Cyclic Galvanostatic Charge-discharge Research Articles

Pd-Co₃O₄/Acetylene Black Nanocomposite as an Efficient and Robust Bifunctional ORR/OER Electrocatalyst for Rechargeable Zinc-Air Batteries

Developing cost-effective and high-performing bifunctional electrocatalysts is pivotal for advancing rechargeable zinc-air batteries (ZABs). In this study, a Pd-Co₃O₄ loaded on acetylene black (Pd-Co₃O₄/C) electrocatalyst was developed with excellent properties for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) using reduced H₂PdCl₄ to modify Co₃O₄/C. The experimental findings indicate that the Pd-Co₃O₄/C electrocatalyst exhibits a favorable half-wave potential for ORR at 0.91 V, a feasible potential for OER at 1.48 V (measured at 10 mA/cm2), also minor Tafel slopes for both ORR (44.65 mV/dec) and OER (58.41 mV/dec). Additionally, it evidences a power density of 186 mW/cm2 in ZABs and good durability during galvanostatic charge-discharge cycling. The impressive performance of Pd-Co₃O₄/C can be ascribed primarily to the beneficial synergistic effect resulting from the composition of Co₃O₄ and Pd embedded within graphite carbon. This research lays the groundwork for the expansion of additional cost-effective and highly effective electrocatalysts in the coming years.

Constructing Co3O4 Nanowire@NiCo2O4 Nanosheet Hierarchical Array as Electrode Material for High-Performance Supercapacitor

The Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array was constructed on Ni foam using hydrothermal and annealing approaches in turn, from which a NiCo2O4 nanosheet could self-assemble on the Co3O4 nanowire. The structure and morphology of the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array were characterized via XRD, EDS, SEM, and FESEM, respectively. The electrochemical performance of the composite array was measured via a cyclic voltammetry curve, galvanostatic current charge–discharge, charge–discharge cycle, and electrochemical impedance and then compared with the Co3O4 nanowire. The results show that the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array could reach a high value of 2034 F g−1 at a current density of 2.5 A g−1. After 5000 galvanostatic charge–discharge cycles, the specific capacitance of the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array could still maintain 94.7% of the original value. Therefore, the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array would be a desirable electrode material for a high-performance supercapacitor.

NiCo-MOFs derived carbon matrix composites: A promising electrode construction for high-performance supercapacitors

Metal-organic frameworks (MOFs) are great precursors and templates for preparing adsorbents, catalysts and electrodes due to the porous structure and high specific surface area. We report a promising approach to prepare nanocrystalline Co, Ni sulfides (CNS) embedded and N self-doped porous carbon (NPC) matrix composites derived from NiCo-MOFs. The CNS@NPC composite was investigated as electrodes for hybrid supercapacitors (HSCs). The prepared electrode achieved specific capacitance of 2789 F g−1 at 1 A/g, and high capacitance retention of 88.93% after 6000 galvanostatic charge–discharge (GCD) cycles under 10 A/g. The HSC structured with CNS@NPC//AC achieved an energy density of 46.79 Wh kg−1 at power density of 800 W kg−1. Meanwhile, specific capacitance of 131.56 F g−1 at 1 A/g and capacitance retention of 99.17% over 6000 GCD cycles under 3 A/g were obtained. Space confinement by the carbon skeleton effectively prevents the aggregation of the redox active nanocrystalline and improves the durability of the electrode. Meanwhile, the carbon skeleton provides abundant charge transfer channels to enhance the redox reaction. In other words, synergistic effect of the carbon skeleton and the active redox nanocrystalline significantly improves the electrochemical properties of the composite.

Synthesis and performance evaluation of bio-derived and synthetic carbon as lithium-sulfur battery cathode

The next-generation of batteries need be both energy dense and environment friendly. Lithium sulfur batteries (LSBs) satisfy both criteria but their practical implementation is marred by the highly resistive nature of sulfur. Carbon-based cathodes play a vital role in mitigating the issue because their high conductivity allows for effective electron transfer during electrochemical cycling. Synthesis and electrochemical evaluation of carbon-based cathodes from two different sources for LSBs was carried out. Herein, two kinds of carbon, namely bio-derived carbon from coconut shells (CC500) and N-doped carbon (NC) from polyacrylonitrile fibers were synthesized and sulfur was incorporated via the melt diffusion route. The composites are characterized by PXRD and TGA, which determined 80 wt% mass loading of sulfur. The higher intensity of G-band over D-band in Raman spectroscopy indicates greater graphitic character for CC500 compared to NC. SEM images show large macro-pore like tunnels in CC500 while NC appears are irregular chunks. EDAX spectra showed 20 wt% N content in NC while CC500 is largely carbon with some minor surface oxygen. In galvanostatic charge–discharge cycling of coin cells, bare CC500/S shows better specific capacity compared to NC/S samples but the trend flips once a separator modified with 4 mg of graphene oxide (GO) is introduced (indicated as NC/S/GO4 and CC500/S/GO4). This points towards synergy between N-doped carbon and GO layer in retaining the soluble polysulfides in the catholyte region. NC/S/GO4 exhibited better capacity i.e., 1453, 1024, 866, 787, 697 mAh/g versus 1016, 779, 672, 551, 441 mAh/g offered by CC500/S/GO4 when discharged at 50, 100, 200, 300 and 500 mA/g, respectively.

Nitrogen-doped graphene quantum dot embedded polyaniline for the fabrication of high-performance flexible supercapacitor with enhanced cycling stability

This article explains the synthesis of high surface area nitrogen-doped graphene quantum dots embedded polyaniline (PANI) and its effectiveness in fabricating flexible printed supercapacitors. A noticeable change in polyaniline's morphology and specific surface area suggests the successful incorporation of graphene quantum dots into the polymer matrix. The synergistic interaction of polyaniline with graphene quantum dots is evident in its energy storage performance. The fabricated supercapacitor prototype with PVA/HCl gel electrolyte exhibited a very high areal capacitance of 128.01 mF cm−2, with an areal energy density of 11.40 μWh cm−2, and a power density of 640 μW cm−2 at 1.6 mA cm−2 current density. Most importantly, the developed supercapacitor exhibited 76.70% of original capacitance after 5000 galvanostatic charge-discharge cycles, which was found to be far better result than a supercapacitor fabricated with pristine polyaniline. Furthermore, the developed supercapacitor demonstrated excellent mechanical stability, retaining its performance at diverse angles and even after 4000 bending cycles. These characteristics make PANI/N-GQD-based supercapacitors appropriate for wearable devices requiring flexibility, cycling stability, and mechanical toughness.

Superior cycle stability and enhanced pseudocapacitive performance of NiAl-LDH decorated carbon cloth for supercapacitor application

Pseudocapacitors, particularly using layered double hydroxides as cathode material, offers high-power capability and increased energy density, making them popular choices for energy storage devices. This study presents a unique porous structure featuring nickel aluminium layered double hydroxide (NiAl-LDH) deposited onto activated carbon cloth (CC) via a single-step electrochemical process. The NiAl-LDH@CC composite demonstrates exceptional pseudocapacitive capabilities with a specific capacitance of 5893.8 mF cm−2 at a current density of 0.7 mA cm−2 calculated from galvanostatic charge–discharge (GCD) responses. An asymmetric supercapacitor (ASC) is constructed using activated carbon cloth (CC) as anode and NiAl-LDH@CC as cathode. The as-built ASC device, with an operational voltage of 1.6 V, achieves a substantial specific capacitance of 310 mF cm−2 at a current density of 0.2 mA cm−2, along with a high energy density ∼51.67 μWh cm−2 and a power density ∼913.84 μW cm−2. An outstanding cycle stability is also observed with a retention rate of 90 % after 10000 continuous GCD cycles.

Charge storage mechanism and pseudocapacitance performance of NiO and Ce-doped NiO synthesized via modified combustion technique

Supercapacitors, as promising energy storage devices, have gained significant attention due to their ability to deliver high power and efficient charge storage mechanisms. In this work, we report the synthesis and electrochemical characterization of pristine NiO and Ni1-xCexO (x = 0.01, 0.02, 0.03) nanoparticles using a single-step auto ignition combustion method. Preliminary investigations indicate that Ni1-xCexO (x = 0.02) nanoparticles (2 % Ce doping) exhibit superior specific capacitance compared to other compositions. Therefore, we focused on structural, morphological, and vibrational studies on pristine and 2 % Ce-doped NiO. XPS and BET techniques were explored to assess the electronic state and porosity of the samples. Subsequent electrochemical performance evaluations included Cyclic Voltammetry (CV) at various scan rates, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopic (EIS) techniques. From CV at a scan rate of 5 mVs−1, specific capacitance values of 419 Fg-1 and 604 Fg-1 were obtained for pristine and 2 % Ce-doped NiO, respectively. GCD studies revealed a specific capacitance of 381 Fg-1 for 2 % Ce-doped NiO at a current density of 1 Ag-1 and demonstrated capacitance retention of 95.1 % over 3000 GCD cycles for a current density of 4 Ag-1. The symmetric two-electrode supercapacitor cell demonstrates exceptional electrochemical performance, exhibiting a high specific capacitance of 122 Fg-1, an impressive energy density of 8.17 WhKg−1, a power density of 700 WKg-1 at 1 Ag-1, and a remarkable 88 % capacitance retention after 5000 GCD cycles. DFT calculations suggest that Ce doping significantly alters pristine NiO's electronic and structural features due to lattice strain. Our work highlights the enhanced electrochemical performance of 2 % Ce-doped NiO and its potential as a good-quality supercapacitor material.

Reversible storage of tetraethyl ammonium cation in CFx-based cathode

Carbon fluorides (CFx) are considered as the potential cation storage materials in alkali metal-based battery systems because of the high theoretical specific capacity (865 mAh g-1 when x = 1). However, the reversibility of cathode reaction is seriously disturbed by the strong metal-fluorine interactions among the electrode products (e.g., LiF). By contrast, the relatively weak N-F bond makes the CFx-based battery system using quaternary ammonium cation (QAA+) a promising alternate, but the electrode mechanism between CFx and QAA+is little understood yet. In this work, tetraethylammonium cation (TEA+) is employed as the charge carrier using the electrolyte solution of sulfolane (SL) for CFx cathode. The CF0.56 electrode exports 710 mAh g-1 during the initial TEA+-CF reaction, and the electrode product (TEAF) can be decomposed under elevated potential that yields amorphous carbon fluoride and a reversible capacity of ∼300 mAh g-1 can be reached in the subsequent galvanostatic charge-discharge cycles. The TEAF product is non-crystallizable that exists in a sticky form on the surface of electrode, which contributes to an improved electrode structural stability while also leads to an unsatisfactory performance of the amorphous carbon fluoride with large number of superficial active sites. The electrode mechanism and the mechanical property of electrode interface are discussed in depth by in-situ Raman and electrochemical quartz crystal microbalance (EQCM) methods.

Waste Bakelite Board Derived Activated Carbon for Supercapacitor Electrode

The low biodegradability of Bakelite waste raises concerns for the environment as it is typically dumped in landfills. Herein we present regenerated activated carbon (AC) prepared from waste Bakelite board. Preparation of the ACs involves carbonization and KOH activation. Afterwards, the as-made AC were doped with N urea and subsequently pyrolyzed at high temperature. The resulting AC, with and without N-doping have been evaluated in supercapacitor. We demonstrate an N-doped AC that exhibits a specific capacitance (Csp) as high as 203.0 F g−1 at 0.5 A g−1 and retains 93.1% of the Csp after 5000 galvanostatic charge discharge (GCD) cycles at 3 A g−1. We also show that a symmetric supercapacitor exhibits a maximum energy density of 10.3 Wh kg−1 at 250 W kg−1. In general, our work shows a cost-effective approach towards high-performance waste-regenerated ACs.

Wide electrochemical stability window of NaClO4 water-in-salt electrolyte elevates the supercapacitive performance of poly(3,4-ethylenedioxythiophene)

Water-in-salt electrolytes (WiSEs) have emerged as the primary preference in the domain of aqueous-based supercapacitors, thanks to their wide electrochemical stability window (ESW > 1.23 V). Here, we have chemically synthesized a unique lettuce coral-like structure of tosylate doped-poly(3,4-ethylenedioxythiophene) (PEDOT-tos) and tested it for supercapacitor application in a 17 molal (m) NaClO4 WiSE, achieving an ESW of 1.9 V. The energy and power densities (Ed and Pd) of our PEDOT-tos supercapacitor are as high as 14 Wh kg-1 and 7210 W kg-1, respectively, with over 80 % capacitance retention after 10,000 continuous Galvanostatic charge-discharge cycles. The NaClO4 WiSE increases the Ed and Pd of PEDOT by several folds compared to traditional H2SO4 electrolyte. This work encourages the exploration of a suitable combination of a PEDOT-based composite material and WiSE for high-performance supercapacitors.

Ligand-engineered Fe(II)-metallo-supramolecular polymer with benzothiadiazole: Boosting electrochromic energy storage efficiency

The development of intelligent electrochromic energy storage devices that visually display color changes to indicate their charging and discharging status while offering high energy and power densities is gaining interest as a renewable energy solution. Our research engineered a bisterpyridine ligand (BTZ) with a benzothiadiazole spacer and its metallo-supramolecular polymer (Fe-BTZ) via Suzuki coupling and complexation reactions. Spectroscopic, morphological, and structural characterizations revealed nano-rod morphology due to higher aggregation of 1D Fe-BTZ metallo-supramolecular polymer. Quasi-solid-state electrochromic devices with Fe-BTZ as the active layer exhibited significant color changes (matte purple to dirty yellow), an optical contrast of 65.2 % at 567 nm, high coloration efficiency (518.2 cm2/C), quick coloration (0.5 s) and bleaching (1.8 s), and exceptional electrochromic durability compared with commonly used Poly-Fe metallo-supramolecular polymer. Conjugated ridged benzothiadiazole spacers enhanced electron mobility between the Fe-center during electrochemical transitions, increasing coloration efficiency, durability, and electrochromic speed. The Fe-BTZ and Prussian blue (PB)-based quasi-solid-state energy storage device also showed fast response times (1.1 s and 1.9 s), high CE (1077 cm2/C), 6500-cycle durability, high volumetric capacitance (70.1 ± 4 F/cm3) with a specific capacity of 10.96 mAh/g at 0.14 A/g current density and 74 % capacitance retention over 20,000 galvanostatic charge–discharge cycles. The device’s ability to power 18 red LEDs demonstrates its practical applicability.

Probing the performance of Co-precipitated Co3(PO4)2@W3(PO4)4/GO electrodes for supercapacitor application

A critical first step in realizing high-performance supercapacitors is the growth of functional electrodes that are inexpensive, stable, and extremely active. To create a variety of electrodes, we present here an inventive approach to fabricating an ordered microporous Co3(PO4)2@W3(PO4)4/GO composites electrode on a nickel foam (NF) substrate that was first created via co-precipitation techniques for nanoparticles and then drop casting method for fabrication of these electrodes. The Co3(PO4)2@W3(PO4)4/GO composite electrodes show good electrochemical activity in three electrode configurations, thanks to its abundant active sites, and high specific surface area provided by graphene oxide (GO) structured microporous structure that facilitates the charge/mass transfer processes. Additionally, Co3(PO4)2@W3(PO4)4/GO composite electrodes are rightly employed as binder-free electrodes for supercapacitor applications, providing excellent specific capacitances, energy and power densities as well as good electrochemical firmness. The Co3(PO4)2@W3(PO4)4/GO electrode exhibits excellent performance, delivering a high specific capacitance of 1230 F/g from cyclic voltammetry (CV), 1420 F/g from galvanostatic charge-discharge (GCD) and long-term cycling stability of over 74.7 % after 10, 000 complete cycles.

Improving Lithium-Ion Battery Performance: Nano Al2O3 Coatings on High-Mass Loading LiFePO4 Cathodes via Atomic Layer Deposition

Lithium iron phosphate (LiFePO4 or LFP) is a promising cathode material for lithium-ion batteries (LIBs), but side reactions between the electrolyte and the LFP electrode can degrade battery performance. This study introduces an innovative coating strategy, using atomic layer deposition (ALD) to apply a thin (5 nm and 10 nm) Al2O3 layer onto high-mass loading LFP electrodes. Galvanostatic charge–discharge cycling and electrochemical impedance spectroscopy (EIS) were used to assess the electrochemical performance of coated and uncoated LFP electrodes. The results show that Al2O3 coatings enhance the cycling performance at room temperature (RT) and 40 °C by suppressing side reactions and stabilizing the cathode–electrolyte interface (CEI). The coated LFP retained 67% of its capacity after 100 cycles at 1C and RT, compared to 57% for the uncoated sample. Post-mortem analyses, including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), were conducted to investigate the mechanisms behind the improved performance. These analyses reveal that Al2O3 coatings are highly effective in reducing LFP electrode degradation during cycling, demonstrating the potential of ALD Al2O3 coatings to enhance the durability and performance of LFP electrodes in LIBs.

Incorporating Ag into Nd-Succinate MOF: Tunned electrochemical supercapacitor behaviour of Ag modified Nd-Succinate and electrochemical reaction mechanism

The electrode materials must be tailored to achieve higher energy and power densities and thus improve the supercapacitor's performance. This study explores the impact of incorporating Silver (Ag) into a Neodymium-Succinate Metal Organic Framework (Nd-Succinate) on supercapacitor behaviour. Initially, the Nd-Succinate MOF was characterized by structural, morphological, and spectroscopic characterizations. Subsequently, Ag/Nd-Succinate was synthesized and characterized. The electrochemical performance of Ag/Nd-Succinate was evaluated in a 6 M KOH electrolyte; the results indicated a significant enhancement in supercapacitor performance upon incorporating Ag into parent Nd-Succinate. From galvanostatic Charge-Discharge cycles (GCD), the capacitance for Ag/Nd-Succinate was determined to be 1389 F/g, i.e., 42 % higher than that of bare Nd-Succinate which was measured at 978 F/g. at a current density of 1.25 A/g. Ag/Nd-Succinate showcased an 89 % retention value for multiple retention cycles, slightly higher than the retention value obtained (84 %) for Nd-Succinate. The results of electrochemical experiments (Cyclic voltammetry (CV) and Electrochemical Impedance Spectra (EIS)) provided information about the nature of electron transfer and capacitance enhancement upon the introduction of Ag into Nd-Succinate. These findings provide valuable information on modifying MOFs and introducing metal that will help produce high-performance supercapacitor electrodes.

Numerical investigation of ionic transport and overpotential effects in the electrolyte of the lithium-ion battery

ABSTRACT In this study, we numerically investigated the electrochemical performance of a CGR 17,600 lithium-ion battery (LIB), focusing on lithium-ion transport dynamics within the electrolyte. Using a one-dimensional Nernst-Planck model and finite difference method, we simulated ion diffusion and migration during galvanostatic charge-discharge cycles. Our model predicts concentration profiles, overpotentials, and resistances, identifying a maximum safe operating current of 0.8271 A. The analysis reveals that diffusion dominates during discharge, while migration prevails during charging. The study also characterises ohmic resistance of 0.0497 Ω and steady-state resistance of 0.1904 Ω, underscoring their importance in battery efficiency. Additionally, a transference coefficient of 0.4 highlights effective ion transport, critical for optimising LIB design and performance.

Synthesis and electrochemical performance of CeO2/NiS nanocomposite for enhanced asymmetric supercapacitor device applications

A novel CeO2/NiS nanocomposite, combining the advantageous properties of transition metal sulfides (high conductivity) and rare-earth metal oxides (excellent stability), was successfully synthesized using a simple hydrothermal method. This composite leverage synergistic effects to potentially achieve superior electrochemical performance in supercapacitor applications. To evaluate its suitability for supercapacitors, the electrochemical performance of the CeO2/NiS electrode was comprehensively investigated using a series of techniques, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) curves, electrochemical impedance spectroscopy (EIS), and cyclic stability analysis. The results demonstrate that the as-prepared CeO2/NiS electrode exhibits significantly improved supercapacitor performance compared to the bare CeO2 electrode. The CV curves of the CeO2/NiS electrode reveal a high specific capacitance of 825.53 F/g at a low scan rate of 5 mV/s, indicating good charge storage capability. Further insights into the charge storage mechanism were obtained using the Trasatti method. This analysis revealed that the total stored capacitance of the CeO₂/NiS electrode is 1250 F/g, with contributions from both outer surface capacitance (94 F/g) and inner diffusion capacitance (1156 F/g). Notably, the dominant contribution (92.5 %) originates from capacitive processes, highlighting the efficient charge storage at the electrode surface. The CeO2/NiS electrode also demonstrates exceptional rate capability, delivering a specific capacitance (Csp) of 710 F/g at a high current density of 1 A/g. Additionally, it exhibits impressive cycling stability, retaining approximately 96.56 % of its initial capacitance even after undergoing 3000 continuous GCD cycles at a high current density of 10 A/g. These results suggest that the CeO2/NiS composite can maintain its performance during extended charge-discharge cycles, a crucial characteristic for practical supercapacitor applications. Finally, an asymmetric supercapacitor device was fabricated using the CeO2/NiS nanocomposite. This device achieved a specific capacitance of 157 F/g, demonstrating the potential of the CeO2/NiS composite for practical energy storage applications.

Synthesis Method Comparison of N-Doped Carbons for Electrochemical Energy Storage

This study investigates nitrogen-doped carbon synthesis and electrochemical properties as electrode material for energy storage devices, an additional focus of the work is on the electrochemical exfoliation synthesis of nitrogen-doped carbon using various precursors and doping methods. The physical properties of the synthesized sample are characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, and Raman spectroscopy. The electrochemical properties of the N-doped carbons are studied using cyclic voltammetry and galvanostatic charge-discharge cycling. Finally, the work explores the potential application of the N-doped carbons as electrode material for energy storage devices, such as supercapacitors. The results show that N-doped carbons exhibit electrochemical performance superior to that of graphene oxide, with higher electrical capacitance. The results demonstrate the potential of N-doped carbons as high-performance electrode materials for electrochemical energy storage applications. This paper aims to explain the advantages of N-doping in carbon materials more precisely in graphene and the use of these materials in creating electrodes for application in supercapacitors and batteries.

Pulsed laser-modified zinc anode with improved dendrite and corrosion resistance for sustainable high performance zinc ion hybrid supercapacitors

This research explores the development and evaluation of zinc ion hybrid supercapacitors (ZIHSCs) with a focus on the enhanced performance and low corrosion attributes of pulsed laser-modified zinc anodes compared to their non-modified counterparts. These anodes, paired with cathodes crafted from activated carbon derived from jute sticks on graphite foil, were immersed in a 2 M zinc sulfate electrolyte. A pivotal aspect of the study is improving the electrochemical properties and corrosion resistance of zinc anodes achieved through precise pulsed laser modification. Extensive electrochemical testing was conducted to assess the capacitive behavior, energy storage capabilities, and durability of the supercapacitors during prolonged cycling. Hence, using the laser modified anode, we attain remarkable stability in Zn||Zn symmetric cells for 1000 h at high current density of 10 mA cm−2 with a capacity of 1 mAh cm−2, and ZIHSCs achieving specific capicitance up to 287 F/g at a current density of 0.1 A/g, and reaching an energy density of 102 Wh/kg while sustaining a power density of 80 W/kg. After 10,000 galvanostatic charge-discharge cycles, these supercapacitors maintained high capacitance values, underscoring their resilience. Notably, charge transfer resistance reduction, improved ion diffusion and enhanced corrosion resistance contributes to the supercapacitors' longevity and efficiency, which can be attributed to these anodes laser-induced surface alterations. This study highlights the crucial role of pulsed laser-modified zinc anodes in advancing ZIHSCs performance, marking a significant step towards achieving efficient and sustainable energy storage solutions.

Synthesis of reduced graphene oxide (rGO)/polyaniline (PANI) composite electrode for energy storage: Aqueous asymmetric supercapacitor

Composite materials have gained significant interest for energy storage applications due to their possible synergistic effects. This work describes the synthesis of reduced graphene oxide (rGO)/polyaniline (PANI) composite thin films using chemical bath deposition (CBD) method. A field-emission scanning electron microscope revealed that PANI spikes coated on rGO sheets in rGO/PANI composite. The electrochemical studies of a rGO/PANI composite electrode showed a specific capacitance (Cs) of 1130F/g Cs at a scan rate of 5 mV/s in 1 M H2SO4 electrolyte. The combined effect of rGO with PANI, a aqueous asymmetric supercapacitor device (ASC) with configuration of rGO/PANI/H2SO4/WO3 produced 97F/g Cs at a 5 mV/s scan rate and retained 82 % capacitance after 5,000 galvanostatic charge–discharge cycles. The ASC achieved a high specific energy of 23 Wh kg−1 at a specific power of 732 W kg−1. The electrochemical properties of rGO/PANI composite indicate a feasible method for creating asymmetric supercapacitors.

Prussian Blue Anchored on Reduced Graphene Oxide Substrate Achieving High Voltage in Symmetric Supercapacitor.

In this work, iron hexacyanoferrate (FeHCF-Prussian blue) particles have been grown onto a reduced graphene oxide substrate through a pulsed electrodeposition process. Thus, the prepared FeHCF electrode exhibits a specific volumetric capacitance of 88 F cm-3 (specific areal capacitance of 26.6 mF cm-2) and high cycling stability with a capacitance retention of 93.7% over 10,000 galvanostatic charge-discharge cycles in a 1 M KCl electrolyte. Furthermore, two identical FeHCF electrodes were paired up in order to construct a symmetrical supercapacitor, which delivers a wide potential window of 2 V in a 1 M KCl electrolyte and demonstrates a large energy density of 27.5 mWh cm-3 at a high power density of 330 W cm-3.