(491c) In Situ Activation of Nitrogen-Doped Graphene-Based Materials Anchored on Graphite Foam for High-Performance Energy Storage

Authors: 
Yue, H., Sichuan University
Liu, C., Sichuan University
Contact interface between the active materials and the current collector is essential for electron transfer rate and the mechanical properties of an electrode. With a traditional drop-casting electrode preparation method, the nano-sized active materials should mix with the nonactive and nonconductive binder, thus inevitably affect the total electrode resistance. Activation of graphene-based materials (e.g. graphene, carbon nanotube) by KOH can rebuild the crystalline structure to obtain continuous interface contact to facilitate electron transfer, while the molten KOH can act as the filler to enlarge the interlayer space to increase the electrolyte ion transfer rate.

Here, three-dimensional free-standing nitrogen-doped porous graphene-based materials/graphite foam composites (aNG/GF) were fabricated via in situ activation of nitrogen-doped graphene-based materials on highly conductive graphite foam (GF). During activation, the molten KOH reacts with the carbon to generate nano-holes as well as to rearrange the carbon, yielding a distribution of meso- and micro-pore channels and increases the specific surface area. After in situ activation, intimate â??sheet contactâ?? was observed between the graphene sheets and the GF. The â??sheet contactâ?? produced by in situ activation is found to be superior to the â??point contactâ?? obtained by the traditional drop-casting method, and facilitates electron transfer. Due to the intimate contact as well as the abundant nano-holes and channels, the aNG/GF electrodes can exhibit high electron and electrolyte ion transfer rate, which is of great important for high-performance energy storage devices. The aNG/GF electrodes can deliver high gravimetric capacity and volumetric capacity with respect to the whole electrode mass and volume (including the active materials and the GF current collector). Furthermore, the tailored contact interface and the unique micro-structure could guarantee a high rate performance of the electrode even under ultrahigh current density, indicating its promising use as a high-rate LIB anode.