Electrochemical Behaviour of Sn on Cu Substrates in Acid Solutions at Different Temperatures

A. E. BOLZÁN; L. A. AZPETIA; C. A. GERVASI

Bolonia

Congreso; 69th Annual Meeting of the International Society of Electrochemistry; 2018

International Society of Electrochemistry

The electrochemical behavior of Sn on copper electrodes was studied at different temperatures ranging from 283 to 338 K in 1 M sulfuric acid solutions. Copper substrates appear as good candidates to produce Sn deposits that could serve, for instance, to develop new materials for anodes in lithium-ion batteries.Therefore, to advance in the knowledge of the electrochemical behavior of Sn(II) ions on copper electrodes, cyclic voltammetry and ring-disc electrode experiments along with potential steps and electrochemical impedance spectroscopy measurements were performed. These experiments were coupled with SEM analysis of the Sn deposits to characterize the resulting surface morphology. The voltammetric runs showed that the electrodeposition of Sn on Cu occurs at both, underpotential (upd) and overpotential (opd) conditions. The first situation was observed in the 0.0 to ca. -0.3 V (SHE) range and the second one from ca. -0.3 V downwards, depending on the scan rate and the solution temperature. The anodic/cathodic charge imbalance observed in the upd potential region suggests that part of the electrodeposited Sn diffuses into the Cu lattice and remains absorbed in the substrate. The appearance of a current loop due to the reactivation of the cathodic deposition during the anodic bias after reversing the potential scan in the initial descending part of the voltammetric current peak Ic indicates the presence of a nucleation and growth process. The corresponding chronoamperograms exhibited the corresponding net cathodic current peak within a very narrow potential window. Non-dimensional analysis of the current peaks showed a good agreement with a model of a progressive nucleation process under diffusion control. On the other hand, current transients obtained in the upd potential region exhibited no current peak suggesting that the electrodeposition of Sn is not related to the formation of nuclei on the Cu surface. SEM images showed that the Sn deposit formed under opd conditions involves particles with sizes in the 100-500 nm range for an electrodeposition time below 10s. Finally, Nyquist plots recorded between 60kHz and 10 mHz at the open circuit potential showed the presence of two capacitive time constants. Moreover, plots obtained under opd conditions showed, along with the two capacitive time constants, a Warburg contribution related to the diffusion of the Sn(II) ions to the reaction interface.