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The multilayer hybrids of pristine graphene and polyaniline nanofiber were prepared via layer-by-layer vacuum filtration for making a high-performance supercapacitor. The specific capacitance of the hybrids electrode in the three-electrode system was measured as high as 565 F/g at a current density of 0.1 A/g, and the as-prepared supercapacitor exhibited high energy density and power density of 19.28 Wh/kg and 3.2 kW/kg, respectively. The synergistic effect of crosslinking polyaniline nanofiber network and pristine graphene intercalation not only provided larger specific areas exposed to electrolyte and improved the penetration rate of electrolyte but also improved the electrical conductivity as well as shorten the charge transmission pathways of electrons from electrode to current collector. The results demonstrate that the supercapacitor electrodes with excellent capacitive performance can be fabricated by constructing a multilayer hybrid of graphene and polyaniline nanofiber. [ABSTRACT FROM AUTHOR]

A simple, scalable approach is developed to fabricate a flexible hybrid paper electrode composed of the polyaniline/graphene and the carbon fiber (CF)-reinforced bacterial cellulose. The prepared hybrid paper presents high areal capacitance of 4.145 F cm−2 at 5 mA cm−2 and an extremely low sheet resistance of 29.7 Ω sq.−1. The CF endows the paper electrode remarkable foldability with no mechanical destruction. Even after being repeatedly bent 180° up to 1000 times, the initial capacitance can be retained up to 98%. A fabricated all-solid-state supercapacitor based on the resulting paper electrode has an excellent areal capacitance of 630 mF cm−2 and energy density of 2.8 mWh cm−3. The results confirm that this approach can fabricate the highly foldable and shape-tailorable energy storage devices and may have wide potential applications. [ABSTRACT FROM AUTHOR]

The inlet plays a significant role in the hypersonic airbreathing propulsion. A fixed-geometry inlet is troubled by low air-capture ratio and large additional drag while operating below the design Mach number. Whereas a variable-geometry inlet can maximize performance, but adds weight and complexity to the propulsion system. Based on a fluidic shock shape control technique, this paper proposes a new concept of variable hypersonic inlet with fixed geometry, gives the realization scheme, and conducts a preliminary validation. The results show that the control of the external shock system and the effective throat area can be achieved by the self-provided high pressure fluid of the inlet. For an inlet with an operating Mach-number region of 4 to 6, the shock-on-lip condition can be maintained from Mach 5 to Mach 6 with the maximum expense of 1.8% secondary flow ratio, resulting in 20% extra captured mass flow and 8% less forebody drag at low Mach numbers compared with conventional fixed-geometry inlets. Thus, the performance enhancement by using the proposed variable inlet can substantially benefit the acceleration process of hypersonic vehicles at low Mach numbers. [ABSTRACT FROM AUTHOR]