Ionics最新文献

Spinel LiMn₂O₄ has been regarded as one of the most promising cathode materials due to its low cost, environmental friendliness, high thermal stability and safety. However, the issues such as manganese dissolution and Jahn–Teller effect result in significant capacity degradation during long high-temperature cycling, limiting its large-scale application. In this study, we develop a novel metal manganese corrosion-oxidation method to fabricate high-purity spherical Mn₃O₄, which is then employed as the superior manganese source for the synthesis of spinel LiMn₂O₄ via high-temperature solid-state process. Moreover, the effects of different lithium sources and mole ratios of lithium to manganese on the structure and electrochemical performance of LiMn₂O₄ are investigated. It was found that the obtained LiMn₂O₄ exhibits excellent electrochemical performance by using lithium carbonate as the lithium source with a lithium to manganese ratio of 0.53. The discharge capacities at 1 C and 10 C are 124.9 and 106.0 mAh/g, respectively, and the capacity retention after 200 cycles at 1 C is 93.7%. These excellent properties are attributed to the high-purity and spherical morphology of the Mn₃O₄ precursor, which dramatically improves the structural stability and electrochemical kinetics of LiMn₂O₄. This work provides a straightforward and cost-effective pathway for the large-scale industrial production of high-performance spinel LiMn₂O₄ cathode materials for lithium-ion batteries.

The detection of lead ions (Pb(II)) in environmental samples is crucial due to their significant toxicity and ability for triggering serious health and ecological harm, even at minimal concentrations. The Co₃O₄/RGO nanocomposite was used for modification of glassy carbon electrodes (GCE) for sensitive electrochemical detection of trace lead ions (Pb(II)) in environmental samples. This study generated cobalt oxide nanoparticles (Co₃O₄ NPs) by an effective precipitation process and functionalized them with reduced graphene oxide (RGO) to form a nanocomposite. The resultant materials were thoroughly characterized utilizing techniques such as powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The redesigned electrode showed remarkable electrochemical performance as measured by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV). The sensor had a linear response to Pb(II) concentrations ranging from 10 to 90 ppb, with a detection limit of 0.5 ppb estimated using the 3σ method. This novel sensor offers a promising platform for environmental monitoring of harmful heavy metals.

It is critical to accurately predict the capacity and remaining useful life (RUL) of lithium-ion batteries (LIBs) for reliable operation and timely maintenance of electric vehicles. However, challenges persist due to the uncertainty in battery capacity degradation trends and interference from external noise. This study suggests a novel neural network model, DPformer, to capture the capacity fade trend and reduce interference from external noise, which integrates feature reconstruction, attention mechanism, and combined multi-layer perception. Firstly, the raw data is reconstructed and denoised by an automatic denoising encoder (ADE), and the long-term dependencies in time series information are effectively captured via the attention mechanism. Subsequently, the extracted multi-scale information is further processed by a designed feature pyramid decoder (FPD) to achieve better feather representations. In addition, a particle swarm optimization algorithm is improved to optimize the hyperparameters of the proposed model more precisely. Finally, the performance of the proposed is validated by using two public datasets. Experimental results demonstrate that the model achieves good performances in prediction accuracy and generalizability, and achieves up to 30–50% improvement in terms of relative error (RE).

The potential of Sc-Si₅₂, Sc-C₅₂ and Sc-Al₂₆P₂₆ to catalyze the ORR pathways has been investigated. The possible mechanisms and corresponding parameters for reaction steps of ORR on Sc-Si₅₂, Sc-C₅₂ and Sc-Al₂₆P₂₆ have been investigated. The adsorption of Scandium atoms on Si₅₂, C₅₂ and Al₂₆P₂₆ nanocages can be improved the stability of Sc-Si₅₂, Sc-C₅₂ and Sc-Al₂₆P₂₆ nanocages, significantly. The adsorption energy (E_adsorption) of Scandium atoms on Si₅₂, C₅₂ and Al₂₆P₂₆ nanocages to create the Sc-Si₅₂, Sc-C₅₂ and Sc-Al₂₆P₂₆ are -4.13, -4.25 and -4.52 eV, respectively. The Sc atoms of Sc-Si₅₂, Sc-C₅₂ and Sc-Al₂₆P₂₆ are active sites for adsorption of species as the first step of ORR on studied catalysts. The formation of *OH-OH* is the rate-determining step on surfaces of Sc-Si₅₂, Sc-C₅₂ and Sc-Al₂₆P₂₆. The Sc-Al₂₆P₂₆ for ORR pathways has lower over-potential than Sc-Si₅₂ and Sc-C₅₂. Finally, the Sc-Al₂₆P₂₆ nano-catalyst is suggested as available catalyst for ORR processes with low over-potential and high efficiency.

High-entropy perovskite oxides (HEPOs) have emerged as promising electrode materials for supercapacitors. In this study, we successfully synthesized a series of HEPOs La_1-xSr_x(Co_0.2Mn_0.2Fe_0.2Ni_0.2Cu_0.2)O₃, using the sol–gel method. We thoroughly investigated the impact of Sr doping on the electrochemical properties of HEPO materials. Our findings indicate that the incorporation of a small amount of Sr enhances ionic conductivity and promotes the formation of oxygen vacancies and ionic vacancies within the crystal structure. The incorporation of Sr significantly improves the electrochemical performance of HEPOs materials. La_0.9Sr_0.1(Co_0.2Mn_0.2Fe_0.2Ni_0.2Cu_0.2)O₃ electrode exhibits a maximum specific capacitance of 204.33 F/g at a scan rate of 2 mV/s, a significant increase compared to the undoped La(Co_0.2Mn_0.2Fe_0.2Ni_0.2Cu_0.2)O₃ sample. Furthermore, La_0.9Sr_0.1(Co_0.2Mn_0.2Fe_0.2Ni_0.2Cu_0.2)O₃ electrode exhibits excellent rate performance, maintaining 74% of its capacity when the current density was increased from 1 to 5 A/g. It also exhibits good cycling stability, with nearly no attenuation after 1000 cycles. Therefore, these results underscore the potential of our synthesized high-entropy perovskite oxides as electrode materials for supercapacitors applications.

The main distinguishing feature of protic ionic liquids (PILs) is that their cations have at least one accessible proton, which allows them to form hydrogen bonds with anions. Furthermore, their cost-effectiveness and straightforward synthesis technique make them suitable for large-scale applications. In the present work, a series of ammonium based protic ionic liquids (PILs) and aprotic ionic liquids (AILs), which are tris(2-hydroxyethyl)ammonium acetate ([HEA][Ac]), tris(2-hydroxyethyl)ammonium lactate ([HEA][La]), tris(2-hydroxyethyl)ammonium butyrate ([HEA][BU]), tris(2-hydroxyethyl)ammonium ascorbate ([HEA][AS]), allyl tris(2-hydroxyethyl)ammonium chloride ([AyHEA][Cl]), and benzyl tris(2-hydroxyethyl)ammonium chloride ([BzHEA][Cl]), were synthesized and characterized using nuclear magnetic resonance (NMR) spectroscopy, infrared spectroscopy (IR), and elemental analysis. The densities, viscosities, and refractive indices of these ILs were determined at temperatures ranging from 273.15 to 353.15 K. In addition, various thermodynamic properties, including the thermal expansion coefficient, molar refraction, standard molar entropy, and lattice energy, were estimated for these ILs. The results demonstrate that these ionic liquids (ILs) exhibit lower densities, comparable refractive indices and viscosities, and a lower decomposition temperature than their analogs based on tri-(2-hyroxyethyl) ammonium. In addition, the ILs exhibited a slight dependence on temperature for the thermal expansion coefficients, αp, which ranged from 6.27 × 10⁻⁴ to 7.07 × 10⁻⁴ K⁻¹. These findings offer valuable information on the properties and potential uses of tris(2-hydroxyethyl)ammonium-based protic and aprotic ionic liquids containing carboxylate and chloride anions.

The growing need for large-scale energy storage demands the creation of multifunctional electrode materials. This paper describes the production and manufacture of mixed-phase nickel sulfide composites containing rGO for use as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) and supercapacitor electrodes. XRD, SEM, XPS, and TEM were used to investigate the composites' structural, morphological, and optical features. The use of CEs in DSSC required the exploration of NiS/rGO composite CEs. The DSSC based on NiS/rGO20 attained a fill factor (FF) of 0.72 and a photoconversion efficiency of 7.95%, outperforming the pure NiS-based DSSC, which had an FF of 0.63 and a power conversion efficiency of 5.45%. In supercapacitor applications, the NiS/rGO20 electrode had a Cs of 801 F g⁻¹ at a scan rate of 5 mV s⁻¹, which was much higher than the pristine NiS electrode's capacitance of 545 F g⁻¹ under the same circumstances. In supercapacitor assessments, the NiS/rGO20 electrode displayed a specific capacitance of 1015 F g⁻¹ at a current density of 2 A g⁻¹, showing a 24% boost over the pure NiS electrode. The asymmetric supercapacitor containing NiS/rGO20 and activated carbon attained an energy density of 43.8 Wh kg⁻¹ at a power density of 1999 W kg⁻¹, with 91% capacitance retention after 5000 cycles. The results show that NiS/rGO20 is a very efficient material for converting and storing energy purposes.

In this work, NiO/Co₃O₄ nanocomposite for energy storage and conversion applications has been synthesized using the hydrothermal method. The structural, optical, and morphological characteristics were analysed using X-ray diffraction, photoluminescence spectroscopy, and scanning electron microscopy techniques. As-prepared NiO/Co₃O₄ nanocomposite electrode exhibited a diffusion-controlled charge storage behavior with a remarkable storage capacity of 958 F/g at a current density of 1 A/g in 1 M KOH electrolyte solution. In spite after 4000 cycles at a current density of 5 A/g, the NiO/Co₃O₄ electrode showed higher cycling stability about 75% of its specific capacitance retention. The symmetric device exhibited a specific capacitance of 31.7 F/g at 1 A/g current density and achieved an energy density of 4.5 Wh/kg at a power density of 966 W/kg. A particularly promising outcome of this study was the device’s excellent cyclic stability, retaining 63% of its capacity after 3000 discharge cycles at a current density of 5 A/g. In addition, the NiO/Co₃O₄ nanocomposite electrode, when employed as an oxygen evolution reaction (OER) catalyst, highlights an admirable OER activity with overpotential of 340 mV at 10 mA/cm² and a lower Tafel slope of 86 mV/decade. The stability tests also validate a tremendous performance of NiO/Co₃O₄ nanocomposite even after 10 h without obvious degradation.

This study investigates the electrochemical properties of zinc-based metal–organic framework MOF-74 (ZnMOF-74) as a potential anode material for lithium-ion batteries (LIBs). Commercial graphite anodes are limited by a low specific capacity of 372 mAh/g, prompting the search for alternative materials with higher energy density. ZnMOF-74 was synthesized via a co-precipitation method and characterized using XRD, FTIR, SEM, and thermal analysis, confirming its crystalline structure and porosity. Electrochemical measurements, including cyclic voltammetry and galvanostatic cycling, revealed an initial high capacity exceeding 800 mAh/g in the first discharge cycle. However, a significant capacity drop to 273 mAh/g occurred in the second cycle, stabilizing around 67 mAh/g after 170 cycles. This rapid decline is attributed to the irreversible degradation of the MOF-74 framework during initial cycling, leading to the formation of Zn–Li compounds. The study concludes that the zinc center in MOF-74 does not facilitate electron mobility via the extended π-systems of the organic linker, hindering reversible redox processes and causing structural breakdown. Compared to MOFs with other metal centers like cobalt, ZnMOF-74 shows limited electrochemical reversibility and stability. Therefore, while ZnMOF-74 exhibits initial high capacity, its practical application as an anode material is constrained by structural degradation.

In the present study, we report the synthesis of sodium-ion (Na⁺) conducting blended solid polymer electrolytes (PEO-PEMA) by the standard solution casting technique with SiO₂ filler. X-ray diffractometer (XRD) and Field emission scanning electron microscopy (FESEM) confirmed the complete salt dissociation and provided evidence of the composite formation. Furthermore, Fourier transform infrared spectroscopy (FTIR) supported the XRD analysis. Impedance spectroscopy (EIS), linear sweep Voltammetry (LSV), and i-t curve characteristics are used to investigate the electrical properties. The high conductivity value (~ 8×({10}^{-5}) S cm⁻¹ ) was obtainded for a 2% concentration of SiO₂ by wt. It also exhibited a high operating voltage range (4.3 V) and a high value of transference number (0.99), which makes it a potential candidate for energy storage devices. The degree of polarization and supports the high conductivity, suggesting that ion migration is mainly due to the segmental motion of the polymer chain. The shifting of loss tangent peaks toward the higher frequency window reflects the reduction of relaxation time. Loss tangent analysis confirmed this decrease in relaxation time with nanofiller addition. Furthermore, complex conductivity analysis showed a strong dependence on nanofiller content. The sigma representation (σ′′ versus σ′) validated the decrease in relaxation time, which agrees with the loss tangent analysis. Ion transport parameters (n, μ, D) were evaluated using the Bruce-Vincent (B-M) method, electrochemical impedance spectroscopy, and FTIR analysis. All the transport parameters showed good agreement with each other. Finally, an ion transport mechanism based on experimental findings was proposed to examine the possible interactions in the polymer nanocomposite matrix.