Fibrous Supercapacitors Research Articles

Antifreezing and stretchable all-gel-state supercapacitor with enhanced capacitances established by graphene/PEDOT-polyvinyl alcohol hydrogel fibers with dual networks

Although aqueous fibrous supercapacitor is one of the most advantageous energy storage devices for powering wearable electronics due to its excellent flexibility, outstanding cycling stability and high safety, it is still a challenge for its electroactive components to be cold-tolerant and stretchable for adapting fluctuating climate environments. Herein, a graphene/PEDOT:PSS hydrogel fiber with a continuous rose flower-like network is firstly constructed, and an antifreezing polyvinyl alcohol (PVA) network is subsequently taken into the hydrogel fiber via solvent replacement to generate an antifreezing and stretchable graphene/PEDOT-PVA hydrogel fiber with dual networks. Benefiting from superior interface compatibility of the hydrogel fiber with a PVA electrolyte, the assembled all-gel-state supercapacitor delivers a high capacitance of 281.2 F g−1 (0.1 A g−1) at 25 °C, more than twice higher than that of an aerogel fiber-based supercapacitor. Furthermore, this supercapacitor exhibits stable subzero-temperature electrochemical performances due to the smooth ion-transport channels and good conductivity of the antifreezing hydrogel fiber electrode, evidenced by the high specific capacitance of 212.6 F g−1 and the excellent capacitance retention of 91% after 5000 charge/discharge cycles at −20 °C. Finally, a highly stretchable spring-like supercapacitor exhibits an excellent capacitance retention of 92% after 5000 stretching cycles at a strain of 500%.

Highly Stretchable and Conductive Hybrid Fibers for High-performance Fibrous Electrodes and All-solid-state Supercapacitors

The development of lightweight, flexible, and stretchable energy storage systems is essential for state-of-the-art electronic devices. We propose a new and broad strategy to fabricate a stretchable and conductive GO/CNTs-TPU fiber electrode by direct wet spinning, from which a flexible fibrous supercapacitor is fabricated. The fibrous electrode exhibits a high strength of 11.68 MPa, high conductivity of 342 S/cm, and high specific capacitances (21.8 mF/cm, 36.45 F/cm3, and 95 F/g). The specific capacitance of the assembled all-solid-state hybrid fiber-shaped supercapacitor reaches 14.3 F/cm3. After 5000 charge-discharge cycles, 97% of the capacitance of the hybrid supercapacitor is maintained. These high-strength electrochemical electrode materials could be potential candidates for applications in practical and large-scale energy storage systems and textile clothes.

Biomass-derived three-dimensional carbon framework for a flexible fibrous supercapacitor and its application as a wearable smart textile.

High electrochemical performance and mechanical reliability are two important properties of the flexible fibrous supercapacitors (FFSCs) used in portable and wearable electronics. Herein, we introduce high-performance and stable FFSCs produced using Tetrapanax papyrifer with a honeycomb-like structure (the key material) acting as a frame for an activated carbon (AC) coating. The honeycomb-like structure facilitates penetration of electrolytes and electron transport in the AC particles. This reduces the contact resistance between the AC and current collector, thereby enhancing the electrochemical energy storage. The FFSCs possess long length and area specific capacitances of 20.8 mF cm−1 and 83.9 mF cm−2, respectively. In addition, the fabricated FFSCs display a maximum length (area) energy density of 3.98 μW h cm−1 (16.1 μW h cm−2) at a power density of 0.07 mW cm−1 (1.99 mW cm−2) and attain an excellent capacitance retention of 91% over 10 000 cycles. Moreover, the supercapacitors exhibit excellent mechanical flexibility with minor increase in capacitance upon bending. Three flexible fibrous supercapacitors in series power a red light-emitting diode, demonstrating the potential application of the flexible fibrous supercapacitors in smart textiles.

Hierarchical core-shell fibers of graphene fiber/radially-aligned molybdenum disulfide nanosheet arrays for highly efficient energy storage

Flexible fiber-shaped supercapacitors have broad application prospects in wearable and portable electronics and smart textiles, however, often suffered from their relatively low capacitance and energy density. In this paper, a unique core-shell fiber composed of graphene fiber and radially-aligned molybdenum disulfide nanosheet arrays (GF/MoS2) has been rationally designed and prepared. The morphology and structure of well-designed core-shell fibers were studied by Raman, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopic (EDX) elemental mapping. All-solid-state, fiber-shaped symmetric supercapacitors were constructed by packaging two parallel GF/MoS2 core-shell fibers with PVA/H2SO4 electrolyte. Owing to the synergistic effects between graphene and MoS2, the fiber-shaped supercapacitor exhibits an enhanced areal capacitance up to 189.73 mF cm−2 and a high energy density of 14.665 μW h cm−2. The fibrous supercapacitors also exhibit good stability and flexibility. This work provides a strategy to design core-shell fibrous electrodes for high performance fiber-shaped supercapacitors, which also holds great potential for future flexible electronic devices.

Construction of Metal–Organic Framework/Conductive Polymer Hybrid for All-Solid-State Fabric Supercapacitor

Metal-organic frameworks (MOFs) hold promising potential in energy storage but are limited by poor conductivity. In this work, a metal-organic framework/polypyrrole hybrid is constructed by a facile one-pot electrodeposition method in the presence of dopamine. An all-solid-state fabric supercapacitor based on this hybrid demonstrates excellent electrochemical energy-storage performance, which achieves a specific capacitance of 10 mF cm-1 (206 mF cm-2), a power density of 132 μW cm-1 (2102 μW cm-2), and an energy density of 0.8 μWh cm-1 (12.8 μWh cm-2). The stable cycling life and excellent mechanical flexibility over a wide range of working temperature are also achieved, which maintains a capacitance retention of 89% over 10 000 charging/discharging cycles, a capacitance decrease of only 4% after 1000 frizzy (360° bending) cycles, and no obvious capacitance loss under 100 repeated heating (100 °C)/cooling (-15 °C) cycles. This fibrous supercapacitor displays promising potential in wearable textile electronics as it can be easily woven into common cotton cloth. Our strategy may shed some valuable light on the construction of MOF-based hybrids for flexible energy-storage electronics.

Stretchable All-Gel-State Fiber-Shaped Supercapacitors Enabled by Macromolecularly Interconnected 3D Graphene/Nanostructured Conductive Polymer Hydrogels.

Nanostructured conductive polymer hydrogels (CPHs) have been extensively applied in energy storage owing to their advantageous features, such as excellent electrochemical activity and relatively high electrical conductivity, yet the fabrication of self-standing and flexible electrode-based CPHs is still hampered by their limited mechanical properties. Herein, macromolecularly interconnected 3D graphene/nanostructured CPH is synthesized via self-assembly of CPHs and graphene oxide macrostructures. The 3D hybrid hydrogel shows uniform interconnectivity and enhanced mechanical properties due to the strong macromolecular interaction between the CPHs and graphene, thus greatly reducing aggregation in the fiber-shaping process. A proof-of-concept all-gel-state fibrous supercapacitor based on the 3D polyaniline/graphene hydrogel is fabricated to demonstrate the outstanding flexibility and mouldability, as well as superior electrochemical properties enabled by this 3D hybrid hydrogel design. The proposed device can achieve a large strain (up to ≈40%), and deliver a remarkable volumetric energy density of 8.80 mWh cm-3 (at power density of 30.77 mW cm-3 ), outperforming many fiber-shaped supercapacitors reported previously. The all-hydrogel design opens up opportunities in the fabrication of next-generation wearable and portable electronics.

Solid‐State Hybrid Fibrous Supercapacitors Produced by Dead‐End Tube Membrane Ultrafiltration

The development of flexible supercapacitors with high volumetric performance is critically important for portable electronics applications, which are severely volume limited. Here, dead‐end tube membrane (DETM) ultrafiltration is used to produce densely compacted carbon‐nanotube/graphene fibrous films as solid‐state supercapacitor electrodes. DETM is widely used in the water purification industry, but to date its use has not been explored for making supercapacitor electrode materials. Compared with vacuum‐assisted filtration, dead‐end filtration of the mixture through a porous membrane is carried out under much higher pressure, and thus the solvent can be gotten rid of much faster, with less energy consumption and in an environmentally friendly manner. More importantly, phase separation of the solid constituents in the mixture, due to concentration increase, can be suppressed in DETM. Therefore, highly uniform and densely compacted supercapacitor electrodes can be obtained with very high volumetric energy and power density. The volumetric energy density in this work (≈2.7 mWh cm‐3) is at a higher level than all the all‐solid‐state fibrous supercapacitors reported to date. This can be attributed to the DETM process used, which produces a densely compacted network structure without compromising the availability of electrochemically active surface area.

MoS2‐Based All‐Purpose Fibrous Electrode and Self‐Powering Energy Fiber for Efficient Energy Harvesting and Storage

Here an all‐purpose fibrous electrode based on MoS2 is demonstrated, which can be employed for versatile energy harvesting and storage applications. In this coaxial electrode, ultrathin MoS2 nanofilms are grown on TiO2 nanoparticles coated carbon fiber. The high electrochemical activity of MoS2 and good conductivity of carbon fiber synergistically lead to the remarkable performances of this novel composite electrode in fibrous dye‐sensitized solar cells (showing a record‐breaking conversion efficiency of 9.5%) and high‐capacity fibrous supercapacitors. Furthermore, a self‐powering energy fiber is fabricated by combining a fibrous dye‐sensitized solar cell and a fibrous supercapacitor into a single device, showing very fast charging capability (charging in 7 s under AM1.5G solar illumination) and an overall photochemical‐electricity energy conversion efficiency as high as 1.8%. In addition, this wire‐shaped electrode can also be used for fibrous Li‐ion batteries and electrocatalytic hydrogen evolution reactions. These applications indicate that the MoS2‐based all‐purpose fibrous electrode has great potential for the construction of high‐performance flexible and wearable energy devices.

Continuous carbon nanofiber bundles with tunable pore structures and functions for weavable fibrous supercapacitors

Fiber supercapacitors weavable into smart textiles have attracted great attention. The key to fabricating such energy storage devices is to develop flexible fiber-like electrodes with tunable functionalities and low production cost. Here, we present an efficient strategy for the roll-to-roll mass production of carbonaceous nanofiber yarns with tunable pore structures and functions. Our protocol combines a modified electrospinning technique with a pyrolysis procedure, thereby using economic polymers as precursors. The as obtained fiber supercapacitors exhibit a remarkably high length-specific capacitance and excellent rate capability, demonstrating their great potential as smart textiles with energy storage functions.

Ultra-flexible fibrous supercapacitors with carbon nanotube/polypyrrole brush-like electrodes

Ultra-flexible supercapacitors with brush-like electrodes consisting of carbon nanotube/polypyrrole nanocomposites exhibit a gravimetric capacitance of 305 F g−1.

Aligned carbon nanotube/molybdenum disulfide hybrids for effective fibrous supercapacitors and lithium ion batteries

An aligned carbon nanotube/MoS2 nanosheet hybrid fiber with remarkable electrochemical properties is synthesized. It is used to fabricate flexible fibrous supercapacitors and lithium ion batteries with high specific capacitances and high specific capacities, respectively.