Search Results (2,701)

Vanadium dioxide (VO₂) is a prominent active material for reconfigurable nanophotonics because its reversible metal-insulator transition produces large changes in complex refractive index and electrical conductivity. The usable phase contrast, however, is not an intrinsic constant: it is governed by defect type and location, vanadium valence, oxygen stoichiometry, strain, crystallographic orientation, dimensionality, and the chemical, electrical, optical, and thermal boundary conditions imposed by interfaces. This focused narrative review develops a defect- and interface-centred framework linking VO₂ phase physics to device-level optical modulation. Bulk, surface, grain-boundary, and heterointerface defects are distinguished, together with their effects on carriers, V-V bonding, phase stability, optical loss, and cycling reliability. Epitaxial and polycrystalline films, ultrathin layers, and nanostructures are compared across the visible, near-infrared, mid-infrared, and terahertz ranges. Thermal, optical, electrical, electrostatic, electrochemical, ionic, strain, and ferroelectric activation pathways are then compared according to volatility, speed, retention, reversibility, and endurance. Representative free-space metasurfaces, guided-wave modulators, adaptive emitters, and photonic memories are benchmarked separately to avoid mixing incomparable performance definitions. The resulting analysis shows that optical modulation, insertion loss, thermal overhead, ambient stability, and endurance are coupled through the same defect and interface landscape. Progress, therefore, requires coordinated control of phase purity, local chemistry, interface energetics, thermal transport, and architecture-specific performance reporting. Full article

Carbon-fiber structural batteries represent a class of multifunctional energy-storage systems that integrate electrochemical energy storage with mechanical load-bearing capability. Unlike conventional batteries, which are mainly evaluated based on cell-level energy density, structural batteries provide new opportunities for system-level weight reduction by reducing inactive structural mass, improving space utilization, and enabling distributed energy storage within integrated structures. In recent years, substantial progress has been achieved in carbon-fiber electrodes, structural electrolytes, laminated devices, electrolyte topology engineering, and fully carbon-fiber structural batteries. Nevertheless, most reported advances have been demonstrated under relatively ideal static testing conditions, while maintaining multifunctional performance under manufacturing and long-term service conditions remains a critical challenge. This review systematically examines the development of carbon-fiber structural batteries from a reliability perspective. First, the system-level motivations and technological evolution are introduced, and existing architectures are categorized according to their integration depth and degree of multifunctional coupling. Carbon-fiber electrodes are then discussed with emphasis on balancing capacity, ion transport, cycling stability, mechanical property retention, interfacial robustness, and manufacturing scalability. Furthermore, structural electrolytes are reviewed from the viewpoint of topology-enabled regulation of ion transport and load transfer, with particular focus on the intrinsic trade-off between ionic conductivity and mechanical modulus. In addition, manufacturing routes and device architectures are analyzed from the perspective of multifunctionality-degrading defects, including voids, dry regions, coating cracks, weak interfaces, and current-collector discontinuities. Finally, retained multifunctionality is used as a reliability-oriented evaluation criterion to examine the preservation of electrochemical, mechanical, interfacial, and safety functions, with particular emphasis on the carbon-fiber-specific failure chain linking interfacial and manufacturing heterogeneities to multifunctionality-degrading defects, coupled-field localization, and damage propagation. This review emphasizes that reliable carbon-fiber structural batteries require application-specific and coordinated optimization of materials, interfaces, electrolyte topology, coupled degradation behavior, and validation protocols. Full article

Commercial polyolefin separators for lithium-ion batteries (LIBs) exhibit only inadequate wettability and thermal stability. In large-scale production, high electrolyte uptake and wetting are essential to enable rapid electrolyte filling during battery assembly to reduce costs. In addition, it is imperative to develop separators with enhanced thermal stability for improved performance and safety. The focus of this study is the structure–property–performance relationship of separator coatings. Platelet-shaped glass particles are utilized as inorganic coating material for polyethylene (PE) separators. Styrene–butadiene rubber (SBR) was selected as binder due to its high thermal stability. Hybrid separators are prepared using a colloidal coating technology employing a water-based slurry. As the excessive use of binder in the coating can block pores, precise control of the binder content was essential to maintain battery performance. The resulting separators with an optimized binder content of 1 wt.% in the coating demonstrate high porosity, instantaneous wetting with electrolyte, and a 25 K increase in onset temperature for shrinkage. The utilization of glass platelets with an aspect ratio of 10 as coating material provided the best balance among processability, coating homogeneity, thermal stability, ionic conductivity, and cycling performance under the investigated processing conditions. Full article

Sodium metal anodes (SMAs) are regarded as the most promising anode materials for next-generation high-energy-density sodium metal batteries, owing to their ultrahigh theoretical specific capacity (1166 mAh g⁻¹) and low electrochemical potential (−2.71 V vs. SHEs). However, their practical application is severely hindered by a series of interrelated challenges, including unstable solid electrolyte interphase (SEI) films, severe volume fluctuations arising from their hostless nature, uncontrollable dendrite growth, and the consequent low Coulombic efficiency and short cycle life. This review systematically summarizes recent progress in stabilizing SMAs through three major categories of strategies: current collector engineering, which involves the design of planar, three-dimensional, and gradient architectures to regulate the local current density and Na⁺ flux, thereby guiding uniform nucleation and enabling “bottom-up” dendrite-free deposition; electrolyte engineering, which focuses on optimizing solvents, salts, and functional additives to tailor the solvation structure, construct robust inorganic-rich SEI layers, and utilize electrostatic shielding effects to suppress dendrite formation; and artificial SEI engineering, which aims to pre-construct inorganic or inorganic–organic hybrid protective layers that establish a physicochemical barrier between the electrode and electrolyte, combining high ionic conductivity, superior mechanical strength, and sufficient flexibility. Finally, we provide a critical perspective on the remaining challenges and outline future research directions, emphasizing the importance of in situ/operando characterization, synergistic multi-strategy integration, breakthroughs in high areal capacity and high-rate performance, and artificial intelligence-driven material discovery for the practical implementation of SMAs. Full article

Zeolitic imidazolate framework-8 (ZIF-8) has emerged as a material for electrochemical energy conversion, serving dual primary roles in fuel cell technologies: (i) as an electrocatalyst precursor for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) through pyrolysis-derived N-doped porous carbons and metal–nitrogen–carbon (M–N–C) structures, and (ii) as a membrane component that enhances proton conductivity via imidazole-mediated Grotthuss hopping while suppressing fuel crossover through molecular sieving. This comprehensive review systematically evaluates ZIF-8 performance across multiple fuel cell types, including primarily proton exchange membrane fuel cells (PEMFCs), as well as direct methanol fuel cells (DMFCs), anion exchange membrane fuel cells (AEMFCs), and microbial fuel cells (MFCs), while also covering related electrochemical applications such as zinc–air batteries, supercapacitors, and water splitting devices, where ZIF-8-derived materials demonstrate improved catalytic activity. The review examines structure–performance relationships, highlighting strategies such as heteroatom doping, bimetallic synergy, hierarchical porosity engineering, and polymer composite fabrication that have enabled ZIF-8-based catalysts to achieve ORR half-wave potentials and PEMFC power densities, rivaling commercial Pt/C systems. ZIF-8 composite membranes demonstrate proton conductivities in polybenzimidazole systems and effective methanol blocking. Despite improved progress, challenges persist regarding long-term stability, scalable synthesis, and degradation mechanism understanding. This review critically analyzes recent advances, identifies performance-limiting factors across applications, and outlines future research directions for developing commercially viable ZIF-8-based electrochemical technologies. Full article

Flexible and stretchable electronics inevitably undergo stretching, compression, bending and torsion when conformally attached to skin, soft tissues and dynamic organs. While deformation-induced electrical variations act as target signals for motion sensors, they cause resistance/impedance drift, baseline shift and sensitivity degradation in physiological electrodes, temperature/chemical sensors, interconnects and stimulation devices, leading to motion artifacts and reduced long-term reliability. Hydrogels are pivotal materials for soft bioelectronic interfaces owing to their high water content, low modulus, tissue compatibility and ionic conductivity. However, their conductive networks are susceptible to structural reconstruction under deformation, dehydration, swelling and cyclic fatigue, meaning that stretchability is by no means equivalent to strain insensitivity. This review focuses on stable resistance/impedance and functional output within a specified strain window, this paper reviews three representative material systems, liquid metal (LM)-based composite hydrogels, conductive polymer/elastic network composite hydrogels, and hydrogen-bonded isotropic architectures. It further summarizes three design strategies—geometric and functional compensation, mechanical decoupling and strain isolation, and interfacial engineering for conductive network stabilization—and discusses their applications in wearable epidermal and implantable bioelectronics. Finally, unified evaluation metrics for strain insensitivity are proposed, with future directions covering high-conductivity–low-modulus synergy, long-term water/ionic stability, robust soft-hard interfaces, multiaxial deformation tolerance and scalable manufacturability. Full article

Chitosan-based films and nanocomposites have attracted growing attention as renewable, biodegradable, and chemically adaptable materials for sustainable electronics. This systematic review synthesizes evidence on chitosan-containing functional films, membranes, polymer electrolytes, dielectric substrates, optoelectronic nanocomposites, electrochemical sensors, impedance sensors, and smart-device interfaces. This review adopts a structure–property–function perspective, examining molecular interactions, crystallinity, amorphous fraction, morphology, filler dispersion, processing routes, and interfacial architecture in relation to optical, electrical, dielectric, electrochemical, and sensing performance. The literature was identified using Scopus-oriented Boolean searches combining chitosan/chitin terms with thin-film or membrane descriptors, electronic-function terms, and structure–property terminology. Relevant studies were grouped into four themes: structural engineering and processing, dielectric/electrical/impedance properties, optoelectronic and band-gap engineering, and electrochemical/impedance-sensing applications. The synthesis shows that chitosan becomes electronically functional when its semi-crystalline, hydrogen-bonded matrix is modified through salt doping, plasticization, blending, conductive polymers, carbon materials, metal oxides, metal–organic frameworks, or noble metal nanoparticles. Reported advances include ionic conductivities up to 10⁻³ S/cm, improved dielectric behavior, band-gap reduction, and low detection limits. However, inconsistent reporting of material source, molecular weight, degree of deacetylation, film thickness, humidity, stability, and sustainability metrics limits comparability. Full article

Cutaneous wound healing is governed by dynamically interacting mechanical, redox, and bioelectrical signals that regulate cell migration, inflammation, angiogenesis, extracellular-matrix remodeling, and tissue regeneration. Hydrogels are increasingly engineered to modulate these cues; however, most systems are still described through independently measured properties such as stiffness, antioxidant activity, and conductivity, without demonstrating functional coupling among them. This review examines regenerative hydrogels from a cross-domain perspective, integrating the biological basis of mechanotransduction, redox signaling, endogenous bioelectricity, and their molecular convergence with the network-level mechanisms that control hydrogel behavior. Particular emphasis is placed on dynamic crosslinking, viscoelastic relaxation, hydration, redox-active chemistry, ionic and electronic transport, conductive and piezoelectric phases, and degradation-dependent evolution of material function. A conceptual hierarchy is proposed to distinguish property coexistence, structural integration, directional transduction, and adaptive feedback, together with experimental criteria and quantitative approaches for evaluating coupling. Current evidence indicates that mechanoelectrical coupling is the most mature, whereas mechanoredox and redox–electrical interactions remain less systematically quantified. Moving beyond descriptive multifunctionality toward controllable cross-domain transduction may enable hydrogels to function as adaptive soft interfaces capable of responding to the evolving physicochemical conditions of cutaneous regeneration. Full article

Solid-state sodium metal batteries are promising for large-scale energy storage owing to their high safety, abundant sodium resources, and low material cost. However, NASICON-type solid-state electrolytes, such as Na₃Zr₂Si₂PO₁₂, still suffer from limited room-temperature ionic conductivity and poor ceramic densification. Herein, a multivalent co-doping strategy using Zn²⁺, Sc³⁺, Hf⁴⁺, and Nb⁵⁺ was employed to regulate the crystal structure, sintering behavior, and Na⁺ transport properties of NASICON electrolytes. The effects of isovalent and aliovalent dopants were systematically investigated by XRD, Rietveld refinement, SEM-EDS, bond-valence-site calculations, and electrochemical impedance spectroscopy. The optimized monoclinic Na_3.167Zn_0.167Hf_0.167Zr_1.5Nb_0.167Si₂PO₁₂ electrolyte delivered a room-temperature total ionic conductivity of 1.16 mS cm⁻¹ and an activation energy of 0.35 eV, mainly due to optimized Na⁺ migration-channel geometry and enhanced ceramic densification. Na||Na symmetric cells exhibited stable cycling for 500 h with a maximum polarization voltage of 20 mV. Furthermore, solid-state Na||Na₃V₂(PO₄)₃ cells retained 95% capacity after 624 cycles at 1 C. This work provides a feasible doping strategy for advanced NASICON electrolytes and solid-state sodium metal batteries. Full article

Ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) provide complementary, but non-unique, observations of concrete and masonry conditions. GPR is primarily sensitive to dielectric contrasts, interfaces, reinforcement geometry and electromagnetic attenuation, whereas electrical measurements respond to ionic conduction, moisture state, material connectivity and electrode configuration. This paper presents a structured critical review updated to 21 July 2026. It distinguishes surface or bulk resistivity measurements from electrical resistance tomography around specimens and from multi-electrode geophysical ERT, an important terminological separation that is frequently blurred in the literature. This review’s contribution is a terminological separation of electrical measurement classes, an evidence-coding scheme that distinguishes corroboration from independent validation, and a staged, conditional research agenda built from that scheme; it is not a claim that GPR–ERT integration is routinely sufficient on its own. Verified evidence is synthesised across reinforced concrete, masonry, coastal infrastructure, laboratory calibration, field validation and forward modelling. The review shows that GPR is mature for reinforcement mapping and conditional detection of interfaces and delamination, while resistivity methods are well established for durability-related screening. True ERT can image spatial conductivity changes associated with moisture ingress and cracks, but inversion regularisation, electrode contact, reinforcement and three-dimensional effects limit resolution and quantitative recovery. Integrated GPR–ERT studies now include controlled masonry experiments, heritage structures, a field heritage pier and laboratory calibration on reinforced concrete; therefore, the principal remaining gap is not the absence of integration. It is the shortage of independent destructive field verification, scale-aware transfer rules and uncertainty-calibrated decision thresholds across structural types. A revised evidence matrix and detectability taxonomy show that neither method directly identifies active corrosion or chloride concentration. The paper concludes with a staged research agenda based on co-registration, physics-informed feature extraction, forward-modelled resolution assessment and targeted ground truth. Full article

Sulfide solid electrolytes (SSEs) are promising for all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity, mechanical deformability, and interfacial compatibility. However, SSE interfaces with anodes, cathodes, conductive additives, and current collectors are unstable, triggering safety failures like capacity degradation, internal resistance build-up, thermal runaway, and short circuits. This review summarizes recent progress on interface-induced safety failure mechanisms in sulfide-based ASSLBs, focusing on interface types, failure mechanisms, and thermal/mechanical degradation under multi-field coupling. We survey interface modification strategies and highlight advanced characterization techniques for probing interfacial phenomena. Key challenges and future research directions are discussed. Integrating recent findings, we identify interfacial instability as the primary bottleneck governing safety failures, providing a theoretical and technical framework for rational interface design, performance optimization, and safety enhancement. Throughout this review, we use SSE as the standard abbreviation for sulfide solid electrolytes. Full article

Poly(vinyl alcohol) (PVA)/sodium alginate (SA) dual-network hydrogels were prepared via the freeze–thaw method. Tensile testing, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and fiber-optic spectroscopy were employed for material characterization, and multiple metal ions were screened to optimize mechanical properties and ionic conductivity. The results showed that, at PVA:SA mass ratio of 2:1, the hydrogel achieved 163% elongation and 0.18 MPa tensile strength. Ca²⁺ crosslinking formed an enhanced structure with mechanical properties of 170% elongation and 0.21 MPa strength, and ionic conductivity (0.69 S/m). Combined with colloidal photonic crystal (PC) templates, the PVA/SA-PC film exhibited an inverted opal structure, showing sensitive color response (green to red) and diffraction red-shift toward Ca²⁺. The conductive film could power a small bulb, demonstrating potential for portable visual sensing applications. Full article

Dissolved oxygen concentration is a key parameter determining the oxidation and corrosion behavior of structural materials in lead-based fast reactor coolants. Therefore, achieving high-precision in-situ oxygen measurement in LBE systems is a fundamental technical requirement for implementing oxygen-controlled corrosion protection. Currently, nuclear-grade Bi/Bi₂O₃ solid-state electrochemical oxygen sensors have a minimum effective operating temperature of 350 °C, which prevents them from meeting the real-time oxygen monitoring needs under low-temperature conditions. This temperature limitation has become a major bottleneck for the engineering application of oxygen control technology. To address these requirements and challenges, this study develops a novel electrochemical oxygen sensor based on an 8 mol% Y₂O₃-stabilized ZrO₂ (8YSZ) solid electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3±δ (LSCF) electrode system. Comparative experiments with Bi/Bi₂O₃ sensors are conducted to quantitatively assess the advantages of the LSCF/Air sensor in low-temperature applications within 205~550 °C. Furthermore, considering the irradiation environment in nuclear reactors, oxygen ion irradiation was employed as an accelerated simulation method to preliminarily investigate the electrochemical transport properties of 8YSZ after irradiation. The effects of oxygen ion irradiation on the apparent impedance and apparent oxygen ion conductivity of 8YSZ were evaluated. The results show that the LSCF/Air oxygen sensor has the potential to extend the lower operating-temperature limit of 8YSZ-based oxygen sensors in static, oxygen-saturated LBE environments. Oxygen ion irradiation increased the apparent impedance and decreased the apparent ionic conductivity of the tested 8YSZ samples. These results provide preliminary experimental data for the development of oxygen sensors for oxygen monitoring and corrosion control in liquid-metal-cooled reactor systems over a wider temperature range. Full article

To improve the inherently low electronic and ionic conductivity of lithium iron phosphate (LFP) cathode materials, the synergistic modification of Al doping and carbon coating has been proven to be an effective strategy. However, the doping effects of different aluminum (Al) sources have not been systematically compared, and the mechanism of the synergistic effect between the characteristics of the Al source and the synthesis process remains poorly understood. To address this, the present study systematically investigated the effects of three Al sources on the structure and electrochemical performance of LFP/C composites under two sintering processes: static and dynamic. Phase and microstructure characterizations confirmed the successful doping of Al³⁺ and the formation of an effective carbon coating. Electrochemical tests indicated that the choice of Al source and sintering process was strongly coupled: in the dynamic fluidized-bed process, which is highly characterized by efficient mass and heat transfer, Al(OH)₃, due to its lower thermal decomposition temperature and the release of active H₂O, promoted uniform Al³⁺ doping and optimized the quality of the carbon coating, thereby achieving the best overall performance. By contrast, under the sluggish reaction kinetics of static sintering, the chemically stable Al₂O₃ achieved ordered doping through slow solid-state diffusion, demonstrating the best cycling stability. In both processes, the overly stable AlPO₄ failed to release Al³⁺ effectively, resulting in limited performance improvement. This work reveals the key principle that the intrinsic reactivity of the Al source must be matched with the kinetics of the sintering process, deepens mechanistic understanding of the doping modification, and provides clear experimental evidence for the selection of the optimal Al source under different synthesis processes. Full article

The design of efficient small-scale hydrogen energy storage systems requires balancing hydrogen production rate, electrical efficiency, and system simplicity. This study experimentally investigates the energetic compromise imposed by separator material and electrolyzer architecture through a comparative analysis of finite-gap alkaline, finite-gap acidic, and zero-gap proton exchange membrane (PEM) electrolyzers. Zirfon^® Pearl 500 (Agfa, Mortsel, Belgium) diaphragms were employed in alkaline electrolysis using 25 wt.% KOH, whereas Nafion™ 117 (Chemours, Wilmington, DE, USA) membranes were used in both finite-gap acidic electrolysis (2.55 M H₂SO₄) and a commercial five-cell zero-gap PEM electrolyzer supplied with deionized water. Electrochemical performance was evaluated in terms of polarization behavior, apparent resistance, hydrogen production rate, Faradaic efficiency, and energy conversion efficiency. The zero-gap PEM architecture exhibited the best electrochemical performance, with an apparent resistance of only 0.138 Ω per cell, corresponding to reductions of approximately 43-, 51-, and 64-fold compared with the finite-gap PEM, stainless steel/Zirfon alkaline, and nickel/Zirfon alkaline configurations, respectively. The zero-gap electrolyzer delivered currents from 1.53 to 10.0 A while operating below 2.8 V, demonstrating the benefit of minimizing the ionic transport path. In contrast, the finite-gap acidic configuration achieved higher hydrogen production rates than the alkaline system owing to the superior proton conductivity of Nafion™ 117, whereas the alkaline Ni/Zirfon configuration reached the highest Faradaic efficiency (≈98%) and energy conversion efficiency (≈36%) because of improved gas separation and reduced hydrogen crossover. Electrochemical impedance spectroscopy further revealed that the normalized ohmic resistance of the zero-gap PEM cell was only 0.029 Ω, with charge-transfer processes accounting for approximately 96.2% of the total impedance. These results demonstrate that separator properties and cell architecture govern the trade-off between reaction kinetics and energy efficiency, providing practical guidelines for selecting electrolyzer configurations dedicated to decentralized and small-scale hydrogen energy storage. Full article