Bifunctional lithiophilic-lithiophobic AlF3/LiF interlayer via in-situ construction for stabilizing solid-state battery interfaces

The advent of solid-state lithium-ion batteries has made it possible to achieve high energy density and enhanced safety in energy storage systems. However, commercialization has been hindered by interfacial contact deterioration between lithium metal and the solid-state electrolyte, coupled with electron leakage issues. Interfacial issues fundamentally govern the battery's capability for stable and sustained energy conversion, while also determining the likelihood of lithium dendrite propagation and growth. Consequently, a lithiophilic-lithiophobic dual-functional SEI layer (LiF/AlF 3 ) is constructed from an AlF 3 -PVDF-HFP organic-inorganic composite interlayer in this research (named CPEA3). The LiF generated via in situ reaction between AlF 3 and metallic lithium, characterized by high electron insulation property and high interfacial energy toward lithium, effectively suppresses the nucleation and growth of lithium dendrites. Simultaneously, leveraging the high adhesion energy of AlF 3 to lithium effectively stabilizes interfacial contact during lithium stripping processes, thereby preventing delamination-induced interfacial polarization. Therefore, the improved Li symmetric cells demonstrate an ultrahigh critical current density (3.0 mA cm −2 ) and remarkable cycling stability exceeding 2,800 hours at 0.1 mA cm −2 . Notably, the Li|CPEA3/LLZGO/CPEA3|LiFePO 4 configuration demonstrates substantial long-term cycling stability with 95.1% capacity retention after 600 cycles at 0.5 C. This work provides an effect stagy to suppress side reactions at the electrode/electrolyte interface and impede lithium dendrite in solid-state battery penetration through the construction of an intermediate passivation layer.