Wet-spinning assembly and in situ electrodeposition of carbon nanotube-based composite fibers for high energy density wire-shaped asymmetric supercapacitor

Hierarchical Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate)/Reduced graphene oxide/Polypyrrole hybrid electrode with excellent rate capability and cycling stability for fiber-shaped supercapacitor

Fiber-shaped supercapacitor (FSSC) is considered as a promising energy storage device for wearable electronics due to its high power density and outstanding safety. However, it is still a great challenge to simultaneously achieve high specific capacitance especially at rapid charging/discharging rate and long-term cycling stability of fiber electrode in FSSC for practical application. Here, a ternary poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/reduced graphene oxide/polypyrrole (PEDOT:PSS/rGO/PPy) fiber electrode was constructed by in situ chemical polymerization of pyrrole on hydrothermally-assembled and acid-treated PEDOT:PSS/rGO (PG) hybrid hydrogel fiber. In this case, the porous PG hybrid fiber framework possesses combined advantages of highly-conductive PEDOT and flexible two-dimensional (2D) small-sized rGO sheets, which provides large surface area for the deposition of high-pseudocapacitance PPy, multiscale electrons/ions transport channels for the efficient utilization of active sites, and buffering layers to accommodate the structure change during electrochemical process. Attributed to the synergy, as-obtained ternary fiber electrode presents ultrahigh volumetric/areal specific capacitance (389 F cm^-3 at 1 A cm^-3 or 983 mF cm^-2 at 2.5 mA cm^-2) and outstanding rate performance (56 %, 1-20 A cm^-3). In addition, 80 % preservation of initial capacitance after 8000 cycles for the corresponding FSSC also illustrates its greatly improved cycle stability compared with 64 % of binary PEDOT:PSS/PPy based counterpart. Accordingly, here proposed strategy promises a new opportunity to develop high-activity and durable electrode materials with potential applications in supercapacitor and beyond.

In-situ generated NiCo2O4/CoP polyhedron with rich oxygen vacancies interpenetrating by P-doped carbon nanotubes for high performance supercapacitors

Supercapacitor with high storage capacity and small volumes are the development trends of miniaturization and portable energy storage systems. Herein, we design a novel self-supporting P-doped carbon nanotube (P-CNT) intercalating NiCo₂O₄/CoP core-shell polyhedron film. P-CNT is an ideal substrate with high electrical conductivity and interconnected porous architecture, which can enable the electrons transport to an external circuit from the electroactive component. NiCo₂O₄/CoP core-shell fluffy polyhedrons are derived from metal-organic frameworks with rich oxygen vacancies and abundant characteristics of pseudocapacitance, as well as better wettability. The self-supporting composite film readily achieves an ultra-high gravimetric and volumetric capacitance of 1918.4 F g^-1 and 1074.3 F cm^-3 at 1 A g^-1. Accordingly, as-assembled hybrid supercapacitors using two binder-free electrodes, i.e., a self-supporting composite film as the positive electrode and P-doped CNT integrating graphene film as the negative electrode, harvest a remarkable gravimetric/volumetric energy density of 68.6 W h kg^-1 (41.8 W h L^-1) at 800 W kg^-1 (488 W L^-1). Our work suggests that the rational-designed NiCo₂O₄/CoP@P-CNTs electrode is a competitive candidate for designing next-generation supercapacitors with high volumetric energy density.

Nest-Like MnO2 Nanowire/Hierarchical Porous Carbon Composite for High-Performance Supercapacitor from Oily Sludge

In the aim to go beyond the performance tradeoffs of classic electric double-layer capacitance and pseudo-capacitance, composites made out of carbon and pseudo-capacitive materials have been a hot-spot strategy. In this paper, a nest-like MnO2 nanowire/hierarchical porous carbon (HPC) composite (MPC) was successfully fabricated by a controllable in situ chemical co-precipitation method from oily sludge waste. Due to the advantages of high surface area and fast charge transfer for HPC as well as the large pseudo-capacitance for MnO2 nanowires, the as-prepared MPC has good capacitance performance with a specific capacitance of 437.9 F g-1 at 0.5 A g-1, favorable rate capability of 79.2% retention at 20 A g-1, and long-term cycle stability of 78.5% retention after 5000 cycles at 5 A g-1. Meanwhile, an asymmetric supercapacitor (ASC) was assembled using MPC as the cathode while HPC was the anode, which exhibits a superior energy density of 58.67 W h kg-1 at the corresponding power density of 498.8 W kg-1. These extraordinary electrochemical properties highlight the prospect of our waste-derived composites electrode material to replace conventional electrode materials for a high-performance supercapacitor.

Carbon Nanomaterials Embedded in Conductive Polymers: A State of the Art

Carbon nanomaterials are at the forefront of the newest technologies of the third millennium, and together with conductive polymers, represent a vast area of indispensable knowledge for developing the devices of tomorrow. This review focusses on the most recent advances in the field of conductive nanotechnology, which combines the properties of carbon nanomaterials with conjugated polymers. Hybrid materials resulting from the embedding of carbon nanotubes, carbon dots and graphene derivatives are taken into consideration and fully explored, with discussion of the most recent literature. An introduction into the three most widely used conductive polymers and a final section about the most recent biological results obtained using carbon nanotube hybrids will complete this overview of these innovative and beyond belief materials.