杂原子掺杂三维石墨烯水凝胶的制备及电化学性能

Preparation and electrochemical properties of heteroatom-doped graphene hydrogels

采用水热法分别制备了氮、磷、硫等杂原子掺杂的三维石墨烯水凝胶电极材料。利用扫描电子显微镜(SEM)、透射电镜(TEM)、拉曼光谱仪、X射线衍射仪(XRD)和光电子能谱仪(XPS)对材料的微观结构进行了分析,并利用电化学方法对材料的电化学性能进行了研究。结果表明:氮、磷、硫等杂原子掺杂入石墨烯晶格,掺杂的石墨烯呈现三维多孔层状形貌。杂原子的掺杂均有利于提高石墨烯的电化学性能,其中以磷掺杂石墨烯电极材料的性能最佳,原子半径最大的P掺杂使石墨烯晶格畸变加剧,比表面积显著增大进而保证了电解质在材料中的快速嵌入和脱出。在1 mol/L H2SO4的电解液中,电流密度为1 mA/cm^2时,其比容量388 F/g,组装成对称双电极电池装置,其能量密度在1 A/g的电流密度下可达到25.2 Wh/kg。优异的电容性能主要源于杂原子掺杂所提供的法拉第赝电容。

Graphene hydrogel electrode materials doped with nitrogen,phosphorus and sulfur were prepared by a hydrothermal method.SEM,TEM,Raman spectroscopy,XRD and XPS were used to characterize their microstructures and electrochemical properties for use as supercapacitor electrodes.The results indicate that nitrogen,phosphorus and sulfur are doped in the graphene lattice and that they improve the electrochemical performance of graphene with phosphorus being the best of them.Because of their having the largest atomic radius,P atoms produce the largest graphene lattice distortion and significantly increase the specific surface area,which is favorable for fast ion transfer.The capacitance of the P-doped graphene is 388 F/g at a current density of 1 mA/cm^2 in a 1 mol/L H2SO4 electrolyte.A symmetrical cell using the P-doped graphene as the electrodes delivers an energy density of 25.2 Wh/kg at a current density of 1 A/g.The high capacitance of the doped graphene is mainly due to the Faraday pseudocapacitance provided by the heteroatoms.