Exploring the mechanisms and interfacial processes of metal electrodeposition

Electrodeposition of multivalent metal cations in nonaqueous solvents is ultimately more difficult compared to aqueous systems. This is due to lower conductivity and a smaller library of soluble electrolytes. In many cases, synthesis procedures are required to obtain functional electrolytes. Comparison of these systems to aqueous counterparts is therefore very challenging. In some cases, the solvent itself can be used as another platform for side reactions to occur. Magnesium organohaloaluminate electrolytes in a THF solvent oxidize the solvent to γ-butryolactone (GBL). This conversion slowly degrades the active electrolyte and causes films of organic matter to build on the electrode surface as the magnesium metal is deposited and redissolved over several cycles. A decrease in the reported coulombic efficiency (i.e. the amount of charge removed from the surface to the amount deposited) is also observed for both organohaloaluminates studied. In conjunction, the mass removed to the mass deposited is always above 90% efficient. This suggests that uncharged mass is consistently deposited along with magnesium in later cycles. Given this, the stability and lifetime of the organohaloaluminates is lower than previously reported. When electrodepositing other multivalent cations such as copper or zinc, information regarding the general mechanism of the nucleation and growth can be gleaned by observing chronoamperometric data at early times in a potential step experiment. When observed in an aqueous environment, copper metal in a CuSO4 electrolyte deposits according to an instantaneous model at pH 3 and a progressive model at pH 1. In a nonaqueous environment, a similar system of CuCl2 shows instantaneous nucleation behavior. A direct comparison is not available due to the insolubility of CuSO4 in acetonitrile and copper deposition in water using CuCl2 is too quick to be observed.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2016

Author dc:creator

• Spatney, Russell Leonard

Contributors dc:contributor

• Gewirth, Andrew A.

• Electrodeposition
• Magnesium

Statement dc:rights

• Copyright 2015 Russell Spatney

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/89053

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/89053