Electrochemical migration of tin in thin electrolyte layer containing chloride ions

• Novel approach to the study of electrochemical migration in thin electrolyte layers.
• Tin dendrites tend to grow in electrolytes of low and high Cl− concentration.
• Tin dendrites do not grow in electrolytes of medium Cl− concentration.
• Real time observation of pH distribution on the electrodes.
• Precipitates consist of stannic and stannous hydroxides or oxides.

The electrochemical migration of tin in thin electrolyte layers (TELs) containing chloride ions was investigated using in situ electrochemical and optical techniques, as well as ex situ characterization. The results show that tin dendrites co-exist with precipitates in both low and high chloride concentrations, however, in intermediate chloride concentration, no tin dendrites but only precipitates mainly consisting of stannic compounds were observed. The higher bias voltage is applied, the faster rate of ions migration is. Mechanisms have also been proposed to explain the electrochemical migration behaviors.