A Continuous Carbon Nitride Polyhedron Assembly for High‐Performance Flexible Supercapacitors

Abstract

Flexible supercapacitors with high power density, flexibility, and durability have shown enormous potential for smart electronics. Here, a continuous graphitic carbon nitride polyhedron assembly for flexible supercapacitor that is prepared by pyrolysis of carbon nanotubes wired zeolitic imidazolate framework‐8 (ZIF‐8) composites under nitrogen is reported. It exhibits a high specific capacitance of 426 F g−1 at current density of 1 A g−1 in 1 m H2SO4 and excellent stability over 10 000 cycles. The remarkable performance results from the continuous hierarchical structure with average pore size of 2.5 nm, high nitrogen‐doping level (17.82%), and large specific surface area (920 m2 g−1). Furthermore, a flexible supercapacitor is developed by constructing the assembly with interpenetrating polymer network electrolyte. Stemming from the synergistic effect of high‐performance electrode and highly ion‐conductive electrolyte, superior energy density of 59.40 Wh kg−1 at 1 A g−1 is achieved. The device maintains a stable energy supply under cyclic deformations, showing wide application in flexible and even wearable conditions. The work paves a new way for designing pliable electrode with excellent electronic and mechanic property for long‐lived flexible energy storage devices.

Vertically Aligned Heteroatom Doped Carbon Nanosheets from Unzipped Self-Doped Carbon Tubes for High Performance Supercapacitor

“…The high-resolution N 1s peak in Figure c could be deconvoluted into three peaks: the peak at 398.8 eV is attributed to pyridine-like structure (N-6) that the N atoms are doped at the edge site of carbon plane, ,, the weak peak located at 400.3 eV is attributed to the nitrogen atoms in pyrrolic moieties (N-5), and the peak centered at 401.4 eV is associated with N atoms doped at the center of carbon planes (N-Q). ,− Among these types, the N-6 and N-5 species are the dominant N-containing functional groups in the sample. Moreover, the amount of pyridinic N (39.0%) is much higher than that of pyrrolic N (21.8%), which is agreement with reported in the literature that the pyridinic N is more stable than pyrrolic N at high temperature. , The presence of the pyridinic N and pyrrolic N in the sample will not only can improve the wettability of VACNs in electrolytes and thus increase electrolyte accessible surface area but also can enhance the capacitance performance of the electrode due to their pseudocapacitive effect. , In addition, because of the higher electronegativity (3.5) and smaller atomic diameter (70 pm) of nitrogen than carbon (3.0, 77 pm), the graphitic N will enhance the conductivity of VACNs and thus facilitate electron transfer. ,− All of the doped atoms may contribute to an enhancement of the interfacial capacitance by redox reaction. ,, In the O 1s spectrum (Figure d), three peaks located at 531.4, 532.5, and 533.5 eV represent the carbonyl groups (CO), phenol-type groups (COH)/ether-type groups (COC) and chemicsorbed O and/or adsorbed water, respectively, which can enhance the wettability and contribute to pseudocapacitance. , The XPS analysis further supports the results of XRD, Raman spectra, and TEM.…”

“…Furthermore, the mesopores in the nanosheets also provide fast transportation channels for electrolyte ions. More importantly, the N and O atoms in the N, O codoped VACNs can improve the wettability of VACNs in electrolytes and thus promote the electrolyte transfer efficiency at the solid–liquid interface. , In addition, the electronic-rich N-Q can enhance the conductivity of VACNs by modifying the band gap and thus facilitate electron transfer. ,− Additionally, the presence of the pyrridinic N, pyrrolic N, and O also can enhance the capacitance performance for their great pseudocapacitive effect, which well agrees with previous proposed redox mechanisms. ,, Except that the introduced heteroatoms may passivate the electrode surface, thereby enhancing the activation overpotential of water electrolysis . Thus, the electrode potential is expanded.…”

Flexible Solid‐State Supercapacitor Based on Carbon Nanotube/Fe 3 O 4 /Reduced Graphene Oxide Binary Films

“…The flexible supercapacitor exhibits an energy density of 36.7 Wh kg −1 at a power density of 480 W kg −1 for a 1 V window voltage, and retains 67% of its energy density as the power density increases to 5223 W kg −1 . These values are superior to the similar previously reported systems Fe 3 O 4 /carbon nanosheets (18.3 Wh kg −1 ), Polyaniline‐Based Supramolecular Hydrogels (PPH) (13.6 Wh kg −1 ), Carbon Nitride Polyhedron (25.3 Wh kg −1 ), PANI/CNT (7.1 Wh kg −1 ), Graphene/MnO 2 (6.8 Wh kg −1 ), and ethyleneevinyl acetate copolymer (EVA)/CNTs (9.4 Wh kg −1 ) …”

A “Nanopore Lithography” Strategy for Synthesizing Hierarchically Micro/Mesoporous Carbons from ZIF-8/Graphene Oxide Hybrids for Electrochemical Energy Storage

“…The BET surface areas of the activated hybrids were around 1200–1300 m 2 g –1 except for the material activated at 600 °C (383 m 2 g –1 ), which exhibited a rather limited porosity development (see Table for their textural parameters). These BET values were lower than those obtained for the activated materials prepared from ZIF-8 alone (e.g., 4234 m 2 g –1 for ZIF-8 activated at 800 °C; Table ) but were nonetheless comparable to (or even larger than) those of previously reported ZIF-8-derived porous carbons with hierarchical micro/mesoporosity generated by different strategies. − Concerning the PSDs (Figure c), whereas the activated materials derived from ZIF-8 alone were dominated by supermicropores, the most salient feature of the activated hybrids was the presence of very uniform mesoporosity with sizes between 3 and 4 nm. Significantly, the pore volume associated with such mesopores increased dramatically, both in absolute and relative terms (i.e., relative to the total pore volume), with activation temperature up to 900 °C and then started to decrease at 1000 °C (Table ).…”