Fiber Supercapacitors Research Articles

An Energy-Adjustable, Deformable, and Packable Wireless Charging Fiber Supercapacitor.

Wireless charging energy storage devices eliminate bulky wires of wearable electronics. However, rigid shape and specific charging energy restrict their applications in space-limited portable electronics. Herein, an all-carbon fiber supercapacitor is presented that features shape-adjustable, packable, and energy-controllable wireless charging functions. With the unique on-dimensional circuit structure, the maximum energy transfer efficiency from the electrical energy received by the wireless charging unit to the output energy of the fiber supercapacitor can reach up to ≈60.8%, and meanwhile this integrated fiber device exhibits an outstanding area capacity of 803 mF cm-2 and energy density of 1004 µWh cm-2, superior to most of the fiber supercapacitors. Moreover, this unique device can endure significant deformation in shape of circles ranging from 2 to 20cm diameter, and can be packed into narrow spaces, such as smart bracelet and disk-shaped pet global positioning system (GPS). By altering the device shape, the wireless charging current, voltage, and power can be adjusted in the range of 0.5-20mA, 1.4-15.5V, and 0.003-313mW, accommodating the energy requirements for nearly all existing micro-electronics. This work offers unprecedented opportunities for packable, space-confined and energy harvesting controllable wearable electronics.

Kinetic investigation of the energy storage process in graphene fiber supercapacitors: Unraveling mechanisms, fabrications, property manipulation, and wearable applications

AbstractGraphene fiber supercapacitors (GFSCs) have garnered significant attention due to their exceptional features, including high power density, rapid charge/discharge rates, prolonged cycling durability, and versatile weaving capabilities. Nevertheless, inherent challenges in graphene fibers (GFs), particularly the restricted ion‐accessible specific surface area (SSA) and sluggish ion transport kinetics, hinder the achievement of optimal capacitance and rate performance. Despite existing reviews on GFSCs, a notable gap exists in thoroughly exploring the kinetics governing the energy storage process in GFSCs. This review aims to address this gap by thoroughly analyzing the energy storage mechanism, fabrication methodologies, property manipulation, and wearable applications of GFSCs. Through theoretical analysis of the energy storage process, specific parameters in advanced GF fabrication methodologies are carefully summarized, which can be used to modulate nano/micro‐structures, thereby enhancing energy storage kinetics. In particular, enhanced ion storage is realized by creating more ion‐accessible SSA and introducing extra‐capacitive components, while accelerated ion transport is achieved by shortening the transport channel length and improving the accessibility of electrolyte ions. Building on the established structure–property relationship, several critical strategies for constructing optimal surface and structure profiles of GF electrodes are summarized. Capitalizing on the exceptional flexibility and wearability of GFSCs, the review further underscores their potential as foundational elements for constructing multifunctional e‐textiles using conventional textile technologies. In conclusion, this review provides insights into current challenges and suggests potential research directions for GFSCs.

Wet spinning for high-performance fiber supercapacitor based on Fe-doped MnO2 and graphene

As a typical material for 1D flexible supercapacitors, the inherent low conductivity and under-utilized theoretical capacity of MnO2 hinder its further development in wearable energy textiles. Herein, the Fe-doped MnO2 nanowires (Mn/Fe-5%) with superior crystal structure and linearity were synthesized by one-step hydrothermal method. Benefiting from the crystal defects and oxygen vacancies induced by Fe doping, the Fe-doped MnO2 nanowires (Mn/Fe-5%) exhibited excellent electrical conductivity and specific capacitance. Moreover, by incorporating appropriate Fe3+ to balance the surplus protonation, the tunnel structures of MnO2 become more stable. On this basis, Fe-doped MnO2/rGO hybrid fiber electrodes were constructed by wet spinning and chemical reduction strategy for the first time. Notably, the Fe-doped MnO2 nanowires were blended up to 50 %, which can be attributed to the linear morphology and intercalation action of Fe-doped MnO2 nanowires. Finally, the symmetrical fiber supercapacitors were assembled with Fe-doped MnO2/rGO hybrid fiber as electrodes. Astonishingly, the fiber supercapacitors presented significant volume-specific capacitance of 203.7 F cm−3 at 1.75 A cm−3 (1.57 times that of the MnO2/rGO fiber supercapacitors and 2.4 times that of rGO fiber supercapacitors) and impressive energy density of 28.29 mWh cm−3. Besides, the assembled solid-state fiber supercapacitors distinguished excellent deformation stability and electrochemical output stability. This work points the way to the doping modification of nanomaterials, the convenient and fast construction of hybrid fiber electrodes, the further developments of fiber supercapacitors.

High-Energy–Density Fiber Supercapacitors Based on Transition Metal Oxide Nanoribbon Yarns for Comprehensive Wearable Electronics

AbstractFiber supercapacitors (FSs) based on transition metal oxides (TMOs) have garnered considerable attention as energy storage solutions for wearable electronics owing to their exceptional characteristics, including superior comfortability and low weights. These materials are known to exhibit high energy densities, high specific capacitances, and fast redox reactions. However, current fabrication methods for these structures primarily rely on chemical deposition, often resulting in undesirable material structures and necessitating the use of additives, which can degrade the electrochemical performance of such structures. Herein, physically deposited TMO nanoribbon yarns generated via delamination engineering of nanopatterned TMO/metal/TMO trilayer arrays are proposed as potential high-performance FSs. To prepare these arrays, the target materials were initially deposited using a nanoline mold, and subsequently, the nanoribbon was suspended through selective plasma etching to obtain the desired twisted yarn structures. Because of the direct formation of TMOs on Ni electrodes, a high energy/power density and excellent electrochemical stability were achieved in asymmetric FS devices incorporating CoNixOy nanoribbon yarns and graphene fibers. Furthermore, a triboelectric nanogenerator, pressure sensor, and flexible light-emitting diode were synergistically combined with the FS. The integration of wearable electronic components, encompassing energy harvesting, energy storage, and powering sensing/display devices, is promising for the development of future smart textiles. Graphical Abstract

High-energy and wearable fiber-shaped asymmetric supercapacitors based on the combination of fluorinated polyimide and Co3O4 on carbon fibers

This study reports a fiber-shaped asymmetric supercapacitor (f-ASC) made from carbonized fluorinated polyimide deposited onto carbon fiber (c-fPI@CF) as a negative electrode coupled with cobalt oxide-embedded c-fPI@CF (Co3O4@c-fPI@CF) as a positive electrode. The thermal decomposition of fPI evolves gases, mostly stemming from the fluorine-containing moiety (–CF3) of fPI. This process leads to the formation of a distinct microporous structure characterized by small graphitic regions and a high specific surface area of 1071 m2 g−1. Asymmetric configuration enlarges the operating voltage of the f-ASC, contributing to the increase in energy density. The resulting f-ASC shows a capacitance of 56 F cm−3 at 0.5 A cm−3, exceeding other fiber supercapacitors and good cycle stability even under mechanical deformation, demonstrating its feasibility as a wearable power source. It also delivers a significant energy density of 10.0 mWh cm−3 and a power density of 1.16 W cm−3. According to first-principles calculations, the graphitic structure of c-fPI increases the conductivity of Co3O4@c-fPI and stabilizes the exposed metal spots of the Co3O4. Therefore, this f-ASC exhibits great potential for future wearable energy storage systems.

Core-shell heterostructured Ni(OH)2@activation Zn-Co-Ni layered double hydroxides electrode for flexible all-solid-state coaxial fiber-shaped asymmetric supercapacitors

The increasing requirements for wearable and portable electronics are driving the interests of high performance fiber supercapacitor. Layered double hydroxide (LDH) is broadly used in electrode materials, owing to the adjustability of components and the unique lamellar structure. However, limited active sites and poor electrical conductivity hinder its applications. Herein, the core–shell heterostructured Ni(OH)2@activation Zn-Co-Ni layered double hydroxides (Ni(OH)2@A-ZnCoNi-LDH) electrode was fabricated by loading pseudocapacitance material on the A-ZnCoNi-LDH to improve the electrochemical performance. Significantly, benefits from the synergistic effect of the multi-metal ions and the core–shell heterostructure, the electrodes demonstrated a capacitance of 2405 mF·cm−2 at 1 mA·cm−2. Furthermore, Ni(OH)2@A-ZnCoNi-LDH was used as the core electrode and carbon nanotube (CNT) film coated with Fe2O3@reduced graphene oxide (rGO) was wrapped around the core electrode to assemble coaxial fiber asymmetric supercapacitor, which illustrated an ultrahigh energy density of 177.7 µWh·cm−2 at 0.75 mW·cm−2. In particular, after consecutive charging and discharging 7000 cycles, the capacitance retention of the device was 95 %, indicating the excellent cycling stability. Furthermore, the device with high flexibility can be woven into textiles in different shapes. The fabricated device has an excellent development prospect as an energy source in wearable electronic devices.

Aminated silver nanowires as current collectors and binders for the preparation of multilayer graphite loading high-performance silk fiber electrodes

The rapid development of wearable electronic devices has put forward high requirements for their energy storage devices. Currently, fiber supercapacitors have attracted widespread attention owing to their miniature sizes and high flexibility, but an improvement in their electrochemical performance is often limited by the loading of conductive energy storage materials. Herein, a multilayer graphene loading strategy based on amino silver nanowires (NH2-AgNWs) was developed to prepare silk electrodes, wherein NH2-AgNWs were used as current collectors and binders to increase the conductivity of silk electrodes and achieve multilayer loading graphene on silk. The prepared silk electrode exhibited a high specific capacitance of 37.14 mF/cm because of the multilayer loading of the conductive energy storage material. The generality of this method is further demonstrated with a cotton thread substrate electrode, which exhibited a specific capacitance of 69.45 mF/cm. Additionally, a parallel fiber-shaped supercapacitor (PFSS) was assembled, at the maximum power density of 74.48 mW/m2, the energy density reaches 1468.87 mWh/m2. The PFSS exhibited a capacitance retention rate of 93.01 % when the bending degree was 90°. This study proposes a multilayer graphene loading strategy based on NH2-AgNWs for the preparation of fiber electrodes and a flexible fiber supercapacitor was assembled.

Stretchable flexible fiber supercapacitors for wearable integrated devices

PANI-TPU films were prepared by electrostatic spinning and in situ polymerization, and a fiber supercapacitor that maintains stable performance under large tensile deformation conditions can be realized by twisting.

Structurally oriented black phosphorus/MXene heterostructured fibers for flexible supercapacitors with enhanced ion transport and capacitive charge storage

Structurally oriented BP/Ti3C2Tx heterostructured fibers with high conductivity, excellent mechanical properties and high specific capacitance were fabricated via electrostatic assembly for high-performance flexible fiber supercapacitors.

Wide Temperature All-Solid-State Ti3 C2 Tx Quantum Dots/L-Ti3 C2 Tx Fiber Supercapacitor with High Capacitance and Excellent Flexibility.

Ti3 C2 Tx Quantum dots (QDs)/L-Ti3 C2 Tx fiber electrode (Q3 M7 ) with high capacitance and excellent flexibility is prepared by a wet spinning method. The assembled units Ti3 C2 Tx nanosheets (NSs) with large size (denoted as L-Ti3 C2 Tx ) is obtained by natural sedimentation screen raw Ti3 AlC2 , etching, and mechanical delamination. The pillar agent Ti3 C2 Tx QDs is fabricated by an ultrasound method. Q3 M7 fiber electrode gave a specific capacitance of 1560 F cm-3 , with a capacity retention rate of 79% at 20 A cm-3 , and excellent mechanical strength of 130 Mpa. A wide temperature all-solid-state the delaminated montmorillonite (F-MMT)/Polyvinyl alcohol (PVA) dimethyl sulfoxide (DMSO) flexible hydrogel (DHGE) (F-MMT/PVA DHGE) Q3 M7 fiber supercapacitor is assembled by using Q3 M7 fiber as electrodes and F-MMT/PVA DHGE as electrolyte and separator. It showed a volume specific capacitance of 413 F cm-3 at 0.5 A cm-3 , a capacity retention of 97% after 10000 cycles, an energy density of 36.7 mWh cm-3 at a power density of 311mW cm-3 , and impressive capacitance and flexibility over a wide temperature range of -40 to 60°C. This work provides an effective strategy for designing and assembling wide temperature all-solid-state fiber supercapacitors with optimal balance of capacitive performance and flexibility.

Rheology Engineering for Dry-Spinning Robust N-Doped MXene Sediment Fibers toward Efficient Charge Storage.

MXene nanosheets are believed to be an ideal candidate for fabricating fiber supercapacitors (FSCs) due to their metallic conductivity and superior volumetric capacitance, while challenges remain in continuously collecting bare MXene fibers (MFs) via the commonly used wet-spinning technique due to the intercalation of water molecules and a weak interaction between Ti3 C2 TX nanosheets in aqueous coagulation bath that ultimately leads to a loosely packed structure. To address this issue, for the first time, a dry-spinning strategy is proposed by engineering the rheological behavior of Ti3 C2 TX sediment and extruding the highly viscose stock directly through a spinneret followed by a solvent evaperation induced solidification. The dry-spun Ti3 C2 TX fibers show an optimal conductivity of 2295 S cm-1 , a tensile strength of 64MPa and a specific capacitance of 948 F cm-3 . Nitrogen (N) doping further improves the capacitance of MFs to 1302 F cm-3 without compromising their mechanical and electrical properties. Moreover, the FSC based on N-doped MFs exhibits a high volumetric capacitance of 293 F cm-3 , good stability over 10000 cycles, excellent flexibility upon bending-unbending, superior energy/power densities and anti-self-discharging property. The excellent electrochemical and mechanical properties endow the dry-spun MFs great potential for future applications in wearable electronics.

Carbonized paper-supported electrode with covalent organic framework layers on carbonized cellulose fibers for supercapacitor application

As a class of crystalline porous polymers, covalent organic frameworks (COFs) have shown great application potential in electrochemical energy storage due to their high specific surface area, porous structure, and multiple redox-active sites. However, there are some challenges for practical application of COFs, such as low electrical conductivity, easy stacking, weak mechanical strength, and poor processability. In this study, 2,6-diaminoanthraquinone-1,3,5-triformylphloroglucinol COF is synthesized on dialdehyde cellulose fibers with hyperbranched polyamide-amine (HPAMAM) as a stabilizer. After carbonization, the COF is uniformly and stably supported on the conductive carbon fibers (CCFs) for preparing composite paper electrode (CCF-HPAMAM-COF paper). The carbonized fibers provide mechanical support for the COF and improve the electron transfer efficiency. While the COF layers shorten the ion diffusion path for high utilization of redox-active sites due to their porous structure, the CCF-HPAMAM-COF paper exhibits high volume-specific capacitance (66.7 F/cm3 at 0.5 mA/cm2), good rate capability (capacitance retention of 82% with 10 times current density), and a long lifetime (a charge-discharge stability of 93.7% after 10,000 cycles). This work develops a carbonized paper-supported electrode with stable loading of COFs on carbonized fibers for new generation sustainable supercapacitors.

Different assembled nano-MnO2 fiber supercapacitors applied for smart wearable clothing

With rapid development in the smart wearable field, new-style flexible energy storage devices are necessary to satisfy the demands of flexible smart clothing. Thereinto, fiber supercapacitors present promising application prospects. This work puts forward a facile and reliable strategy to fabricate coaxial fiber electrodes via binary wet spinning, and further assembles them into parallel or twisted nano-MnO2 fiber supercapacitors. In the obtained fiber electrode, a carboxymethylcellulose layer onto nano-MnO2 not only allows the requisite ion exchange between the electrochemical active materials and gel electrolyte, but also plays the role of separator to protect the two fiber electrodes effectively from contacting a short circuit, greatly ensuring the electrochemical stability of the nano-MnO2 fiber supercapacitors. The parallel nano-MnO2 fiber supercapacitor reaches a maximum CL of 19.7 μF/cm, EL of 0.0027 μWh/cm and PL of 1.49 μW/cm; the twisted MnO2 fiber supercapacitor achieves maximum CL, EL and PL of 49 μF/cm, 0.0053 μWh/cm and 1.0 μW/cm, respectively. Besides, the outstanding softness and tensile properties of the obtained nano-MnO2 fiber supercapacitors also guarantee stable electrochemical performance under bending, knotting or other large-distortion situations, which is beneficial to develop a new generation of metal oxide fiber supercapacitors for smart wearable clothing.

How Practical Are Fiber Supercapacitors for Wearable Energy Storage Applications?

Future wearable electronics and smart textiles face a major challenge in the development of energy storage devices that are high-performing while still being flexible, lightweight, and safe. Fiber supercapacitors are one of the most promising energy storage technologies for such applications due to their excellent electrochemical characteristics and mechanical flexibility. Over the past decade, researchers have put in tremendous effort and made significant progress on fiber supercapacitors. It is now the time to assess the outcomes to ensure that this kind of energy storage device will be practical for future wearable electronics and smart textiles. While the materials, fabrication methods, and energy storage performance of fiber supercapacitors have been summarized and evaluated in many previous publications, this review paper focuses on two practical questions: Are the reported devices providing sufficient energy and power densities to wearable electronics? Are the reported devices flexible and durable enough to be integrated into smart textiles? To answer the first question, we not only review the electrochemical performance of the reported fiber supercapacitors but also compare them to the power needs of a variety of commercial electronics. To answer the second question, we review the general approaches to assess the flexibility of wearable textiles and suggest standard methods to evaluate the mechanical flexibility and stability of fiber supercapacitors for future studies. Lastly, this article summarizes the challenges for the practical application of fiber supercapacitors and proposes possible solutions.

Nacre-Inspired Strong MXene/Cellulose Fiber with Superior Supercapacitive Performance via Synergizing the Interfacial Bonding and Interlayer Spacing.

MXene fibers are promising candidates for weaveable and wearable energy storage devices because of their good electrical conductivity and high theoretical capacitance. Herein, we propose a nacre-inspired strategy for simultaneously improving the mechanical strength, volumetric capacitance, and rate performance of MXene-based fibers through synergizing the interfacial interaction and interlayer spacing between Ti3C2TX nanosheets. The optimized hybrid fibers (M-CMC-1.0%) with 99 wt % MXene loading exhibit an improved tensile strength of ∼81 MPa and a high specific capacitance of 885.0 F cm-3 at 1 A cm-3 together with an outstanding rate performance of 83.6% retention at 10 A cm-3 (740.0 F cm-3). As a consequence, the fiber supercapacitor (FSC) based on the M-CMC-1.0% hybrid delivers an output capacitance of 199.5 F cm-3, a power density of 1186.9 mW cm-3, and an energy density of 17.7 mWh cm-3, respectively, implying its promising applications as portable energy storage devices for future wearable electronics.

An Implantable Fiber Biosupercapacitor with High Power Density by Multi‐Strand Twisting Functionalized Fibers

AbstractBiosupercapacitors (BSCs) that can harvest and store chemical energy show great promise for power delivery of biological applications. However, low power density still limits their applications, especially as miniaturized implants. Here, we report an implantable fiber BSC with maximal power density of 22.6 mW cm−2, superior to the previous reports. The fiber BSC was fabricated by integrating anode and cathode fibers of biofuel cell with supercapacitor fibers through multi‐strand twisting. This twisting structure endowed many channels inside and high electrochemical active area for efficient mass diffusion and charge transfer among different fibers, benefiting high power output. The obtained thin and flexible fiber BSC operated stably under deformations and performed high biocompatibility after implantation. Eventually, the fiber BSC was implanted subcutaneously in rats and successfully realized electrical stimulation of sciatic nerve, showing promise as a power source in vivo.

An Implantable Fiber Biosupercapacitor with High Power Density by Multi-Strand Twisting Functionalized Fibers.

Biosupercapacitors (BSCs) that can harvest and store chemical energy show great promise for power delivery of biological applications. However, low power density still limits their applications, especially as miniaturized implants.Here, we report an implantable fiber BSC with maximal power density of 22.6 mW‧cm-2, superior to the previous reports. The fiber BSC was fabricated by integrating anode and cathode fibers of biofuel cell with supercapacitor fibers through multi-strand twisting. This twisting structure endowed many channels inside and high electrochemical active area for efficient mass diffusion and charge transfer among different fibers, benefiting high power output. The obtained thin and flexible fiber BSC operated stably under deformations and performed high biocompatibility after implantation. Eventually, the fiber BSC was implanted subcutaneously in rats and successfully realized electrical stimulation of sciatic nerve, showing promiseas a power source in vivo.

Truly form-factor–free industrially scalable system integration for electronic textile architectures with multifunctional fiber devices

An integrated textile electronic system is reported here, enabling a truly free form factor system via textile manufacturing integration of fiber-based electronic components. Intelligent and smart systems require freedom of form factor, unrestricted design, and unlimited scale. Initial attempts to develop conductive fibers and textile electronics failed to achieve reliable integration and performance required for industrial-scale manufacturing of technical textiles by standard weaving technologies. Here, we present a textile electronic system with functional one-dimensional devices, including fiber photodetectors (as an input device), fiber supercapacitors (as an energy storage device), fiber field-effect transistors (as an electronic driving device), and fiber quantum dot light-emitting diodes (as an output device). As a proof of concept applicable to smart homes, a textile electronic system composed of multiple functional fiber components is demonstrated, enabling luminance modulation and letter indication depending on sunlight intensity.

Sewable high-performance poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/layered double hydroxide core-shell fiber electrodes for flexible supercapacitors

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based fibers are one of the most competitive fiber-type electrodes but still suffer from low electrochemical surface areas (ECSAs) and oversensitivity to humidity for fiber supercapacitor applications. Herein, through rational design, a sewable core-shell fiber electrode of PEDOT:PSS/waterborne polyurethane (WPU) fiber wrapped with nickel/cobalt-layered double hydroxides (NiCo-LDH) has been synthesized via wet-spinning and solution reaction. The fiber core acts as a conductive channel for charge carrier transport. The NiCo-LDH shell possesses unique hybrid architectures of honeycomb-like nanosheet array and hollow nanocages, which provide numerous electrochemical active sites. Simultaneously, the water barrier effect of the NiCo-LDH shell and the interaction between Co2+/Ni2+ and PSS reduce fiber water uptake, thus endowing the fiber with a better geometric stability with low swelling ratio. The as-prepared PEDOT:PSS/LDH fiber has a large ECSA (4060 cm2 g−1) and ultrahigh conductivities no matter in dry (1237.3 S cm−1) or wet (1018.7 S cm−1) state. It also exhibits a high capacitance (188.5 F g−1 at 1 A g−1) and long lifespan (capacitance retention of 94% after 10,000 cycles). The fiber-based supercapacitor shows superb flexibility with stable capacitive behavior under deformation. These characteristics manifest the potential of PEDOT:PSS/LDH fibers for stable high-performance energy storage to support wearable electronics.

All-solid-state Ti3C2Tx neutral symmetric fiber supercapacitors with high energy density and wide temperature range

All-solid-state Ti3C2Tx neutral symmetric fiber supercapacitors (PVA EGHG Ti3C2Tx FSCs) with high energy density and wide temperature range are constructed by using polyvinyl alcohol (PVA)-ethylene glycol hydrogel (EGHG)-sodium perchlorate (NaClO4) as electrolyte and separator, and Ti3C2Tx fiber as electrodes. Ti3C2Tx fiber is prepared using 130 mg mL−1 Ti3C2Tx nanosheet ink as an assembly unit in a coagulation bath of isopropyl alcohol (IPA) and distilled water with 5 wt% CaCl2 by a wet spinning method. The prepared Ti3C2Tx fiber exhibits a specific capacity of 385 F cm−3 and a capacitance retention of 94 % after 10,000 cycles in 1 M NaClO4 electrolyte. The assembled PVA EGHG Ti3C2Tx FSCs deliver a specific capacitance of 41 F cm−3, a volumetric energy density of 5 mWh cm−3, and a capacitance retention of 92 % after 500 times continuous bending. Furthermore, it shows good flexibility and excellent capacitance over a wide temperature range of −40 to 40 °C and maintains its electrochemical performance under varying degrees of bending. This study provides a viable strategy for designing and assembling all-solid-state neutral symmetric fiber supercapacitors with high energy density and wide temperature range.