Enhancing stable LiF-rich interface formation of polyester based electrolyte using fluoroethylene carbonate for quasi-solid state lithium metal batteries

Abstract

Lithium metal batteries (LMBs) have attracted worldwide attention for next-generation energy storage systems. However, lithium metal anode is prone to harmful reactions with traditional liquid electrolytes (LEs) leading to oxidative decomposition. Especially uncontrolled lithium dendrite growth and unstable solid electrolyte interface (SEI), which often lead to serious capacity attenuation and safety problems, hindering the development of LMBs. Herein, a solvation structure engineering strategy based on tuning intermolecular interactions is proposed to design polymer electrolyte. The interface additive of fluoroethylene carbonate (FEC) was introduced into the electrolyte precursor. By using FEC to modify the solvation structure of the electrolyte, an enhanced LiF-rich SEI was engineered to regulate the electrode/electrolyte interface composition and prevent continuous reactions on the lithium metal surface. Li|PHTL-10%FEC|Li symmetrical cell demonstrated cycling of 200 h at 0.2 mA cm−2, while matching LiFePO4 cathode exhibited stable cyclic performance. This study enables long cycling performance and provides a guiding principle in electrolyte design for LMBs.