Optimized spherical manganese oxide-ferroferric oxide-tin oxide ternary composites as advanced electrode materials for supercapacitors. (18th September 2015)

• Record Type: Journal Article
• Authors: Zhu, Jian; Tang, Shaochun; Vongehr, Sascha; Xie, Hao; Meng, Xiangkang
• Is Part Of: Nanotechnology. Volume 26:Number 37(2015)
• Page Start: 4048
• Page End: 4055
• Publication Date: 2015-09-18
• Subjects: Nanotechnology -- Periodicals; Nanotechnology -- Periodicals; Nanotechnology; Publications périodiques; Nanotechnologies; Periodicals; 620.5
• DOI: 10.1088/0957-4484/26/37/374001
• Languages: English
• ISSNs: 0957-4484

Abstract

<abstract> <title>Abstract</title> <p>Inexpensive MnO<sub>2</sub> is a promising material for supercapacitors (SCs), but its application is limited by poor electrical conductivity and low specific surface area. We design and fabricate hierarchical MnO<sub>2</sub>-based ternary composite nanostructures showing superior electrochemical performance via doping with electrochemically active Fe<sub>3</sub>O<sub>4</sub> in the interior and electrically conductive SnO<sub>2</sub> nanoparticles in the surface layer. Optimization composition results in a MnO<sub>2</sub>–Fe<sub>3</sub>O<sub>4</sub>–SnO<sub>2</sub> composite electrode material with 5.9 wt.% Fe<sub>3</sub>O<sub>4</sub> and 5.3 wt.% SnO<sub>2</sub>, leading to a high specific areal capacitance of 1.12 F cm<sup>−2</sup> at a scan rate of 5 mV s<sup>−1</sup>. This is two to three times the values for MnO<sub>2</sub>-based binary nanostructures at the same scan rate. The low amount of SnO<sub>2</sub> almost doubles the capacitance of porous MnO<sub>2</sub>–Fe<sub>3</sub>O<sub>4</sub> (before SnO<sub>2</sub> addition), which is attributed to an improved conductivity and remaining porosity. In addition, the optimal ternary composite has a good rate capability and an excellent cycling performance with stable capacitance retention of ∼90% after 5000 charge/discharge cycles at 7.5 mA cm<sup>−2</sup>. All-solid-state SCs are assembled with such electrodes using polyvinyl alcohol/Na<sub>2</sub>SO<sub>4</sub> electrolyte. An integrated device made by connecting two identical SCs in series can power a light-emitting diode indicator for more than 10 min.</p> </abstract>