Publications by authors named "Fengyao Chi"

Capturing and separating carbon dioxide, particularly using porous carbon adsorption separation technology, has received considerable research attention due to its advantages such as low cost and ease of regeneration. In this study, we successfully developed a one-step carbonization activation method using freeze-thaw pre-mix treatment to prepare high-nitrogen-content microporous nitrogen-doped carbon materials. These materials hold promise for capturing and separating CO from complex gas mixtures, such as biogas.

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Electrochemical capacitors are expected to replace conventional electrolytic capacitors in line filtering for integrated circuits and portable electronics. However, practical implementation of electrochemical capacitors into line-filtering circuits has not yet been achieved owing to the difficulty in synergistic accomplishment of fast responses, high specific capacitance, miniaturization and circuit-compatible integration. Here we propose an electric-field enhancement strategy to promote frequency characteristics and capacitance simultaneously.

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Filtering capacitors with wide operating voltage range are essential for smoothing ripples in line-powered system, which are still unsatisfactory due to low energy density and limited working voltage scopes. Herein, we report an aqueous hybrid electrochemical capacitor with areal specific energy density of 1.29 mF V cm at 120 Hz, greater than common aqueous ones.

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The booming portable electronics market has raised huge demands for the development of supercapacitors with mechanical flexibility and high power density in the finite area; however, this is still unsatisfied by the currently thickness-confined sandwich design or the in-plane interdigital configuration with limited mechanical features. Here, a spatial-interleaving supercapacitor (SI-SC) is first designed and constructed, in which the graphene microelectrodes are reversely stacked layer by layer within a three-dimensional (3D) space. Because each microelectrode matches well with four counter microelectrodes and all 3D spatial-interleaving microelectrodes have narrow interspaces that maintain the efficient ions transport in the whole device, this SI-SC has a prominent liner capacitance increase along with the device thickness.

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The filtering capacitor plays an essential role in the ever-increasing electronics for current stability in complicated environments. However, because of the low specific capacitance and bulky volume, current filtering devices have difficulty satisfying the harsh temperature environment and small size for supercomputers, electric vehicles, aircraft and so on. Therefore, an ultra-fast electrochemical capacitor is developed on the basis of vertically oriented graphene iongel electrodes (GI-EC), which demonstrates excellent alternate current line-filtering performance with both hot tolerance of up to 150 °C and a wide voltage window of 4 V.

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Capacitive energy storage has advantages of high power density, long lifespan, and good safety, but is restricted by low energy density. Inspired by the charge storage mechanism of batteries, a spatial charge density (SCD) maximization strategy is developed to compensate this shortage by densely and neatly packing ionic charges in capacitive materials. A record high SCD (ca.

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Article Synopsis
  • Sodium-ion capacitors (SICs) offer advantages like high energy density, high power density, low cost, and long lifespan, but are limited by the availability of effective capacitive cathodes.
  • Researchers developed a compact, highly ordered graphene solid (HOGS) that serves as a capacitive cathode, achieving impressive performance metrics such as a volumetric capacity of 303 F/cm and excellent stability over 10,000 cycles.
  • The innovative design of HOGS can be adapted for other metal-ion-based energy storage systems, indicating broad applicability in the future of electrochemical energy storage.
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Filtering capacitor is a necessary component in the modern electronic circuit. Traditional filtering capacitor is often limited by its bulky and rigid configuration and narrow workable scope of applications. Here, an aqueous hybrid electrochemical capacitor is developed for alternating current line filtering with an applicable wide frequency range from 1 to 10,000 Hz.

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We report a simple method that can dissolve graphene oxide (GO) in pure organic solvents (e.g., propylene carbonate) as readily as in pure water to form stable dispersions of single layer GO sheets.

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