Twin-functional graphene oxide: compacting with Fe₂O₃ into a high volumetric capacity anode for lithium ion battery

Graphene oxide (GO) shows very unique twin functions, both as hard and soft templates, in the production of highly solid Fe₂O₃ microspheres. The microsphere is a very dense aggregation of nanosized primary particles and represents an important advance in energy storage materials with high volumetric performance. GO as a hard template is responsible for the precursor nucleation in the formation of the primary nanoparticles (NPs), and meanwhile, as a soft template, manages the densification of these NPs to form a secondary solid and compact microsphere. Together with three-dimensional interconnected conductive graphene network formed spontaneously, the highly solid Fe₂O₃ microspheres exhibit an excellent rate performance and more importantly, a super high volumetric capacity of about 1200 mA h cm⁻³. This work shows a promising approach for the densification of nanostructures and promotes the practical applications of low density nanomaterials in real energy storage devices.