Large scale patternable 3-dimensional carbon nanotube-graphene structure for flexible Li-ion battery

There has been strong interest in flexible, lightweight and reliable rechargeable batteries to meet the requirements of today's portable devices. To build such flexible rechargeable batteries with high efficiency, new architectures for current collectors need to be developed. The porous 3-dimensional (3D) electrode architecture has been proposed to increase the efficiency of a Li-ion battery by using its higher surface area, shorter diffusion path and higher volumetric capacity than those of 2D electrodes. Herein we fabricated an array structure of 3D multiwall carbon nanotubes (MWCNTs)-graphene on transparent and flexible polyethylene terephthalate (PET) film through a simple lamination process. The transferred 3D column structure of MWCNTs onto graphene-PET film showed structural integrity and low contact resistance at high angle bending. The new flexible 3D MWCNTs-graphene-PET electrode yielded excellent C-rate capability and specific capacity with high Coulombic efficiency of over 99%. The novel 3D MWCNTs-graphene nanostructure fabricated on flexible film could provide a wide range of applications in next-generation flexible and light weight batteries and energy storages.