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Binary transition metal oxide complexes (BTMOCs) in three-dimensional (3D) layered structures show great promise as electrodes for supercapacitors (SCs) due to their diverse oxidation states, which contribute to high specific capacitance. However, the synthesis of BTMOCs with 3D structures remains challenging yet crucial for their application. In this study, we present a novel approach utilizing a single-step hydrothermal technique to fabricate flower-shaped microspheres composed of a NiCo-based complex. Each microsphere consists of nanosheets with a mesoporous structure, enhancing the specific surface area to 23.66 m2 g-1 and facilitating efficient redox reactions. When employed as the working electrode for supercapacitors, the composite exhibits remarkable specific capacitance, achieving 888.8 F g-1 at 1 A g-1. Furthermore, it demonstrates notable electrochemical stability, retaining 52.08% capacitance after 10,000 cycles, and offers a high-power density of 225 W·kg-1, along with an energy density of 25 Wh·kg-1, showcasing its potential for energy storage applications. Additionally, an aqueous asymmetric supercapacitor (ASC) was assembled using NiCo microspheres-based complex and activated carbon (AC). Remarkably, the NiCo microspheres complex/AC configuration delivers a high specific capacitance of 250 F g-1 at 1 A g-1, with a high energy density of 88 Wh kg-1, for a power density of 800 W kg-1. The ASC also exhibits excellent long-term cyclability with 69% retention over 10,000 charge-discharge cycles. Furthermore, a series of two ASC devices demonstrated the capability to power commercial blue LEDs for a duration of at least 40 s. The simplicity of the synthesis process and the exceptional performance exhibited by the developed electrode materials hold considerable promise for applications in energy storage.
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Water electrolysis is among the recent alternatives for generating clean fuels (hydrogen). It is an efficient way to produce pure hydrogen at a rapid pace with no unwanted by-products. Effective and cheap water-splitting electrocatalysts with enhanced activity, specificity, and stability are currently widely studied. In this regard, noble metal-free transition metal-based catalysts are of high interest. Iron sulfide (FeS) is one of the essential electrocatalysts for water splitting because of its unique structural and electrochemical features. This article discusses the significance of FeS and its nanocomposites as efficient electrocatalysts for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and overall water splitting. FeS and its nanocomposites have been studied also for energy storage in the form of electrode materials in supercapacitors and lithium- (LIBs) and sodium-ion batteries (SIBs). The structural and electrochemical characteristics of FeS and its nanocomposites, as well as the synthesis processes, are discussed in this work. This discussion correlates these features with the requirements for electrocatalysts in overall water splitting and its associated reactions. As a result, this study provides a road map for researchers seeking economically viable, environmentally friendly, and efficient electrochemical materials in the fields of green energy production and storage.
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Traditional dual-ion lithium salts have been widely used in solid polymer lithium-metal batteries (LMBs). Nevertheless, concentration polarization caused by uncontrolled migration of free anions has severely caused the growth of lithium dendrites. Although single-ion conductor polymers (SICP) have been developed to reduce concentration polarization, the poor ionic conductivity caused by low carrier concentration limits their application. Herein, a dual-salt quasi-solid polymer electrolyte (QSPE), containing the SICP network as a salt and traditional dual-ion lithium salt, is designed for retarding the movement of free anions and simultaneously providing sufficient effective carriers to alleviate concentration polarization. The dual salt network of this designed QSPE is prepared through in-situ crosslinking copolymerization of SICP monomer, regular ionic conductor, crosslinker with the presence of the dual-ion lithium salt, delivering a high lithium-ion transference number (0.75) and satisfactory ionic conductivity (1.16 × 10-3 S cm-1 at 30 °C). Comprehensive characterizations combined with theoretical calculation demonstrate that polyanions from SICP exerts a potential repulsive effect on the transport of free anions to reduce concentration polarization inhibiting lithium dendrites. As a consequence, the Li||LiFePO4 cell achieves a long-cycle stability for 2000 cycles and a 90% capacity retention at 30 °C. This work provides a new perspective for reducing concentration polarization and simultaneously enabling enough lithium-ions migration for high-performance polymer LMBs.
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The new sensible thermal energy storage materials were prepared by the sintering method with low-grade pyrophyllite mineral powders as main raw materials, Suzhou clay as the sintering aid and sulfite liquors as the binder. Further, the performance of sensible thermal energy storage under different size distributions and sintering temperatures was investigated and analyzed. The results show that the optimum particle size distribution is 50:15:35, the bulk density, thermal conductivity, and specific heat capacity are the largest values, which are 1.97 g cm-3, 0.87 W m-1 K-1 and 0.63 kJ kg-1 K-1, respectively. Other properties including porosity, water absorption, flexural and compressive strength and so on are optimal under this size distribution. When the sintering temperature is 1200 °C, the material has a good thermal conductivity of 0.89 W m-1 K-1 and a high bulk density of 2.05 g cm-3. Meanwhile, the sample with the used temperature from 50 to 900 °C has the best thermal energy storage capacity of 306.29 kWh·m-3.
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New energy storage materials are an object of study within the framework of the global energy transition. The development of renewable sources is being boosted thanks to stationary energy storage systems such as redox flow batteries (RFBs). This work reports the synthesis of the cobalt-containing Keggin-type polyoxometalates [CoW12O40]6- (CoW12) and [Co(H2O)SiW11O39]6- (CoSiW11), which have previously been shown to have applicability in RFBs. These procedures were reassessed to meet the strict requirements associated with the further implementation of RFBs, including fast and affordable synthetic procedures with high reaction yields. In contrast to the lengthy and complicated synthetic approaches published to date, the optimized synthesis reported in this work enables the isolation of the pure crystalline salt of the CoW12 anion with a 75% reduction of the time of the whole reaction procedure, eliminating tedious steps such as the recrystallization and including a 20% increased yield. The control of the stoichiometry, fine-tuning of reaction conditions, and the identification of intermediate species, as well as the acidic equilibria taking place during the process, were monitored via thermal, spectroscopic, and structural analyses. In the case of the CoSiW11 anion, its preparation was based on a simple and highly efficient procedure. Moreover, promising electrochemical properties were observed with the use of the one-pot synthetic approach, in which the stoichiometric amounts of the starting reagents are dissolved in the supporting electrolyte to be directly implemented as the electrolyte for a RFB.
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All vanadium flow batteries (VFBs) are considered one of the most promising large-scale energy storage technology, but restricts by the high manufacturing cost of V3.5+ electrolytes using the current electrolysis method. Here, a bifunctional liquid fuel cell is designed and proposed to produce V3.5+ electrolytes and generate power energy by using formic acid as fuels and V4+ as oxidants. Compared with the traditional electrolysis method, this method not only does not consume additional electric energy, but also can output electric energy. Therefore, the process cost of producing V3.5+ electrolytes is reduced by 16.3%. This fuel cell has a maximum power of 0.276 mW cm-2 at an operating current of 1.75 mA cm-2 . Ultraviolet-visible spectrum and potentiometric titration identify the oxidation state of prepared vanadium electrolytes is 3.48 ± 0.06, close to the ideal 3.5. VFBs with prepared V3.5+ electrolytes deliver similar energy conversion efficiency and superior capacity retention to that with commercial V3.5+ electrolytes. This work proposes a simple and practical strategy to prepare V3.5+ electrolytes.
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Fontes de Energia Elétrica , Vanádio , Eletroquímica , Eletrólitos , OxirreduçãoRESUMO
The performance of passive and active convection indirect solar drying systems provisioned with paraffin wax as heat storage was examined while drying carrot slices. The passive indirect solar dryer (type-I) was made initially, and it was upgraded with solar-powered fans to promote mass flow rate. The new assembly was considered an active setup (type-II). Data collected during experiments were analyzed to determine performance parameters and drying kinetics. There were average improvements of 11.8%, 12.2%, and 20.7% in actual heat supply, activation energy, and specific energy consumption in type-II compared to type-I. The averaged values of collector efficiency of type-I and type-II were 59.7 and 67.8%, and the drying efficiency was 11.1 and 14.2%, respectively, while their respective improvements were 13.6 and 27.93%. It was found that the coefficients of moisture diffusion (De), heat transfer (h), mass transfer (hm), and the rate of specific moisture extraction were increased by 20.83%, 16.9%, 14.52%, and 27.8%, respectively in type-II compared to type-I. A logarithmic correlation was observed for De, h, and hm demonstrating a decrease in moisture content (MC) increased the variables. The MC was diminished from 9.13 to 0.478 kg/kg of db in 15 h in type-I and 12 h in type-II with a 3 h saving in drying time with a better drying rate in type-II. The reliability of the results was assessed with uncertainty analysis.
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Daucus carota , Temperatura Alta , Reprodutibilidade dos Testes , Luz Solar , Dessecação/métodosRESUMO
As one of the main methods for sludge treatment, recovery of renewable biogas energy by anaerobic digestion (AD) is a promising strategy to deal with the conflict between carbon neutralization and sharply increase of sewage sludge. Humic acid (HA) in sludge is a major inhibitor of biogas yields and needs to be removed or pretreated. However, as the graphene oxide-like material, HA is an ideal precursor for the preparation of energy storage materials with high performance. Based on that, this study i) proposes the extraction and utilization of HA in sludge, ii) discusses the feasibility of HA-based materials after thermal reduction as electrodes for supercapacitor, and iii) investigates the factors with positive influences on the structure and electrochemical performance. It reveals that, with a synergistic effect of purification and activation at a low mass ratio, the HA-based material exhibits superior capacitive performance with the highest specific capacitance of 186.7 F/g (at 0.05 A/g), as well as excellent rate capability and cycling stability. Sludge is verified a cheaper and more abundant precursor resource of HA for energy storage application. The results of this study are expected to provide a new green, energy-efficiency and sustainability way for sludge treatment, which has the double benefits: efficient conversion and capture of bio-energy during AD process, and high value-added utilization of HA for supercapacitor.
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Substâncias Húmicas , Esgotos , Esgotos/química , Biocombustíveis , Carbono , EletrodosRESUMO
It has long been the goal to develop rechargeable batteries with low cost and long cycling life. Polyanionic compounds offer attractive advantages of robust frameworks, long-term stability, and cost-effectiveness, making them ideal candidates as electrode materials for grid-scale energy storage systems. In the past few years, various polyanionic electrodes have been synthesized and developed for sodium storage. Specifically, doping regulation including cation and anion doping has shown a great effect in tailoring the structures of polyanionic electrodes to achieve extraordinary electrochemical performance. In this review, recent progress in doping regulation in polyanionic compounds as electrode materials for sodium-ion batteries (SIBs) is summarized, and their underlying mechanisms in improving electrochemical properties are discussed. Moreover, challenges and prospects for the design of advanced polyanionic compounds for SIBs are put forward. It is anticipated that further versatile strategies in developing high-performance electrode materials for advanced energy storage devices can be inspired.
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Long duration energy storage (LDES) is an economically attractive approach to accelerating clean renewable energy deployment. The newly emerged solid oxide iron-air battery (SOIAB) is intrinsically suited for LDES applications due to its excellent low-rate performance (high-capacity with high efficiency) and use of low-cost and sustainable materials. However, rechargeability and durability of SOIAB are critically limited by the slow kinetics in iron/iron-oxide redox couples. Here the use of combined proton-conducting BaZr0.4 Ce0.4 Y0.1 Yb0.1 O3 (BZC4YYb) and reduction-promoting catalyst Ir to address the kinetic issues, is reported. It is shown that, benefiting from the facilitated H+ diffusion and boosted FeOx -reduction kinetics, the battery operated under 550 °C, 50% Fe-utilization and 0.2 C, exhibits a discharge specific energy density of 601.9 Wh kg-1 -Fe with a round-trip efficiency (RTE) of 82.9% for 250 h of a cycle duration of 2.5 h. Under 500 °C, 50% Fe-utilization and 0.2 C, the same battery exhibits 520 Wh kg-1 -Fe discharge energy density with an RTE of 61.8% for 500 h. This level of energy storage performance promises that SOIAB is a strong candidate for LDES applications.
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Current interest toward ionic liquids (ILs) stems from some of their novel characteristics, like low vapor pressure, thermal stability, and nonflammability, integrated through high ionic conductivity and broad range of electrochemical strength. Nowadays, ionic liquids represent a new category of chemical-based compounds for developing superior and multifunctional substances with potential in several fields. ILs can be used in solvents such as salt electrolyte and additional materials. By adding functional physiochemical characteristics, a variety of IL-based electrolytes can also be used for energy storage purposes. It is hoped that the present review will supply guidance for future research focused on IL-based polymer nanocomposites electrolytes for sensors, high performance, biomedicine, and environmental applications. Additionally, a comprehensive overview about the polymer-based composites' ILs components, including a classification of the types of polymer matrix available is provided in this review. More focus is placed upon ILs-based polymeric nanocomposites used in multiple applications such as electrochemical biosensors, energy-related materials, biomedicine, actuators, environmental, and the aviation and aerospace industries. At last, existing challenges and prospects in this field are discussed and concluding remarks are provided.
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Líquidos Iônicos , Nanocompostos , Eletrólitos/química , Líquidos Iônicos/química , Polímeros/química , Solventes/químicaRESUMO
Productivity improvement is one of the high-priority areas in the development of solar stills. The present work describes the use of some low-cost energy storage materials such as sand, gravels, and black granite as potential candidates to improve the productivity of the tubular solar still (TSS). The experimental studies have been carried out at Nagpur (21.1241° N, 79.0023° E) to investigate the effects of these materials on the productivity of the TSS. Three separate TSS experimental setups have been made for each energy storage materials. These include (a) 5 kg of fine sand (0.125-0.25-mm grain size), (b) small gravels (20-30 mm), and (c) black granite (5-mm thickness) placed in the absorber basin of individual TSS setup, separately. The experiments have been performed by varying basin water depth at 0.5 cm, 1 cm, and 2 cm, for each case. The results show that for water depth of 0.5 cm, productivity of TSS-Black granite is enhanced by 10.5% and 34.88% as compared to TSS-Gravel case and TSS-Sand case, respectively. Thermal efficiency and exergy efficiency of TSS-Black granite at 0.5-cm water depth is enhanced by (32.4%, 9.8%) and (92.1%, 21.9%) as compared to TSS-Sand case and TSS-Gravel case, respectively. Furthermore, it has been estimated that the cost of production of freshwater using TSS-Black granite is lowest among all selected combinations.
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Powder materials are used in all corners of materials science, from additive manufacturing to energy storage. Scanning electron microscopy (SEM) has developed to meet morphological, microstructural and bulk chemical powder characterization requirements. These include nanoscale elemental analysis and high-throughput morphological assays. However, spatially localized powder surface chemical information with similar resolution to secondary electron (SE) imaging is not currently available in the SEM. Recently, energy filtered (EF-) SEM has been used for surface chemical characterization by secondary electron hyperspectral imaging (SEHI). This review provides a background to existing powder characterization capabilities in the low voltage SEM provided by SE imaging, EDX analysis and BSE imaging and sets out how these capabilities could be extended for surface chemical analysis by applying SEHI to powders, with particular emphasis on air and beam sensitive powder surfaces. Information accessible by SEHI, its advantages and limitations, is set into the context of other chemical characterization methods that are commonly used for assessing powder surface chemistry such as by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The applicability of existing powder preparation methods for SEM to SEHI is also reviewed. An alternative preparation method is presented alongside first examples of SEHI characterization of powder surfaces. The commercial powder materials used as examples were carbon-fiber/polyamide composite powder feedstock (CarbonMide®) used in additive manufacturing and powders consisting of lithium nickel cobalt oxide (NMC). SEHI is shown to differentiate bonding present at carbonaceous material surfaces and extract information about the work function of metal oxide surfaces. The surface sensitivity of SEHI is indicated by comparison of pristine powders to those with surface material added in preparation. A minimum spatial localization of chemical information of 55â¯nm was achieved in differentiating regions of NMC surface chemistry by distinct SE spectra.
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Elétrons , Imageamento Hiperespectral , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica , Pós/químicaRESUMO
Conjugated microporous polymers (CMPs) are promising energy storage materials owing to their rigid and cross-linked microporous structures. However, the fabrication of nano- and microstructured CMP films for practical applications is currently limited by processing challenges. Herein, we report that combined sono-cavitation and nebulization synthesis (SNS) is an effective method for the synthesis of CMP films from a monomer precursor solution. Using the SNS, the scalable fabrication of microporous and redox-active CMP films can be achieved via the oxidative C-C coupling polymerization of the monomer precursor. Intriguingly, the ultrasonic frequency used during SNS strongly affects the synthesis of the CMP films, resulting in an approximately 30% improvement in reaction yields and ca. 1.3-1.7-times enhanced surface areas (336-542 m2/g) at a high ultrasonic frequency of 180 kHz compared to those at 120 kHz. Furthermore, we prepare highly conductive, three-dimensional porous electrodes [CMP/carbon nanotube (CNT)] by a layer-by-layer sequential deposition of CMP films and CNTs via SNS. Finally, an asymmetric supercapacitor comprising the CMP/CNT cathode and carbon anode shows a high specific capacitance of 477 F/g at 1 A/g with a wide working potential window (0-1.4 V) and robust cycling stability, exhibiting 94.4% retention after 10,000 cycles.
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As a bimetal oxide, partial zinc stannate (ZnSnO3) is one of the most promising next-generation lithium anode materials, which has the advantages of low operating voltage, large theoretical capacity (1,317 mA h g-1), and low cost. However, the shortcomings of large volume expansion and poor electrical conductivity hinder its practical application. The core-shell ZnSnO3@ nitrogen-doped carbon (ZSO@NC) nanocomposite was successfully obtained by coating ZnSnO3 with polypyrrole (PPy) through in situ polymerization under ice-bath conditions. Benefiting from this unique compact structure, the shell formed by PPy cannot only effectively alleviate the volume expansion effect of ZnSnO3 but also enhance the electrical conductivity, thus, greatly improving the lithium storage performance. ZSO@NC can deliver a reversible capacity of 967 mA h g-1 at 0.1 A g-1 after 300 cycles and 365 mA h g-1 at 2 A g-1 after 1,000 cycles. This work may provide a new avenue for the synthesis of bimetal oxide with a core-shell structure for high-performance energy storage materials.
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In order to meet the growing demand for the electronics market, many new materials have been studied to replace traditional electrode materials for energy storage systems. Molybdenum oxide materials are electrode materials with higher theoretical capacity than graphene, which was originally used as anode electrodes for lithium-ion batteries. In subsequent studies, they have a wider application in the field of energy storage, such as being used as cathodes or anodes for other ion batteries (sodium-ion batteries, potassium-ion batteries, etc.), and electrode materials for supercapacitors. However, molybdenum oxide materials have serious volume expansion concerns and irreversible capacity dropping during the cycles. To solve these problems, doping with different elements has become a suitable option, being an effective method that can change the crystal structure of the materials and improve the performances. Therefore, there are many research studies on metal element doping or non-metal doping molybdenum oxides. This paper summarizes the recent research on the application of hetero-element-doped molybdenum oxides in the field of energy storage, and it also provides some brief analysis and insights.
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Value creation through waste recycling is important for a sustainable society and future. In particular, biomass, which is based on crops, is a great recyclable resource that can be converted into useful materials. Black tea is one of the most cultivated agricultural products in the world and is mostly discarded after brewing. Herein, we report the application of black tea waste biomass as electrode material for supercapacitors through the activation of biomass hydrochar under various conditions. Raw black tea was converted into hydrochar via a hydrothermal carbonization process and then activated with potassium hydroxide (KOH) to provide a large surface area and porous structure. The activation temperature and ratio of KOH were controlled to synthesize the optimal black tea carbon (BTC) with a large surface area and porosity suitable for use as electrode material. This method suggests a direction in which the enormous amount of biomass, which is simply discarded, can be utilized in the energy storage system. The synthesized optimal BTC has a large surface area of 1062 m2 and specific capacitance up to 200 Fâg-1 at 1 mVâs-1. Moreover, it has 98.8% retention of charge-discharge capacitance after 2000 cycles at the current density of 5 Aâg-1.
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Pyrochlore compounds (A 2 B 2O7) have a large applicability in various branches of science and technology. These materials are considered for use as effective ionic conductors for solid state batteries or as matrices for immobilization of actinide elements, amongst many other applications. In this contribution we discuss the simulation-based effort made in the Institute of Energy and Climate Research at Forschungszentrum Jülich and partner institutions regarding reliable computation of properties of pyrochlore and defect fluorite compounds. In the scope of this contribution, we focus on the investigation of dopant incorporation, defect formation and anion migration, as well as understanding of order-disorder transitions in these compounds. We present new, accurate simulated data on incorporation of U, Np, Pu, Am and Cm actinide elements into pyrochlores, activation energies for oxygen migration and radiation damage-induced structural changes in these materials. All the discussed simulation results are combined with available experimental data to provide a reliable description of properties of investigated materials. We demonstrate that a synergy of computed and experimental data leads to a superior characterization of pyrochlores, which could not be easily achieved by either of these methods when applied separately.
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Exploiting novel nanomaterials with fast and durable sodium/potassium ion storage capability is key to alleviate the application limitations of lithium-ion batteries. Herein, a novel energy storage material based on cobalt metaphosphate nanosheet arrays self-supported on carbon cloths [Co(PO3)2 NSs/CC] is fabricated by a two-step strategy. This rationally designed strategy avoids the preparation of the complex {Co[O2P(OtBu)2]2}n precursor, which significantly simplifies the synthesis process. The active CC acts not only as an electrically conductive substrate as usual but also as a functional basis to suppress PH3-involved reaction and to promote HPO3-involved reaction during the phosphating process, contributing to the formation of Co(PO3)2. The mutual cross-linked porous Co(PO3)2 nanosheets vertically grow on the surface of activated CC, ensuring sufficient electrolyte infiltration and fast electron transport among the electrodes. Sodium ion storage analysis for the Co(PO3)2 NSs/CC electrode reveals a multi-step reaction mechanism with high reversibility, as reflected by the high reversible capacity (667 mA h g-1 at 50 mA g-1) and excellent cyclability (with almost no capacity decay over 500 cycles). This novel electrode is also well capable of storing potassium ions, exhibiting high reversible capacity, which outperforms most reported anodes for potassium-ion batteries. The development of this novel high-performance nanomaterial would advance the performance of sodium/potassium-ion batteries toward practical applications.
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Metal-sulfur batteries (MSBs) are considered up-and-coming future-generation energy storage systems because of their prominent theoretical energy density. However, the practical applications of MSBs are still hampered by several critical challenges, i.e., the shuttle effects, sluggish redox kinetics, and low conductivity of sulfur species. Recently, benefiting from the high surface area, regulated networks, molecular/atomic-level reactive sites, the metal-organic frameworks (MOFs)-derived nanostructures have emerged as efficient and durable multifaceted electrodes in MSBs. Herein, a timely review is presented on recent advancements in designing MOF-derived electrodes, including fabricating strategies, composition management, topography control, and electrochemical performance assessment. Particularly, the inherent charge transfer, intrinsic polysulfide immobilization, and catalytic conversion on designing and engineering of MOF nanostructures for efficient MSBs are systematically discussed. In the end, the essence of how MOFs' nanostructures influence their electrochemical properties in MSBs and conclude the future tendencies regarding the construction of MOF-derived electrodes in MSBs is exposed. It is believed that this progress review will provide significant experimental/theoretical guidance in designing and understanding the MOF-derived nanostructures as multifaceted electrodes, thus offering promising orientations for the future development of fast-kinetic and robust MSBs in broad energy fields.