Enhancing\nQuasi-Solid-State\nLithium-Metal Battery\nPerformance: Multi-Interlayer, Melt-Infused Lithium and Lithiophilic\nCoating Strategies for Interfacial Stability in Li||VS<sub>2</sub>‑DSGNS-LATP|PEO–PVDF||NMC622-Al<sub>2</s

The\ndevelopment of quasi-solid-state lithium metal batteries\n(QSSLMBs)\nis hindered by inadequate interfacial contact, poor wettability between\nelectrodes and quasi-solid-state electrolytes, and significant volume\nchanges during long-term cycling, leading to safety risks and cataclysmic\nfailures. Here, we report an innovative approach to enhance interfacial\nproperties through the <i>in situ</i> construction of QSSLMBs.\nA multilayer design integrates a microwave-synthesized Li<sub>1.3</sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> (LATP)\nceramic electrolyte, which is surface-coated with a lithiophilic conductive\nink comprising VS<sub>2</sub> and disulfonated functionalized graphene\nnanosheets (VS<sub>2</sub>-DSGNS) using a low-cost nail-polish binder.\nSubsequently, a few drops of LiPF<sub>6</sub> in EC/DMC liquid electrolyte\n(LE) are impregnated into the uncoated side of the LATP surface. The\nquasi-solid-state electrolyte pellet of LATP-VS<sub>2</sub>-DSGNS\nsurface was allowed to be in contact with the molten Li and held until\nLi flowed into the LATP-VS<sub>2</sub>-DSGNS surface completely <i>via</i> a “melt-infusion strategy” as an anode\nside. Additionally, a heterogeneous polymer matrix consisting of poly(ethylene\noxide) (PEO) and poly(vinylidene difluoride) (PVDF) as a polymer interlayer\nis fabricated using a solution casting technique for improving the\nwettability between the LE impregnated side of LATP and cathode, to\nenhance overall charge transfer kinetics. The assembled symmetric\ncells, Li||LATP-VS<sub>2</sub>-DSGNS||Li and Li||PEO–PVDF/LE-LATP||Li,\ndemonstrate high lithium-ion conductivities of 3.69 × 10<sup>–4</sup> and 1.02 × 10<sup>–3</sup> S cm<sup>–1</sup>, respectively, with impressive lithium-ion transfer numbers of 0.84\nand 0.93 at 25 °C. Both cells exhibit a highly reversible lithium\nstripping/plating cycling process for over 600 h, with minimal voltage\npolarization of 10 and 31.6 mV, across a broad redox window (−1\nto 6 V), effectively inhibiting lithium dendrite formation. Furthermore,\nthe combination of a surface-modified Al<sub>2</sub>O<sub>3</sub> dry-coated,\nhigh-nickel NMC622 cathode with the PEO–PVDF|LATP-VS<sub>2</sub>-DSGNS||Molten-Li architecture in a CR2032 coin-type full-cell delivers\na galvanostatic discharge capacity of 130.6 mAh g<sup>–1</sup> at a 1C rate after 200 cycles, achieving 84.3% capacity retention,\nthereby demonstrating substantial reduction in interfacial resistance\nand enhanced stable battery performance of QSSLMBs.