Search Results (18)

The development of polymer binders with tailored functionalities and green manufacturing processes is highly needed for high-performance lithium–sulfur batteries. In this study, a readily hydrolyzable 3,9-divinyl-2,4,8,10-tetraoxaspiro-[5.5]-undecane is utilized to prepare a water-based binder. Specifically, the acrolein produced by hydrolysis undergoes in situ polymerization to form a linear polymer, while the other hydrolyzed product, pentaerythritol, physically crosslinks these polymer chains via hydrogen bonding, generating a network polymer (BTU). Additionally, gallic acid (GA), a substance derived from waste wood, is further introduced into BTU during slurry preparation, forming a biphenol-containing binder (BG) with a multi-hydrogen-bonded structure. This resilience and robust cathode framework effectively accommodate volumetric changes during cycling while maintaining efficient ion and electron transport pathways. Furthermore, the abundant polar groups in BG enable strong polysulfide adsorption. As a result, sulfur cathode with a high mass loading of 5.3 mg cm⁻² employing the BG (7:3) binder still retains an areal capacity of 4.7 mA h cm⁻² after 50 cycles at 0.1 C. This work presents a sustainable strategy for battery manufacturing by integrating renewable biomass-derived materials and eco-friendly aqueous processing to develop polymer binders, offering a green pathway to high-performance lithium–sulfur batteries. Full article

Currently, there are many infrastructures for which these design service lives are expired. These lifespans have been extended through retrofitting and strengthening. Usually, the existing reinforced concrete (RC) structures are strengthened by applying steel plate bonding and concrete enlargement methods. However, since fiber-reinforced polymer (FRP) composite materials have properties that are better than those of steel and concrete materials, i.e., being light weight, with anticorrosive material, a high ratio of strength to weight, and better workability, FRP sheet bonding methods for RC members have been developed, and practical applications have been gradually increased worldwide, statically. The methods may also have some potential to strengthen the members under impact and blast loading. In this paper, to rationally improve the impact resistance of RC beams under flexure, beams were strengthened by bonding an FRP sheet to the bottom tension side. Then, low-velocity impact loading tests (hereafter referred to as impact loading tests) using a 300 kg steel weight were carried out on the beams strengthened with carbon FRP (CFRP) sheets of different areal masses to investigate the failure mode at the ultimate state of the beams, in which the areal mass is physically similar to the amount of the sheet reinforcing RC beams and hereafter referred to as the sheet volume. Two sheet volumes (one is an areal mass of 300 g/m² having a 0.17 mm thickness and the other is of 600 g/m² having a 0.33 mm thickness) were compared, and two static failure modes, concrete crushing-intermediate crack (IC) debonding and premature IC debonding, were observed. The following results were obtained from this study: taking a static calculated moment ratio M_y/M_u of the rebar yield-moment M_y to the ultimate moment M_u for each beam, in the case of the beams having an M_y/M_u (=0.67) larger than 0.65 that went through static failure in the concrete crushing-IC debonding mode, the beams failed in sheet rupturing mode subjected to an impact load. When the sheet volume was comparatively large and a static calculated moment ratio M_y/M_u (=0.6) was less than 0.65, the beams collapsed in the premature IC debonding mode under not only static but also impact loading, and the impact resistance of the beams was enhanced with an increasing sheet volume; this increase was greater in the impact loading case than in the static loading case. Full article

Manganese-based oxides, particularly β-MnO₂, have emerged as promising cathode materials for aqueous zinc-ion batteries (ZIBs) due to their high theoretical capacity, low cost, and intrinsic safety. However, their sluggish reaction kinetics, limited active sites, and poor conductivity often lead to suboptimal electrochemical performance. To address these limitations, we propose a facile ethanol-mediated hydrothermal strategy to engineer rod-like β-MnO₂ nanostructures with tailored oxygen vacancies. By precisely adjusting ethanol addition (3–5 mL) during synthesis, oxygen vacancy concentrations were optimized to enhance electronic conductivity and active site exposure. The experimental results demonstrate that β-MnOx-2-5 synthesized with 5 mL of ethanol delivers an exceptional areal capacity of 4.87 mAh cm⁻² (348 mAh g⁻¹, 469.8 Wh kg⁻¹) at 200 mA cm⁻² under a high mass loading of 14 mg cm⁻². Further, a hybrid electrode combining oxygen-deficient β-MnO₂-x-3 (air-calcined) and structurally stable β-Mn₅O₈-y-3 (Ar-calcined) achieves a retained capacity of 3.9 mAh cm⁻² with stable cycling performance, achieving an optimal equilibrium between high capacity and long-term operational durability. Systematic characterizations (XPS, ESR, XANES, FT-EXAFS) confirm vacancy-induced electronic structure modulation, accelerating ion diffusion and redox kinetics. This scalable vacancy engineering approach, requiring only ethanol dosage control, presents a viable pathway toward industrial-scale ZIB applications. Full article

With the rapid development of the Internet of Things (IoT), there is an increasing demand for batteries with high energy and power densities. Three-dimensional microstructures present a promising approach for achieving high areal mass loading and an expanded electrochemical reaction surface. However, their high cost and complexity have hindered their widespread adoption. In this study, hierarchical porous electrodes integrated with conformal ultrathin nanosheets were fabricated to enhance reaction kinetics. The hierarchical porous skeleton provides a continuous pathway for electron transport and electrolyte diffusion, while the amorphous vanadium oxide (α-VO_x) nanosheets offer short ion diffusion channels and a large electrochemical surface area. Additionally, the internal space of the hierarchical structure accommodates substantial growth of the α-VO_x nanosheets, thereby supporting high mass loading and preserving areal capacity. The resulting hierarchical electrode structure demonstrates a high energy density of 0.49 mAh cm⁻² at 1 mA cm⁻² and an ultrahigh power density of 410 mW cm⁻² at 250 mA cm⁻². The assembled microbattery, using lithium metal as the anode, is encapsulated with a novel packaging process. This microbattery can power an electronic clock for up to 18 h on a single charge, retaining 75% of its initial capacity after 180 cycles. Full article

Compared to traditional lithium metal batteries, anode-free lithium metal batteries use bare current collectors as an anode instead of Li metal, making them highly promising for mass production and achieving high-energy density. The current collector, as the sole component of the anode, is crucial in lithium deposition-stripping behavior and greatly impacts the rate of Li depletion from the cathode. In this study, to investigate the lithiophilicity effect of the current collector on the solid electrolyte interface (SEI) film construction and cycling performance of anode-free lithium batteries, various lightweight paper-based current collectors were prepared by electroless plating Cu and lipophilic Ag on low-dust paper (LDP). The areal densities of the as-prepared LDP@Cu, LDP@Cu-Ag, and LDP@Ag were approximately 0.33 mg cm⁻². The use of lipophilic Ag-coated collectors with varying loadings allowed for the regulation of lipophilicity. The impacts of these collectors on the distribution of SEI components and Li depletion rate in common electrolytes were investigated. The findings suggest that higher loadings of lipophilic materials, such as Ag, on the current collector increase its lipophilicity but also lead to significant Li depletion during the cycling process in full-cell anode-free Li metal batteries. Thus, moderately lithiophilic current collectors, such as LDP@Cu-Ag, show more potential for Li deposition and striping and stable SEI with a low speed of Li depletion. Full article

Ti₃C₂T_x MXene, as a common two-dimensional material, has a wide range of applications in electrochemical energy storage. However, the surface forces of few-layer or monolayer Ti₃C₂T_x MXene lead to easy agglomeration, which hinders the demonstration of its performance due to the characteristics of layered materials. Herein, we report a facile method for preparing monolayer Ti₃C₂T_x MXene on nickel foam to achieve a self-supporting structure for supercapacitor electrodes under high electrostatic fields. Moreover, the specific capacitance varies with the deposition of different-concentration monolayer Ti₃C₂T_x MXene on nickel foam. As a result, Ti₃C₂T_x/NF has a high specific capacitance of 319 mF cm⁻² at 2 mA cm⁻² and an excellent long-term cycling stability of 94.4% after 7000 cycles. It was observed that the areal specific capacitance increases, whereas the mass specific capacitance decreases with the increasing loading mass. Attributable to the effect of the high electrostatic field, the self-supporting structure of the Ti₃C₂T_x/NF becomes denser as the concentration of the monolayer Ti₃C₂T_x MXene ink increases, ultimately affecting its electrochemical performance. This work provides a simple way to overcome the agglomeration problem of few-layer or monolayer MXene, then form a self-supporting electrode exhibiting excellent electrochemical performance. Full article

With the merits of having excellent safety, being low cost and being environmentally friendly, zinc-ion hybrid supercapacitors (ZHSCs) are expected to be widely used in large-scale energy storage and flexible wearable devices. However, limited by their sluggish kinetic process, ZHSCs suffer from low-specific capacity and poor cycling stability at high cathode mass loading. Herein, a novel designed oxygen-rich hierarchical porous carbon (HPOC) is obtained by a one-step strategy of synchronous activation and templated for high-performance ZHSCs. The fabricated ZHSCs with HPOCs show significant improvement in Zn-ion storage capability, with a capacity of 209.4 mAh g⁻¹ at 0.1 A g⁻¹ and 108.3 mAh g⁻¹ at 10 A g⁻¹. Additionally, the cycling stability is excellent, with 92.3% retention after 4000 cycles. Furthermore, an impressive areal capacity of 1.7 mAh cm⁻² is achieved, even with a high mass loading of 12.5 mg cm⁻². More importantly, the flexible quasi-solid state ZHSCs also show a considerable capability (183.5 mAh g⁻¹ at 0.1 A g⁻¹) and a high energy density of 178.0 Wh kg⁻¹. This promising result suggests a valuable route to produce functional nanocarbon materials for zinc storage applications. Full article

Ti₃C₂T_x–Fe₃O₄–carbon nanotube composites were prepared for electrochemical energy storage in the negative electrodes of supercapacitors. The electrodes show a remarkably high areal capacitance of 6.59 F cm⁻² in a neutral Na₂SO₄ electrolyte, which was obtained by the development of advanced nanofabrication strategies and due to the synergistic effect of the individual components. Enhanced capacitance was achieved using the in-situ synthesis method for the Fe₃O₄ nanoparticles. The superparamagnetic behavior of the Fe₃O₄ nanoparticles facilitated the fabrication of electrodes with a reduced binder content. Good mixing of the components was achieved using a celestine blue co-dispersant, which adsorbed on the inorganic components and carbon nanotubes and facilitated their co-dispersion and mixing. The capacitive behavior was optimized by the variation of the electrode composition and mass loading in a range of 30–45 mg cm⁻². An asymmetric device was proposed and fabricated, which contained a Ti₃C₂T_x–Fe₃O₄–carbon nanotube negative electrode and a polypyrrole–carbon nanotube positive electrode for operation in an Na₂SO₄ electrolyte. The asymmetric supercapacitor device demonstrated high areal capacitance and excellent power-density characteristics in an enlarged voltage window of 1.6 V. This investigation opens a new avenue for the synthesis and design of MXene-based asymmetric supercapacitors for future energy storage devices. Full article

Lithium sulfur batteries are suitable for drones due to their high gravimetric energy density (2600 Wh/kg of sulfur). However, on the cathode side, high specific capacity with high sulfur loading (high areal capacity) is challenging due to the poor conductivity of sulfur. Shuttling of Li-sulfide species between the sulfur cathode and lithium anode also limits specific capacity. Sulfur-carbon composite active materials with encapsulated sulfur address both issues but require expensive processing and have low sulfur content with limited areal capacity. Proper encapsulation of sulfur in carbonaceous structures along with active additives in solution may largely mitigate shuttling, resulting in cells with improved energy density at relatively low cost. Here, composite current collectors, selected binders, and carbonaceous matrices impregnated with an active mass were used to award stable sulfur cathodes with high areal specific capacity. All three components are necessary to reach a high sulfur loading of 3.8 mg/cm² with a specific/areal capacity of 805 mAh/g/2.2 mAh/cm². Good adhesion between the carbon-coated Al foil current collectors and the composite sulfur impregnated carbon matrices is mandatory for stable electrodes. Swelling of the binders influenced cycling retention as electroconductivity dominated the cycling performance of the Li-S cells comprising cathodes with high sulfur loading. Composite electrodes based on carbonaceous matrices in which sulfur is impregnated at high specific loading and non-swelling binders that maintain the integrated structure of the composite electrodes are important for strong performance. This basic design can be mass produced and optimized to yield practical devices. Full article

In this study, we are reporting the impact of the incorporation of ferroelectric nanoparticles (FNPs), such as BaTiO₃ (BTO), BiFeO₃ (BFO), Bi₄NdTi₃Fe_0.7Ni_0.3O₁₅ (BNTFN), and Bi₄NdTi₃Fe_0.5Co_0.5O₁₅ (BNTFC), as well as the mass loading of sulfur to fabricated solvent-free sulfur/holey graphene-carbon black/polyvinylidene fluoride (S/FNPs/CBhG/PVDF) composite electrodes to achieve high areal capacity for lithium-sulfur (Li-S) batteries. The dry-press method was adopted to fabricate composite cathodes. The hG, a conductive and lightweight scaffold derived from graphene, served as a matrix to host sulfur and FNPs for the fabrication of solvent-free composites. Raman spectra confirmed the dominant hG framework for all the composites, with strong D, G, and 2D bands. The surface morphology of the fabricated cathode system showed a homogeneous distribution of FNPs throughout the composites, confirmed by the EDAX spectra. The observed Li⁺ ion diffusion coefficient for the composite cathode started at 2.17 × 10⁻¹⁶ cm²/s (S₂₅(CBhG)₆₅PVDF₁₀) and reached up to the highest value (4.15 × 10⁻¹⁵ cm²/s) for S₂₅BNTFC₅(CBhG)₆₀PVDF₁₀. The best discharge capacity values for the S₂₅(CBhG)₆₅PVDF₁₀ and S₂₅BNTFC₅(CBhG)₆₀PVDF₁₀ composites started at 1123 mAh/g_s and 1509 mAh/g_s and dropped to 612 mAh/g_s and 572 mAh/g_s, respectively, after 100 cycles; similar behavior was exhibited by the other composites that were among the best. These are better values than those previously reported in the literature. The incorporation of ferroelectric nanoparticles in the cathodes of Li-S batteries reduced the rapid formation of polysulfides due to their internal electric fields. The areal capacity for the S₂₅(CBhG)₆₅PVDF₁₀ composites was 4.84 mAh/cm² with a mass loading of 4.31 mg_s/cm², while that for the S₂₅BNTFC₅(CBhG)₆₀PVDF₁₀ composites was 6.74 mAh/cm² with a mass loading of 4.46 mg_s/cm². It was confirmed that effective FNP incorporation within the S cathode improves the cycling response and stability of cathodes, enabling the high performance of Li-S batteries. Full article

The shuttling effect of soluble lithium polysulfides (LiPSs) and the sluggish conversion kinetics of polysulfides into insoluble Li₂S₂/Li₂S severely hinders the practical application of Li-S batteries. Advanced catalysts can capture and accelerate the liquid–solid conversion of polysulfides. Herein, we try to make use of bismuth tantalum oxide with oxygen vacancies as an electrocatalyst to catalyze the conversion of LiPSs by reducing the sulfur reduction reaction (SRR) nucleation energy barrier. Oxygen vacancies in Bi₄TaO₇ nanoparticles alter the electron band structure to improve instinct electronic conductivity and catalytic activity. In addition, the defective surface could provide unsaturated bonds around the vacancies to enhance the chemisorption capability with LiPSs. Hence, a multidimensional carbon (super P/CNT/Graphene) standing sulfur cathode is prepared by coating oxygen vacancies Bi₄TaO_7−x nanoparticles, in which the multidimensional carbon (MC) with micropores structure can host sulfur and provide a fast electron/ion pathway, while the outer-coated oxygen vacancies with Bi₄TaO_7−x with improved electronic conductivity and strong affinities for polysulfides can work as an adsorptive and conductive protective layer to achieve the physical restriction and chemical immobilization of lithium polysulfides as well as speed up their catalytic conversion. Benefiting from the synergistic effects of different components, the S/C@Bi₃TaO_7−x coin cell cathode shows superior cycling and rate performance. Even under a high level of sulfur loading of 9.6 mg cm⁻², a relatively high initial areal capacity of 10.20 mAh cm⁻² and a specific energy density of 300 Wh kg⁻¹ are achieved with a low electrolyte/sulfur ratio of 3.3 µL mg⁻¹. Combined with experimental results and theoretical calculations, the mechanism by which the Bi₄TaO₇ with oxygen vacancies promotes the kinetics of polysulfide conversion reactions has been revealed. The design of the multiple confined cathode structure provides physical and chemical adsorption, fast charge transfer, and catalytic conversion for polysulfides. Full article

This investigation addresses the challenges in the development of efficient nanostructured Mn₃O₄ cathodes for supercapacitors. A high areal capacitance and the ability to avoid a time-consuming activation procedure for electrodes with high active mass loading of 40 mg cm⁻² are reported. This facilitates practical applications of Mn₃O₄ based electrodes. The highest capacitance of 6.11 F cm⁻² (153 F g⁻¹) is obtained from cyclic voltammetry at a scan rate of 2 mV s⁻¹ and 6.07 F cm⁻² (151.9 F g⁻¹) from the chronopotentiometry at a current density of 3 mA cm⁻² in a potential window of 0.9 V in a neutral Na₂SO₄ electrolyte. The new approach is based on the application of rhamnolipids (RL) as a capping agent for the synthesis of Mn₃O₄ particles and a co-dispersant for Mn₃O₄ and carbon nanotubes, which are used as conductive additives. The size and shape of the Mn₃O₄ particles are influenced by RL. The enhanced performance of the electrodes is linked to the chemical structure and properties of RL molecules, which exert influence on Mn₃O₄ particle size and shape during synthesis, reduce agglomeration, facilitate RL adsorption on Mn₃O₄ and carbon nanotubes, and influence their co-dispersion and mixing at the nanometric scale. Full article

The purpose of this study is to highlight the influence of some fabrication parameters, such as mass loading and porosity, which are not really elucidated and standardized during the realization of electrodes for supercapacitors, especially when using metal oxides as electrode materials. Electrode calendering, as one stage during the fabrication of electrodes, was carried out step-by-step on manganese dioxide electrodes to study the decreasing porosity effect on the electrochemical performance of a MnO₂ symmetric device. One other crucial parameter, the mass loading, which has to be understood and well used for realistic supercapacitors, was investigated concurrently. Gravimetric, areal and volumetric capacitances are highlighted, varying the porosity for low-, medium- and large-mass loading. Low-loading leads to the best specific capacitances but is not credible for realistic supercapacitors, except for microdevices. Down 50% porosities after calendering, capacitances are increased and become stable faster, suggesting a faster wettability of the dense electrodes by the electrolyte, especially for high-mass loading. EIS experiments performed on electrodes without and with calendering lead to a significant decrease of the device’s time response, especially at high loading. A high-mass loading device seems to work as a power battery, whereas electrode calendaring, which allows decreasing the time response, leads to an electrical behavior closer to that expected for a supercapacitor. Full article

MXenes, such as Ti₃C₂T_x, are promising materials for electrodes of supercapacitors (SCs). Colloidal techniques have potential for the fabrication of advanced Ti₃C₂T_x composites with high areal capacitance (C_S). This paper reports the fabrication of Ti₃C₂T_X-Fe₃O₄-multiwalled carbon nanotube (CNT) electrodes, which show C_S of 5.52 F cm⁻² in the negative potential range in 0.5 M Na₂SO₄ electrolyte. Good capacitive performance is achieved at a mass loading of 35 mg cm⁻² due to the use of Celestine blue (CB) as a co-dispersant for individual materials. The mechanisms of CB adsorption on Ti₃C₂T_X, Fe₃O₄, and CNTs and their electrostatic co-dispersion are discussed. The comparison of the capacitive behavior of Ti₃C₂T_X-Fe₃O₄-CNT electrodes with Ti₃C₂T_X-CNT and Fe₃O₄-CNT electrodes for the same active mass, electrode thickness and CNT content reveals a synergistic effect of the individual capacitive materials, which is observed due to the use of CB. The high C_S of Ti₃C₂T_X-Fe₃O₄-CNT composites makes them promising materials for application in negative electrodes of asymmetric SC devices. Full article

The ability to achieve high areal capacitance for oxide-based supercapacitor electrodes with high active mass loadings is critical for practical applications. This paper reports the feasibility of the fabrication of Mn₃O₄-multiwalled carbon nanotube (MWCNT) composites by the new salting-out method, which allows direct particle transfer from an aqueous synthesis medium to a 2-propanol suspension for the fabrication of advanced Mn₃O₄-MWCNT electrodes for supercapacitors. The electrodes show enhanced capacitive performance at high active mass loading due to reduced particle agglomeration and enhanced mixing of the Mn₃O₄ particles and conductive MWCNT additives. The strategy is based on the multifunctional properties of octanohydroxamic acid, which is used as a capping and dispersing agent for Mn₃O₄ synthesis and an extractor for particle transfer to the electrode processing medium. Electrochemical studies show that high areal capacitance is achieved at low electrode resistance. The electrodes with an active mass of 40.1 mg cm⁻² show a capacitance of 4.3 F cm⁻² at a scan rate of 2 mV s⁻¹. Electron microscopy studies reveal changes in electrode microstructure during charge-discharge cycling, which can explain the increase in capacitance. The salting-out method is promising for the development of advanced nanocomposites for energy storage in supercapacitors. Full article