Preparation of Gr-Reinforced Cu Foil: A Challenge to Ultrathin Thickness

Abstract

A layered Cu/Gr/Cu ultrathin foil via a one-step electrochemical route A layered structure has a better effect on improving performance of the graphene (Gr)-reinforced composites due to its unique two-dimensional structure and excellent properties. In this work, a novel “one-step” electrochemical route was proposed for synthesizing the Gr-reinforced ultrathin copper (Cu) foil with high performance. The process includes: 1) A loose graphene oxide (GO) membrane, was prepared by electrophoresis deposition (EPD), that allows Cu ions passing through; 2) According to the difference of Cu deposition potential on different substrates, a potential step was designed for electrodepositing Cu successively on both sides of the GO membrane, i.e., the bottom Cu layer forms under low over-potential, while the top Cu layer forms under high over-potential. The experimental results show that the foil thickness reaches to as thin as 4-5 μm, and the tensile strength is almost twice as large as that of pure Cu foil. This process is simple, controllable and possible mass production, and expected to further practical applications in fields of Cu clad plate, printed circuit board and lithium-ion battery cathode collector system for saving raw material and also the space. In addition, this work proposes a new idea for preparing the layered composites via electrochemical route. A Cu-(CNTs+Gr) composite ultrathin foil via electrodeposition The incorporation of nano-reinforcement, such as carbon nanotubes (CNTs) and graphene (Gr), into copper (Cu) matrix via electrodeposition is a promising method to improve its comprehensive property. However, the challenge is to achieve a uniformly suspended electrolyte with these reinforcements or surfactant due to their inferior dispersibility. In this work, we report a process to produce a kind of high performance Cu-(CNTs+Gr) composite foil by using hybrid self-dispersing reinforcement CNTs+Gr via a direct current (DC) electrodeposition, which further results in an ultrathin foil reach to the thickness as low as 4 μm. In this process, firstly, the precursor graphene oxide (GO) with amphipathicity acts as a surfactant-like substance and disperses CNTs uniformly through the π-π bonding in-between GO and CNTs in the copper sulfate electrolyte. Then, GO is reduced into Gr during electrodeposition, and the synergistic effects of CNTs and Gr play a key rule to improve the ultrathin Cu-(CNTs+Gr) composite foil’s properties, including tensile strength up to 436 MPa, inoxidizability and superior electrical conductivity. This work provides a possibility to have mass-production of Cu foil as thin as 4 μm in industry and broad applications in the future.