Performance Supercapacitors Research Articles

High-temperature anodization route to nanoporous niobium oxides with enhanced supercapacitive properties in aqueous electrolytes

Relatively little work has been done on Nb2O5 pseudocapacitive behaviors in aqueous solutions. Here, the galvanostatic anodization of niobium in K2HPO4-containing glycerol electrolyte at high temperature is fully explored. The anodically grown films on niobium have ordered nanoporous morphology and are composed of a low-crystalline orthorhombic Nb2O5, which can be directly employed as supercapacitor electrodes without any posttreatment process. To further improve their supercapacitive performances, a facile technique to generate Fe-doped Nb2O5 films is developed, where the as-anodized films are treated by an electrochemical doping in FeCl3 ethylene glycol solution. The Fe-doped Nb2O5 films show a wider potential window and higher capacitance than that of the as-anodized films in aqueous electrolytes. They present a maximum areal capacitance of 168.1 mF cm−2 at 1 mV s−1 and excellent cycling stability with 85.8 % capacitance retention after 10,000 cycles. The charge storage in the Fe-doped Nb2O5 is believed to occur by the incorporation of Li+ ions with concomitant reduction of Nb5+ to Nb4+ in aqueous lithium-containing solutions. Unlike nonaqueous media, Li+ intercalation/deintercalation in aqueous media is a diffusion-controlled process, leading to the comparatively slower pseudocapacitive processes. Nevertheless, in terms of an industrial applicability the Fe-doped Nb2O5 films deserve special attention.

Effects of Crumpling Stage and Porosity of Graphene Electrode on the Performance of Electrochemical Supercapacitor.

The performance characteristics of supercapacitors composed of crumpled graphene electrodes and aqueous NaCl electrolytes are investigated through Molecular Dynamics (MD) simulations using a newly developed crumpled graphene-based supercapacitor model. Results suggest that the three-dimensional configuration of crumpled graphene boosts electrolyte-electrode interaction. This improved interaction, which includes a larger ion-accessible zone, increases the specific capacitance of the supercapacitor by roughly 400% (16.4 μF/cm2) compared to planar graphene electrodes. Examining the effect of different stages of crumpling and the inclusion of pores on the electrode surface shows that the stages of crumpling substantially influence the supercapacitor performance. A smaller crumpling radius, meaning fully crumpled stage, improves the performance as increased crumpling leads to better packing efficiency, which aids in more ion separation. Furthermore, adding pores on the surface of crumpled graphene improves the ion accessibility by creating additional adsorption sites. An exceptional capacitance of 19.8 μF/cm2 is obtained for a porosity of 20%. However, the results suggest that the in-plane-porosity of the electrode needs to be optimized as there is a decline in specific capacitance after that point (20% porosity), indicating a suboptimal relationship between the charge distribution, specific surface area (SSA) and the porosity of the electrode.

Potential difference-induced electrodeposition of defect-rich α-cobalt hydroxide on porous copper (PCu): High-voltage performance of supercapacitor

Designing electrode materials for aqueous battery-type supercapacitors to extend the operating voltage window remains a significant challenge to increase the energy density of aqueous supercapacitors. In this work, a directional electrodeposition method without any additives was employed to deposit α-Co(OH)2 onto a porous copper (PCu) current collector substrate, which involves the fabrication of a supercapacitor electrode material with a cross-linked network structure named α-Co(OH)2@PCu900. The potential difference between copper and cobalt facilitated the formation of a larger interlayer spacing for α-Co(OH)2. In addition, crystals of α-Co(OH)2 with different orientations exert stress on one another, leading to lattice distortion and vacancy formation. The morphology and microstructure of materials were analyzed through techniques such as SEM, HRTEM, XRD, and XPS, confirming the validity of the experimental design. This defect-rich, large interlayer spacing structure facilitates ion intercalation and deintercalation during the charge-discharge process, thereby expanding the operating voltage window. In a three-electrode system, α-Co(OH)2@PCu900 exhibited a potential range from −0.45 V to 0.55 V and demonstrated an areal capacitance of 2580 mF cm−2 and specific capacitance of 600 A g−1 at 2 mA cm−2. The α-Co(OH)2@PCu900 was used as the cathode material and commercial reduced graphene oxide (rGO) was used as the anode material in an asymmetric supercapacitor, and the ASC device exhibited an areal capacitance of 295.3 mF cm−2 and a specific capacitance of 87.89 F g−1. Notably, it retained a high energy density of 0.12 mW h cm−2 (35.27 Wh kg−1) at a power density of 1.7 mW cm−2 (505.95 W kg−1). This method established α-Co(OH)2@PCu900 as a promising supercapacitor electrode material, providing a viable strategy for designing and fabricating functional electrode materials.

Constructing hollow cobalt sulfide nanocages strung by manganese molybdate nanorods for high-efficiency supercapacitors and electrocatalytic methanol oxidation

Constructing core-shell heterostuctures with rationally designed nanoarchitectures and components is a promising strategy to pursuit high-efficiency energy storage and conversion in supercapacitors (SCs) and direct methanol fuel cells (DMFCs). Herein, a multi-dimensional MnMoO4@CoS core-shell heterostructure is designed and synthesized by stringing metal-organic framework-derived hollow CoS nanocages with MnMoO4 nanorods. Such heterostructure provides more electroactive sites and enhanced structural stability. Theory calculations unveil that the work function difference between MnMoO4 and CoS induces the charge redistribution and modulate interfacial electronic configuration in the MnMoO4/CoS heterojunction. Meanwhile, a interfacial built-in electrical field is established, enhancing interfacial charge transfer efficiency and promoting the surface adsorption of electrolyte ions. By integrating all these advantages, the MnMoO4@CoS electrode demonstrates enhanced rate capacities (933 C g−1 at 1 A g−1 and 623 C g−1 at 10 A g−1) and cycling durability (90.3 % capacity retention after 10,000 cycles) compared to bare MnMoO4 and CoS electrodes. Moreover, the MnMoO4@CoS electrode exhibits an appreciable electrocatalytic performance for methanol oxidation, with a current density of 294.8 mA cm−2 at 10 mV s−1 and 96.6 % current retention after 10,000 s. Our work offers a fundamental guideline for designing and engineering core-shell heterostructures with desirable electrochemical performance for SCs and DMFCs.

Optimizing Energy Solutions: Mott-Schottky Engineered 1D/3D CoWO4(OH)2·H2O/MoS2 Heterostructure for Advanced Energy Storage and Conversion Application.

Heterostructure engineering offers a powerful approach to creating innovative electrocatalysts. By combining different materials, it can achieve synergistic effects that enhance both charge storage and electrocatalytic activity. In this work, it is capitalized on this concept by designing a 1D/3D CoWO4(OH)2·H2O/molybdenum disulfide (CTH/MoS2) heterostructure. It is achieved this by in situ depositing 3D MoS2 nanoflowers on 1D CTH nanorods. To explore the impact of precursor choice, various sulfur (S) sources is investigated. Interestingly, the S precursor influenced the dimensionality of the MoS2 component. For example, L-cysteine (L-cys), and glutathione (GSH) resulted in 0D morphologies, thiourea (TU) led to a 2D structure, and thioacetamide (TAA) yielded a desirable 3D architecture. Notably, the 1D/3D CTH/MoS2-TAA heterostructure exhibited exceptional performance in both supercapacitors (SCs) and quantum dot-sensitized solar cells (QDSSCs). This achievement can be attributed to several factors: the synergetic effect between 1D CTH and 3D MoS2, improved accessibility due to the multi-dimensional structure, and a tailored electronic structure facilitated by the Mott-Schottky (M-S) interaction arising from the different material Fermi levels. This interaction further enhances conductivity, ultimately leading to the observed high specific capacity in SCs (154.44mAhg-1 at 3mAcm-2) and remarkable photovoltaic efficiency in QDSSCs (6.48%).

Tailoring novel glycerol-potassium iodide deep eutectic solvents: A comprehensive investigation of physical, structural, and electrochemical properties

A novel Deep Eutectic Solvent (DES) can be formed between glycerol (Gly) and potassium iodide (KI). This study presents a comprehensive physicochemical characterization of these designed DES. The DES compositions, DES-Gly-KI and DES-Gly-KI-EtOH, consist of a hydrogen bond donor (Gly), a hydrogen bond acceptor (KI), and a viscosity-reducing solvent (ethanol (EtOH)). Experimental methodologies, including UV–VIS spectroscopy, mass spectrometry, Fourier transform infrared spectroscopy, and rheological studies such as density and viscosity, are employed to elucidate molecular interactions and structural characteristics. Karl Fischer titration is also conducted to analyze the moisture content in this prepared DES systems. The electrochemical performance of supercapacitors is also analyzed using cyclic voltammetry and electrochemical impedance spectroscopy. The specific capacitance values are found to be 10.32 F/g and 19.18 F/g for DES-Gly-KI and DES-Gly-KI-EtOH-5, respectively. The findings contribute in understanding DES behaviour, reveal distinctive physicochemical attributes, offering valuable insights into crafting and optimizing novel DESs, which is customized to meet distinct industrial requirements.

Harnessing NaNH2 as a dual-function activator for synthesis of porous carbon and its impact on enhanced supercapacitor performance: a review

Harnessing NaNH2 as a dual-function activator for synthesis of porous carbon and its impact on enhanced supercapacitor performance: a review

Construction of Moiré-like TiO2/polypyrrole electrodes for high performance photo-assisted supercapacitors

There is currently a need for research into using external energy to increase the performance of the supercapacitor in energy storage systems because of their poor energy density. This paper reports the effective creation of photo-assisted supercapacitors with moiré-like morphology using polypyrrole (PPy) and titanium dioxide nano powder to replicate the surface of inexpensive and widely available CD discs. The composite material combines the moiré-like superstructure's strong light trapping property with titanium dioxide's high photo-sensitivity, achieving the aims of boosting light absorption, extending the optical route, and improving capacitor performance under light. By combining morphology construction and external energy interventions to improve capacitor performance, the specific capacitance under light is 509.0 F g−1 at 1 A g−1, 13.1 % higher than the same material without moiré-like morphology (449.9 F g−1). When assemble into a sandwich-structured symmetric supercapacitor, it has an area specific capacitance of 99.42 mF cm−2 and an energy density of 7.28 Wh kg−1 at a power density of 217.4 W kg−1, outperforming typical photo-assisted supercapacitors. The current work suggests a practical and straightforward method for increasing the light absorption efficiency and performance of photo-assisted supercapacitors.

Flexible screen-printed supercapacitors with asymmetric PANI/CDC–AC electrodes and aqueous electrolyte

Abstract We report the fabrication and electrical performance of screen-printed flexible supercapacitors based on activated carbon (AC) and polyaniline (PANI)/carbide-derived carbon (CDC) composite electrodes, and neutral aqueous electrolytes. The devices are entirely constructed from safe, low-cost, and non-toxic materials, fabricated through a mass production capable screen printing process, and fully disposable with normal household waste. Symmetric and asymmetric cells with a thin planar face-to-face structure were fabricated on polyethylene terephthalate (PET) substrate, using eco-friendly chitosan binder based electrode inks, and printed graphite current collectors. The asymmetric cell configuration, with a PANI/CDC positive electrode and an AC negative electrode, demonstrated significantly improved electrochemical performance, through increased operating voltage, energy density and power density, improved cyclic stability and rate capability, and decreased equivalent series resistance (ESR) and leakage current, compared to previously reported symmetric PANI/CDC supercapacitors. The fabricated asymmetric devices had an average capacitance of 250–270 mF, ESR of 20–23 Ω, and leakage current of 140–150 µA, depending on the PANI/CDC variant used. Energy densities of 4.8 Wh kg-1 and 4.9 Wh kg-1, power densities of 1.6 kW kg-1 and 1.5 kW kg-1, and capacitance retention rates of 93 % and 97 % after 2,000 charge-discharge cycles, were achieved with PANI/CDC (10:1) and (30:1) variants, respectively.

Attaining superior performance in an aqueous hybrid supercapacitor based on N-Doped highly porous carbon spheres and N-S dual doped Co3O4

Cobalt oxide (Co3O4) has seen a significant interest for its application as an electrode for supercapacitors, due to its cost-effectiveness, high theoretical capacitance and outstanding redox activity. However, Co3O4 exhibits poor electrical conductivity and cycle life restricting its high-power energy storage applications. High porosity carbons are materials of choice for applications in electric double layer charge storage but suffer from poor energy densities due to limited charge storage capabilities. Here we propose a hierarchical functionalization strategy to develop N, S co-doped Co3O4 and N doped high porosity carbon micro-spheres for efficient and durable hybrid supercapacitor. Benefiting from the structural eminence, improved electrical conductivity and high quantity of N content, the heteroatom enriched N, S co-doped Co3O4 and N doped porous carbon spheres demonstrates superior electrochemical performance. Moreover, hybrid supercapacitor cell with N, S co-doped Co3O4 as a cathode and N doped porous carbon spheres as anode deliver a high specific energy of 52 Wh kg-1 at power density of 1462 W kg-1 coupled with the capacity retention of 95 % after 5,000 charge-discharge cycles.Therefore, by improving both anode and cathode simultaneously can be considered an effective approach to enhance energy storage capabilities of hybrid supercapacitors while maintain exceptionally high-power densities.

Boron-doped diamond decorated with metal-organic framework-derived compounds for high-voltage aqueous asymmetric supercapacitors

Conductive diamond has been recognized as a promising electrode material for supercapacitors due to its excellent stability and broad electrochemical potential window. To enhance the performance of diamond-based supercapacitors, this study focuses on two key strategies: incorporating redox-active species on the electrodes and/or in the electrolytes to increase the capacitance, and constructing asymmetric supercapacitors to expand the operating voltage range. In this context, pseudocapacitive Co3O4@boron doped diamond (BDD) and Bi–Bi2O3@BDD were synthesized using metal-organic framework (MOF) decorated BDD of Co-MOF@BDD and Bi-MOF@BDD as precursor materials, respectively. An aqueous asymmetric supercapacitor was then assembled using a pseudocapacitive electrode/redox electrolyte system of Co3O4@BDD | 3.0 M KOH+0.05 M K3Fe(CN)6/K4Fe(CN)6 as the positive compartment, and Bi–Bi2O3@BDD | 3.0 M KOH as the negative compartment. The resulting device demonstrated a wide operating voltage of 1.7 V, a maximal energy density of 10.0 Wh L−1 at a power density of 333.2 W L−1. The remarkable performance can be attributed to the Faradaic redox reactions involving [Fe(CN)6]3-/4-, Co3+/Co4+, Bi0/Bi2+/Bi3+ in the electrode materials and electrolytes. This work presents a novel way for fabricating aqueous supercapacitors with high voltage, high energy and power densities, offering significant potential for various energy storage applications.

Manganese and Cobalt Heterostructures in Carbon Aerogels for the Improved Electrochemical Performance of Supercapacitors

Manganese and Cobalt Heterostructures in Carbon Aerogels for the Improved Electrochemical Performance of Supercapacitors

Optimization of pore structure and surface chemical properties of activated carbon fiber via liquid-phase stabilization for enhanced supercapacitor performance

Stabilization is a crucial factor influencing both the structure and properties of pitch-based activated carbon fiber (PACF). The traditional air stabilization not only requires a high softening point of precursor but also consumes a considerable amount of time and energy. In this study, liquid-phase stabilization was employed to streamline the preparation process, and its influence on resultant PACF was investigated. The oxidation stabilization process is fully conducted in just 1 h through liquid-phase stabilization. The obtained N-doped pitch-based activated carbon fiber (NPACF) possessed higher specific surface area and higher nitrogen content (3.77 wt%) compared to PACF obtained by air oxidization. The specific capacitance of NPACF electrode attained 325 F/g at 0.5 A/g. The device based on two equal NPACF electrodes exhibited a specific capacitance of 222 F/g at 0.5 A/g, an energy density of 7.6 Wh/kg at 248 W/kg, and excellent cycle stability of 92.0 % after 10,000 cycles.

Synergistic Effects of ZnO@NiM′-Layered Double Hydroxide (M′ = Mn, Co, and Fe) Composites on Supercapacitor Performance: A Comparative Evaluation

Synergistic Effects of ZnO@NiM′-Layered Double Hydroxide (M′ = Mn, Co, and Fe) Composites on Supercapacitor Performance: A Comparative Evaluation

The g-C3N4/rGO composite for high-performance supercapacitor: Synthesis, characterizations, and time series modeling and predictions

Supercapacitors have gathered significant interest in addressing the increasing need for energy storage devices with high power and energy densities. This study introduces a composite framework designed to enhance supercapacitor performance by leveraging the synergistic effects of g-C3N4/rGO composite. The composite electrode, which combines rGO for high conductivity and g-C3N4 for rapid ion diffusion, demonstrates excellent supercapacitor performance. The synthesized materials were characterized using different analytical tools such as X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, Scanning and Transmission electron microscope, and X-ray photoelectron spectroscopy. The composite electrode exhibited outstanding performance characteristics, including a specific capacitance of 407.7 F/g, an energy density of 11.4 W h/kg, and a high power density of 186.7 W/kg. Kinetic analysis revealed that the g-C3N4/rGO composite electrode has a dominant diffusive controlled process. The g-C3N4/rGO electrode also demonstrated exceptional durability, maintaining remarkable capacitance retention even after the 5000th charge/discharge cycles. Moreover, the cyclic stability and Coulombic efficiency of the g-C3N4/rGO electrode were modeled and predicted by utilizing the time series analysis technique (Holt-Winters exponential smoothing). Considering the overall results, the g-C3N4/rGO composite electrode has a great potential for energy storage applications.

Composite Track-Etched Membranes: Synthesis and Multifaced Applications.

Composite track-etched membranes (CTeMs) emerged as a versatile and high-performance class of materials, combining the precise pore structures of traditional track-etched membranes (TeMs) with the enhanced functionalities of integrated nanomaterials. This review provides a comprehensive overview of the synthesis, functionalization, and applications of CTeMs. By incorporating functional phases such as metal nanoparticles and conductive nanostructures, CTeMs exhibit improved performance in various domains. In environmental remediation, CTeMs effectively capture and decompose pollutants, offering both separation and detoxification. In sensor technology, they have the potential to provide high sensitivity and selectivity, essential for accurate detection in medical and environmental applications. For energy storage, CTeMs may be promising in enhancing ion transport, flexibility, and mechanical stability, addressing key issues in battery and supercapacitor performance. Biomedical applications may benefit from the versality of CTeMs, potentially supporting advanced drug delivery systems and tissue engineering scaffolds. Despite their numerous advantages, challenges remain in the fabrication and scalability of CTeMs, requiring sophisticated techniques and meticulous optimization. Future research directions include the development of cost-effective production methods and the exploration of new materials to further enhance the capabilities of CTeMs. This review underscores the transformative potential of CTeMs across various applications and highlights the need for continued innovation to fully realize their benefits.

Electrospun Mn1-xCoxFe2O4 (x=0–0.7) nanofibers for supercapacitors and oxygen evolution reaction

Cobalt manganese ferrite nanofibers (Mn1-xCoxFe2O4; x = 0, 0.3, 0.5, 0.7), were synthesized using sol-gel electrospinning technique. The impact of cobalt incorporation on physical and electrochemical properties of manganese ferrite nanofibers was investigated. The XRD peaks confirmed the formation of a cubic spinel phase and lattice parameter decreased gradually with increasing cobalt concentration. SEM analysis revealed the nanofibers with diameters in the range of 30–60 nm. VSM analysis showed that magnetic parameters such as coercivity, and saturation magnetization were enhanced by cobalt substitution and the sample Mn0.3Co0.7Fe2O4 showed the highest saturation magnetization and coercivity. DRS analysis exhibited that the incorporation of cobalt in the manganese ferrite reduced the band gap energy. The supercapacitive performance of Mn1-xCoxFe2O4 electrodes was investigated using CV, GCD and EIS in 3 M KOH electrolyte solution. The highest specific capacitance (453 F g−1) was obtained with long cycling stability (94.6 % retention after 4000th cycles) for Mn0.7Co0.3Fe2O4. Furthermore, an asymmetric supercapacitor (ASC) was made with reduced graphene oxide (rGO) and Mn0.7Co0.3Fe2O4 as anode and cathode electrodes, respectively. The Mn–CoFe2O4//rGO ASC revealed an impressive energy density of 50.2 Wh kg−1 at a power density of 750 W kg−1. The electrocatalytic oxygen evolution reaction (OER) performance of the Mn0.7Co0.3Fe2O4 and MnFe2O4 catalysts were also investigated in 1 M KOH alkaline electrolyte. Experiments demonstrated that the Mn0.7Co0.3Fe2O4 nanofiber catalyst had a lower overpotential (201 mV) at 10 mA cm−2, a small Tafel slope (106 mV dec−1), a larger ECSA (176 cm2), a greater TOF (7.68 × 10−4 s−1), and better long-term durability (96.3 % for 12 h) than MnFe2O4 for OER. This highlights the potential of the synthesized Mn0.7Co0.3Fe2O4 electrode for supercapacitor and oxygen evolution reaction.

Unveiling magnetite metal-organic frameworks for asymmetric pseudo-supercapacitor with high energy density and magnetocapacitance

Utilizing innovative techniques for electrode fabrication and incorporating novel energy storage concepts through external stimuli forces is crucial for enhancing the specific capacity and commercial feasibility of energy storage devices. The performance of supercapacitors hinges on both capacitive behavior, which enhances charge-discharge characteristics and power density, and ion-diffusion behavior, which boosts energy density. This study delves into the impact of external magnetic fields on supercapacitor performance by enhancing pseudo-capacitive behavior through a facile redox pathway and promoting the diffusion coefficient of the electrolyte. We presented magneto-electrophoretic deposition (M-EPD) to apply a high-surface-area zeolitic imidazolate framework (ZIF), which serves as a robust binder-free strategy. Specifically, the Fe3O4-ZIF-67 nanocomposite is uniformly supported on ferromagnetic nickel foam (NF) and demonstrates an impressive specific capacitance of 656.7 F g−1 (328.4 C g−1) at 1 A g−1. In addition, coin cell supercapacitors assembled with Fe3O4-ZIF-67/NF as positive and Fe3O4-ZIF-67-MWCNT/CF as negative electrodes achieve outstanding energy density (103.3 W h kg−1) at a power density of 750 W kg−1, coupled with excellent cycling stability (83.61 % capacity retention) after 10,000 cycles at 20 A g−1. Notably, the cell exhibits superior magnetocapacitance and the highest diffusion coefficient under an external magnetic field of 100 mT. The energy density reaches 163.2 W h kg−1 at a power density of 750 W kg−1, with a coulombic efficiency of 77.7 %. This represents a 1.58-fold enhancement compared to the absence of the magnetic field. The results demonstrated that ferromagnetic coupling between metal−oxygen−metal centers is enhanced via oxygen 2p orbitals, thereby creating a facile pseudocapacitance mechanism. The ZIF-67 shell further regulates the charge-discharge behavior of the electrode through the interplay between diffusive and capacitive mechanisms. This work introduces a promising new approach for preparing high-surface-area MOF-based electrodes and stimuli-responsive, high-performance electrochemical energy storage devices.

Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g−1 specific capacitances at 0.5 A g−1 current density, respectively. Whereas their energy densities were 44 and 46 Wh kg−1 at 350 and 423 W kg−1 power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g−1 even at high current density (20 A g−1), while the one assembled with C-KOH stored 54 F g−1. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g−1 over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.

Superior performance of asymmetric supercapacitor based on Cu doped bismuth ferrite electrode

Electrochemical energy storage devices, like supercapacitors and batteries, are needed to meet the constantly increasing demands of portable energy devices. Many types of supercapacitor electrodes were synthesized and reported which include carbon-based materials, polymers, oxides and perovskites. In this work, we report on the fabrication of Cu doped bismuth ferrite (Cu-BiFeO3, Cu-BFO) nanoparticles via sol-gel procedure. In most of the doping cases the costly rare earth elements like La, Nd, Sm, Ce and Yb are used to replace Bi. Electrodes of Bi1-xCuxFeO3 where x have the values 0.0, 0.025, 0.05, 0.075, 0.1 and 0.15 were deposited on graphitic sheets. Optimum Cu doping value was found to be at x = 0.05. Cu2+ ions doping in place of Bi3+ ions will reveal the roles of oxygen vacancies, as determined from XPS. The estimated values of specific capacitance was found to be 732 F/g at 0.5 A/g for the electrode at x = 0.05 in three electrode system. 5%Cu-BFO//Carbon black asymmetric supercapacitor (ASC) device can be charged and discharged reversibly at cell voltage of 0.0 up to 1.5 V when using a 0.5 M Na2SO4 aqueous electrolyte. This configuration allows the ASC device to deliver a great energy density of 37.25 Wh/kg at a power density of 752 W/kg. The ASC device demonstrates excellent cycling stability, retaining 88.64 % of its initial specific capacitance after 5000 cycles. Increasing the Cu content up to 15 % causes instability in the crystal structure of BFO resulting on phase segregation into Bi2Fe4O9 along with BFO and deterioration in the electrode overall performance. XPS showed that replacement of Cu2+ in place of Bi3+ disturbs the neutrality and the chemical environment of the compound. Hence to achieve neutrality and ionic balance, oxygen vacancies increase and the Fe2+/Fe3+ ratio increases as well. Both oxygen vacancies and the change in the Fe ions ratio reduce electrochemical impedance and give rise to charge density. The homogenous distribution of the pores at x = 0.05 contributed greatly to its fast electrolyte ion diffusion that improved the observed capacitive properties. One has to mention here, that despite doping that contains ions with different ionic size and/or different oxidation state is unfavorable, to some extent, due to the changes they produce in the electronic structure and the chemical environment, nevertheless it is sometimes beneficial in creating new parameters in the structure that promote specific application like in the case of the current work, oxygen vacancies, increase in surface area and the mixed state valency.