Congratualtion, Chang Jian's paper accepted in Advanced Functional Materials.
Title: "Asymmetric Supercapacitors Based on Graphene/MnO2 Nanospheres and Graphene/MoO3 Nanosheets with High Energy Density"
Authors: Jian Chang, Meihua Jin, Fei Yao, Tae Hyung Kim, Viet Thong Le, Hongyan Yue, Fethullah Gunes, Bing Li, Arunabha Ghosh, Sishen Xie and Young Hee Lee
Abstract: Asymmetric supercapacitors with high energy density have been fabricated successfully using self-assembled reduced graphene oxide (RGO)/MnO2 (GrMnO2) composite as a positive electrode and RGO/MoO3 (GrMoO3) composite as a negative electrode in safe aqueous Na2SO4 electrolyte. The operation voltage was maximized by choosing two metal oxides with largest work function difference. Because of the synergistic effects of highly conductive graphene and highly pseudocapacitive metal oxides, the hybrid nanostructure electrodes exhibited better charge transport and cycling stability. The operation voltage was expanded to 2.0 V in spite of the use of aqueous electrolyte, revealing high energy density of 42.6 Wh kg-1 at a power density of 276 W kg-1 and a maximum specific capacitance of 307 F g-1 and consequently giving rise to excellent Ragone plot. In addition, the GrMnO2 // GrMoO3 supercapacitor exhibited improved capacitance with cycling up to 1000 cycles, which is explained by the development of micropore structures during repetition of ion transfer. Our strategy for the choice of metal oxides by optimizing work function difference provides a promising route for next generation of supercapacitors with high energy and high power density.