Capacitance Values Research Articles

Closed-loop control strategy design for Caputo–Fabrizio definition-based fractional-order Boost converters considering parametric uncertainties

This paper proposes a dual closed-loop adaptive PI control system based on parameter identification for Caputo–Fabrizio (C-F) definition-based fractional-order boost converters. First, a C-F definition-based fractional-order model of the Boost converter is derived. Afterward, an online component parameter identification method is proposed to obtain the values and orders of capacitors and inductors in the proposed model. Based on these identified parameters, a dual closed-loop adaptive PI control system considering parametric uncertainties for the Boost converters is designed using the frequency domain analysis method. Finally, simulation validations are conducted. The online parameter identification method can accurately identify the values and orders of capacitors and inductors. The identification error is less than [Formula: see text] for the capacitance value and [Formula: see text] for the other parameters. Moreover, the proposed control system can automatically adjust the parameters with changes in the component parameters, effectively improving the robustness. Compared to traditional PI controllers, when the parameters of components change, the proposed control system can reduce voltage overshoot by [Formula: see text] in the case of sudden changes in the input voltage. These results confirm the efficacy of the proposed online parameter identification method and the dual closed-loop adaptive PI control system.

Chitosan-Based Electronics: The Importance of Acid Strength and Plasticizing Additives on Device Performance.

A rise in demand for disposable consumer electronics such as smart packaging, wearable electronics, and single-use point-of-source sensors requires the development of eco-friendly and compostable electronic materials. Chitosan is derived from crustacean waste and offers high dielectric constant values without requiring rigorous purification, making it sustainable for large-scale electronic device manufacturing. When processed in acidic media, the protonated backbone of chitosan pairs with counterions from the acid dissociation to form chitosan thin films with electrical double layers (EDLs) and tunable capacitive properties. We report the importance of the choice of acid when processing chitosan by surveying a series of halogenated and biosourced acids with varying pKa values and solutions with different pH values. Oxalic acid outperforms other acids, with a maximum areal capacitance of 161 nF·mm-2. Tartaric acid and citric acid, despite lower capacitance values, showed promising results with a stable EDL capacitance and high reproducibility, making them optimal for large-area manufacturing. The incorporation of sorbitol as a plasticizer boosts the EDL formation onset of all chitosan-acid combinations to 1 × 103-105 Hz and improves reproducibility. High-performing single-walled carbon nanotube thin film transistors were made using chitosan-based dielectrics treated with different acids with and without sorbitol, leading to transconductance as high as ≈5.2 μS and Ion/Ioff of 105. The capacitors and transistors remain functional after one year of storage in ambient conditions. Overall, this study demonstrates durable high-performance electronics based on chitosan and stresses the importance of processing acid and the use of plasticizing additives, such as sorbitol.

Red Carbon Dots Sensitized Ni‐Doped 2D MoS2 Nanosheets as Electrode Materials for Visible‐Light Active Photorechargeable Supercapacitors

Developing photorechargeable electrochemical devices has become a new paradigm for addressing the efficient utilization of solar energy for renewable energy research. Herein, a unique 0D/2D heterostructure made of red carbon dots (RCDs) and Ni‐doped MoS2 nanosheets (NMS) has been designed as electrode materials for photorechargeable supercapacitor device. Polyvinyl alcohol (PVA) has been used as a transparent matrix for the electrode, which retains the intrinsic optoelectronic properties of the composite. Photophysical properties suggest that RCDs act as efficient light‐harvesting materials as well as visible‐light photosensitizer for the device. Suitable bandgap alignment of both counterparts facilitates the photoinduced charge separation. Finally, the composite has been utilized as a visible‐light‐sensitive photorechargeable supercapacitor device. Almost 95% of enhancement in the capacitance value has been observed under light irradiation compared to the dark condition. Furthermore, wavelength dependence device performances, photo charging, and galvanostatic discharging measurements have been investigated to analyze the overall performance of the device. The device is capable of retaining its 97.25% capacity after 1000 full cycles, suggesting its excellent photostability. The plausible mechanism for photoinduced rechargeable supercapacitance properties has been discussed in detail.

Electromechanical modelling and vibration control analysis of cyclic symmetric structures with a piezoelectric vibration absorber

This study explored the application of piezoelectric vibration absorbers (PVAs) equipped with synthetic circuits for the vibration control of cyclic symmetric structures. A cyclic symmetric electromechanical model (CSEM) integrated with PVAs was introduced to facilitate the design and optimization of the PVAs. This model was formulated analytically based on the circulant matrix theory, and the dynamic response was computed using the complex mode superposition method with explicit consideration of the intrinsic resistance within the PVA. A case study involving a simplified blisk model and an experimental test rig was conducted to validate the proposed CSEM. The validity of the model was confirmed through a comparative analysis of both the natural and dynamic characteristics obtained using the finite element model and experimental results. Furthermore, the impact of synthetic circuit parameters (inductance and negative capacitance values) and the placement of piezoelectric patches on the vibration control performance of PVA were investigated. The results suggested that the optimal inductance coincide with the analytical value, whereas the optimal negative capacitance of the series was slightly greater than the intrinsic capacitance of the patch. Additionally, mounting the piezoelectric patch on the blade root improved the vibration control.

One‐Step Electrodeposition of Iron Oxyhydroxide Onto 3D Porous Graphene Substrates for on Chip Asymmetric Micro‐Supercapacitors

AbstractElectrochemical capacitors based on redox active materials can achieve greater capacitance values than traditional electric double layer composites. Herein, electrodeposition of iron oxyhydroxide from a mildly acidic acetate precursor is reported. The one‐step deposition resulted in a submicron film composed of FeOOH phase, which was confirmed via Raman and x‐ray photoelectron spectroscopy. The capacitance increased linearly with loading amount and achieved a maximum at 1600 mC deposition with 120 mF cm−2 at 25 mV s−1 after which the film became more resistive, limiting electrolyte access to the porous graphene substrate. The deposited FeOOH demonstrated promising rate capability and good cycling stability, without phase changes, retaining 82 % of the initial capacitance after 5000 consecutive charge/discharge cycles. The charge storage mechanism of FeOOH was determined via in situ Raman spectroscopy, which followed reversible iron oxygen vibration changes upon cycling which become more intense upon reduction as a result of sodium ion intercalation. Furthermore, an asymmetric configuration full cell combining FeOOH/MnO2 allowed the working voltage to be extended to 2 V, maintaining an ideal capacitor behaviour, and achieving a maximum energy and power density of 21 μWh cm−2 and 2.5 mW cm−2 respectively.

Graphene‐based Supercapacitor Using Microemulsion Electrolyte

AbstractGraphene‐like material prepared by a facile combustion synthesis was investigated as an electrode material in a microemulsion electrolyte. Notably, a stable voltage window of 2.2–2.4 V was achieved, surpassing previous reports for aqueous‐based electrolytes on similar materials. The fabricated supercapacitor device exhibited a commendable specific capacitance values of 59 F g−1 at 0.1 A g−1 and 32 F g−1 at 5 A g−1, indicating its potential for high‐current applications. Mechanistic examination revealed that the charge storage primarily relies on electric double‐layer formation, with minor non‐capacitive contribution from electrode surface functionalities and the supporting electrolyte. Further analysis showed significant capacitive contributions of 85 % at 2.2 V and 67 % at 2.4 V, underscoring the dominance of the capacitive process. The fabricated supercapacitor's stability indicated a decrease as the non‐capacitive process intensified, suggesting that electrode surface functionalities predominantly contribute to cell deterioration at elevated potentials. These results highlight the potential efficacy of microemulsion electrolytes in energy storage applications.

Role of synthetic process parameters of nano-sized cobalt/nickel oxide in controlling their structural characteristics and electrochemical energy performance as supercapacitor electrodes

The synthesis of nano-sized bimetallic Cobalt/Nickel oxides (Ni1.5Co1.5O4) with a 1:1 Co/Ni atomic ratio has been achieved using a surfactant-free co-precipitation/hydrothermal process. The growth mechanism of Cobalt/Nickel oxides Ni1.5Co1.5O4 is elucidated by tuning the synthesis process parameters, including co-precipitation pH and hydrothermal time. The formation of Cobalt/Nickel oxides Ni1.5Co1.5O4 oxide began with the nucleation of cobalt nickel hydroxide nanoplates through the co-precipitation process, followed by dissolution-recrystallization, stacked hexagonal nano-flakes, and a flower-like microstructure. The electrochemical performances of the oxides were evaluated, with the largest surface area observed at pH 9 being the main factor for the best super-capacitive performance. As hydrothermal time increased, the structural directing growth forward, resulted in the formation of a nano-flower structure with a larger surface area. The as-prepared cobalt nickel oxide exhibited a maximum specific capacitance value of 525.5 F g-1 at a current density of 1 A g-1 and energy and power densities of 88.2 WhKg-1 and 606 WKg-1, respectively.

Ionic polymer-metal composite (IPMC) as a flexible capacitor: an experimental study

Abstract In recent years, significant research has been directed towards the development of energy storage devices that are thin, lightweight, and flexible, catering to the diverse demands of modern smart electronics. This study investigates the remarkable adaptability of ionic polymer metal composite (IPMC) capacitors when subjected to bending conditions. Under investigation was the capacitor’s functionality within a broad spectrum of bending angles, ranging from 0 ∘ to 100 ∘ . The study aims to reveal the capacitor’s response and stability across this expansive curvature range, providing insights into its potential applications in flexible and dynamic systems. The flexibility of the supercapacitor allows it to bend or fold up to 180 ∘ without experiencing permanent mechanical deformation. The calculated specific capacitance values obtained by bending the cell at angles of 0, 40, 70, and 100 ∘ are found to be 4.3, 6.4, 8.2, and 8.4 mF g−1 respectively. The result displayed the IPMC capacitor exhibited notable resilience under varying bending angles, affirming its capacity to maintain operational integrity despite significant mechanical stress. Through a systematic exploration of bending conditions, this research unveils the capacitor’s ability to flexibly conform to various bending angles. This adaptability is particularly significant for applications where traditional rigid capacitors may be impractical or inefficient.

The dielectric characteristics of spray deposited α-Si3N4:ZnO thin films: The nitride effect on frequency-dependent capacitance and conductance profiles

The study focused on the effect of α-Si3N4 doping on the electrical/dielectric properties of ZnO thin films. Both α-Si3N4 doped and additive-free ZnO thin films were coated on p-Si substrates via a spray deposition method to achieve this. The electrical (current density (J)-voltage (V)) and dielectric properties (capacitance (C), conductance (G), dielectric loss (tanδ), reel/imaginary part of dielectric permittivity (ε′ and ε″) and electric modulus (M′ and M″)) were determined for all samples by using dielectric spectroscopy (DS) method. On the other hand, scanning electron microscopy (FESEM) and energy-dispersive spectroscopy (EDS) analysis were performed to evaluate microstructure, X-ray diffraction (XRD) was used to define chemical composition and atomic-force microscopy (AFM) analysis was carried out to characterise the topology of the coating layers. The thickness/surface roughness was obtained as ∼82.5 nm/10.6 nm for undoped and ̴ 99.5 nm/10.4 nm for nitride-doped samples, respectively. The maximum capacitance value (C) was obtained as 275 pF at −3.0V and 200 Hz, and the optimal conductance (G) value was also found as 45 μS around 4.0V and 1 MHz in the nitride-doped sample. The average of α and τ values was calculated as 5.67 × 10−5 s, 0.146 and 4.49 × 10−5 s, 0.081 for nitride-doped and undoped ZnO, respectively. The increase in performance can be attributed to the homogeneous and almost equally-size distribution of the ZnO grain growth which is strongly controlled by α-Si3N4.

Lignin Nanofiber Flexible Carbon Aerogels for Self-Standing Supercapacitors.

Renewable feedstocks are sought for clean technology applications, including energy storage applications. In this study, LignoForce™ lignin, a biobased aromatic polymer commercially isolated from wood, was fractioned into two parts using acetone, and the resulting lignin fractions had distinct thermo-rheological behavior. These two fractionated lignins were combined in various ratios and transformed into nanofibers by electrospinning. Subsequently, electrospun fiber materials were disrupted by agitating the mats in water, and the materials were transformed into ultralight 3D aerogels through lyophilization and post-process controlled heating. Using only this combination of two fractions, the morphology of lignin nanofibers was tailored by heat treatment, resulting in lignin aerogels with high flexibility and significant shape recovery properties. Various microscale structures of lignin fibers impacted the resulting physical properties of the elastic aerogel materials, such as resilience, compressive strength, and electrical conductivity for the corresponding carbonized samples. By exploiting lignin's sensitivity to heat and tailoring the thermal properties of the lignin through fractionation, the work provided an interesting path to form robust lignin-derived functional materials without any toxic chemical additives and significant ability to serve as free-standing electrodes with specific capacitance values better than some graphene-based supercapacitors.

A Study of the Effect of Temperature on the Capacitance Characteristics of a Metal-μhemisphere Resonant Gyroscope.

Metal-μhemispherical resonant gyros (M-μHRGs) are widely used in highly dynamic navigation systems in extreme environments due to their high accuracy and structural stability. However, the effect of temperature variations on the capacitance characteristics of M-μHRGs has not been fully investigated, which is crucial for optimizing the performance of the gyro. This study aims to systematically analyze the effect of temperature on the static and dynamic capacitances of M-μHRGs. In this study, an M-μHRG structure based on a 16-tooth metal oscillator is designed, and conducted simulation experiments using non-contact capacitance measurement method and COMSOL Multiphysics 6.2 finite element simulation software in the temperature range of 233.15 K to 343.15 K. The modeling analysis of the static capacitance takes into account the thermal expansion effect, and the results show that static capacitance remains stable across the measured temperature range, with minimal effect from temperature. The dynamic capacitance exhibits significant nonlinear variations under different temperature conditions, especially in the two end temperature intervals (below 273.15 K and above 313.15 K), where the capacitance values show local extremes and fluctuations. In order to capture this nonlinear behavior, the experimental data were smoothed and fitted using the LOESS method, revealing a complex trend of the capacitance variation with temperature. The results show that the M-μHRG has good capacitance stability in the mid-temperature range, but its dynamic performance is significantly affected at extreme temperatures. This study provides a theoretical reference for the optimal design of M-μHRGs in high- and low-temperature environments.

A novel impact approach based on electromagnetic loading technology: A case study on CFRP/Al riveted structures

To investigate the mechanical response and damage behavior of aircraft fuselage composite structures under out-of-plane impact loads more efficiently and flexibility, this paper proposed a novel impact approach and testing platform based on inductive coils to yield electromagnetic impact force. The influence of system key parameters on the electromagnetic loading waveforms were analyzed using an electromagnetic field finite element model. Single/repeated impact tests on CFRP/aluminium alloy (Al) riveted structures were conducted at different voltages (energies) based on this approach. The results indicate that the electromagnetic impact (EMI) approach exhibits significant advantages in both variable strain rate loading and continuous impact loading scenarios. This device can efficiently achieve multi-point and multiple impact loading. The electromagnetic impact forces with various amplitudes and pulse-widths can be accurately obtained by altering voltage and capacitance values, which can demonstrate the good experimental consistency of such test approach. Besides, with this test method, the load threshold for damage formation can be clearly defined: once the impact force exceeds the damage threshold load, the delamination area of the CFRP laminates expand as the impact energy increases. Note that when the provided out-of-plane impact load is slightly higher than the damage threshold load by changing the voltage, significant delamination damage may suddenly manifest in any one impact event of the repeated impacts.

Critical role of submicropores in lignin-based carbon for enhanced supercapacitive performance in aqueous electrolyte

Lignin-based microporous carbon is prepared by KOH activation method. Nitrogen sorption analysis shows that the specific surface area is 1473 m2 g−1 and the micropore size is mainly distributed at 0.65 nm, leading to a capacitance value of 252 F g−1 in H2SO4 electrolyte. To tune the microstructure for better electrochemical performance, cobalt acetate is introduced in the mixture of lignin/KOH. The catalysis of cobalt acetate reduces the heteroatom content of the final porous carbon, resulting in an increased graphitization degree. Moreover, the microporous structure is also tuned by generating more submicropores with pore size of 0.65–0.85 nm. Even though the specific surface area is only 1543 m2 g−1, the submicropore surface area is increased to 1097 from 662 m2 g−1. With the increased graphitization degree and submicropore content, the prepared porous carbon can accommodate more electrolyte ions, contributing to a specific capacitance of 332 F g−1 in H2SO4 electrolyte. This capacitance value is increased by 31.7 % compared with previous carbon without adding cobalt acetate. The assembled supercapacitor cell can deliver a high energy density of 13.4 Wh kg−1. Our findings provide a guide on the microstructure modulation of porous carbon to match aqueous electrolytes with different ionic size.

A Theoretical Framework to Quantify Ecosystem Pressure-Volume Relationships.

'Water potential' is the biophysically relevant measure of water status in vegetation relating to stomatal, canopy and hydraulic conductance, as well as mortality thresholds; yet, this cannot be directly related to measured and modelled fluxes of water at plot- to landscape-scale without understanding its relationship with 'water content'. The capacity for detecting vegetation water content via microwave remote sensing further increases the need to understand the link between water content and ecosystem function. In this review, we explore how the fundamental measures of water status, water potential and water content are linked at ecosystem-scale drawing on the existing theory of pressure-volume (PV) relationships. We define and evaluate the concept and limitations of applying PV relationships to ecosystems where the quantity of water can vary on short timescales with respect to plant water status, and over longer timescales and over larger areas due to structural changes in vegetation. As a proof of concept, plot-scale aboveground vegetation PV curves were generated from equilibrium (e.g., predawn) water potentials and water content of the above ground biomass of nine plots, including tropical rainforest, savanna, temperate forest, and a long-term Amazonian rainforest drought experiment. Initial findings suggest that the stored water and ecosystem capacitance scale linearly with biomass across diverse systems, while the relative values of ecosystem hydraulic capacitance and physiologically accessible water storage do not vary systematically with biomass. The bottom-up scaling approach to ecosystem water relations identified the need to characterise the distribution of water potentials within a community and also revealed the relevance of community-level plant tissue fractions to ecosystem water relations. We believe that this theory will be instrumental in linking our detailed understanding of biophysical processes at tissue-scale to the scale at which land surface models operate and at which tower-based, airborne and satellite remote sensing can provide information.

Molten Salt Assisted Assembly (MASA) of novel mesoporous Ni0.5Mn0.5Co2O4 for high-performance asymmetric supercapacitors

Mesoporous transition metal oxides (TMO) are immensely investigated as electrode materials in supercapacitors. The molten salt assisted self-assembly (MASA) process enables a facile route for the synthesis of the mesoporous TMO. In this study, mesoporous nickel manganese cobaltite (Ni0.5Mn0.5Co2O4) is synthesized for the first time using a MASA process and is evaluated as a novel electrode-active material for asymmetric supercapacitors. The objective of this work is to quantitatively measure the performance improvement in the Ni0.5Mn0.5Co2O4 electrode based on its composition and reveal the improvement mechanism through electrochemical methods. The electrochemical performance of the NiCo2O4 and MnCo2O4 prepared by MASA is also investigated, in order to understand the synergistic effect of Ni and Mn elements in the same cobaltite structure. In line with the data obtained from half cells, a full asymmetric cell is prepared by assembling the appropriate amount of Ni0.5Mn0.5Co2O4 and activated carbon through the charge balance theory. The test results show that the specific capacitance (Cs) values are 2.62F/cm2 (92.1F/g) for mesoporous NiCo2O4, 0.26F/cm2 (9.8F/g) for mesoporous MnCo2O4, and 9.53F/cm2 (338.5F/g) for mesoporous Ni0.5Mn0.5Co2O4 under the test conditions of 5 mA/cm2. The asymmetric supercapacitor assembled with Ni0.5Mn0.5Co2O4 and activated carbon demonstrates a superior energy density of 79.52 Wh.kg−1 at 1 mA/cm2. The findings of the study highlight the importance of substituting the electrode with Ni0.5Mn0.5Co2O4 to enhance the Cs by achieving proper surface properties and electrochemical activity.

Preparation of microalgae-based carbon materials with Ni(OH)2 doping and their electrochemical performance

Supercapacitors are a new type of energy storage devices with many advantages. In this study a novel composite material named NiC were synthesized to improved their electrochemical performance in supercapacitors. It was composite of Ni(OH)2 and microalgae-based N-doped activated carbon materials. Activated carbon material prepared from defatted microalgae was excellent electrode material because of their nitrogen-rich characterization and porous structure. The Ni(OH)2 as a metallic material could provide considerable pseudo-capacitance for capacitors. In this study, Ni(OH)2 was successfully doped into carbon materials using a hydrothermal method at a temperature of 150 °C for 4 h. The flower-like structure of metallic materials was observed in SEM images and two forms of elemental Ni ions (Ni3+ and Ni2+) were detected in XPS. The porosity of the composite materials NiC was retained to some extent (specific surface area of 502 m2/g for sample NiC10). Moreover, the specific capacitance value of composite material NiC20 was increased by 190 % compared to its parent carbon material, indicating that the capacitive performance of the composite materials was significantly improved. The capacitance retention of NiC20//NiC20 in a two-electrode system was up to 75.29 % over 5000 cycles. This research will provide necessary information for high-performance electrochemical materials based on microalgae-based carbon materials.

The effect of Fenton sludge on anaerobic digestion of papermaking wastewater in an upflow anaerobic sludge blanket reactor

An upflow anaerobic sludge blanket (UASB) reactor was used to investigate the effect of adding Fenton sludge (FS) on the anaerobic digestion of actual papermaking wastewater. The results showed that a one-time addition of 10 g/L FS could sustainably promote the performance of UASB for more than 40 days. The organic matter removal efficiency increased by 15.56%, and the biogas production increased by 24.52%. The proportion of methane in biogas increased by 12.87%. Adding FS increased the capacitance values of sludge extracellular polymeric substances and the electron transfer system activity in reactor increased by 1.76 times. The dehydrogenase activity and coenzyme F420 of the sludge increased by 1.54 and 2.11 times, respectively. Adding FS enriched the iron-reducing bacteria (Thermodesulfobacteriota) and hydrolytic acid-producing bacteria (Chloroflexota and Synergistota), thereby promoting the hydrolysis and acidification process. Adding FS was beneficial to the enrichment of methanogen, especially Methanosaeta, significantly increasing the methane production.

Facile Synthesis of Highly Supercapacitive Mo‐doped Titanium Nanotube Arrays and Effect of Anodization Voltage

AbstractDesigning potential architectures by the modification of conventional electrode materials is an effective approach in the development of high performance supercapacitor electrodes. The present study investigated the effect of varying anodization voltages (50, 75, and 100 V) on the morphology and electrochemical properties of titanium nanotubes (TNT). Molybdenum was doped onto TNT using a simple hydrothermal procedure, followed by thermal treatment at 450 °C. The study effectively demonstrated control over the dimensions of the nanotube structure by adjusting the anodization voltage. Additionally, it was found that the tube diameters were increased due to etching during the hydrothermal treatment with the Mo precursor, which potentially enhanced the supercapacitive performance of Mo‐doped TNT. Further, structural analysis revealed that Mo doping improved both crystallinity and electrode stability. With an optimal anodization voltage of 100 V, TNT and Molybdenum‐doped TNT could exhibit capacitance value of 13.34 and 326.54 mF cm−2 respectively, at a current density of 1 mA cm−2. Furthermore, the electrode demonstrated good cyclic stability with 88% capacitance retention and 97% coulombic efficiency after 5000 cycles. An impressive energy density of 87.03 µWh cm−2 and a power density of 799.99 µW cm−2 could be achieved with this sample in an asymmetrical device.

Polyoxometalates-based metal-organic frameworks with conjugated acid-base pairs for proton supercapacitors

The design and construction of electrode materials with high specific capacity and excellent cycling stability represents a crucial and challenging for the development of supercapacitors. Polyoxometalates (POMs)-based metal–organic frameworks, which are obtained via self-assembling of POMs and organic ligands, showcase high redox capability and stability and are suitable for electrode materials of supercapacitor with high specific capacity and high stability. Three new Dawson-type POM-based metal–organic frameworks (POMOFs), [(Cu3(MPT)2(H2O)3)[P2W18O62]]·12H2O (CUST-831), [(Cu3(MPTD)2(H2O)7)[P2W18O62]]·6H2O (CUST-832) and [(Co2(HMPTZ)2(H2O)4)[P2W18O62]]·9H2O (CUST-833) have been successfully synthesized under hydrothermal conditions via tuning nitrogen heterocycles-based organic ligands. All three Dawson-type POMOFs exhibited impressive specific capacitance values of 225, 305, and 430F g−1, respectively, at a current density of 1 A g−1. The theoretical calculations and experiments indicated that the enhanced performance of CUST-833 is attributed to its higher proton conductivity. The two uncoordinated N atoms on the organic ligand in CUST-833 form a “conjugated acid-base pair” that facilitates rapid proton transport. This work provides new insights into the design and synthesis of proton-conducting materials based on POMs in their crystalline state for supercapacitors.

Activated biomass-derived 3-dimensional porous graphene-like carbon for high-performance energy storage electrode materials

This article reports studies on the fabrication of active material for supercapacitor electrodes, from 3D porous graphene-like carbon (GLC), synthesized by carbonization from coffee waste (CW) and tea waste (TW) at 550 °C, followed by thermochemical activation in KOH at 850 °C in a quartz tubular furnace. The microstructure of coffee and tea waste shows the form of micro- and mesopores during carbonization and further chemical activation forms hierarchically highly porous 3D graphene-like carbon. GLC-CW exhibited a higher specific surface area (SSA) of 3486 m2/g according to the Brunauer-Emmett-Teller (BET) method, compared to GLC-TW, which had an SSA of 2407 m2/g. These results highlight the effectiveness of graphene-like carbon derived from coffee and tea waste, demonstrating its potential as a promising material for high-capacity supercapacitors. The electrochemical characteristics of the assembled supercapacitors using GLC-CW and GLC-TW revealed significantly higher specific capacitance values of 214 F/g and 182 F/g respectively, along with cycling stability of 98 % and 95 % during 5000 cycles of charge and discharge at 2 A/g current density. This approach can produce high-performance electrode materials for supercapacitors at a reasonable cost and with easy scalability.