Search Results (118)

The demand for high-performance supercapacitors has driven extensive research into novel electrode materials with superior electrochemical properties. This study explores the supercapacitive behavior of quaternary CuNiCoZnO (CNCZO) films engineered into a three-dimensional (3D) flower-like morphology and developed on versatile substrates, including carbon cloth, stainless steel mesh, and nickel foam. The unique structural design, comprising interconnected nanosheets, enhances the electroactive surface area, facilitates ion diffusion, and improves charge storage capability. The synergistic effect of the multi-metallic composition contributes to remarkable electrochemical characteristics, including high specific capacitance, excellent rate capability, and outstanding cycling stability. Furthermore, the influence of different substrates on the electrochemical performance is systematically investigated to optimize material–substrate interactions. Electrochemical evaluations reveal outstanding specific capacitance values of 2318.5 F/g, 1993.7 F/g, and 2741.3 F/g at 2 mA/cm² for CNCZO electrodes on stainless steel mesh, carbon cloth, and nickel foam, respectively, with capacitance retention of 77.3%, 95.7%, and 86.1% over 5000 cycles. Furthermore, a symmetric device of CNCZO@Ni exhibits a peak specific capacitance of 67.7 F/g at a current density of 4 mA/cm², a power density of 717.4 W/kg, and an energy density of 25.6 Wh/kg, maintaining 84.5% stability over 5000 cycles. The straightforward synthesis of CNCZO on multiple substrates presents a promising route for the development of flexible, high-performance energy storage devices. Full article

In this work, novel sodium-intercalated vanadium oxide nanowire electrode materials (NaXV@CC) were successfully designed as cathode materials for Aqueous Zinc-Ion Batteries (AZIBs) through a two-step electrochemical process. The optimized electrode material, Na30V@CC, exhibited superior capacity, excellent rate capability, and outstanding stability. The intercalation of sodium ions into the nanowire lattice induced a significant transformation in the overall nanostructure, leading to altered nanowire morphology. This unique structural design provided abundant active sites and efficient ion transport pathways, thereby enhancing the overall electrochemical performance. The charging and discharging capacities were 343.3 and 330.4 mAh·g⁻¹ at 0.2 A·g⁻¹, respectively, and the capacity was maintained at 90 mAh·g⁻¹ at 8 A·g⁻¹. The battery demonstrated exceptional capacity retention over 3000 cycles at 5 A·g⁻¹, highlighting its long-term electrochemical stability. Moreover, the overall battery reaction was governed by a combination of diffusion and surface processes. The Na30V@CC battery system demonstrated reduced reaction impedance and improved zinc ion diffusion rates. This study offers valuable insights into enhancing the electrochemical performance of vanadium-based cathodes in AZIBs. Full article

Designing conducting polymers with novel structures is essential for electrochemical energy storage devices. Here, copolymers of s-triazine and o-aminophenol are electropolymerized from an aqueous solution onto a carbon cloth substrate using the galvanostatic method. The poly(s-triazine-co-o-aminophenol) (PT-co-oAP) is characterized, and its charge storage properties are investigated in 1 M H₂SO₄ and in 1 M ZnSO₄. At 1 A g⁻¹, the specific capacities of PT-co-oAP reach 101.3 mAh g⁻¹ and 84.4 mAh g⁻¹ in 1 M H₂SO₄ and in 1 M ZnSO₄, respectively. The specific capacity of PT-co-oAP maintains 90.3% of its initial value after cycling at 10 A g⁻¹ for 2000 cycles in 1 M H₂SO₄. The high specific capacity achieved originates from abundant surface active sites, facile ion diffusion, with optimized active site structure achieved by forming copolymer. The charge storage mechanism involves the redox processes of amino/imino groups and hydroxyl/carbonyl groups in the copolymer, together with the insertion of cations. Two electrode devices using two PT-co-oAP and aqueous 1 M H₂SO₄ are assembled, and the maximum energy density reaches 63 Wh kg⁻¹ at 0.5 A g⁻¹ with a power density of 540 W kg⁻¹. The capacity retention of the device after 3000 cycles at 10 A g⁻¹ reaches 81.2%. Full article

In the development of flexible smart electronics, fabricating electrodes with optimized architectures to achieve superior electrochemical performance remains a significant challenge. This study presents a two-step synthesis and characterization of a polypyrrole (PPy)-MnO₂/carbon cloth (CC) nanocomposite. The MnO₂/CC substrate was first prepared via the hydrothermal method, followed by uniform PPy coating through vapor-phase polymerization in the presence of an oxidizing agent. Electrochemical measurements revealed substantial enhancement in performance, with the specific capacitance increasing from 123.1 mF/cm² for the MnO₂/CC composite to 324.5 mF/cm² for the PPy/MnO₂/CC composite at a current density of 2.5 mA/cm². This remarkable improvement can be attributed to the synergistic effects between the conductive PPy polymer and MnO₂/CC substrate and the formation of additional ion transport channels facilitated by the PPy coating. This work provides valuable insights for designing high-performance electrode materials and advances the development of composite-based energy storage devices. Full article

The design parameters of large-scale iron-chromium redox flow batteries (ICRFB) encompass a wide range of internal and external operational conditions, including electrodes, membranes, flow rate, and temperature, among others. Among these factors, the intrinsic structures of graphite felt (GF) and carbon cloth (CC) play a pivotal role in determining the overall working conditions of ICRFBs. This study systematically investigates the multifaceted relationship between the intrinsic structure of the GF and CC and their impact on the operational performance of ICRFBs. The fundamental difference between the two types of electrodes lies in the intrinsic structure space available in them for electrolyte penetration. A systematic analysis of the structure–activity relation between the electrodes and the initial internal resistance, as well as the operating temperature of the cell, was performed. Additionally, the influence of the electrode structure on critical parameters, including the flow rate, membrane selection (Nafion 212 and Nafion 115), and performance of electrodeposition catalysts (bismuth and indium), is examined in detail. Under varying operating conditions, the intrinsic structures of GF and CC turn out to be a crucial factor, providing a robust basis for electrode selection and performance optimization in large-scale ICRFB systems. Full article

Flexible supercapacitors have emerged as pivotal energy storage components in wearable smart electronic systems, owing to their exceptional electrochemical performance. However, the widespread application of flexible supercapacitors in smart electronic devices is significantly hindered by the developmental bottleneck of high-performance anode materials. In this study, a novel electrode composed of surface-modified Fe₂O₃ nanoneedles uniformly coated with a polypyrrole (PPy) film and anchored on Co-MOF-derived N-C nanoflake arrays (PPy/Fe₂O₃/N-C) is designed. This composite electrode, grown in situ on carbon cloth (CC), demonstrated outstanding specific capacity, rate performance, and mechanical flexibility, attributed to its unique hierarchical 3D arrayed structure and the protective PPy layer. The fabricated PPy/Fe₂O₃/N-C@CC (P-FONC) composite electrode exhibited an excellent specific capacitance of 356.6 mF cm⁻² (143 F g⁻¹) at a current density of 2 mA cm⁻². The current density increased to 20 mA cm⁻², and the composite electrode material preserved a specific capacitance of 278 mF cm⁻² (112 F g⁻¹). Furthermore, the assembled quasi-solid-state Mn/Fe asymmetric supercapacitor, configured with P-FONC as the negative electrode and MnO₂/N-C@CC as the positive electrode, demonstrated robust chemical stability and notable mechanical flexibility. This study sheds fresh light on the creation of three-dimensional composite electrode materials for highly efficient, flexible energy storage systems. Full article

Considering the various morphologies of carbon nanotubes (CNTs), it is expected to solve the contradiction between concentration polarization and electrochemical polarization in vanadium redox flow batteries (VRFBs). This paper investigates the structural evolution of CNTs grown on the surface of thermally oxidized carbon cloth (TCC) and their impact on the performance of VRFBs. The morphological results indicate that thermal oxidation treatment forms pores on the surface of the TCC, providing nucleation sites for CNT growth. Spiral-shaped CNTs (TCC@s-CNTs) were formed in a short growth time (1 h), and their high defect density originated from the non-steady-state supply of carbon sources and the dynamic behavior of the catalyst. While 3 h of growth forms a network structure (TCC@n-CNT), the van der Waals force drives the self-assembly of its three-dimensional network. Although the TCC@s-CNT exhibits high catalytic activity due to its high defect density and edge active sites, the performance of VRFBs is more dependent on the three-dimensional conductive network of the TCC@n-CNT. At 240 mA/cm², the energy efficiency (EE) of a VRFB assembled with the TCC@n-CNT reaches 71%, and the capacity retention rate is 15% higher than that of the TCC@s-CNT. This work reveals the synergistic mechanism of CNT morphology regulation on electrode performance and provides theoretical guidance for the design of VRFB electrodes. Full article

Zirconium sulfide nanoparticles (Zr_xS_y) are prepared on a flexible substrate of carbon cloth (CC) via a one-step synthesis approach using the low-pressure chemical vapor deposition (LPCVD) technique. The scanning electron microscopy (SEM) image reveals that the particle sizes are in the range of ca. 3~23 nm with an average value of ~13.02 nm. The synthesized Zr_xS_y nanoparticles are composed of ZrS₃ and Zr₉S₂ phases, which is verified by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). By using the Zr_xS_y/CC as a supercapacitor flexible electrode, the capacitance extracted from the cyclic voltammetry measurement is 406 C g⁻¹ at a scan rate of 5 mV s⁻¹; the capacitance values obtained from GCD curves at a current density of 0.5 A g⁻¹ and 1 A g⁻¹ are 151 and 134 C g⁻¹, respectively. These results highlight the promising potential of Zr_xS_y as a supercapacitor material for future energy-storage technology. Full article

A priority area for low-cost LIBs is the commercial production of electrodes with a high cycle life and efficiency in an environmentally benign fashion and a cost-effective manner. We demonstrate the use of undoped/untreated, flexible, stand-alone, mesh-like carbon cloth (C-felt) as a potential alternative anode to commonly used graphite composite anodes (GRAs) in LIBs. The performances of commercial GRAs (9 m²/g) and C-felt (102 m²/g) were compared as anodes vs. LiFePO₄ (14.5 m²/g) cathodes in the full battery. Half-cell test results determined appropriate mass ratios of 2:1 for GRAs (LiFePO₄/GRA) and 1:1 for C-felt (LiFePO₄/C-felt). At a 0.3 C discharge rate, the 1:1 ratio yielded a specific discharge capacity of 104 mAh/g, in contrast to 87 mAh/g for the 2:1 ratio for a full cell in the 100th cycle, corresponding to a retention of 82% for the 1:1 LiFePO₄/C-felt full cell and 70% for the 2:1 LiFePO₄/GRA full cell from their first specific discharge capacities. By varying the ratio of C-felt anode to LiFePO₄ cathode in a full cell and expressing the specific capacity in the 100th cycle as a function of the fraction of C-felt present (at a fixed amount of LiFePO₄), a maximum specific capacity was achieved at a fraction of C-felt equal to 0.542 or (1:1.18) LiFePO₄/C-felt or 106 mAh/g. This corresponds closely to the experimentally determined value and supports (1:1) LiFePO₄/C-felt full cell as an optimum ratio that can outperform the (2:1) LiFePO₄/GRA full cell in our test conditions. Hence, we present C-felt anode as a potential cost-effective, lightweight anode material for low-cost LIBs. Full article

Electrochromic fabrics (ECFs) can be applied to wearable displays and military camouflage clothing, and they have great potential in developing wearable products. Current ECFs are often bulky, involve complicated processes, and have high production costs. In this study, we report a novel strategy for preparing electrochromic fabrics that require only a three-layer structure: cotton fabric as the substrate, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the electrochromic layer and the electrodes, and an ion-conducting film (ICF) bonded to the fabric by hot pressing. Compared with conventional ECFs, this method does not require the extra preparation of electrode layers on the fabric, as these layers affect the color-changing effect. Hot pressing eliminates the need for a complex sealing process and is more suitable for fabrics with poor wicking effects, which increases the method’s applicability. Cotton fabrics offer the value of biodegradability and are more environmentally friendly. Meanwhile, unlike carbon cloth, the fabric’s color does not interfere with the electrochromic effect. The ICF is non-liquid and can maintain the dryness of the fabric. Additionally, the ICF provides high-temperature protection up to 150 °C. The ECFs exhibit exceptional thinness at 161 µm and a lightweight construction with a 0.03 g/cm² weight. Furthermore, the ECFs exhibit a relatively long sustain time of 115 min without voltage, demonstrating impressive performance. Improved peel strength to 7.11 N is achieved through an improved hot-pressing process. The development strategy for ECFs can also be applied to other electrochromic substances, potentially advancing intelligent applications such as wearable fabrics and military camouflage while promoting rapid progress in electrochromic fabrics. Full article

Transition metal oxides (e.g., MnO_x) can effectively promote the redox reactions of heavy metal ions through abundant valence changes. However, relatively few studies have been conducted on the application of MnO_x for the detection of Cd²⁺ without pre-enrichment conditions. For this reason, in this study, MnO_x was grown in situ on a carbon cloth substrate by one-step electrodeposition. The effect of the valence composition of MnO_x and its variation on the Cd²⁺ without pre-enrichment detection performance was systematically investigated. The morphology, structure, and chemical composition of the materials were fully characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that the deposition of MnO_x not only significantly increased the active surface area of the electrodes but also facilitated electron transfer through the valence transition of Mn²⁺/Mn³⁺↔Mn³⁺/Mn⁴⁺. The detection of Cd²⁺ in water samples can be successfully achieved without pre-enrichment, and the electrode has good stability and reproducibility. This study provides a new design idea for applying MnO_x electrodes in Cd²⁺ detection without pre-enrichment and provides a reference for further optimization of electrochemical sensors. Full article

Although the detection of phosphate can be achieved by nickel hydroxide instead of noble metals, the sensitive detection of phosphate using nickel hydroxide transformed into hydroxy nickel oxide needs to be done under alkaline conditions, which is not environmentally friendly. To solve this problem, we prepared flake-shaped nickel hydroxide-sensitive electrodes supported on carbon cloth using a low-consumption one-step method from the new strategy that the specific adsorption of nickel hydroxide to phosphate can change the electrode’s surface charge distribution and investigated their performance in detecting phosphate under neutral conditions. The specific adsorption of phosphate changed the charge distribution on the surface of the electrode, improved the electron transfer efficiency, and facilitated the valorization of nickel, while the flake-shaped nickel hydroxide provided more active sites for the electrode, which resulted in a good performance of the nickel hydroxide electrode: a sensitivity of 1530 mA mM⁻¹ cm⁻², a detection range of 1–200 μM, and the LOD of 0.59 μM (S/N = 3). This work provides an innovative idea for the determination of phosphate under neutral conditions, which has important practical applications. Full article

The NiCo₂O₄ Nanosheets@Carbon fibers composites have been successfully synthesized by a facile co-electrodeposition process. The mesoporous NiCo₂O₄ nanosheets aligned vertically on the surface of carbon fibers and crosslinked with each other, producing loosely porous nanostructures. These hybrid composite electrodes exhibit high specific capacitance in a three-electrode cell. The asymmetric supercapacitor (NiCo₂O₄ Nanosheets@Carbon fibers//Graphene oxide) displayed a high specific capacitance of 91 F g⁻¹ and excellent cycling stability with a capacitance retention of 94.5% at 5 A g⁻¹ after 10,000 cycles. The device also achieved a notable energy density of 52 Wh kg⁻¹ coupled with a power density of 3.5 kW kg⁻¹ and a high power density of 7.1 kW kg⁻¹ with an energy density of 21 Wh kg⁻¹. This study shed light on the great potential of this asymmetric device as future supercapacitor. Full article

In our investigation, we unveil a novel, eco-friendly, and cost-effective method for crafting a bio-derived electrode using discarded cotton fabric via a carbonization procedure, marking its inaugural application in a vanadium redox flow battery (VRFB). Our findings showcase the superior reaction surface area, heightened carbon content, and enhanced catalytic prowess for vanadium reactions exhibited by this carbonized waste cloth (CWC) electrode compared to commercially treated graphite felt (TT-GF). Therefore, the VRFB system equipped with these custom electrodes surpasses its treated graphite felt counterpart (61% at an equivalent current) and achieves an impressive voltage efficiency of 70% at a current density of 100 mA cm⁻². Notably, energy efficiency sees a notable uptick from 58% to 67% under the same current density conditions. These compelling outcomes underscore the immense potential of the carbonized waste cotton cloth electrode for widespread integration in VRFB installations at scale. Full article

Designing novel π-conjugated conductive polymers with abundant redox-active groups is a viable route to achieve high charge storage performance for aqueous energy storage devices. Electropolymerization is a powerful tool to construct conductive polymers. Here, s-triazine is, for the first time, electropolymerized in an aqueous acidic solution on carbon cloth. The polytriazine-coated carbon cloth electrode (PT/CC) exhibits a granular structure, with abundant pores. The charge storage performance is investigated, and a specific capacity of 101.4 mAh ${\mathrm{g}}^{-1}$ at 1 A ${\mathrm{g}}^{-1}$ in 1 M ${\mathrm{H}}_2{\mathrm{S}\mathrm{O}}_4$ is achieved. Additionally, in 1 M ZnSO₄, a specific capacity of 50.3 mAh ${\mathrm{g}}^{-1}$ at 1 A ${\mathrm{g}}^{-1}$ can be achieved by the PT/CC. The PT/CC behaves as a battery-type charge storage electrode, and the amino/imino and carbonyl/hydroxyl groups contribute to the charge storage, with cation insertion and extraction. A symmetric aqueous charge storage device assembled with two PT/CC electrodes exhibits an energy density of 12.92 Wh ${\mathrm{k}\mathrm{g}}^{-1}$ and a power density of 250 W ${\mathrm{k}\mathrm{g}}^{-1}$ at 1 A ${\mathrm{g}}^{-1}$. After 2500 cycles at 10 A ${\mathrm{g}}^{-1}$, the device retains a specific capacity of 83.3%. This study indicates that the PT is a potential candidate material for an aqueous energy storage device. Full article