The
electric double-layer capacitance (EDLC)-based capacitor is
hindered with low capacitance and low energy density. Here, in this
report, we focused on the fabrication of a symmetric device having
graphene as an EDLC electrode material and redox additive KI-integrated
aqueous MgSO4 as an electrolyte. The high surface area
of graphene was produced by annealing of graphene oxide in an inert
atmosphere and confirmed through X-ray photoelectron spectroscopy
and Raman spectroscopy. The strategic 6% KI into MgSO4 delivered
the highest specific capacitance with a wide working window of 0.7
V. Electrochemical measurements showed that graphene delivered a significantly
greater specific capacitance (727.6 F/g) in a KI-integrated electrolyte
(MgSO4 + KI) compared to 89.2 F/g in a MgSO4 electrolyte, owing to species such as IO3
− and I3−(oxidation states of I). The symmetric
device showed the maximum energy density (ED) of 69.3 Wh/kg, which
can be achieved at the power density of 2.5 kW/kg, better than reported
values in monovalent-based electrolyte devices. In this report, the
charge storage mechanism, interactive association between Mg2+ ion insertion/extraction, and integration of redox KI had been comprehensively
studied. The strategy shows a new path in the design of excellent
ED capacitors without compromising the supercapacitor properties.
Manufacturing of aspheric profile of lens at nanometric level is difficult but the measurement and evaluation of metrology parameters is still a bigger challenge. For successful results of the lens systems, precise and defect free lenses are required. The manufacturing conditions have direct effect on the metrological parameters. For appropriate evaluation of metrology parameters, proper interpretation of aspheric surface parameters must be known. . In this study, the mechanical parameters, such as radius of curvature, slope error, tilt, centre thickness, and sag value of lens, were measured by using contact type form talysurf, non-contact type fizeau interferometers, and other instruments. The experimental results reveal that an increase in the spherical aberration is caused by increasing the lens thickness beyond 4.995mm or by increasing the radius of curvature beyond −13.8396mm or by increasing the aspheric higher order coefficients. Also its dependencies on the diameter of least confusion is studied.
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