Nanocarbon/metal hybrid materials for electrical and energy applications

Geon-Woong Lee

Electrical Materials Research Division

Korea Electrotechnology Research Institute (KERI), Changwon 51543, Korea

Conducting ink or paste are necessary to apply various energy and electronic devices such as secondary battery, supercapacitors, flexible display, and transistors. The metallic nanoparticle inks, mostly based on Ag and Au, are adequate solution processable materials satisfying the requirements such as low-temperature processability, high conductivity, and environmental stability.  The high cost involved in synthesizing Au, Ag nanoparticles, however, has overshadowed these advantages. Cu nanoparticles are considered to be a viable alternative in terms of their inexpensive chemical synthesis pathway and, in principle, low resistivity comparable to that of noble metals (Au, Ag). However, the presence of a surface oxide layer, even with thickness below a few nanometers, critically degrades the electrical properties of Cu nanoparticle-based conductive layers. Here we introduced environmentally stable Cu nanoparticle-based conductive fillers by covering the graphene layer. The electrical and mechanical properties of Cu/graphene-core/shell materials as well as environmetal stability are discussed. In particular, solution-processable graphene is possible for preparation of various electrodes with respect to energy storage devices due to its superior properties such as mechanical and chemical stability and high electrical conductivity. Production of highly conductive and concentrated reduced graphene oxide (rGO) is made possible by the modified oxidation of graphite, the shear-induced exfoliation and the presence of monovalent cation–π interactions in aqueous solution. The stable dispersion of rGO could be directly applicable for silicon-rGO complex as anode materials for lithium ion batteries. The highly conductive solution-processable rGO has exellent potential for the practical use of lithium ion battery to decrease volume expansion for silicon active materials.