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In this study, a three-dimensional (3D) interconnected porous Ni/SiC skeleton (3D Ni/SiC) was synthesized by binder-free hydrogen bubble template-assisted electrodeposition in an electrolyte containing Ni2+ ions and SiC nanopowders. This 3D Ni/SiC skeleton served as a substrate for directly synthesizing nickel–cobalt layered double hydroxide (LDH) nanosheets via electrodeposition, allowing the formation of a nickel–cobalt LDH nanosheet-decorated 3D Ni/SiC skeleton (NiCo@3D Ni/SiC). The multiscale hierarchical structure of NiCo@3D Ni/SiC was attributed to the synergistic interaction between the pseudocapacitor (3D Ni skeleton and Ni–Co LDH) and electrochemical double-layer capacitor (SiC nanopowders). It provided a large specific surface area to expose numerous active Ni and Co sites for Faradaic redox reactions, resulting in an enhanced pseudocapacitance. The as-fabricated NiCo@3D Ni/SiC structure demonstrated excellent rate capability with a high areal capacitance of 1565 mF cm−2 at a current density of 1 mA cm−2. Additionally, symmetrical supercapacitor devices based on this structure successfully powered commercial light-emitting diodes, indicating the potential of as-fabricated NiCo@3D Ni/SiC in practical energy storage applications. [ABSTRACT FROM AUTHOR]

Developing high-performance energy storage devices using sustainable materials is essential for their widespread application in electronic devices. The energy density of carbon-based electric double-layer capacitors (EDLCs) can be optimized through the integration of polymer-based electrolytes and ionic liquids. Poly(vinyl alcohol) (PVA)-based gel electrolytes, in particular, have attracted significant interest due to their solubility, biodegradability, and biocompatibility. In this study, we fabricated EDLC samples employing a PVA gel polymer electrolyte (GPE) enhanced with an ionic liquid and phosphoric acid. Our focus was on developing a proton-conducting PVA-based GPE and utilizing activated carbon as the electrode material. Optimal performance was achieved with an ionic liquid concentration of 25 wt% in a GPE film placed between the carbon-based EDLC electrodes. The device demonstrated a discharge specific capacitance of 45.8 F/g with stable performance over extensive cycling tests. [ABSTRACT FROM AUTHOR]

The utilization of tetraethylammonium perfluorobutane sulfonate as a promising alternative salt for electrolyte solutions in electrochemical double layer capacitors is introduced in this study. A thorough analysis of the physical and electrochemical characteristics of tetraethylammonium perfluorobutane sulfonate was conducted, including the assessment of its ionic conductivity, viscosity, and thermal behavior, using a 1 M solution in acetonitrile. Comparative assessments were made between the performance of this novel electrolyte and two well‐studied electrolytes: 1 M tetraethylammonium tetrafluoroborate and 1 M tetraethylammonium bis(trifluoromethanesulfonyl)imide in acetonitrile, focusing on electrochemical performance and long‐term stability. Furthermore, an investigation into the impact of tetraethylammonium perfluorobutane sulfonate on the anodic dissolution of aluminum current collectors was conducted. The results highlight the potential of tetraethylammonium perfluorobutane sulfonate as an effective replacement for bis(trifluoromethanesulfonyl)imide‐based electrolytes. [ABSTRACT FROM AUTHOR]

In this work, new plasticized solid polymer electrolytes (SPEs) are developed using MC (methylcellulose) as a polymer host, and sodium iodide (NaI) as a dopant via the solution casting method. Ethyl carbonate (EC) is used as a plasticizing agent to improve the properties of the SPEs. Polarized optical microscopy analysis reveals that the surface morphology of the MC‐NaI‐EC films contained porous amorphous regions owing to the presence of EC. The complex formation between MC, NaI, and EC is confirmed by Fourier‐transform infrared spectra. The addition of EC in the MC‐NaI polymer salt matrix enhances the electrochemical properties of the prepared films. The highest ionic conductivity of 5.06×10−3 S/cm is achieved for the composition: MC+50 wt. % NaI +10 wt. % EC. The linear sweep voltammetry test reveals that the optimal plasticized‐SPE can withstand up to 2.5 V. The ionic transference number analysis reveals that 99% of ions contribute to the total conductivity. The optimized SPE film and graphene oxide‐based electrodes are used to manufacture a solid‐state electrical double‐layer capacitor. The coulomb efficiency of the supercapacitor cell is 100%, and the specific capacitance of the supercapacitor is found to be 18.56 F/g utilizing impedance data at low frequency. [ABSTRACT FROM AUTHOR]

Aging processes occurring in electrical double layer capacitors greatly influence the lifetime of these energy storage devices and an increasing attention has been directed toward their understanding. While most studies approach this topic based on the overall electrochemical performance of the cell (such as enhanced resistance) or the materials degradation, addressing its failure causes at the electrolyte level is of great importance. Doing so, more precise strategies to improve the lifetime and performance can be developed for a wide range of applications. This article provides an overview of the current state of separation tools regarding gas chromatography and detection tools in various combinations with mass spectrometry. The aim of this work is to present the present state of the current knowledge on aging processes, with a focus on gas chromatography and mass spectrometry. Then, an outlook onto the challenges as well as ideas of combining methods is given. Here, the work offers a judgement into future challenges. [ABSTRACT FROM AUTHOR]

This study explored the development of hierarchical graphitic carbon structures (HGCs) from harmful inedible seaweed waste harvested in the summer. Elevated sea temperatures during the summer increase the cellulose content of seaweeds, making them unsuitable for consumption. By utilizing seaweed biomass, this study addresses critical marine environmental issues and provides a sustainable solution for promising electrode materials for energy storage devices. The fabrication process involved impregnating seaweed with Ni ions, followed by annealing to create a highly crystalline carbon structure. Subsequent etching produced numerous nano-sized pores and a large surface area (806 m2/g), significantly enhancing the number of electrically active sites. The resulting HGCs exhibited a high capacitance and maintained their capacity even after 10,000 cycles in fast-current systems. This innovative approach not only mitigates the environmental burden of seaweed waste but also offers a sustainable method for converting it into efficient energy storage materials. [ABSTRACT FROM AUTHOR]

Solid blend polymer electrolytes are prepared(SBPE) comprising poly(ethylene oxide), poly(vinylidene fluoride-co-hexafluoro propylene), and different wt% of ammonium bromide (NH4Br) salt using solution casting approach. The structure, morphology, and chemical bond formation within the prepared polymer electrolytes are confirmed utilizing techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The sample with least degree of crystallinity has higher ionic conductivity of 2.55 × 10−4 S cm−1 at 303 K temperature. The transference numbers of ions (tions) (tions) and electrons (tele) (tele) are found to be 0.9978 and 0.0022 accordingly. The linear sweep voltammetry(LSV) demonstrates that the potential window of the better conducting polymer electrolyte is 2 V. Cyclic voltammetry (CV) studies confirm that there is no redox reaction in the polymer electrolytes and scan rate influences specific capacitance. The values of specific capacitance, energy density, and power density of fabricated electric double-layer capacitor (EDLC) are 8.12 F g−1, 1.12 Wh kg−1, and 125 W kg−1, respectively. [ABSTRACT FROM AUTHOR]

Miniaturized energy storage devices, such as electrostatic nanocapacitors and electrochemical micro-supercapacitors (MSCs), are important components in on-chip energy supply systems, facilitating the development of autonomous microelectronic devices with enhanced performance and efficiency. The performance of the on-chip energy storage devices heavily relies on the electrode materials, necessitating continuous advancements in material design and synthesis. This review provides an overview of recent developments in electrode materials for on-chip MSCs and electrostatic (micro-/nano-) capacitors, focusing on enhancing energy density, power density, and device stability. The review begins by discussing the fundamental requirements for electrode materials in MSCs, including high specific surface area, good conductivity, and excellent electrochemical stability. Subsequently, various categories of electrode materials are evaluated in terms of their charge storage mechanisms, electrochemical performance, and compatibility with on-chip fabrication processes. Furthermore, recent strategies to enhance the performance of electrode materials are discussed, including nanostructuring, doping, heteroatom incorporation, hybridization with other capacitive materials, and electrode configurations. [ABSTRACT FROM AUTHOR]

This study used a scalable process to fabricate activated carbon (AC) supercapacitor electrodes with cornstarch as a green binder. A vital aspect of this study was comparing its performance with synthetic binders like polyvinylidene fluoride (PVDF) and Nafion. The chemical and physical properties of the AC were characterized using Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and Field Emission Scanning Electron Microscopy (FE-SEM). Water contact angle measurements evaluated the hydrophilicity of AC-based electrodes with different binders. Their electrochemical characteristics were studied using open circuit potential (OCP), cyclic voltammetry (CV), galvanic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1 M NaSO4 electrolyte, and the charge storage mechanism was discussed in detail. The starch binder significantly facilitated the charge storage mechanism by suppressing diffusion limitations compared to other binders. The fabricated symmetric supercapacitor device of starch-based electrodes exhibited the highest Cs of 120 F/g at a specific current of 1 A g-1 with a high energy density of 135 Wh/kg and an exact power density of 750 W/kg. The starch-based supercapacitor device exhibited a capacitance retention of 104 % and 65.5 % at specific currents of 2 A g-1 and 10 A g-1 after 10,000 cycles of charging/discharging, respectively.

Abstract In this work, new plasticized solid polymer electrolytes (SPEs) are developed using MC (methylcellulose) as a polymer host, and sodium iodide (NaI) as a dopant via the solution casting method. Ethyl carbonate (EC) is used as a plasticizing agent to improve the properties of the SPEs. Polarized optical microscopy analysis reveals that the surface morphology of the MC‐NaI‐EC films contained porous amorphous regions owing to the presence of EC. The complex formation between MC, NaI, and EC is confirmed by Fourier‐transform infrared spectra. The addition of EC in the MC‐NaI polymer salt matrix enhances the electrochemical properties of the prepared films. The highest ionic conductivity of 5.06×10−3 S/cm is achieved for the composition: MC+50 wt. % NaI +10 wt. % EC. The linear sweep voltammetry test reveals that the optimal plasticized‐SPE can withstand up to 2.5 V. The ionic transference number analysis reveals that 99% of ions contribute to the total conductivity. The optimized SPE film and graphene oxide‐based electrodes are used to manufacture a solid‐state electrical double‐layer capacitor. The coulomb efficiency of the supercapacitor cell is 100%, and the specific capacitance of the supercapacitor is found to be 18.56 F/g utilizing impedance data at low frequency.

This work explores the synthesis and energy applications of the novel hetero-system based on (cerium/praseodymium/neodymium)-oxides doped titanium dioxide (Ce/Pr/Nd)3+-doped TiO 2). With the narrow band gap energy spanning over the range of 3.62–3.89 eV, this semiconductor acquired anatase phase and average crystallite size of 77.41 nm. Rare earths triply doped TiO 2 exhibited bi-functionality towards production of O 2 an H 2 via oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Lowest overpotential (OER: 140 mV and HER: 135 mV) and Tafel slopes (OER: 69.1 mV dec−1 and HER: 57.2 mV dec−1) reflected the efficiency of this material for energy generation. Furthermore, Ce/Pr/Nd)3+-doped TiO 2 is an excellent electrode material exhibiting electrical double layer capacitance (EDLC) with specific capacity of 749 F g−1 and a lower equivalent series resistance (Rs) of 0.12 Ω. In terms of photovoltaic applications, 16.71% efficient perovskite solar cell device containing Ce/Pr/Nd)3+-doped TiO 2 as an electron transport layer was fabricated that was fully functional at the ambient conditions. The developed material possessed commendable band gap alignment with the perovskite material resulting in higher efficiency. Lanthanide doped TiO 2 is an efficient, easy to prepare, sustainable, and cost effective option having potential to substitute costly energy materials. [Display omitted] • Semiconductor (Ce/Pr/Nd)3+-doped TiO 2 hetero-system synthesis. • Energy generative bifunctional catalyst for OER/HER. • Electrical double layer capacitance with excellent storage potential. • Electron transport layer in perovskite solar cells. • Highly durable and electrochemically stable material. [ABSTRACT FROM AUTHOR]

The current study aims to develop a unique approach for constructing an asymmetric supercapacitor utilizing a nanocomposite of MgO-carbon as electrode material. The geometrical surface area of the MgO-carbon has shown to be highly porous with different porosities, and the value is 210 m2g−1. This supercapacitor operates with an aqueous electrolyte consisting of 1 M KOH. The findings indicate that the test cell exhibited exceptional electrochemical output within the voltage range of 0 to 1 V. The capacitance of the MgO-carbon cell is measured to be 225 F g−1 at a current density of 2 A g−1. According to research on cycling, the aforementioned cell has demonstrated the ability to maintain 97% of its original capacitance following 20,000 cycles. The findings of this study suggest that the MgO-carbon holds promise as an electrode material for the development of environmentally friendly and cost-effective energy storage devices. This composite exhibit excellent energy and power densities, along with a prolonged cycle life. [ABSTRACT FROM AUTHOR]

In large-scale all-solid-state storage technologies, solid polymer electrolytes (SPEs) provide greater safety and longer cycle life than traditional liquid or gel polymer electrolytes. Polymer electrolytes (PEs) derived from biopolymers have been intensively explored for use in electrochemical devices due to their great flexibility, low cost, and environmental sustainability. However, biopolymer-based electrolytes cannot meet the expectations of practical applications at room temperature due to their low ionic conductivity. Over the years, improving the performance of this class of electrolytes has been the focus of intense research and development, notably polymer blending, plasticization, and structural functionalization. Here, we investigate the performance of an all-biopolymer solid electrolytes based on a methylcellulose-pectin blend doped with potassium phosphate. FESEM micrographs, as well as the shifting and changing intensity of FTIR bands in the electrolyte specimens confirm the polyblend homogeneity with no phase separation. The increased amorphous fraction of the composite polymer electrolytes (CPEs) is seen in the XRD and DSC patterns of the plasticized and unplasticized samples. Impendence studies performed on the system recorded a maximum ionic conductivity of 1 × 10–5 Scm−1 by doping with 50 wt.% K3PO4. This value further increased to 5.9 × 10–4 Scm−1 upon adding 25 wt.% EC to the polymer system. This sample also possesses an electrochemical stability window of 4.24 V and an ion transference number of 0.95. [ABSTRACT FROM AUTHOR]

Nickel oxide nanoparticles (NiO NPs) are synthesized using olive leaf extract (OLE), which contains a range of polyphenols. These polyphenols serve as both reducing and capping agents, stabilizing the nanoparticles. Aqueous nickel acetate is employed as a precursor. Simultaneously, exfoliated graphene (EG) is obtained via electrochemical exfoliation of graphite in aqueous solutions. These materials were employed as electroactive components in supercapacitor applications. Characterization of NiO and EG involved thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and scanning/transmission electron microscopy (SEM/TEM), alongside Brunauer−Emmett−Teller (BET) analysis, confirming the formation of crystalline NiO NPs with a cubic phase and Fm-3m space group. Micrographs revealed nanoscale dimensions for both NiO and EG with a substantial surface area, as verified by BET analysis. Symmetric (NiO/NiO, EG/EG) and asymmetric (NiO/EG) supercapacitors were fabricated using the doctor blade method. Electrode evaluation, employing field-emission scanning electron microscopy FESEM, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), demonstrated promising morphological and electrochemical characteristics. At low scan rates, both symmetric and asymmetric supercapacitors exhibited a notable gravimetric capacitance (221, 111, and 162 F g–1 at 1 mV s–1). Additionally, they revealed higher power density (173, 137, and 161 W kg–1 at 10 mV s–1), showcasing pseudocapacitive and electric double-layer capacitor (EDLC) behavior for NiO NPs and EG, respectively. This research significantly contributes valuable insights by presenting a sustainable synthesis route for NiO NPs, developing high-performance supercapacitor electrodes, and achieving a comprehensive understanding of the electrochemical behavior of NiO NPs and EG. [ABSTRACT FROM AUTHOR]

Abstract Aging processes occurring in electrical double layer capacitors greatly influence the lifetime of these energy storage devices and an increasing attention has been directed toward their understanding. While most studies approach this topic based on the overall electrochemical performance of the cell (such as enhanced resistance) or the materials degradation, addressing its failure causes at the electrolyte level is of great importance. Doing so, more precise strategies to improve the lifetime and performance can be developed for a wide range of applications. This article provides an overview of the current state of separation tools regarding gas chromatography and detection tools in various combinations with mass spectrometry. The aim of this work is to present the present state of the current knowledge on aging processes, with a focus on gas chromatography and mass spectrometry. Then, an outlook onto the challenges as well as ideas of combining methods is given. Here, the work offers a judgement into future challenges.

The present study reports the synthesis, characterization, and application as energy devices of an ionic liquid blended polymer electrolyte film in which the host polymer polyvinyl alcohol (PVA) is mixed with low viscosity ionic liquid (IL) 1-ethyl-3-methylimidazolium thiocyanate. Various characterization tools have been used further to elaborate electrical, structural, and photoelectrochemical properties. X-ray diffraction (XRD) and polarized optical microscope (POM) affirm the reduction of crystallinity of polymer, while Fourier transform infrared spectroscopy (FTIR) shows complexation and composite nature. Electrochemical impedance spectroscopy shows an enhancement in ionic conductivity by IL doping, where the highest conductivity is achieved at 60 wt% of IL concentration with a conductivity value of 6.21 × 10⁻⁴ S/cm. The ionic transference number (tion) and electrochemical stability measurement show the film's predominantly ionic nature and a reasonable stability window. Using maximum conducting film sandwiched between electrodes, we have successfully fabricated two devices, i.e., an electrical double-layer capacitor (EDLC) and a dye-sensitized solar cell (DSSC). The fabricated EDLC capacitor shows a specific capacitance of 125 F/g, while DSSC shows an efficiency of 1.1 % at one sun condition.

The aim of this study is to address the growing concern about microplastics in the ocean and their potential harm to human health through ingestion. The MPs issue is largely a result of the increasing demand for electronic devices and their components. To tackle this challenge, the research aimed to develop a green polymer electrolyte that used glycerol as a plasticizing agent to improve ionic conductivity. The polymer host included chitosan and polyvinyl alcohol and was composed of sodium acetate. To evaluate the performance of the polymer electrolyte, various analytical techniques were used, including impedance and electrochemical studies. The ionic conductivity of 7.56 × 10−5 S·cm−1 was recorded. The dielectric property study confirmed the ionic conduction process in the system and revealed the existence of non-Debye type relaxation, as indicated by asymmetric peaks of tanδ spectra. The alternating conductivity exhibits three distinguished regions. The polymer electrolyte was discovered to be electrochemically stable up to 2.33 V and capable of storing energy as a non-Faradaic electrochemical double-layer capacitor (EDLC). The cyclic voltammetry pattern is a leaf like shape. The EDLC was able to be charged and discharged up to 1 V, and it showed cyclability and could be used in low-voltage applications.

In this study, a three-dimensional (3D) interconnected porous Ni/SiC skeleton (3D Ni/SiC) was synthesized by binder-free hydrogen bubble template-assisted electrodeposition in an electrolyte containing Ni2+ ions and SiC nanopowders. This 3D Ni/SiC skeleton served as a substrate for directly synthesizing nickel–cobalt layered double hydroxide (LDH) nanosheets via electrodeposition, allowing the formation of a nickel–cobalt LDH nanosheet-decorated 3D Ni/SiC skeleton (NiCo@3D Ni/SiC). The multiscale hierarchical structure of NiCo@3D Ni/SiC was attributed to the synergistic interaction between the pseudocapacitor (3D Ni skeleton and Ni–Co LDH) and electrochemical double-layer capacitor (SiC nanopowders). It provided a large specific surface area to expose numerous active Ni and Co sites for Faradaic redox reactions, resulting in an enhanced pseudocapacitance. The as-fabricated NiCo@3D Ni/SiC structure demonstrated excellent rate capability with a high areal capacitance of 1565 mF cm−2 at a current density of 1 mA cm−2. Additionally, symmetrical supercapacitor devices based on this structure successfully powered commercial light-emitting diodes, indicating the potential of as-fabricated NiCo@3D Ni/SiC in practical energy storage applications.

An ongoing challenge in the field of supercapacitors revolves around comprehending their failure mechanisms. The aging processes occurring at the electrode/electrolyte interphase of these devices are complex. Thus far, much attention has been directed toward examining the aging of electrodes, while fewer studies have been dedicated to the electrolyte's aging. This study aims to address this point and to gain a deeper understanding of the importance of individual decomposition products on the overall decomposition of the electrolytic solution of electric double‐layer capacitors. Therefore, the decomposition of the state‐of‐the‐art electrolyte 1 m solution of tetraethylammonium‐tetrafluoroborate in acetonitrile and that of the same electrolyte doped with compounds known to form during its aging, such as acetamide, 2,4,6‐trimethyl‐1,3,5‐triazine, and triethylamine has been investigated post‐mortem. The results of this study show that GC‐MS is a useful technique to interpret and understand the degradation processes taking place in the electrolytes of supercapacitors. [ABSTRACT FROM AUTHOR]

To date, batteries are the most widely used energy storage devices, fulfilling the requirements of different industrial and consumer applications. However, the efficient use of renewable energy sources and the emergence of wearable electronics has created the need for new requirements such as high-speed energy delivery, faster charge–discharge speeds, longer lifetimes, and reusability. This leads to the need for supercapacitors, which can be a good complement to batteries. However, one of their drawbacks is their lower energy storage capability, which has triggered worldwide research efforts to increase their energy density. With the introduction of novel nanostructured materials, hierarchical pore structures, hybrid devices combining these materials, and unconventional electrolytes, significant developments have been reported in the literature. This paper reviews the short history of the evolution of supercapacitors and the fundamental aspects of supercapacitors, positioning them among other energy-storage systems. The main electrochemical measurement methods used to characterize their energy storage features are discussed with a focus on their specific characteristics and limitations. High importance is given to the integral components of the supercapacitor cell, particularly to the electrode materials and the different types of electrolytes that determine the performance of the supercapacitor device (e.g., storage capability, power output, cycling stability). Current directions in the development of electrode materials, including carbonaceous forms, transition metal-based compounds, conducting polymers, and novel materials are discussed. The synergy between the electrode material and the current collector is a key factor, as well as the fine-tuning of the electrode material and electrolyte. [ABSTRACT FROM AUTHOR]

Amidst different types of energy storage systems, electrochemical supercapacitors have received considerable attention as they close the gap between electrolytic capacitors and batteries. This work addresses electric double-layer capacitors (EDLCs), a type of electrochemical supercapacitor, and has been divided into two parts. In the former, the synthesis and characterization of activated carbon fiber-felt (ACFF) electrodes, derived from textile PAN-based fiber, have been provided. In the latter, the electrochemical characterization of EDLCs in potassium hydroxide solutions (aqueous electrolytes) and in potassium hydroxide-glycerol hybrid electrolytes (glycerol-based electrolytes) have been investigated. The synthesis of ACFF electrodes via two-step oxidation, carbonization, and physical activation resulted in low-cost and binder-free electrodes containing 87% of the total volume of pores as micropores (maximum pore width of 3 nm) and a high specific surface area of 1875 m2 g−1. Electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge–discharge techniques were carried out in a symmetric two-electrode setup at room temperature. The results showed that ACFF electrodes are suitable for aqueous electrolytes, particularly 2 M KOH, and KOH:GLY (3:1), a glycerol-based electrolyte. Although KOH:GLY (3:1) exhibited high electrolyte resistance (34 ± 3 Ω), this hybrid green-electrolyte supports a potential window that is twice greater than that of aqueous electrolytes. In addition, glycerol, commonly called glycerin, is a by-product of FAME (fatty acid methyl ester) biodiesel, which is the major source of glycerol. Glycerol-based electrolytes are promising green electrolytes for EDLCs. Therefore, it is necessary to decrease its viscosity and resistance. [ABSTRACT FROM AUTHOR]

There has been considerable interest in supercapacitors because of their remarkable advantages, including their high power density, rapid charge–discharge rate, and long cycle life. Metal–organic frameworks (MOFs) have been extensively utilized in energy conversion and storage due to their large specific surface area and tunable pore structures. The poor conductivity of MOFs makes them unsatisfactory electrode materials for supercapacitors. This issue was addressed by synthesizing graphene-supported Zn-BTC metal–organic framework materials with different morphologies by combining ultrasonic oscillation with one-step solvothermal synthesis. It was found that the synthesized Zn-BTC material was uniformly anchored on wrinkled graphene nanosheets and that the specific capacitance was 201.3 C g−1 (at 1 A g−1), exceeding the specific capacitance of graphene-supported two-dimensional sheet-like Zn-BTC (152.6 C g−1), graphene-supported three-dimensional spherical Zn-BTC (139.6 C g−1), graphene (108.2 C g−1), and one-dimensional rod-shaped Zn-BTC (63.5 C g−1). Using graphene-supported, rod-shaped Zn-BTC as a basis for symmetric supercapacitors, a maximum energy density of 4.55 Wh kg−1 was achieved at 104.17 W kg−1 with specific capacitance retention of 93.26% after 2000 charge–discharge cycles at a current density of 1 A g−1. [ABSTRACT FROM AUTHOR]

AbstractMicroplastic and metal waste from electronic industries are becoming a major threat to the environment and marine ecosystem. Green processing and employing natural derived materials are solutions to this issue. In this work, an electrical double-layer capacitor (EDLC) fabricated from green polymer electrolyte (GPE) sandwiched in between two microbial cellulose-based electrodes is characterized. The eco-friendly electrode films of interconnected cellulose and multiwalled carbon nanotube (MWCNT) are obtained via harmless, inexpensive, and simple procedure. The GPE consists of methylcellulose-potato starch blend as polymer blend and ammonium iodide (NH4I) is chosen as ion provider. Glycerol serves as plasticization agent for alternative pathways enabling ionic migration. The most optimum GPE possesses good ionic conductivity of ∼ 10−3 S/cm. Ions are the dominant charge carrier in the GPE as ion transference number shown to be close to unity. Linear sweep voltammetry (LSV) analysis illustrated that the GPE is electrochemically stable up to 2.4 V. The green EDLC stores energy through non-Faradaic mechanism and the specific capacitance from charge-discharge, Ccd is influenced by the sweep rates. The EDLC can be charged and discharged up to 2 V with a stable 1000 cyclability performance. This work implied the potential of microbial cellulose-based EDLC as ideal green-based energy storage device for low voltage applications such as smart electronic textiles.

Carbon is a fundamental material in developing electrochemical double-layer capacitors (EDLCs), also known as supercapacitors. Many studies have proven the impact of various carbon material properties, such as surface area, pore volume, and chemical surface composition, on the specific capacitance of supercapacitors (EDLCs). However, research endeavors to comprehensively evaluate the contribution of these material properties in correlation with experimental parameters, such as electrolyte concentration, voltage window, and current density, are scarce. This study aimed to employ machine learning algorithms to comprehend the interdependence between the properties of biomass-based carbon and the aforementioned experimental parameters with the capacitance of EDLCs. Four models of the machine learning algorithms were utilized in this study, including linear regression (LR), M5-Rules, Random Tree (RT), and Multi-Layer Perceptron (MLP), to determine the most suitable algorithm for analyzing and predicting the capacitance of EDLCs. The results revealed that the MLP model exhibited the highest determination correlation coefficient (R) of 0.871 with a Mean Absolute Error (MAE) of 45.069 F/g. Besides, the study utilized a machine learning correlation attribute model and observed that the supercapacitor’s surface area and pore volume demonstrated significant correlations with the same correlation ratio of 0.4. In conclusion, these findings emphasize the importance of considering surface area and pore volume in developing and optimizing supercapacitors. Finally, this study adds knowledge in supercapacitors and provides valuable insights for designing and developing high-performance energy storage devices.

Miniaturized energy storage devices, such as electrostatic nanocapacitors and electrochemical micro-supercapacitors (MSCs), are important components in on-chip energy supply systems, facilitating the development of autonomous microelectronic devices with enhanced performance and efficiency. The performance of the on-chip energy storage devices heavily relies on the electrode materials, necessitating continuous advancements in material design and synthesis. This review provides an overview of recent developments in electrode materials for on-chip MSCs and electrostatic (micro-/nano-) capacitors, focusing on enhancing energy density, power density, and device stability. The review begins by discussing the fundamental requirements for electrode materials in MSCs, including high specific surface area, good conductivity, and excellent electrochemical stability. Subsequently, various categories of electrode materials are evaluated in terms of their charge storage mechanisms, electrochemical performance, and compatibility with on-chip fabrication processes. Furthermore, recent strategies to enhance the performance of electrode materials are discussed, including nanostructuring, doping, heteroatom incorporation, hybridization with other capacitive materials, and electrode configurations.

Abstract An ongoing challenge in the field of supercapacitors revolves around comprehending their failure mechanisms. The aging processes occurring at the electrode/electrolyte interphase of these devices are complex. Thus far, much attention has been directed toward examining the aging of electrodes, while fewer studies have been dedicated to the electrolyte's aging. This study aims to address this point and to gain a deeper understanding of the importance of individual decomposition products on the overall decomposition of the electrolytic solution of electric double‐layer capacitors. Therefore, the decomposition of the state‐of‐the‐art electrolyte 1 m solution of tetraethylammonium‐tetrafluoroborate in acetonitrile and that of the same electrolyte doped with compounds known to form during its aging, such as acetamide, 2,4,6‐trimethyl‐1,3,5‐triazine, and triethylamine has been investigated post‐mortem. The results of this study show that GC‐MS is a useful technique to interpret and understand the degradation processes taking place in the electrolytes of supercapacitors.

Microplastic and metal waste from electronic industries are becoming a major threat to the environment and marine ecosystem. Green processing and employing natural derived materials are solutions to this issue. In this work, an electrical double-layer capacitor (EDLC) fabricated from green polymer electrolyte (GPE) sandwiched in between two microbial cellulose-based electrodes is characterized. The eco-friendly electrode films of interconnected cellulose and multiwalled carbon nanotube (MWCNT) are obtained via harmless, inexpensive, and simple procedure. The GPE consists of methylcellulose-potato starch blend as polymer blend and ammonium iodide (NH4I) is chosen as ion provider. Glycerol serves as plasticization agent for alternative pathways enabling ionic migration. The most optimum GPE possesses good ionic conductivity of ∼ 10−3 S/cm. Ions are the dominant charge carrier in the GPE as ion transference number shown to be close to unity. Linear sweep voltammetry (LSV) analysis illustrated that the GPE is electrochemically stable up to 2.4 V. The green EDLC stores energy through non-Faradaic mechanism and the specific capacitance from charge-discharge, Ccd is influenced by the sweep rates. The EDLC can be charged and discharged up to 2 V with a stable 1000 cyclability performance. This work implied the potential of microbial cellulose-based EDLC as ideal green-based energy storage device for low voltage applications such as smart electronic textiles. [ABSTRACT FROM AUTHOR]

The investigated starch biopolymer membrane was found to be a sustainable alternative to currently reported and used separators due to its properties, which were evaluated using physicochemical characterization. The molecular dynamics of the biomembrane were analyzed using low-field nuclear magnetic resonance (LF NMR) as well as Raman and infrared spectroscopy, which proved that the chemical composition of the obtained membrane did not degrade during microwave-assisted polymerization. Easily and cheaply prepared through microwave-assisted polymerization, the starch membrane was successfully used as a biodegradable membrane separating the positive and negative electrodes in electric double-layer capacitors (EDLCs). The obtained results for the electrochemical characterization via cyclic voltammetry (CV), galvanostatic charge with potential limitation (GCPL), and electrochemical impedance spectroscopy (EIS) show a capacitance of 30 F g−1 and a resistance of 2 Ohms; moreover, the longevity of the EDLC during electrochemical floating exceeded more than 200 h or a cyclic ability of 50,000 cycles. Furthermore, due to the flexibility of the membrane, it can be easily used in novel, flexible energy storage systems. This proves that this novel biomembrane can be a significant step toward ecologically friendly energy storage devices and could be considered a cheaper alternative to currently used materials, which cannot easily biodegrade over time in comparison to biopolymers. [ABSTRACT FROM AUTHOR]

The growing demand for environmentally friendly materials in energy storage has led to a significant focus on using biopolymer membranes derived from renewable resources. This study focuses on creating eco-friendly biopolymer electrolytes for Electric Double Layer Capacitors (EDLC) by blending Magnesium trifluoromethanesulfonate (Mg(CF3SO3)2) with Cellulose Acetate (CA) through a solution casting method. To enhance performance, plasticized membranes were developed using nontoxic Poly(ethylene glycol) (PEG) as a plasticizer. The addition of PEG reduced membrane crystallinity, as shown by X-ray diffraction (XRD). Fourier Transform Infrared (FTIR) spectroscopy indicated complexation among electrolyte constituents. The optimal composition, containing 25 wt% PEG, exhibited the highest ion conductivity (3.76 × 10−4 S/cm) according to Electrochemical Impedance Spectroscopy (EIS). EIS data allowed determination of important ion transport parameters, such as Diffusion Coefficient, Ionic Mobility, and Carrier Density. The EDLC device showed a Specific Capacitance (Csp) of 13.14 F/g at a scan rate of 5 mV/s, with excellent stability (3.2 V) in Linear Sweep Voltammetry (LSV). Cyclic Voltammetry (CV) and Galvanostatic Charge Discharge (GCD) tests confirmed no redox processes, yielding a Csp of 12.94 F/g at 0.1 A/g. The EDLC device demonstrated exceptional cyclic stability, high coulombic efficiency, and maintained consistent results in terms of Power Density (Pd) and Energy Density (Ed) over 1000 cycles. Incorporating PEG into biopolymer membranes enhances the electrochemical energy storage of EDLC devices, contributing to sustainable energy storage solutions.

Magnesium ion conducting biodegradable polymer blend electrolytes are prepared by solution casting technique with double distilled water as solvent. Here, Chitosan, Poly-vinyl alcohol (PVA) are used as host polymers and Magnesium chloride (MgCl2) as dopant salt. The prepared electrolytes are characterized with different characterization techniques like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Electrochemical impedance spectroscopy (EIS) and Differential scanning calorimetry (DSC). The crystallinity/amorphous nature of the electrolytes are determined by XRD. FTIR is used to confirm the complexation formation between the host polymers and salt. The Chitosan:PVA:MgCl2 polymer electrolyte shows maximum ionic conductivity of 5.9 × 10−5S/cm obtained from electrochemical impedance spectroscopy analysis. The thermal stability and glass transition temperature of electrolytes are studied using differential scanning calorimeter (DSC). The higher conducting polymer electrolyte is used to fabricate an electric double layer capacitor(EDLC) and it's performance is tested. [ABSTRACT FROM AUTHOR]

The presented work discusses in detail the preparation of a cheap and environmentally friendly biopolymer membrane from isinglass and its physicochemical characterisation. One of the possible uses of the obtained membrane can be as a separator between electrodes in novel green electrochemical devices as in, for example, electric double-layer capacitors (EDLCs). The functionality of the mentioned membrane was investigated and demonstrated by classical electrochemical techniques such as cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), and electrochemical impedance spectroscopy (EIS). The obtained values of capacitance (approximately 30 F g−1) and resistance (approximately. 3 Ohms), as well as the longevity of the EDLC during electrochemical floating at a voltage of 1.6 V (more than 200 h), show that the proposed biopolymer membrane could be an interesting alternative among the more environmentally friendly energy storage devices, while additionally it could be more economically justified. [ABSTRACT FROM AUTHOR]

Porous carbon electrode materials are utilized in supercapacitors with very fast charge/discharge and high stability upon cycling thanks to their electrostatic charge storage mechanism. Further enhancement of the performance of such materials can be achieved by doping them with heteroatoms which alter the kinetics of charge/discharge of the adsorbed species and result in pseudocapacitance phenomena. Here, microporous N-doped activated carbons were synthesized by thermochemical activation process. The structure and composition of the final material were adjusted by tuning the synthesis conditions and the choice of precursor molecules. In particular, N-doped activated carbons with a controlled specific surface area in the range of 270–1380 m2/g have been prepared by KOH-activation of sucrose/ammonium citrate mixture. By adjusting the composition of precursors, N-doping was varied from ca. 1.5 to 7.3 at%. The role of the components and synthesis conditions on the composition and structure of final products has been evaluated. The N-doped activated carbon with optimized structure and composition has demonstrated an outstanding performance as electrode material for aqueous electrolyte supercapacitors. The specific capacitance measured in a 3-electrode cell with 0.75 mg/cm2 loading of optimized activated carbon in 1M H2SO4 changed from 359 F/g at 0.5 A/g charging rate to 243 F/g at 20 A/g. Less than 0.01% of capacitance loss has been detected after 1000 charging/discharging cycles. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte based on poly (ethyl methacrylate) (PEMA) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was prepared for electrochemical double-layer capacitor (EDLC) application. Incorporation of 50 wt% LiTFSI elevated the ionic conductivity by five orders of magnitude from (4.64 ± 0.01) × 10–11 to (1.22 ± 0.01) × 10–6 S cm−1. The doping of LiTFSI also improved the thermal stability of the polymer electrolyte from 331 to 384 ºC. Moreover, structural information from FTIR suggested that Li+ can interact with oxygen of carbonyl and ester groups of PEMA. Linear sweep voltammetry (LSV) showed that there is an improvement on the electrochemical stability window from 2.2 to 3.2 V upon addition of 40 and 50 wt% of LiTFSI. Transference number analysis affirmed that ion is the major contributor to the ionic conductivity of the PEMA-LiTFSI polymer electrolyte system. The fabricated PEMA-LiTFSI-based EDLC cell exhibited specific capacitance of 358.1 m F g−1. The energy density and power density of the PEMA-LiTFSI-based EDLC cell were 22.2 mWh kg−1 and 14.0 W kg−1, respectively. [ABSTRACT FROM AUTHOR]

An ionic liquid (IL) 1-ethyl, 2-methyl imidazolium thiocyanate incorporated biopolymer system is reported in this communication for applications in dual energy devices, i.e., electric double-layer capacitors (EDLCs) and dye-sensitized solar cells (DSSCs). The solution caste method has been used to synthesize ionic-liquid-incorporated biopolymer electrolyte films. The IL mixed biopolymer electrolytes achieve high ionic conductivity up to the order of 10−3 S/cm with good thermal stability above 250 °C. Electrical, structural, and optical studies of these IL-doped biopolymer electrolyte films are presented in detail. The performance of EDLCs was evaluated using low-frequency electrochemical impedance spectroscopy, cyclic voltammetry, and constant current charge–discharge, while that of DSSCs was assessed using J–V characteristics. The EDLC cells exhibited a high specific capacitance of 200 F/gram, while DSSCs delivered 1.53% efficiency under sun conditions. [ABSTRACT FROM AUTHOR]

Botol plastik sekali pakai menduduki urutan kedua dari tipe plastik di dunia termasuk di Indonesia sebagai plastik yang paling banyak digunakan. Hal ini menghadirkan tantangan yang besar dalam hal pengolahan limbahnya. Di sisi lain, karbon aktif merupakan salah satu material yang dapat digunakan sebagai material elektroda dari superkapasitor yang merupakan salah satu media penyimpanan energi listrik yang tersusun atas elektroda dan elektrolit. Penelitian ini digagas untuk mengembangkan karbon aktif yang dihasilkan dari limbah botol plastik sekali pakai yang selanjutnya diaplikasikan sebagai elektroda superkapasitor. Terdapat 2 tahap proses yaitu karbonisasi pada suhu 500°C, 600°C, dan 700°C dan aktivasi. Adapun aktivasi dilakukan dalam 2 tahap secara kimia (menggunakan ZnCl2) dan fisika. Selain itu, penelitian ini menggunakan PVA-K2CO3 dalam bentuk gel sebagai elektrolit superkapasitor. Berdasarkan karakterisasi, material yang dihasilkan merupakan 100% karbon dan telah berhasil teraktivasi. Karbon aktif dari PET dihasilkan merupakan karbon aktif tipe mikropori dengan ukuran volume rata-rata karbon aktif dengan trend kenaikan seiring dengan kenaikan suhu karbonisasi yang digunakan berturut-turut sebesar 0,0362643 cm3/g, 0,0416015 cm3/g dan 0,0450067 cm3/g. Karbon aktif yang dihasilkan telah berhasil diimplementasikan sebagai elektroda pada Electric Double Layer Capasitors (EDLCs) dimana kenaikan suhu karbonisasi yang digunakan berdampak pada turunnya jumlah tegangan yang dapat disimpan oleh EDLCs dengan hasil berturut-turut sebesar 1,227 V, 1,197 V, 1,116 V dengan rentang waktu pengisian daya selama 1 jam.

This study used a physical activation method to prepare asphalt-pitch-derived activated carbon (Pitch AC) for an electric double-layer capacitor (EDLC) electrode. X-ray diffraction analysis and Raman spectroscopy were used to estimate the change in the crystal structure of Pitch AC with activation time. In addition, the textural properties of Pitch AC were studied by Brunauer-Emmett-Teller (BET), Dubinin-Radushkevich (DR) and non-localized density functional theory (NLDFT) equations with N2/77K isotherm adsorption-desorption curves. The electrochemical performance of the Pitch AC was analyzed using a coin-type EDLC with 1 M SBPBF4/PC via galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The specific surface area and total pore volume were 990–2040 m2/g and 0.42–1.51 cm3/g, respectively. The pore characteristics of the Pitch AC varied according to the activation time and changed from a microporous structure to a micro-mesoporous structure as the activation time increased. The electrochemical performance analysis also found that the specific capacity was increased from 43.6 F/g to 84.5 F/g at 0.1 A/g as activation time increased. In particular, Pitch AC-9 exhibited the best electrochemical performance (rectangular CV curve, reversible GCD, lowest ion charge transfer resistance and Warburg impedance). In addition, Pitch AC-9 was confirmed to have a specific capacitance similar to commercial activated carbon for EDLC (YP-50F). Therefore, it was considered that Pitch AC could replace commercial activated carbon for EDLC because it has excellent pore characteristics and electrochemical performance despite being manufactured through a very low-cost precursor and a simple process (physical activation method). [ABSTRACT FROM AUTHOR]

In this work, the activated carbon (AC) is derived from the waste material of peanut shells. The obtained activated carbon has been synthesized using the chemical activation process via impregnation with NaOH at various proportions (1:2 and 1:3). The structural, morphological, and electrochemical properties of obtained AC are examined by X-ray diffraction (XRD), BET surface analysis, scanning electron microscopy (SEM), and electrochemical techniques. The resulting AC shows the enhancement in specific surface area (SSA) from 584 to 735 m2/g at 1:2 ratio and 826 m2/g at 1:3 ratio after the activation process. The electrodes are fabricated using derived activated carbon for electrochemical characterization. It has been observed through cyclic voltammetry and galvanostatic charge–discharge measurements that 1:3 NaOH-activated samples reveal the maximum value of specific capacitance (263 F/g at 10 mV/s and 290 F/gat 0.2A/g). The sample also conveys the pre-dominant ~ 98% of efficiency from 400 to 1000th cycle with fast and almost constant capacitance. The electrochemical impedance spectroscopy (EIS) result suggests the pure capacitive nature of the sample and indicates the dominating electric double-layer capacitive (EDLC) behavior. The obtained results demonstrate that the peanut shell–derived activated carbon is a potential candidate as an electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

A supercapacitor is a type of electrical component that has larger capacitance, due to asymmetric behavior with better power density, and lower ESR (effective series resistance) than conventional energy-storage components. Supercapacitors can be used with battery technology to create an effective energy storage system due to their qualities and precise characterization. Studies have shown that the use of quantum dots as electrodes in supercapacitors can significantly increase their effectiveness. In this research article, we have used a Drude model based on free electrons (asymmetric nature) to describe the supercapacitor's discharging characteristics. Commercially available Nippon DLA and Green-cap supercapacitors were used to verify the Drude model by discharging them through a constant current source using a simple current mirror circuit. The parameters of both the fractional-order models and our suggested method were estimated using the least-squares regression fitting approach. An intriguing finding from the Drude model is the current-dependent behavior of the leakage-parallel resistance in the constant current discharge process. Instead of using the traditional exponential rule, supercapacitors discharge according to a power law. This work reflects the strong symmetry of different aspects of designing a hybrid supercapacitor with high efficiency and reliability. [ABSTRACT FROM AUTHOR]

The large oil palm plantation in Malaysia is located in Sabah which is around 700,000 acres of land that produces around 0.7 million tons of agricultural waste. The conversion of agriculture waste to activated carbon (AC) solves the disposal problem in the agricultural industry. The AC plays an important role as an electrode in supercapacitor due to its characteristics such as high porosity and good conductivity. The performance of supercapacitor electrodes was study by using different sizes of AC. The AC from oil palm kernel shell (PKS) was produced by using the low cost of production with a simple modification in a conventional method. The PKS carbonizes in a furnace at 390 oC for 1 hour. It soaks in KOH for chemical activation. The sample is rushed by using agate mortar to get two different sizes which is fine and coarse. The AC is then mixed for the preparation of the electrode labelled as (Sample 1, Sample 2 & Sample 3). Then, the electrode is assembled with filter paper as separator and 1.0 M KOH as electrolyte. The supercapacitor electrode is connected to the circuit to observe the potential of charge-discharge. The result of capacitance for Sample 1 is 26.3mF, specific capacitance 21.58mF/g and energy density 17.22Wh/kg while the Sample 2 of activated carbon is 2672.38mF, 1113.49 mF/g and energy density 52.384Wh/kg and Sample 3 is 2952.5mF, specific capacitance 1230.16mF/g and energy density 226.34Wh/kg. As conclusion, a high-performance capacitor is achieved by using a mixed size of PKS as active material in electrode. Therefore, PKS has large market potential due to the low-cost AC production but promises high performance in Supercapacitor Application.

The development of multi-functional nanomaterials is nowadays more than a necessity to address both energy and environmental needs of our society. In this perspective, the hybridization of graphene (Gr) with TiO2 nanotubes (TiNT) is very promising to meet these issues. In the present work, bi-functional graphene-modified TiO2 nanotubes electrodes (Gr/TiNT) were successfully prepared. A simple and effective approach for graphene production, by electrochemical exfoliation of pure graphite foil in inorganic salt (Na2SO4) is used. Graphene sheets were formed on the surface of TiO2 nanotube arrays through electrodeposition process by chronoamperometry. Mesoporous graphene of high surface area is promising material for photocatalytic applications. Gr/TiNT electrode displays significantly improved photodegradation efficiency to MB, achieving a degradation percentage of 60% in 2 hours, which is about 50% higher than that of TiNT. Moreover, Gr/TiNT with high conductivity demonstrated good capability to deliver extremely high energy and power in a very short period of time, the relaxation time constant was only about 48 ms, which is far lower than that of most conventional activated carbon-based electrochemical capacitors. Capacitance retention of 98% was also demonstrated after 1000 cycles. [ABSTRACT FROM AUTHOR]

In this study, a new biopolymer electrolyte (BPE) is successfully developed using corn starch complexed with ammonium iodide (NH4I) as host, and low viscosity ionic liquid 1-Ethyl, 3-Methyl Imidazolium Thiocyanate (EMImSCN), as a plasticizer. This ionic liquid doped BPE shows high ionic conductivity of the order 10−4 S/cm and electrochemical stability window more than 3 V, which is suitable for electrochemical application. The ionic transference number (tion) of 0.98 confirms the system to be predominantly ionic in nature. Fourier transform infrared spectroscopy (FTIR) shows complex nature, while polarized optical microscopy (POM) gives us an idea about the semi-crystalline nature of BPE. Maximum conducting ionic liquid doped BPE sandwiched electric double layer capacitor (EDLC) and dye sensitize solar cell (DSSC) shows efficient performance. [ABSTRACT FROM AUTHOR]

In this study, the real‐time increase in pressure of the accumulated gases at the electrode/electrolyte interface serves as a safety criterion for four conductive electrolytes comprising acetonitrile (ACN) and organic salts. They include tetrafluoroborate as an anion and cyclic 1,1‐dimethylpyrrolidinium (Pyr11+), spiro‐(1,1′)‐bipyrrolidinium (SBP+), acyclic methyl triethyl ammonium (Et3MeN+) or standard tetraethylammonium (Et4N+) as cations. The main focus lies on the SPBF4/ACN system. While the concentrated Pyr11BF4/ACN exhibits a minimal pressure evolution (≈25 Pa) under ambient conditions at 3.0 V, its electrochemical stability is inferior to SPBF4 at high operating voltage. The electrolytes with acyclic tetrafluoroborate salts (1.0 mol L−1) reveal a 20‐fold increase in pressure due to the weak salt‐ACN interactions and the subsequent high solvent evaporation. The pressure evolution at the interface of activated carbon/electrolyte in electrochemical double layer capacitor (EDLCs) is merely related to the operating voltage and cation nature, viz. Pyr11+ < SBP+ < Et4N+ < Et3MeN+. The fixed specific capacity of 109 F g−1, volumetric capacity of 76 F cm−3, and moderate gas generation (≈190 Pa at 3.0 V, that shifts to ≈400 Pa at 3.4 V) confirm the safe character of the SPBF4/ACN electrolyte for such energy storage devices. [ABSTRACT FROM AUTHOR]

This work presents a facile and systematic way to prepare low resistive proton conducting biopolymer electrolyte (BPE) membranes from flaxseed gum (FG) via the solution casting technique. Ammonium fluoride (NH 4 F) ionic salt has been added to the FG matrix and optimized the ionic conductivity of the BPE membrane. The structural and morphological investigations were done to comprehend the ion association phenomenon. The enhancement of amorphousity on doping is affirmed by x-ray diffraction (XRD). The complex formation and interactions between FG and proton (H+) have been characterized through fourier transform infrared (FTIR) spectroscopy. The flexibility of the prepared BPE membranes at low glass transition temperature T g was confirmed by differential scanning calorimetry (DSC) thermal analysis. Electrochemical impedance spectroscopy (EIS) shows maximum ionic conductivity of 4.0 × 10‐3 S/cm at FGAF7 composition. The obtained surface topographic images from atomic force microscopy (AFM) confirms that the predominantly uneven amorphous surface with high rms roughness has transformed to a homogenous even surface on the addition of dopant. The TNM findings demonstrated that the ions were the predominant charge carriers. The linear sweep voltammetry (LSV) and cyclic voltammetry (CV) investigations were employed to confirm the electrochemical stability of the BPE membrane. An electrical double layer capacitor (EDLC) has been fabricated using the optimized utmost conducting BPE membrane as an electrolyte and characterized using cyclic voltammetry (CV). These outcomes indicates that the present electrolyte shows promising performance for application in energy storage devices. [ABSTRACT FROM AUTHOR]

• SPE based on NaCMC-PVA complexed with NaClO 4 was developed. • Electrochemical properties were studied as a function of dopant concentration. • Scaling studies indicate a collapsed master curve, suggesting adherence to TTSP. • The EDLC shows specific capacitance (C sp) value of 33.1 F/g @ 0.2 mA/g. • The first cycle energy density is 15.18 W/kg and power density is 4512.5 Wh/kg. Biopolymer-based blends of solid electrolytes capable of conducting sodium ions were prepared via solution casting by incorporating sodium carboxymethyl cellulose (NaCMC) and polyvinyl alcohol (PVA) with varying concentrations of sodium perchlorate monohydrate (NaClO 4.H 2 O), which was used as the dopant. The prepared electrolytes were characterized to reveal their structural, vibrational, electrical, and electrochemical properties that make them promising as solid polymer electrolytes (SPEs). X-ray diffraction (XRD) analysis showed that the amorphous nature of the sample increased with the addition of NaClO 4.H 2 O salt concentrations of up to 30 wt.%. The complexation between the polymers and salt was confirmed by Fourier-Transform Infrared (FTIR) analysis. The SPE exhibited an optimal ionic conductivity of (1.90 ± 0.05) ×10−5 S cm−1, which is three orders higher than that of the pristine polymer blend with (5.31 ± 0.61) ×10−8 S cm−1, as determined by electrochemical impedance spectroscopy (EIS) analysis. Scaling studies conducted based on AC conductivity and tangent loss revealed that these measurements could be represented by a single master curve, which suggests that the optimal sample adheres to the time-temperature superposition principle (TTSP). The temperature dependence of Jonscher's exponent indicates that the conduction mechanism can be effectively represented by the Quantum Mechanical Tunneling model (QMT). Both transference number measurement (TNM) and linear sweep voltammetry (LSV) analyses validated the electrolyte's suitability for energy device applications by demonstrating its high ion transference number and electrochemical potential window of 3.93 V. The optimized SPE film was subsequently utilized in an electrochemical double-layer capacitor (EDLC) device to evaluate its performance as both an electrolyte and separator. The supercapacitor exhibited an impressive energy density of 15.18 Wh kg−1 and a power density of 4512.5 W kg−1, along with remarkable stability in terms of cycle life. [Display omitted] [ABSTRACT FROM AUTHOR]

• Leveraging locally available biomass (Mesua ferrea) as raw material for supercapacitor applications. • N-doped activated carbon was synthesized through pyrolysis at 700 °C and 800 °C. • Prepared electrode material without commercial carbon black, highlighting the efficacy of the biomass-derived carbon. • Achieved a capacitance of 210 f g⁻¹, comparable to commercial activated carbon. • Bio-waste as a viable candidate for future energy utilities. Developing a high energy density supercapacitor is of great challenge due to the low surface area of commercial activated carbon. The present work aims at developing highly porous nitrogen-doped porous carbon from biomass for supercapacitors. Herein, Mesua ferrea (Nahor) shells, a widely available biomass in northeast India, was used to prepare porous carbon. The effect of activation temperature on structural, textural properties, and electrochemical performance is studied. The carbonization temperature highly influenced the pore structure, porosity, surface area, and thereby influencing the electrochemical performance. The porous carbon pyrolyzed at 700 °C delivered a high specific capacitance of 210 F g-1 at 1 A g-1, higher than porous carbon made at higher temperature (27.5 F g-1 at 1 A g-1 for carbon pyrolyzed at 800 °C). The results provide insights that will be of use in the development of high-energy-density capacitors employing biomass-derived porous carbon. [Display omitted] [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon CMK-1 was prepared via carbonization at a relatively low temperature (the first step) followed by partial graphitization (the second step of carbonization at higher temperature) inside the ordered mesopores of cobalt-loaded mesoporous silica MCM-48 using polyacrylonitrile (PAN) as a carbon/nitrogen source. This first step of the carbonization is called "infusibilization", and the resultant material is denoted as PAN inf. In an advanced temperature-programmed desorption analysis of the PAN inf /MCM-48 composite, the temperature of the observed HCN signal indicated that carbonization was reduced from 550 to 450 °C by a Co catalyst. The amount of typical N 2 formation associated with the selective removal of pyridinic N species, resulting in the graphitic surface formation, also increased at a relatively high temperature (approximately 1000 °C) with the aid of the Co catalyst. The CMK-1 prepared through cobalt-catalyzed carbonization exhibited a higher electric double-layer capacitance with an Et 4 N+BF 4 –/propylene carbonate electrolyte, and higher electrical conductivity than CMK-1 prepared without a catalyst. This also implied the progress of graphitization within the carbonaceous wall. These results suggest that the edge planes of the graphitic domains in CMK-1 are predominantly exposed on the surfaces of the carbonaceous walls, resulting in an increase in the number of adsorptive sites for the electrolyte during capacitance measurements. [Display omitted] • CMK-1 obtained from polyacrylonitrile via cobalt-catalyzed carbonization showed a higher electric double-layer capacitance. • The advanced TPD and XPS analyses revealed the selective removal of pyridinic-N species during the carbonization from PAN. • Cobalt catalyst enhances the selective removal of pyridinic-N at 1000 °C. [ABSTRACT FROM AUTHOR]

Abstract In this study, the real‐time increase in pressure of the accumulated gases at the electrode/electrolyte interface serves as a safety criterion for four conductive electrolytes comprising acetonitrile (ACN) and organic salts. They include tetrafluoroborate as an anion and cyclic 1,1‐dimethylpyrrolidinium (Pyr11+), spiro‐(1,1′)‐bipyrrolidinium (SBP+), acyclic methyl triethyl ammonium (Et3MeN+) or standard tetraethylammonium (Et4N+) as cations. The main focus lies on the SPBF4/ACN system. While the concentrated Pyr11BF4/ACN exhibits a minimal pressure evolution (≈25 Pa) under ambient conditions at 3.0 V, its electrochemical stability is inferior to SPBF4 at high operating voltage. The electrolytes with acyclic tetrafluoroborate salts (1.0 mol L−1) reveal a 20‐fold increase in pressure due to the weak salt‐ACN interactions and the subsequent high solvent evaporation. The pressure evolution at the interface of activated carbon/electrolyte in electrochemical double layer capacitor (EDLCs) is merely related to the operating voltage and cation nature, viz. Pyr11+ < SBP+ < Et4N+ < Et3MeN+. The fixed specific capacity of 109 F g−1, volumetric capacity of 76 F cm−3, and moderate gas generation (≈190 Pa at 3.0 V, that shifts to ≈400 Pa at 3.4 V) confirm the safe character of the SPBF4/ACN electrolyte for such energy storage devices.

Supercapacitors became more and more important recently in the area of energy storage and conversion. Their large power deliveries abilities, high stability and environmental friendliness characteristics draw tremendous attention in high-power applications such as public transit networks. Carbonaceous materials with unique surface and electrochemical properties were widely used in supercapacitors as electrode materials. This review focuses on the developments in supercapacitor electrodes made from carbonaceous materials recently, their working principle and evaluation parameters were summarized briefly. The preparation methods and electrochemical properties of different carbonaceous materials were compared and classified. It was found that the surface situation (e.g., porous structure, hydrophilic) of carbonaceous materials strongly affect the electrochemical performances of supercapacitor. So far, active carbons would be the most applicable carbonaceous electrode materials owing to their good chemical stability and conductivity, extensive accessibility inexpensiveness. But their energy densities still fall behind practical demands. Both theoretical calculations and experimental studies show that surface modification and doping of carbonaceous materials can not only optimize their pore size, structure, conductivity and surface properties, but also can introduce extra pseudocapacitance into these materials. Considering global environmental pollution and energy shortage problems nowadays, we sincerely suggested that future work should focus on domestic, medical and industrial wastes residues derived carbonaceous materials and scaled production process such as reactors and exhaust gas treatment.

This paper investigates the effect of the electric double layer capacitor (EDLC) in reducing stress and prolonging the battery lifespan in a hybrid energy storage system (HESS). A 65 F, 16.2 V EDLC supercapacitor was connected in a laboratory experiment to produce its charge/discharge profile at a constant current of 5 and 10 A. The EDLC's Faranda or "two branch model" mathematical parameters were extracted from the experimental charge/discharge profile. The extracted parameters were used as inputs to design the Python/MATLAB/Simulink (PMS)-hybrid model of the EDLC. The charge/discharge profiles of the simulated PMS model of the EDLC were then compared to the charge/discharge profiles derived from the experimental setup of the EDLC and were found to match. The PMS model of the EDLC was then used as a subcomponent in an HESS system modelled in MATLAB/Simulink. Using constant load conditions, the battery's voltage, current, power and state of charge (SOC) were analyzed for a battery energy storage system (BESS) without a supercapacitor and then compared to an HESS system with a supercapacitor in an experimental setup. This process was repeated with the simulated PMS model of the EDLC in MATLAB/Simulink for HESS and without the EDLC for BESS. Finally using a variable load in an experimental setup, the battery's voltage and current were analyzed for a BESS system and compared to an HESS system. All these data show that, in an HESS system with a supercapacitor, there is less stress on the battery with a load applied. This is indicated by the voltage and current values in an HESS system being consistently more stable with respect to time as compared to the BESS system. As a result, in an HESS system, the battery will have a longer lifespan. [ABSTRACT FROM AUTHOR]

In this paper, a facile and rapid aqueous-based electrochemical technique was used for the phase conversion of Ni into Ni(OH)2 thin film. The Ni(OH)2 thin film was directly converted and coated onto the network surface of Ni foam (NF) via the self-hydroxylation process under alkaline conditions using a simple cyclic voltammetry (CV) strategy. The as-formed and coated Ni(OH)2 thin film on the NF was used as the catalyst layer for the direct growth of carbon nanotubes (CNTs). The self-converted Ni(OH)2 thin film is a good catalytic layer for the growth of CNTs due to the fact that the OH− of the Ni(OH)2 can be reduced to H2O to promote the growth of CNTs during the CVD process, and therefore enabling the dense and uniform CNTs growth on the NF substrate. This binder-free CNTs/NF electrode displayed outstanding behavior as an electric double-layer capacitor (EDLC) due to the large surface area of the CNTs, showing excellent specific capacitance values of 737.4 mF cm−2 in the three-electrode configuration and 319.1 mF cm−2 in the two-electrode configuration, at the current density of 1 mA cm−2 in a 6 M KOH electrolyte. The CNTs/NF electrode also displayed good cycling stability, with a capacitance retention of 96.41% after 10,000 cycles, and this the excellent cycling performance can be attributed to the stable structure of the direct growth of CNTs with a strong attachment to the NF current collector, ensuring a good mechanical and electrical connection between the NF collector and the CNTs. [ABSTRACT FROM AUTHOR]