Abstract
In this work, we studied the effect of additions of decahydronaphthalene (decalin) and its derivative, perfluorodecalin (octadecafluorodecalin), on the deposition and dissolution of lithium metal, including dendrite formation, at the anodes of secondary lithium power sources in an electrolyte based on lithium hexafluorophosphate and a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC). The study was carried out using the methods of current transients and electrochemical impedance. The results showed that, in contrast to traditional cationic surfactants cetyltrimethylammonium bromide and hexadecylpyridinium bromide, which we studied earlier, decalin and perfluorodecalin demonstrate specific interaction with the surface of the lithium electrode. Moreover, the interaction with decalin is so strong that it actually blocks the processes of both deposition and anodic dissolution of lithium at the surface of the lithium electrode. The interaction of perfluorodecalin with the lithium surface turned out to be weaker. As a result, perfluorodecalin does not interfere with the cycling of the metal lithium anode, but at the same time shows an inhibitory effect on the dendrite formation. In the electrolyte with the addition of perfluorodecalin, lithium anode was able to undergo more than 80 charge-discharge cycles with a Coulomb efficiency of 70–80%, while without the additive, the number of cycles was less than 40, and the Coulomb efficiency was 60% or lower.