Regionally Localized Electrolyte Engineering via UV Crosslinking for Stable Ether-Carbonate Lithium Metal Batteries

초록

Electrolytes in Li metal batteries (LMBs) are employed primarily with ether- or carbonate-based, each offering distinct interfacial advantages yet facing critical compatibility challenges. Ether-based electrolytes exhibit high reductive stability toward Li metal but suffer from oxidative decomposition at high-voltage cathodes. Conversely, carbonate-based electrolytes maintain stability at the cathode but promote uneven SEI formation and dendritic lithium growth. Here, a regionally localized electrolyte (RLE) concept-an interface-specific electrolyte design that spatially separates electrolyte functions is introduced. An ether-rich electrolyte layer is locally immobilized on the lithium surface via a UV-curable trimethylolpropane ethoxylate triacrylate (ETPTA) polymer matrix, while the bulk electrolyte remains carbonate-based, enabling each to perform optimally at its respective interface. By tuning the ETPTA content, a balance between mechanical robustness and ionic mobility was achieved. Both experimental and theoretical analysis confirm that the optimized RLE anode promotes Li+-selective transport, effectively suppresses parasitic side reactions, and lowers interfacial overpotential. This leads to a more uniform Li deposition, and markedly improved cycling performance. Moreover, RLE facilitates sustained ion-transfer stability and the formation of a homogeneous, LiF-rich SEI layer. Overall, the RLE approach offers a practical electrolyte design framework to harmonize electrode interfaces and enhance the interfacial stability of high-energy LMBs.

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