An ionic liquid-based composition for protecting lithium metal anodes in a lithium-based electrochemical energy storage systeme, comprising a polymerizable ionic liquid (or ionic liquid monomer), the cation or the anion of which carries at least one polymerizable function, a non-polymerizable ionic liquid, an ionic liquid of the “crosslinker” type, the citation or the anion of which carries at least two polymerizable functions, and a lithium salt.
The ionic liquid-based polymer composition coated as such on the lithium surface, even if it is swelling with liquid electrolyte, protects the lithium against a constant electrolyte consumption and formation of unstable solid-electrolyte interphase (SEI), which is continuously forming on a bare lithium surface. The growing of dendrites is retarded with such ionic liquid-based polumer composition protection.