Galvanostatic Charge Discharge Research Articles

Synergistic effects of Ag nanoparticles in the rGO and Co3O4 based electrode materials for asymmetric supercapacitors

A systematic investigation of the composite electrode materials is vital in fabricating supercapacitors with high specific capacitance and good stability. The present work systematically studies the synergistic effects of Ag nanoparticles (AgNPs) on the electrochemical behaviour of rGO-based supercapacitor anode and Co3O4/rGO composite cathode. The Co3O4/(Ag/rGO) composite has been fabricated by hydrothermally growing Co3O4 nanoparticles over the previously prepared Ag/rGO support in the 70:30 ratio. The electrochemical performance of fabricated electrodes was evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) in 1 M KOH electrolyte. The Ag/rGO electrode having 15 - 20 % of AgNPs displays a specific capacitance of 553.6 F/g by CV (@10 mV/s) and 449.4 F/g by GCD (@0.35 A/g), which is 2.9 – 3.1 times higher than pristine rGO, when scanned in the range of – 1.0 V - 0.0 V (Vs. Ag/AgCl). The Co3O4/(Ag-20/rGO) composite electrode (in the ratio 70:30) possesses 244.9 F/g of specific capacitance (by GCD @3.8 A/g in the range of – 0.2 V - 0.5 V (Vs. Ag/AgCl)), which is 3.2 and 2.0 times higher than Co3O4 and Co3O4/rGO respectively. The Co3O4, Co3O4/rGO and Co3O4/(Ag/rGO) samples retained 67 % (at 3.8 A/g), 91 % (@1.4 A/g), and 82 % (@1.4 A/g) of specific capacitance after 2000 cycles. The asymmetric supercapacitor device in rGO||Co3O4/Ag/rGO configuration shows an initial specific capacitance of 438.0 F/g, energy and power densities of 38.9 Whkg‒1 and 640 Wkg‒1, respectively, at 2 A/g current density. The demonstrated boost in performance arises due to the presence of Ag nanoparticles leading to enhanced conductivity, catalyzing the pseudocapacitive reactions and preventing the graphene layers from aggregation by acting as spacers, spacers, thus making Ag/rGO and Co3O4/Ag/rGO as potential electrode materials for asymmetric supercapacitors.

Multiwalled-Carbon-Nanotube-Modified Li2ZnTi3O8 as Anode with Improved Cycling Stability and Rate Capability for Lithium-Ion Batteries

Due to its better electronic conductivity and larger lithium intercalation capacity, a multiwalled-carbon-nanotube (MWCNT)-modified Li2ZnTi3O8 (LZTO) has significant potential for use as an anode material for Li-ion batteries. The rapid and affordable ball-mill-aided solid state approach is used to synthesize LZTO with MWCNT-modified Li2ZnTi3O8 (LZTO@MWCNTs). Electrochemical performance tests of the anode material were carried out using cyclic voltammetry (CV), galvanostatic charge-discharge measurement, and electrochemical impedance spectroscopy (EIS). The CV experiments reveal that the LZTO@MWCNT electrode has a lower anodic and cathodic peak potential difference (0.184 V) than the LZTO electrode (0.211 V) and LZTO@MWCNT electrode has better electrochemical reversibility than that of pristine electrode after five cycles utilizing the same procedure. LZTO@ MWCNTs anode material has a higher charge-discharge capacity than LZTO anode material at 0.1–5 C rates. After 100 cycles, the initial discharge capacities of LZTO@MWCNT electrode are 227 and 142 mAh g−1 at the 1C–5C rate, respectively, whereas the initial discharge capacities of LZTO electrode are only144 and 28 mAh g−1 in the same condition. The charge transfer and SEI resistance of the LZTO anode are 19.31 and 62.74 ohms, respectively, after 30 cycles at 1C, according to the EIS data. Additionally, the values for the LZTO@MWCNTs anode are 7.93 and 12.06 ohms for charge transfer and SEI resistance, respectively.

Fabrication of Fe@Ni-orotate coordination polymer composite: iron doping provokes the colorimetric recognition efficiency for naproxen drug and energy storage magnitude

Coordination polymers have emerged as promising materials for various applications due to their unique properties and structural versatility. Making a composite with coordination polymers may broaden their applications. In this study, we developed Iron doped Nickel Coordination polymer Fe@Ni-CP from previously synthesized nickel orotate coordination polymer and explored its efficacy in sensing Naproxen (NPX) and also as an electrode material for energy storage devices. Photoluminescence sensing investigations exhibited a notable enhancement in NPX sensing efficiency, whereby the Fe@Ni-CP composite displayed a sensing efficiency of 94.05 %, surpassing the 6.42 % efficiency observed when utilizing the Ni-Orotate coordination polymer alone. Moreover, both materials showed significant differences in specific capacitance when tested as energy storage electrodes using Cyclic Voltammetry (CV) and Galvanostatic Charge Discharge (GCD). The Fe@Ni-CP has specific capacitance of 810.83 F/g, compared to 468.00 F/g for the Ni-CP. In Cyclic Voltammetry, Fe@Ni-CP retained 91.07 % specific capacitance after 4000 cycles. These findings underscore the potential of Fe@Ni-CP for multifunctional applications in sensing and energy storage.

Supercapacitive performance of solution processed free standing TiO2-rGO-TiO2 sandwich film electrodes

The development of flexibility and robustness in functional devices is an important feature for the next generation of devices for long operational periods. It infers applications for the compactness of batteries, bio- sensors, supercapacitors, wearable devices, and photovoltaics as well. Here, we report a two-step low-cost solution-based process to synthesize (a) free-standing films of graphene oxide (GO) and reduced graphene oxide (rGO) and (b) hybrid sandwich structures of titania and rGO by using simple chemical bath deposition. The microstructure and morphological study are carried out using X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Its electrochemical performance for supercapacitor electrodes were evaluated using three electrode cyclic voltammetry and galvanostatic charge-discharge system at different current density. In our experiment, graphene oxide is showing pseudo capacitance like behaviour, rGO and TiO2-rGO-TiO2 sandwich structure shows supercapacitor like behaviour. The value of capacitance for rGO is found 57.61 F/g. The sandwich structure with 0.17 M titania layers showing 121.92 F/g at 1.5 A/g current density with the highest power density observed 416 W/kg. Thus, this hybrid approach is not only having the potential to significantly boost the performance of future energy storage technologies but can also be used to develop cost-effective wearable electronics.

Polythiophene/nitrogen-doped reduced graphene oxide nanocomposite as a hybrid supercapacitor electrode

In this study polythiophene/nitrogen-doped reduced graphene oxide (Pth/n-rGO) was synthesized by in situ chemical polymerization. The correct synthesis of Pth/n-rGO nanocomposite was checked and confirmed through different spectral, elemental and morphological analysis. The supercapacitor performance of the Pth/n-rGO was higher than those of pure Pth and n-rGO in a neutral medium containing 1 M sodium sulfate. The highest energy density, specific capacitance, and power density values of 13.1 Wh kg−1, 455 F g−1, and 279 W kg−1 were achieved for the Pth/n-rGO nanocomposite. The Pth/n-rGO electrode also revealed commendable cyclic stability which it maintained 94% of its original specific capacitance and 125% coulombic efficiency during 1500 galvanostatic charge-discharge cycles. The superior charge-storage property of Pth/n-rGO is ascribed to the double-layer/pseudocapacitance charge storage synergistic effect. By considering the results of performance and stability for the Pth/n-rGO nanocomposite in this study, it could be good candidate for development of new supercapacitors electrode material.

Sr and Fe substituted LaCoO3 nano perovskites: Electrochemical energy storage and sensing applications

Perovskite-type LaCoO3 (LCO), La0.8Sr0.2CoO3 (LSCO), and La0.8Sr0.2Co0.9Fe0.1O3 (LSCFO) were prepared though a sol gel assisted hydrothermal method for supercapacitors and electrochemical sensors for heavy metal ions detection applications. Rhombohedral crystal structure was confirmed using experimental and DFT based computational XRD pattern. LCO, LSCO and LSCFO based modified carbon paste electrodes were prepared for cyclic voltammetry, electrochemical impedance spectra and galvanostatic charge discharge measurements. Among all electrodes, LSCFO results with 715.5 Fg−1 specific capacitance with 97 % retention after 1500 cycles. Cyclic voltammetry measurements for the sensing and detection of heavy metal ions (chromium and mercury) were carried out using all three electrodes and observed that LSCFO showed better response comparatively to that of other two electrodes, thus can be claimed as a potential mixed metal oxide nanomaterial for the fabrication of electrodes for storage of energy and sensor applications.

LiTaO3 mixing effects to suppress side reactions at the LiNi0.8Co0.1Mn0.1O2 cathode and Li5.3PS4.3Cl1.7 solid electrolyte of all-solid-state lithium batteries

Suppressing the side reactions at the solid electrolyte-electrode interface in all-solid-state battery (ASSB) is very important aspect of improving battery performance. Coating an electrochemically stable material on the surface of cathode has been used to suppress the side reactions occurring at interface between solid electrolyte and cathode. However, to achieve effective suppression, the thickness of the coating film must be thin and uniform. Moreover, an expensive ethoxide series typically must be used as a starting material. In this study, LiTaO3 coating material was simply mixed with the solid electrolyte to measure the effect of suppressing side reactions. To synthesize the solid electrolyte Li5.3PS4.3Cl1.7 and the mixing material LiTaO3, high-energy ball milling and wet milling methods were used, respectively. The structural characteristics of the prepared solid electrolytes were studied by powder X-ray diffraction. The LiTaO3 mixed solid electrolyte based ASSB showed a high discharge capacity of 177.3 mAh/g in the initial cycle, whereas the bare solid electrolyte (Li5.3PS4.3Cl1.7) based ASSB showed a discharge capacity of 159.1 mAh/g. To understand the side reactions, electrochemical impedance spectroscopy (EIS) analysis was performed after galvanostatic charge-discharge cycles. The EIS analysis confirmed that the side reaction between a solid electrolyte and a cathode was effectively suppressed in LiTaO3 mixed solid electrolyte based ASSBs.

Thiourea modulated supercapacitive behavior of reduced graphene oxide

In this report, we investigated the role of the concentration of nitrogen and sulfur containing thiourea in modulating the electrochemical properties of reduced Graphene Oxide (rGO) by controlling the percentage of heteroatoms on the rGO surface. The synthesis route involved the preparation of Graphene Oxide (GO) using an improved method of synthesis in an economical way by reducing the volume of concentrated acids used. Furthermore, GO is reduced by using different mass proportions of thiourea via a simple reflux method. Characterization of the rGO samples by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDAX) and elemental analysis through CHNS analyzer exhibited successful doping and impact of nitrogen and sulfur atoms on the graphene framework. The comparative electrochemical performance from Cyclic Voltammograms (CV), Galvanostatic Charge Discharge (GCD) profiles and Electrochemical Impedance Spectroscopy (EIS) measurements on the various rGO samples revealed the superiority of 1:8rGO having 15.190 wt% of nitrogen and 26.849 wt% of sulfur and S/N ratio of 1.768, in delivering highest specific capacitance of 465.21 F·g−1 at 1 mV·s−1 scan rate with a remarkable cyclic stability exhibiting a capacitive retention of 119 % and offering lowest charge transfer resistance and diffusion resistance. The study also demonstrated detrimental effect of excess thiourea on electrochemical properties of rGO. This work suggests an effective and simple approach for optimizing the nitrogen and sulfur content in rGO to enhance its electronic properties using thiourea.

The effect of copper doping in α-MnO2 as cathode material for aqueous Zinc-ion batteries

Copper-doped Manganese Dioxide has been synthesised through a simple hydrothermal method at different doping levels. The synthesised materials have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) to determine the composition, structure, and morphology. All the Cu doped MnO2 are found to be single phased. Their electrochemical properties as cathode for Zinc-ion batteries are studied by cyclic voltammetry (CV), galvano-static charge / discharge (GCD) and electrochemical impedance spectroscopy (EIS), using 3 M ZnSO4 + 0.3 MnSO4 solution as the electrolyte. 3.8% Cu doped MnO2 has shown the highest initial capacity of 379.5 mAh g−1 at 0.02 A·g−1, and 304.4 mA h g−1 at 0.5 A g−1, but experienced fast fading with a poor capacity retention of 56.8% after 100 cycles. 7.4% Cu doping gives lower capacity, while 5.9% doping shows a higher discharging capacity (320.0 mAh·g−1 at 0.02 A·g−1 and 269.3 mAh·g−1 at 0.5 A·g−1) and improved stability (85.8% capacity retention after 100 cycles), better than non-doped MnO2 electrode (284.4 mAh g−1 at 0.02 A g−1 and 252.1 mAh·g−1 at 0.5 A g−1, capacity retention 76.7%). The samples show satisfactory capacity and rate capability while the cycling stability is not ideal, which may relate to the needle like morphology and nanoscale particle size. CV tests revealed that the electrochemical process is mainly diffusion controlled. The zinc ion diffusion coefficient is tested to be in the range of 10−12 cm2·s−1 from both CV and EIS tests and showed the same trend in their electrochemical capacity. Doping of Copper in MnO2 reduced the polarization on electrode, improved the electrochemical reversibility, as evidenced by the reduction of the redox peak potential difference from 0.31 to 0.24 V at 1.1 mV·s−1, and from 0.45 V to 0.31 V at 5 mV·s−1. Whilst the cell resistance of non-doped MnO2 increased from 1.78 Ω to 7.39 Ω after cycling, the cell resistances of all Cu-doped cathodes reduced, indicating improved electronic conductivities after cycling. These results indicate that Cu-doping is effective to increase the conductivity of the materials, reduce the polarization during charge and discharge, and improve the cycling stability of MnO2 cathode.

Development of single-atom Ru and N, S-Co-doped carbon catalyst for enhanced cycling stability of lithium-oxygen batteries

Li-oxygen (Li-O2) battery is a novel energy storage equipment. However, its poor reaction reversibility relating to the insoluble lithium peroxide (Li2O2) generated during the discharge process, limits its application and development for large scale use. Therefore, the design and synthesis of effective catalysts which can efficiently catalyze the production and decomposition of Li2O2 and exclude the generation of side-products has become the primary task to develop Li-O2 batteries. Herein, a new type of electrocatalyst based on single-atom Ru and N, S-co-doped carbon materials (Ru/CNS/CNT) is introduced to reduce the overpotential of the battery reaction and accelerate the formation and decomposition of Li2O2. Galvanostatic charge-discharge tests were performed on the Li-oxygen (Li-O2) battery with Ru/CNS/CNT as the cathode catalyst material. With a limited specific capacity of 1000 mA h g−1, the battery can stably cycle for 79 cycles at a current density of 200 mA g−1. Furthermore, the existence of the single atom of Ru was demonstrated according to the characterization of HAADF-STEM. The experimental results showed that composite material Ru/CNS/CNT can accelerate the formation and decomposition of lithium peroxide (Li2O2), thereby greatly improving the cycling stability of the battery.

Enhanced electrochemical performance of the electrodeposited nickel sulfide on ZIF-67@RGO composite for supercapacitor applications

Zeolitic imidazolate frameworks (ZIF), as a form of metal-organic frameworks (MOFs), are promising materials used as electrodes for energy storage devices. Their high electrical conductivity results from numerous conjugated systems and the collaboration between the ligand and cobalt significantly enhances their redox capacity. The bulk electrical conductivity and specific capacitance of ZIF materials can be enhanced by the incorporation of rGO and metal sulfide, respectively. Herein, ZIF-67@RGO nanocomposite was fabricated and then modified with 20.0 wt% Ni nanoparticles followed by co-electrodeposition of sulfur as a novel electrocatalyst. The prepared composites were analyzed using various techniques, including FT-IR, XRD, XPS, SEM, and EDX mapping. The electrochemical performance of the prepared composite electrodes was measured using different techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The S-Ni/ZIF-67@RGO electrode displayed excellent electrochemical behaviour which is evident in the high value of the specific capacitance of 1142.3 F g−1 at a current density of 1 A g−1. On the other hand, an asymmetric supercapacitor (ASC) was assembled by employing the unique composite material in conjunction with conductive carbon black. The power and energy densities of the ASC device were 774 W kg−1 and 88.2 Wh kg−1, respectively. The capacitance of S-Ni/ZIF-67-RGO is retained at 90.8% even after 3000 cycles, suggesting remarkable cycle stability. This study expands the application scope of ZIF-67 and introduces a new method for fabricating novel electrode materials.

Electrochemical performance of chemically treated pyrolytic carbon black from waste car tyres

Pyrolytic carbon black (CBp) is a solid by-product of tyre pyrolysis that contains various contaminants from the tyre additives. These contaminants limit the use of CBp as a carbon source for energy storage applications such as supercapacitors. This study aims to improve the physicochemical, morphological, and electrochemical properties of CBp by applying different chemical treatments and activation methods. The chemical treatments include acid (HCl), base (NaOH), acid-base (HCl/NaOH), and desulphurization (NaOH in xylene) processes to remove impurities such as sulphur, zinc, and silicon. The treated CBp samples are then activated by KOH impregnation technique to increase the surface area and porosity. The characterizations of the treated CBp samples are performed using Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), and Brunner Emmett Teller (BET). The electrochemical performance of the treated CBp samples are evaluated using galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that the chemical treatments significantly reduce the impurity levels and enhance the electrochemical performance of CBp. The desulphurized CBp sample exhibits the highest specific capacitance of 218 F/g among the treated CBp samples. The findings of this study suggest that CBp can be effectively utilized as a potential carbon source for supercapacitor electrodes by applying suitable chemical treatments and activation methods. This will create a circular economy to valorize CBp.

Activated Carbon Derived from Cucumber Peel for Use as a Supercapacitor Electrode Material.

Biowaste conversion into activated carbon is a sustainable and inexpensive approach that relieves the pressure on its disposal. Here, we prepared micro-mesoporous activated carbons (ACs) from cucumber peels through carbonization at 600 °C followed by thermal activation at different temperatures. The ACs were tested as supercapacitors for the first time. The carbon activated at 800 °C (ACP-800) showed a high specific capacitance value of 300 F/g at a scan rate of 5 mV/s in the cyclic voltammetry and 331 F/g at the current density of 0.1 A/g in the galvanostatic charge-discharge analysis. At the current density of 1 A/g, the specific discharge capacitance was 286 F/g and retained 100% capacity after 2000 cycles. Their properties were analyzed by scanning electron microscopy, energy-dispersive X-ray analysis, porosity, thermal analysis, and Fourier-transform infrared spectroscopy. The specific surface area of this sample was calculated to be 2333 m2 g-1 using the Brunauer-Emmett-Teller method. The excellent performance of ACP-800 is mainly attributed to its hierarchical porosity, as the mesopores provide connectivity between the micropores and improve the capacitive performance. These electrochemical properties enable this carbon material prepared from cucumber peels to be a potential source for supercapacitor materials.

Dibutyl benzotriazolium tetrafluoroborate doped PANI as an electrode material for energy storage

This work is on the reporting of the synthesis of 1,3-dibutyl-1,2,3-benzotriazolium tetrafluoroborate-doped polyaniline through interfacial polymerization and its material characterizations through FT-IR, XRD, EDS, FESEM, XPS, BET, and TGA and electrochemical property evaluation through CV, EIS, and GCD. The electrode was tested in an ionic liquid electrolyte solution with a 3-electrode setup, which gave an effective potential window from −1.5 to 1.0 V. PANI-DIBUTBTBF4 electrodes were tested on benzotriazolium tetrafluoroborate gel polymer electrolyte using poly(vinylidenefluoride-co-hexafluoropropylene) as host polymer for supercapacitor application through evaluating the electrochemical properties of the fabricated prototype with CV, EIS, and GCD. The SC prototype showed an efficient electrochemical window of 3.5 V. And at 0–3.5 V, it shows a high specific capacitance of 1417.88 F g−1 at a scan rate of 2 mV s−1, and from the galvanostatic charge discharge cycle at a current density of 0.32 A g−1, an energy density of 7.11 mW h g−1 and a power density of 555.06 mW g−1 were observed. The prototype retains a capacitance of 89 % even after 3000 cycles. A single swagelok cell charged at 2 V for 20 min was able to light a red (1.6 V, 20 mA) LED brightly for 5 min, which demonstrated its practical applicability.

Supercapacitive performance of 3D-cobalt oxide (Co3O4) nanowires grown onto anodized stainless-steel substrate: Effect of anodization time

3D-Co3O4 nanowires were grown on anodized stainless steel (SSA) using a simple hydrothermal technique, with SSA as a cost-effective porous substrate. The originality of this work is to enhance surface activity and material adhesion by anodizing stainless steel (SS). After growth, the nanowires were thermally treated at 400 °C for 2 h. By varying the SS anodization time from 0 to 900s, changes in the structural, morphological, and electrochemical properties of Co3O4 were observed. XRD analysis confirmed the polycrystalline nature of Co3O4 with a face-centered cubic phase. SEM imaging showed noticeable changes in density and surface roughness. Supercapacitive properties were evaluated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) techniques, with SSANWs-300 exhibiting the highest specific capacitance of 529 Fg-1. Dunn's method was used to analyze the contribution of capacitive and diffusive mechanisms to charge storage. EIS results indicated excellent electronic conductivity. The study suggests that SSANWs-300 holds promise for energy storage applications.

Facile synthesis of cobalt-nickel oxide nanocomposites for trifunctional application towards antioxidant, anticancer and electrochemical performance

Transition metallic mixed oxides have received a lot of curiosity due to their exceptional electrochemical performance and incredibly low cost for hybrid supercapacitors. Herein, we report a facile synthetic approach of cobalt nickel oxide (CNC) composites from Carica papaya leaf extract. The synthesized mixed oxide composite was analyzed by various spectroscopic techniques (IR, UV–Vis, Powder XRD, SEM-EDAX, TEM and XPS). The electrochemical behavior of CNC was investigated by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) method in 2 M KOH solution. The composites exhibit specific capacitance of 289.28 F g−1 at 1 A g−1 demonstrating improved charge storage. The electrode retains 81 % of its specific capacitance from the initial value after repeated charge–discharge processes for 2000 cycles. In addition to the electrochemical studies, biological activities such as anti-oxidant and anti-cancer activities of the CNC were examined. The radical scavenging activity of CNC was assessed with different radicals such as DPPH•, ABTS+., NO–, OH•, O2– and the acquired results showed that the composites possessed substantial activity. Anticancer activity of CNC was studied against HepG2 and MM2 cancer cells and the CNC possessed significant activity with the IC50 value of 45.8 and 38.3 µg/ml respectively compared with the standard drug cisplatin. Further apoptogenic nature of the CNC was confirmed with DAPI staining assay.

Advanced composite material for high-performance supercapacitors: integrating graphene oxide and barium chromate

Graphene oxide-based Barium chromate (BaCr2O4@GO) composites were successfully synthesized through sonication assisted by a hydrothermal process designed for supercapacitor applications. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and morphological analyses were employed to characterize the nanostructured composites. The XRD and FTIR results reveal that the GO nanoparticles are arranged in a honeycomb-like configuration. Moreover, the TEM images reveal the presence of cauliflower-like structures in the morphology of the composites, which is attributed to the effective intercalation of GO during the thermal reduction process. The electrochemical properties of the nanocomposite were compared to those reported in previous studies on metal chromite materials aimed at enhancing supercapacity applications. The analysis of Galvanostatic Charge–Discharge (GCD) data indicates a significant increase in power density values from 292 W kg−1 to 495.5 W kg−1 for the Nanocomposites. The ability to achieve a balance between enhanced power density and efficient ion transport positions the -nanocomposites as a valuable candidate for advancing the performance of supercapacitors.

Polycrystalline phases engineered in-situ in polyaniline-graphene composite evoluting an exceptional stability and high charge storage capacity: An EIS investigative approach to evaluate material's stability

Development of electroactive materials exhibiting high performance with superior stability is crucial in the field of supercapacitors and battery research. We report on synthesis of highly stable composite of semi-polycrystalline polyaniline and graphene (SPani-graphene) and its application in supercapacitor electrodes. The electrochemical behavior and device performance of the electrodes were investigated through cyclic voltammetry (CV), galvanostatic charge-discharge GCD) and electrochemical impedance spectroscopy (EIS) in a 3-electrode and a 2-electrode (device) cell configurations, repectively. The cell specific capacitance (Cell Csp) achieved from the 2-electrode symmetric cell configuration was 525.5 F g−1 at 0.1 A g−1 using polymer gel electrolyte (PGE). The PGE in this work is xanthan gum jellied in 1 M aq. Na2SO4. The maximum energy density and power density achieved from the device was 46.7 Wh kg−1 and 16.16 kW kg−1, respectively, at 0.4 A g−1. Furthermore, the device exhibits an excellent retention of cell specific capacitance and coulombic efficiency of 97 % and 94 %, respectively, over 10,000 continuous GCD cycles, indicating an excellent rate capability as well as a promising power management. To investigate the material's electrochemical durability, a detailed EIS study has been carried out using both, 3-electrode, and 2-electrode cell configurations, before and after long cycling test (over 10,000 continuous GCD cycles). Our thorough experimentation delivers satisfactory results and has been explained in detail in the manuscript. Hereby, we propose that the EIS technique can be adopted for investigating materials' electrochemical stability, in addition to long CV and GCD cycles in the field of supercapacitors and battery research.

Ternary nanocomposite of RAFT‐polymerized DMAEMA‐functionalized graphene oxide, manganese dioxide and polyaniline as active electrode material for supercapacitor

AbstractGraphene and its derivatives are promising energy storage devices due to their high specific surface area, chemical and thermal durability and high charge transfer power. Still, their stacking and aggregate behavior can limit their practical application. To address this issue, reversible addition–fragmentation chain‐transfer (RAFT) polymerization as controlled radical polymerization was applied to functionalize the surface of graphene oxide with poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) via the ‘grafting from’ method. This strategy enhances the distance between graphene sheets by occupying physical volume while improving effective charge transfer through tertiary amine groups participating in the doping process. X‐ray diffraction was used to determine interlayer spacing after polymer grafting, which increased from 0.28 to 1.71 nm after polymer grafting. The hybridization of materials with diverse properties was used to enhance charge transfer capability for supercapacitor applications. PDMAEMA‐functionalized graphene oxide, nano‐manganese dioxide and polyaniline were combined to create a successful nanocomposite as electrode active material. The morphological structure and chemical composition of the synthesized nanocomposite were analyzed, and its electrochemical performance was evaluated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The nanocomposite exhibited a maximum specific capacitance, energy density and power density of 364.72 F g−1 (at a scan rate of 50 mV s−1), 239.08 Wh kg−1 and 678.34 W kg−1, respectively. The final nanocomposite's energy storage capacity significantly increased compared to the individual components due to hybridization's synergistic impact, reducing charge transfer resistance. © 2024 Society of Industrial Chemistry.

Exploring the synergistic power: Green synthesis, comprehensive characterization, and unveiling the energy generation and storage aptitude of phyto‐mediated Sb2O3‐ZrO2 nanocomposite

AbstractBackgroundResearchers are keen to reduce the over potential value through fabrication of electrocatalyst consisted of environmentally benign and inexpensive material. Supercapacitors on the other hand have gained immense attention in recent years as an energy storage device due to the high power density potential of these devices as compared to conventional batteries based storage system.AimThe research aims to synthesize nanoscale transition metal oxides (TMO) through green route. TMO based nanomaterials have vast role in energy related applications.Materials & methodsIn this study, organic compounds of A. Viridis were used as reducing and stabilizing agents in the synthesis of binary nanocomposite Sb2O3–ZrO2. The synthesized nanocomposite was characterized using x‐ray diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, field emission scanning electron microscopy and energy dispersive spectroscopy. The electrode material was analyzed for supercapacitor potential using cyclic voltammetry and galvanostatic charge discharge techniques. HER and OER studies were also conducted using electrochemical impedance spectroscopy and linear sweep voltammetry. The synthesized material was also tested for stability.Results & discussionThe crystal size was 15.9 nm. Optical band gap of 2.55 eV was obtained through Tauc plot. The capacitance value of 339.8 F/g at 2 mV/s and the specific capacitance of 100.6 F/g was obtained at 1 A/g. The overpotential value of 201 mV and Tafel value of 121 mV/dec was recorded for the HER, whereas the lower Tafel value of 106 mV/dec and over potential value of 383 mV was determined for OER. Electrode showed promising stability up to various cycles in case of both applications.ConclusionThe obtained results revealed the promising performance with excellent stability of fabricated electrode for super capacitor as well as water splitting studies.