title: Freestanding three-dimensional graphene/MnO2 composite networks as ultralight and flexible supercapacitor electrodes.
abstract: A lightweight, flexible, and highly efficient energy management strategy is needed for flexible energy-storage devices to meet a rapidly growing demand. Graphene-based flexible supercapacitors are one of the most promising candidates because of their intriguing features. In this report, we describe the use of freestanding, lightweight (0.75 mg/cm(2)), ultrathin (<200 μm), highly conductive (55 S/cm), and flexible three-dimensional (3D) graphene networks, loaded with MnO(2) by electrodeposition, as the electrodes of a flexible supercapacitor. It was found that the 3D graphene networks showed an ideal supporter for active materials and permitted a large MnO(2) mass loading of 9.8 mg/cm(2) (~92.9% of the mass of the entire electrode), leading to a high area capacitance of 1.42 F/cm(2) at a scan rate of 2 mV/s. With a view to practical applications, we have further optimized the MnO(2) content with respect to the entire electrode and achieved a maximum specific capacitance of 130 F/g. In addition, we have also explored the excellent electrochemical performance of a symmetrical supercapacitor (of weight less than 10 mg and thickness ~0.8 mm) consisting of a sandwich structure of two pieces of 3D graphene/MnO(2) composite network separated by a membrane and encapsulated in polyethylene terephthalate (PET) membranes. This research might provide a method for flexible, lightweight, high-performance, low-cost, and environmentally friendly materials used in energy conversion and storage systems for the effective use of renewable energy.
authors.affiliation: School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China. heyongming11@163.com
authors.forename: Yongmin
authors.initials: Y
authors.lastname: He
authors.forename: Wanjun
authors.initials: W
authors.lastname: Chen
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jiecai
authors.initials: J
authors.lastname: Fu
authors.forename: Changhui
authors.initials: C
authors.lastname: Zhao
authors.forename: Erqing
authors.initials: E
authors.lastname: Xie
mesh_terms: D055119:Elastic Modulus; D025802:Electric Capacitance; D011211:Electric Power Supplies; D004566:Electrodes; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation*; D010087:Oxides / Q000737:chemistry*
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D006108:Graphite; C016552:manganese dioxide