Solid-state Symmetric Supercapacitor Research Articles

Fabrication of aqueous solid-state symmetric supercapacitors based on self-healable poly (acrylamide)/PEDOT:PSS composite hydrogel electrolytes

The composite hydrogel electrolytes developed from conducting polymers own superb/excellent conductive, self-healing, and mechanical properties. However, it is still challenging to exploit them in energy storage devices. To address this issue, novel poly(acrylamide)/poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) composite hydrogel electrolytes were developed through free radical polymerization in which sodium montmorillonite clay was added as a physical crosslinker. The different amounts of PEDOT:PSS were added to the composite hydrogel electrolytes. The structure of the synthesized composite hydrogel electrolytes was investigated by X-ray diffraction (XRD) analysis. The surface morphology of the composite hydrogel electrolyte was examined with the field emission scanning electron microscopy (FESEM) and elemental composition was determined using energy-dispersive X-ray spectroscopy (EDX). The ionic conductivity was measured at ambient temperature. Among the synthesized electrolytes, PEDOTAAM34 achieved the highest ionic conductivity of 13.7 × 10−3 S/cm at room temperature. Furthermore, electrochemical studies were performed by sandwiching the composite hydrogel electrolytes between symmetric carbon-coated graphite electrodes. The fabricated AC/PEDOTAAM34/AC based symmetric supercapacitor attained the highest specific capacitance of 327 F/g at 3 mV/s and 385.4 F/g (energy density of 53.57 Wh/kg at a power density of 100.08 W/kg) at 100 mA/g current density. The self-healable characteristics of symmetric supercapacitors were confirmed by powering up a light-emitting diode (LED).

Coconut Shell-Derived Activated Carbon for High-Performance Solid-State Supercapacitors

Coconut shells, low-cost and renewable agro-wastes, were used as a starting material in the synthesis of hierarchical activated carbons via hydrothermal, KOH-activation, and carbonization techniques. The ratio of KOH to hydrochar was varied in a systemic manner to study how it influences the texture and electrochemical behavior of the capacitor. Coconut shell-based carbon coated on nickel foams presented a surface area of 1567 m2 g−1, with micropores as well as mesopores widely distributed. The sample showed superior electrochemical performance, attaining 449 F g−1 at 1 A g−1 in 6 M LiNO3 aqueous solution. The solid-state symmetric supercapacitor device delivered a specific capacitance of 88 F g−1 at 1 A g−1 and a high energy density of 48.9 Whkg−1 at a power density of 1 kW kg−1. At a wide voltage window of 2.0 V, the sample was highly stable during the cycle test, showing a 92% capacitance retention at 2 A g−1 after cycling for 5000 times. The superior performance is due to the sample possessing great BET surface area, a good distribution of pores, and the usage of a suitable electrolyte. This facilitates an electrical double layer that can be deployed for applications to store energy.

Facile fabrication of hierarchically porous graphene/poly(1,5-diaminoanthraquinone) nanocomposite fibers as flexible and robust free-standing electrodes for solid-state supercapacitors

BackgroundFiber-shaped supercapacitors have attracted more and more interests for portable/wearable electronics. However, the practical application is suffering from their tedious fabrication and limited electrochemical performance. MethodsHere, hierarchically porous graphene/poly(1,5-diaminoanthraquinone) nanocomposite (ErGO/PDAA) fibers were fabricated as flexible and robust free-standing electrodes for supercapacitors, via facile coagulation of expanded graphene oxide (EGO) and PDAA nanomaterials with different morphologies, such as nanoparticles (PNPs), nanotubes (PNTs), and nanoribbons (PNRs), in CaCl2 bath, followed by reduction with hydroiodic acid (HI). Significant findingsAll the three ErGO/PDAA fibers showed distinctly enhanced electrochemical property than the ErGO fiber. Furthermore, with the same feeding ratio of EGO and PDAA (6:4), the ErGO/PNTs fiber possessed better electrochemical capacitive property than the other two, ErGO/PNPs and ErGO/PNRs fibers, owing to the unique hierarchical pores. The solid-state symmetric supercapacitor (SSC) possessed specific capacitance, energy and power densities of 35.0 mF cm−1, 3.11 mWh cm−1, and 61.4 mW cm−1, respectively, and retained 83.3% of its initial capacitance after 5000 cycles.

Engineering Architecture of 3D-Urchin-like Structure and 2D-Nanosheets of Bi2S3@g-C3N4 as the Electrode Material for a Solid-State Symmetric Supercapacitor

Engineering Architecture of 3D-Urchin-like Structure and 2D-Nanosheets of Bi₂S₃@g-C₃N₄ as the Electrode Material for a Solid-State Symmetric Supercapacitor

Influence of acidic type on nanostructures and electrochemical performance of polyaniline for flexible supercapacitors and improved performance based on 3D honeycomb-like nanosheet by doping HPF6 acid

Designing and preparing polyaniline (PANI)-based flexible electrode materials with special nanostructure hold critical promise as capacitive materials. Here, the PANIs were synthesized in HCl, H2SO4, phytic acid and HPF6 reaction systems with the same concentration via fast microwave-assisted chemical polymerization. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-vis absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS) were conducted to characterize their nanostructures and chemical compositions. Results reveal an apparent influence of acidic types on PANI morphology and nanostructures. The HPF6-doped PANI/carbon cloth (F-PANI/CC) show the morphology of 3D honeycomb-like nanosheets and highly ordered phenazine-like oligomeric structure as well as higher homogeneous protonation of PANI backbones on the substrate of carbon cloth (CC). These main features favor the formation of rich electron centers, density of electric charges, and better contact and reaction between PANI materials and electrolyte. As a consequence, the assembled F-PANI/CC-based symmetric solid-state supercapacitor exhibits favorable electrochemical performance with a maximum energy density of 32.6 Wh kg−1 and a maximum power density of 1693 W kg−1 at a voltage window of 1.0 V compared with other PANI electrode materials. This work would inspire the HPF6-doped PANI electrode materials for high-performance flexible supercapacitors.

Chiral Nematic Cellulose Nanocrystal/Germania and Carbon/Germania Composite Aerogels as Supercapacitor Materials

The development of novel aerogel materials with chiral nematic ordered structures offers exciting pathways for the fabrication of multifunctional hybrid materials with enhanced functionality. Aerogels prepared from cellulose nanocrystals are especially interesting due to their unique structural properties. To promote applicability in energy storage materials, it is often necessary to incorporate metals and metal oxides into three-dimensional porous nanostructures. In this study, germania was incorporated into a chiral nematic cellulose nanocrystal aerogel using a sol–gel method. Interestingly, our approach does not disturb the order of the original chiral nematic CNC aerogels, providing hybrid aerogels with a large concentration of randomly distributed GeO2 nanoparticles and specific surface areas up to 705 m2 g–1. Carbonization of the composite material afforded a highly ordered material with no collapse during compression and good shape recovery after release. The combination of the electrochemical double layer capacitance provided by the carbonaceous skeleton and the pseudocapacitive contribution from the GeO2 nanoparticles resulted in materials with a maximum Cp of 113 F g–1 that exhibited good capacitance retention. To push the boundaries of safer energy storage devices based on renewable resources, we demonstrate the preparation of an all-cellulose solid-state symmetric supercapacitor.

Three-dimensional nanobranched TiO2-carbon nanotube for high performance supercapacitors

Developing high capacity solid-state super capacitors and exploring their storage mechanism is one of the ongoing scientific topics. Here a novel TiO2-carbon nanotube (CNT) electrode is prepared by electrochemical deposition of TiO2 nanostructures on the CNT film. In situ Raman spectroscopy showed that the ion transfer kinetics of 3D rutile-based TiO2 were mainly controlled by ion adsorption. Symmetric solid-state supercapacitors compose of two TiO2-CNT electrodes and H2SO4-polyvinyl alcohol gel electrolyte. The devices show a high energy density of 82.5 Wh kg−1 and specific capacitance of 345.7F g−1 at 1.0 A g−1. Furthermore, the TiO2-CNT supercapacitor illustrates excellent cyclic stability with capacitor retention of 93.3% after 10,000 cycles, and a low leakage current of 9 μA after 2 h. This may due to the matching of the diffusion path topology of the rutile-doped less anatase structure. These results demonstrate that the TiO2-CNT supercapacitor may bring new opportunities to the power supply of portable electronics in the future.

Enhanced specific energy of silver-doped MnO2/graphene oxide electrodes as facile fabrication symmetric supercapacitor device

The present work is about the preparation of silver (Ag)-doped manganese oxide (MnO2)/graphene oxide (GO) composite thin films are deposited by a facile and binder-free successive ionic layer adsorption and reaction (SILAR) method for the first time. The Brunauer-Emmett-Teller (BET) study revealed the nanosheets of MnO2–Ag3/GO exhibit high specific surface area of 192 m2 g−1. The tailored flower-like morphology and interconnected nanosheets of MnO2–Ag3/GO electrodes achieved high electrochemical performance. The maximum specific capacitance (Cs) of 877 F g−1 at the scan rate of 5 mV s−1 is obtained for MnO2–Ag3/GO electrode tested in 1 M sodium sulfate (Na2SO4) electrolyte with capacity retention of 94.57% after 5000 cycling stability. The MnO2–Ag3/GO composite-based flexible solid state symmetric supercapacitor (FSS-SSC) device delivered Cs as 164 F g−1 with specific energy of 57 Wh kg−1 at specific power of 1.6 kW kg−1 and capacitive retention of 94% after 10,000 cycles.

Biowaste derived porous carbon sponge for high performance supercapacitors

Here, an agricultural waste (the stem pith of helianthus annuus, SPHA) is firstly used as the precursor for preparing three-dimensional (3D) porous carbon sponge (PCS). The as-prepared 3D PCS (SPHA-700) possesses unique sponge-like structure, large specific surface area (SSA) and high nitrogen doping level (4.52 at.%), which benefit the enhancement of conductivity (5.8 S cm−1) and wettability. As a binder-free electrode for solid-state symmetric supercapacitor, SPHA-700 delivers a relatively high specific capacitance of 137.1 F g−1 at 0.5 A g−1. Moreover, activated SPHA-700 (SPHA-ac-700–2) displays an even higher specific capacitance (403.6 F g−1 at 0.5 A g−1) in 6.0 M KOH electrolyte. The SPHA-ac-700–2-based symmetrical supercapacitor can offer high specific capacitance (271 F g−1 at 1 A g−1) and good rate capability (82.1% of capacitance retention at 1–80 A g−1) in 6.0 M KOH electrolyte, together with high energy density (23.3 Wh kg−1 at 450 W kg−1) in 1.0 M Na2SO4 electrolyte. Such excellent performance of SPHA-ac-700–2 is believed to have originated from the crushed sponge-like structure, O/N-co-doping (10.6 at.% O and 3.3 at.% N), high SSA, large total pore volume, and hierarchical pore structure.

Solid-State Electrochemical Energy Storage Based on Soluble Melanin

Biocompatible and biodegradable powering materials are appealing systems for biomedical and electronic devices. Melanin is a natural and multifunctional material with redox capability, which is of great interest in electrochemical energy storage functionalities. In our work, we explored the use of soluble melanin derivatives as active materials for symmetric solid-state supercapacitors operating in the dark and under illumination. We observed that our devices were photo-pseudocapacitive. Additionally, under illumination, our best device showed a specific capacitance of 57.7 mFg−1 at a scan rate of 0.01 Vs−1, with a decrease of 53% in resistance compared to that in the dark. Our outcome suggests that soluble melanin is a promising material for solid-state powering elements in wearable and environmentally friendly devices.

Self-activated ‘green’ carbon nanoparticles for symmetric solid-state supercapacitors

Tuning of porosity and surface properties of nanoparticles especially on carbon-based nanomaterials, adopting a ‘greener’ or self-activation synthesis technique for electrical charge storage, is progressing. Herein, we report the self-activation of Teak wood sawdust in a nitrogen atmosphere at different activation temperatures to synthesize carbon nanoparticles. The activated carbon nanoparticles synthesized at 900 °C exhibits a maximum ~ 360 m2 g−1 surface area with ~ 2 nm average pore size diameter. Five electrolytes viz. KOH, KCl, Na2SO4, NaCl, and H3PO4 are used for studying the supercapacitance nature of the activated carbon nanoparticles in a 3-electrode configuration. A maximum specific capacitance of ~ 208 F g−1 @ 0.25 A g−1 is obtained in 1 M KOH as the electrolyte. Two symmetric supercapacitors, aqueous (1 M KOH) and solid-state (PVA/KOH), are fabricated, and their performance difference is compiled. The solid-state symmetric supercapacitor performs in a wider voltage window (1.7 V) with a superior energy density of 27.1 Wh kg−1 at a power density of 178 W kg−1.

A novel strategy to achieve 2V symmetric supercapacitor using B, N doped rGO as an electrode material in “water in salt based hydrous electrolyte”

Design of solid-state symmetric supercapacitors (SSCs) with superior power density, energy density and long cycle life using carbonaceous electrode materials in aqueous electrolyte media remains a great challenge. A high working potential window of SSC-based on aqueous electrolyte can be achieved by “trapping” free water molecules. Herein, the Lewis acid/base characteristic of B & N-doped reduced graphene oxide was synthesized through hydrothermal process and utilized for solid-state SSC fabrication. A solid-state electrolyte composed of polyethylene glycol (PEG) as water trapping agent and sodium dodecyl sulfate as ionic conductivity improving agent are used for solid-state SSC fabrication. The ethylene oxide unit of PEG polymer chains tightly binds the free water molecules and provides thermodynamic stability. This hydrous electrolyte offers ~2 V electrochemical potential windows to the SSC device which is greater than the normal aqueous electrolyte. The SSC device based on hydrous electrolyte showed maximum ~10.58 kW kg−1 power density and ~43.33 W h kg−1 energy density. In addition, the superior life cycle of ~97.85% specific capacitance retention was obtained after 10,000 continuous charge/discharge cycles at 5 A g−1 current density.

Time-intended effect on electrochemical performance of hydrothermally reduced graphene oxide nanosheets: Design and study of solid-state symmetric supercapacitor

Self-organized porous sheet-like assemblies have attracted extensive attention for the development of flexible high-performance electrodes. This work demonstrates the facile synthesis and effects of reduction time on the electrochemical performance of porous sheet-like assemblies of reduced graphene oxide (rGO) on carbon cloth. An rGO porous assembly with a reduction time of 4 h exhibited a superior specific capacitance of 456 F/g at a scan rate of 5 mV/s and 223 F/g at a current density of 1 mA/cm2, with ~ 93.9% initial capacity retention over 2000 cycles. A solid-state symmetric supercapacitor device constructed of a rGO4//rGO4 porous assembly achieved a specific capacitance of 45.86 F/g at a scan rate of 5 mV/s and yielded an energy density of 1.27 Wh/kg and specific power of 833.3 W/kg in a PVA-H2SO4 gel polymer electrolyte. Furthermore, the flexible solid-state symmetric device provides outstanding cyclic stability with a 95.3% retention of its initial capacity over 2000 cycles. Thus, electrodes constructed of rGO porous sheets show great potential for flexible and transparent solid-state symmetric energy storage devices.

SILAR synthesized nanostructured ytterbium sulfide thin film electrodes for symmetric supercapacitors

A simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method was used for synthesis of ytterbium sulfide (Yb2S3) thin film. The valence states and crystal structure of Yb2S3 thin film material were identified using X-ray photoelectron spectroscopy and X-ray diffraction analysis, respectively. Wettability test of Yb2S3 thin film showed hydrophilic nature with the value of 21.70°. The surface texture of Yb2S3 thin film was examined using field emission scanning electron microscope (FE-SEM). The specific surface area and pore size distribution were measured using the Brunarer-Emmet-Teller (BET) and Barrette-Joynere-Halendar (BJH) methods. The supercapacitive performance of Yb2S3 thin film was studied using cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance tests in 1.0 M Na2SO4 aqueous solution. The Yb2S3 electrode showed specific capacitance (Cs) of 181 F g−1 with 83% capacity retention up to 3000 CV cycles. The aqueous symmetric supercapacitor (ASSc) device with the configuration of Yb2S3/Na2SO4/Yb2S3 and solid-state symmetric supercapacitor (SSSSc) device of configuration of Yb2S3/PVA-Na2SO4/Yb2S3 were fabricated. The ASSc device showed better supercapacitor performance (energy density (E.D.) of 8.25 Wh kg−1 at power density (P.D.) of 0.56 kW kg−1) than the SSSSc device.

Kraft lignin-derived free-standing carbon nanofibers mat for high-performance all-solid-state supercapacitor

In the present investigation, renewable kraft lignin-based nanofibers were synthesized by facile electrospinning technique and further converted into carbon nanofibers (CNFs) by heat treatment at different temperatures (600, 800 and 1000 °C). These different heat treated carbon nanofiber mats were characterized using SEM, Raman, FTIR, BET and electrochemical workstation. These CNFs were used as a free-standing electrode and characterized for electrochemical performance using a three-electrode system. Among different electrodes, the 800 °C heat treated CNF electrode shows higher specific capacitance (196.63 F/g @ 1 A/g) as compared to the 600 and 1000 °C heat treated CNF electrodes. Based on the electrochemical performance, 800 °C heat treated CNF electrode is selected to assemble two different types of symmetrical supercapacitor devices i.e., aqueous (using 1 M H2SO4) and solid-state electrolyte using PVA-1M H2SO4 polymer gel. The solid-state electrolyte device operating potential window of 0–2 V which is higher than that of an aqueous electrolyte based device. In addition to this, it delivers higher energy and power density as 62.6 Wh/kg and 1.25 kW/kg respectively with an efficiency of 99.5% after 10,000 cycles. These remarkable results of Kraft lignin-derived ribbon type CNF based solid-state symmetrical supercapacitor device opens new paths for the development of futuristic carbon-based free-standing mat as energy storage devices.

High performance solid state symmetric supercapacitor based on reindeer moss-like structured Al(OH)3/MnO2/FeOOH composite electrode for energy storage applications

Developing an efficient, clean, sustainable, and reliable energy storage system is still a key challenge to resolve the growing demands of energy consumption. In this regard, supercapacitor becomes one of the foremost promising and emerging types of energy storage systems comprising properties of traditional batteries and conventional capacitors. Herein, a binder-free composite electrode of Al(OH)3/MnO2/FeOOH (AMFO) has been synthesized on stainless steel substrate via a facile, eco-friendly, and cost-effective Layer by Layer method at room temperature. The high resolution scaning electron microscopy reveals the mesoporous reindeer moss-like morphology of the synthesized electrode. The supercapacitive behaviour of the synthesized electrode has been explored in 1 M Na2SO4 electrolyte solution by using electrochemical measurement. The highest specific capacity of 2557 C g−1 has been obtained at a scan rate of 5 mV s−1 having wide potential range (−1.10 to 1.05 V). Further, a symmetric prototype supercapacitive device has been fabricated by coupling the AMFO electrodes. The high specific capacitance of 511 F g−1 has been obtained with ultra-high energy and power densities of ∼443 Wh kg−1 and ∼13 kW kg−1, respectively. These results indicate that this electrode has potential practical applications as a power backup, portable electronic device, and energy storage system.

Nanofiller-assisted Na+-conducting polymer nanocomposite for ultracapacitor: structural, dielectric and electrochemical properties

We report the preparation of ZrO2 nanofiller-incorporated polymer nanocomposite electrolyte based on the PEO-NaPF6 matrix via standard solution cast method. The structure and morphology of polymeric films have been examined with X-ray diffraction and field emission scanning electron microscopy. Different interactions between the polymer, salt and nanofiller have been examined by Fourier transform infrared technique. The temperature-dependent (40–100 °C) electrical conductivity has been examined from complex impedance spectroscopy (CIS). The highest ionic conductivity is exhibited by 5 wt% nanofiller-based electrolyte and recorded ~ 2 × 10–4 S cm−1 at 100 °C. The voltage stability window of polymeric film checked from linear sweep voltammetry is about ~ 4 V, and ion transference number close to unity confirms the major contribution from ion conduction. The dielectric properties have been explored in terms of complex permittivity, loss tangent and complex conductivity. The dielectric plots have been further fitted with an associated equation to evaluate principal dielectric parameters. The optimized polymer electrolyte possesses the lowest relaxation time and the highest dielectric constant that suggests the highest ionic conductivity, which is in good correlation with impedance results. The dc conductivity is also highest for the optimum system, and relaxation time decreases with an increase in temperature. The thermal stability of polymer electrolytes is about 200 °C, as examined by thermogravimetric analysis (TGA). The ion transport parameters n, μ, D have been evaluated via FTIR, impedance spectroscopy and Bandara and Mellander (B–M) approach. Finally, the optimized polymer nanocomposite film has been used as an electrolyte-cum-separator for the fabrication of a solid-state symmetric supercapacitor. The electrochemical parameters specific capacitance, energy density, power density have been examined from cyclic voltammetry and galvanostatic charge–discharge technique. It may be concluded that nanofiller incorporation is an effective strategy to enhance the properties of electrolyte and has the potential to adopt as an electrolyte-cum-separator for ultracapacitor.

Lignocellulose based Bio-waste Materials derived Activated Porous Carbon as Superior Electrode Materials for High-Performance Supercapacitor

• Synthesis of activated porous carbon from bio waste. • Symmetric super capacitor based on the activated porous carbon attributes excellent electrochemical performance. • The symmetric super capacitor device and the carbon itself evinced excellent long cycle stability and high cell voltage. • High specific energy and specific power are realized in super capacitor analysis. • The system potential is calculated by utilizing the upper limit of the capacitive potential value. Rechargeable energy storage systems are highly demandable in the present scenario. Willing to engineer economical energy storage applications using environmentally sustainable technology, a high-temperature controlled heating process has synthesized activated porous carbon in an inert atmosphere with the bio-waste materials' KOH activation process. X-ray diffraction analysis confirms the phase and field emission scanning electron microscopy characterize the morphological features. Electrochemical studies are evaluated in envisaging the prospective approach of that system in the energy storage devices. This activated porous carbon has a mean pore size of 1.81 nm and a specific area of 811.8 m 2 g −1, which is high. The specific capacitance is evaluated to be 565.2 Fg −1 . The porous carbon exhibits 98% stability up to 10000 cycles with high specific energy of 21 Whkg −1 at the specific power of 5000 Wkg −1 . Assembled solid-state symmetric supercapacitor depicts 96% capacity retention with a high specific energy of 24.5 Whkg −1 at the specific power of 801.82 Wkg −1 . The large surface area with porosity that enhanced the amount of charge storage can boost an electrical double-layer capacitor. The high value of specific capacitance and long cycle stability makes it a prospective candidate to attain the urge for the establishment of new functional materials for energy storage.

Combined electrochemical and DFT investigations of iron selenide: a mechanically bendable solid-state symmetric supercapacitor

Graphene analogous nanoflakes morphology of iron selenide for advanced flexible solid-state symmetric supercapacitor.

The role of uniformly distributed ZnO nanoparticles on cellulose nanofibers in flexible solid state symmetric supercapacitors

Paper—a flexible, foldable, and cost-effective substrate made of one-dimensional cellulose nanofibers (1D-CNF)—is being extensively investigated as a promising aspirant for wearable as well as foldable energy storage appliances.