Rigid‐tough Coupling of the Solid Electrolyte Interphase Towards Long‐Life Lithium Metal Batteries

A novel quasi-solid-state polymer electrolyte (QPE), was developed in situ by radical random polymerization of a cyclic carbonate-based monomer (CUMA) and a urea-containing monomer (CUEM). The symmetrical Li/Li cell with P(CUMA-CUEM)-QPE shows stable voltage profiles with a constant overpotential of ≈36 mV for more than 1600 h, superior to the results of most previously reported QPEs.

Abstract

Lithium metal batteries are highly pursued for energy storage applications due to superior energy densities. However, fast battery decay accompanied by lithium dendrite growth occurs mainly owing to solid electrolyte interphase (SEI) failure. To address this, a novel functional quasi-solid-state polymer electrolyte is developed through in situ copolymerization of a cyclic carbonate-containing acrylate and a urea-based acrylate monomer in commercial available electrolyte. Based on the rigid-tough coupling design of SEI, anionic polymerization of cyclic carbonate units and reversible hydrogen bonding formed using urea motifs on the polymer matrix can take place at SEI. This mechanically stabilizes SEI and thus helps achieve uniform lithium deposition behaviors and non-dendrite growth. Thus, the superior cycling performance of LiNi_0.6Co_0.2Mn_0.2O₂/Li metal batteries is promoted by the formation of compatible SEI. This design philosophy to build mechanochemically stable SEI provides a good example for realizing advanced lithium metal batteries.

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