Solid State Ionics最新文献

Practical application of lithium‑sulfur batteries (LSBs) is severely impeded by the poor conductivity of sulfur/Li₂S, large-volume change of active materials, shuttle effect and sluggish conversion reaction kinetics of polysulfides. To address these issues, a three-dimensional (3D) substrate, which was prepared by anchoring CoO nanoarrays on the surface of nickel foam (NF@CoO) through one-step hydrothermal treatment, is used as the current collector of the sulfur cathode. The as-prepared S/NF@CoO cathode presents excellent electrochemical performances due to the high electronic conductivity of nickel network, chemical adsorption and catalysis of CoO nanoarrays to LiPSs, and highly porous structure of nickel foam. The cathode with a sulfur loading of 2.72 mg cm⁻² can deliver an initial capacity of 490 mAh g⁻¹ at 1C, and 306 mAh g⁻¹ after 500 cycles. When the sulfur loading is increased to 5.12 mg cm⁻², the resultant cathode can achieve a capacity of 2.3 mAh cm⁻² at 0.5C. The results demonstrate that the 3D NF@CoO collector with synergistic effects of catalysis and chemisorption on LiPSs enable the sulfur cathode thick with meeting the requirements of practical use of LSBs.

Metallic Sn is considered as a promising candidate of anode materials for lithium-ion batteries (LIBs) owing to its high capacity and ease of preparation. However, it undergoes severe mechanical damage after several lithiation/delithiation cycles due to the large volume change (∼300%). In this study, ultrafine Sn nanograins are embedded in N-doped amorphous carbon and then anchored onto reduced graphene oxide (rGO) via a facile one-pot synthesis route. The resulting composite consists of highly active Sn nanograins, three-dimensional carbon frameworks and highly conductive graphene oxide matrices. This unique configuration endows the composite with promising electrochemical performance. It delivers a reversible capacity of 1392 mAh g⁻¹ at a current density of 50 mA g⁻¹. When cycled after 300 times at 500 mA g⁻¹, it still maintains a reversible capacity of 805 mAh g⁻¹.

In this work, Mn₂O₃/Mn₃O₄ composites are prepared by a facile sucrose-assisted thermal decomposition method using MnCl₂·4H₂O, Mn(CH₃COO)₂·4H₂O, and MnSO₄·H₂O as manganese sources, respectively. The results demonstrate that manganese salt type has a significant influence on the morphology and phase composition of the final Mn₂O₃/Mn₃O₄ composites. The composites prepared from MnCl₂·4H₂O or Mn(CH₃COO)₂·4H₂O possess a porous sheet-like morphology, while the Mn₂O₃/Mn₃O₄ composite prepared from MnSO₄·H₂O has a much finer nanosheet morphology. The Mn₂O₃ contents in the composites prepared from MnCl₂·4H₂O, Mn(CH₃COO)₂·4H₂O, and MnSO₄·H₂O are about 57.8%, 95.0%, and 27.0%, respectively. Due to the differences in morphology and phase composition, the Mn₂O₃/Mn₃O₄ composites prepared from MnCl₂·4H₂O and Mn(CH₃COO)₂·4H₂O exhibit better zinc storage properties than the composite prepared from MnSO₄·H₂O. Among the three samples, the Mn₂O₃/Mn₃O₄ composite prepared from Mn(CH₃COO)₂·4H₂O shows superior zinc storage capability in short-term cycling and the best rate capability; the Mn₂O₃/Mn₃O₄ composite prepared from MnCl₂·4H₂O presents the best long-term cycling performance and moderate rate capability; the Mn₂O₃/Mn₃O₄ composite prepared from MnSO₄·H₂O displays the worst zinc storage capability and rate performance. EIS and CV analysis demonstrate that the Mn₂O₃/Mn₃O₄ composites prepared from MnCl₂·4H₂O or Mn(CH₃COO)₂·4H₂O have a low charge transfer resistance and obvious pseudocapacitive behavior during the charge/discharge process. The charge/discharge mechanism of the Mn₂O₃/Mn₃O₄ composites is also explored by ex-situ XRD characterization. This work provides a reference for the simple preparation of high-performance Mn₂O₃/Mn₃O₄ composites utilizing different manganese salts.

Solid oxide electrolysis cell (SOEC) is an efficient and environmentally friendly energy conversion device. The commercialization of SOEC is limited by the oxygen electrodes, whose problems include high costs and unexpected degradation of cobalt/strontium. In this study, we proposed a co-doping strategy and synthesized cobalt-free and strontium-free perovskite materials, specifically Ba_0.95Gd_0.05Fe_1-xCu_xO_3-δ (BGFCu_x), via the sol-gel method. These materials were evaluated as potential air electrodes for SOEC. The BGFCu_x samples were systematically characterized by crystal structure, oxygen content, thermal properties, electrical conductivity, and electrochemical performance. X-ray diffraction results show that the solid-solution concentration of Cu in BGFCu_x cannot exceed 0.1. X-ray photoelectron spectroscopy results suggest that Cu doping increases oxygen vacancy concentration. Among all BGFCu_x perovskites, BGFCu0.1 exhibited a low polarization resistance of 0.069 Ω·cm² at 800 °C (0.2 V) and a high current density of 216 mA·cm⁻² at an anodic bias of 40 mV. Hence, the Gd and Cu co-doped BGFCu0.1 perovskite material is a promising air electrode for SOEC.

Oxygen atom migration within solid oxides exerts a profound affects material properties, yet a rigorous conceptual framework for quantifying dynamic migration has been absent. To bridge this gap, we have developed a dynamic oxygen migration-release model, employing the differential element method with comprehensive mathematical proof. This novel model elucidates the exponential decay in the oxygen release rate of metal oxides as a function of the liberated oxygen quantity. We refined the model to discern between the migration of interior (bulk) oxygen and the reactions of oxygen at the surface, providing experimental validation for the energy barriers associated with each migration process. Taking CeO₂ as a case study, our model predicted and corroborated the energy barrier for oxygen release under various temperatures and morphologies, aligning with Density Functional Theory (DFT) analysis. Furthermore, the model's versatility is evidenced by its applicability to a wide range of metal oxides, including ceria-zirconia solid solutions, manganese oxide, and iron oxide, suggesting a broad potential for universal application. The unveiled dynamics of oxygen migration and release provide a theoretical foundation for refining the design of functional metal oxides and lay the groundwork for a more precise assessment of their oxygen reactivity.

In the present study, the electrochemical performance of the nickel (Ni)-foam electrodes (nano-confined-metal oxide composites: nc-SiO₂, nc-Al₂O₃, nc-MgO, nc-CaO) coated by electrodeposition via nano-confined lithium borohydride (nc-LiBH₄)-metal oxide (SiO₂, Al₂O₃, MgO, CaO) composites were investigated. Nano-confinement of LiBH₄ on metal-oxide structure approach was applied by a ball-milling process to prepare composites. The nc-metal oxide composites were electrodeposited on Ni foam using the chronoamperometry (CA) technique. The comparative study by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods at different scan rates and current densities were used for electrochemical characterization of nc-metal oxide composites towards neat LiBH₄ and metal oxide. Cross-sectional analyses of scanning electron microscope elucidated that nc-CaO composite uniformly blankets the inner and outer surfaces of foam. These composites showed superior stability and reduced porosity in their surface structures, predominantly characterized by granular morphology and weak interparticle bonding, in contrast to other composite materials. Among CV curves, nc-CaO electrodeposited Ni foam electrode displayed a reduction of charge storage and lower capacitance values due to reduced porosity of nc-CaO composite towards LiBH₄ advanced in nano-confinement approach. Comparing specific capacitance of the electrodes first increased up to around 130 F/g and then decreased when metal oxides were added, while Ni electrodes prepared without nc-metal oxide composites showed an inverse relation with increasing current. The highest capacitance retention still after 2000 cycles achieved 85% stability.

Micro-contact impedance spectroscopy (mcIS) is a powerful tool that can allow local features such as grain boundaries and surfaces in electro-ceramics to be directly interrogated. Typical macroscopic electrodes fully cover the specimen surfaces and data are converted from resistance into conductivity using a geometric correction factor based on the surface area of the electrodes and thickness of the sample. For mcIS measurements this requires a different approach. The conversion factor required in this case is that for a spreading resistance and the correction factor depends on the radius (r) and separation of the micro-contacts. When dealing with conversions for samples with a resistive surface layer, two extreme scenarios exist depending on the thickness of the surface layer (T) and the arrangement and size of the contacts. When the resistive layer is thin (T/r < 10) the geometric correction factor provides accurate conductivities but for thick layers (T/r > 10) the spreading resistance correction equation is required. When the surface layer is an intermediate thickness however neither provides a good estimate for conductivity.

Using finite element modelling we simulate resistive surface layer systems using a top-top micro-contact arrangement and show that instead of using either of the two separate correction equations, a single modified spreading resistance equation can be used on the resulting impedance data to provide greater accuracy and simplicity in the extraction of conductivity. With this modified correction factor, when the ratio of bulk material conductivity versus surface layer conductivity (σ_b/σ_s) is ≥100, σ_s can be calculated for any surface layer thickness. When the ratio is <100, only when (T/r) is >3 can σ_s be accurately estimated.

This study investigates the enhancement of electrochemical performance in alginate–polyvinyl alcohol (PVA) solid blend electrolytes through H⁺ ion doping for supercapacitor applications. Employing the solution casting method, we tailored electrolyte systems doped with nitric acid (HNO₃). Impedance studies reveal a substantial increase in ionic conductivity (2.71 × 10⁻⁴ S cm⁻¹ at room temperature) with 3 M HNO₃ doping. Fourier-transform infrared spectroscopy and transference number measurements confirm the effective protonation of the polymer matrix. Temperature-dependent behavior analysis demonstrates robust performance across various thermal conditions. Linear sweep voltammetry studies showcase excellent electrochemical stability, while galvanostatic charge-discharge profiles exhibit reliable cyclic performance, with an average specific capacitance of approximately 6.76 F/g. This research underscores the potential of tailored solid blend electrolytes doped with H⁺ ions to elevate supercapacitor technology.

Iron has proven to be a simple yet high-performing electrode for ammonia electrosynthesis, particularly when used with protonic ceramic electrolysis cells. On a proton-conducting BaCe_0.9Y_0.1O_3−δ (BCY) electrolyte, iron oxide forms an interfacial layer during sintering due to solid-state cation diffusion. In this work, we found that the ceria‑iron layer that is formed in-situ both enables electrode adhesion and is active for ammonia electrosynthesis. Cells with electrodes fabricated from CeO₂-Fe₂O₃ at a weight ratio of 1:1 (CeFe11) and 6:1 (CeFe61), designed to replicate the composition of the interfacial layer, resulted in ammonia formation rates similar to those of cells with pure Fe electrodes, reaching 1.1–1.2 × 10⁻⁸ mol s⁻¹ cm⁻² at an applied voltage of −1 V at 600 °C. The ceria‑iron catalysts exhibited higher catalytic activity and a moderate electrochemical activity. A comparison of these electrodes suggests that the regions where ceria and iron are in proximity are the most active for ammonia electrosynthesis. Furthermore, CeFe11 demonstrates similar ammonia formation rates on BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (BZCYYb1711) as on BCY; as BZCYYb is more stable than BCY in the presence of water vapor, the development of ceria‑iron electrodes could widen the application of iron-based electrodes to ammonia electrosynthesis combined with water electrolysis.