In view of the respective advantages of electrical double layer capacitance (EDLC) and pseudocapacitance, the development of electrode materials with dual energy storage mechanisms (EDLC and pseudocapacitance) will play a significant role in maximizing the overall capacitance performance. In this paper, the core-shell fibers with dense zeolite imidazole framework (ZIF) coating were synthesized on the electrospun composite nanofiber substrate by a rapid in-situ growth strategy. After pyrolysis of ZIFs(shell)@PAN/PVP(core) fibers, heteroatom-doped porous carbon fiber materials with high specific surface area (410.55 m2 g-1) were obtained. It not only had a layered porous structure, but also fully exposed the doped active sites, which made it have the advantages of EDLC and pseudocapacitance. As expected, the prepared porous carbon materials doped with rich heteroatom, as supercapacitor electrode materials, exhibited large specific capacitances of 492.7 F g−1 at a current density of 1 A g−1 and 406.4 F g−1 at 10 A g−1. After 5000 cycles of galvanostatic charge-discharge at 10 A g−1, its capacitance retention rate was as high as 98.65%, showing excellent charge storage performance and good cycle stability. Therefore, this work presents an effective strategy for the design and preparation of supercapacitor electrode materials with dual energy storage mechanisms.

Heteroatom-doped porous carbon derived from zeolite imidazole framework/polymer core-shell fibers as an electrode material for supercapacitor

Design of carbon aerogels with variable surface morphology for electromagnetic wave absorption

Preparation and characterization of lignin nanoparticles and chitin nanofibers reinforced PVA films with UV shielding properties

Self-supported VO(PO3)2 electrode for 2.8 V symmetric aqueous supercapacitors

Use of polyacrylonitrile-based carbon nanolayer modified Co3S4 to improve the overall performance of supercapacitors

Supercapacitors are highly attractive in the large-scale energy storage field, but the “trade-off” between the gravimetric capacitance and the volume and area specific capacitance greatly affects their further development. In this work, we developed coralloid-like porous carbon sheets (CPCS) with double support structure via a bidirectional anchoring strategy, exhibiting ultra-low specific surface area (26.95 m2 g−1) and moderate packing density (0.75 g cm−3). In the meantime, the proposed dual-anchor structure model made the interior “self-doping” defects and the exterior “foreign-doping” defects fully exposed, which is seldom obtained by other artificial methods. Based on this, it delivered a superior overall performance in gravimetric, volumetric, and areal capacitances (308.89 F g−1, 231.67 F cm−3, and 1146 μF cm−2) and stable cyclability (10 000 cycles), which is the highest capacitance reported for polyacrylonitrile-based hard carbon without chemical/physical activation. Considering the low-energy and innovative synthesis route, our work may shed some light on developing advanced carbons promising for supercapacitors.

Design of unique porous carbons with double support structure: toward overall performance by employing bidirectional anchoring strategy

A small size effect could be conducive to enhancing the electrochemical performance, while the mechanism by which they also increase the capacitance for carbon electrode materials has not been established. Here, ultrasmall polyacrylonitrile particles with controllable sizes are supported on poly(ionic liquid)s microspheres (PILMs/PAN) by epitaxial polymerization growth strategy. Unlike traditional subtraction formulas in developing a porous architecture, we report on the synthesis of creating numerous micro/mesopores in carbon materials by addition theorem, and thus making for the perfection of packing density, which has not been reported yet. As an example, PILMC/PAN-L with a well-balanced specific surface area of 875.38 m2 g−1 and packing density of 1.05 g cm−3 demonstrated gravimetric and volumetric capacitances of 309 F g−1 and 324.45 F cm−3 at 0.5 A g−1, showing good rate performance and stable cyclability. Moreover, the underlying mechanism is thoroughly developed using multiple electrochemical methods. On this basis, this work would afford avenues to further enhancing the electrochemical performance, especially in exploring advanced carbon materials.

Chengyao Zhao

Papers

Design of unique porous carbons with double support structure: toward overall performance by employing bidirectional anchoring strategy

Investigation of the mechanism of small size effect in carbon-based supercapacitors.