A multifunctional artificial protective layer for producing an ultra-stable lithium metal anode in a commercial carbonate electrolyte

Uncontrollable lithium (Li) dendrite growth and continuous side reactions with a carbonate-based electrolyte seriously restrict the use of Li metal anodes. We report a very tough multifunctional artificial protective (MAP) layer formed on a Li metal anode that is ultra-stable in the normally used commercial carbonate electrolyte. The MAP layer is prepared by thein situphotopolymerization of pentaerythritol tetraacrylate (PETEA) and poly(ethylene glycol)diacrylate (PEGDA) in a framework of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) incorporated with graphene oxide (GO). There are two aspects to the functionality of this MAP layer. It has excellent compatibility with the carbonate electrolyte because of the similar chemical structure of the ester group, giving it a high ionic conductivity, and induces the formation of a unique solid electrolyte interphase (SEI) containing organic components and LiF, which has a good chemical stability with the carbonate liquid electrolyte to suppress Li dendrite growth and side reactions. A symmetric battery with the MAP coated Li (MAP-Li) anode steadily cycles for over 1100 h at 1 mA cm⁻²in a carbonate liquid electrolyte. The work provides a way to obtain a stable Li metal anode in a practical carbonate electrolyte.