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Lithium-ion batteries are superior energy storage devices that are widely utilized in various fields, from electric cars to small portable electric devices. However, their susceptibility to thermal runaway necessitates improvements in battery case materials to improve their safety. This study used electrochemical analyses, including open-circuit potential (OCP), potentiodynamic polarization, and critical pitting temperature (CPT) analyses, to investigate the corrosion resistance of super duplex stainless steel (SAF 2507) applied to battery cases in relation to post-weld heat treatment (PWHT) time. The microstructure during the manufacture, laser welding, and PWHT was analyzed using field-emission scanning electron microscopy, X-ray diffraction, and electron backscatter diffraction, and the chemical composition was analyzed using dispersive X-ray spectroscopy and electron probe micro-analysis. The PWHT increased the volume fraction of austenite from 5% to 50% over 3 min at 1200 °C; this increased the OCP from −0.21 V to +0.03 V, and increased the CPT from 56 °C to 73 °C. The PWHT effectively improved the corrosion resistance, laying the groundwork for utilizing SAF 2507 in battery case materials. But the alloy segregation and heterogeneous grain morphology after PWHT needs improvement. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs), a relatively new class of materials, have attracted significant attention in materials science owing to their unique properties and potential applications. High entropy stabilizes the phase of a solid solution over a wide range of chemical compositions, yielding unique properties superior to those of conventional alloys. Therefore, this study analyzed the microstructure and electrochemical behavior of HEAs (Cantor) to evaluate their corrosion resistance, according to their manufacturing process (casting, cold rolling, and annealing). The microstructural morphologies and sizes were analyzed using electron backscatter diffraction. The electrochemical behavior was examined using open circuit potential measurements, electrochemical impedance spectroscopy, potentiodynamic polarization tests, and critical pitting temperature measurements using a potentiostat. The casting process formed a nonuniform microstructure (average grain size = 19 μm). The cold rolling process caused the formation of fine grains (size = 4 μm). A uniform microstructure (grain size > 151 μm) was formed after heat treatment. The corrosion resistance of the HEAs was determined from the passivation layer formed by Cr oxidation. These microstructural differences resulted in variations in the electrochemical behavior. Microstructural and electrochemical analyses are crucial because HEAs have diverse potential applications. Therefore, this study contributes to future improvements in HEA manufacturing processes. [ABSTRACT FROM AUTHOR]

Li-ion batteries used in portable electronic devices and electric vehicles require high safety standards, necessitating the use of high-performance structural materials for battery casings. Super duplex stainless steel (SDSS) is a structural material suitable for portable electronic products owing to its excellent strength and corrosion resistance. SDSS AISI2507 was used to construct a Li-ion battery casing, a Ag coating was applied via physical vapor deposition (PVD) after the heat treatment of AISI2507 with or without a secondary phase, and the coating thickness was controlled by varying the PVD time. The thickness of the Ag coating layer increased proportionally with time, thereby enhancing the electrical conductivity. The structure and coating behavior were confirmed using FE-SEM, XRD, and GDS. The secondary phase was crystallized by the segregation of the alloy and formed a BCC structure. The FCC lattice structure exhibited excellent coating behavior on the austenite (FCC structure) of AISI2507. Conversely, the secondary phase exhibited low adhesion owing to differences in composition and crystal structure. However, the Ag coating layer on AISI2507 exhibited excellent electrical conductivity, outperforming conventional Ni-plated Li-ion battery casings comprising AISI304. However, the precipitation of the secondary phase must be controlled, as the formation of the secondary phase acts as a factor that decreases electrical conductivity from 58.8 to 53.6 (ICAS) %. The excellent performance of Ag-coated AISI2507 makes it suitable for the fabrication of enhanced Li-ion battery casings. [ABSTRACT FROM AUTHOR]

Aluminum, traditionally the primary material for battery casings, is increasingly being replaced by UNS S 30400 for enhanced safety. UNS S 30400 offers superior strength and corrosion resistance compared to aluminum; however, it undergoes a phase transformation owing to stress during processing and a lower high-temperature strength. Duplex stainless steel UNS S 32750, consisting of both austenite and ferrite phases, exhibits excellent strength and corrosion resistance. However, it also precipitates secondary phases at high temperatures, which are known to form through the segregation of Cr and Mo. Various studies have investigated the corrosion resistance of UNS S 32750; however, discrepancies exist regarding the formation and thickness of the passivation layer. This study analyzed the oxygen layer on the surface of UNS S 32750 after secondary-phase precipitation. The microstructure, volume fraction, chemical composition, and depth of O after the precipitation of the secondary phases in UNS S 32750 was examined using FE-SEM, EDS, EPMA and XRD, and the surface chemical composition and passivation layer thickness were analyzed using electron probe microanalysis and glow-discharge spectroscopy. This study demonstrated the segregation of alloy elements and a reduction in the passivation-layer thickness after precipitation from 25 μm to 20 μm. The findings of the analysis aid in elucidating the impact of secondary-phase precipitation on the passivation layer. [ABSTRACT FROM AUTHOR]

Super duplex stainless steel (SDSS) is a suitable structural material for various engineering applications due to its outstanding strength and corrosion resistance. In particular, its high-temperature strength can enhance the safety of electronic products and cars. SDSS AISI2507, known for its excellent strength and high corrosion resistance, was analyzed for its microstructure and electrochemical behavior at the ignition temperature of Li-ion batteries, 700 °C. At 700 °C, AISI2507 exhibited secondary phase precipitation values of 1% and 8% after 5 and 10 h, respectively. Secondary phase precipitation was initiated by the expansion of austenite, forming sigma, chi, and CrN phases. The electrochemical behavior varied with the fraction of secondary phases. Secondary phase precipitation reduced the potential (From −0.25 V to −0.31 V) and increased the current density (From 8 × 10−6 A/cm2 to 3 × 10−6 A/cm2) owing to galvanic corrosion by sigma and chi. As the fraction of secondary phases increased (From 0.0% to 8.1%), the open circuit potential decreased (From −0.25 V to −0.32 V). Secondary phase precipitation is a crucial factor in reducing the corrosion resistance of SDSS AISI2507 and occurs after 1 h of exposure at 700 °C. [ABSTRACT FROM AUTHOR]

The demand for Li-ion batteries has increased because of their extensive use in vehicles and portable electronic devices. This increasing demand implies greater interaction between batteries and humans, making safety a paramount concern. Although traditional batteries are fabricated using Al, recent efforts to enhance safety have led to the adoption of AISI304. The strength and corrosion resistance of AISI304 are greater than those of Al; however, issues such as stress-induced phase transformation and low high-temperature strength have been observed during processing. Duplex stainless steel SAF2507, which is characterized by a dual-phase structure consisting of austenite and ferrite, exhibits excellent strength and corrosion resistance. Although SAF2507 demonstrated outstanding high-temperature strength up to 700 °C, it precipitated a secondary phase. The precipitation of this secondary phase, believed to be caused by the precipitation of the carbides of Cr and Mo, has been extensively studied. Research on the precipitation of the secondary phase near 1000 °C has been conducted owing to the annealing temperature (1100 °C) of the SAF2507 solution. The secondary phase precipitates at approximately 1000 °C because of slow cooling rates. However, few studies have been conducted on the precipitation of the secondary phase at approximately 700 °C. This study analyzed the precipitation behavior of the secondary phase at 700 °C when SAF2507 was applied and assessed its safety during heat generation in Li-ion batteries. The precipitation behavior was analyzed using field emission scanning electron microscopy for morphology, energy-dispersive X-ray spectroscopy for composition, and X-ray diffraction for phase identification. [ABSTRACT FROM AUTHOR]

The development of Li-ion battery cases requires superior electrical conductivity, strength, and corrosion resistance for both cathode and anode to enhance safety and performance. Among the various battery case materials, super duplex stainless steel (SDSS), which is composed of austenite and ferrite as two-phase stainless steel, exhibits outstanding strength and corrosion resistance. However, stainless steel, which is an iron-based material, tends to have lower electrical conductivity. Nevertheless, nickel-plating SDSS can achieve excellent electrical conductivity, making it suitable for Li-ion battery cases. Therefore, this study analysed the plating behaviour of SDSS plates after nickel plating to leverage their exceptional strength and corrosion resistance. Electroless Ni plating was performed to analyse the plating behaviour, and the plating behaviour was studied with reference to different plating durations. Heat treatment was conducted at 1000 °C for one hour, followed by cooling at 50 °C/s. Post-heat treatment, the analysis of phases was executed using FE-SEM, EDS, and EPMA. Electroless Ni plating was performed at 60–300 s. The plating duration after the heat treatment was up to 300 s, and the behaviour of the materials was observed using FE-SEM. The phase analysis concerning different plating durations was conducted using XRD. Post-heat treatment, the precipitated secondary phases in SAF2507 were identified as Sigma, Chi, and CrN, approximating a 13% distribution. During the electroless Ni plating, the secondary phase exhibited a plating rate equivalent to that of ferrite, entirely plating at around 180 s. Further increments in plating time displayed growth of the plating layer from the austenite direction towards the ferrite, accompanied by a reduced influence from the substrate. Despite the differences in composition, both the secondary phase and austenite demonstrated comparable plating rates, showing that electroless Ni plating on SDSS was primarily influenced by the substrate, a finding which was primarily confirmed through phase analysis. [ABSTRACT FROM AUTHOR]

With increasing demand for Li-ion batteries, studies are focusing on enhancing battery performance and safety. However, studies on battery cases remain scarce. Herein, we propose the use of super duplex stainless steel SAF2507, which is a two-phase (austenite + ferrite) steel, for battery casings. Unlike conventional AISI304, SAF2507 maintains its corrosion resistance and strength at high temperatures and precipitates a secondary phase at approximately 975 °C. However, the effects of Ni plating on this secondary phase are not well documented. Therefore, the electroless Ni plating of SAF2507 after secondary-phase precipitation was studied. Briefly, heat treatment at 1000 °C was used to induce precipitation, and the electroless Ni plating behaviour over varying plating periods was analysed using open-circuit potential, potentiodynamic polarisation, and electrochemical impedance spectroscopy measurements. The plating state and corrosion behaviour were examined using scanning electron microscopy. Heat-treated SAF2507 steel with a secondary phase exhibited excellent electroless Ni plating behaviour, which enhances the safety and durability of Li-ion batteries. Furthermore, uniform plating and electrochemical behaviour were achieved after 180 s, suggesting that SAF2507 is superior to AISI304. These findings contribute to the development of safer and more efficient batteries and address the growing demand for Li-ion battery case materials. [ABSTRACT FROM AUTHOR]

Carbon steel is subjected to several pretreatments to enable its use in highly corrosive environments, such as marine structures. However, its surface treatment is problematic owing to various processes, and these problems can be solved by replacing it with super duplex stainless steel (SDSS), which exhibits remarkable strength and corrosion resistance owing to its austenite and ferrite phases. EN 1.4410 and EN 1.4501 are the most extensively used SDSS grades in marine structures, as they exhibit exceptional strength and corrosion resistance in seawater. This study subjected EN 1.4410 and EN 1.4501 samples to specific heat treatment after casting and observed their structural alterations through field emission scanning electron microscopy. Their passivation states, with or without the Cu and W layers, were determined by examining their corrosion properties through open-circuit potential measurements, electrostatic polarisation tests, electrochemical impedance spectroscopy (EIS), and critical pitting temperature (CPT) analysis. The inclusion of Cu significantly improved the uniform corrosion resistance within the passivation layers, whereas the addition of W enhanced the pitting resistance (Epit, CPT). Additionally, the EIS analysis confirmed a double-layer structure in the passivation layer of EN 1.4501. Moreover, Cu did not act as a strengthening element of the passivation layer, whereas W significantly reinforced it. [ABSTRACT FROM AUTHOR]

Electroanalytical and optical techniques are widely used in the development of nanomaterials-based sensor platforms. These techniques have a quick response, high sensitivity, and selectivity. Electroanalytical and optical techniques are widely used in the development of nanomaterial-based sensor platforms. These sensors must be able to detect biomarkers, pathogens, toxins, and pharmaceuticals in biological matrices associated with cardiovascular disease, cancer, and neurodegenerative diseases. Considering these pathophysiologies, numerous investigations have been undertaken to develop sensors for early diagnosis and treatment, utilizing nanomaterials such as quantum dots. Graphene quantum dots (GQDs), which are ideally nanometer-sized graphene fragments, have recently received increased attention due to their excellent physicochemical properties such as fast electron mobility, photostability, water solubility, biocompatibility, high specific surface area, and nontoxicity. Apart from the properties mentioned above, GQDs provide π–π interactions, electrostatic, and covalent interactions with an analyte, and ease of synthesis as well as the ability to combine with other nanomaterials, which have enabled their use in various sensing platforms. This review summarizes recent advances in GQDs-based nanocomposites for sensor applications, with a focus on electroanalytical and optical techniques, as well as current challenges and future prospects. [ABSTRACT FROM AUTHOR]

A water sensor for a nonaqueous solvent was fabricated using poly(1,5-diaminonapthalene (DAN) nanofibers, which were prepared through a catalytic chemical polymerization of the DAN monomer using Fe(III) salt as the catalyst. Poly(1,5-DAN) nanofibers were characterized by atomic force microscope (AFM), transmission electron microscope (TEM), scanning electron microscope (SEM), and UV-vis spectroscopy. The electrochemical properties of poly(1,5-DAN) nanofibers were investigated using cyclic voltammetry (CV). The electrochemical activity of poly(1,5-DAN) nanofibers was utilized for water sensing. The fabrication of water sensor was followed by placing one drop (about 2 [micro]L) of 0.01% poly(1,5-DAN) nanofibers solution in the gap between two split gold electrodes (PBSA) and completely dried. The response of the water sensor in an acetonitrile solution was evaluated under optimized conditions. The linear dynamic range was from 0.05 to 20%, and the detection limit was determined to be 0.01%. The response of this sensor was shown to be comparable to that obtained with the Karl Fischer titration method.

A novel and highly efficient methodology to regulate (enhance or suppress) the Volmer–Weber 3D growth mode of ultra‐thin (<10 nm) Ag layers by modulating the surface stoichiometry of ZnO substrates prior to Ag deposition is presented. Relative to pristine ZnO layers, oxygen‐deficient surface states formed by preferential removal of surface oxygen atoms remarkably improve Ag layer wettability, whereas oxygen‐excessive surface states formed by oxygen atom incorporation strongly facilitate Ag agglomeration. The dissimilar nucleation and coalescence dynamics are elucidated via combined molecular dynamics and force‐bias Monte Carlo simulations. The improved wettability results in significantly lower sheet resistance in the ultra‐thin (6–10 nm) Ag layers, for example, 6.03 Ωsq−1 at 8 nm, than the previously reported values from numerous other approaches in the equal thickness range. When this unique methodology is applied to ZnO/Ag/ZnO transparent electrodes, simultaneous improvement in electrical conductivity and visible transparency is realized, with a resultant Haacke figure of merit value of 0.139 Ω−1 that is >50% higher than the best reported value for an identically structured electrode. We select transparent heating devices as a model system to confirm that the superior optoelectronic properties are highly sustainable under simultaneous and severe electrical, mechanical, and thermal stresses. [ABSTRACT FROM AUTHOR]

The O and N gas ions (O3+, O+, N2+, and N4+) were implanted on the glassy carbon surface employing the electron cyclotron resonance ion source, which were characterized using electrochemical and surface analysis methods. The modified electrode was examined for the catalytic oxidation of bioorganic molecules including dopamine, where the O+ ion implanted GC revealed the best catalytic performance. The XPS and Raman results represented that the ion implantation made enrichment in graphite nanocrystalline structure with edge plane, showing the enhanced electrochemical activity. It showed excellent performance for dopamine detection without significant interferences between 50.0 nM and 400.0 μM with the detection limit of 10.0±2.5 nM (95 % confidence level). The reliability of proposed electrode was evaluated by the real urine sample analysis. [ABSTRACT FROM AUTHOR]

We report an optimized multi-step chemical vapor deposition process for growing MoS2 thin films. This process enables large-area processing, film patterning simply by using shadow masks, and precise control of the final thickness by changing the initial thickness of the first step of MoO3 film deposition. The structural characterization of the MoS2 films is performed with transmission electron microscopy and X-ray diffraction as a function of film thickness. MoS2 film with a thickness of 3 nm possesses a highly crystalline structure with a spacing of 0.62 nm. The crystallinity and orientation of the films are degraded with increased film thickness. Careful analysis by time-of-flight secondary ion mass spectroscopy reveals that a film with a thickness of 9 nm is not completely sulfurized, and unreacted MoO3 is left at the bottom of the film. These fundamental analyses coincide with the thickness dependence of thin-film transistor (TFT) performance. A TFT with the optimal film thickness of 3 nm achieves high performance, namely a carrier mobility of 0.57 cm2 V−1 s−1 and an on/off ratio of ~ 102. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen-incorporated amorphous In–Sn–O (a-ITO) thin films were fabricated by introducing hydrogen gas during deposition. The hydrogen concentration in the thin films was experimentally determined to vary from 4.7 × 1020 to 8.1 × 1020 cm−3 with increasing H 2 flow rate. The mechanical stability of the a-ITO thin films dramatically improved with the optimal amount of hydrogen (~5.3× 1020 cm−3), without any observable degradation in electrical or optical properties. With increasing hydrogen concentration to the optimal value, the compressive residual stress gradually decreased and the subgap absorption at ~3.1 eV was suppressed. Considering that the residual stress and subgap absorption mainly originate from defects, hydrogen may be a promising candidate for defect passivation in flexible electronics. Highlights • Hydrogen-incorporated amorphous In−Sn − O thin films were fabricated. • Bending stability of films dramatically improved by hydrogen incorporation. • Subgap states was suppressed by optimal amount of hydrogen. [ABSTRACT FROM AUTHOR]

A new approach based on differential pulse voltammetry (DPV) was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using a modified glassy carbon electrode (GCE). The sensor was constructed by a simple “one-step” technique, wherein de-bundled single-walled carbon nanotubes (SWCNTs) were drop-cast onto the GCE. Without de-bundling, the SWCNTs were poorly dispersed in aqueous solution and were ineffective for the one-step procedure. De-bundling of the SWCNTs was achieved using a small amount (0.1 wt%) of the synthesized polymer dispersant, sulfonated poly(ether sulfone) (SPES); the de-bundled SWCNTs had a high aspect ratio (length = 2.5 ± 1.0 μm; height = 2 ± 1 nm, as determined using transmission electron microscopy and atomic force microscopy). The de-bundled SWCNTs also led to enhanced electrocatalytic activity and selectivity of the modified sensor for the simultaneous determination of AA, DA, and UA in DPV measurements: the peak-to-peak separation values were 221, 119, and 340 mV (vs. Ag/AgCl) for DA–AA, UA–DA, and AA–UA, respectively. The dynamic linear ranges for AA, DA, and UA were 0.2–1.6 mM, 5.0–50 μM, and 5.0–60 μM, and the detection limits were 10.6 μM, 15 nM, and 113 nM (S/N = 3), respectively. The analytical performance of the developed sensor was demonstrated in the determination of AA and DA in commercial pharmaceutical samples (vitamin C tablets and DA injection). The characteristics of the modified sensor make it promising for the individual or simultaneous determination of AA, DA, and UA. [ABSTRACT FROM AUTHOR]

A long-life electrochemical sensor for the continuous analysis of heavy metal ions (Zn(II), Cd(II), Pb(II), Cu(II), and Hg(II)) was developed using the graphene oxide (GO) anchored-functionalized polyterthiophene (poly[3′-(2-aminopyrimidyl)-2,2′:5′,2′′-terthiophene], polyPATT) composite. The PATT monomer was synthesized and polymerized with GO to form the composite using a potential cycling method, followed by Nafion coating. The modified sensor surface was characterized employing electrochemical and surface analysis methods. Experimental variables affecting the analytical performance were optimized. Interference effects of other metal ions having similar redox potentials were also investigated. The performance of chronocoulometry (CC) without predeposition was compared with the results of square wave anodic stripping voltammetry (SWASV) with predeposition. The dynamic range of CC for the target ions were between 1 ppb and 10 ppm, respectively with the detection limits between 0.05 (±0.05) and 0.20 (±0.15) ppb for the CC method without predeposition, and between 0.08 (±0.05) and 0.30 (±0.12) ppb for the SWASV with 300 sec of deposition time ( n=3). The reliability of the method was evaluated by continuously analysing environmental water samples using a single sensor probe in a flow system for 93 days. [ABSTRACT FROM AUTHOR]

A novel aptamer-based amperometric nanobiosensor was designed for the sensitive and selective detection of A549 human non-small-cell lung cancer (NSCLC) cells. The cytosensing was performed using a MUC1 aptamer probe with a bioconjugate, where the probe was fabricated by the covalent immobilization on a conducting polymer nanocomposite formed through the self-assembly of 4-([2,2':5',2''-terthiophen]-3'-yl) benzoic acid (TTBA) on AuNPs. A bioconjugate composed of hydrazine and aptamer attached on AuNPs was used to reveal the selectively amplified detection signal. The cells were quantitatively analyzed using chronoamperometric measurements, and the results were further compared and confirmed using microscopic and DPV methods based on silver staining cytosensing experiments. The proposed aptasensor showed a high affinity for MUC1 positive lung cancer cells (A549) compared with the other control cancer cells, including human prostate (PC3), MUC1 negative normal lung (MRC-5), and liver tumors (HepG2) cells. An excellent dynamic range of the proposed method was obtained from 15 to 1×10 6 cells/mL with a detection limit of 8 cells/mL. [ABSTRACT FROM AUTHOR]

A recent study on nanoporous carbon based materials ( J. Am. Chem. Soc.­ 2012, 134, 2864) showed that the presence of abundant graphitized sp2 carbon species in the frameworks led to higher affinity for aromatic hydrocarbons than their aliphatic analogues. Herein, improved understanding of the sensitive and selective detection of aromatic substances by using mesoporous carbon (MPC)-based materials, combined with a quartz crystal microbalance (QCM) sensor system, was obtained. MPCs were synthesized by direct carbonization of mesoporous polymers prepared from resol through a soft templating approach with Pluronic F127. The carbon-based frameworks can be graphitized through the addition of a cobalt source to the precursor solution, according to the catalytic activity of the cobalt nanoparticles formed during the carbonization process. From the Raman data, the degree of the graphitization was clearly increased by increasing the cobalt content and elevating the carbonization temperature. From a QCM study, it was proved that the highly graphitized MPCs exhibited a higher affinity for aromatic hydrocarbons than their aliphatic analogues. By increasing the degree of graphitization in the carbon-based pore walls, the MPCs showed both larger adsorption uptake and faster sensor response towards toxic benzene and toluene vapors. [ABSTRACT FROM AUTHOR]

A Cu(II)-Poly(terthiophene carboxylic acid) (pTTC)/Nafion modified glassy carbon electrode has been used for the chiral recognition and discrimination of d- and l-prolines by the catalytic oxygen reduction process and the shape of crystals formed on the electrode surface. The cyclic voltammetry with the modified electrode in the presence of oxygen recognized d- and l-form of prolines by exhibiting a difference in the peak potential and the peak current of the oxygen reduction. The effect of pH and proline concentration on the peak current and the peak potential of oxygen have been studied. The SEM studies on the nature of crystals formed on a proline-Cu(II)pTTC complex. The oxidation state of the copper species present at the electrode surface was characterized by ESCA. [ABSTRACT FROM AUTHOR]