Effect of Anodic Passivation at High Applied Potential Difference on the Crystal Shape and Morphology of Copper Electrodeposits: Thermodynamics and Kinetics of Electrocrystallization

Abstract

In this paper, we discuss the effect of potential difference and current density on the crystal morphologies of copper electrodeposits. Their individual roles have been identified by creating a passivation layer in situ at the anode during deposition, which instantaneously reduces the current density in the system while maintaining a high potential difference. It is observed that the crystal shape is decided by the potential difference and current density determines the rate at which that shape is achieved. In a copper system, at high overpotentials, coherent twin boundaries are formed due to their low formation energy as compared to high angle grain boundaries, high index surface planes, etc. Without the presence of any foreign species like H 2 bubbles during the crystallization process, the slowest growth direction is identified to be <1 1 1>. The passivation layer is formed due to a pH distribution in the electrolyte caused by the high electric field. A new methodology to explain the formation of the passivation layer is proposed, which is performed by analyzing the current transients generated using Kirchhoff's Laws.

The generalized solubility limit approach for vanadium based cathode materials for lithium-ion batteries

“…In some cases, it still allows an electrode to operate as a quasi-reference electrode, which is very much needed for two-electrode based systems such as coin-cell electrochemical testing. 45 On the other hand, it is observed that this passivation layer is thicker when relatively dilute electrolytes are used. Furthermore, a thick passivation layer can lead to a drastic voltage drop at the lithium foil surface, which is the reference electrode in a half-cell configuration.…”

Substrate effect on electrodeposited copper morphology and crystal shapes

“…Out of all, cetyl trimethyl ammonium bromide (CTAB) is of keen interest because it is known to inhibit the growth of (111) planes [21-23]. It has been extensively reported that the morphology and grain size of a deposit depend on current density and bath chemistry [24-35]. But the effect of the substrates in determining the crystal shapes is not much explored.…”