Advanced Functional Materials, Vol.26, No.4, 577-585, 2016
CaO-Templated Growth of Hierarchical Porous Graphene for High-Power Lithium-Sulfur Battery Applications
Structural hierarchy plays an important role in the biological world and for functional materials with optimized properties and high efficiency. As promising candidates for various energy storage systems, hierarchical porous carbon/graphene materials have been intensively investigated over the past decades, while the favorable regulation of their hierarchical porosity remains a challenge. Herein, porous CaO serves as both the catalyst and template for a versatile chemical vapor deposition (CVD) of hierarchical porous graphene. The gas atmosphere during CVD and nanostructure of adopted catalysts impact significantly on the graphitization degree and hierarchical porosity of resultant materials. The as-fabricated material exhibits abundant microsized in-plane vacancies, mesosized wrinkled pores, and macrosized strutted cavities, thereby contributing to a strong surface entrapment, short ion diffusion pathways, rapid mass transport, low interfacial resistance, and robust framework. It is demonstrated as a favorable scaffold for lithium-sulfur battery cathodes with superior rate capability, high coulombic efficiency, and excellent stability. A high capacity of 357 (656 ) is manifested at the current rate of 5.0 C, exhibiting a 74% retention of the capacity at 0.1 C. The first use of CaO-templated CVD growth of graphene reported herein opens up new perspectives on the effective fabrication of hierarchical porous graphene materials on metal oxide catalysts with promising applications in energy storage, catalysis, adsorption, drug delivery, and so on.