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Electrospinning is a simple and effective technique for preparing carbon nanofibers. However, carbon nanofiber materials have some drawbacks, such as low specific surface area, small pore size, and low porosity, which can affect the electrochemical performance of supercapacitors. This article proposes a preparation method for a multi-level porous structure for thick electrodes. Sponge-like nanofibers are formed through electrospinning by adding a certain amount of PMMA to the polyacrylonitrile mixed spinning solution after doping with heteroatoms. After reverse hanging pre-oxidation and carbonization, a hierarchical porous, highly conductive, and flexible carbon nanofiber sponge is obtained. After testing, at a current density of 0.25 A g−1, its specific capacitance reached 207 F g−1. As the power density increased from 250 W kg−1 to 3997.89 W kg−1, the energy density changed from 28.73 W h kg−1 to 8.44 W h kg−1, demonstrating that the porous active carbon nanofiber sponge electrode has a significant energy storage advantage. [ABSTRACT FROM AUTHOR]

As interest in smart textiles grows, fiber-based supercapacitors are gaining attention as promising devices for powering wearable electronics. Herein, we have demonstrated a two-step manufactured hybrid fiber with excellent energy storage properties. Anhydrous MXene (Ti3C2Tx) sheets are primarily spun in synergy with liquid crystal carbon nanotubes (CNTs) to produce a continuous fiber as a promising electrode material, which solves the problem of poor rate capability owing to the sheet re-stacking of MXene. MnO2@MXene/CNT fibers are subsequently prepared by electrochemical deposition with controlled time. The optimal content of MXene (10 wt%) and a perfect thickness of the MnO2 layer (4 μm) are testified to achieve an excellent capacitance of 371.1 F cm−3 in three-electrode system, which is about 200% and 1800% higher than that of 10 wt%-MXene/CNT and CNT fiber electrode, respectively. Symmetric fiber supercapacitor is assembled by paralleling two fibers with LiCl/PVA gel electrolyte, manifesting a superior cycling stability of 86.3% after 10000 cycles. Anhydrous MXene nanosheets and CNTs are incorporated by a high yield spinning technique to prepare continuous hybrid fibers as a conductive framework for MnO2 deposition, exhibiting stable and outstanding energy storage properties in supercapacitor. [ABSTRACT FROM AUTHOR]

With the continuous demands for wearable electronics, the embeddable power sources have drawn attention to develop advanced electrode materials and feasible manufacture procedures. Fiber‐based flexible energy storage devices have the potential to be practically integrated by utilizing the high‐performance materials with precisely constructed structures. Herein, a novel approach is presented to achieve an outstanding fiber‐based supercapacitor by simultaneous wet‐spinning of mesoporous MXene (Ti3C2Tx) nanoflakes. The volumetric capacitance of the porous fiber is enhanced up to ≈145% when the content of mesoporous MXene reaches 15 wt%. The symmetric all‐solid‐state fiber supercapacitor shows an extraordinary capability of 821.5 F cm–3 at a current density of 0.5 A cm–3, which reflects an enormous improvement to that of a nonporous MXene fiber‐based supercapacitor. The measured energy density is 8.9 mWh cm–3 at a power density of 401 mW cm–3, which also indicates the effective synergy of the constructed pathways for ions and electrons. This work demonstrates the feasibility of scalable production of fiber‐based electrode materials with porous MXene for powering wearable applications. [ABSTRACT FROM AUTHOR]

Abstract: The demands for wearable technologies continue to grow and novel approaches for powering these devices are being enabled by the advent of new electromaterials and novel fabrication strategies. Herein, a novel approach is reported to develop superelastic wet‐spun hybrid carbon nanotube graphene fibers followed by electrodeposition of polyaniline to achieve a high‐performance fiber‐based supercapacitor. It is found that the specific capacitance of hybrid carbon nanotube (CNT)/graphene fiber is enhanced up to ≈39% using a graphene to CNT fiber ratio of 1:3. Fabrication of spring‐like coiled fiber coated with an elastic polymer shows an extraordinary elasticity capable of 800% strain while affording a specific capacitance of ≈138 F g−1. The elastic rubber coating enables extreme stretchability and enabling cycles with up to 500% strain for thousands of cycles with no significant change in its performance. Multiple supercapacitors can be easily assembled in series or parallel to meet specific energy and power needs. [ABSTRACT FROM AUTHOR]

The ubiquity of wearables, coupled with the increasing demand for power, presents a unique opportunity for nanostructured fiber-based mobile energy storage systems. When designing wearable electronic textiles, there is a need for mechanically flexible, low-cost and light-weight components. To meet this demand, we have developed an all-in-one fiber supercapacitor with a total thickness of less than 100 μm using a novel facile coaxial wet-spinning approach followed by a fiber wrapping step. The formed triaxial fiber nanostructure consisted of an inner poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) core coated with an ionically conducting chitosan sheath, subsequently wrapped with a carbon nanotube (CNT) fiber. The resulting supercapacitor is highly flexible, delivers a maximum energy density 5.83 Wh kg−1 and an extremely high power of 1399 W kg−1 along with remarkable cyclic stability and specific capacitance. This asymmetric all-in-one fiber supercapacitor may pave the way to a future generation of wearable energy storage devices. [ABSTRACT FROM AUTHOR]

• Numbers of –F and –OH groups of Ti 3 C 2 T x could be removed by carbonizing. • Cotton fabrics contain the inherent flexibility after carbonizing. • High load of Ti 3 C 2 T x flakes on flexible substrate. • High areal capacitance of flexible supercapacitor based on Ti 3 C 2 T x /TiO 2 heterojunction. Flexible Carbonized MXene/Cotton fabric is prepared by dipping cotton fabric into Ti 3 C 2 T x suspension and carbonizing the composite fabric. Cotton fabric, embedded by Ti 3 C 2 T x flakes without the assistance of crosslinkers and binders, is the most used precursor of all carbon sources. In this work, Ti 3 C 2 T x flakes with different concentrations ranging from 2 to 8 wt% are loaded on cotton fabric and carbonized subsequently under the temperature from 800 to 1200 °C. The highest areal capacitance dramatically reaches to 794.2 mF cm−2 (233.6 F g−1) at a scan rate of 2 mV s−1 with 6 wt% Ti 3 C 2 T x at 1000 °C, which shows a 74% improvement compared to the carbonized cotton cloth dipped into the Ti 3 C 2 T x dispersions under same condition. Also, the assembled all-solid-state flexible supercapacitor remains 74% of capacitance even after 10,000 charge and discharge cycles showing a stable rechargeable ability. From a variety of cellulosic materials, the method can be used to produce Ti 3 C 2 T x composite fabrics which are promising candidates of energy storage, electromagnetic shielding, sensing, absorbing, electrocatalysis, etc. [ABSTRACT FROM AUTHOR]