Scalable fabrication of ultrathin LiIn@Cu composite anodes via roll-to-roll dip coating for high-energy-density batteries

Scalable roll-to-roll dip coating fabricates ultrathin LiIn@Cu anodes. • Indium additive enhances molten lithium wettability on copper current collectors. • In₃Li₁₃ alloy phases act as lithiophilic sites to guide uniform Li deposition. • Pouch cell shows impressive flexibility under folding and unfolding conditions. Lithium metal anode is essential for next-generation high-energy-density batteries, yet its practical implementation is severely hindered by the challenges in manufacturing ultra-thin foils (< 50 μm) and the safety concerns associated with dendrite growth. In this study, we introduce a scalable and efficient roll-to-roll dip coating method to fabricate an ultra-thin (20 μm) LiIn@Cu composite anode. Copper current collector is lithiumphobic and hard to cast molten lithium. By adding a small amount of indium, it significantly improves the wettability of molten lithium on copper. The resulting anode demonstrates enhanced adhesion, along with abundant lithiophilic In₃Li₁₃ alloy phases that direct uniform lithium deposition. Electrochemical tests demonstrate that the LiIn@Cu anode delivers superior cycling stability for over 350 h in symmetric cells. Notably, when paired with NCM811 cathode at a low negative-to-positive (N/P) ratio of ~3, the full cell retains 85% capacity after 90 cycles, offering a promising strategy for the industrial-scale production of robust lithium metal anodes.