Synergistic Interfacial Engineering of ZnO-Modified Cu Current Collectors Using Lithium Trithiocyanurate for Stable Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries (AFLMBs) promise high-energy-density, cost-efficient storage by removing excess lithium at anode side, yet their practical use is limited by uncontrolled Li nucleation, continuous Li loss, and unstable Cu interfaces. We report a synergistic interfacial strategy using a lithiophilic ZnO-modified Cu current collector with a lithium trithiocyanurate (Li-TCA) coating to stabilize Li deposition and regulate Li⁺ transport on the solid electrolyte interphase (SEI). The ZnO bottom layer provides uniform nucleation sites, lowering the Li nucleation barrier, while the Li-TCA top layer acts as a Li reservoir and interfacial regulator, mitigating early Li depletion and enhancing stability. Optimized 5%Li-TCA@60%ZnO@Cu anodes exhibit markedly improved Li reversibility and reduced polarization, delivering an ultralow initial plating/stripping overpotential of 12.8 mV, compared to 40.9 mV for ZnO@Cu and 76.1 mV for bare Cu. Paired with high-mass-loading LiFePO₄ cathodes (~17 mg cm⁻²), these anode-free full cells show enhanced initial Coulombic efficiency and cycling stability, retaining 56.2% capacity after 100 cycles versus 47.8% and 34.6% for ZnO@Cu and bare Cu, respectively. scanning electron microscopy and X-ray photoelectron spectroscopy analyses confirm uniform Li deposition, suppressed dead Li, and stabilized SEI, validating the dual-function design. This scalable strategy addresses Li nucleation, SEI stability, and Li inventory, offering a promising route toward practical AFLMBs.