Symmetric Supercapacitor Research Articles

Optimizing symmetric supercapacitor performance through rational design of Zr/Cu/Fe Oxide-Modified Poly(vinyl alcohol) hybrid nanofibers

Present work, ZrO2/CuO/PVA (ZC-PVA), ZrO2/Fe2O3/PVA (ZF-PVA) and ZrO2/CuO/Fe2O3/PVA (ZCF-PVA) nanofibers were synthesized by cost effective electrospinning method. The ZCF-PVA nanofiber prepared in this study were subjected to analysis using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques, individually. XRD was employed to ascertain both the structure and crystallite size of the synthesized materials. SEM and FT-IR analysis were used to identify the morphology and functional groups present in the prepared ZC-PVA, ZF-PVA and ZCF-PVA nanofibers. XPS confirmed the surface elemental composition and oxidation states of Zr4+, Cu2+, and Fe3+ in ZCF-PVA nanofiber comprising ZrO2, CuO, and α-Fe2O3. In three electrode configuration ZCF-PVA nanofiber shows significantly higher specific capacitance of 824F/g at 1 A/g current density under 1 M KOH. The generation of synergic effect between multi valence oxidation states of mixed metal oxides and polymer (ZCF-PVA) enhances the capacitive behavior. The ZCF-PVA symmetric device exhibits 184F/g at 0.5 A/g current density with 91 % capacitance retention and 94 % of coulombic efficiency even after 5000 cycles at 3 A/g of current density.

Nitrogen and phosphorus enriched nanoporous carbonaceous material for gas sorption and supercapacitor applications

Nitrogen and phosphorous-enriched heteroatoms-based nanoporous carbonaceous material (designated as HPHMC900) possesses a high surface area of 1668 m2 g−1 was synthesized. HPHMC900 captures 5.6 and 3 mmol g−1 of CO2 and CH4 at 273 K and 1 bar, respectively. Further, the material has 11.95 mmol g−1 of H2 adsorption capability at 77 K and 1 bar. HPHMC900 has been investigated for supercapacitor application. Further, a symmetric supercapacitor device (SSD) fabricated using the HPHMC900, has a specific capacitance (Csp) of 233 F g−1, energy (E) of 46.6 Wh kg−1, and power (P) of 289 W kg−1, respectively. The high Csp and high energy were achieved at low-concentrated aqueous electrolyte (0.5 M KOH), without using any redox-active agents. Further, it shows 100 % coulombic efficiency and initial capacitance retention (94.9 %) after 10,000 cycles. This research elucidates the correlation between high surface area and heteroatom enrichment with enhanced charge storage and gas adsorption efficiency.

Tailoring surface terminals of Ti3C2Tx MXene microgels via interlayer domain-confined polyphosphate ammonium for flexible supercapacitor applications

The MXene material shows potential for flexible energy storage devices due to its high pseudocapacitance and mechanical flexibility. However, MXene nanosheet self-stacking and –F terminal functional groups can hinder active site and ion dynamics, thus affecting the energy storage performance. Herein, we present an interlayer domain-confined strategy that involves the introduction and crosslinking of ammonium polyphosphate (APP) confined to the interlayer of Ti3C2Tx MXene sheets, which induces gelation of the MXene to form a 3D network structure and enlarge their interlayer spacing. And then the cross-linked APP is converted into nitrogen and phosphorus terminals on Ti3C2Tx MXene via thermal treatment. The nitrogen terminals in the form of the pyrrole nitrogen and pyridine nitrogen, and phosphorus terminals of P–O bonds enhance the activity of the redox reaction and the dynamics of the ions, resulting in the boosted energy storage capacity of MXene. The density functional theory (DFT) calculations reveal that nitrogen-phosphorus co-doping modulates the surface electronic states of MXene and contributes to the increase of the electrical conductivity of Ti3C2Tx MXene. As a supercapacitor electrode, Ti3C2Tx MXene with N/P terminals exhibits a higher specific capacitance of 597.8 F/g (1777F cm−3) than the raw Ti3C2Tx MXene (384 F/g). In addition, the quasi-solid state flexible symmetric supercapacitor assembled by Ti3C2Tx MXene with N/P terminals can achieve an energy density of 12.5 Wh kg−1 at a power density of 250 W kg−1. Therefore, this work provides a new strategy for terminal modification of MXene and high-performance MXene supercapacitors.

A novel benzoquinone‐azo linked polymer‐based active electrode material for high‐performance symmetric pseudocapacitors

AbstractPseudocapacitors (PSCs) have attracted researcher's attention due to their potential electrochemical performance as the power source for electronic devices. However, to maintain the high electrochemical properties of pseudocapacitive materials becomes critical. Therefore, the active electrode materials design and synthesis is a challenging task. To tackle these problems, herein, we rationally designed new polymer based on benzoquinone with azo linker. The polymer AZO‐BQ‐P was synthesized and tested for their energy storage applications in combination with graphite foil (GF). In three‐electrode supercapacitor (SC) device, the AZO‐BQ‐P/GF electrode exhibits excellent specific capacitance (Csp) of about 306.27 F g−1 at 0.5 A g−1 current density and higher cycling stability. The pseudocapacitive performance of SC cells result from synergistic effect of AZO‐BQ‐P and GF and due to faster electrolyte ion diffusion and increased availability at electrode/electrolyte interfaces. Furthermore, AZO‐BQ‐P/GF electrode was employed to fabricate two‐electrode AZO‐BQ‐P/GF//AZO‐BQ‐P/GF symmetric SC device. The optimal SSC device shows a Csp reaching 200 F g−1 at 0.5 A g−1, which is an impressive value. Also, it exhibits remarkable cycling stability with 86.18% Csp retention after 5000 galvanostatic charging–discharging (GCD) cycles at 3 A g−1. The SSC device applying AZO‐BQ‐P/GF electrode delivers an excellent energy density (ED) of 25.00 Wh kg−1 at 900.00 W kg−1 power density (PD). Thus, the novel polymer design offers efficient electrode materials to enhance the pseudocapacitive electrochemical performance of the SSC device. This concept can be extended for fabricating other electrochemical systems and accelerate its applications for modern electronic devices.

Sustainable graphitic carbon derived from oil palm frond biomass for supercapacitor application: Effect of redox additive and artificial neural network‑based modeling approach

One-step pyrolyzed graphitic carbon (GC) derived from oil palm frond biomass was synthesized at different durations (1, 3, and 5 h) without utilizing of activating agent. The optimum GC-5 h exhibited a honeycomb-like structure (1.9 nm), high carbon content (84 %), graphitic peak at 2θ ∼ 24.2°, and wide pore size (2.17 nm) suitable to accommodate solvated electrolyte ions. Symmetric supercapacitor (SSC) cells with three redox additives (hydroquinone (HQ), ammonium monovanadate (AM), and potassium ferrocyanide (PF)) in H2SO4 electrolyte are tested. The GC-5 h SSC shows a CS of 595F/g in 0.01 M HQ/H2SO4 electrolyte at a current density of 3 A/g. The cell exhibits an energy density (ED) of 22 Wh kg−1 and a power density (PD) of 2,400 W kg−1. It demonstrates a capacitance retention of 93 % after 10,000 cycles. To develop the intricate interactions between the electrode structure, active operating circumstances, and electrochemical performance of the SSC, an artificial neural network (ANN) approach was applied herein. The model uses the Levenberg-Marquart training method, incorporating the Tanh and Purelin activation functions. The data demonstrate that the constructed ANN model can predict the SSC with values that nearly match the experimental data with an MSE of 6.8122 × 10−5 and R of 0.9989.

Hydrothermal assisting biomass into a porous active carbon for high-performance supercapacitors

Biomass contained significant amounts of lignin, cellulose and hemicellulose and these high crystallinity results in sub-optimal electrochemical properties. Herein, a hydrothermal method was employed to intentionally weaken the structural integrity of hemp fibers and eliminate cellulose impurities. After undergoing KOH activation, the resulting product achieved a maximum specific surface area of 1644.3 m2 g−1. In a three-electrode test, the specific capacitance of this electrode material was 255.6 F g−1 at a current density of 1 A g−1, representing a nearly double enhancement over the non-hydrothermally treated sample. Furthermore, the assembled symmetric supercapacitor has a specific capacitance of 56.9 F g−1 at 1 A g−1 and a capacitance retention of 102 % after 10,000 charge/discharge cycles (10 A g−1). Its maximum power density was 725 W kg−1 at an energy density of 16.6 Wh kg−1. The desirable capacitive properties indicated that the hydrothermal pretreatment method was expected to have wider applications in the preparation of other biomass-based electrode materials.

Eu-viologen based bimetal–organic frameworks nanosheets with Mn atoms anchored on Eu-µ-O skeletons as high-performance negative electrode for flexible asymmetric supercapacitors

Exploring advanced negative electrode materials is imperative to develop high-performance asymmetric supercapacitors for breaking through current energy density limits of supercapacitors, but remains challenging. Herein, a strategy is proposed to create a novel negative electrode by anchoring Mn single-atoms on Eu-viologen metal–organic frameworks (EV-Mn MOFs) nanosheets flowery architectures that self-supported on oxidized carbon cloths (OCC). Such EV-Mn/OCC achieves a negative broadened voltage window (−1 ∼ 0 V) and boosted areal capacitance (840.82 mF cm−2), which is four folds of the isostructural EV/OCC without Mn atoms and surpasses most of currently reported negative electrodes. Also, the EV-Mn/OCC manifests good cycling stability (∼80 % retention for 10,000 cycles). As deduced by the thorough studies of X-ray absorption fine spectra and X-ray photoelectron spectroscopies, the enhanced pseudocapacitance of EV-Mn/OCC definitely correlates to the valence modulation of Mn and Eu through internal electron transfer via Eu-O-Mn bonds on Eu-µ-O skeleton in EV-Mn MOFs. Subsequently, the constructed flexible all-solid-state symmetric supercapacitors employing EV-Mn/OCC as negative electrode can deliver a high energy density (86.89 μWh cm−2) at 1600 μW cm−2, outperforming many asymmetric devices based on traditional negative electrode materials. This work can spur the development of single-atom metallic electronic-modulation strategy for MOFs negative electrode material (MOFs-NEM), and accelerate their applications in flexible energy conversion and storage devices.

Performance study of high energy storage supercapacitor from waste corn husk biomass electrode materials

Waste biomass carbon materials are used as green and environmentally friendly electrode materials for supercapacitors (SCs) have great development prospects, therefore, miscellaneous elements-rich and recycled renewable porous carbon materials have important applications value in the field of energy storage device. In this paper, waste corn husk as biomass precursor to prepare corn husk porous carbon (CHPC) using two steps of high-temperature carbonization and KOH activation. The CHPC-2 optimized by KOH shows a specific surface area (SSA) of 1103 m2 g−1 and a total pore volume of 0.83 cm3 g−1, achieving a high specific capacitance of 413.4 F g−1 at 0.5 A g−1. After 10,000 cycles, only 4.17 % of the capacitance was lost. In a two-electrode system with 1 M Na2SO4 as the electrolyte, CHPC-2//CHPC-2 exhibits a specific capacitance of 333 F g−1 at a wide voltage window of 0–1.8 V, and energy density of 37.46 Wh Kg−1 when power density is 450 W kg−1, which possesses the capacitance retention rate of 85.16 % after 5000 cycles. The assembled symmetrical SCs contain capacitance of 308.79 F g−1, and 21.02 Wh kg−1 under a power density of 350 W kg−1 in PVA/KOH gel electrolyte. Consequently, CHPC materials provide a scientific and reasonable research idea for the development of SCs with inexpensive, non-polluting, and high energy density.

Molten salt-mediated hierarchical porous carbon derived from biomass waste for high-performance capacitive storage

Biomass-derived carbon (BDC) materials are the suitable precursors for the fabrication of carbon electrodes of supercapacitors because of the sustainability, environmental friendliness, power capability, and structural diversity. The fabrication of BDC with low cost and excellent electrochemical properties is important for the practical applications of BDC in energy storage fields. Herein, ambrosia melon peels are used as carbon precursors for the fabrication of sustainable BDC electrodes through the molten salt-mediated pyrolysis procedure. The ambrosia melon peels-derived porous carbon (AMPPC) possesses high specific surface area of 529.9 m2 g−1. The AMPPC electrode shows the charge storage behavior of electrical double-layer capacitance with high ionic conductivity, high specific capacitance (218.3 F g−1 at 0.5 A g−1) and outstanding rate performance. In addition, the symmetric supercapacitor based on the AMPPC electrodes presents high specific energy density and specific power density (8 kW kg−1). It can be used as energy source to power helicopter model, clock, and calculator. Thus, the work gives an inspiration of design of BDC from the low-cost biomass waste and provides a simple way for the fabrication of BDC for the carbon electrodes of supercapacitors, lithium-ion batteries and so on.

Setaria viridis-like hierarchical structure TiN nanofibers for high-performance supercapacitor

A setaria viridis-like TiN nanofibers with hierarchical structure (noted HSTFs) is synthesized via electrospinning and hydrothermal method. The results reveal that the synthesized HSTFs nanofibers belong to the TiN crystalline phase. The surface of the fibers is uniformly distributed with pore-structured nanorods, which have an average diameter of 55 nm. The HSTFs exhibits a higher specific surface area. Comparing to the TFs||TFs symmetric supercapacitor device, the HSTFs||HSTFs device demonstrates a significantly higher specific capacitance of 177 F g−1 at a current density of 10 mA g−1. The enhanced electrochemical performance is attributed to the hierarchical and porous structure of TiN fibers, which provides a larger surface contact area and more active sites. This structure is conducive to the construction of a conductive network and improves the reversible proton insertion and chemisorption of electrolyte-electron. This research presents a promising approach for the design and synthesizes of high-performance supercapacitor materials.

Optimizing Electrodeposition of Polyaniline on Various Woven Steel Mesh Sizes for Enhanced Supercapacitor Performance.

The development of efficient supercapacitors hinges on the innovation of superior electrodes, which are pivotal in augmenting their energy storage capabilities. Supercapacitors, recognized for their high-power density and extended cycle life, play a crucial role as sustainable solutions in addressing energy storage challenges. A fundamental aspect of supercapacitor functionality involves the electrode material, which works in concert with other key components such as the current collector, separator, and electrolyte. This study focuses on evaluating the impact of the current collector material on the performance of symmetric supercapacitors. We investigated the electropolymerization of polyaniline on woven steel mesh current collectors of varying mesh sizes, ranging from 20 to 200 mesh per inch, using assorted deposition conditions. The electrochemically modified woven steel meshes were utilized to construct symmetric supercapacitors. The electrochemical performance of the assembled supercapacitors, configured in a two-electrode system, was investigated using a variety of electrochemical techniques to better understand the kinetics of electrolyte ion migration. Notably, the 20-mesh size, characterized by the fewest pores per inch, demonstrated superior performance with an optimum capacitance of 4730 mF/cm2, an energy density of 317.8 μWh/cm2, and a power density of 400 μW/cm2 at a current density of 1 mA/cm2.

Advancing Electrochemical Energy Storage: The Synergistic Impact of Sulfur Nano-Confinement in Hierarchically Porous Jute-Derived Activated Carbon for Enhanced Supercapacitor Performance

The availability of energy is a cornerstone for the modernization, automation, and economic growth of nations. With the rapid depletion of fossil fuels and rising environmental concerns, such as CO2 emissions leading to global warming, there has been an intensified search for alternative, renewable energy sources like solar and wind power. However, their intermittent nature necessitates robust electric energy storage systems for effectively harnessing these resources. Electrochemical energy storage devices, particularly batteries and supercapacitors, have emerged as a focal point of recent research due to their potential to bridge this gap. While supercapacitors are known for their high power density and long cycle life, they typically exhibit limited energy density. Recent advancements have shown that composites combining carbonaceous materials with redox-active nanomaterials can significantly enhance supercapacitors' electrochemical performance. In this context, our research explores the development of hierarchically porous activated carbon nanosheets (JAC) derived from jute, an abundantly available biomass. Using a straightforward pyrolysis process, we have investigated its potential in supercapacitor applications. The prepared JAC, when employed as an electrode material in a symmetric supercapacitor with a glycerol-based bio-electrolyte, demonstrated higher specific capacitance compared to its commercial counterparts. Further innovation was achieved through the introduction of sulfur doping in JAC (S-doped JAC). This novel approach leverages the inherent porous nanosheet morphology of JAC and heteroatom modification to yield exceptional electrochemical performance. Our findings reveal that the S-doped JAC composite, particularly the variant with 25% sublimed sulfur (SJAC-25), significantly outperforms the standard JAC in terms of specific capacitance (230 F/g vs. 130 F/g at 1.0 A/g current density) in a glycerol-KOH bio-based electrolyte. Moreover, a symmetric supercapacitor assembled with SJAC-25 showcased an impressive energy density of 32 Wh/kg at a power density of 500 W/kg, maintaining 28 Wh/kg even at a heightened power density of 2500 W/kg. This demonstrates its capability to retain high energy efficiency under varying power conditions. Additionally, the SJAC-25 based supercapacitor exhibited remarkable durability, with about 94% capacitance retention and 86% Coulombic efficiency after 10,000 charge-discharge cycles. Our research not only highlights the potential of processed bio-waste as a viable material for energy storage but also introduces an advanced, scalable, and straightforward synthesis method. This method could pave the way for the preparation of highly porous and sulfur-doped nanoporous carbon, setting a new benchmark for high-performance electrochemical energy storage applications.

Electrochemical Performance and Characterisation of Chemically Treated Conductive PLA Fused Deposition Modelling (FDM) Current Collectors within Additively Manufactured (3D-Printed) Symmetric Carbon Supercapacitors

Within the fields of materials science, producing reliable, long-lasting, and efficient energy storage devices to meet the world’s energy needs remains a foremost research goal. 3D-printing (also known as Additive Manufacturing) provides many benefits to this research [1-8], allowing for excellent customization and freedom of design, while eliminating waste material in the manufacturing process. Wearable electronics, medical implants, and the Internet of Things will doubtless benefit from the advantages provided by additive manufacturing.Our previous work compared the electrochemical performances of symmetric carbon-based supercapacitor devices made using two 3D-printing techniques, SLA (stereolithography) and FDM (fused deposition modelling). Though possessing excellent cycle life, the conductive polylactic acid (PLA) FDM printed current collectors suffered from relatively high resistance and poor cyclic voltammetry curves (far from the rectangular shape of ideal electronic double-layer capacitors). This study aims to improve the conductivity of the FDM current collectors via chemically induced surface modification [9]. Both dimethylformamide (DMF) and aqueous potassium hydroxide (KOH) treatments are used for this purpose. The untreated, DMF-treated, and KOH-treated FDM current collectors are loaded with 1:1 by mass single-walled carbon nanotubes and graphene nanoplatelets carbon slurry, placed within stereolithography (SLA) 3D-printed casings [10], and assembled as supercapacitor cells (separated by glass microfiber filter separators soaked in 6 M aqueous KOH electrolyte).This works shows how DMF treatment method results in little change in electrochemical performance compared to the untreated FDM current collector cells, but pre-treatment in a solution of KOH identical to the cell electrolyte markedly improves the current collector conductivity. The KOH treatment provides a tenfold decrease in the FDM current collector resistance, which correlates with the improved cyclic voltammetric response. Galvanostatic charge-discharge tests reveal the effect of these treatments on specific capacitance, charge-discharge response, efficiency, and rate capability for these printed cells. The pre-treatment confirms that the cell electrolyte does not limited long term performance by interacting with the PLA current collector in 3D printed supercapacitor cells and tests using other inorganic active materials will also be shown.

3D Printed Symmetric Carbon Supercapacitors: A Study Comparing Electrochemical Performance and Cycle Life Depending on 3D Printing Technique and Materials

With the ongoing global energy crisis, producing reliable and efficient methods of energy storage remains an integral part of cutting-edge materials research. Within this topic, 3D-printing (also known as additive manufacturing) is evolving from a niche hobby to a reliable scientific tool for materials science research [1-3]. 3D-printing energy storage materials provides unparalleled levels of customisation [4-9] and freedom of design, while also eliminating waste material during the manufacturing process.3D-printing energy storage materials has been widely covered, but usually just focuses on one method of 3D-printing. Directly comparing more than one 3D-printing method within a single energy storage study is far more seldom researched. This work directly compares the electrochemical performances of symmetric carbon-based supercapacitor devices made using two 3D-printing techniques, SLA (stereolithography) and FDM (fused deposition modelling). Two cell types are made in this study, one with gold-sputtered SLA-printed current collectors, the other with conductive PLA (polylactic acid) FDM-printed current collectors. Carbon-based electrode (various combinations of SWCNT, GNP, Super-P, PVDF) slurries and aqueous 6M KOH electrolyte are implemented in these cells. The benefits and limitations of these 3D-printing methods are directly compared, with the electrochemical performance of the supercapacitor cells being analysed using cyclic voltammetry and galvanostatic charge-discharge tests.The sputtered conductive SLA current collector cells display better conductivity and more ideal rectangular cyclic voltammetry curves for electronic double-layer capacitors (EDLCs) but suffer from poor cycle life in initial experiments (~5,000 charge-discharge cycles before losing all specific capacitance). The FDM current collector cells have poorer conductivity, less ideal cyclic voltammetry curves, and are less structurally sound (causing some electrolyte leakage over long term cycling) but offer extremely stable cycle life for supercapacitor cells, retaining most of their specific capacitance after 100,000 charge-discharge cycles. The cycle lives of the gold-sputtered SLA current collector cells are greatly improved after several changes made during the study, such as reducing the voltage window from 0.0-1.0 V to 0.2-0.7 V, and exploring additives for the carbon-based slurry electrodes, such as Super-P and PVDF (polyvinylidene fluoride).

Pseudocapacitive Storage in Molybdenum Oxynitride Nanostructures Reactively Sputtered on Stainless-Steel Mesh Towards an All-Solid-State Flexible Supercapacitor

Exploiting pseudocapacitance in rationally engineered nanomaterials offers greater energy storage capacities at faster rates. The present research reports a high-performance Molybdenum Oxynitride (MoON) nanostructured material deposited directly over stainless-steel mesh (SSM) via reactive magnetron sputtering technique for flexible symmetric supercapacitor (FSSC) application. The MoON/SSM flexible electrode manifests remarkable Na+-ion pseudocapacitive kinetics, delivering exceptional ~881.83 F.g-1 capacitance, thanks to the synergistically coupled interfaces and junctions between nanostructures of Mo2N, MoO2, and MoO3 co-existing phases, resulting in enhanced specific surface area, increased electroactive sites, improved ionic and electronic conductivity. Employing 3D Bode plots, b-value, and Dunn’s analysis, a comprehensive insight into the charge-storage mechanism has been presented, revealing the superiority of surface-controlled capacitive and pseudocapacitive kinetics. Utilizing PVA-Na2SO4 gel electrolyte, the assembled all-solid-state FSSC (MoON/SSM||MoON/SSM) exhibits impressive cell capacitance of 30.7 mF.cm-2 (438.59 F.g-1) at 0.125 mA.cm-2. Moreover, the FSSC device outputs superior energy density of 4.26 μWh.cm-2 (60.92 Wh.kg-1) and high power density of 2.5 mW.cm-2 (35.71 kW.kg-1). The device manifests remarkable flexibility and excellent electrochemical cyclability of ~91.94% over 10,000 continuous charge-discharge cycles. These intriguing pseudocapacitive performances combined with lightweight, cost-effective, industry-feasible, and environmentally sustainable attributes make the present MoON-based FSSC a potential candidate for energy-storage applications in flexible electronics. Figure 1

Boosting supercapacitor performance: Sb2O3 nano-blocks on rGO sheets for enhanced energy storage

In this work, the synthesis of antimony(III) oxide (Sb2O3) nanoblocks/reduced graphene oxide (rGO) sheets was obtained by a straightforward hydrothermal method. Sb2O3/rGO composites were prepared with various ratios of rGO. The results indicated that the Sb2O3/15 mg rGO composite had remarkable electrochemical performance. It displayed a good electrochemical efficiency, with a high specific capacitance of 151.89 F g−1 at 1 A g−1. Furthermore, it demonstrated a significant cycling stability, retaining 80 % of its initial capacitance after 5 K charge/discharge cycles. A symmetric supercapacitor device was prepared using Sb2O3/15 mg rGO composite as the electrodes for both positive and negative ends. The device exhibited a high specific energy of 44.36 Wh kg−1 and a significant specific power of 850.76 W kg−1. Moreover, it maintained 5.025 Wh kg−1 at a specific power of 7.25 kW kg−1. These results indicated that the Sb2O3/15 mg rGO composite has the potential promising application as an energy-storage electrode material, as no investigations have been conducted on using Sb2O3/rGO as a supercapacitor electrode.

Fabrication of solid-state symmetrical supercapacitor device based on constructed novel Gr-Cu-MoO2 disk electrodes based on Co-replacement reactions

The use of graphite-based substrates has attracted the attention of many researchers due to their high-performance capacitive behavior. Graphite Disk (GD) electrodes due to being more robust and capacity than graphite sheets can be used on an industrial scale. In this research, for the first time, by using the co-replacement method as a straightforward and without wasting energy method, MoO2 and Cu nanostructures with particular morphology were in-situ co-replaced on GD substrates based on commercial graphite and Zn-metal powder. The results of the scanning electron microscopy analysis clearly showed the MoO2–Cu nanosheet formed on the porous GD (PGC) electrode, which has caused a tremendous increase in the capacitance and cyclic stability due to the augment in the surface area and synergistic effect of MoO2–Cu nanostructure. Also, different characterization analysis results confirmed the co-replacement of MoO2 and Cu nanostructures onto the PGD electrode. Electrochemical investigation exhibited that this electrode has an extraordinary capacity of 28526 mF/cm2 at 2 mA/cm2 in 1M H2SO4. The investigation of the capacitive behavior of the MoO2–Cu/PGD supercapacitor device showed that the fabricated supercapacitor device has an astonished capacitance of 4916.98 mF/cm2 (145.27 F/g), power of 18017.34 mW/cm2, and energy density of 4154.84 mWh/cm2 at 1 mA/cm2.

Nanoscale synergy: Optimizing energy storage with SnO2 quantum dots on ZnO hexagonal prisms for advanced supercapacitors

Abstract Electrode materials comprising SnO2 quantum dots embedded within ZnO hexagonal prisms were successfully synthesized for building cost-effective energy-storage devices. Extensive structural and functional characterizations were performed to assess the electrochemical performance of the electrodes. SEM–EDS results confirm a uniform distribution of SnO2 quantum dots across ZnO. The integration of SnO2 quantum dots with ZnO hexagonal prisms markedly improved the electrochemical behavior. The analysis of electrode functionality conducted in a 3 M KOH electrolyte revealed specific capacitances of 949.26 and 700.68 F g⁻1 for SnO2@ZnO and ZnO electrodes, respectively, under a current density of 2 A g⁻1. After undergoing 5,000 cycles at a current density of 15 A g⁻1, the SnO2@ZnO and ZnO electrodes displayed impressive cycling stability, maintaining specific capacitance retention rates of 89.9 and 92.2%, respectively. Additionally, a symmetric supercapacitor (SSC) device constructed using the SnO2@ZnO electrode showcased exceptional performance, exhibiting a specific capacitance of 83 F g⁻1 at 1.2 A g⁻1. Impressive power and energy densities were achieved by the device, with values reaching 2,808 and 70.2 W kg⁻1, respectively. Notably, the SnO2@ZnO SSC device maintained a capacity preservation of 75% throughout 5,000 galvanostatic charge–discharge sequences. The outcomes highlight the potential of SnO2@ZnO hexagonal prisms as candidates for energy-storage applications, offering scalability and cost-effectiveness. The proposed approach enhances the electrochemical performance while ensuring affordability, facilitating the creation of effective and financially feasible energy storage solutions.

Unraveling cation intercalation mechanism in MXene for enhanced supercapacitor performance

MXenes are two-dimensional materials with high electrical conductivity, adjustable composition, and tunable surface terminations, holding promise for supercapacitors (SCs). However, the susceptibility to interlayer restacking and the attachment of inactive -F terminations reduce their capacitances and rate performance. To resolve these issues, electrochemistry-driven cation intercalation (ECI) followed by calcination is proposed to unclog the interlayers and modify surface chemistry simultaneously. It is found that Mn-modified Ti3C2Tz MXene exhibits exceptional volumetric capacitance (1655.5 F cm−3 at 1 mV s−1, 1.5 times higher than that of pristine Ti3C2Tz) and excellent rate performance (72.3 % retention from 1 A g−1 to 50 A g−1) due to the unblocked interlayers and the increased -O terminations. Density Functional Theory (DFT) results reveal that the intercalated Mn2+ displayed the largest formation energy difference, manifesting a great driving force to form active -O terminations, which is crucial for improving electrochemical performance. Kinetic analysis reveals that the intercalated Mn2+ increases the termination-related capacitances (pseudocapacitance and diffusion-controlled capacitance) significantly. Symmetric and asymmetric SCs demonstrate high energy densities at high powers, showing the advance of the Mn-intercalated Ti3C2Tz. The findings clarify how metal cation intercalation affects MXene performance, providing insights for designing MXene-based electrodes in energy storage applications.

Scalable synthesis of 2D-layered Ti3C2 MXene by HF etching method; electrochemical investigations and device fabrication to enhancing capacitive nature

The goal of the current effort is aimed to synthesise the uniform exfoliated titanium carbide (Ti3C2) MXene sheets by utilising hydrofluoric (HF) acid to remove/etch “aluminium” from the parental Ti3AlC2 MAX phase. The Ti3C2 MXene was investigated by structural analysis using X-ray diffraction (XRD), Higher Resolution Transmission Electron Microscope (HRTEM), Scanning electron microscope (SEM), and EDS with mapping for morphological and elemental analysis, Moreover, the Ti3C2 MXene was studied its electrochemical properties to electrochemical energy storage application using cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. Since the GCD analysis of Ti3C2 MXene, a great specific capacitance (Csp) of 318F/g was attained with current density of 1 A/g and up to 90 % retentivity was attained after 7500 cycles. Besides, fabricated Ti3C2 MXene||Ti3C2-MXene symmetric supercapacitor device (SSD) has described the energy density (ED) of 27.78 Wh/kg at a power density (PD) of 400 W/kg and the capacitive retention existed attained 92.1 % after 7500 cycles with 5 A/g.