In Situ Polymerization-Enabled Facile Electrode Interface in Solid-State Lithium–Metal Batteries

Here, a ceramic–polymer composite membrane consisting of P(VDF-HFP), LiTFSI, and a high-entropy rhombohedral NASICON-structured ceramic filler Li1.3Al0.1Sc0.1Y0.1Sn1.7/3Zr1.7/3Ti1.7/3(PO4)3 was employed as the solid electrolyte in the batteries. Further, the facile electrode interface was engineered via ring polymerization of 1,3-dioxolane (DOL) containing different lithium salts (LiTFSI, LiFSI, and LiDFOB) catalyzed by a LiPF6 salt. The synergistic effect of different salts provided a robust interphase at the lithium metal interface, enabling stable lithium plating/stripping in Li|Li coin cell configurations with a critical current density of ∼1 mA cm–2 at room temperature. The in situ polymerized matrix also facilitated the formation of potential lithium-ion conduit channels at the cathode side and the electrolyte–electrode interface, thereby mitigating key transport limitations that hinder the performance of conventional polymer electrolyte-based solid-state batteries. The Li|LiFePO4 coin cell configuration demonstrated excellent cyclability with a discharge capacity of 107 mAh g–1 after 500 cycles at 1C.