Multifunctional Supercapacitor Research Articles

A stretchable, fully self-healable, temperature-tolerant, and water-proof supercapacitor using TUEG3 capped gold nanosheets on oxime-carbamate bonded polyurethane film and organohydrogel

In this study, we demonstrate a stretchable, fully self-healable, temperature-tolerant, and water-proof supercapacitor with high electrochemical performance via a deliberate selection of materials and device architecture. Distinct from previous works, our whole supercapacitor is stretchable and self-healable, owing to the application of specially devised stretchable and self-healing oxime-carbamate based polyurethane (OC-PU) substrate film, self-healing polymer (poly(ether-thioureas) triethylene glycol) capped Au nanosheet current collector (TUEG3-Au NS) and newly synthesized organohydrogel electrolyte. The fabricated supercapacitor exhibits a high electrochemical performances (specific capacitance of 165.5F g−1, energy density of 14.58 Wh kg−1, power density of 2181.75 W kg−1, and capacitance retention of 89 % after 10,000 cycles) with a capacitance retention of 81 % over stretching by 40 % even after repetitive healing from damages, the self-healing of all components (full self-healing) over repetitive damages with a capacitance recovery by over 83 %, a wide operational temperature range from −20 to 60 °C with retaining over 91 % of capacitance at RT. Furthermore, a μ-LED is stably operated with the supercapacitor immersed in water regardless of the mechanical deformation and self-healing from damage due to self-bonded encapsulation layer of hydrophobic OC-PU film. With a vertically integrated patch device consisting of the fabricated supercapacitor and a strain sensor, bio-signals are detected using the stored energy of the supercapacitor even after self-healing from damages over the temperature range from −20 to 60 °C. This work suggests the high application potential of our high performance multi-functional supercapacitor as an integrated energy storage device for wearable electronics featuring longevity and stability under harsh environments.

Large-Area Fabrication of Porous Graphene Networks on Carbon Fabric via Millisecond Photothermal Processing of Polyaniline for Supercapacitors.

Supercapacitors demonstrate promising potential for flexible, multi-functional energy storage devices; however, their widespread adoption is confronted by fabrication challenges. To access a combination of desirable device qualities such as flexibility, lightweight, structural stability, and enhanced electrochemical performance, carbon fiber (CF) can be utilized as a current collector, alongside graphene as an electrochemically active material. Yet achieving a cost-effective, large-scale graphene production, particularly on CF, remains challenging. Here, a rapid (<1min) photothermal approach is developed for the large-scale production of graphene directly onto CF, utilizing polyaniline (PANI) as a polymer precursor. The in situ electropolymerization of PANI on CF facilitates its rapid synthesis on large areas, followed by conversion into graphene networks, enabling the binder-free fabrication of supercapacitor devices. These devices exhibit an areal capacitance of 180mFcm-2 (at 2mAcm-2 in 1mH2SO4), an order of magnitude higher than other fabric-based devices. Moreover, the devised photothermal strategy allows for one-step preparation of supercapacitor devices on areas exceeding 100cm-2, yielding an absolute areal capacitance of 4.5F. The proportional increase in capacitance with device area facilitates scaling and indicates the commercial viability of this approach for low-cost, energy-efficient, and high-throughput production of lightweight, high-performance graphene-based multi-functional supercapacitor devices.

Structural energy storage system using electrospun carbon nanofibers with carbon nanotubes

AbstractIn the present study, carbon nanofibers containing multi‐walled carbon nanotubes (MWCNTs) were fabricated and employed as electrodes for structural supercapacitors. Carbon nanofibers were utilized as the electrode material in structural supercapacitors to increase the specific surface area. Electrospun polyacrylonitrile (PAN) nanofibers underwent conversion to carbon nanofibers through stabilization and carbonization processes aided by thermal treatment. The specific surface area of the electrospun carbon nanofiber electrodes was further increased approximately 118 times (1946.9 m2/g) using an activation process in comparison with that of non‐activated carbon nanofibers (16.43 m2/g). Multifunctional supercapacitors were fabricated by employing electrospun carbon nanofibers and a vacuum resin infusion technique. The specific capacitance of activated carbon nanofibers (ACNF) and ACNF‐MWCNT exhibited significant improvement (14.87 and 48.25 mF/cm2, respectively) compared to non‐activated carbon nanofibers (CNF‐MWCNT: 1.71 mF/cm2). This improvement was attributed to the reduction in equivalent series resistance and the increase of the surface area of the nanofiber electrodes. Additionally, the carbon nanofiber electrodes contributed to an increased interlaminar fracture toughness of structural supercapacitors, acting akin to “Velcro” between fabric interfaces. This work serves as a “proof of concept” for a straightforward and efficient method to manufacture electrodes for structural supercapacitors based on the electrospinning technique.Highlights Fabrication of carbon nanofibers containing MWCNTs using electrospinning. The carbon nanofiber as an electrode for structural supercapacitors. Simple and effective method. Dramatically improving specific capacitance of the supercapacitors.

Ti3C2Tx MXene coated carbon fibre electrodes for high performance structural supercapacitors

MXenes, while excellent for electrical energy storage, face challenges in translating their nanoscale properties to macroscale structures. To address this, MXene-coated carbon fibers (CF) were developed as electrode materials for structural supercapacitor composites. CF surface chemistry was tailored using aryl diazonium salts (–NO2, –NH2, -SH, –COOH) to optimize MXene adhesion. Electrodes were characterized for surface chemistry, morphology, and properties including electrochemical, mechanical, and interfacial aspects. Electrodes developed from MXene coated on CF functionalized with a poly(o-phenyelenediamine) coating exhibited a specific capacitance of 157 F/g−1 at 5 mV s−1, a ∼725-fold improvement in capacitance compared to pristine unfunctionalized CF, with minimal to no compromise in the underlying strength and stiffness of the CF. The MXene coating also improved the interfacial adhesion of the electrode to an epoxy-based resin by 54 %. The process was scaled up to functionalize and coat woven CF mats and were used to fabricate a structural supercapacitor device. The device exhibited a specific capacitance of 908 mF/g−1 at 0.5 mA g−1, representing a remarkable ∼42-fold improvement compared to the control. This lightweight multifunctional supercapacitor composite holds great potential in aerospace, automotive, and renewable energy storage sectors, addressing global challenges tied to fossil fuel combustion and associated environmental and socio-economic issues.

Structural supercapacitor electrodes for energy storage by electroless deposition of MnO2 on carbon nanotube mats

Structural supercapacitors have great potential for the future of electric-powered vehicles and mobile robots, as they can serve a dual purpose of providing structural integrity and storing electric energy. However, a significant challenge in the development of these energy storage structures is the creation of electrodes that are mechanically strong and stiff. Herein, we report an electroless technique for depositing pseudocapacitive manganese dioxide (MnO2) uniformly throughout carbon nanotube (CNT) mats, resulting in multifunctional supercapacitor electrodes with simultaneously enhanced mechanical and electrochemical properties. The deposited MnO2 nanoporous material acts as a structural matrix supporting the CNTs, thus improving the strength and stiffness. Furthermore, the uniform distribution of MnO2 nanoparticles throughout the substrate reduces the through-thickness electrical resistance and achieves outstanding rate capability. With the optimum loading of MnO2 95 wt%, which gives the highest strength, the total capacitance of the electrode material increased by nine times compared to the baseline material, while the tensile strength and stiffness were improved by 110% and 430%, respectively. Employing these high-performance electrodes in supercapacitors results in improved device-level performance. Specifically, the optimum loading of MnO2 increased the device's energy density by around 100 times without compromising the power density. These new high-performance structural electrodes represent a promising technology that could accelerate the practical application of energy storage composite structures.

Highly self-adhesive, compressible, stretchable, all hydrogel-based supercapacitor for wearable/portable electronics

The increasing popularity of portable/wearable multifunctional electronic devices has highlighted the need for multifunctional power-supply devices. To fulfill this need, we firstly designed a highly self-adhesive and deformable polyacrylamide-based hydrogel electrode. Inspiration by mussels, nanofillers with the design of confined nanospace that formed by the composite of polydopamine-reduced graphene oxide and a compound of cobalt-nickel bimetal oxide and cobalt nitride was involved in the as-prepared hydrogel electrode. This design endows the as-prepared electrode with both the impressive self-adhesive property as well as electrochemical performance. Secondly, a multifunctional all hydrogel-based supercapacitor was assembled by the same as-prepared polyacrylamide hydrogel matrix of electrodes and an electrolyte. The self-adhesive property of both electrode and electrolyte provides a tightly connected interface to ensure structural stability and results in a highly electrical stability during different deformations. Moreover, this multifunctional all hydrogel-based supercapacitor can adhere to the tissue and be used as a functional electronic component as both energy storage and power-supply device. This designed multifunctional supercapacitors can provide insights for further strategies to address energy storage alternatives for portable/wearable electronics.

A multifunctional paper-based supercapacitor with excellent temperature adaptability, plasticity, tensile strength, self-healing, and high thermoelectric effects

In recent years, the development of multi-functional supercapacitors with high flexibility and strong environmental adaptability has gradually become a focus of attention.

Multifunctional supercapacitor integrated sensor from Oyster and Cicada derived bio-ternary composite: Vanillin/caffeine detections in beverages

This study focused bio-materials composite mediated supercapacitor integrated vanillin and caffeine sensor system. The biomaterials isolated from Oyster shell and Cicada exoskeletons. The isolated chitins are functionalized with Tungsten disulfide/Polypyrrole (WS2/PPy) composite via one-step hydrothermal technique. The elemental, structural, and morphological analyses are conducted with FTIR, XRD, XPS, SEM and TEM. The XPS spectra are exhibit important peaks of S2p, W3d, N1s and C1s. The Oyster chitin/polypyrrole/WS2 composite supercapacitor-sensor electrode archives a specific capacitance of 381.5 Fg−1 and sensitivity for vanillin and caffeine are 0.021 μA μg−1 mL cm−2 and 0.014 μA μg−1 mL cm−2. The Cicada-chitin/PPy/WS2 composite delivers 311.3 Fg−1 of specific capacitance with sensitivity of vanillin is 0.013 μA μg−1 mL cm−2 and caffeine is 0.01 μA μg−1 mL cm−2. Cycling tests show good capacitance retention of 90% up to 100,000 cycles. The performances of bio-mass supercapacitor combined vanillin/caffeine sensor system tested in food and beverage samples. This system provides a feasible route for potentially applicable status in smart electronic devices in the food and beverage industries.

Recent progress in multifunctional hydrogel-based supercapacitors

Hydrogel-based supercapacitors with excellent mechanical properties can overcome several unsettled challenges that current wearable power supply devices confront as a result of the distinctive dense intriguing nanostructures of hydrogels, which serve as an ideal candidate with durability and reliability for supplying power to truly wearable electronics. More importantly, benefiting from the broadly tunable physicochemical characterizations, the hydrogel electrolyte components with high ionic conductivity could possess several additional functions including ultrahigh stretchability, strong self-healability, and low-temperature tolerance, which qualifies these multifunctional supercapacitors for application in a variety of extreme working environments, especially in significant deformations caused by human-motion, conditions of applied destructive external force, and extremely frigid circumstances. Herein, the state-of-the-art advanced multifunctional supercapacitors are discussed, focusing on the introductions and explanations of particularly functionalized hydrogel electrolytes, ultra-flexible textile-based electrodes or hydrogel-based electrodes, and the combination strategies of electrolytes and electrodes.

MXene loaded onto clean wiper by a dot-matrix drop-casting method as a free-standing electrode for stretchable and flexible supercapacitors

MXene-loaded textiles can be used as free-standing electrodes for multi-functional supercapacitors (SCs), due to their good conductivity, high electrochemical activity, excellent flexibility, and stretchability. However, the typically self-restacking phenomenon would emerge with the increase in MXene amount, resulting in a significant reduction of the ion-accessible surface areas and active sites of MXene. Herein, a dot-matrix drop-casting method with the advantages of quickness and high uniformity is developed to load high amount (6.1 mg cm−2) of Ti3C2 (a typical MXene) on a clean wiper (CW, a typical textile), and simultaneously to alleviate the resultantly self-restacking phenomenon of Ti3C2. The results show that the obtained composite (CWM) has a high conductivity of 2.3 S cm−1 and large specific capacitance of 282 mF cm−2 at 1 mA cm−2, whereas it remains a high tensile strength of 20.1 MPa and developed porous structure (33.4 m2 g−1). These attractive properties make CWM an ideal free-standing electrode. Further, CW is used as a separator to fabricate an all-CW-derived SC (CWM//CW//CWM), because its porous structure provides abundant routes for facile ion transport. Such a SC has an excellent rate capability with a high capacitance retention of 78.2% from 1 to 20 mA cm−2, large specific capacitance of 118 mF cm−2 at 1 mA cm−2, and high energy density of 10.1 μWh cm−2 at 389.9 μW cm−2. Moreover, an all-solid-state SC (CWM//CWM) is fabricated, and shows an excellent stability on capacitive behaviors during bending (0–120°) or stretching (10–40% strains), manifesting its great potential on wearable and portable electronics.

Stretchable, self-healable, and photodegradable supercapacitor based on a polyelectrolyte crosslinked via dynamic host-guest interaction

We report on the fabrication of a high performance multi-functional supercapacitor which is intrinsically stretchable, self-healable, and photodegradable. A repeatedly stretchable (500 times), photodegradable hydrogel that self-heals quickly at room temperature without any trigger is synthesized by crosslinking of azobenzeno-polyacrylamide (Azo-PAM) and water-soluble α-cyclodextrin polymer (α-CDP) via dynamic host-guest interaction. With the Azo-PAM/α-CDP/LiCl hydrogel as polyelectrolyte, the stretchable, self-healable, and photodegradable supercapacitor is fabricated. After complete bisection, the supercapacitor recovers its electrochemical performance by physical contact in air-ambient conditions and maintains its performance upon multiple cycles of self-healing at a single bisected location. It also maintains elastic performance even after repeated stretching and self-healing. Finally, the supercapacitor exhibits photodegrading performance, dissolving in water upon UV-irradiation after use. This work demonstrates the superior performance and high potential of our newly devised stretchable, self-healable, and photodegradable supercapacitor as a smart energy storage device for next-generation durable and eco-friendly wearable electronics.

A proof of concept of a structural supercapacitor made of graphene coated woven carbon fibers: EIS study and mechanical performance

A multifunctional supercapacitor based on a graphene nanoplatelet (GNP) coated woven carbon fiber (WCF) composite has been manufactured and its electrochemical and mechanical performance has been evaluated. Specific capacitance from voltammetry tests is about three times higher than the non-coated WCFs and several orders of magnitude above neat polymer WCF composites. Furthermore, an electrochemical impedance spectroscopy (EIS) analysis has been carried out in the coated and non-coated WCF capacitors. The equivalent circuit consisted on a series/parallel resistance/constant phase elements. EIS results show that the coated samples have superior capacitor properties, confirmed by chronoamperometry tests. The values of energy and peak power densities were also significantly higher in the coated WCFs, proving higher capabilities as supercapacitors. In addition, mechanical performance of structural supercapacitor is affected by the simultaneous addition of a polymer electrolyte and GNPs, with a reduction of mechanical strength when compared to neat polymer composites. However, and due to the lower viscosity of the electrolyte, there is a higher compaction of the material promoting an increase of WCF volume fraction on the LY-PEGDGE matrix samples, leading to similar values of Young Modulus. Despite the detriment of mechanical properties, they were far above other WCF-based structural supercapacitors. The proof of concept by illuminating a LED was highly successful, proving promising capabilities as structural supercapacitors.

Two-birds-one-stone: multifunctional supercapacitors beyond traditional energy storage

A comprehensive overview on the recent progress of multifunctional supercapacitors which combine energy storage capability with other functions.

Functional hydrogel-based supercapacitors for wearable bioelectronic devices

Functional hydrogel-based electrodes and electrolytes for multifunctional supercapacitors for wearable bioelectronic devices.

High performance organic-inorganic hybrid material with multi-color change and high energy storage capacity for intelligent supercapacitor application

As a kind of multifunctional supercapacitor, electrochromic-supercapacitor device (ESD) can be used to visually estimate the energy storage level of the device through the color change. Currently, low energy storage capacity limits the practical application of ESD. Here, WO3 with oblate shape morphology formed by the aggregation of nanoclusters is successfully prepared by hydrothermal synthesis. Then WO3-poly (5-cyanoindole) (P5ICN/WO3) hybrid material is obtained by electrochemical polymerization P5ICN on the surface of WO3. Due to the synergistic effect of P5ICN and WO3, P5ICN/WO3 hybrid material shows enhanced charge transfer rate, multi-colors change (blue-green, yellow and green) and good supercapacitive properties (specific capacitance is 89.2 mF cm−2). An asymmetric ESD is successfully constructed based on P5ICN/WO3, which also shows good electrochromic and supercapacitive properties, such as high specific capacitance, energy density and power density. The color of ESD can change between yellow and dark green during charge-discharge process. In practical application, the intelligent monitoring of the energy storage state of device is achieved by the color variations or transmittance change of this ESD. And the charged ESD also can power a LED, indicating the feasibility of practical application.

Multifunctional Supercapacitors: Rational Design of Nanostructured Electrode Materials toward Multifunctional Supercapacitors (Adv. Funct. Mater. 2/2020)

Multifunctional Supercapacitors: Rational Design of Nanostructured Electrode Materials toward Multifunctional Supercapacitors (Adv. Funct. Mater. 2/2020)

A multifunctional supercapacitor based on 2D nanosheets on a flexible carbon nanotube film.

The manufacture of multifunctional and high-performance wearable supercapacitors (SCs) requires a new class of flexible electrodes with high conductivity, high mechanical stability, good water-proof ability and self-healable capability. Herein, we report a stretchable and self-healable SC based on a MoS2/PEDOT/CNT electrode. The specific capacitance of the SC could be retained up to 81.98% even after the 21st breaking/healing cycle. Furthermore, a sheet-type asymmetric supercapacitor (ASC) based on a MoS2/PEDOT/CNT positive electrode and SnS2/CNT negative electrode is constructed, and it exhibits high performance with an extended potential window of 1.7 V, areal capacitance of 103.76 mF cm-2 at 1.5 mA cm-2, and outstanding stability with no capacitance degradation under a wide range of bending conditions. The ASC is sealed by polyimide films, and it shows high electrochemical stability in hot water and under high speed centrifugation conditions, indicating good water-proof ability and wearability. The as-prepared ASC is also encapsulated in elastic films to provide 225% stretchability. The ASC devices packaged in all these ways exhibit high capacitance retention (>90%) under various bending and dynamic conditions.

Lightweight Kevlar‐Reinforced Graphene Oxide Architectures with High Strength for Energy Storage

AbstractA multifunctional supercapacitor based on reduced graphene oxide (rGO) hydrogels deposited onto Kevlar fibers and woven cloth is reported, which exhibits both excellent mechanical performance and electrochemical energy storage. The specific strength of rGO hydrogel–Kevlar fibers reaches 1.6 MPa m3 kg−1 and the specific capacitance is 57 F g−1 with 38.1% of rGO. Such high specific strength is comparable to one of the as‐received Kevlar fibers (2.0 MPa m3 kg−1), indicating that the gelation process does not harm the fibers. The gel‐state symmetric device based on rGO hydrogel–Kevlar cloth survives impact from a 9.1 N force from a falling metal ball as well as deformation during bending to 90°. The high specific strength is due to the Kevlar while the specific capacitance stems from the 3D interconnected macrostructure of rGO hydrogels. To demonstrate the combination of these properties, a multifunctional efficiency is introduced based on the geometric average of mechanical and energy storage properties as compared to epoxy and carbon aerogel supercapacitor, respectively. This metric predicts an optimum combination or properties at a volume ratio of Kevlar/rGO gel between 0.0008 and 0.35.

Rational Design of Nanostructured Electrode Materials toward Multifunctional Supercapacitors

AbstractAs an intermediate step during energy usage, supercapacitors with superior power density, long‐term cycling stability, and moderate energy density have attracted immense interest as a facile route to use energy in a clean, efficient, and versatile manner in smart grid applications, as well as portable devices and other applications. Currently, the major drawback of supercapacitors is the low energy density. Electrode materials are the key components determining the cell performance. Great research efforts are made to develop nanostructured electrode materials with high performance. On the other hand, integrating supercapacitors with other applications have led to the emergence of many new types of multifunctional supercapacitors, which are attractive for a myriad of applications. The current understanding on charge/discharge mechanisms of electric double layer capacitors and pseudo‐capacitors is discussed along with recent development in designing nanostructured electrode materials by structure/morphology engineering, doping, and crystal structure controlling. Achievements in multifunctional supercapacitors like flexible supercapacitors, all‐solid‐state supercapacitors, self‐healing supercapacitors, electrochromic supercapacitors, self‐chargeable supercapacitors, and supercapacitors integrated with sensors are illustrated. Finally, opportunities and challenges in developing high performance and multifunctional supercapacitors are proposed.

Superb Electrolyte Penetration/Absorption of Three-Dimensional Porous Carbon Nanosheets for Multifunctional Supercapacitor

High specific surface area and reasonable pore-size distribution are conducive to promote the energy density and power density of carbon based supercapacitors. Nevertheless, the permeability of electrolyte is a prerequisite condition for surface storage charge and the ion diffusion in multiscale pores. Therefore, improving the electrolyte penetration/absorption is particularly important. Herein, we reported a novel three-dimensional porous ultrathin carbon nanosheet (3DPAC) with considerable electrolyte penetration/absorption property, which was proven by experiment and theory. The 3DPAC was prepared from abundant biomass waste wood dust via hydrothermal and carbonized treatment and characterized with ultrathin nanosheets, abundant porous structure, and rich N, O dopant. This unique three-dimensional and hierarchical porous structure leads to robust conduction of electrons and the penetration/absorption of electrolyte ions, which endow the 3DPAC with approved electrochemical properties. The supercapacitor...