，通过研究磁场对电极界面双电层行为、电极过程行为和铝电沉积界面行为的作用机制及调控机理，弄清磁场对离子液体中电沉积铝界面行为作用机制及调控，为实现离子液体中厚积、致密的铝沉积层的强化制备提供理论基础和技术借鉴，为高效、低能耗、低污染的铝冶金提供理论借鉴和技术支撑。丰富熔盐电化学法固相电沉积界面过程的理论。

离子液体中电沉积铝较传统铝电解不但使电解温度降至室温，还可减少设备腐蚀和环境污染。但离子液体中电沉积得到的铝层薄，易脱落，不易厚积，不致密。根据马库斯的“电子转移理论”，本项目提出在氯化1-乙基-3-甲基-咪唑离子液体中铝电沉积过程引入磁场进行研究。. 项目对[EMIM]Cl-AlCl3离子液体中电沉积铝进行了研究，通过改变电流密度，沉积时间和施加磁场等方法对铝沉积层的形貌进行调控，并采用循环伏安、计时电流、交流阻抗、微分电容和恒电流密度沉积等方法研究了磁场对铝电沉积电极过程、电极界面双电层行为和电沉积铝结晶成核的影响，考察了磁场强度、电流和沉积时间对铝沉积层的影响，通过正交实验找出了离子液体中电沉积铝的最佳工艺条件。. 研究发现：磁场增大了铝电沉积电极/离子液体中双电层电容，提高了电化学电子转移速率，双电层变薄，与马库斯提出的“电子转移理论”相符；铝在玻碳电极、铜电极上的沉积均符合电化学极化控制的三维瞬时成核机理，磁场作用使电沉积铝更易成核，而且晶核较小；电沉积铝的影响因素主次顺序为磁场强度、电流、沉积时间，合适的工艺条件：在[EMIM]Cl和AlCl3摩尔配比1:2离子液体中，磁场强度36.9mT，电流0.0035A，沉积时间3h，此条件下铝沉积层致密，厚度约为78.94μm。. 铝的形貌对其作为锂离子电池负极材料循环性能有较大影响。离子液体中电沉积铝具有电流效率高，易操作，可调控产物形貌等优点。在B=60 mT微磁场条件下，以6 mA•cm-2恒电流密度电沉积4 h得到的由多个半球形表面构成的铝材料电化学性能最佳，在100 mAh•g-1的能量密度，60%的放电深度进行充放电循环条件下，此材料的循环次数为140次。