Bio-inspired, nitrogen doped CNT-graphene hybrid with amphiphilic properties as a porous current collector for lithium-ion batteries

Carbon-based materials have been proposed as current collectors for lithium ion batteries (LIBs), however few of them have successfully integrated sp2 carbon and reach in sp3 carbon into one monolithic structure: in a way that sp2 carbon is responsible for electron transfer and sp3 carbon is capable for a high loading of active materials. Here we report an in-situ growth of a nitrogen-doped carbon nanotube (NCNT) on a three-dimensional (3D) graphene network. The proposed structure (NCNT-3DG) is a bio-inspired nanomaterial with a design of a “natural forest”. The in-situ growth of NCNT on 3D graphene guarantees a fast electron transfer between NCNT and 3DG. The hydrophilic nature of NCNTs insures a high loading of the active materials, such as Li4Ti5O12 (LTO). The designed LTO-NCNT-3DG electrode achieves an active materials loading of 74 wt% of the overall electrode mass, compared to about 20 wt% on traditional metal foil and 55 wt% on other reported carbon current collectors. Such a hybrid electrode delivers a higher specific capacity of 158 mAh g−1 at 5C. The specific capacity retains 94% after 2000 cycles at 10 C. The proposed NCNT-3DG current collector is a novel strategy for fast charging LIBs.