Role of complex formation in metal deposition - a theoretical study

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Metal deposition is a fundamental process in electrochemistry and of great practical importance. Until very recently, the kinetics of this class of reactions was not understood at an atomic level, so that some colleagues spoke of the enigma of metal deposition. The applicants have solved this enigma for the case of small, univalent metal ions in aqueous solutions, but multivalent ions remain a puzzle. For energetic reasons electrons can only be transferred one at a time, but the energies of the intermediate solvated ions are almost always so high, that the first electron transfer would be highly unfavorable. In accord with much experimental evidence we surmise that the energies of these intermediate states are lowered by the formation of metal complexes, typically with anions. We want to investigate this mechanism by a combination of density functional theory, molecular dynamics, and our own theory, which must be extended to include complex formation. Non aqueous solvents often offer a wider potential range for metal deposition than water, and will therefore be at the center of our investigations.Starting from the relatively simple case of the monovalent lithium ion, we shall move on to more complex reactions like copper deposition, and in particular to magnesium deposition from etherial solutions, which is important for magnesium batteries. Throughout this project we shall cooperate with a group of international renown, which investigates these processes experimentally. We are confident that our project will provide a fundamental understanding of a class of electrochemical reactions which at present is the focus of battery research. The two applicants have been cooperating for more than a decade, and form an experienced team with complementing expertise.