Supercapacitor Device Research Articles

Fabrication of nickel cobalt based-phosphides prepared from VIB group elements (M = Cr, Mo, W)-doped NiCo-LDH precursors for supercapacitors: Effects of VIB group elements (M = Cr, Mo, W) on capacitance of nickel cobalt based-phosphides

Metal-doped nickel cobalt based-phosphides are an effective method to improve electrochemical performance. This work aims to prepare nickel cobalt based-phosphides based on VIB group elements (M = Cr, Mo, W)-doped nickel cobalt hydroxides precursors. The influences of different mass of metal salts loading into phosphides on the electrochemical performance are investigated. The results show the flower shape morphology for all samples. Further, the excellent specific capacitances are to be 1839, 1599 and 1786 F g−1 for NiCoCr phosphides (NCCP), NiCoMo phosphides (NCMP) and NiCoW phosphides (NCWP), respectively, higher than pristine NiCo phosphides (NCP, 1128 F g−1) at 1 A g−1. In addition, the assembled supercapacitor device can reach maximum energy density of 29 Wh kg−1 with excellent capacitance retention.

Unravelling the electrochemistry of Ni-MOF derived nickel phosphide/carbon composite electrode and redox additive electrolyte for high performance supercapacitors

The performance and operation of an energy storage device are significantly influenced by the electrolyte and electrode materials. Therefore, it is crucial to develop an electrode material with a rational design and achieve compatibility with the electrolyte. In this study, we prepare Ni-MOF derived nickel phosphides/carbon (NP@C) nanostructure as an electrode for supercapacitor application. The as synthesized material provides more redox-active sites, better spatial utilization, improved conductivity, and a high-polarized surface that will speed up ion migration at electrode/electrolyte. Also, the usage of redox additive electrolyte (0.2 M K3[Fe (CN)6] in 1 M Na2SO4) further complements the redox active sites and hence the improved charge transport. Therefore, NP@C electrode achieved a remarkable 2136.3 F/g of capacitance at 3 A/g with 90.6 % of capacitance retention after 5000 charge-discharge cycles. In addition, the surface-diffusion studies confirms that NP@C shows high diffusion contribution of 82.6 % in redox electrolyte than that of 25.1 % in 1 M Na2SO4. Furthermore, NP@C//NP@C symmetric supercapacitor device in redox additive electrolyte also delivered remarkable performance rendering high energy density of 52.5 Wh/kg at a power density of 750 W/kg. In addition, NP@C//NP@C also shows the long-term stability with attenuating only 7.2 % of initial capacitance value after 10000 charge-discharge cycles. In addition to this, the device performs extremely well when tested for self-discharge studies. Hence, this study demonstrates the perfect harmony of NP@C electrodes and redox additive electrolyte to fabricate a high-performance supercapacitor.

Chemical vapor deposition-based synthesis of cost-effective binder-free nanostructured Ag/MoS2/Ni–F electrode material for portable energy storage devices

The synthesis of novel electrode materials (E-Ms) is the demand of scientific community to overcome the energy crisis in developing countries. Hereon, the molybdenum disulfide (MoS2) and silver-wrapped MoS2 (Ag/MoS2) E-Ms are synthesized on hierarchical-nickel foam (Ni–F) via a cost-effective chemical vapor deposition technique. The synthesized E-Ms are characterized in terms of structure, chemical bonding, surface morphology, weight percentage of elements, porosity and energy storage capability. The X-ray diffraction analysis is indicated that by wrapping of Ag species, the diffraction peaks associated with MoS2 material not only moved to higher Bragg's angles but their peaks intensities are also lowered which showed the existence of structural defects in the synthesized E-Ms. The surface area of cauliflower like Ag/MoS2/Ni–F E-Ms (170 m2g-1) is higher than the surface area (60 m2g-1) of MoS2/Ni–F E-Ms. The cauliflowers based Ag/MoS2/Ni–F E-Ms is presented supreme specific capacitance of 4200 Fg-1 as compared to MoS2/Ni–F E-Ms (2518 Fg-1) at 1Ag-1. The implementation of power law and Dunn's model is demonstrated that the synthesized E-Ms can behave like a battery and supercapacitor (0.67 < b < 0.92) nature. The diffusive-controlled contribution for cauliflower-based synthesized E-Ms is 97 % at 5 mVs−1 and became 88 % at 70 mVs−1. The assembled asymmetric supercapacitor (ASC) device is exhibited the specific capacitance of 957 Fg-1, energy density of 366–284 Whkg−1 and power density of 1494–14110 Wkg-1. The ASC device could sustain the capacitance retention of 94 %, Coulombic efficiency of 99 % even for 20000 cycles in contrast to capacitance retention of 95 % and Coulombic efficiency of 97.89 % of the synthesized E-Ms.

All-in-one flexible paper-based self-powered energy and display system employing complementary properties of printed PEDOT:PSS/PANI:PSS dual-electrode with a dual-sided triboelectric nanogenerator

A Self-powered energy and display system (SPEDS) has been developed by integrating functionalities of energy harvesting, storage, and multicolor display, heralding innovative solutions for integrated electronic devices. An all-in-one multi-information SPEDS is proposed through incorporating a multicolor electrochromic supercapacitor device (ESCD) with a dual-sided triboelectric nanogenerator (TENG), all screen-printed on a paper substrate. The synergistic enhancement in the conductive, capacitive, and electrochromic performance is realized by exploiting the complementary properties of PEDOT:PSS/PANI:PSS to form a simplified structure of ESCD, in which the electrode and electrochromic layers are integrated into one shared layer, resulting in a wide color gamut and an enhanced capacitive performance of 3.4 mF/cm². Electrochromic electrodes having identical composition exhibit independent color changes at the anode and cathode, thereby featuring a combined color display indicating multi energy-related information. Moreover, the conductive layer fabricated through patterned printing on the paper substrate, serves as both the electrode layer for TENG and the interconnect circuitry with the prepared ESCD. Furthermore, a double-sided TENG was realized by exploiting the triboelectric properties of the paper substrate and then a self-powered energy display wristband was constructed, exemplifying a novelty application utilizing the multi-information indicator properties for energy display derived from the dual-sided friction power generation.

Review of Battery-type Transition Metal (Cu, Co, and Ni) Oxide Based Electrodes: From Fundamental Science to Fabrication of a Hybrid Supercapacitor Device

Review of Battery-type Transition Metal (Cu, Co, and Ni) Oxide Based Electrodes: From Fundamental Science to Fabrication of a Hybrid Supercapacitor Device

Electrochemical performance of Fe-doped SnSe material electrodes for supercapacitors

This paper synthesized Fe-doped SnSe nanoparticles (NPs) through the co-precipitation technique. The X-ray diffraction (XRD) confirms the orthorhombic crystal structure of Fe-doped SnSe NPs. The chemical states of Sn, Fe and Se elements were identified by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDAX). The galvanostatic charge-discharge (GCD) was used to measure the power efficiency of Fe-doped SnSe electrodes. The specific capacitance of 1283 F/g at a current density of 5 A/g was obtained using a three-electrode system. Further, the Fe-doped SnSe electrode shows a specific energy (Es) of 64 Whkg−1 at a specific power (Ps) of 1500 Wkg−1, respectively. The Fe-doped SnSe electrode exhibits a capacitance retention of 101 % for 1000 GCD cycles in a two-electrode system. This study confirms that the Fe-doped SnSe electrodes are the substitute and life-lasting electrodes for supercapacitor devices.

Compositionally Tunable Mn-V-Fe Phosphoselenide Nanorods with Minimal Ion-Diffusion Barrier as High Energy Density Battery Electrode Materials.

The design and synthesis of novel heterostructured electrode materials are crucial to enable the fabrication of efficient supercapacitor devices. In this regard, transition metal phosphochalcogenides (S, Se) are promising candidates owing to their exotic electronic properties. Herein, a facile two-step hydrothermal protocol was used to synthesize binary and ternary metal phospho-selenide electrodes (Mn-Fe-P-Se, V-Fe-P-Se, Mn-V-P-Se, and Mn-Fe-V-P-Se). The chemical composition, morphology, and structure of the as-fabricated materials were fully investigated. The three-electrode electrochemical evaluation at 1.0 A g-1 demonstrated that the ternary metal electrode (MFVP-Se) exhibits a high capacity of 1968.63 C g-1. To assess the practical value of the rationally designed Mn-Fe-V-P-Se electrode material, Mn-Fe-V-P-Se was used as a positive electrode coupled with activated carbon (AC) as a negative electrode to assemble a hybrid supercapacitor device. This Mn-Fe-V-P-Se//AC device delivers a power density of 1999.96 W kg-1 with a high energy density of 149.88 Wh kg-1 coupled with no capacity loss after 5000 charging/discharging cycles. Additionally, density functional theory calculations revealed that our electrode exhibits suitable adsorption energy for OH- ions with a minimal diffusion barrier for ions.

Friendly Environmental Strategies to Recycle Zinc-Carbon Batteries for Excellent Gel Polymer Electrolyte (PVA-ZnSO4-H2SO4) and Carbon Materials for Symmetrical Solid-State Supercapacitors.

In this report, we introduce a novel idea to prepare a redox additive in a gel polymer electrolyte system of PVA-ZnSO4-H2SO4 based on zinc-carbon battery recycling. Here, zinc cans from spent zinc-carbon batteries are dissolved completely in 1 M H2SO4 to obtain a redox additive in an aqueous electrolyte of ZnSO4-H2SO4. Moreover, carbon nanoparticles and graphene nanosheets were synthesized from carbon rod and carbon powder from spent zinc-carbon batteries by only one step of washing and electrochemical exfoliation, respectively, which have good electrochemical capability. The three-electrode system using a ZnSO4-H2SO4 electrolyte with carbon nanoparticles and graphene nanosheets as working electrodes shows high electrochemical adaptability, which points out its promising application in supercapacitor devices. Thus, the symmetrical solid-state supercapacitor devices based on the sandwich structure of graphene nanosheets/PVA-ZnSO4-H2SO4/graphene nanosheets illustrated the highest energy density of 39.17 W h kg-1 at a power density of 1700 W kg-1. While symmetrical devices based on carbon nanoparticles/PVA-ZnSO4-H2SO4/carbon nanoparticles exhibited a maximum energy density of 35.65 W h kg-1 at a power density of 1700 W kg-1. Moreover, these devices illustrate strong durability after 5000 cycles, with approximately 90.2% and 73.1% remaining, respectively. These results provide a promising strategy for almost completely recycling zinc-carbon batteries, one of the most popular dry batteries.

Optimizing phosphorene nanosheets for high performance all-solid asymmetric supercapacitors: A theoretical and experimental insight

This study probably for the first-time introduced a phase and morphology-tuned scalable, cost-effective method for large-scale production of Black Phosphorous/Phosphorene (BP), and investigated their in-depth electrochemical properties. Utilizing a one-pot mild wet chemical-assisted hydrothermal route in ethylenediamine, high-quality BP nanosheets were synthesized from amorphous red phosphorus (RP) with nearly 100 % conversion efficiency, yielding 7.1352 g for one batch at 130–170 °C. The resulting phosphorene nanosheets exhibited a small crystalline size (2.708 nm), hierarchically porous morphology, a 1.64 eV direct optical bandgap aligned with theoretically calculated bandgap using LDA approximation, and various structural defects, along with large specific surface area (50 m2g−1) and reduced number of layers (4–5) compared to prior literatures, suggesting electrochemical superiority. CV and GCD measurements in the potential window of −0.7 V to 0.1 V revealed its highest pseudo-capacitance response (84.91 %), reaching a maximum specific capacitance value of 759.748 Fg−1 at current density 2 Ag−1, surpassing all previous records. Moreover, BP displayed excellent cyclic stability of 89.8 % after 10,000 cycles, making it an excellent electrode material for supercapacitors. A solid-state asymmetric supercapacitor device (HASD), using BP, successfully lighted up 6 red LEDs for 10 s, achieving maximum specific energy density at 73.43 Wkg−1 at a power density of 1500 Wkg−1.

Phenolic resin filled wood-derived hierarchically porous carbon monolith for high areal capacitance supercapacitors

Wood-based electrodes are widely used in supercapacitors due to their renewable and three-dimensional self-supported properties. Low space utilization of wood-based electrodes seriously restricts its practical applications. In this paper, a wood/phenolic resin composite was designed, which can effectively enhance the space utilization of wood and ensure a hierarchical porous structure. The prepared balsa wood/phenolic resin composite-derived electrode obtained a high areal capacitance (8169 mF cm–2), which is 954 % of pure balsa wood-based electrode. Moreover, the assembled symmetrical supercapacitor device exhibits outstanding electrochemical performance, displaying a high areal capacitance of 3.3 F cm–2, and a competitive volumetric energy density of 2.88 mWh cm–3. More importantly, this design has been successfully used to prepare various species wood-derived electrodes. Therefore, as a general strategy, which gives a novel idea for the design of wood-derived electrodes and may affect other fields using wood-based materials.

High-performance pristine ZIF-67 asymmetric supercapacitor device with excellent energy and power density for energy storage application

The current work describes a simple and safe method for creating ZIF-67 (zeolitic imidazolate framework-67) nanostructures. X-ray diffraction (XRD) patterns reveal that the material exhibits a cubic phase free from contaminating impact. The synthesized material has a notable porosity, a high specific surface area (SSA) of ∼ 1071 m2 g−1, and a clearly defined hexagonal shape with high-resolution transmission electron microscope (HRTEM) analysis. Moreover, the electrochemical analysis in the three-electrode setup shows an extraordinary specific capacitance (CS) of 472 F g−1 and exceptional cyclic performance of 91.6 % retention in a 6 M NaOH aqueous electrolyte. Furthermore, activated carbon (AC) is being used as the negative electrode and ZIF-67 as the positive electrode to design a device with a wide potential window (1.50 V). The outstanding performance of the Asymmetric supercapacitor (ASC) device is evident in its exceptional CS (358 F g−1). This, coupled with its remarkable energy (22 Wh kg−1) and power density (4164 W kg−1), highlights its suitability for demanding energy storage applications. Notably, the device demonstrates extraordinary cyclic stability, retaining over 132 % of its initial capacitance after 5000 charge-discharge cycles, solidifying its long-term reliability. Finally, LEDs (Light Emitting Diodes) of various colors are being illuminated using three series-connected devices. Hence, the recent work is illustrating the possible practical benefit of the ongoing development of supercapacitive energy storage systems.

In-depth analysis of VARTM-based solid-state supercapacitors utilizing CNT-dispersed cobalt-bismuth-samarium ternary hydroxide on woven carbon fiber for enhanced energy storage

Multi-metal hydroxides possess unique physical and chemical properties, making them promising candidates for supercapacitor working electrodes. Enhancing their electrochemical performance can be achieved through a combination with carbon materials. In this study, we synthesized a composite material by hydrothermally dispersed 4, 6, and 10 wt% carbon nanotubes (CNT) into ternary cobalt-bismuth-samarium hydroxide (CoBiSm-TOH). These nanocomposites were employed as the material for the working electrode in a supercapacitor. The findings reveal that at 1.5 A/g, the specific capacitance of CNT3@CoBiSm-TOH, using a three-electrode system, was found to be 852.91 F/g, higher than that of CoBi-BOH, CoBiSm-TOH, CNT1@CoBiSm-TOH and CNT5@CoBiSm-TOH—measuring 699.69, 750.34, 789.54 and 817.79 F/g, respectively. Moreover, CNT3@CoBiSm-TOH electrodes exhibited a capacitance retention of around 88% over 10,000 cycles. To demonstrate practical applicability, CNT3@CoBiSm-TOH was grown on woven carbon fiber (WCF), and a solid-state supercapacitor device was developed using the VARTM (vacuum-assisted resin transfer molding). This device displayed a specific capacitance of 272.67 F/g at 2.25 A/g. Notably, it achieved a maximum energy density of 53.01 Wh/kg at a power density of 750 W/kg and sustained excellent cycle stability over 50,000 cycles, maintaining 70% of its initial capacitance. These results underscore the importance of interfacial nanoengineering and provide crucial insights for the development of future energy storage devices.

Comparative study of the reduction techniques of Graphene Oxide for Zinc Ion hybrid Storage Application

The increasing demand for low cost and high energy storage devices has given rise to the hybrid supercapacitor device. To overcome the safety issues of the Lithium and Sodium-based devices Zinc ion hybrid supercapacitors (ZIHSCs) are a promising alternative. These devices amalgamate the energy density and power density requirements which makes them suitable for varied applications. The device construction comprises of a zinc anode, zinc-based electrolyte and capacitive type cathode material. Carbon based nanomaterials such as reduced graphene oxide (RGO) are predominantly used as potential cathodes. The strategies involved in obtaining RGO changes the structural characteristic of the samples. This study compares three different strategies such as Chemical reduction (c-RGO), Microwave reduction (m-RGO) and Solar reduction (s-RGO). It was observed that the employment of each these techniques render the change in the physical properties of the materials like number of defect, change in the surface are, porosity and in-situed developed functional group, especially oxygen species. These changes were analyzed thoroughly by various techniques like Raman, Fourier, X-ray diffraction and X-Ray photoelectron spectroscopy. The overall study reveals that solar reduction route shows enhanced surface area and porosity and decrease in defect concentration. Further due to this enhanced property in s-RGO the zinc ion storage capacitance of the fabricated ZIHSC was 200 F/g with a high cyclic stability of 5100 cycles at a current density of 10 A/g. The enhanced energy density thus obtained was 111 Wh/kg corresponding to a power density of 10 KW/kg.

Iron Sulfide Microspheres Supported on Cellulose-Carbon Nanotube Conductive Flexible Film as an Electrode Material for Aqueous-Based Symmetric Supercapacitors with High Voltage.

Nanostructured iron disulfide (FeS2) was uniformly deposited on regenerated cellulose (RC) and oxidized carbon nanotube (CNT)-based composite films using a simple chemical bath deposition method to form RC/CNT/FeS2 composite films. The RC/CNT composite film served as an ideal substrate for the homogeneous deposition of FeS2 microspheres due to its unique porous architecture, large specific surface area, and high conductivity. Polypyrrole (PPy), a conductive polymer, was coated on the RC/CNT/FeS2 composite to improve its conductivity and cycling stability. Due to the synergistic effect of FeS2 with high redox activity and PPy with high stability and conductivity, the RC/CNT/FeS2/PPy composite electrode exhibited excellent electrochemical performance. The RC/CNT/0.3FeS2/PPy-60 composite electrode tested with Na2SO4 aqueous electrolyte could achieve an excellent areal capacitance of 6543.8 mF cm-2 at a current density of 1 mA cm-2. The electrode retained 91.1% of its original capacitance after 10,000 charge/discharge cycles. Scanning electron microscopy (SEM) images showed that the ion transfer channels with a pore diameter of 5-30 μm were formed in the RC/CNT/0.3FeS2/PPy-60 film after a 10,000 cycle test. A symmetrical supercapacitor device composed of two identical pieces of RC/CNT/0.3FeS2/PPy-60 composite electrodes provided a high areal capacitance of 1280 mF cm-2, a maximum energy density of 329 μWh cm-2, a maximum power density of 24.9 mW cm-2, and 86.2% of capacitance retention after 10,000 cycles at 40 mA cm-2 when tested at a wide voltage window of 1.4 V. These results demonstrate the greatest potential of RC/CNT/FeS2/PPy composite electrodes for the fabrication of high-performance symmetric supercapacitors with high operating voltages.

Preparation and capacitance performance of NiCo layered double hydroxide by multi-step constant current electrodeposition method

In comparison with single-step electrodeposition, multi-step electrodeposition for electrode preparation is more effective in releasing internal stresses, utilizing the highly efficient deposition time at the beginning of the electrodeposition, improving deposition efficiency, and producing adhesive-free high-performance electrodes with controllable mass. In this paper, NiCo layered double hydroxide (NiCo-LDH) with similar mass was successfully deposited by a two-electrode constant-current electrodeposition method using nickel foam as the substrate through different electrodeposition steps. A comparative study was conducted on the effects of NiCo-LDH deposition steps on the morphology, total deposition time, and electrochemical performance of NiCo-LDH samples. The results show that the mass of NiCo-LDH grown on foam nickel is similar when the number of deposition steps is from 1 to 6 at 12–13 mg, the coating of foam nickel substrate became more uniform. The total deposition time has decreased from 2550 s for 1-step deposition to 1542 s for 6-step deposition, reducing the occupation time of the electrodeposition equipment. As the number of deposition layers increases, the specific capacitance of NiCo-LDH shows a trend of first increasing and then stabilizing. The high mass specific capacitance of NiCo-LDH electrode material deposited in 6 steps is 953 F g−1 at a current density of 3 mA cm−2. The assembled asymmetric supercapacitor device achieved an energy density of 0.309 mWh cm−2 at a power density of 4.25 mW cm−2, and a capacitance retention rate of 94% after 10,000 cycles at a current density of 40 mA cm−2. This indicates that the NiCo-LDH material prepared by multi-step electrodeposition method has good capacitance performance, providing a simple and time-saving method for manufacturing large-scale multi-step electrodeposition of adhesive-free supercapacitor electrodes.

Towards Using Polybenzidine-Graphene Oxide Sheet on Graphite as a New System for Supercapacitor Device Fabrication

Polybenzidine-anodic exfoliated graphene oxide sheet (PB/AEGO Nsh) graphite sheet electrode was easily fabricated via electrochemical anodization of the graphite sheet followed by in situ chemical polymerization of benzidine on the anodized graphite sheet. Fourier transform infrared spectroscopy, dispersive Raman spectroscopy, and scanning electron microscopy investigations confirm that benzidine is successfully polymerized on the graphene oxide sheets created by the anodizing process. Evaluating the electrochemical performance of PB/AEGO Nsh graphite sheet electrode shows that the electrode has an excellent specific capacitance of about 841.89 mF cm−2 at 1 mA cm−2 in aqueous 1.0 M H2SO4 electrolyte. To check the applicability of the constructed electrode, a solid-state symmetric supercapacitor device separated by PVA/H2SO4 gel electrolyte was fabricated and its electrochemical performance was checked. Investigation of the capacitance behavior of the fabricated supercapacitor device indicates that the device has an excellent specific capacitance of about 334.7 mF cm−2 (230.11 F g−1) at 1 mA cm−2, maximum specific energy, and power density of 225 mWh cm−2 and 5000 mW cm−2, and cyclic life of 76.7% after 10000 galvanostatic charge/discharge cycles with non-IR drop. PB/AEGO Nsh graphite sheet electrode shows great potential for use in energy storage devices.

Eco-friendly preparation of nitrogen-doped porous carbon materials for enhanced solid-state supercapacitor device

In the last years, researchers all over the world have been looking for biomass-derived porous carbon materials, due to the possibilities for large-scale synthesis, easy to control the pore structure, and high specific surface area. Activated heteroatom doped porous carbon (AHPC) with a high porosity was made by treating inexpensive waste Ficus elastica leaves with a base. The electrochemical performance of the produced activated carbon has been evaluated in various electrolytes, including basic, neutral, and acidic electrolytes. At a current density of 1 A/g in the acidic electrolyte, the specific capacitance of the activated carbon AHPC electrode is higher, 456 F/g, compared to other electrolytes. The symmetric supercapacitor device is built using PVA-H2SO4 gel electrolyte, and its electrochemical performance is evaluated. In addition, the energy density of the built symmetric supercapacitor device is higher than the existing commercial supercapacitors, achieving 62 Wh/kg at a power density of 15.2 kW/kg. This is because the porous carbon has a hierarchical pore distribution and a heteroatom-enriched structure, which allows for rapid charge/mass diffusion channels, and a vast ion-accessible network.

Efficient Electrochemical Performance of Sr(OH)2:MnO2 Binary Composites for Solid State Symmetric Supercapacitor

AbstractIn this study, we synthesized a binder‐free composite electrode based on Sr(OH)2/MnO2 material. The active electrode was prepared using the layer‐by‐layer (LBL) technique. The surface architecture of the sample was examined through scanning electron microscopy (SEM) and high‐resolution scanning electron microscopy (FE‐SEM). Further, the microstructural information of the electrode was revealed via transmission electron microscopy (TEM). The composite confirmation was ensured through X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and energy‐dispersive X‐ray spectroscopy (EDX) spectra with mapping analysis. The electrode exhibited the maximum specific capacitance of 554.7 F g−1 at 5 mVs−1 in the 6 M KOH electrolyte. The electrode maintained ~65 % capacitance retention after 10,000 galvanostatic charge‐discharge (GCD) cycles. Furthermore, the assembled symmetric supercapacitor device exhibited the highest specific capacitance value of 124.7 F g−1 @ 5 mVs−1 within a potential span of 1.2 V. This device demonstrated the capability to illuminate light‐emitting diodes (LEDs) of different colors. The energy and power densities of the device were calculated as 26.66 Wh kg−1 and 9884.54 W kg−1 respectively. The stability performance of the device was ~57 % after 10,000 GCD cycles. These findings strongly suggest that the material and the device represent promising options for future energy storage applications.

Review on Biomass Derived Activated Carbons as Electrochemical Electrode Material for Supercapacitor Device

Abstract: To face the challenge of the finite nature of fossil fuels and large energy crises across the globe, there is an urgent requirement for sustainable and renewable energy sources. Moreover, it is essential to focus on energy storage in order to meet the demand of future generations. Among various energy storage devices such as fuel cells, batteries, capacitors, supercapacitors, flywheels, etc., it is the supercapacitor device that has elicited extensive research interest recently because of prominent features like high power density, fast recharge capability, and long cycle life. The main objective of this article is to review the enhancement of the electrochemical performance of supercapacitor devices. The electrochemical properties of the supercapacitor device majorly depend on the electrode materials used, which include carbonaceous materials, metal oxides, and conducting polymers. In order to reduce energy shortages and environmental pressure, carbon materials derived from biomass/waste materials have been considered remarkable candidates for electrode materials with the advantages of high abundance, low cost, and environmental friendliness. This review shows the complied study of various methodologies for the preparation of activated carbons derived from different biomass residues such as plants, animals, and microorganisms, which have been investigated in the past few years as electrochemical electrode materials for supercapacitors. Further, ongoing challenges and potential improvements in this area for creating efficient energy storage devices are also discussed. The goal of this review article is to aid in the creation of new insights for energy storage applications of biomass-generated carbons that will lead to sustainable energy development.

Enhancing capacitance performance of functional group assisted carbon quantum dots derived from turmeric plant waste

Supercapacitors have attracted significant attention in modern devices as a promising solution for electrical energy storage due to their remarkable capability to undergo rapid charge and discharge cycles. While various materials are employed in the construction of supercapacitors, carbon-based materials emerge as a predominant choice within the commercial realm. In present report, our intention is to develop an effective supercapacitor device derived from natural biomass. Therefore, we have synthesized water soluble, monodisperse and fluorescent carbon quantum dots (CQDs) from turmeric leaves (Curcuma caesia) via a single step hydrothermal carbonization. Further, the doctor blade technique was employed to coat a layer of CQDs on stainless steel substrate using PVA as a binder. We observed the functional groups associated with QDs triggers the fast diffusion of ions and transmission of electrons with conducting substrate and electrolyte and thereby effectively charge and discharge mechanism. The supercapacitor based on carbon quantum dots (CQDs) based electrode exhibits exceptional performance characteristics with a remarkable specific capacitance of 468 F/g and highest energy density of 78.6 Wh/kg, superior to the values reported for most carbon-based supercapacitors. Further, we demonstrated the light dependent capacitive enhancement by depositing a thin P3HT layer over CQDs. Moreover, CQDs-based supercapacitor achieves a maximum power density of 733.2 W/kg when operated in a 1 M KOH electrolyte solution and an excellent capacitive retention of about 80 % even after 5000 cycles.