Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117576 Singapore.
ACS Appl Mater Interfaces. 2012 Feb;4(2):1058-64. doi: 10.1021/am2016848. Epub 2012 Feb 6.
Hierarchical graphene-based composite consisting of graphene sheets intercalated by MnO(2)-coated carbon nanotubes (MnC) was prepared for high-performance supercapacitor electrode. The highly negatively charged graphene oxides reduced by urea (RGO) and the positively charged MnC functionalized with poly(diallyldimethylammonium chloride) created a strong electrostatic interaction, forming a hierarchical nanostructure. The elelctrocapacitive behaviors of MnC/RGO (MnC-G) were systematically investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 193 F/g was achieved for the MnC-G composite with 37% RGO, which was almost 3-fold higher than 69 F/g of carbon nanotubes/RGO and 2-fold higher than 89 F/g of MnO(2)/RGO composite. Moreover, an excellent rate performance, a good capacitance retention (~70%) and a superior Coulombic efficiency (94-96%) were also observed during the continuous 1300 cycles of galvanostatic charge-discharge.
层状石墨烯基复合材料由石墨烯片层间插层的 MnO(2)包覆碳纳米管 (MnC) 组成，用于高性能超级电容器电极。高度带负电荷的由尿素还原的氧化石墨烯（RGO）和带正电荷的用聚二烯丙基二甲基氯化铵官能化的 MnC 之间产生强烈的静电相互作用，形成了分层纳米结构。通过循环伏安法、恒电流充放电和电化学阻抗谱对 MnC/RGO（MnC-G）的电容行为进行了系统研究。在 37% RGO 的情况下，MnC-G 复合材料的比电容达到 193 F/g，几乎是碳纳米管/RGO 的 3 倍，MnO(2)/RGO 复合材料的 2 倍。此外，在连续 1300 次恒流充放电循环中还观察到优异的倍率性能、良好的电容保持率（~70%）和卓越的库仑效率（94-96%）。
