Graphene–Nanotube–Iron Hierarchical Nanostructure as Lithium Ion Battery Anode

Abstract

In this study, we report a novel route via microwave irradiation to synthesize a bio-inspired hierarchical graphene--nanotube--iron three-dimensional nanostructure as an anode material in lithium-ion batteries. The nanostructure comprises vertically aligned carbon nanotubes grown directly on graphene sheets along with shorter branches of carbon nanotubes stemming out from both the graphene sheets and the vertically aligned carbon nanotubes. This bio-inspired hierarchical structure provides a three-dimensional conductive network for efficient charge-transfer and prevents the agglomeration and restacking of the graphene sheets enabling Li-ions to have greater access to the electrode material. In addition, functional iron-oxide nanoparticles decorated within the three-dimensional hierarchical structure provides outstanding lithium storage characteristics, resulting in very high specific capacities. The anode material delivers a reversible capacity of ~1024 mA · h · g(-1) even after prolonged cycling along with a Coulombic efficiency in excess of 99%, which reflects the ability of the hierarchical network to prevent agglomeration of the iron-oxide nanoparticles.

Microwave synthesis of nitrogen-doped carbon nanotubes anchored on graphene substrates

“…Comparing the lithium-ion capacity of our 3-D G-Fe@NCNT composites with iron-decorated graphene (synthesized by our previously reported doughnut method [31]), an almost threefold increase in capacity retention throughout the $146 cycles can be observed indicating that the presence of CNTs not only prevent the restacking of graphene but also circumvent the aggregation of Fe nanoparticles on cycling. Additionally, the presence of nitrogen moieties on the CNTs creates defects in the walls of nanotubes through which lithium ions can diffuse [47] and adhere to the interwall spaces, thereby making the observed lithiumion capacity one of the highest when compared to previously reported graphene-CNT-iron hybrids [32].…”

“…Besides, at high temperatures commonly encountered in the CVD growth of CNT, the chemical interface between the graphene and catalyst may be thermally driven off, causing extensive debonding of catalyst particles from the graphene substrate, which may lead to falling off of CNT. There are some reports on the microwave synthesis of CNTs anchored on graphene substrate either by premixing of microwave-synthesized graphene with CNT [28] or by in situ synthesis of CNTs using expensive ionic liquid precursors and palladium catalysts [29], or by the pop-tube technique [30][31][32]. However, in these reported techniques, only pristine CNTs are synthesized, whereas it is well known that heteroatom-doped carbon nanostructures possess distinct advantages in energy storage applications such as lithium-ion batteries [33], supercapacitors [34], etc.…”

Self-assembled porous MoO2/graphene microspheres towards high performance anodes for lithium ion batteries

“…The functional (eCOOH and eOH) groups present in graphene oxide (GO) act as a nucleation site for metal oxides, which facilitates via strong electrostatic bond during hybrid structure formation. Graphene, composite with metal oxide nanostructures of different dimensionality such as zero dimensional (0D) nanoparticles, one dimensional (1D) nanotubes and two dimensional (2D) nanoplates or nanosheets, serves as an excellent support for increasing the electrical conductivity and buffering large volume change of electrode [15,16].…”

High lithium anodic performance of highly nitrogen-doped porous carbon prepared from a metal-organic framework

“…13), graphene (approximately 568 mA h g À 1 ) (ref. 14) and carbon nanotube and graphene composites 15,16 . In addition, partially graphitized porous carbon is a class of emerging materials with promising chemical properties for LIBs due to their relatively low cost, high conductivity and porous structure, which make them very attractive materials.…”