Search Results (615)

In this work, graphite anodes and lithium iron phosphate (LFP) cathodes are used to examine the effects of sodium hexafluorophosphate (NaPF₆) and potassium hexafluorophosphate (KPF₆) electrolyte additives on the formation of the solid electrolyte interphase and the performance of lithium-ion batteries in both half-cell and full-cell designs. The objective is to assess whether these additives may increase cycle performance, decrease irreversible capacity loss, and improve interfacial stability. Compared to the control electrolyte (1.22 M Lithium hexafluorophosphate (LiPF₆)), cells with NaPF₆ and KPF₆ additives produced less SEI products, which decreased irreversible capacity loss and enhanced initial coulombic efficiency. Following the formation of the solid electrolyte interphase, the specific capacity of the control cell was 607 mA·h/g, with 177 mA·h/g irreversible capacity loss. In contrast, irreversible capacity loss was reduced by 38.98% and 37.85% in cells containing KPF₆ and NaPF₆ additives, respectively. In full cell cycling, a considerable improvement in capacity retention was achieved by adding NaPF₆ and KPF₆. The electrolyte, including NaPF₆, maintained 67.39% greater capacity than the LiPF₆ baseline after 20 cycles, whereas the electrolyte with KPF₆ demonstrated a 30.43% improvement, indicating the positive impacts of these additions. X-ray photoelectron spectroscopy verified that sodium (Na⁺) and potassium (K⁺) ions were present in the SEI of samples containing NaPF₆ and KPF₆. While K⁺ did not intercalate in LFP, cyclic voltammetry confirmed that Na⁺ intercalated into LFP with negligible impact on the energy storage of full cells. These findings demonstrate that NaPF₆ and KPF₆ are suitable additions for enhancing lithium-ion battery performance in the popular artificial graphite/LFP system. Full article

Recently, we have described SrMo_1-xMg_xO_3-δ perovskites (x = 0.1, 0.2) as excellent anode materials for solid oxide fuel cells (SOFCs), with mixed ionic and electronic conduction (MIEC) properties. After depositing on the solid electrolyte, they were annealed for sintering at high temperatures (typically 1000 °C), giving rise to oxidized scheelite-type phases, with SrMo_1-xMg_xO_4-δ (x = 0.1, 0.2) stoichiometry. To obtain the active perovskite phases, they were reduced again in the working anode conditions, under H₂ atmosphere. Therefore, there must be an excellent reversibility between the oxidized Sr(Mo, Mg)O_4-δ scheelite and the reduced Sr(Mo, Mg)O_3-δ perovskite phases. This work describes the topotactical oxidation, by annealing at 400 °C in air, of the SrMo_0.9Mg_0.1O_3-δ perovskite oxide. The characterization by X-ray diffraction (XRD) and neutron powder diffraction (NPD) was carried out in order to determine the crystal structure features. The scheelite oxides are tetragonal, space group I4₁/a (No. 88), whereas the perovskites are cubic, s.g. Pm-3m (No. 221). The Rietveld refinement of the scheelite phase from NPD data after annealing the perovskite at 400 °C and cooling it down slowly to RT evidences the absence of intermediate phases between perovskite and scheelite oxides, as well as the presence of oxygen vacancies in both oxidized and reduced phases, essential for their performance as MIEC oxides. The topotactical relationship between both crystal structures is discussed. Full article

The increasing demand for high-performance energy storage devices has stimulated interest in advanced electrolyte materials. Among them, ionic liquids ($\mathrm{I}\mathrm{L}\mathrm{s}$) stand out for their thermal stability, wide electrochemical windows, and good ionic conductivity. When doped into polymeric matrices, these ionic liquids form hybrid polymeric electrolytes that synergize the benefits of both liquid and solid electrolytes. This study explores a polymeric electrolyte based on polyethylene oxide ($\mathrm{P}\mathrm{E}\mathrm{O}$) doped with tributylmethylphosphonium iodide $\left(\mathrm{T}\mathrm{M}\mathrm{P}\mathrm{I}\right)$ and ammonium iodide ($\mathrm{N}{\mathrm{H}}_4\mathrm{I}$), focusing on its synthesis, structural and electrical properties, and performance in energy storage devices such as dye-sensitized solar cells and supercapacitors. Strategies to improve its ionic conductivity, mechanical and chemical stability, and electrode compatibility are also discussed, along with future directions in this field. Full article

The solid electrolyte interphase (SEI) on the anode of lithium-ion batteries (LIBs) has been studied thoroughly due to its crucial importance to the battery’s long-term performance. At the same time, most studies of the SEI apply ex situ characterization methods, which may introduce artifacts or misinterpretations as they do not investigate the SEI in its unaltered state immersed in liquid battery electrolyte. Thus, in this work, we focus on using the non-destructive combination of electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) and impedance spectroscopy (EIS) in the same electrochemical cell. EQCM-D can not only probe the solidified products of the SEI but also allows for the monitoring of viscoelastic layers and viscosity changes of the electrolyte at the interphase during the SEI formation. EIS complements those results by providing electrochemical properties of the formed interphase. Our results highlight substantial differences in the physical and electrochemical properties between the SEI formed on copper and on amorphous carbon and show how formation parameters and the additive vinylene carbonate (VC) influence their growth. The EQCM-D results show consistently that much thicker SEIs are formed on carbon substrates in comparison to copper substrates. Full article

The growing demand for high-energy, safe, and sustainable lithium-ion batteries has increased interest in nickel-rich cathode materials and solid-state electrolytes. This study presents a scalable wet-processing method for fabricating composite cathodes for all-solid-state batteries. The cathodes studied herein are high-nickel LiNi_0.90Mn_0.05Co_0.05O₂, NMC955, the sulfide-based electrolyte Li₆PS₅Cl, and alternative binders—polyvinyl alcohol (PVA) and polyisobutylene (PIB)—dispersed in toluene, a non-polar solvent compatible with the electrolyte. After fabrication, the cathodes were characterized using SEM/EDX, sheet resistance, and Hall effect measurements. Electrochemical tests were additionally performed in all-solid-state battery half-cells comprising the synthesized cathodes, lithium metal anodes, and Li₆PS₅Cl as the separator and electrolyte. The results show that both PIB and PVA formulations yielded conductive cathodes with stable microstructures and uniform particle distribution. Electrochemical characterization exposed that the PVA-based cathode outperformed the PIB-based counterpart, achieving the theoretical capacity of 192 mAh·g⁻¹ even at 1C, whereas the PIB cathode reached a maximum capacity of 145 mAh.g⁻¹ at C/40. Post-mortem analysis confirmed the structural integrity of the cathodes. These findings demonstrate the viability of NMC955 as a high-capacity cathode material compatible with solid-state systems. Full article

This paper investigates the application of non-calcined metal tartrate as a novel alternative pore former to prepare functional ceramic composites to fabricate solid oxide fuel cells (SOFCs). Compared to carbonaceous pore formers, non-calcined pore formers offer high compatibility with various ceramic composites, providing better control over porosity and pore size distribution, which allows for enhanced gas diffusion, reactant transport and gaseous product release within the fuel cells’ functional layers. In this work, nanocrystalline gadolinium-doped ceria (GDC) and Ni-Gd-Ce-tartrate anode powders were prepared using a single-step co-precipitation synthesis method, based on the carboxylate route, utilising ammonium tartrate as a low-cost, environmentally friendly precipitant. The non-calcined Ni-Gd-Ce-tartrate was used to fabricate dense GDC electrolyte pellets (5–20 μm thick) integrated with a thin film of Ni-GDC anode with controlled porosity at 1300 °C. The dilatometry analysis showed the shrinkage anisotropy factor for the anode substrates prepared using 20 wt. The percentages of Ni-Gd-Ce-tartrate were 30 wt.% and 40 wt.%, with values of 0.98 and 1.01, respectively, showing a significant improvement in microstructural properties and pore size compared to those fabricated using a carbonaceous pore former. The results showed that the non-calcined pore formers can also lower the sintering temperature for GDC to below 1300 °C, saving energy and reducing thermal stresses on the materials. They can also help maintain optimal material properties during sintering, minimising the risk of unwanted chemical reactions or contamination. This flexibility enables the versatile designing and manufacturing of ceramic fuel cells with tailored compositions at a lower cost for large-scale applications. Full article

Solid-state electrolytes (SSEs) have emerged as a promising solution for next-generation lithium-ion batteries due to their excellent safety and high energy density. However, their practical application is still hindered by critical challenges such as their low ionic conductivity and high interfacial resistance at room temperature. The innovative application of 3D printing in the field of electrochemistry, particularly in solid-state electrolytes, endows energy storage devices with attractive characteristics. In this study, ceramic-in-gel polymer electrolytes (GPEs) based on PVDF-HFP/PAN@LLZTO were fabricated using a direct ink writing (DIW) 3D printing technique. Under the optimal printing conditions (printing speed of 40 mm/s and fill density of 70%), the printed electrolyte exhibited a uniform and dense sponge-like porous structure, achieving a high ionic conductivity of 5.77 × 10⁻⁴ S·cm⁻¹, which effectively facilitated lithium-ion transport. A structural analysis indicated that the LLZTO fillers were uniformly dispersed within the polymer matrix, significantly enhancing the electrochemical stability of the electrolyte. When applied in a LiFePO₄|GPEs|Li cell configuration, the electrolyte delivered excellent electrochemical performance, with high initial discharge capacities of 168 mAh·g⁻¹ at 0.1 C and 166 mAh·g⁻¹ at 0.2 C, and retained 92.8% of its capacity after 100 cycles at 0.2 C. This work demonstrates the great potential of 3D printing technology in fabricating high-performance GPEs. It provides a novel strategy for the structural design and industrial scalability of lithium-ion batteries. Full article

Gel-polymer electrolytes offer a promising route toward safer and more stable sodium-ion batteries, but conventional polymer systems often suffer from low ionic conductivity and limited voltage stability. In this study, we developed composite GPEs by embedding methylammonium lead chloride (CH₃NH₃PbCl₃, MPCl) into a UV-crosslinked ethoxylated trimethylolpropane triacrylate (ETPTA) matrix, with sodium alginate (SA) as an ionic conduction enhancer. Three types of membranes—GPE-P, GPE-El, and GPE-Eh—were synthesized and systematically compared. Among them, the high-MPCl formulation (GPE-Eh) exhibited the best performance, achieving a high ionic conductivity of 2.14 × 10⁻³ S·cm⁻¹, a sodium-ion transference number of 0.66, and a wide electrochemical window of approximately 4.9 V vs. Na⁺/Na. In symmetric Na|GPE|Na cells, GPE-Eh enabled stable sodium plating/stripping for over 600 h with low polarization. In Na|GPE|NVP cells, it delivered a high capacity retention of ~79% after 500 cycles and recovered ~89% of its initial capacity after high-rate cycling. These findings demonstrate that the perovskite–polymer composite structure significantly improves ion transport, interfacial stability, and electrochemical durability, offering a viable path for the development of next-generation quasi-solid-state sodium-ion batteries. Full article

Silicon oxide–graphite is a promising high-capacity anode material for next-generation lithium-ion batteries (LIBs). However, despite using a small fraction (≤5%) of Si, it suffers from a short cycle life owing to intrinsic swelling and particle pulverization during cycling, making practical application challenging. High-nickel (Ni ≥ 80%) oxide cathodes for high-energy-density LIBs and their operation beyond 4.2 V have been pursued, which requires the anodic stability of the electrolyte. Herein, we report a nonflammable multi-functional fluorinated ester–based liquid electrolyte that stabilizes the interfaces and suppresses the swelling of highly loaded 5 wt% SiO–graphite anode and LiNi_0.88Co_0.08Mn_0.04O₂ cathode simultaneously in a 3.5 mAh cm⁻² full cell, and improves cycle life and battery safety. Surface characterization results reveal that the interfacial stabilization of both the anode and cathode by a robust and uniform solid electrolyte interphase (SEI) layer, enriched with fluorinated ester-derived inorganics, enables 80% capacity retention of the full cell after 250 cycles, even under aggressive conditions of 4.35 V, 1 C and 45 °C. This new electrolyte formulation presents a new opportunity to advance SiO-based high-energy density LIBs for their long operation and safety. Full article

Solid polymer electrolytes (SPEs) have garnered significant attention due to their potential in all-solid-state batteries (ASSBs). However, adoption remains constrained by challenges such as low thermal stability and limited ionic conductivity. Here, we report on an electrospun (PAN/PEO)- conductive salt (LiBF₄) system, where the influence of varying polyacrylonitrile (PAN) and polyethylene oxide (PEO) ratios, along with different plasticizer concentrations, is evaluated. Notably, the 50:50 PAN/PEO sample exhibited the highest ionic conductivity, reaching 1∙10⁻² S/cm at 55 °C. This system also balanced conductivity and processability. Succinonitrile (SN) significantly influenced the morphology and conductivity. Samples with increased SN content showed enhanced capacity in symmetrical cells, achieving ~140 mAs/cm² for an 18:9:1 polymer (PAN/PEO):SN:conductive salt (LiBF₄) composition. The enhanced lithium-ion conductivity of the electrospun blend is attributed to the deliberate use of an unmixable PAN–PEO system. Their immiscibility creates well-defined interfacial regions within fibers, acting as efficient lithium-ion pathways. These findings support electrospun polymer blends as promising candidates for high-performance SPEs for ASSB development. Full article

Solid oxide fuel cells (SOFCs) have been considered as alternative energy conversion devices because of their high energy conversion efficiency, fuel flexibility, and cost efficiency without precious metal catalysts. In current SOFCs, the cermet anode consists of nickel and ion-conducting ceramic materials, and solid oxide electrolytes and ceramic cathodes have been used. SOFCs normally operate at high temperatures because of the lower ion conductivity of ceramic components at low temperatures, and they have weaknesses in terms of mechanical strength and durability against thermal shock originating from the properties of ceramic materials. To solve these problems, metal-supported solid oxide fuel cells (MS-SOFCs) have been designed. SOFCs using metal substrates, such as Ni-based and Cr-based alloys, provide significant advantages, such as a low material cost, ruggedness, and tolerance to rapid thermal cycling. In this article, SOFCs are introduced briefly, and the types of metal substrate used in MS-SOFCs, as well as the advantages and disadvantages of each metal support, are reviewed. Full article

This work presents a comprehensive investigation into the interfacial charge storage mechanisms and lithium-ion transport behavior of Li-metal all-solid-state batteries (ASSBs) employing LiFePO₄ (LFP) cathodes fabricated via alternating current electrophoretic deposition (AC-EPD) and Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) as the solid-state electrolyte. We demonstrate that optimal sintering improves the LATP–LFP interfacial contact, leading to higher lithium diffusivity (~10⁻⁹ cm²∙s⁻¹) and diffusion-controlled kinetics (b ≈ 0.5), which directly translate to better rate capability. Structural and electrochemical analyses—including X-ray diffraction, scanning electron microscopy, cyclic voltammetry, and rate capability tests—demonstrate that the cell with LATP sintered at 900 °C delivers the highest Li-ion diffusivity (~10⁻⁹ cm²∙s⁻¹), near-ideal diffusion-controlled behavior (b-values ~0.5), and superior rate capability. In contrast, excessive sintering at 1000 °C led to reduced diffusivity (~10⁻¹⁰ cm²∙s⁻¹). The liquid electrolyte system showed higher b-values (~0.58), indicating the inclusion of surface capacitive behavior. The correlation between b-values, diffusivity, and morphology underscores the critical role of interface engineering and electrolyte processing in determining the performance of solid-state batteries. This study establishes AC-EPD as a viable and scalable method for fabricating additive-free LFP cathodes and offers new insights into the structure–property relationships governing the interfacial transport in ASSBs. Full article

In this study, a novel anode-supported solid oxide fuel cell (SOFC) comprising a Bi₂O₃-doped NiO-ScSZ anode and an ScSZ electrolyte was successfully fabricated via a low-temperature co-sintering process at 1300 °C. The incorporation of 3 wt% Bi₂O₃ effectively promoted the sintering of both the anode support and electrolyte layer, resulting in a dense, gas-tight electrolyte and a mechanically robust porous anode support. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the formation of phase-pure, highly crystalline ScSZ with an optimized microstructure. Electrochemical performance measurements demonstrated that the fabricated cells achieved excellent power density, reaching a peak value of 0.861 W cm⁻² at 800 °C under humidified hydrogen fuel conditions. The cells maintained stable performance under dry methane operation, with a maximum power density of 0.624 W cm⁻² at 800 °C, indicating resistance to carbon deposition. Gas chromatographic analyses further revealed that the Bi₂O₃-doped NiO-ScSZ anode facilitated earlier and more stable electrochemical oxidation of methane-derived species compared with the conventional NiO-YSZ system, even under conditions of an elevated methane partial pressure. These findings demonstrate that Bi₂O₃ co-doping, combined with low-temperature co-sintering, provides an effective approach for fabricating high-performance intermediate-temperature SOFCs with enhanced structural integrity and electrochemical stability. The developed methodology presents a promising pathway toward achieving cost-effective and durable SOFC technologies. Full article

Internal Dry Reforming of Methane (IDRM) in biogas fed Solid Oxide Fuel Cells (SOFCs) was investigated on Fe-Au modified Ni/GDC electrolyte-supported cells at 900 and 850 °C. The aim was to clarify the synergistic interaction between Fe and Au, focusing on the effect of X wt.% of Au loading (where X = 1 or 3 wt.%) in binary Au-Ni/GDC and ternary 0.5 wt.% Fe-Au-Ni/GDC fuel electrodes. The investigation combined i-V, Impedance Spectroscopy and Gas Chromatography electrocatalytic measurements. It was found that modification with 0.5Fe-Au enhanced significantly the electrocatalytic activity of Ni/GDC for the IDRM reaction, whereas the low wt.% Au content had the most promoting effect. The positive interaction of 0.5 wt.% Fe with 1 wt.% Au increased the conductivity of Ni/GDC and enhanced the corresponding IDRM charge transfer electrochemical processes, especially those in the intermediate frequency region. Comparative long-term measurements, between cells comprising Ni/GDC and 0.5Fe-1Au-Ni/GDC, highlighted the significantly higher IDRM electrocatalytic activity of the modified electrode. The latter operated for almost twice the time (280 h instead of 160 h for Ni/GDC) with a lower degradation rate (0.44 mV/h instead of 0.51 mV/h). Ni/GDC degradation was ascribed to inhibited charge transfer processes in the intermediate frequencies region and to deteriorated ohmic resistance. Stoichiometric analysis on the (post-mortem) surface state of each fuel electrode showed that the wt.% content of reduced nickel on Ni/GDC was lower, compared to 0.5Fe-1Au-Ni/GDC, verifying the lower re-oxidation degree of the latter. This was further correlated to the hindered H₂O production during IDRM operation, due to the lower selectivity of the modified electrode for the non-desired RWGS reaction. Full article

An analysis of entropy generation and a performance comparison are carried out for a solid oxide fuel cell with an embedded porous pipe in the air supply channel of a mono-block-layer-build geometry (MOLB-PPA SOFC) and a planar geometry with trapezoidal baffles inside the fuel and air channels (P-TBFA SOFC). The results for power density at different current densities are discussed. Also, a comparison of the field of species concentration, temperature, and current density on the electrode–electrolyte interface is analyzed at a defined power density. Finally, a comparison of maps of the local entropy generation rate and the global entropy generation due to heat transfer, fluid flow, mass transfer, activation loss, and ohmic loss are studied. The results show that the MOLB-PPA SOFC reaches a 7.5% higher power density than the P-TBFA SOFC. Furthermore, the P-TBFA SOFC has a more homogeneous temperature distribution than the MOLB-type SOFC. The entropy generation analysis indicates that the MOLB-PPA SOFC exhibits lower global entropy generation due to heat transfer compared to the P-TBFA SOFC. The entropy generation due to ohmic losses is predominant for both geometries. Finally, the total irreversibilities are 24.75% higher in the P-TBFA SOFC than in the MOLB-PPA SOFC. Full article