In situ study of the electrochemical migration of tin in the presence of H2S

Abstract

The electrochemical migration of tin in the presence of H2S was in situ investigated using optical and electrochemical techniques. The results show that dendrites co-exist with precipitates at H2S concentration range from 0 to 1000 ppmv; furthermore, the time to short circuit decreases with increasing H2S concentration. The essential reason is that higher H2S concentration increases the conductivity of electrolyte, resulting in a higher growth rate of dendrite. As the H2S concentration further increases up to 10,000 ppmv or 100,000 ppmv, no dendrites but precipitates can be observed. This can be attributed to that large amount of tin hydroxides and tin sulfides are produced quickly at the beginning of electrochemical migration test, which act as a barrier to hinder the arrival of Sn2+/Sn4+ to the cathode. Thus, no dendrites but precipitates can be found. Under square wave electric field with a time period of 1 s, it is observed that there are no dendrites but some precipitates. This is because there is a circulation between metal tin deposition during the first 0.5 s and its dissolution in the next 0.5 s. Therefore, the occurrence of short circuit in the presence of H2S is semi-cycle dependent.