Preparation of ultra-thin copper–aluminum composite foils for high-energy–density lithium-ion batteries through synergistic electroless plating and electroplating

Copper-aluminum composite foils have the advantages of excellent electrical and mechanical properties, lightweight, and low cost. However, overcoming the equipment limitations of physical preparation methods to produce ultra-thin copper-aluminum composite foils with outstanding properties has been a challenge. Herein, smooth-faced, dense, and tightly bonded copper-aluminum composite foils are prepared using a combination of electroless plating and electroplating. This process involves the use of tin and nickel as transition layers, followed by electroplating the copper-clad layer. Ultra-thin copper-aluminum composite foils with a copper layer thickness ranging from 0.5 to 7 μm and a minimum square resistance of 4.6 mΩ can be prepared with a mass of 36.7%-70% of that of pure copper foils of the same thickness. These foils are expected to be used in a variety of energy storage components that require extreme lightweight.