Hydrogen Bubbles and the Growth Morphology of Ramified Zinc by Electrodeposition

Abstract

Real-time X-ray microscopy was used to study the influence of hydrogen-bubble formation on the morphology of ramified zinc electrodeposit. The experimental results show that when intense hydrogen bubbling occurs at high potential, the morphology of the ramified zinc deposit changes from dense-branching to fern-shaped dendrite. The fern-shaped dendrite results in part from the constricted growth due to hydrogen bubbles but also from the highly concentrated electric field. The fern-shaped dendrite morphology was observed during the early stages of electroplating for both the potentiostatic and galvanostatic modes; however, the deposit plated in the galvanostatic mode densified via lateral growth during the later plating stages. This indicates that potentiostatic plating for which the hydrogen-bubble formation steadily occurs throughout the electrodeposition process is better than galvanostatic plating for fabricating fern-shaped deposits, which are ideal electrodes for Zn–air batteries due to the relatively large specific area.

Modelling the dynamic growth of copper and zinc dendritic deposits under the galvanostatic electrolysis conditions

“…This fact was noted earlier [19,20] but researchers began to put special focus on it in later works [4][5][6][7][8][9][10][11]21]. In most studies [4][5][6][7][8][9][10] the current efficiency of hydrogen was determined by the volume of the gas evolved and taken into account in the form of a constant average value.…”

“…There are many works dedicated to the influence of overpotential, electrolysis regime, concentration of the discharging ions and supporting electrolyte on the morphology of loose deposits [4][5][6][7][8][9][10][11]. The model description of the electrocrystallisation of dendritic deposits was proposed by different authors for both potentiostatic [2,3,12,13] and galvanostatic electrolysis conditions [14][15][16][17][18].…”

“…In most studies [4][5][6][7][8][9][10] the current efficiency of hydrogen was determined by the volume of the gas evolved and taken into account in the form of a constant average value. There is an article by a group of scientists [11] who associate the fact of the dendrite formation (particularly zinc) with the presence of hydrogen bubbles on the deposit-branching mechanism. A detailed research of the current efficiency of copper was performed in the work by Murashova et al [21], which introduced the 'differential current efficiency' concept.…”

Electrodeposition of Copper, Selenium, Indium, and Gallium on Molybdenum/Surface Oxides: Unary, Binary, Ternary and Quaternary Compositions

“…Hsu et al demonstrated that hydrogen bubbles directly affect the growth morphology and can make it possible to control the dendritic growth. 56 On analyzing the current variation during CA ( Figure 7A), it was interesting to see that In showed the highest current densities among the four unary systems. Open circuit potentials (OCP) showed most negative values in In(III) electrolyte ( Figure 7D).…”

<i>Operando</i> X-ray Fluorescence Imaging for Zinc-based Secondary Batteries

“…Among few operando methods to analyze the distribution of the zinc species, 5,6 X-ray fluorescence (XRF) imaging using a bright synchrotron X-ray source has advantages of elemental labeling, wide observation view and reasonably high spatial-and timeresolutions. 7 Especially, the XRF imaging in reflection geometry allows to capture the distribution of species of interest in a wide area of an electrochemical cell with rapidity, in contrast to the commonly used analytical methods in transmission geometry that is suffered from signal absorption in the electrolyte.…”