Synthesis of stretchable hybrid copper films via nanoconfinement

Abstract

Flexible ultrathin copper films are desired for use as flexible electromagnetic shielding, smart clothing, and energy storage devices. The fabrication of such films can be realized through plasma assisted surface coating on flexible polymer thin films. Unfortunately, the use of plasma treatment leads to substantial damage to the polymer substrates, which is particularly serious for ultrathin films. Here, we report the fabrication of stretchable, ultrathin, yet ultrastrong hybrid copper films via simple nanoconfinement. The hybrid films are prepared by the conformal electroless deposition of copper nanoparticles on nanofibrils of ultrastrong ultrahigh molecular weight polyethylene (UHMWPE) membranes. These flyweight hybrid copper films (0.3 mg cm⁻²) possess a high mechanical strength of 390 MPa, 26% larger than pure copper foils; a low resistivity of 5 × 10⁻⁸ Ω m at a cyclic extensional strain of 1%; and macroscopic shape recovery after applying a biaxial extension strain of 10%. The shape recoverability and the high mechanical strength of the hybrid copper film were derived from the unique nanofibrous network of the ultrastrong UHMWPE substrate. As an application, we fabricated a lithium-ion battery using the CuPE as the current collector at the graphite anode and observed a near 100% and 10% increase in energy density concerning the total mass and total volume of the anode, respectively.