(759b) Hierarchical Porous Reduced Graphene Oxide As High-Performance Anode for Li-Ion Batteries

Lithium-ion batteries (LIBs) are modern energy storage devices that have shown substantial promise in solving the global energy demand. Among possible electrode materials, graphene has emerged as one of the foremost candidates, due to their unique material properties. A scalable and cost-effective approach for fabricating graphene-based electrode materials involve the use of graphene oxide (GO) obtained via direct exfoliation of graphite. However, due to the van der Waals interactions and high aspect ratio of GO sheets, GO sheets can easily restack and form a bulk graphite-like structure during conventional fabrication process. The restacking of graphene sheets result in significant loss of usable Li-insertion sites, and consequently, a decrease in specific capacity and rate capability of the electrode. Therefore, it is necessary to develop synthesis strategies that preserve graphene interlayer space and Li-insertion sites. In this work, with the assistance of micro oil-gel as a template, we report the design of hierarchical macro/meso-porous reduced graphene oxide (RGO) materials as anodes in LIBs. Macropores with diameter ~200nm could serve as “highway” for Li ion transport, while mesoporous structure along the macropore walls enhance the overall surface area (~276 m²/g) of RGO anodes and further shorten the overall Li ion transport length. The resulting RGO anode material shows a high reversible capacity (~720 mAh/g at 0.2C) and high rate capability (~160 mAh/g at 20C). Furthermore, the process to fabricate such hierarchical structures is novel, facile and scalable, and opens up a promising strategy to develop enhanced electrodes for lithium ion batteries.