Apr 17, 2014
Lithium ion batteries: nanostructured composites improve storage properties
With its high theoretical capacity, natural abundance, low cost and environmental benignity, Fe3O4 is an appealing alternative anode material for lithium-ion batteries. However, similar to other transition metal oxides (MxOy), it has an extremely low intrinsic conductivity and poor structural stability during lithium ion (Li+) insertion or extraction. Reporting in Nanotechnology, researchers have investigated nano/micro-structured Fe3O4/rGO/CNT composites, which show remarkably improved Li+ storage properties, such as high capacity retention, excellent rate capability and outstanding cycling performance.
The unique properties of graphene, including good conductivity, high specific surface area and superior mechanical strength, make it an excellent reinforcing component in composites. Further introducing carbon nanotubes (CNTs) in a hierarchical nanostructure can not only prevent the restacking of graphene sheets, but also construct 3D conducting frameworks together with reduced graphene oxide (rGO) to promote rapid electron transport. As reported here, the rGO/CNT architecture plays a crucial role in the formation of Fe3O4 microspheres, because it creates a favorable micro-environment and suppresses the overgrowth of Fe3O4 microspheres during Ostwald ripening.
Li+ storage performances depend heavily on the structure and morphology of composite materials. To achieve desirable goals, researchers have to design and synthesize composite materials with more rational structures as well as tailored sizes and morphologies. This provides reinforced synergistic effects and structural hybridization within the stable nano/micro hierarchical structure. Combined with the advantageous interlinked ionic and electronic conducting networks, the as-synthesized Fe3O4/rGO/CNTs consequently exhibit superior Li+ storage performances.
The researchers, from Central South University in China, believe that the reported synthetic strategy could be applied to other MxOy/rGO/CNT composites with similarly fascinating Li+ storage performances for lithium-ion batteries. It could even be extended to other energy storage and conversion devices like supercapacitors and photocatalysts.
More information about the research can be found in the journal Nanotechnology 25 225401.
Energy storage team designs carbon-encapsulated Fe3O4 nanocrystals (Dec 2012)
Non-covalently functionalized graphene enhances thermal transport (Mar 2013)
3D nanostructured composite makes good battery anode (Oct 2013)
Nanotubes make for better lithium-ion batteries (Mar 2014)
About the author
Jinlong Liu is a MSc candidate at the College of Chemistry and Chemical Engineering at Central South University, supervised by Dong Qian. This group focuses on advanced materials with applications in energy storage, catalysis and sensors.