Ultra-rapid chemical synthesis of mesoporous Bi2O3 micro-sponge-balls for supercapattery applications

Abstract Polycrystalline and mesoporous bismuth oxide (Bi 2 O 3 ) micro-sponge-balls of 4–7 μm in diameter comprising of 58–65 (±2) nm upright standing petals, separated by 100–700 (±50) nm crevices, are synthesized directly onto 3D Ni-foam at room-temperature (27 °C) using Tritonx-100 surfactant-mediated soft wet chemical method. After knowing the phase purity, surface area, pore-size distribution, micro-sponge-ball-type surface morphology, elemental analysis and binding energy confirmations of Bi 2 O 3 , a material with quasi-faradaic redox reactions responsible for supercapattery type behavior, are measured and explored. At a low scan rate, the specific capacitance of Bi 2 O 3 sponge-ball electrode, measured from 0.4 to 1.80 A g −1 current density, decreases from 559 to 211 F g −1 which is equivalent to a capacity from 155 to 58 mAh.g −1 . An asymmetric supercapacitor (ASC) device assembly of Bi 2 O 3 sponge-ball electrode with graphite i.e. Bi 2 O 3 //graphite demonstrates excellent electrochemical properties with 8 Wh kg −1 energy density at 2040 W kg −1 power density, and about 80% cycling retention over 5000 redox cycle operations. A demonstration of LED with full-bright intensity during discharge process of the Bi 2 O 3 //graphite ASC device suggests its practical potentiality and industrial viability.