Covalent organic framework (COF) is a new class of porous materials used in energy storage devices. By solvothermal method, the triphenylamine-based covalent organic framework was synthesized using Schiff base coupling reaction between tris(4-aminophenyl) amine (TAPA) and tris(4-formylphenyl) amine. The regular pore structure of TPA-COFs not only exposes more active sites of triphenylamine structure to electrolyte solution during the chargedischarge process, but also accelerates the transport of ions in the active layer.At the same time, the π-electron conjugated system and the interlayer π-π stacking effect effectively promote the conduct of electrons in the two-dimensional and three-dimensional directions of COFs materials, which improves the electrochemical performance of the materials. TPA-COFs show a higher specific capacitance of 263.1 F/g at 0.1 A/g. At the same time, TPA-COFs materials exhibit a high specific surface area of 398.59 m 2 /g. After 5000 cycles of charge-discharge, the capacitance retention rate of TPA-COFs is 111%, showing excellent cycle stability.
Current,
there is an urgent demand for electrode materials with
superior electrochemical performances for the development of supercapacitors.
A nitrogen-doped carbon skeleton (NCS) assembled by carbon nanotubes
and graphene layers is designed and synthesized utilizing a layer-shaped
humate-based zeolitic imidazolate framework (ZIF) (HA-CoFe-ZIF) as
a template in this work. The synthesized NCS is mainly composed of
graphitized carbon with a few hydroxyl groups on its surface, synchronously
doped by 9.5 at % nitrogen in the state of pyridinic N and pyrrolic
N. The rich mesoporous structure entitles it to a high Brunauer–Emmett–Teller
(BET) specific surface area of 427 m2 g–1 and suitable BET average pore diameter of 3.14 nm. The NCS has a
high capacity of 324 F g–1 at 1 A g–1, good rate capability (capacitance retention of 71% from 5 to 100
A g–1), and excellent cycling stability (capacitance
retention of 96 and 87% after 5000 and 10 000 cycles, respectively).
The fabricated NCS//AC asymmetric supercapacitor also exhibits a high
capacity of 93 F g–1 at 1 A g–1, large energy density of 10.3 Wh kg–1 at 331 W
kg–1, and good cycling performance (capacitance
retention of 88% after 5000 cycles). Our elaborately designed NCS
materials exhibit multiple structural advantages including rich mesoporous
structure, various graphitic carbon, and high-dosage nitrogen doping,
resulting in high capacitance performances. This humate-based metal–organic
framework (MOF)-derived strategy provides a good idea for the synthesis
of high-performance carbon skeleton materials applied to energy storage.
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