Energy Density Of Supercapacitors Research Articles

Mixed Phase Nickel‐Cobaltite for High Energy Density Asymmetric Supercapacitor using Cathodic Overpotential Synthesis Route

AbstractFor flexible solid‐state electronics, it is essential to accelerate the transition to renewable materials and environmentally friendly manufacturing procedures. Symmetric supercapacitors (SCs) have a limited voltage window and capacity, hampering their use in practical applications such as portable electronics, hybrid vehicles, and transportation. To improve the energy density of supercapacitors, the strategy of using an advanced pseudo‐capacitive electrode in an asymmetric device configuration is feasible and effective. Here, we report on the design and synthesis of hierarchical honeycomb‐like morphology with controlled Ni/Co molar ratios of NiCo2O4 (NCO) coatings on flexible stainless‐steel substrates utilizing high cathodic overpotential deposition. The NCO electrode retains 90.5% of the three‐electrode capacitance (911 F g−1, or 594 C g−1) even after increasing the current density to 10 A g−1 (∼10 times). Furthermore, we have fabricated a 1.5 V asymmetric supercapacitor (ASC, NCO//AC); such a device delivers maximum specific energy and specific power of 76.8 Wh kg−1 and 16858 W kg−1 in 2 M KOH electrolyte and excellent cycling stability (∼88% retention after 5000 cycles).

One pot synthesis of carbon decorated NiO nanorods as cathode materials for high-performance asymmetric supercapacitors

The composites of metal oxides and carbons are of research interest for improving the energy density of supercapacitors. In this work, we have demonstrated a simple one-pot hydrothermal synthesis method to prepare NiO nanorods followed by carbon framework decorated NiO nanorods (NiO@C). The NiO@C electrode showed an excellent specific capacitance of 1360 F g−1 compared to pristine NiO of 890 F g−1 at 1 A g−1 in a voltage range of 0.05 to 0.5 V in 1 M KOH electrolyte. The NiO@C electrodes showed excellent cycle stability over 10,000 cycles with 90 % capacitance retention. Asymmetric supercapacitors fabricated using corncob-derived activated carbon anode, and NiO@C cathode delivers a power density of 4574 W kg−1 at an energy density of 21.6 Wh kg−1. The enhanced capacitance of NiO@C material is due to the synergistic effect of the pseudocapacitive of NiO nanorods and the electric double-layer capacitance of the carbon matrix. Besides, the carbon framework facilitates quick charge acceptance, improved cycling stability, and rate capability. The cost-effective one-pot synthesis and eco-friendly NiO nanorods with easy electrode fabrication open opportunities for developing high-energy-density NiO-based supercapacitors.

Flexible double-wall carbon foam/Cu-Co oxides based symmetric supercapacitor with ultrahigh energy density

Electrochemical supercapacitors are regarded as a promising electrochemical energy storage device, because of its fast chargeability, long cycle life, and high power density. The connection of porous carbon and extensive electroactive substances have significantly improved their performance. However, the unsuitable constructing strategy and unclear electrochemical mechanism lead to a mismatch between the fast double-layer effect and the sluggish Faradaic behavior at the electrode, degrading the energy density and capacitance performances. Herein, the construction strategy based on the double-wall carbon foam, carbon nanotubes and copper nanocubes provides enhanced electronic structure and ion transport path, resulting in accelerated proton transport and redox insertion/deinsertion processes, as well as surprising electrochemical behaviors of Cu-Co oxide on both positive and negative electrodes (927.9 and 427.0 F g−1 at 1 A g−1). A flexible symmetric supercapacitor assembled with the SCF/CNT@Cu/Cu-Co-O delivers a extremely excellent performance. At 1 A g−1, the specific capacitance is 337.8 F g−1, the energy density hits 60 Wh kg−1 at the power density of 17.8 kW kg−1. At 10 A g−1, the energy density is up to 120.1 Wh kg−1, representing the top energy density of supercapacitors. Combining systematical structural optimization and mechanism study, this work broadens the fabricating strategy of hierarchical nanostructures and high-performance electrode materials for energy storage.

Recent research progress of conductive polymer-based supercapacitor electrode materials

With the serious impact of fossil fuels on the environment and the rapid development of the global economy, the development of clean and usable energy storage devices has become one of the most important themes of sustainable development in the world today. Supercapacitors, known as ultracapacitors, have been supposed to be one of the most promising candidates to meet the requirements of human sustainable development, due to their advantages such as high capacity, high power density, high charging/discharging speed, long cycle life, and low processing cost. However, the low energy density of supercapacitors limits their large-scale application. Therefore, it is of great significance to develop high energy density supercapacitors and use them as power sources for practical devices. Conductive polymer-based electrode materials have unique advantages such as high theoretical capacitance, good conductivity, and good flexibility, and have high potential in supercapacitors. The research on conductive polymer-based electrode materials has promoted the rapid development of the field of supercapacitors. This review summarizes recent research progress on conductive polymers (including polypyrrole, polyaniline, and polythiophene), conductive polymer-based binary composites, and conductive polymer-based ternary and quaternary composites for supercapacitor electrodes. Furthermore, a summary of the use of conductive polymer-based textiles and fibers for flexible supercapacitors is also presented, along with the current challenges and future perspectives for conductive polymer-based supercapacitors.

Recent Progress of 2D Layered Materials in Water-in-Salt/Deep Eutectic Solvent-Based Liquid Electrolytes for Supercapacitors.

Supercapacitors are candidates with the greatest potential for use in sustainable energy resources. Extensive research is being carried out to improve the performances of state-of-art supercapacitors to meet our increased energy demands because of huge technological innovations in various fields. The development of high-performing materials for supercapacitor components such as electrodes, electrolytes, current collectors, and separators is inevitable. To boost research in materials design and production toward supercapacitors, the up-to-date collection of recent advancements is necessary for the benefit of active researchers. This review summarizes the most recent developments of water-in-salt (WIS) and deep eutectic solvents (DES), which are considered significant electrolyte systems to advance the energy density of supercapacitors, with a focus on two-dimensional layered nanomaterials. It provides a comprehensive survey of 2D materials (graphene, MXenes, and transition-metal oxides/dichalcogenides/sulfides) employed in supercapacitors using WIS/DES electrolytes. The synthesis and characterization of various 2D materials along with their electrochemical performances in WIS and DES electrolyte systems are described. In addition, the challenges and opportunities for the next-generation supercapacitor devices are summarily discussed.

Boosting the capacitance of MOF-derived carbon-based supercapacitors by redox-active bromide ions

Supercapacitors have attracted tremendous attention due to their merits of excellent cycling stability, remarkable power density and low cost. Nevertheless, the low energy density of supercapacitors has encumbered their further development for practical applications. Development of advanced high-energy supercapacitors is considered to be of crucial importance. In this work, the capacitance of MOF-derived carbon-based supercapacitor is dramatically improved by addition of soluble redox-active LiBr electrolyte additive. The post analysis of this redox-active electrolytes reveal that the Br−/Br2 couple are the main pseudocapacitance contribution in the early cycles stages (<140 cycles), which gradually reaches an equilibrium state and converts into Br–/Br3– redox couples after 160 cycles. The achieved specific capacitance of the assembled supercapacitors is up to 825.6 F g−1 in the added-bromide-ion (ABI) electrolyte. The performance is over seven-fold as high as bromide-free (BF) electrolyte at current density of 1 A g−1.

Structurally stable Fe–Ni–Co phosphide/graphene and nitrogen-doped carbon/graphene constructed by atomic layer deposition for high-performance hybrid supercapacitor

Constructing high-volume hybrid supercapacitors (HSCs) based on transition metal phosphides (TMPs) cathode and porous carbon anode is an effective way to promote energy density of supercapacitors (SCs). Herein, FeNiCoP nanoneedles are uniformly and stably coated on reduced graphene oxide (FeNiCoP/rGO) by atomic layer deposition technology. The synergistic effect between the large surface area of rGO and high specific capacity of TMP improves electrode reaction kinetics by fully exposing the active sites of FeNiCoP/rGO and shortening the ion/electron transport path. Therefore, FeNiCoP/rGO reveals a high specific capacitance (184.8 mAh/g at 1 A/g), favorable rate performance (151.1 mAh/g at 10 A/g) and excellent structural stability. To better exploit the advantages of the performance of the FeNiCoP/rGO, an anode of porous nitrogen-doped carbon/rGO (N–C/rGO) was prepared. Benefitting from the rich void structure and the nitrogen doping, N–C/rGO delivers a specific capacitance of 240 F/g at 1 A/g. The HSC device assembled by them exhibits the maximum energy and power densities of 52.9 Wh/kg and 8579.5 W/kg. Moreover, the device maintains 82.8% specific capacity after 5000 cycles.

Biological synthesis of novel carbon quantum dots using Halimeda opuntia green algae with improved optical properties and electrochemical performance for possible energy storage applications

Carbon quantum dots, known to be nanomaterials with zero dimension have recently emerged as excellent materials for versatile technological applications in optoelectronics, energy storage and conversions. They possess simple and low-cost synthesis methods with outstanding optical properties, low toxicity, high biocompatibility with favourable charge transfer and electronic conductivity. Recently, much attention has been paid towards the eco-friendly synthesis of carbon dots from sources such as biomass as the precursors which provides solution to global challenges of waste management. Carbon quantum dots (CQDs) have attracted greater attention as energy storage materials because of their unique electrical properties and ability to host various functional groups on the electrode surface. Recently CQDs have been utilized as electrode materials towards enhancing the energy density of supercapacitors. Herein we report the biological synthesis of CQDs using biomass such as green algae of Halimeda opuntia. The obtained CQDs were characterized by High Resolution Transmission electron microscopy (HR-TEM), X-ray Diffraction (XRD), Fourier Transform-Infra Red (FT-IR) spectroscopy, UV-Vis Spectroscopy. The fluorescence properties were analysed through emission spectra. The electrochemical performance of CQDs as a supercapacitor were studied using modified Glassy Carbon Electrode (GCE). The CQDs synthesized from Halimeda opuntia green algae exhibits a specific capacitance of 311 F g−1. Due to excellent optical properties and electrochemical performances, these CQDs synthesized using Halimeda opuntia could potentially be used in energy storage and conversion applications.

Boosting energy density of the aqueous supercapacitors by employing trifluoroacetic acid as a novel high voltage electrolyte

An effective way to increase the energy density of supercapacitors is to develop stable electrolytes with high operating potential. In this work, trifluoroacetic acid (TFA) is first employed as an aqueous acidic electrolyte with a stable operating potential of 1.4 V, a 40 % improvement in operating potential is achieved compared to the traditional acidic aqueous electrolyte. To match the TFA electrolyte, a biomass-derived hierarchical porous carbon (HPC) with a tailored pore size and ultra-large specific surface area of up to 3649.4 m2 g−1 is fabricated, which delivers a surprising specific capacitance of up to 625 F g−1 at 1 A g−1. The symmetric supercapacitor device built up by using the TFA electrolyte and the prepared electrode material can be operated stably at 1.4 V and reserve 96.6 % of initial specific capacitance after 30,000 cycles. Meanwhile, a large energy density of 19.5 Wh kg−1 at 347 W kg−1 and 19.49 Wh kg−1 at 340 W kg−1 can be delivered for the assembled normal symmetric supercapacitor and the solid-state supercapacitor, respectively. Compared to the supercapacitors using the conventional H2SO4 electrolyte, the energy density of the supercapacitor using the TFA electrolyte can be enhanced by 2.26 times without sacrificing the high-power density and outstanding cycle stability. The remarkable improvement in energy density for aqueous supercapacitors by this simple and feasible method would contribute to promoting their practical application in modern electrochemical energy storage systems.

Binder-free hybrid cobalt-based sulfide/oxide nanoarrays toward enhanced energy storage performance for hybrid supercapacitors

Cobalt-based materials have excellent electrochemical properties in theory and show great potential for improving the energy density of supercapacitors. The facile synthesis strategy and enhanced energy storage performance of self-supported cobalt-based sulfide/oxide nanoarrays (Co-S/Co-O) are demonstrated for hybrid supercapacitors in this work. In the Co-S/Co-O nanoarrays, the CoS sulfide and CoO oxide are intertwined with each other to form a whole, bringing positive synergistic effect for Faraday reaction and rapid electrons/ions transfer. As expected, Co-S/Co-O has higher specific capacity (1065 C g−1 at 1 A g−1) than CoS (176 C g−1) and CoO (702.5 C g−1). Furthermore, the Co-S/Co-O hybrid supercapacitor assembled with nitrogen-doped graphene as negative electrode shows higher specific capacitance (110 F g−1 at 1 A g−1) and specific energy (39.38 Wh kg−1 at a specific power of 800 W kg−1). The results show that Co-S/Co-O hybrid materials have great potential for energy storage applications. This work also provides a good strategy for improving the charge storage capacity of cobalt-based materials.

A Novel Aqueous Asymmetric Supercapacitor based on Pyrene-4,5,9,10-Tetraone Functionalized Graphene as the Cathode and Annealed Ti3 C2 Tx MXene as the Anode.

Asymmetric supercapacitors (ASCs), employing two dissimilar electrode materials with a large redox peak position difference as cathode and anode, have been designed to further broaden the voltage window and improve the energy density of supercapacitors. Organic molecule based electrodes can be constructed by combining redox-active organic molecules with conductive carbon-based materials such as graphene. Herein, pyrene-4,5,9,10-tetraone (PYT), a redox-active molecule with four carbonyl groups, exhibits a four-electron transfer process and can potentially deliver a high capacity. PYT is noncovalently combined with two different kinds of graphene (Graphenea [GN] and LayerOne [LO]) at different mass ratios. The PYT-functionalized GN electrode (PYT/GN 4-5) possesses a high capacity of 711 F g-1 at 1 A g-1 in 1M H2 SO4 . To match with the PYT/GN 4-5 cathode, an annealed-Ti3 C2 Tx (A-Ti3 C2 Tx ) MXene anode with a pseudocapacitive character is prepared by pyrolysis of pure Ti3 C2 Tx . The assembled PYT/GN 4-5//A-Ti3 C2 Tx ASC delivers an outstanding energy density of 18.4Wh kg-1 at a power density of 700W kg-1 . The PYT-functionalized graphene holds great potential for high-performance energy storage devices.

High Mass-Loading Biomass-Based Porous Carbon Electrodes for Supercapacitors: Review and Perspectives.

Biomass-based porous carbon (BPC) with renewability and flexible nano/microstructure tunability has attracted increasing attention as efficient and cheap electrode materials for supercapacitors. To meet commercial needs, high mass-loading electrodes with high areal capacitance are preferred when designing supercapacitors. The increased mass percentage of active materials can effectively improve the energy density of supercapacitors. However, as the thickness of the electrode increases, it will face the following challenges including severely blocked ion transport channels, poor charging dynamics, poor electrode structural stability, and complex preparation processes. A bridge between theoretical research and practical applications of BPC electrodes for supercapacitors needs to be established. In this review, the advances of high mass-loading BPC electrodes for supercapacitors are summarized based on different biomass precursors. The key performance evaluation parameters of the high mass-loading electrodes are analyzed, and the performance influencing factors are systematically discussed, including specific surface area, pore structure, electrical conductivity, and surface functional groups. Subsequently, the promising optimization strategies for high mass-loading electrodes are summarized, including the structure regulation of electrode materials and the optimization of other supercapacitor components. Finally, the major challenges and opportunities of high mass-loading BPC electrodes in the future are discussed and outlined.

Employing Redox‐Active Additives for Enhanced Charge Polarization and Twofold Higher Energy Density in Supercapacitor

AbstractRemarkable improvement in the polarization and charge transport at the solid–solid electrode–electrolyte interface due to the incorporation of a redox‐active additive sodium molybdate (Na2MoO4) is demonstrated. The presence of the electrochemically active oxide center along with Na+facilitates the hopping‐based charge transport of the ionic liquid leading to higher ionic conductivity and a twofold increase in specific capacitance (0.009 to 0.018 F cm−2). This drives a 200% increase in the energy density (0.76–1.7 µW h cm−2) and a 2.5 times improvement in the rate capability (10 000 mV s−1) of the solid‐state supercapacitor. Importantly, the power density, non‐Faradic nature, and cyclability remain unaltered, resulting in performance exceeding several solid‐state and liquid electrolyte‐based supercapacitors. Thus, the results established here through the use of redox‐active additive establish the robustness of the approach and practicality of the resulting device besides providing transformative opportunities in tuning the performance of solid‐state devices.

Recent Progress and Future Directions of Biomass-Derived Hierarchical Porous Carbon: Designing, Preparation, and Supercapacitor Applications

In the past decades, fossil energy depletion, environmental pollution, and greenhouse gas emissions have resulted in serious health threats and ecological imbalances, which prompt researchers to explore green and sustainable supercapacitor energy storage and conversion systems. Biomass is a promising renewable energy source to use for biomass porous carbon for supercapacitor devices because it is renewable and has abundant reserves, a low price, and low pollution carbon energy. To date, although some reports have screened different biomass precursors, carbonization methods, and activation strategies and mechanisms, a comprehensive evaluation and critical review of the correlation among biomass porous carbon properties, including pore structure and surface chemistry, and electrochemical energy storage performances of supercapacitors are absent from a multidisciplinary assessment perspective. Therefore, in this review, we summarize recent advances in the biomass porous carbon synthesis process focusing on different carbonization and activation strategies, point out the scope of applicability and advantages/disadvantages of these methods in supercapacitor applications, and reveal the reaction mechanisms and limitations for commercial production. Then, the relationships among biomass porous carbon properties, including hierarchical porous structure, surface chemistry, specific surface area, and electrochemical performances of supercapacitors are reviewed in detail, which enables researchers to prepare and design advanced materials in a more rational way and facilitates them to explore more cutting-edge energy storage materials. Finally, two effective techniques including heteroatom doping and composite material construction are reviewed to address the general problem of low supercapacitor energy density. This review demonstrates the great potential of biomass porous carbon with superior properties, provides advanced tailoring and design viewpoints for the application fields of high-performance supercapacitors, and is expected to inspire new exploration and boost the practical commercial applications of biomass-derived hierarchical porous carbon material in more energy storage and conversion fields.

Nano-flower-like porous carbon derived from soybean straw for efficient N-S co-doped supercapacitors by coupling in-situ heteroatom doping with green activation method

The interlayer nanoflower porous carbon was prepared in this paper by coupling green and sustainable liquefied with in-situ doping using soybean straw as a biomass precursor. The pore structures of the obtained samples were reasonably controlled with non-toxic potassium citrate. The specific surface area of SSL-N/S-K-800 reaches 1756.74 m2 g−1, and the microporosity is 75.38%. In the three-electrode system test, SSL-N/S-K-700 exhibits a specific capacitance of 220 F g−1 at a current density of 0.5 A g−1. Moreover, in the two-electrode system test, the SSL-N/S-K-700 assembled symmetric supercapacitor exhibits an energy density of 11.24 W h kg−1 at a power density of 400 W kg−1. Notably, excellent cycling stability (capacitance retention > 99.2%) is presented after 10,000 cycles. The superior electrochemical properties are attributed to the ion diffusion channels provided by the macropores and mesopores, and the abundant micropores can provide ion adsorption and desorption sites. Additionally, the synchronizing N S doping effectively enhances the pseudo-capacitance of the material. This work explores a green, efficient and sustainable approach for achieving high value-added utilization of waste biomass and enhancing the energy density of supercapacitors for electrochemical energy storage.

Acetaminophen: a novel redox-additive for snowballing the energy density of flexible supercapacitors

Acetaminophen is deployed as a redox-additive for the first time to enhance the energy density of supercapacitor.

Efficient fabrication of flower-like core-shell nanochip arrays of lanthanum manganate and nickel cobaltate for high-performance supercapacitors.

The low energy density issue raises serious concerns for the large-scale application of supercapacitors. However, the development and utilization of new electrode materials with a high specific capacity to improve the energy density of supercapacitors remain challenging. Herein, an LaMnO3@NiCo2O4/carbon cloth (LMO@NCO/CC) composed of a multilayer flower-like nanochip array is prepared for the first time using an efficient electrodeposition method. This novel structure exploits the high conductivity of LaMnO3/carbon cloth (LMO@CC) to provide an efficient electron transport path for the outer layer of the NiCo2O4/carbon cloth (NCO@CC) nanoarrays, broadening the potential window. Due to the unique nanostructure configuration and the strong synergistic effect of the developed LMO@NCO/CC, the prepared electrodes show excellent supercapacitor performance. At a current density of 1 A g-1, LMO@NCO/CC has a higher specific capacitance value of 942 F g-1. The application value is extended through the fabrication of asymmetric supercapacitors with a maximum energy density of 49 Wh kg-1 and excellent cycle stability (the initial capacitance value remains 106% after 10,000 cycles of charging and discharging at a high current density of 10 A g-1). Our work paves the way for the development of next-generation electrode materials for high-performance supercapacitors.

Study on applications of radio frequency nano antenna energy conversion and supercapacitors

In this paper, the study on applications of radio frequency nano antenna energy conversion and supercapacitors is presented. Radio Frequency (RF) signals are a form of electromagnetic radiation with wavelengths greater than 3 meters. Initially used in wireless communication devices like radios and walkie-talkies, RF signals have found their way into energy conversion and storage applications. When RF signals are received by an antenna with coupled capacitors and a rectifier circuit, they generate a potential difference of a few millivolts. This potential difference can be used as a stable source of energy to power low-voltage applications through ambient RF radiation, and excess energy can be stored in electrochemical storage systems like supercapacitors and lithium-ion batteries. While this technology is currently limited to low-power applications, it has immense potential in various fields such as medicine, automotive industry, military applications, and more. Researchers are currently working to improve the energy density of supercapacitors by modifying their electrode materials using nanotechnology. One promising material is lignin, derived from wood fibers, which has shown great performance in tests and is expected to be a low-cost solution for high-performance batteries and supercapacitors. As the renewable energy sector continues to advance, we can expect to see more useful applications based on RF nano antennas and micro/nano-sized supercapacitors. The work done &amp; presented in this paper is the result of the mini-project work that has been done by the first sem engineering students of the college and as such there is little novelty in it and the references are being taken from various sources from the internet, the paper is being written by the students to test their writing skills in the starting of their engineering career and also to test the presentation skills during their mini-project presentation. The work done &amp; presented in this paper is the report of the assignment / alternate assessment tool as a part and parcel of the academic assignment of the first year subject on nanotechnology &amp; IoT.

Oxygen-vacancy V2O5 ultrathin nanosheets adorned with PEDOT films as anodes for high-energy-density asymmetric supercapacitors

Oxygen-vacancy PEDOT/V2O5 nanosheets are obtained by the oxidative polymerization of EDOT on V2O5 without other oxidants. The energy density of supercapacitors composed of PEDOT/V2O5 and activated carbon reaches 65 W h kg−1.

Dielectric Modified Separators for High-Voltage and High-Rate Supercapacitors

Widening the operational voltage window (OVW) of electrolytes has long been attracting researchers’ attention as an effective solution for improving the energy density of supercapacitors (SCs). However, the application of commercial cellulose separators in SCs under high voltage is impeded because of the hygroscopic property of hydroxyl functional groups and high self-discharges. Herein, the dielectric materials poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP and TiO2 are employed to modify the surfaces of cellulose separators, which has improved the rate (100% capacitance retention at 20 A g−1) and cyclic (over 83% capacitance retention after 10000 cycles) performance of SCs significantly. In addition, the OVW of the organic electrolyte is widened from 2.7 V to 3.8 V. The possible mechanism underlying the function of dielectric materials in SCs is discussed by establishing a model and performing inferential calculation.