3D heterostructured architectures of Co3O4 nanoparticles deposited on porous graphene surfaces for high performance of lithium ion batteries

Control of structure and morphology in electrode design is crucial for creating efficient transport pathways of ions and electrons in high-performance energy storage devices. Here we report the fabrication of high-performance anode materials for lithium-ion batteries based on a 3D heterostructured architecture consisting of Co3O4 nanoparticles deposited onto porous graphene surfaces. A combination of replication and filtration processes - a simple and general method - allows a direct assembly of 2D graphene sheets into 3D porous films with large surface area, porosity, and mechanical stability. The polystyrene spheres are employed as sacrificial templates for an embossing technique that yields porous structures with tunable pore sizes ranging from 100 nm to 2 mm. Co3O4 nanoparticles with high-energy storage capacity can be easily incorporated into the pore surfaces by a simple deposition strategy, thereby creating a 3D heterogeneous Co3O4/graphene film. In particular, we exploit the 3D Co3O4/graphene composite films as anode materials for lithium ion batteries in order to resolve the current issues of rate capability and cycling life. This unique heterogeneous 3D structure is capable of delivering excellent Li+ ion storage/release and displays the following characteristics: a high rate capability of 71% retention even at a high current rate of 1000 mA g(-1) and a good cycling performance with 90.6% retention during 50 cycles. The versatile and simple nature of preparing 3D heterogeneous graphene films with various functional nanoparticles can be extended to overcome the major challenges that exist for many electrochemical devices.