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[Display omitted] • The vacancy-defective graphene sheets are constructed successfully through polyacrylonitrile thermally mediated. • Vacancy defects on graphene sheets can enhance electrons/ions transport kinetics • The assembled aqueous zinc-ion hybrid supercapacitors exhibit a high energy density and outstanding cycling stability. The electrochemical behavior of graphene sheets in energy storage system is closely related to its electronic structures. Specifically, structural vacancy defects can expose more active sites and enhance the electrochemical performance. However, it is still a challenging problem to realize valid defect regulation on improving the reaction kinetics of electrode materials. Herein, vacancy-defective graphene sheets were constructed through the thermal mediated method via intercalation of polyacrylonitrile nanofibers. The vacancy defects were generated from the NH 3 gas resulting from polymer decomposition at gradient carbonization temperature. The obtained composites of the graphene sheets and carbon nanofibers demonstrate that the vacancy defects benefit to charge transport, allowing more electrons to pass through the interlayered structure, and enhance the adsorption capacitance during the reversible electrochemical process. In addition, the as-assembled Zn ion hybrid supercapacitors exhibit a high energy density of 129.9 Wh kg−1 and outstanding cyclic stability (99.8 % after 10,000 cycling). The confined polymer-mediated thermal modification strategy can afford abundant vacancy defective sites and exhibit promising outlook for constructing high-performance graphene-based electrode materials for Zn ion hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The NB-PCNF and MnO 2 /Co 3 O 4 /NB-PCNF were successfully fabricated via needleless electrospinning. • The co-doping of multiple non-metallic atoms enhances the electrochemical capability of carbon nanofibers. • The heterogeneous structure in MnO 2 /Co 3 O 4 /NB-PCNF can effectively improve the electrical conductivity. • A flexible asymmetric solid-state supercapacitor (FASS-SC) exhibits excellent electrochemical performance. Rational design of an electrode material with high flexibility and electrochemical performance is the key to wearable energy storage devices. Herein, a facile and productive needleless electrospinning method was introduced to prepare self-supported and flexible nanofibrous electrode materials for asymmetric capacitor. The MnO 2 nanoclusters and ZIF67-derived Co 3 O 4 nano-sheets were sequentially deposited on the surface of N, B-doped carbon nanofibers (hetero-junction MnO 2 /Co 3 O 4 /NB-PCNF). Attributing to the constructed multi-pathway for redox reactions on electrode, the specific capacitance of NB-PCNF and MnO 2 /Co 3 O 4 /NB-PCNF can reach up to 204.2F/g and 141.43F/g at a small current density of 0.1 A/g, respectively. In long-term cycling tests, the electrode materials exhibited excellent cycling stability and good rate capability. The electrodes were assembled with Potassium-ion hydrogel electrolyte to form a flexible asymmetric solid-state supercapacitor (FASS-SC). FASS-SC can reach a voltage window of 1.6 V. It provided 28.2 W h/kg at an energy density of 600 W/kg and a specific capacitance retention of 94.18 % after 10,000 cycles. The FASS-SC offers new research ideas for future flexible devices and wearable technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • ● A dual network organohydrogel based asymmetric supercapacitor exhibits temperature tolerance from −20 to 80 °C. • ● High operation voltage of 1.7 V and a high energy density of 51.1Wh kg−1 is obtained with the supercapacitor. • ● Over the repeated cycles of heating and cooling between –20 and 80 °C, 94% of the initial capacitance is retained. • ● The supercapacitor exhibits mechanical stability over bending regardless of the temperature. It is highly desirable for supercapacitors to achieve mechanical flexibility and temperature tolerance, as well as high energy density, to fully utilize their superior characteristics of high-power density and long cycle stability to realize their potential as practical wearable energy storage devices. We devise a novel strategy to fabricate a flexible asymmetric supercapacitor based on dual network organohydrogel, exhibiting high energy density and electrochemical stability over a wide temperature range spanning 100 ℃. A three-dimensional core–shell NiCo 2 O 4 @MnO 2 nanostructure is selected as the positive electrode to supply multiple ion diffusion channels through its mesoporous structure, and nano structured N-doped carbon nanofibers as the negative electrode to increase the contact area with electrolyte, and 6 M KOH based organohydrogel as electrolyte. The resulting supercapacitor exhibits high electrochemical performance including a high operation voltage of 1.7 V and high energy density of 51.1 Wh kg−1 at a power density of 850 W kg−1 and is stable over temperature changes between –20 and 80 ℃. This work demonstrates a high-performance supercapacitor designed with 3D asymmetric electrodes and a dual network organohydrogel, suitable as a practical energy storage device, requiring mechanical stability and stability against temperature change. [ABSTRACT FROM AUTHOR]

[Display omitted] • All-carbon aerogels of helical carbon nanocoils (CNCs)/reduced graphene oxide (rGO)/carbon nanofibers (CNFs) are successfully synthesized. • CNCs prevent the stacking of rGO and enlarge the spaces between rGO. Moreover, the growth of CNFs improves the specific surface area and conductivity. • Our work provides new inspiration for the design of multidimensional rGO-based aerogels for energy storage electrodes. Reduced graphene oxide (rGO)-based aerogels with multidimensional structures have shown enormous potential for electrodes in supercapacitors. Currently, the interlayer stacking of rGO largely limits their capacitance performance and leads to poor structural stability. Herein, the multidimensional all-carbon aerogel of helical carbon nanocoils (CNCs)/rGO/carbon nanofibers (CNFs) has been synthesized by hydrothermal self-assembly and in-situ chemical vapor deposition (CVD). In this ternary electrode, three-dimensional (3D) CNCs serve as the inner skeleton, which facilitates the construction of 3D porous architectures and reinforces the structural stability. The intercalated CNCs prevents the stacking of rGO and effectively enlarges the spaces between rGO. Moreover, the uniform growth of one-dimensional CNFs improves the specific surface area and electrical conductivity. Due to the synergistic effect and hierarchical assembly of these components, the CNCs/rGO/CNFs electrode not only exhibits a high areal capacitance of 1581.7 mF cm−2 at 0.5 mA cm−2 in a 6 M KOH electrolyte but also shows excellent cycling durability with 108.1% capacitance retention over 30,000 cycles. This work provides inspiration and guidance for the design of multidimensional electrode materials, which has huge application potential in future energy storage devices. [ABSTRACT FROM AUTHOR]