Porous indium oxide hollow spheres (PIOHS) for asymmetric electrochemical supercapacitor with excellent cycling stability

Porous indium oxide hollow spheres (PIOHS) of 1-2 mm in diameter were synthesized using a cost-effective hydrothermal method followed by the calcination. First, solid carbon-In2O3 composite sphere was formed using indium salt and glucose as indium and carbon precursor, respectively. Porous and hollow structure of pure indium oxide was formed after the successful removal of carbon that acted as a sacrificial template during the high-temperature calcination. Various characterization tools such as electron microscopy, Raman spectroscopy, and electrochemical techniques were used to characterize the synthesized PIOHS. From BET measurements, the specific surface area was estimated as 128 m(2) g(-1) and the electrode made of PIOHS showed maximum specific capacitance of 320 F g(-1) at 1 A g(-1) current density during electrochemical studies. This material exhibited 56% rate capability at 10 A g(-1) with 86% cycling stability after 3500 cycles at 5 A g(-1) . The full cell asymmetric supercapacitor was demonstrated with PIOHS as a cathode with a specific capacitance, energy density and power density of 30.84 F g(-1), 10.96 Wh kg(-1) and 80 W kg(-1), respectively at 0.1 A g(-1) current density along with the specific capacitance retention of 97.1% after 1000 cycles at 1 A g(-1) current density. The excellent electrochemical performance of the fabricated full-cell device is mainly attributed to the high surface area, unique three-dimensional porous hollow architecture and better charge transfer kinetics of PIOHS. (c) 2018 Elsevier Ltd. All rights reserved.