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Power density vs. energy density plots at 2.7 V and at 3.2 V for electrochemical supercapacitors with ILs studied. Reproduced by permission of The Electrochemical Society from ref. 257.
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Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classifi...
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... The latter is higher for DMAc (0.89 mPa s vs. 0.33 mPa s for ACN) but similar to water (0.998 mPa s) and much lower than for propylene carbonate (2.4 mPa s), a widely used alternative for ACN in organic EDLCs. It is worth mentioning that the solvent's dielectric constant (ε) is inversely proportional to the interaction energy between ions with the opposite charge and, consequently, the ability of ion-pairs formation [35]. For the solvents with lower ε, the ion-pairing in the solution is privileged. ...
The growing interest in hybrid (aqueous-organic) electrolytes for electrochemical energy storage is due to their wide stability window, improved safety, and ease of assembly that does not require a moisture-free atmosphere. When it comes to applications in electrochemical capacitors, hybrid electrolytes are expected to fill the gap between high-voltage organic systems and their high discharge rate aqueous counterparts. This article discusses the potential applicability of aqueous-organic electrolytes utilizing water/N,N-dimethylacetamide (DMAc) solvent mixture, and sodium perchlorate as a source of charge carriers. The hydrogen bond formation between H 2 O and DMAc (mole fraction x DMAc = 0.16) is shown to regulate the original water and cation solvation structure, thus reducing the electrochemical activity of the primary aqueous solution both in the hydrogen (HER) and oxygen (OER) evolution reactions region. As a result, an electrochemical stability window of 3.0 V can be achieved on titanium electrodes while providing reasonable ionic conductivity of 39 mS cm −1 along with the electrolyte's flame retardant and anti-freezing properties. Based on the diagnostic electrochemical studies, the operation conditions for carbon/carbon capacitors have been carefully optimized to adjust the potential ranges of the individual electrodes to the electrochemical stability region. The system with the appropriate electrode mass ratio (m + /m − = 1.51) was characterized by a wide operating voltage of 2.0 V, gravimetric energy of 13.2 Wh kg −1 , and practically a 100% capacitance retention after 10,000 charge-discharge cycles. This translates to a significant rise in the maximum energy of 76% when compared to the aqueous counterpart. Additionally, reasonable charge-discharge rates and antifreeze properties of the developed electrolyte enable application in a broad temperature range down to −20 • C, which is demonstrated as well.
... This allows for greater capacitance (more significant charge storage) than is feasible with ordinary capacitors. The main essential components of a SC include porous electrode material, current collector, separator, and electrolyte (6)(7)(8)(9). Recently, the materials utilized for these components have not been so environmentally friendly. ...
Energy conversion and storage devices (ECSDs) made from clean, green and eco-friendly agricultural/bio waste is achieving more attention of researchers/scientists due to its recyclability, low cost, sustainability, and excellent supercapacitance performance. The role of green electrolytes (GEs) (such as, quasi/novel solid), separators, current collectors, and electrode materials (for instance, biomass waste-derived from activated carbon (AC), reduced graphene-oxide (rGO), metal-oxides (MOs), metal-organic frameworks (MOFs), and conducting polymers (CPs)) for ECSDs is highlighted in this chapter. The depletion of energy supplies and trashing of agricultural waste has become a worldwide concern, throbbing the world’s economy and ecosystem via the fuel crisis and pollution and hence the idea of Green/Eco-Friendly Supercapacitors (GSs) is pointed out in this chapter. In the last section, the future research prospects and challenges of green electrode-electrolyte based ECSDs at industrial scale for energy sector are also projected, keeping in view their health related concerns and disposal.
... In contrast, an alternative subclass of supercapacitor, pseudo-capacitor, offers a route to store more charges than porous carbon through Faradaic reactions [4,5]. For example, common transition metal oxides [6][7][8] and conductive polymers [9,10] could theoretically provide specific capacity ranging from hundreds to over one thousand C g −1 via reversible surface redox reactions. However, low electrical conductivity and sluggish ion diffusion in the bulk active material have stifled power performance and limited the utilization of their theoretical storage capacity thus far [7,9]. ...
Supercapacitors have long suffered from low energy density. Here, we present a high-energy, high-safety, and temperature-adaptable aqueous proton battery utilizing two-dimensional Ti3C2Tx MXenes as anode materials. Additionally, our work aims to provide further insights into the energy storage mechanism of Ti3C2Tx in acid electrolytes. Our findings reveal that the ion transport mechanism of Ti3C2Tx remains consistent in both H2SO4 and H3PO4 electrolytes. The mode of charge transfer depends on its terminal groups. Specifically, the hydrogen bonding network formed by water molecules adsorbed by hydroxyl functional groups under van der Waals forces enables charge transfer in the form of naked H+ through the Grotthuss mechanism. In contrast, the hydrophobic channel formed by oxygen and halogen terminal groups facilitates rapid charge transfers in the form of hydronium ion via the vehicle mechanism, owing to negligible interfacial effect. Herein, we propose an aqueous proton battery based on porous hydroxy-poor Ti3C2Tx MXene anode and pre-protonated CuII[FeIII(CN)6]2/3∙4H2O (H-TBA) cathode in a 9.5 M H3PO4 solution. This proton battery operates through hydrated H+/H+ transfer, leading to good electrochemical performance, as evidenced by 26 Wh kg−1 energy density and 162 kW kg−1 power density at room temperature and an energy density of 17 Wh kg−1 and a power density of 7.4 kW kg−1 even at −60 °C.
... The graphite electrode (1x1 cm 2 area) was loaded with the resulting slurry with a dropper and placed in the oven to dry for 24 hr at 60 • C. After 24 hr, the graphite electrode containing slurry was immersed in aqueous 1 M H 2 SO 4 electrolytic solution [53,54]. All the studies of the samples were done in 1 M H 2 SO 4 electrolyte. ...
... ). nc/4.0/ -http://creativecommons.org/licenses/by ( The performance of the double electrolytic capacitor using them is not high [50]. Many studies conducted by recent researchers include that flexible supercapacitors, in which the electrolyte is in the solid state, have an important role in many applications, especially folding, because they are resistant to leakage, inexpensive, easy to pack, and have good mechanical stability. ...
Flexible supercapacitors (FSCs), especially wearable ones, have become a hotspot of research because of their advantages such as energy density, high specific capacitance, good mechanical properties, decent stability, and eco-friendliness. The storage mechanism in FSCs is either a faradaic mechanism in pseudocapacitors (PCs) or a non-faradaic mechanism as in double-layer supercapacitors (ELSCs). This review summarized the research progress for manufacturing electrodes from various types of materials, whereas carbon, metal oxides, or conductive polymers are utilized as electrodes. An overview of what researchers have performed in changing the original shape of materials and combining them to obtain flexible electrodes with good electrochemical performances. The review includes the presence of different types of electrolytes in the FSCs structure. Perspectives on the direction of future development of research in the field of FSCs are also discussed.
... In the present case, the rapid increase in peak current beyond 2.5 V is associated with the electrolyte decomposition, oxidation of the electrode surface, and evolution of gases at higher potentials. [74,75] The EIS plot of the device in the frequency range of 100 kHz to 100 mHz exhibited a small semicircle at higher frequencies (lower R ct ) and a linear response at lower frequencies attributed to the capacitive behavior of the electrode ( Figure S6). The GCD measurements were performed up to a 2 and 2.2 V voltage limit, as shown in Figure 4b, to evaluate the actual capacitance performance. ...
Hybrid supercapacitors (HSCs) bridge the unique advantages of batteries and capacitors and are considered promising energy storage devices for hybrid vehicles and other electronic gadgets. Lithium‐ion capacitors (LICs) have attained particular interest due to their higher energy and power density than traditional supercapacitor devices. The limited voltage window and the deterioration of anode materials upsurged the demand for efficient and stable electrode materials. Two‐dimensional (2D) molybdenum sulfide (MoS2) is a promising candidate for developing efficient and durable LICs due to its wide lithiation potential and unique layer structure, enhancing charge storage efficiency. Modifying the extrinsic features, such as the dimensions and shape at the nanoscale, serves as a potential path to overcome the sluggish kinetics observed in the LICs. Herein, the MoS2 nanoflowers have been synthesized through a hydrothermal route. The developed LIC exhibited a specific capacitance of 202.4 F g⁻¹ at 0.25 A g⁻¹ and capacitance retention of >90 % over 5,000 cycles. Using an ether electrolyte improved the voltage window (2.0 V) and enhanced the stability performance. The ex‐situ material characterization after the stability test reveals that the storage mechanism in MoS2‐LICs is not diffusion‐controlled. Instead, the fast surface redox reactions, especially intercalation/deintercalation of ions, are more prominent for charge storage.
... During charging-discharging, energy dissipation was eliminated for lower internal resistance materials, and as a result, the energy storage performance improved. 87,91 So, to fabricate power-saving supercapacitors, the MoS 2 /MnO 2 (6 wt%) nanocomposite is preferable. The energy density (E) and power density (P) were determined from the GCD curves of the synthesized samples by using eqn (4) and (5), respectively 92 ...
In this study, an MoS2/MnO2 nanocomposite electrode with a novel 3D nanoflower/1D nanorod architecture is effectively synthesized using a straightforward, cost-effective hydrothermal process. The addition of the 1D MnO2 nanorod offers a structural backbone, while the 3D MoS2 nanoflower generates additional reactive active sites. The hybrid structure makes fast electron and ion movement possible, which also increases the capacity for charge collection. This leads to 199.12 F g⁻¹ specific capacitance at 40 mA g⁻¹ in a designed 3D-1D MoS2/MnO2(6 wt%) electrode and exceptional rate capability with a tremendous cycling life (95% capacitance retention after 10 000 cycles). This discovery paves the way for the low-cost and straightforward construction of a hierarchical nanocomposite electrode with improved charge storage and electrical conductivity in energy storage applications like supercapacitors.
... These methods generally help characterize the total solutes in solutions. Still, they cannot differentiate between the contributing ionic sources of these measurements-for example, the ionic conductivity of Na + (50.11 S cm 2 mol À1 ) versus Mg 2+ (106.12 S cm 2 mol À1 ; Zhong et al., 2015). Consequently, the reduction or loss of features critical to maintaining ecosystem integrity, such as biodiversity and microbe-mediated resource cycling, that are often attributed to the masking generic term 'salinization', may be more accurately described by an increase in a specific ionic component (Berger et al., 2019;Bogart et al., 2019;Cañedo-Argüelles et al., 2013;Clements & Kotalik, 2016;Griffith, 2014;Lo Nostro et al., 2005;Schuler & Relyea, 2018). ...
The degradation of freshwater systems by salt pollution is a threat to global freshwater resources. Salinization is commonly identified by increased specific conductance (conductivity), a proxy for salt concentrations. However, conductivity fails to account for the diversity of salts entering freshwaters and the potential implications this has on microbial communities and functions. We tested 4 types of salt pollution—MgCl 2 , MgSO 4 , NaCl, and Na 2 SO 4 —on bacterial taxonomic and functional α‐, β‐diversity of communities originating from streams in two distinct localities (Nebraska [NE] and Ohio [OH], USA). Community responses depended on the site of origin, with NE and OH exhibiting more pronounced decreases in community diversity in response to Na 2 SO 4 and MgCl 2 than other salt amendments. A closer examination of taxonomic and functional diversity metrics suggests that core features of communities are more resistant to induced salt stress and that marginal features at both a population and functional level are more likely to exhibit significant structural shifts based on salt specificity. The lack of uniformity in community response highlights the need to consider the compositional complexities of salinization to accurately identify the ecological consequences of instances of salt pollution.
... The rapid depletion or exhaustion of the world's fossil fuel reserves is the first problem. The second concern is related to environmental issues, such as general air and water pollution and rising greenhouse gas emissions [135]. Electric double-layer capacitors (EDLCs), also known as supercapacitors (SCs), or rapid surface redox reactions (named pseudocapacitors) are two ways that supercapacitors (SCs), also referred to as ultracapacitors, store energy. ...
The scientific community is becoming increasingly interested in the production of activated carbon (AC) using pyrolyzed biomass wastes as potential sustainable precursors. Both chemical and physical methods may have a significant impact on the chemical and physical properties of AC, making it suitable for a variety of applications such as water pollution treatment, CO2 capture, dye, and heavy metal (HM) removal, and energy storage. The properties of AC are significantly influenced by feedstock composition, pyrolysis conditions, and carbon activation parameters. In comparison to traditional AC, activated biochar appears to be a new potentially cost-effective, and environmentally friendly carbon material with a wide range of applications. Walnut is a well-known member of the Juglandaceae family. Walnut Shell (WS) is extremely tough and degrades very slowly, and the multiple synthesis procedures employ the shell to prepare AC. In this review article, a detailed list of products and different applications of AC from the WS is provided. The cited results explain the optimal conditions for an adsorption process, which include pH, adsorbent dosage, temperature, agitation speed, contact time, efficiency, adsorption capacity, fitting model, kinetics, and thermodynamics. In addition, it also describes the removal of a few organic compounds, and energy storage applications using parameters such as BET, different electrolytes, and specific capacitance.
... With the addition of a K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 /hydroquinone redox additive into a common electrolyte such as Na 2 SO 4 , KOH, KI, H 2 SO 4 , etc., the specific capacitance of the supercapacitor can be increased by several times that of its performance in a common electrolyte [38]. Generally, common electrolytes are electrochemically inert with no redox reactions occurring in them [39]. Whereas, in redox-additive-based electrolytes, the redox reactions take place at both the electrode surface and electrolyte, which leads to the enhancement of the supercapacitor's performance. ...
Novel flake-like Ni1−xSnxO2 particles were successfully prepared by template-free hydrothermal synthesis. The prepared samples were investigated for their properties by different characterization techniques. Scanning micrographs showed that the obtained particles consisted of nanoflakes. The X-ray diffraction results of the Ni1−xSnxO2 revealed the formation of mixed-phase Ni/SnO2 having the typical tetragonal structure of SnO2, and the cubic structure of Ni in a nanocrystalline nature. The doping with Ni had a certain influence on the host’s lattice structure of SnO2 at different doping concentrations. Confirmation of the functional groups and the elements in the nanomaterials was accomplished using FTIR and EDS analyses. The electrochemical performance analysis of the prepared nanomaterials were carried out with the help of the CV, GCD, and EIS techniques. The specific capacitance of the synthesized nanomaterials with different concentrations of Ni dopant in SnO2 was analyzed at different scanning rates. Interestingly, a 5% Ni-doped SnO2 nanocomposite exhibited a maximum specific capacitance of 841.85 F g−1 at 5 mV s−1 in a 6 M KOH electrolyte. Further, to boost the electrochemical performance, a redox additive electrolyte was utilized, which exhibited a maximum specific capacitance of 2130.33 at 5 mV s−1 and an excellent capacitance retention of 93.22% after 10,000 GCD cycles. These excellent electrochemical characteristics suggest that the Ni/SnO2 nanocomposite could be utilized as an electrode material for high-performance supercapacitors.
