Electrodes For Energy Storage Research Articles

Advanced electrochemical performance of N-Ti3C2/MnO2 MXene as a promising electrode for energy storage

Advanced electrochemical performance of N-Ti3C2/MnO2 MXene as a promising electrode for energy storage

Interconnecting EDOT-Based Polymers with Native Lignin toward Enhanced Charge Storage in Conductive Wood.

The 3D micro- and nanostructure of wood has extensively been employed as a template for cost-effective and renewable electronic technologies. However, other electroactive components, in particular native lignin, have been overlooked due to the absence of an approach that allows access of the lignin through the cell wall. In this study, we introduce an approach that focuses on establishing conjugated-polymer-based electrical connections at various length scales within the wood structure, aiming to leverage the charge storage capacity of native lignin in wood-based energy storage electrodes. We demonstrate that poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) PEDOT/PSS, integrated within the cell wall lumen, can be interfaced with native lignin through the wood cell wall through in situ polymerization of a water-soluble S-EDOT monomer. This approach increases the capacitance of the conductive wood to 315 mF cm-2 at a scan rate of 5 mV s-1, which is seven and, respectively, two times higher compared to the capacitance of conductive wood made with the single components PEDOT/PSS or S-PEDOT. Moreover, we show that the capacitance is contributed by both the electroactive polymers and native lignin, with native lignin accounting for over 70% of the total charge storage capacity. We show that accessing native lignin through in situ creation of electrical interconnections within the wood structure offers a pathway toward sustainable, wood-based electrodes with improved charge-storage capacity for applications in electronics and energy storage.

Pitch-derived Multifunctional Carbon and Bimetallic Sulfide Composite Electrodes for Aqueous Energy Storage

With the rapid development of society, people's requirements for the ecological environment have become increasingly stringent. Coal tar pitch is a by-product of coal processing, which has low value and serious pollution. Under the circumstance, coal tar pitch-derived carbon materials (CTPC) was successfully prepared with the interconnected three-dimensional porous structure, and then NiCo2S4/CTPC composite materials were obtained. CTPC exhibits high conductivity (15.59 S m-1), large specific surface area (614.9 m2 g-1), and rich porous structure of connected carbon nanosheets. Among composite materials with different CTPC contents, the NiCo2S4/CTPC material exhibits the highest specific capacities under the same conditions. Notably, the capacity of NiCo2S4/CTPC is up to 689.6F·g-1 at 1A·g-1. The assembled asymmetrical supercapacitor (NiCo2S4/CTPC//CTPC) exhibits a long cyclic stability of 4000 cycles at 4A·g-1. When the power density is 3616.44Wkg-1, the energy density is as high as 22Whkg-1. Meanwhile, NiCo2S4/CTPC was used as cathode material to assemble an alkaline battery (NiCo2S4/CTPC//Bi2O3) and then its electrochemical properties were systematically analyzed.

Enhanced efficiency of the electrode by doping of neodymium on SmFeO3 for the application of supercapacitor

In response to growing demand for the renewable energy generating and storage systems, scientists are trying to synthesized electrode material with exceptional performance. Their primary objective was to develop portable intelligent technology gadgets that could guarantee global energy security. In the reported article, the SmFeO3 with Nd-doped material was manufactured by cost-effective hydrothermal method for the application of a supercapacitor. The results demonstrate that the existence of larger surface area improves electrical conduction and improves the electrons and ions pathway, resulting in a rapid charge storage device and greatly enhancing the electrical performance. The pristine SmFeO3 electrode achieved capacitance of 746.3 F g−1, and the Nd-doped SmFeO3 electrode achieved a heightened capacitance of 1455.9 F g−1 at 1 A g−1. Further, the pristine SmFeO3 electrode demonstrated low cyclic retention after the 5000th charging/discharging cycles, while the Nd-doped SmFeO3 electrode demonstrated significant cyclic retention. In addition, the material fabricated attained a significant capacitance of 923.9 F g−1 at 10 mV s−1 during cyclic voltammetry measurements. The exceptional performance of dopant materials suggests their promising conductivity and quick electron/ion transport factors in its exceptional performance made it an excellent electrode for energy storage devices as well as suitability for future-generation energy conversion by surpassing the reliance on perovskite-type structural materials.

Synthesis of urchin-like MnCo2O4 nanospheres as electrode material for supercapacitors

The morphology of MnCo2O4 has a significant effect on the electrochemical performance. In this paper, urchin-like MnCo2O4 nanospheres was successfully fabricated by a simple hydrothermal process and post-annealing treatment. The effects of addition of surfactant (Hexadecy ltrimethyl ammonium bromide) on the crystal structure, surface morphology and electrochemical performance of MnCo2O4 have been investigated. The results show that all the synthesized manganese cobalt oxides are composed of cubic spinel MnCo2O4. The addition of surfactant leads to the change of the morphology of MnCo2O4 from nanoarray to urchin-like nanospheres and increases the specific surface area, which is beneficial to improve the electrochemical performance of the MnCo2O4 electrode. The electrochemical test reveals that the urchin-like MnCo2O4 nanospheres delivered a high specific capacity of 2019 F/g at a 1 A/g and 1144 F/g at 5 A/g, respectively. The specific capacity of MnCo2O4 electrode reaches 512 F/g at 10 A/g and retains 96 % of the initial capacity after 2000 cycles at 10 A/g, which maintains an extraordinary cycling performance. In addition, an asymmetric supercapacitor (MnCo2O4//AC) with urchin-like MnCo2O4 nanospheres as a cathode and activated carbon (AC) as an anode was also assembled. Impressively, the assembled MnCo2O4//AC asymmetric supercapacitor exhibits a high energy density of 69 Wh/kg at a power density of 793 W/kg. The above research shows that the urchin-like MnCo2O4 nanospheres synthesized by adding surfactants are expected to be excellent high-performance energy storage electrode materials, which provides a new strategy for the synthesis of high-capacity nanoelectrode materials.

ZnMnCoS/rGO nanocomposite for an effective bifunctional electrode for overall water splitting and supercapacitor applications

Abstract Future energy storage and energy conversion devices will benefit from the development of active electrode materials that serve as both an electrocatalysts and an energy storage device. Recently, mixed metal sulfides are cheaper and have improved electrical and electrochemical performance than their oxide/hydroxide similarly has garnered a lot of interest for use in energy storage and electro catalysis applications. In this, mixed metal sulfides, as zinc manganese cobalt sulfide (ZMCS) and reduced graphene oxide composite zinc manganese cobalt sulfide (rZMCS) were successfully synthesized via hydrothermal route for overall water splitting and supercapacitor. The prepared materials are characterized through x-ray diffraction, x-ray photoelectron spectroscopy, Field emission scanning electron microscope, transmission electron microscope with elemental mapping and Brunauer–Emmett–Teller analysis. The ZMCS and rZMCS electrodes exhibit an over-potential of 258 and 170 mV for HER and 302 and 230 mV for OER at a density of current is 10 mA cm2 in 3 M KOH. Overall water splitting is carried out for rZMCS electrodes and it shows the long-term stability of 15 hrs. The specific capacitances of ZMCS and rZMCS electrodes are 1065 F g1 and 1167 F g1 at 1 A g1. The obtained electrode could maintain 96 % and 98 % until 5000 cycles. Asymmetric supercapacitor device rZMCS//rGO delivers a total amount of energy and power is 47.6 Wh kg1 and 925 W kg1 with could maintain 86 % upto 10000 cycles. The outcomes draw attention to the produced electrode able to be practical as a multifunctional electrode for energy storage and conversion devices.

Electrolyte optimization for enhanced electrode performance in aqueous Zn//WO3 mixed-ion battery

Aqueous electrochemical energy storage has emerged as a low-cost and sustainable technology. Among the diverse array of electrode materials, tungsten trioxide (WO3) holds promise due to its unique electrochemical properties and environmental compatibility. In this study, we investigate the potential of WO3 for aqueous energy storage applications, focusing on its performance in different electrolytes, namely, 0.5 M Na2SO4, 1.0 M ZnSO4, and 0.5 M Al2(SO4)3. Electrochemical measurements and density functional theory (DFT) calculations indicate that the charge density of electrolyte cation influences the WO3 electrode performance. A superior performance is observed in the Al2(SO4)3 electrolyte due to the high charge density of Al3+ ions. We further investigate WO3 as a cathode in the full-cell configuration using Zn metal as an anode and a mixed solution of 1.0 M ZnSO4 and 0.5 M Al2(SO4)3 as an electrolyte. The mixed-ion Zn//WO3 battery exhibits high specific energy and good cycling stability, highlighting the feasibility of WO3 as an electrode for practical aqueous energy storage. Overall, this study provides insights into the electrochemical behavior of WO3 in aqueous environments and underscores its potential for advancing sustainable energy solutions.

Yolk-shell structured FeS0.5Se0.5@N-doped mesoporous carbon composite as high-performance lithium-ion battery anodes

Transition metal selenides/sulfides are drawing growing attention as promising electrode material for lithium-ion batteries owing to their larger layer spacing and weaker ionic bond compared to transition metal oxides, which are conducive to the intercalation/de-intercalation of Li ions. However, the intrinsic low conductivity and large volume expansion remain a major obstacle for their practical applications. In this work, with the prediction help of the theory model, we design a yolk-shell structure of single-phase ternary FeS0.5Se0.5 and nitrogen-doped mesopore carbon (YS-FeS0.5Se0.5@NMC) via an interfacial co-assembly, followed by one-step selenization and vulcanization. In the composite, single-phase ternary FeS0.5Se0.5 yolk provides more active sites and faster ion/electron transport dynamics than binary Fe2O3, while N-doped mesoporous carbon shell effectively alleviates the large volume expansion of FeS0.5Se0.5, as revealed by in-situ Raman analysis and TEM observation. Meanwhile, the spatial confinement of outer carbon shell also ensures the mechanical stability of the electrode during cycles. These merits endow the YS-FeS0.5Se0.5@NMC anode with a high reversible capacity of 1417mA h/g at 200mA h/g after 120 cycles, and an exceptional rate capability. This work offers an inspired approach for achieving high-performance energy storage electrode materials

Enhanced solid-state reaction synthesis of CdO, SnO, and CdO0·2/SnO0.2 hetero-junction electrode for high-performance energy storage

This study unveils a superior method for energy storage synthesis, employing CdO, SnO, and CdO0·2/SnO0.2 hetero-junction electrodes through enhanced solid-state reaction. The CdO and SnO electrodes with a specific capacitance of 266.66, 191.66, 166.66 ​F/g and 138.88, 122.22, and 115.07 ​F/g. The CdO0·2/SnO0.2 hetero-junction nanoparticles with a specific capacitance of 370.37, 222.22, 158.73 ​F/g. The charge storage capacity of CdO0·2/SnO0.2 hetero-junction nanoparticle electrodes is outstanding, making them highly beneficial for energy storage and supercapacitor applications. The XRD patterns obtained from the synthesized CdO0·2/SnO0.2 hetero-junction nanoparticles exhibit distinct diffraction peaks, showing a cubic crystal structure. These diffraction peaks, at 2θ values of 27.111°, 34.189°, 38.682°, 52.635°, 55.793o, 62.779o, 66.676o, and 79.496° can be attributed to the (111), (200), (211), (212), (220), (300), (22), and (311) diffraction planes of CdO0·2/SnO0.2 hetero-junction nanoparticles. The observation of a grain-like shape in the CdO0·2/SnO0.2 hetero-junction nanoparticles structure is attributed to CdO, which serves as a confirmation of the formation of a hetero-junction. The energy bandgap of CdO, SnO, and CdO0·2/SnO0.2 hetero-junction nanoparticles material are 2.50, 3.50, and 3.35 ​eV respectively.

Enhanced Methanol Electrooxidation and Supercapacitive Performance via Compositional Engineering of Colloidal Ni-Co Alloying Nanoparticles.

Among renewable energy technologies, particular attention is paid to electrochemically transforming methanol into valuable formate and storing energy into supercapacitors. In this study, we detailed a simple colloidal-based protocol for synthesizing a series of alloy nanoparticles with tuned Ni/Co atomic ratios, thereby optimizing their electrochemical performance. With the addition of 1 M methanol in 1 M KOH, the optimized composition was able to electrochemically produce formate at 0.149 mmol cm-2 h-1 with a Faradaic efficiency up to 95.1% at 0.6 V versus Hg/HgO within a 22-hour testing period. In 1 M KOH solution without methanol, the supercapacitive performance was achieved at a specific capacitance of over 1500 F g-1, and outstanding cycling stability with only approximately 20% decay after continuous 10000 charging-discharging cycles. These results underscore that the prepared Ni-Co alloy nanoparticles serve as multi-functional electrodes for electrochemical energy conversion and storage, particularly in the MOR and supercapacitors applications.

Modification Strategies and Prospects for Enhancing the Stability of Black Phosphorus.

Black phosphorus is a two-dimensional layer material with promising applications due to its many excellent physicochemical properties, including high carrier mobility, ambipolar field effect and unusual in-plane anisotropy. Currently, BP has been widely used in biomedical engineering, photocatalysis, semiconductor devices, and energy storage electrode materials. However, the unique structure of BP makes it highly chemically active, leading to its easy oxidation and degradation in air, which limits its practical applications. Recently, researchers have proposed a number of initiatives that can address the environmental instability of BP, and the application of these physical and chemical passivation techniques can effectively enhance the environmental stability of BP, including four modification methods: covalent functionalization, non-covalent functionalization, surface coordination, physical encapsulation and edge passivation. This review highlights the mechanisms of the above modification techniques in addressing the severe instability of BP in different application scenarios, as well as the advantages and disadvantages of each method. This review can provide guidance for more researchers in studying the marvellous properties of BP and accelerate the practical application of BP in different fields.

Co3O4/rGO based nanocomposite architectures as electrodes for advanced energy storage and their pseudocapacitive attributes

In response to escalating global challenges in energy storage, this study embarked on captivating exploration of electrochemically proficient Co3O4 composites, seamlessly integrated with varying concentrations of reduced graphene oxide (5 %, 10 %, and 15 %). Using a single-step hydrothermal method, Co3O4 was synthesized, followed by a solvothermal process to produce Co3O4/rGO composites. These composites were then applied to Nickel Foam to fabricate electrodes. The structural properties of these novel Co3O4/rGO/NF electrodes were analyzed using X-ray Diffractometer, which confirmed the distinctive crystalline structure of Co3O4 and indicated no phase transformation after the introduction of rGO. Morphological analysis through a Field Emission Electron Microscope and Transmission Electron Microscope revealed layered structures and increasing porosity correlated with higher rGO concentrations. Electrochemical performance was rigorously tested through cyclic voltammetry, which verified the pseudocapacitive attributes of the samples. Additionally, galvanostatic charge-discharge studies highlighted that the electrode containing 15 % rGO demonstrated highest (Cs = 1360 Fg−1) at 1.7 Ag−1, with 86 % of cyclic retention after 5000 cycles. Electrochemical impedance spectroscopy further demonstrated superior conductivity, underscoring the potential of these electrodes'for supercapacitor applications.

Low temperature electrochemical properties and energy storage mechanisms of gently modified porous carbon fabric-based flexible supercapacitors

The development of a low-temperature-resistant flexible energy storage device represents a significant challenge that requires urgent attention. In this study, the electrochemical properties of modified carbon fabric (MCF) were significantly improved by applying mild surface modification techniques. The resulting MCF-based symmetrical supercapacitors (SSCs) were assembled using conventional sulfuric acid as the electrolyte and demonstrated remarkable resilience to extremely low temperatures of −60 °C while exhibiting excellent electrochemical performance. Specifically, the optimal area capacitance relative to 25 °C was 2831 mF cm−2, and the areal capacitance at 0, −20, −40, and −60 °C was maintained at 86.63 %, 83.22 %, 79.87 %, and 70.04 %, respectively, exhibiting outstanding low-temperature resistance. The capacitance retention rates of the lifetime tests at different temperatures were found to be above 90 %, further supporting the excellent cycling stability of the SSCs. In addition, the factors contributing to the differences in electrochemical performance at different temperatures were analyzed mechanistically by combining the experimental results and molecular dynamics (MD) simulations. Furthermore, the areal capacitance of the assembled flexible SSCs was found to be reversibly retained even after continuous temperature tests between 25 and −60 °C. Moreover, even at −60 °C, the areal capacitance was maintained by 71.42 % at 25 °C, and the capacitance retention was up to 90.32 % after undergoing 10,000 cycles. This research indicates that MCF electrodes have the potential to be used as electrodes for flexible energy storage devices that are low-temperature resistant, stable and low-cost.

Nanocomposite Material Sb2S3:SnS:MnS2 its Fabrication and Utilization as Efficient Electrode for Energy Storage in Supercapacitor

AbstractThe nanocomposite material Sb2S3: SnS:MnS2 was fabricated by single precursor technique by using dithio‐carbamate ligand as Sb2S3:SnS:MnS2 (DDTC) complex. An internal and external look at the anatomy and activity of the substance was obtained by using a variety of analytical techniques like XRD, FTIR, UV‐Vis and SEM. Additionally, various electro‐analytical tools like LSV, CV, GCD and EIS were applied to confirm material's rich electro‐active capability for photoactive electrode. XRD revealed its average crystallite size of 12.33 nm with 82.8 % crystallinity. Optical characteristics represented describe effective semiconducting nature of nanomaterials with optimum band gap of 2.65 eV. By using electrochemical processes, LSV and CV demonstrated fertile opto‐electrical nature of Sb2S3: SnS: MnS2 (DDTC) material with specific capacitance, Csp, of 1080 F/g at scan rate of 2 mV/s. With a high specific power density of 2656 W/kg, the GCD technique attempted to validate the nature of the material as an electrode with a good charge‐discharge mechanism. In EIS, low series resistance, Rs=0.73 Ω, was observed to be very beneficial argument in validating the nanocomposite synthesized in this research project as effective and low‐cost material which can be applied in different energy producing and storing devices like solar system and super‐capacitors etc.

Rapid and controllable microwave synthesis of nickel cobalt sulfide electrodes for high-performance asymmetric supercapacitors

The efficient and controllable synthesis method of high-performance energy storage electrode materials is crucial for advancing the development of energy storage technologies. Herein, by leveraging microwave heating technology in the sulfidation of nickel cobalt MOF, we effectively enhanced the efficiency of the synthesis process. Notably, sulfidation time emerged as a pivotal factor in tuning the crystalline phase structure and conductive properties of the material, leading to the successful development of NCS2 electrode material with a unique structure through optimized sulfidation conditions. Electrochemical performance tests of the NCS2 material revealed exceptional results; it exhibited a specific capacity of 1311 Fg[Formula: see text] at a current density of 1 Ag[Formula: see text] and retained 73.4% of its initial capacity when the current density increased to 10 Ag[Formula: see text], demonstrating outstanding rate performance. The composite NCS2//AC supercapacitor exhibits an energy density of 24.2 Whkg[Formula: see text] at power density of 800 Wkg[Formula: see text], even though after 1000 consecutive charge-discharge cycles, the capacity retention rate remained high at 77.1%, validating the exceptional stability and reliability of the NCS2 material during cycling. This work employs microwave sulfidation for the rapid and controlled synthesis of nickel cobalt sulfides, providing a green and efficient synthetic strategy for metal sulfide active materials.

Graphene wrapped porous polyaniline/manganese oxide nanocomposites with enhanced structural stability and conductivity for high‐performance symmetric supercapacitor

AbstractManganese oxides have emerged as promising electrode materials for supercapacitors. Despite extensive efforts to improve their conductivity and structural stability through various manganese oxide/conductor nanocomposites, achieving efficient and reliable energy storage electrode materials has remained challenging. In this study, we propose a meticulous “dual enhancement” strategy, where three‐dimensional (3D) nanostructured polyaniline/manganese oxide composites (PM) are synthesized via an in situ method and further integrated with graphene wrapping to form polyaniline/manganese oxide/graphene nanocomposites (PMG). Electrochemical characterization reveals that PMG exhibits a remarkable specific capacitance of up to 403 F g−1 (at 1 A g−1), with a favorable capacitance retention of 80.2% after 5000 cycles, along with a wide potential window. This enhancement is attributed to the synergistic effects of polyaniline, which provides a supportive framework and electron transport pathways, and graphene, which offers external protection and enhances conductivity pathways. Assembled symmetrical supercapacitors demonstrate outstanding energy density (32.7–23.3 Wh kg−1) and power density (720–4500 W kg−1) at a high operating voltage of 1.8 V, surpassing the performance of many reported high‐performance supercapacitors. This study provides valuable insights for advancing manganese oxide electrode materials and is expected to catalyze their widespread adoption in energy storage applications.Highlights “Dual enhancement” is implemented by PANI supporting and rGO wrapping. The conductivity and structural stability of composite electrode is greatly enhanced. Improved capacitance (403 F g−1, 1 A g−1) and cycling stability (80.2%) is achieved. The symmetrical supercapacitor has high voltage and energy density (32.7 Wh kg−1).

Surface chemo-mechanics coupling of MnO2/Au layered composites under electrochemical environment

The intersection of surface mechanics and electrochemistry has gradually become a prominent topic in the realm of new energy research. To explore the influence of the electrochemical process on the stress of energy storage electrode composite, supercapacitor material manganese dioxide (MnO2) was selected as the coating and the MnO2/Au composites were prepared by the electrochemical deposition. The surface stress of MnO2/Au composites under different electrochemical modes and the stress variation law of MnO2 with varying thicknesses were determined. The addition of MnO2 could alter the stress response and the strain magnitude of the gold electrode with varied electrochemical potential. The reversible tensile strain within the Au surface during 0.3 ∼ 0.8 V charging was induced by the absorption of SO42−, while the compressive strain of the MnO2/Au composites was related to the extraction of Na+ ions resulting from the redox pseudocapacitance of MnO2. Notably, the produced stress exhibited a linear correlation with the capacitance. And the long-cycle tests revealed that as the specific capacitance of electrodes decreased, the induced tensile stress progressively diminished. This study emphasized the surface chemo-mechanics coupling of both the Au layer and MnO2/Au composites, which would provide a new approach to regulating surface strain in the solid–liquid interface.

Pr6O11 modification effectively enhancing sodium storage for Na3V2(PO4)3 batteries

Na3V2(PO4)3 (NVP) is one of the most promising cathode materials for sodium-ion batteries (SIBs) due to its robust three-dimensional framework, high tunability, and relatively high Na+ intercalation potentials. However, its utility is generally constrained by low conductivity, inefficient charge transfer, and subpar interface kinetics. This work presents an efficient and simple method to address these issues. We innovatively modified the NVP surface with Pr6O11 nanoparticles, a negative temperature coefficient (NTC) thermosensitive material, to enhance interface compatibility with electrolytes and improve conductivity. This modification significantly enhances the overall sodium-ion storage performance. Specifically, the optimized NVP-2 %Pr6O11 electrode exhibits excellent electrochemical properties with the aid of an optimized conductivity network compared to the unmodified NVP. Cycled at an 8C current density, the NVP-2 %Pr6O11 electrode achieves high specific capacities of 102.6 mAh·g−1 at 27 °C and 95.6 mAh·g−1 at 45 °C. After 1000 cycles, the capacity retention rates are 81.18 % and 78.97 %, respectively, significantly higher than the 20.59 % and 14.99 % of pure NVP. In coin full-battery testing, the NVP-2 %Pr6O11 electrode retains 89.76 % capacity after 500 cycles at 8C. In addition, the assembled The NVP-2 %Pr6O11//HC pouch full battery exhibits better sodium-ion storage and thermal safety performance compared to the NVP-SP//HC battery. This simple modification strategy provides an effective insight into the application of NVP electrodes in energy storage.

Synthesis of Carbon Nanofibers from Lignin Using Nickel for Supercapacitor Applications

Carbon fiber is known for being lightweight and adaptable, making it useful for various current and future applications. However, to broaden the use of carbon fibers beyond niche applications, production costs must be lowered. A potential approach to achieving this is by using more affordable raw materials, such as lignin, which is renewable, cost-effective, and widely available compared with the materials commonly used in industry today. This study explores the impact of metal ions on the quality of carbon fiber derived from lignin, focusing on its mechanical and electrochemical properties and morphology. The effect of a specific metal ion (Ni(NO3)2·6H2O) was examined by incorporating it into the spinning solution. The carbonization stage of the fiber was conducted at temperatures of 800, 900, and 1000 °C in an inert atmosphere. Scanning electron microscopy (SEM) analysis showed no defects or damage in any of the fibers. Therefore, it was concluded that moderate concentrations of Ni2+ ions in the fibers do not influence the stabilization or carbonization processes, thus leaving the mechanical properties of the final carbon fiber unchanged. These carbon nanofibers were also tested as a sustainable alternative to the non-renewable materials used in electrodes for energy storage and conversion devices, such as supercapacitors. Electrochemical performance was assessed in a 6 M KOH solution using a two-electrode cell configuration. Galvanostatic charge–discharge tests were performed at different current densities (0.1, 0.25, 0.5, 1.0, and 2.0 A g−1). The specific capacitance of the carbon nanofibers was determined from CVA data at various scan rates: 5, 10, 20, 40, 80, and 160 mV s−1. The results indicated that at 0.1 A g−1, the capacitance reached 108 F g−1, and at a scan rate of 5 mV s−1, it was 91 F g−1. The innovation of this work lies in its use of lignin, a renewable and widely available material, to produce carbon fibers, reducing costs compared with traditional methods. Additionally, the incorporation of nickel ions enhances the electrochemical properties of the fibers for supercapacitor applications without compromising their mechanical performance.

Fluorinated reduced graphene oxide nanosheets for symmetric supercapacitor device performance

This study explores the potential of using spent lithium-ion battery anodes (graphite) for fabricating symmetric energy devices through a simple regeneration process. Specifically, the use of fluorine-doped reduced graphene oxide (RGO) nanosheets derived from waste batteries as the basis for a symmetric supercapacitor (SC) device is investigated. To enhance the electrochemical energy storage capabilities, a facile hydrothermal technique is employed to synthesize fluorinated graphene. Fluorination of the graphene sheets is successfully realized, as confirmed by the presence of boron with a 2.94 at.% fluorine-doped level, according to the Energy dispersive spectroscopy (EDS) spectrum analysis. Electrochemical analysis of the F-RGO electrode performance consistent with electric double-layer capacitance. Moreover, with a three-electrode system, the F-RGO electrode achieves a maximum specific capacitance of 207F/g under a current density of 1 A/g. A two-electrode symmetric device employing F-RGO exhibits a specific capacitance of 54F/g at 1 A/g. Furthermore, electrochemical impedance measurements demonstrate low charge transfer resistance (Rct) values, specifically 8.63 Ω for F-RGO, signifying improved electrochemical performance. Thus, fluorine atomic doping in RGO nanosheets contributes to the improvements of the specific capacitance and overall superior electrochemical performance of F-RGO, and F-RGO is a highly electrochemical active material for high-performance energy storage electrodes for SCs.