Effect of Y3+on microstructure optimization and performance enhancement of ultra-thin electrodeposited copper foil

Ultra-thin copper foil is critical for high-density circuits and lithium-ion battery current collectors, yet surface roughness, brittleness, and inhomogeneous grains limit performance. This study demonstrates that rare-earth yttrium ions (Y 3+ ) in acidic copper sulfate electrolyte optimize microstructure and enhance properties of electrodeposited copper foil. At 0.6 mg/L Y 3+ , grain refinement (0.4–0.9 μm), intensified (220) plane (T C  = 1.85), and minimized surface defects were achieved via adsorption-mediated growth inhibition. The optimized foil exhibited 63 % lower corrosion current density (0.47 μA/cm 2 ) and 3.5 times higher charge transfer resistance versus Y 3+ -free counterparts. Y 3+ suppresses dendritic growth while promoting preferential orientation, reconciling high strength, corrosion resistance, and interfacial stability. This work provides a novel rare-earth-based strategy for manufacturing high-performance copper foils in advanced electronics and energy storage.