In Situ Construction of Composite Artificial Solid Electrolyte Interphase for High-Performance Lithium Metal Batteries

Lithium metal is considered as the most promising anode material for high energy density secondary batteries due to its high theoretical specific capacity and low redox potential. However, poor interfacial stability and uncontrollable dendrite growth seriously hinder the commercial application of Li metal anodes. Herein, we constructed a composite artificial solid–electrolyte interphase (ASEI) utilizing the in situ reaction between polyacrylic acid (PAA)/stannous fluoride (SnF2) and lithium metal, which spontaneously generates LiPAA, LiF, and Li5Sn2 alloys. The in situ formed LiPAA as a flexible matrix can accommodate the volume change of the lithium anode. Meanwhile, LiF and Li5Sn2 play the roles for improving the mechanical properties and boosting Li-ion flux in the interfacial layer, respectively. Benefiting from the ingenious design, the PAA–SnF2@Li anodes remain stable and dendrite-free morphology in symmetric cells for over 2000 h and exhibit excellent cycling stability in high-area loading (10.52 mg cm–2) Li||LiFePO4 full cells with a N/P of 1.68, which endures only 0.11% average capacity decay per cycle in 200 cycles. This simple and low-cost method supplies a route for the commercial application of lithium metal anodes with fresh eyes.