Ambient Degradation Research Articles

Direct Recycling of LixNi0.5Mn0.3Co0.2O2 from Production Scrap and End‐Of‐Life Batteries, Using Solid‐State Relithiation

AbstractDirect recycling of Li‐ion battery cathodes offers a sustainable and potentially cost‐effective alternative to conventional methods, often involving complex chemical processes and significant material losses. This study focuses on the relithiation of cathode materials from quality control reject (QCR) and end‐of‐life (EoL) Li‐ion cells to restore their physical structure, morphology, and electrochemical performance. Two NMC532/graphite pouch cells from the same manufacturer were studied. QCR cells, stored under ambient conditions, experienced corrosion and degradation before recycling, while EoL cells were cycled to the end of life. The cells were disassembled, and the cathode materials were delaminated using NaOH solution, then relithiated with LiOH at 700 °C for 15 hours in the air. Extensive characterization analyzed elemental composition, structural properties, thermal stability, and particle size distribution. Results indicated that relithiation successfully restored lithium content and improved the structural ordering and morphology of the cathode materials. The electrochemical performance of the relithiated cathodes exhibited good stability over 100 charge‐discharge cycles. The relithiated QCR samples achieved a capacity of 155.57 mAh g−1, while EoL samples reached 152.53 mAh g−1, comparable to pristine materials. This study highlights relithiation's potential to extend the lifecycle of Li‐ion cathodes, contributing to a more sustainable circular economy for battery materials.

Impact of ambient moisture on gate controllability in ferroelectric-gate field-effect transistors with bottom-gate geometry

Ferroelectric-gate field-effect transistors (FeFETs) with a bottom-gate geometry consisting of a ferroelectric HfO2 gate and an oxide channel have been intensively studied in recent years. However, there has been no detailed investigation into the impact of atmospheric exposure on device performance, even though the channel is often exposed to ambient air for process simplification, especially at the research stage. In this study, the ambient stability of an indium tin oxide channel FeFET with a ferroelectric Ce-HfO2 bottom gate was investigated. We found that ambient degradation of the gate controllability was caused by an increase in physisorbed water in the device owing to the intrusion of moisture. Mobile ions, such as H+, which can easily move through a network of hydrogen bonds formed by adjacent physisorbed water, may compensate for ferroelectric polarization. Finally, we demonstrated that the observed degradation can be managed effectively without compromising the original device characteristics using Al2O3 passivation gently formed via plasma-free deposition.

Estimation of battery temperature during drive cycle operation by the time evolution of voltage and current

During the operation of electric vehicles, accurate temperature monitoring of lithium-ion batteries by battery management system is crucial to their safety. However, temperature sensors possess limitations as they necessitate regular calibration to avoid inaccuracies, which can be challenging to accomplish in certain scenarios. As an alternative, a general sensorless temperature estimation framework is developed in this study to either serve as a complementary approach alongside sensors or function independently to ensure reliable temperature measurement. The proposed framework relies solely on data regarding battery voltage and current measurements, and this information is employed to determine the parameters of the equivalent circuit model via the vector-type recursive least squares algorithm in the first step. In the second step, these parameters and the voltage/current data serve as the input to the deep neural network (DNN) to estimate the instantaneous battery surface temperature during dynamic driving cycles under various ambient temperatures and degradation scenarios. To reflect the effect of past battery operation on the current temperature, a newly defined current integral function is proposed, by which the input time length of the DNN model is suggested. Four combinations of the model input are studied, and the best input option yields an average estimation error of the battery temperature that falls below 0.5 °C.

Minimizing defect states through multidentate coordination and morphology regulation for enhancing the performance of inverted perovskite solar cells.

The diversity of the defects present in perovskite materials negatively impacts both the power conversion efficiency (PCE) and the long-term stability of perovskite solar cells (PSCs). The chemical passivation of these defects has been addressed through a multifunctional molecule, 4-((trifluoromethyl)thio)benzoic acid, that contains the carbonyl (CO) group, which exhibits a strong passivation effect by interacting with both the organic cation (FA+) and uncoordinated Pb2+ ionic defects while the sulfur (S) heteroatom passivates Pb2+ defects at the grain boundary and on the surfaces of the perovskite layer. Additionally, the CF3 group protects the perovskite film from ambient degradation as well as stabilizing the perovskite framework by forming hydrogen and coordination bonds with the FA+ cation and Pb2+ ions, respectively. The interaction between CO and Pb2+ forms a Lewis acid-base adduct that regulates grain growth during crystallization, enhancing the perovskite film's surface morphology as confirmed by SEM, AFM, and PL mapping. This reduces trap-assisted recombination of charged carriers, thereby enhancing their lifetime and transport, as observed from TRPL, KPFM, and c-AFM analyses. As a result of the combined effect of the additive molecule, the optimized device showed a marked improvement in efficiency rising from 16.54% in the pristine device to 20.87% with a reduction in hysteresis. Moreover, the optimized device shows enhancement of stability by retaining ∼86% normalized PCE after 40 days of storage under ambient conditions at 25 ± 3 °C and a relative humidity of ∼45-55%.

Tailoring microstructural features of Cr3C2-25NiCr coatings through diverse spray variants and understanding the high-temperature erosion behavior

Thermal sprayed Cr3C2-NiCr coatings are widely used to protect industrial components from ambient or elevated erosive degradation. Various thermal spraying techniques such as plasma spray, detonation spray (DS), high velocity oxy-fuel (HVOF) and high velocity air-fuel spray (HVAF) are widely used to deposit Cr3C2-NiCr coatings. The choice of thermal spraying technique governs the inflight particle velocity and temperature, resulting in unique coating microstructural features, characteristics and erosion performance. In this study, Cr3C2-NiCr coatings are deposited through HVAF, DS and axial plasma spray. A comprehensive comparative analysis was performed to understand the process-structure-property relationship of Cr3C2-NiCr coatings, which correlated with the room and high temperature erosion performance. HVAF spray deposited Cr3C2-NiCr coatings with preferred microstructural features and properties, ensuring superior (high/room temperature) erosive resistance. Cr3C2-NiCr coatings deposited via DS spray performed second best, while plasma sprayed exhibited defective microstructure with inferior mechanical properties, resulting in substandard erosion performance.

Resistive switching characteristics of methyl-ammonium lead iodide perovskite during atmosphere degradation

Methylammonium lead iodide (MAPbI3) with extraordinary optoelectronic properties has recently been explored for memristors. Despite significant studies on its susceptibility to air, there has been limited attention towards the impact of ambiance on resistive switching (RS), specifically, the nanoscale electrical properties of interest. We used scanning probe microscopy (SPM) to study local current-voltage (I-V) characteristics, time-scale evolution of hysteresis, current maps, and topography to profoundly understand the ambient degradation. The local and macroscopic current-voltage characteristics are studied by interface modulation with (3-Aminopropyl)trimethoxysilane (APTMS) in devices, i.e., ITO/APTMS/MAPbI3 and ITO/ MAPbI3/APTMS. We report three stages of degradation based on quantitative nano-mechanical (QNM) characterizations and local I-V properties: stage 1 comprising of increased Young’s modulus accompanied by the appearance of hysteresis; stage 2 with decreased Young’s modulus when RS and negative differential resistance (NDR) happen with the evolution of lead iodide (PbI2); stage 3 when RS disappears with enhanced Young’s modulus and densification of PbI2. The enhanced nanoscale and macroscale RS characteristics of ITO/MAPBI3 and ITO/APTMS/MAPbI3 could be attributed to the humidity-induced degradation of MAPbI3 into PbI2 indicated by XRD. These characteristics at the nanoscale however diminish on Day 7 showing the nano-scale RS devices requires the prompt attention of researchers.

Enabling Ambient Stability of LiNiO2 Lithium-Ion Battery Cathode Materials via Graphene–Cellulose Composite Coatings

Nickel-rich layered oxides are widely used as cathode materials for energy-dense lithium-ion batteries. These chemistries, based on the parent compound LiNiO2 (LNO), are highly sensitive to ambient environments and are known to readily react with moisture and carbon dioxide. As a result, impurities such as lithium hydroxides and lithium carbonates are formed at the LNO surface, compromising electrochemical behavior. Here, we address this issue by coating LNO cathode particles with a hydrophobic barrier layer composed of graphene and ethyl cellulose (GrEC). This coating limits contact between atmospheric moisture and the LNO surface, which minimizes the generation of lithium impurities. This scheme is evaluated by exposing coated LNO to humidified CO2 for 24 h as an accelerated ambient degradation test. Subsequent spectroscopy, microscopy, and electrochemical characterization show no detectable signatures of carbonates on the LNO surface, thus verifying that the GrEC coating prevents ambient degradation. By demonstrating this methodology for the ultimate nickel-rich chemistry, this approach can likely be generalized to a wide range of ambient-sensitive battery materials.

Amino Acid-Based Polyphosphorodiamidates with Hydrolytically Labile Bonds for Degradation-Tuned Photopolymers.

Photochemical additive manufacturing technologies can produce complex geometries in short production times and thus have considerable potential as a tool to fabricate medical devices such as individualized patient-specific implants, prosthetics and tissue engineering scaffolds. However, most photopolymer resins degrade only slowly under the mild conditions required for many biomedical applications. Herein we report a novel platform consisting of amino acid-based polyphosphorodiamidate (APdA) monomers with hydrolytically cleavable bonds. The substituent on the α-amino acid can be used as a handle for facile control of hydrolysis rates of the monomers into their endogenous components, namely phosphate and the corresponding amino acid. Furthermore, monomer hydrolysis is considerably accelerated at lower pH values. The monomers underwent thiol-yne photopolymerization and could be 3D structured via multiphoton lithography. Copolymerization with commonly used hydrophobic thiols demonstrates not only their ability to regulate the ambient degradation rate of thiol-yne polyester photopolymer resins, but also desirable surface erosion behavior. Such degradation profiles, in the appropriate time frames, in suitably mild conditions, combined with their low cytotoxicity and 3D printability, render these novel photomonomers of significant interest for a wide range of biomaterial applications.

Topotactic, Vapor-Phase, In Situ Monitored Formation of Ultrathin, Phase-Pure 2D-on-3D Halide Perovskite Surfaces.

Two-dimensional (2D) halide perovskites, HaPs, can provide chemical stability to three-dimensional (3D) HaP surfaces, protecting them from exposure to ambient species and from reacting with contacting layers. Both actions occur with 2D HaPs, with the general stoichiometry R2PbI4 (R: long or bulky organic amine) covering the 3D ones. Adding such covering films can also boost power conversion efficiencies of photovoltaic cells by passivating surface/interface trap states. For maximum benefit, we need conformal ultrathin and phase-pure (n = 1) 2D layers to enable efficient tunneling of photogenerated charge carriers through the 2D film barrier. Conformal coverage of ultrathin (<10 nm) R2PbI4 layers on 3D perovskites is challenging with spin coating; even more so is its upscaling for larger-area devices. We report on vapor-phase cation exchange of the 3D surface with the R2PbI4 molecules and real-time in situ growth monitoring by photoluminescence (PL) to determine limits for forming ultrathin 2D layers. We characterize the 2D growth stages, following the changing PL intensity-time profiles, by combining structural, optical, morphological, and compositional characterizations. Moreover, from quantitative X-ray photoelectron spectroscopy (XPS) analysis on 2D/3D bilayer films, we estimate the smallest width of a 2D cover that we can grow to be <5 nm, roughly the limit for efficient tunneling through a (semi)conjugated organic barrier. We also find that, besides protecting the 3D against ambient humidity-induced degradation, the ultrathin 2D-on-3D film also aids self-repair following photodamage.

Passivating violet phosphorus against ambient degradation for highly sensitive and long-term stable optoelectronic devices

Recent success in exfoliating violet or Hittorf's phosphorus down to monolayer reignites the research passion in this ancient yet mysterious material, questing for superior electronic and optoelectronic functionalities. Unfortunately, the poor air stability that plagues black phosphorus also exists in the violet counterpart. Aiming to provide more insight into the degradation chemistry and accordingly find a facile solution for it, herein, we employ concerted elemental, chemical and vibrational spectroscopies to reveal the critical role of oxygen and water in the degradation mechanism and pathway of violet phosphorus in ambient condition. Thereafter, a simple passivation approach by oxide encapsulation is demonstrated to realize air-stable violet phosphorus photodetector device. As the proof-of-concept, the photodetector fabricated accordingly shows superior figures of merit with ultralow dark current (&amp;lt; 10−13 A), high low-light responsivity (6 A W−1) and fast response time (&amp;lt; 10 ms) in the ultraviolet to visible spectrum, as well as great chemical robustness against harsh environments.

Thermocatalytic Performance of LaCo1−xNixO3−δ Perovskites in the Degradation of Rhodamine B

Perovskite-type LaCo1−xNixO3−δ (x = 0, 0.2, 0.4, 0.6, and 0.8) powders were synthesized by solution combustion synthesis. The crystal structure, morphology, texture, and surface were characterized by X-ray powder diffraction combined with Rietveld refinement, scanning electron microscopy, N2-adsorption, X-ray photoelectron spectroscopy, and zeta-potential analysis. The thermocatalytic properties of the perovskites were investigated by UV–Vis spectroscopy through degradation of rhodamine B in the temperature range 25–60 °C. For the first time, this perovskite system was proven to catalyze the degradation of a water pollutant, as the degradation of rhodamine B occurred within 60 min at 25 °C. It was found that undoped LaCoO3−δ is the fastest to degrade rhodamine B, despite exhibiting the largest energy band gap (1.90 eV) and very small surface area (3.31 m2 g−1). Among the Ni-doped samples, the catalytic performance is balanced between two main contrasting factors, the positive effect of the increase in the surface area (maximum of 12.87 m2 g−1 for 80 mol% Ni) and the negative effect of the Co(III) stabilization in the structure (78% in LaCoO3 and 89–90% in the Ni-containing ones). Thus, the Co(II)/Co(III) redox couple is the key parameter in the dark ambient degradation of rhodamine B using cobaltite perovskites.

Disentangling Source Profiles and Time Trends of Halogenated Flame Retardants in the Great Lakes.

Thirty-five polybrominated diphenyl ethers (PBDEs) and eight other alternative flame retardants were measured in air samples (vapor plus particles) collected at six sites near the North American Great Lakes between 2005 and 2019 as part of the Integrated Atmospheric Deposition Network (IADN). These data were analyzed using a multiple linear regression model to determine spatial and temporal trends. Overall, the levels of flame retardants remain significantly higher in urban sites compared to rural and remote sites except for pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), and total Dechlorane Plus (ΣDP). Here, we report the first findings of decreasing levels of ΣDP at Sturgeon Point, New York. The atmospheric levels of total PBDEs remain unchanged over time near Lakes Michigan and Superior and declined near Lakes Erie and Ontario, with rate constants at the latter two lakes revealing halving times of approximately 7 to 14 years. This work presents results from the first investigation of PBDE source apportionment in the Great Lakes atmosphere. Source apportionment by use of positive matrix factorization (PMF) identified two legacy commercial technical mixtures (i.e., penta-BDE and deca-BDE mixes) and elucidated a factor representing ambient degradation. Our results show that weathered local sources of technical commercial mixtures, and their photolysis contribute most to the total PBDE burden in the Great Lakes atmosphere.

Influences of the ambient temperature, degradation effect and usage habits over the energy consumption of domestic refrigerators in Brazil

Considering the relevance of the consumption of domestic refrigerators in the Brazilian residential sector, representing about 30% of the sectorial consumption, studies of factors that influence this consumption, such as ambient temperature, age of equipment and usage habits, are of great importance to a greater understanding of these effects and, thus, to promote better energy strategies for the country. In this sense, the present study evaluates the impacts of ambient temperature, age of the equipment and habits of use in the consumption of domestic refrigerators, based on theoretical models and laboratory tests. The laboratories assays, adhering to theoretical models, showed that the environment temperature can influence the consumption of refrigerators up to 50% less (taking into account the south region temperature), when comparing to the value that are labeled by PBE/INMETRO. When the usage habits are assayed, it was verified that the consumption of the refrigerator could be increased in up to 53%, depending the frequency of door opening.

Degradation Analysis of Triple-Cation Perovskite Solar Cells by Electrochemical Impedance Spectroscopy

In this work, the electrical properties of different triple-cation compositions with the formula Cs0.05FA1–XMAXPb(I1–XBrX)3 have been analyzed using electrochemical impedance spectroscopy. The perovskite solar cells were subjected to ambient conditions to compare their results in terms of ambient degradation. Their morphology, optical properties, and photovoltaic performance were characterized. We analyzed the causes and effects of ambient degradation mechanisms on the devices. Electrochemical processes such as ion movement, a combination of radiative recombination and nonradiative recombination, and charge transport were detected. The MA percentage decrease in the composition of triple-cation perovskites, APbX3 produces an improvement in the stability and durability of perovskite solar cells. This enhancement is due to the reduction of the amount of ion vacancies helping to reduce the degradation in the device by avoiding the accumulation of defects.

Excellent flame retardancy and air stability through surface coordination of few‐layer black phosphorus with TiL4 in epoxy resin

AbstractBlack phosphorus (BP) has been attractive for many research groups as its promising properties. However, the poor air stability of BP has limited its practical applications. To simultaneously address this problem and improve the flame retardancy of BP in epoxy resin (EP), a surface coordination strategy was proposed. Herein, a titanium ligand (denoted as TiL4) was designed to coordinate BP nanosheets, which can occupy the lone pair electrons of BP. The Ti–P coordination contributed to the improvement of ambient stability of BP. The serious degradation was observed from pure BP owing to the oxidation. Whereas, the surface coordination can impede the ambient degradation rate of BP by 74.07%. With the addition of 1.5 wt% TiL4@BP, the char yield of EP nanocomposites was increased by 20.55% due to the catalytic charring effect of TiL4@BP. The incorporation of 1.5 wt% TiL4@BP can reduce the peak of heat release rate and total heat release values of EP by 29.41% and 23.32%. The EP/TiL4@BP 1.5 also can pass the UL‐94 V‐0 rating, and its value of limiting oxygen index was enhanced by 13.60%. The improvement in the flame retardancy of BP in EP can be largely ascribed to synergistic catalytic charring effects between BP and TiL4. The condense and compact char layer can act as a physical barrier to restrict the exchange of pyrolytic products and the transfer of heat. In addition, the free radical quenching effect of BP nanosheets also accounted for the excellent flame retardant performance of EP. This work proposed a reference for synchronically obtaining the improvement for the air stability and flame retardant performance of BP.

Role of Channel Inversion in Ambient Degradation of Phosphorene FETs

Role of Channel Inversion in Ambient Degradation of Phosphorene FETs

Reversible Degradation in Hole Transport Layer‐Free Carbon‐Based Perovskite Solar Cells

The rationale for ambient degradation behaviors in hole transport layer (HTL)‐free carbon‐based perovskite solar cells (PSCs) still remains a mystery, although carbon‐based PSCs have been the frontrunner among the emerging next‐generation photovoltaics owing to their low cost of materials and fabrication process, as well as the exceptional durability. Herein, the long‐term stability of HTL‐free carbon‐based PSCs (H‐C‐PSCs) in the ambient air environment is investigated to thoroughly understand and identify the governing chemistry during the degradation. Specifically, a reversible degradation phenomenon is observed along with an anomalous S‐shape of current–voltage curves involving only reduction of fill factor (FF), almost without impact for short‐circuit current density and open‐circuit voltage. Furthermore, a minute‐heating treatment will eliminate the reversible degradation which can be attributed to the reversible formation of intermediate hydrate at the interface between perovskite and carbon contact. This provides a new perspective for the stability issue of H‐C‐PSCs.

A Novel Integrated Control Method for an Aero-Derivative Gas Turbine of Power Generation

On account of the complexity of aero-derivative gas turbines and the much higher control requirements, it is significant and meaningful to design advanced controllers for obtaining the ideal control effect. In this paper, to improve the performance of the original controller of an aero-derivative gas turbine, a novel integrated control method is proposed by combining the original controller with a new neural network controller. It realizes the speed control by switching the two controllers during the operation process of the aero-derivative gas turbine. A tracking test and robustness test are conducted to assess the superiority of the novel integrated control method. The results show that in comparison with the original controller and the new neural network controller, the novel integrated control method has a much better speed tracking performance during the four tracking tests. When the model of the aero-derivative gas turbine changes with the ambient temperature and compressor performance degradation, the robustness of the novel integrated control method is also better than the other two controllers. Hence, the superiority of the novel integrated control method is validated.

Urban Land uses as Catalysts to Ambient Air Quality Degradation in the Metropolitan City of Calabar, Nigeria

This study examined urban landuses as catalysts to ambient air quality problems in Calabar metropolis, Nigeria. Data on emission level of CO, NO2, SO2, H2S, and SPM2.5 were acquired using Gasman, while point coordinates were collected using Garmin GPSMap 60CSx device. Student’s ttest statistics and Analysis of Variance (ANOVA) were employed to test the hypothesis. From findings, the null hypothesis was rejected for all the test parameters (CO, NO2, SO2, H2S, and SPM2.5) because it could not be concluded that the concentration of parameters measured were higher than the FEPA permissible limits for all the parameters. In order to help identify which ones were significantly higher or lower, the column of mean difference and t-value, where the mean difference is on the negative was consulted. This means that the concentration of the parameters in the air was within the FEPA permissible limits. Where that is the case, the calculated t-value is also negative. It should be noted that automated calculation of student’s t-statistics with the SPSS does not make use of the modulus sign. The use of modulus ignores the sign in statistical analysis. For this present student, the result for CO and H2S are within the acceptable limits while those for NO2, SO2 and SPM2.5 are higher than the acceptable limits. It was therefore recommended that there should be protection of the residential land uses to avoid encroachment by incompatible uses which cause pollution. Finally, green areas should be protected due to their potentials as urban green lungs.

Photo-Oxidation of Therapeutic Protein Formulations: From Radical Formation to Analytical Techniques.

UV and ambient light-induced modifications and related degradation of therapeutic proteins are observed during manufacturing and storage. Therefore, to ensure product quality, protein formulations need to be analyzed with respect to photo-degradation processes and eventually protected from light exposure. This task usually demands the application and combination of various analytical methods. This review addresses analytical aspects of investigating photo-oxidation products and related mediators such as reactive oxygen species generated via UV and ambient light with well-established and novel techniques.