Flexible Micro-supercapacitors Research Articles

Facile fabrication of flexible and adhesive micro-supercapacitor tapes from conducting polymer solution for self-powered wearable sensing system

Flexible micro-supercapacitor (MSC) with in-plane electrodes has attracted significant attention as microscale energy storage device. Especially, flexible MSCs with adhesion properties are of great interest for wearable electronics. Here, we demonstrate a facile and cost-effective mask-assisted drop-casting method to fabricate adhesive MSC on medical tape using dimethyl sulfoxide (DMSO) doped poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) aqueous solution. The fabricated MSC with poly (vinyl alcohol)/H3PO4 gel electrolyte exhibits an areal specific capacitance of 10.96 mF cm−2 at a current density of 0.1 mA cm−2 with excellent mechanical flexibility. The MSC can be attached on various substrates due to the stickiness of the medical tape. For practical application, the MSC can be coupled with a solar cell to achieve a stand-alone power supply system for a flex senor in monitoring finger movements. Therefore, we believe that the mask-assisted drop-casting method paves a new way to develop flexible and adhesive MSCs for self-powered integrated wearable electronics.

Laser-patterned PEDOT:PSS-aramid nanofiber composite electrodes for in-plane supercapacitors with high performance, shape-diversity and ultrahigh deformation resistance

The rapid development of portable and wearable modern electronics is in urgent need of the compatible energy storage devices, among which the flexible in-plane micro-supercapacitor (MSC) has emerged as a promising candidate. In this work, a facile and efficient laser-ablation technique was used to fabricate high performance metal-free all-solid-state in-plane MSCs with dimethyl sulfoxide-treated composite electrode (D-PA) composed of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS, PH1000) and aramid nanofibers. The effect of D-PA mass loading on the electrical and electrochemical properties of electrodes and devices was studied. The optimal MSC delivers high areal capacitance (15.4 mF/cm2 at 2 mV/s), superior charge/discharge cycling stability (capacitance hardly changes after 10,000 cycles), excellent rate performance (11.1 mF/cm2 at 3 mA/cm2) and ultrahigh resistance to arbitrary and extreme mechanical deformation (including circle-bending, free-twisting and multi-folding), which are superior to many state-of-the-art PH1000-based MSCs. Furthermore, performance of the shape-diverse device is easily tailored by series and/or parallel integration without usage of the metallic component. Such high performance MSC presents a great potential application in portable and wearable electronics even under severe deformed states.

Effect of thermal annealing on electrochemical and morphological properties of printed NiO electrodes for flexible asymmetric micro-supercapacitor applications

We report the effects of thermal annealing on screen-printed NiO electrodes for asymmetric battery-type supercapacitors on flexible substrates. Ni(OH)2 was synthesized and annealed at 300 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C to obtain six morphologically diverse NiO samples. FE-SEM, XRD, BET, and four-probe measurements were used to investigate their morphology, crystallinity, surface area, and conductivity, respectively. Six symmetric supercapacitors were screen-printed on a PET substrate with 1 M H2SO4 electrolyte to probe their electrochemical properties. NiO annealed at 400 °C (NiO-400) demonstrated the highest areal capacitance of 19.54 mF/cm2 coupled with reduced charge-transfer resistance, consistent with the highly porous yet continuous structure observed via FE-SEM and BET surface analysis. With this, an inter-digital asymmetric supercapacitor with NiO-400 cathode and graphene anode was fabricated to demonstrate high areal capacitance of 26.42 mF/cm2, a wide potential window of 1.5 V (at 97.3% coulombic efficiency) and excellent flexibility with 96.4% retention (180°) after 1000 cycles.

Biologically inspired anthraquinone redox centers and biomass graphene for renewable colloidal gels toward ultrahigh-performance flexible micro-supercapacitors

Biomass carbon and small redox biomolecules are attractive materials for green, sustainable energy storage devices owing to their environmentally friendly, low-cost, scalable, and novel sources. However, most devices manufactured using these materials have low specific capacitance, poor cycle stability, short lifetime, complexity, and low precision of device fabrication. Herein, we report the directed self-assembly of mononuclear anthraquinone (MAQ) derivatives and porous lignin-based graphene oxide (PLGO) into a renewable colloidal gel through noncovalent interactions. These self-assembled gel electrode materials exhibited high capacitance (484.8 F g−1 at a current density of 1 A g−1) and could be further printed as flexible micro-supercapacitors (FMSCs) with arbitrary patterns and a relatively high resolution on specific substrates. The FMSCs exhibited excellent areal capacitance (43.6 mF cm−2), energy and power densities (6.1 μWh cm−2 and 50 μW cm−2, respectively), and cycle stability (> 10,000 cycles). Furthermore, the printed FMSCs and integrated FMSC arrays exhibited remarkable flexibility while maintaining a stable capacitance. The proposed approach can be applied to other quinone biomolecules and biomass-based carbon materials. This study provides a basis for fabricating green and sustainable energy storage device architectures with high capacitance, long-term cycling, high scalability, and high precision.

Laser induced flexible micro-supercapacitor for pressure sensing

Portable, wearable electronic devices have spurred the rapid development of flexible and stretchable energy harvesting/storage devices with high energy density, superior mechanical stability, and long cycle life. Micro-supercapacitor (MSC) has attracted wide interest due to their advantages of high power density, rapid charge and discharge, and long cycle life. Fabrication of flexible supercapacitors based on laser induced graphene (LIG) has shown strong advantages and potential for flexible sensor power supply. The purpose of this paper is to propose and develop a laser induced flexible micro-supercapacitor (FMSC) for pressure sensors. FMSC is manufactured from a planar forked finger electrode made of graphene induced by CO2 laser radiation commercial Polyimide (PI) film and PVA polymer gel electrolyte. The FMSCs prepared by this method exhibit good electrochemical properties and excellent mechanical properties. The microscopic morphology of LIG was investigated using SEM, and the optimal laser-induced power was determined to be 12.5%. In this paper, a novel fork-finger electrode pattern was applied to improve the performance of FMSCs by optimizing the structure of planar interdigital electrodes, and the FMSCs prepared at 12.5% power showed excellent supercapacitance performance at a voltage window of 0.8 V with a specific capacitance of 2.21 mF/cm2. The FMSCs were made by assembling commercial PI films, PVA, and H3PO4 simple materials, which makes it possible to prepare FMSCs at low cost and high efficiency based on laser direct writing technology. FMSCs provide energy to the flexible sensors and continuously collect energy to charge FMSCs through an integrated flexible energy harvester, which makes FMSCs promising for flexible self-powered wireless sensing platforms.

From cotton to functional flexible transparent film for printable and flexible microsupercapacitor with strong bonding interface

A novel functional flexible transparent film with excellent printability, swellability, degradability, and hydroxyl groups is directly developed from natural cotton.

Laser-induced graphene and its modification with polypyrrole for increasing microsupercapacitor capacitance

Laser-induced graphene (LIG) films were synthesized by line-by-line scanning of cw CO2 laser focused radiation on the surface of industrial polyimide film as a result of pyrolysis of its near-surface layer. The structure of the synthesized film material is shown to be heterogeneous in thickness by Raman spectroscopy. The results of the study of the effect of the laser power and the distance between the lines on the specific electrical capacitance c of the synthesized material in aqueous solution of sulfuric acid are presented. It is shown that modification of LIG with polypyrrole (PPy) allows to increase c up to 60 mF/cm2. PPy-modified LIG films were used to make a prototype of a flexible film microsupercapacitor with an area of 8 cm2, using a gel electrolyte based on sulfuric acid and polyvinyl alcohol, with a 230 mF capacitance. Keywords: laser-induced graphene, electric capacitance, polypyrrole, microsupercapacitor.

Лазерно-индуцированный графен и его модификация полипирролом для увеличения емкости микросуперконденсатора

Laser-induced graphene (LIG) films were synthesized by line-by-line scanning of continuous CO2 laser focused radiation on the surface of industrial polyimide film as a result of pyrolysis of its near-surface layer. The structure of the synthesized film material is shown to be heterogeneous in thickness by Raman spectroscopy. The results of the study of the effect of the laser power and the distance between the lines on the specific electrical capacitance c of the synthesized material in aqueous solution of sulfuric acid are presented. It is shown that modification of LIG with polypyrrole (PPy) allows to increase c from up to 60 mF/cm2. PPy-modified LIG films were used to make a prototype of a flexible film microsupercapacitor with an area of 8 cm2 with a gel electrolyte based on sulfuric acid and polyvinyl alcohol with a 230 mF capacitance.

A Ti3C2Tx MXene cathode and redox-active electrolyte based flexible Zn-ion microsupercapacitor for integrated pressure sensing application.

Frequently used aqueous electrolytes in MXene-based Zn-ion hybrid microsupercapacitors (MSCs) limit their cycling and rate stability. The use of metal and nonmetal additives in electrolytes for the performance improvement of Zn-ion MSCs is considered a valid method. Herein, we propose an additive assisted Zn(CF3SO3)2 electrolyte as a redox-active electrolyte to prepare a flexible MXene-based Zn-ion hybrid MSC by a facile spraying method, and it consists of a conductive Ti3C2Tx-LiCl current collector and a Ti3C2Tx-DMSO cathode. In the process of the current density change (from 5 A cm-3 to 30 A cm-3 and then to 5 A cm-3), the capacity retention of the as-fabricated MSC with K3Co(CN)6 additive is over 99.0%, which is higher than 96.7% for the MSC with CKNSe additive and 82.3% for the MSC without an additive. Moreover, the designed MSC with the redox-active K3Co(CN)6 electrolyte exhibits a maximal capacitance retention of 70% after 5000 cycles. Furthermore, the flexible Zn-ion MSC with the Ti3C2Tx MXene cathode and a redox-active electrolyte was used to power a Ti3C2Tx based pressure sensor; the excellent press response of the integrated system not only provides insights into the development of large capacity and long-period stable energy storage devices, but also paves a new way for the development of capacitor-sensor integrated systems.

Paper-based laser-induced graphene for sustainable and flexible microsupercapacitor applications

Laser-induced graphene (LIG) is as a promising material for flexible microsupercapacitors (MSCs) due to its simple and cost-effective processing. However, LIG-MSC research and production has been centered on non-sustainable polymeric substrates, such as polyimide. In this work, it is presented a cost-effective, reproducible, and robust approach for the preparation of LIG structures via a one-step laser direct writing on chromatography paper. The developed strategy relies on soaking the paper in a 0.1 M sodium tetraborate solution (borax) prior to the laser processing. Borax acts as a fire-retardant agent, thus allowing the laser processing of sensitive substrates that other way would be easily destroyed under the high-energy beam. LIG on paper exhibiting low sheet resistance (30 Ω sq−1) and improved electrode/electrolyte interface was obtained by the proposed method. When used as microsupercapacitor electrodes, this laser-induced graphene resulted in specific capacitances of 4.6 mF cm−2 (0.015 mA cm−2). Furthermore, the devices exhibit excellent cycling stability (> 10,000 cycles at 0.5 mA cm−2) and good mechanical properties. By connecting the devices in series and parallel, it was also possible to control the voltage and energy delivered by the system. Thus, paper-based LIG-MSC can be used as energy storage devices for flexible, low-cost, and portable electronics. Additionally, due to their flexible design and architecture, they can be easily adapted to other circuits and applications with different power requirements.Graphical

Bending Resistance Covalent Organic Framework Superlattice: “Nano-Hourglass”-Induced Charge Accumulation for Flexible In-Plane Micro-Supercapacitors

HighlightsCovalent organic framework (COF) superlattices were assembled by free-standing COF nanofilms based on the van der Waals force for the first time.Geometry-induced “nano-hourglass” steric configuration in COF superlattice can provide rapid charge transfer/accumulation at heterojunction interface for in-Plane Micro-supercapacitors.The prepared MSC exhibited a high energy density of 63.2 mWh cm−3 even after high-angle and repeat arbitrary bending from 0 to 180°.

Hierarchical porous nitrogen-doped carbon nanosheets derived from zinc-based bioMOF as flexible supercapacitor electrode

We propose an efficient and flexible supercapacitor electrode material based on hierarchically structured nitrogen-doped graphene-like carbon nanosheets (H-NCNs) with accordion-like shape. H-NCNs were obtained by pyrolyzing zinc-based biometal–organic frameworks (Zn-bioMOFs) and using urea as nitrogen source at high temperature (800 °C) under nitrogen atmosphere, and Zn-bioMOFs were synthesized using biomass molecules, i.e., curcumin. Inheriting from the features of Zn-bioMOF, H-NCNs showed hierarchical structures and unique accordion-like morphology. By changing the urea dosage, the nitrogen-doping degree and porosity of H-NCNs were regulated, optimizing the supercapacitive performance. H-NCNs-8 prepared with Zn-bioMOF/urea mass ratio of 1:8 exhibited high specific capacitance and superior rate capability (293 F g−1 at 0.25 A g−1 and 188 F g−1 at 50 A g−1). The H-NCNs-assembled symmetric supercapacitor offered long cycle life of over 40,000 cycles at 2 A/g and high energy density of 17.6 Wh kg−1 at 250 W kg−1, outperforming most carbon nanomaterial-related ones. Accordingly, the proposed flexible interdigital solid microsupercapacitor demonstrated high areal capacitance, high areal energy densities, and long cycle stability. The present work can provide promising application prospects of MOFs in the field of supercapacitors and flexible electronics.

Flexible in-plane Micro-Supercapacitor Prepared by Laser Annealing and Ablation of a Graphene/Polyamide Acid Composite

An in-plane micro-supercapacitor (MSC) which has a unique interdigitated electrode structure with through-holes was developed by laser annealing and ablation of a carbon/polyamide acid composite coating on a polyimide film. The laser annealing of a composite film consisting of multi-layer graphene or activated carbon remarkably lowered the resistivity by laser carbonization of polyamide acid. The laser ablation was conducted to make an interdigitated electrode with a through-hole structure. The through-holes were effective to improve the capacitance of an in-plane MSC by enhancing the ion diffusion in carbon layer because the surface area of carbon layer can be increased using front and back sides of a polyimide film. An in-plane MSC consisting of an asymmetric interdigitated electrode which had an activated carbon composite layer on the front side and a multi-layer graphene composite on back side of a polyimide film showed the improvement of capacitance.

Stable carbon encapsulated titanium carbide MXene aqueous ink for fabricating high-performance supercapacitors

• A simple method to synthesize phenolic carbon encapsulated Ti 3 C 2 T x (Ti 3 C 2 T x @C) inks • Ti 3 C 2 T x @C exhibited superior oxidation resistance even after 100 days of aging • Ti 3 C 2 T x @C exhibited a specific capacitance of 736 F g –1 in a three-electrode system • A flexible interdigitated micro supercapacitor (MSC) was printed using Ti 3 C 2 T x @C inks • Ti 3 C 2 T x @C MSC device displayed high cycling stability (83% after 10,000 cycles) Ti-based MXenes have shown great promise in electrochemical applications, including (photo)electrocatalysis and energy storage. However, their practical application has been hindered by their rapid oxidation in the presence of water and O 2 . In this work, we propose a method to solve the problem through a one-step hydrothermal treatment of MXene (Ti 3 C 2 T x , where T x is –OH or –F) in the presence of agarose. The hydrothermal treatment results in the in situ capping of the phenolic carbon layer on the Ti 3 C 2 T x to form Ti 3 C 2 T x @C, which improves its chemical stability by protecting the Ti atoms from oxidation with water and O 2 , and thus enhances its electrochemical performance by avoiding re-stacking of the Ti 3 C 2 T x @C sheets. The as-prepared Ti 3 C 2 T x @C exhibits high oxidation resistance with >95% performance when stored in an aqueous medium for at least 100 days. Ti 3 C 2 T x @C provides a specific capacitance of 736 F g –1 in 1 M H 2 SO 4 electrolyte over a voltage window of 0.5 V. Having excellent water dispersibility and high electrochemical activity, Ti 3 C 2 T x @C is ideal for the preparation of stable MXene inks for the fabrication of high-performance interdigitated electrodes through inkjet printing. The flexible micro-supercapacitor constructed from Ti 3 C 2 T x @C ink exhibits excellent cyclic stability up to 10,000 charge-discharge cycles without a significant decrease in specific capacitance.

Hierarchical polypyrrole@cobalt sulfide-based flexible on-chip microsupercapacitors with ultrahigh energy density for self-charging system

Hierarchical polypyrrole@cobalt sulfide-based flexible on-chip microsupercapacitors with ultrahigh energy density for self-charging system

High surface area of crystalline/amorphous ultrathin MnO2 nanosheets electrode for high-performance flexible micro-supercapacitors

Herein, ultrathin MnO 2 nanosheets consisting of crystalline/amorphous phases are prepared by a simple interfacial reaction of surfactant assistance in water-bath with high specific surface area of 317.56 m 2 g −1 , which can accelerate ionic transport and provide more active sites during electrochemical reaction . The as-synthesized MnO 2 nanosheets electrode exhibits remarkable specific capacitance of 163.3 F g −1 at 1 A g −1 in a three-electrode system using 1 M NaSO 4 as electrolyte, and long-term stability with a capacity retention of 89.3% at 3 A g −1 after 10,000 cycles, which can be ascribed to a structural transition from crystalline to amorphous phase during cycling. Meanwhile, the flexible all-solid-state MnO 2 symmetry micro-supercapacitors (MSCs) using sodium alginate bio-hydrogel as electrolyte, the voltage window of the MSCs can be extended to 1.4 V. The MSCs reveals a high areal capacitance of 129.29 mF cm −2 at a current density of 0.2 mA cm −2 . The capacity retention rate up to 94.5% after 4000 cycles, and higher energy density of 35.19 μWh cm −2 at 0.07 mW cm −2 , as well as there is no significant capacitance degradation under different bending states, exhibiting a remarkable electrochemical performance and mechanical flexibility. The crystalline/amorphous ultrathin MnO 2 sheets with high specific surface area were prepared through simple preparation process and found the mechanism of the transformation of MnO 2 from crystalline phase to amorphous phase during the cycle providing a new perspective for the design of high-performance MnO 2 electrodes. • Ultrathin MnO 2 nanosheets are prepared by a simple interfacial reaction of surfactant assistance in water-bath. • The phase structure of ultrathin MnO 2 nanosheets includes crystalline/amorphous states. • The ultrathin MnO 2 nanosheets reveal an ultrahigh specific surface area of 317.56 m 2 g −1 . • The structural transition of ultrathin MnO 2 nanosheets is gradually from crystalline to amorphous phase during cycling. • A flexible micro-supercapacitors based on the ultrathin MnO 2 nanosheets exhibits excellecnt electrochemical performance.

In situ preparation of FeOx nanoparticles embedded N-doped laser-induced graphene for flexible in-plane micro-supercapacitors

In situ preparation of FeOx nanoparticles embedded N-doped laser-induced graphene for flexible in-plane micro-supercapacitors

A Facile and Scalable Fabrication of High-Performance Flexible Laser-Induced-Graphene Micro-Supercapacitors Using Ultrafast Pulse Laser

The rapid growth of wearable and portable electronics has promoted the development of microscale energy storage devices. Among these devices, microsupercapacitors (MSCs) have emerged as promising flexible energy storage devices owing to their high power density, high charge/discharge rate, and long-term cycling stability.[1,2,3] Most synthesis method of graphene electrodes for flexible MSCs rely on complex processes or chemical synthesis routes, such as photolithography, mechanical exfoliation, or chemical and thermal reduction. On the other hand, laser direct writing are a simple, design-flexible, highly scalable, and cost-effective method for graphene production. Here, we developed two types of green flexible microsupercapacitor using femtosecond pulse laser. First, we report a high performance sticker-type flexible microsupercapacitor using highly swollen reduced-graphene oxide electrodes fabricated by an ultrashort pulse laser.[4] Second, we demonstrate the direct fabrication of highly conductive, intrinsically flexible, and green microelectrodes from naturally fallen leaves in ambient air using femtosecond laser pulses without any additional materials.[5] Both types of MSCs not only showed excellent electrochemical performance, but were confirmed to work as a power supply for various applications such as LED and thermometer. Therefore, our flexible microsupercapacitors can be widely applied as energy-storage devices for flexible/wearable electronics.

(Invited, Digital Presentation) 3D Printing of Flexible and Wearable Supercapacitors

Flexible and wearable electronics have recently emerged as a potential solution for next-generation electronics for healthcare, sports, transport, military, soft robotics, artificial intelligence, the internet of things, and other applications. However, these devices are still at a fledgling stage due to the use of traditional manufacturing processes, lack of compatible power supply, poor commercialization capabilities, and integration problems. Here, we present 3D printing approaches for developing batteries and supercapacitors for flexible electronic applications. Such manufacturing techniques can revolutionize the rapidly growing field of flexible and wearable electronics due to their several attributes like; rapid production, simplicity, capability to produce size and shape versatile patterns, computer-aided design, user control, and environmental friendliness.(1-4) Different aspects of 3D printed supercapacitors (such as; device design, ink preparation of electrode/ electrolyte components, rheology control of inks, surface modification to get good print quality, electrochemical performance of printed devices, and flexibility analysis) will be discussed in detail with a focus on future requirements.References Sundriyal P, Bhattacharya S. Scalable micro-fabrication of flexible, solid-state, inexpensive, and high-performance planar micro-supercapacitors through inkjet printing. ACS Applied Energy Materials. 2019;2(3):1876-90.Sundriyal P, Bhattacharya S. Inkjet-printed electrodes on A4 paper substrates for low-cost, disposable, and flexible asymmetric supercapacitors. ACS Applied Materials & Interfaces. 2017;9(44):38507-21.Sundriyal P, Bhattacharya S, editors. 3-D Printed Electrode Materials for Low-Cost, Flexible, and Stretchable Energy Storage Devices. ECS Meeting s; 2019: IOP Publishing.Sundriyal P, Bhattacharya S. Textile-based supercapacitors for flexible and wearable electronic applications. Scientific reports. 2020;10(1):1-15.

Two-Dimensional Titanium Carbides (Ti3C2) Mxene-Based Patterned-Electrodes for High Capacity Micro-Supercapacitors

With the fast growth of wearable & miniaturized electronic devices, internet of things (IoT), and 5G telecommunications, the need for ultrathin, lightweight, and flexible energy storage devices has expanded significantly. Micro-supercapacitors (MSCs) with electrically isolated interdigitated electrodes, have attracted great interest as major power sources for micro-electronic devices, offering high power efficiency, superior rate capability, and excellent cycle durability. MXenes, two-dimensional (2D) metal carbides and nitrides, have been considered as a promising candidate for state-of-the-art energy storage applications, due to their intriguing combinational properties such as excellent electrical conductivity, large surface area, tunable surface chemistry, and pseudo-capacity. 1 In this work, we report titanium carbides (Ti3C2) MXene-based MSCs with sub-micron gap between electrodes exhibiting high areal capacitance and superior rate capability, realized by microfabrication method based on focused ion beam (FIB) and photolithography.2 We also demonstrate a facile and reliable process for scalable manufacturing of on-chip and flexible MSCs for wearable/portable and miniaturized microelectronics. The MXene MSCs fabricated utilizing the cutting-edge nanofabrication technology in an 8-inch wafer have shown an outstanding volumetric capacitance and stable cyclic performances, suggesting the developed manufacturing process can accelerate commercialization of MXene-based energy storage devices as power sources for next-generation wearable and miniaturized microelectronics.3 [References] 1 Energy Environ. Sci. 9 2847 (2016) 2 Nano Energy 81 (2021), 105616 3 Chem. Eng. J., 450, 138456 (2022)