超声耦合隔膜电积锡电化学机理

Electrochemical mechanism of tin membrane electrodeposition in ultrasonic field

采用超声耦合隔膜电积技术从氯盐体系(Sn(Ⅱ)-Cl^--H_2O)中电积锡,通过循环伏安法、线性扫描伏安法、计时电流法及计时电位法,对比研究有无超声耦合条件下锡隔膜电积的电化学机理。循环伏安曲线及线性扫描曲线分析表明,超声耦合可使锡隔膜电沉积的控制步骤由无超声耦合时的扩散控制转变为有超声耦合时的电化学控制;超声耦合条件下提高温度、酸度及超声功率有利于锡的电积;计时电流测试表明,超声耦合锡隔膜电积初始过程遵循扩散控制的三维成核和晶粒长大机制,超声波在此过程起到细化晶粒及加快反应进程的作用。超声耦合后,锡的沉积由高择优取向(易产生锡"晶须")逐渐趋于无择优取向,阴极锡倾向于生成规则的网状结构,锡"晶须"得到遏制。同等条件下超声耦合更有利于获得结构更致密、形貌更平整的阴极锡。

Tin was electrodeposited from chloride solutions by using a membrane cell in ultrasonic field. Cyclic voltammetry（CV）, linear sweep voltammetry（LSV）, chronoamperometry （CHR） and chronopotentiometry were applied to investigate the electrochemical mechanism of tin electrodeposition under ultrasonic field. Cyclic voltammetry and linear sweep voltammetry diagrams analysis shows that the application of ultrasound can change the tin membrane electro-deposition reaction from diffusion control to electrochemical control, and the increasing of temperature, acidity and ultrasonic power is beneficial to tin electrodeposition. Chronoamperometry curves show that the initial process of tin electrodeposition follows the diffusion controlled three-dimensional nucleation and grain growth mechanism. The coupling ultrasonic field plays a role in refining the grain and accelerating the electro-deposition reaction in this process, and the high preferential orientation of tin （tin whisker） tends to be no preferred orientation. The tin deposition tends to form regular network structure, and the tin whisker can be restrained. The ultrasonic coupling is more favorable to obtain the more compact and more smooth cathode tin under the same condition.