Microwave Assisted Synthesis of Porous NiCo2O4 Microspheres: Application as High Performance Asymmetric and Symmetric Supercapacitors with Large Areal Capacitance

Abstract

Large areal capacitance is essentially required to integrate the energy storage devices at the microscale electronic appliances. Energy storage devices based on metal oxides are mostly fabricated with low mass loading per unit area which demonstrated low areal capacitance. It is still a challenge to fabricate supercapacitor devices of porous metal oxides with large areal capacitance. Herein we report microwave method followed by a pyrolysis of the as-prepared precursor is used to synthesize porous nickel cobaltite microspheres. Porous NiCo2O4 microspheres are capable to deliver large areal capacitance due to their high specific surface area and small crystallite size. The facile strategy is successfully demonstrated to fabricate aqueous-based asymmetric & symmetric supercapacitor devices of porous NiCo2O4 microspheres with high mass loading of electroactive materials. The asymmetric & symmetric devices exhibit maximum areal capacitance and energy density of 380 mF cm−2 & 19.1 Wh Kg−1 and 194 mF cm−2 & 4.5 Wh Kg−1 (based on total mass loading of 6.25 & 6.0 mg) respectively at current density of 1 mA cm−2. The successful fabrication of symmetric device also indicates that NiCo2O4 can also be used as the negative electrode material for futuristic asymmetric devices.

Three dimensional iron oxide/graphene aerogel hybrids as all-solid-state flexible supercapacitor electrodes

“…For quantitative considerations, the specific capacitance was calculated as follows: In the three-electrode measurement, the specific capacitance is calculated from charge-discharge profiles using the following equation: Cs=(I×t)/(V×m) For two electrodes symmetric system the following equation is used to calculate the specific capacitance: Cs= 2×I×dt/m× ΔV [22] Where Cs (F/g) is specific capacitance of the supercapacitor, I (A) corresponds to the discharge current, ΔV (V) is the potential window, Δt(s) is the discharge time, and m (g) refers to the mass of active materials on the one electrodes. For quantitative considerations, the specific capacitance was calculated as follows: In the three-electrode measurement, the specific capacitance is calculated from charge-discharge profiles using the following equation: Cs=(I×t)/(V×m) For two electrodes symmetric system the following equation is used to calculate the specific capacitance: Cs= 2×I×dt/m× ΔV [22] Where Cs (F/g) is specific capacitance of the supercapacitor, I (A) corresponds to the discharge current, ΔV (V) is the potential window, Δt(s) is the discharge time, and m (g) refers to the mass of active materials on the one electrodes.…”

Atypical BiOCl/Bi2S3 hetero-structures exhibiting remarkable photo-catalyst response

“…However, the atypical architectures fabricated from hard template and through two-step synthetic strategies mostly suffering from their high cost and tedious synthetic procedures [19][20][21][22][23][24][25]. So it is highly desirable to develop one-pot synthesis of novel inorganic materials without templates and to explore their multifunction.…”

Microwave Synthesis of Zinc Ammonium Phosphate/Reduced Graphene Oxide Hybrid Composite for High Energy Density Supercapacitors

“…Thus, the XRD studies have confirmed the complexation of GO as rGO localized in the ZAP matrix. The conformation envelope of ZAPG2 yielded a smaller crystallite size of 32.2 nm than ZAP (69.2 nm) (Debye–Scherrer relation), paving the way for the improved electrochemical performance of ZAPG2 compared to that of the pure ZAP …”