Edge-Rich Graphene by Bimetallic Junction Coated on Highly Ordered Multi-Block Nanotubes for Anode in Lithium Ion Battery and Supercapacitors

Abstract

We demonstrate a promising strategy for enhancing performance of lithium ion battery and supercapacitors by increasing the edge densities of vertical graphene nanotubes. To control the density of graphene edges, we employ Ni-Au multi-block vertical nanotubes fabricated by anodic aluminum oxide (AAO) template-assisted electrodeposition as a designer substrate for graphene growth. The tubular structure synthesis is assisted by using the conducting polymer polyaniline (PANI) as a sacrificial core in the anodic aluminum oxide (AAO) nanochannels. The graphene edge density is tailorable by controlling the total number of bimetallic interfaces of alternating electrodeposited Ni and Au blocks. This edge generation of graphene relies on the distinct carbon solubility of Au and Ni under chemical vapor deposition (CVD). In lithium ion battery and supercapacitor applications, results show that the graphene edge densities heavily correlate to the capacitance. Graphene nanotubes with 18 bimetallic interfaces exhibit higher capacity and capacitance than those without interfaces. This experimental evaluation opens up a new way to significantly enhance the anode electrode and supercapacitor by creating high-density graphene edges on tailored bimetallic substrates.