Ever-increasing energy needs and depleting fossil fuel resources require the search for sustainable energy alternatives. Batteries are crucial technology for the transition to a more sustainable energy supply. Magnesium batteries are considered one of the promising alternatives to lithium-ion batteries. The use of a magnesium metal anode allows us to achieve a higher gravimetric and volumetric capacity compared to the graphite anode used in lithium-ion batteries. Magnesium has a low reduction potential (-2.36 against SHE), which enables high voltage of battery cells. In addition, magnesium is significantly more abundant in the Earth's crust than lithium and also much cheaper. But in addition to many advantages, metallic magnesium has problems with surface passivation, because in contact with many substances a passive layer is formed on the surface, which is non-conductive and hinders the efficient loading and dissolution of metallic Mg. In recent years, a key shift has been made on the modification of the solvation shell of Mg$^{2+}$ ions in ether solvents by the addition of various additives. These additions change the solvation of the Mg$^{2+}$ cation and prevent the formation of a passive layer and enable efficient loading/dissolving of metallic Mg. Several scientific articles have been published on this topic in recent years.
In my thesis, I investigated the influence of various additives on Mg electrolyte based on magnesium bis(trifluorosulfonylimide) Mg(TFSI)$_2$ and magnesium trifluoromethanesulfonate Mg(OTf)$_2$. in diglyme (DGM). My main focus was on 3 additives from 3 different classes (alkyl phosphates, alkyl halides and ether-amino ligands). Electrochemical operation was characterized by classical galvanostatic plating/stripping and additional protocols aimed primarily at the passivation of loaded magnesium. I evaluated the electrochemical stability of magnesium electrolytes using linear voltammetry (LSV).
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