Journal of Solid State Electrochemistry最新文献

High-energy global requirements have caused a renewed interest in studying and developing new and improved energy storage devices and, precisely, the electrode materials that compose them, which play a fundamental role in determining the device’s performance. Carbon materials are first-class candidates due to their high electrical conductivity, chemical stability, and surface area. Although several carbon materials and their precursors have been studied, melamine sponges stand out for their nitrogen content, allowing them to act as a template and precursor for N-doped, ultralight carbon materials with good mechanical properties and a controlled pore size distribution. This work reports a simple and quick methodology to form ultralight and flexible carbon foam, along with the influence of the pyrolysis temperature on the physicochemical and electrochemical properties of 3D carbonaceous substrates used for energy storage and synthesized from melamine sponges. The substrates exhibit higher 3D porous structure than previously reported materials, with an average pore diameter of 80–90 µm. This morphology, added to the N content, promotes the remarkable electrochemical behavior (MS–950 °C) and cycling stability (MS–1000 °C) of almost 100% of capacitance retention after 10,000 cycles (≈ 60 F/g @1 A/g).

Rapid development of electronic and grid storage technologies based on lithium-ion batteries are leading to tight supply of lithium resources in the future. Extracting lithium from seawater can completely solve the problem of lithium resource shortage. An electro-deposition method based on a lithium superionic conductive solid-state electrolyte, Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP), has been reported to obtain metallic lithium from seawater. However, expensive LAGP increases the cost of lithium extraction, while Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) with relatively lower prices cannot meet the stable requirements. Herein, a low-cost, stable glass–ceramics, Li_1.5Al_0.3Ti_1.7Si_0.2P_2.8O₁₂ (LATSP), has been prepared for lithium extraction from seawater. The LATSP glass–ceramics show good selectivity towards Li⁺ and exhibit a high ionic conductivity of 3.98 × 10⁻⁴ S cm⁻¹ at 22 °C. After soaking in simulated seawater, LATSP showed much better stability than LATP, comparable to LAGP. The resultant LATSP glass–ceramics was successfully employed in a seawater lithium extraction device, with a high lithium extraction Coulombic efficiency of 94.0%. Moreover, the LATSP exhibits an ionic conductivity of 2.80 × 10⁻⁴ S cm⁻¹ and maintains a complete structure after 45 h of lithium extraction. This work presents an effective and practical Li-ion conducting membrane for lithium extraction from seawater.

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The supercapacitive properties of the polythiophene (PTh) and its composites with iron dust synthesized by chemical oxidative polymerization are investigated. The UV–Vis, FTIR, TGA, XRD, SEM, and EDX were used to characterize the composites. Iron (Fe) dust is inserted into PTh matrix as confirmed by FTIR, UV–Vis, EDX, and XRD analysis. The TGA shows that composites have higher thermal stability than pure PTh. The SEM reveals highly porous and packed morphology of the composites as compared to pure PTh. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) show that a 1:1 ratio by mass of PTh and Fe composite displayed greater specific capacitance than pure PTh. The high specific capacitance of the composite material (428.46 F/g at 1 A/g) suggested that the material is suitable for supercapacitor electrode. Cyclic stability is also tested for 1000 cycles at a current density of 1 A/g with excellent retention of 88.89%.

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Iron-based Prussian blue analogs (PBAs) are synthesized using a modified coprecipitation approach at different temperatures to study the effect of coprecipitation reaction temperature on structural and electrochemical performance. The experimental results showed that the iron-based PBAs transferred from the cubic structure to the monoclinic phase as the temperature increased from 5 °C to 60 °C, with the former exhibiting rich-in-boundary morphology and the latter showing a well-defined cubic shape. The electrochemical performance of the samples is closely related to the structure: the PBAs with monoclinic structures exhibit a higher charge/discharge specific capacity than those of PBAs with cubic structures. In addition, the samples are further treated at 270 °C, new phases are probed, and the charge/discharge specific capacity for the HT-PB-60 sample is significantly improved by more than 36.15%.

Passivity breakdown mechanism of high-strength 7068 alloy is studied. Breakdown potential varied linearly with log a_Cl^‒, pH, and square root of scan rate in potentiodynamic polarization tests. Mott-Schottky analysis showed that the dominant defect is cation vacancy. Passive layer characteristics like cation vacancy density and defect annihilation rate are determined. Critical cation vacancy density for pitting obtained from point defect model and the theoretical values are somewhat compatible. Chloride concentration of 0.01 M is too dilute to cause severe localized corrosion, whereas beyond 0.5 M, saturation is achieved in terms of breakdown potential and the cation vacancy density.

When graphene oxide (GO) was reduced, the stacking of reduced graphene oxide (rGO) sheets would lead to far lower of its specific capacitance than the theoretical value of graphene. In order to solve this problem, we use tannic acid (TA) to modify the rGO layered film by vacuum filtration of the mixture of GO and TA in solution, and then mild thermal reduction at 180℃. Due to the rich redox active functional groups of TA, the introduction of TA can not only alleviate the stacking of rGO sheets and promote the reduction process of GO at relatively low temperature, but also provide additional pseudocapacitance. When used for two-electrode symmetrical supercapacitor in 6 M KOH electrolyte, the TrGO-0.5 gives areal capacitance of 525 mF cm⁻², and energy density of 72.2 uWh cm⁻² at power density of 250.9 uW cm⁻². It also has capacitance retention of 91.7% after 10,000 charging/discharging cycles at current density of 4 mA cm⁻². The TrGO-0.5 based button cell with 2 M 1-ethyl-3-methylimidazole tetrafluoroborate (EMIMBF₄) as electrolyte shows the practical application to light up three LEDs.

A new integrated electrode-separator-electrolyte hydrogel is designed and prepared, which is composed of organic liquid crystal, polyvinyl alcohol (PVA), polyaniline (PANI), and reduced graphene oxide (rGO). The organic liquid crystal is introduced into PVA hydrogel, effectively improving compatibility between active materials and hydrogel matrix. The PANI active material is in situ polymerized in hydrogel to prepare PANI-double-network hydrogel. It simultaneously acts as electrode, separator, and electrolyte for assembling flexible solid-state supercapacitor. It obtains an area-specific capacitance of 160.2 mF/cm² and a power density of 101.5 μW/cm² with an energy density of 21.0 μWh/cm². This work provides a new method to reduce interfacial resistance of electrode, separator, and electrolyte of flexible solid-state supercapacitor, further improving its electrochemical performance.