Abstract
Although Li-ion batteries are predominant in the actual battery market, they have reached their limits in terms of energy density. The ever-increasing demand of more energetic and powerful systems stimulated the research of new technologies. Lithium metal is the perfect candidate for high energy batteries because of its theoretical specific capacity, ten times higher than graphite, the current negative electrode in Li-ion batteries. However, the use of lithium metal as negative electrode promotes the growth of dendrites that can cause short-circuits and fire hazards.This research work was devoted to the study of two strategies aiming at modifying the electrolyte medium and/or the surface of the electrode in order to limit the formation of dendrites. These two approaches also have a strong influence on the so-called Solid Electrolyte Interphase (SEI), a passivation layer at the electrode/electrolyte interface, which was also studied. These strategies were then extended to sodium and potassium metal, innovating systems alternative to lithium currently under investigation for large-scale energy storage applications.For the two applied strategies, namely the use of highly concentrated electrolytes and the formation of a protective layer on top of the metallic electrode surfaces, the electrochemical depositions of lithium, sodium and potassium were improved. These improvements are attributed to the different SEI formed during the plating/stripping cycles, which are highlighted by ex situ, in situ or operando characterizations.Keywords : Li-metal batteries, metallic electrodes, dendrites, concentrated electrolyte, protective layer