基体对流动锌酸钾碱液中锌电沉积的影响

Effects of Substrates on Deposition of Zinc from Flowing Alkaline Zincate Solutions

在流动的高浓度锌酸钾碱液中研究了镍箔和镀镍冲孔钢带基体电极对锌沉积/溶解电化学行为的影响.结果表明,在流动电解液中电极表面浓度梯度变化不大,不同基体上均未出现锌沉积的阴极峰;扫描速度超过10 mV/s,循环伏安曲线基本不随扫速变化,说明锌的沉积/溶解峰电流不仅与扫描速度有关,还取决于锌沉积的时间.采用镀镍冲孔钢带基体兼有析氢过电位大和稳定性好的特点,又由于其特殊的冲孔结构,改变了传质方式,锌沉积的极化降低,孔的周围形成紧密堆积的沉积锌,锌沉积的电流和电量大,沉积效率高,经4次充放电循环后,库仑效率即达95%以上,是性能较佳的基体电极.

The effects of substrates including nickel foil, nickel-plated perforated steel strip, on deposition/ dissolution behavior of zinc from flowing concentrated alkaline zincate solutions were investigated. The results show that almost no changes of concentration differences occur in flowing electrolytes, leading to no cathodic peaks appearing in cyclic voltammograms. At a scan rate above 10 mV/s, no variation of vohammograms for the zinc deposition/dissolution with scan rate is observed. This indicates that zinc deposition/dissolution peak currents are not only dependent on scan rate but also related to the time of zinc deposition. The substrate, nickel-plated perforated steel strip, is characterized by high-H2-overpotential to excellent chemical stability. The mode of mass transportation is changed due to its special perforated structure. As a result, the polarization of zinc deposition is effectively reduced. Piled tightly zinc deposition is formed around the pores of the sub- strate. High zinc deposition efficiency is obtained with large current and capacity of zinc deposition. After 4 charge-discharge cycles, the coulombic efficiency reaches over 95%. Therefore, the nickel-plated perforated steel strip is a favorable substrate electrode suited for zinc deposition from flowing alkaline zincate solutions.