Synthesis of Nitrogen-Doped Porous Carbon Monolith for Binder-Free All-Carbon Supercapacitors

Hierarchical porous carbon derived from coal tar pitch by one step carbonization and activation combined with a CaO template for supercapacitors

Hierarchical porous carbon is synthesized through a one-step carbonization and activation method from coal tar pitch using CaO as the hard template.

In-situ ZnO template preparation of coal tar pitch-based porous carbon-sheet microsphere for supercapacitor

Three-dimension (3D) porous carbon-sheet microspheres (PCSMs) are prepared through coating coal tar pitch on basic zinc carbonate microspheres followed by in situ ZnO template carbonization and KOH activation. The as-prepared PCSMs show microsphere morphology composed of petal-like carbon nanosheets, which have large specific area (1359.88-2059.43 m² g^-1) and multiscale pores (mainly micropores and mesopores). As the supercapacitor electrodes, the 3D PCSMs present a good electrochemical performance with a large specific capacitance of 313 F g^-1 at 1 A g^-1 and high rate capability of 81.9% capacitance retention when increasing the current density up to 50 A g^-1 in a three-electrode system. In addition, the energy density can reach up to 18.79 Wh kg^-1 at a high power density of 878.4 W kg^-1 for PCSMs-0.2a symmetrical supercapcitor in 1 M Na₂SO₄ electrolyte.

Self-Template Synthesis of Nitrogen-Doped Hollow Carbon Nanospheres with Rational Mesoporosity for Efficient Supercapacitors

Rational design and economic fabrication are essential to develop carbonic electrode materials with optimized porosity for high-performance supercapacitors. Herein, nitrogen-doped hollow carbon nanospheres (NHCSs) derived from resorcinol and formaldehyde resin are successfully prepared via a self-template strategy. The porosity and heteroatoms in the carbon shell can be adjusted by purposefully introducing various dosages of ammonium ferric citrate (AFC). Under the optimum AFC dosage (30 mg), the as-prepared NHCS-30 possesses hierarchical architecture, high specific surface area up to 1987 m²·g^-1, an ultrahigh mesopore proportion of 98%, and moderate contents of heteroatoms, and these features endow it with a high specific capacitance of 206.5 F·g^-1 at 0.2 A·g^-1, with a good rate capability of 125 F·g^-1 at 20 A·g^-1 as well as outstanding electrochemical stability after 5000 cycles in a 6 M KOH electrolyte. Furthermore, the assembled NHCS-30 based symmetric supercapacitor delivers an energy density of 14.1 W·h·kg^-1 at a power density of 200 W·kg^-1 in a 6 M KOH electrolyte. This work provides not only an appealing model to study the effect of structural and component change on capacitance, but also general guidance to expand functionality electrode materials by the self-template method.

Facile and Scalable Fabrication of High-Performance Microsupercapacitors Based on Laser-Scribed In Situ Heteroatom-Doped Porous Graphene

This study proposes an efficient, facile, and scalable strategy to synthesize in situ heteroatom-doped porous graphene via laser direct writing on the precursor-doped polyimide (PI) film, which is fabricated for the first time through incorporating PI powder and precursors with sodium carboxymethyl cellulose (CMC) binder by a drop-casting and low-temperature drying process. The resulting microsupercapacitors (MSCs) based on the as-prepared heteroatom-doped porous graphene exhibit remarkable capacitive performance. The typical boron-doped MSC prepared on borax-doped polyimide film possesses an ultrahigh areal capacitance of 60.6 mF cm^-2 at 0.08 mA cm^-2, which is approximately 20 times larger than that of undoped MSC. Furthermore, the boron-doped MSC has impressive cycling stability (with the capacitance retention of 96.3% after 20 000 cycles), exceptional mechanical flexibility, tunable capacitance, and voltage output through arbitrary modular serial and parallel integration. Besides, the nitrogen-doped porous graphene with excellent capacitive performance is also prepared by laser direct scribing on the sulfonated melamine-doped polyimide film, demonstrating excellent scalability and generality of this strategy. Hence, one-step laser direct writing on precursor-doped polyimide films can realize in situ heteroatom doping and generation of hierarchical porous graphene electrodes simultaneously, which opens a new avenue for the facile, cost-effective, and scalable fabrication of heteroatom-doped porous graphene, thus promising for MSCs and various flexible and wearable electronics at large-scale production.

Diaminopyrene modified reduced graphene oxide as a novel electrode material for excellent performance supercapacitors

Schematic illustration of the facile synthesis process of DAPrGOs nanocomposites, Ragone plots and the superior cyclic stability of the assembled DAPrGO1//DAPrGO1 SSS.