Prediction of Morphological Properties of Smart-Coatings for Cr Replacement, Based on Mathematical Modelling

Abstract

In this paper we present an extension of a mathematical model for the morphological evolution of metal electrodeposits – recently developed by some of the authors – accounting for mass-transport of electroactive species from the bulk of the bath to the cathode surface. The implementation of mass-transport effects is specially necessary for the quantitative rationalisation of electrodeposition processes from ionic liquids, since these electrolytes exhibit a viscosity that is notably higher than that of cognate aqueous solutions and consequently mass-transport control is active at all practically relevant plating rates. In this work we show that, if mass-transport is coupled to cathodic adsorption of ionic liquid species and surface diffusion of adatoms, it can lead to electrodeposit smoothing. This seemingly paradoxical theoretical result has been validated by a series of Mn electrodeposition experiments from aqueous baths and eutectic ionic liquids. The latter solutions have been shown to be able to form remarkably smoother coatings than the former ones. Mn electroplates have been proposed for Cd replacement and their corrosion protection performance seems comparable, but so far the required surface finish quality has not been achieved with aqueous electrolytes. Ionic liquids thus seem to provide a viable approach to aeronautic-grade Mn electroplating.

Spatio-temporal organization in a morphochemical electrodeposition model: Hopf and Turing instabilities and their interplay

“…In a series of recent papers [7][8][9][10][11][12][13][14][15] and [63] we used the reaction-diffusion modelling approach to rationalize the formation of morphological patterns in electrodeposition. The novelty of our approach was to consider more natural state variables: the morphology (surface profile) -that is the crucial observable -and the surface chemistry (composition) -that in fact controls the growth process -coupled through non-linear and physically straightforward electrochemical source terms.…”

Operando soft X‐ray microscope study of rechargeable Zn–air battery anodes in deep eutectic solvent electrolyte

“…In both figures, the formation, development, and branching of dendritic unstable outgrowth features can be clearly seen. Within the population of dendrites, a subpopulation is progressively selected, coherently with the mass‐transport–controlled mechanism . Cognate work on in situ dynamic imaging of Zn growth by hard X‐ray transmission microscopy is known in the literatures: The former reference investigated the structural and morphological impact of Bi additions in zincate electrolytes, with combined microdiffraction work, whereas the latter concentrated on additive effects in DES electrolytes.…”

Electrodeposition of a Mn–Cu–ZnO Hybrid Material for Supercapacitors: A Soft X‐ray Fluorescence and Absorption Microspectroscopy Study

“…Co-electrodeposition of elements with different electrochemical nobilities, such as Zn, Mn, and Cu, is a challenging issue, [23] further complicated in the present case by the precipitation of oxy-hy- Synchrotron-based soft-X-ray imaging and microspectroscopy with sub-micrometer spatial resolution are used to investigate the electrodeposition of Mn-Cu-ZnO, a prospective active material for supercapacitors. Co-electrodeposition of elements with different electrochemical nobilities, such as Zn, Mn, and Cu, is a challenging issue, [23] further complicated in the present case by the precipitation of oxy-hy- Synchrotron-based soft-X-ray imaging and microspectroscopy with sub-micrometer spatial resolution are used to investigate the electrodeposition of Mn-Cu-ZnO, a prospective active material for supercapacitors.…”

“…Despite the extensive studies to date, there are missing chains in the characterization of electrochemical material growth process, which leaves open questions about compositional and functional properties of the electrodeposits. Co-electrodeposition of elements with different electrochemical nobilities, such as Zn, Mn, and Cu, is a challenging issue, [23] further complicated in the present case by the precipitation of oxy-hy-Synchrotron-based soft-X-ray imaging and microspectroscopy with sub-micrometer spatial resolution are used to investigate the electrodeposition of Mn-Cu-ZnO, a prospective active material for supercapacitors. This study is focused on the correlation of the local current density and the spatial distribution of the composition and chemical-state in electrodeposits grown potentiostatically at À0.7 V (vs a saturated calomel electrode), as well as the optimal potential for the achievement of high specific capacitance and cycling stability.…”