Syntheses of three-dimensional carbon nanostructures and their applications to battery and EMI shielding

Abstract

This research is to develop innovative method to synthesize three-dimensional self-assembled nano-structures based on ‘defect engineering’ using intentional defects to grow another nanostuructrures on graphene. It can be applied to engineering applications such as lithium ion battery anode, and EMI shielding film. First, the multilayered graphene-carbon nanotube-iron oxide 3D heterostructure(3D G-CNT-$Fe_2O_3$) demonstrates excellent EMI shileidng effectiveness over 130 dB due to strong synergy from multilevel EMI shiled-ing. Second, the bio-inspired 3D graphene-nanotube-iron hierarchical nanostructrue(hieararchical 3D G-CNT-Fe) delivers a reversible capacity of ~1,024 mAh/g even after prolonged cycling along with a cou-lombic efficiency in excess of 99%, which reflects the ability of the hierarchical network to prevent ag-glomeration of the iron-oxide nanoparticles. Third, we report a nanohole-structured, iron oxide-decorated and gelatin-functionalized graphene aerogel (D-N-GGA) for high rate and high capacity Li-ion anode. The D-N-GGA nanostructure provides highly conductive networks and short diffusion lengths for lithium ion transport. Furthermore, 3D carbon nanomaterials with N doped surface from gelatin can provide more active sites for Li storage. And the gelatin acted as a ‘glue’ binding the graphitic particles together. As a result, the obtained D-N-GGA nanostructure delivered a reversible capacity of 924 mAh/g even after 40 cycles along with a coulombic efficiency in excess of 99%. Especially, even after 65 cycle with variable current density with 100-800 mA/g, the discharge capacity returned to 1,096 mAh/g, which indicated a very stable cycle performance.