Search

The degradation of an AlGaN‐based deep‐ultraviolet laser diode during operation is studied. A rapid increase in threshold current without any facet mirror damage under direct current stress below the threshold current is observed, which is considered to limit the lifetime of continuous wave lasing to the level of seconds. The evolution of current–light and current–voltage characteristics suggests that the dominant mechanism of degradation is the increased loss of carriers before they can reach the active layer, i.e., the decrease in carrier injection efficiency. The decrease in emission intensity, which is more pronounced at lower current densities, and subsequent increase in sub‐threshold current indicate the increase in defect density under current stress, which is similar to the well‐analyzed degradation mechanism found in AlGaN‐based light‐emitting diodes. [ABSTRACT FROM AUTHOR]

Micro‐/nanomotors (MNMs) in water remediation have garnered significant attention over the past two decades. More recently, metal‐organic framework‐based micro‐/nanomotors (MOF‐MNMs) have been applied for environmental remediation; however, a comprehensive summary of research in this research area is yet to be reported. Herein, a review is presented to cover the recent advances in MOF‐MNMs and their various applications in wastewater remediation. The review presents a comprehensive introduction to MNMs, including different propulsion approaches, fabrication, and functionalization strategies, in addition to the unique features of MOF‐MNMs. The conception and various synthetic routes of MOF‐MNMs are extensively covered and the implementation of MOF‐MNMs in water‐related applications, including adsorption, degradation, sensing, and disinfection of different pollutants, is in depth discussed. Meanwhile, the propulsion and mechanism of action behind each MOF‐MNM are systematically studied. Finally, the review provides insights into the challenges and perspectives to build more effective MOF‐MNMs to cover versatile applications for wastewater treatment. [ABSTRACT FROM AUTHOR]

As one of the five major engineering plastics, polyamide brings many benefits to humans in the fields of transportation, clothing, entertainment, health, and more. However, as the production of polyamide increases year by year, the pollution problems it causes are becoming increasingly severe. This article reviews the current recycling and treatment processes of polyamide, such as chemical, mechanical, and energy recovery, and degradation methods such as thermal oxidation, photooxidation, enzyme degradation, etc. Starting from the synthesis mechanism of polyamide, it discusses the advantages and disadvantages of different treatment methods of polyamide to obtain more environmentally friendly and economical treatment schemes. Finding enzymes that can degrade high-molecular-weight polyamides, exploring the recovery of polyamides under mild conditions, synthesizing environmentally degradable polyamides through copolymerization or molecular design, and finally preparing degradable bio-based polyamides may be the destination of polyamide. [ABSTRACT FROM AUTHOR]

The low nutritive value of pastures in tropical regions represents a limitation in the productivity of grazing ruminants. The objective was to determine the in vitro chemical and fermentative characteristics of nine tropical grasses (Aruana [Panicum maximun Jacq. cv. Aruana], Bermuda [Cynodon dactylon L.], Estrella de África [Cynodon Cynodon nlemfuensis Vanderyst], Insurgente [Brachiaria brizantha Hochst. Stapf.], Llanero [Andropogon gayanus Kunth], Mombaza [Panicum maximun Jacq. cv. Mombaza], Pará [Brachiaria mutica Stapf], Pangola [Digitaria eriantha Steud.], and Tanzania [Panicum maximun Jacq. cv. Tanzania]) at three regrowth ages (30, 45, and 60 days). The chemical analysis was used to determine the concentrations of dry matter (DM), crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and ash (Ce). The in vitro trial measured partial (24, 48, and 72 h) and cumulative biogas and methane production, fermentation kinetics estimators (A, b, and k), dry matter degradation (DMD) and detergent neutral fiber degradation (NDFD), pH, and ammonia nitrogen (N-NH3). The experimental design was completely randomized at each regrowth age. In conclusion, based on chemical analysis and fermentative characteristics, Pangola and Estrella pastures performed better at each regrowth age. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) is a well‐known and widely used commodity plastic. High production amount of PMMA causes excessive waste creation that highlights the necessity of recycling. Conventional recycling methods require elevated temperatures to induce degradation or depolymerization. In this work, visible light induced photodegradation system by using dimanganese decacarbonyl (Mn2(CO)10) with high halogen affinity is reported. Halide functional photodegradable polymers are prepared by copolymerization of methyl methacrylate and methyl α‐chloroacrylate by conventional reversible addition‐fragmentation chain‐transfer polymerization. Synthesized copolymers are efficiently degraded to low molecular weight oligomers under visible light irradiation in the presence of Mn2(CO)10. Characteristics of precursors, degraded polymers, and kinetics of depolymerization are investigated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourrier transform infrared (FTIR), and proton nuclear magnetic resonance (1H‐NMR) spectroscopies. The reported approach is expected to trigger further development of more environmentally friendly recycling techniques in the near future as we are moving toward a greener and more sustainable world. [ABSTRACT FROM AUTHOR]

Sequence‐defined and degradable polymers can mimic biopolymers, such as peptides and DNA, to undertake life‐supporting functions in a chemical way. The design and development of well‐structured oligomers/polymers is the most concern for the public, even to further uncover their degradation process illustrating the degraded products and their properties. However, seldom investigation has been reported on the aforementioned aspects. In this work, the alternating photo‐reversible addition‐fragmentation chain‐transfer (photo‐RAFT) single unit monomer insertion (SUMI) of different N‐substituted maleimides and thermal radical ring‐opening SUMI of a cyclic ketene acetal monomer (i.e., 5,6‐benzo‐2‐methylene‐1,3‐dioxepane (BMDO)) is adopted, to produce two degradable pentamers owing to the conversion of the exo‐methylene group of BMDO into ester bonds along the main chains of the prepared products. Moreover, the possible degraded approach of pentamers is studied by combining high‐resolution mass spectrometry (HRMS) and liquid chromatography‐mass spectrometry (LC‐MS) for the first time. This work also sheds light on the precise structures and cytotoxicity of SUMI products and their degraded compounds, proposing a detailed and credible outlook for biomedical applications. [ABSTRACT FROM AUTHOR]

The change in the morphological parameters of the minor bed takes place under the influence of natural and anthropogenic modelling factors. The minor river beds located in the urban areas are intensively affected by the presence of anthropogenic risk factors. The research carried out on the Bahlui River in the area of the city of Iasi highlighted important changes in the minor river bed determined by the regularization works carried out asymmetrically in the river bed. The presence of rainwater drains is an important anthropogenic factor of erosion of the minor bed. In this case, in the minor river bed, there is an important differentiation in the cross section between hydraulic parameters (maximum velocities, roughness, erosion force), a situation that leads to the intense erosion of the right bank. [ABSTRACT FROM AUTHOR]

Here, two B‐doped Cz‐grown Si materials with different Al concentrations are investigated concerning the long‐term behavior of excess charge carrier lifetime under injection at elevated temperature. By determining the defect density and the surface saturation current density, a delay in regeneration and a delay in the onset of surface‐related degradation is found in the material containing an order of magnitude more Al. Investigations under constant excess carrier concentration reveal that the effect of the delay is still significant, but less pronounced compared with constant generation conditions, so the effect causing the delay seems to be injection dependent. The findings can be explained by the higher activation energy for the splitting of Al−H pairs compared with splitting of B−H pairs, which might cause a delayed release in H from the dopant H configuration. Assuming that regeneration depends on this released H, the delay in regeneration can be explained by this model. [ABSTRACT FROM AUTHOR]

Ceramic solid electrolytes are crucial for electrochemical devices, including emerging solid-state batteries. However, they are susceptible to degradation and failure under harsh conditions, leading to dendrite growth, cracking and short circuits. While longitudinal lithium dendrites have been identified as a primary degradation mechanism, recent experiments have revealed transverse reduction fronts and bowl-shaped cracks that differ significantly from the longitudinal picture. We propose an electrochemical shock model to explain these transverse degradation modes in solid electrolytes (SE) and mixed ionic-electronic conductors (MIEC), where SE is taken to be the very weakly electronic leaking limit of MIEC. The model describes a transverse layer with an abrupt oxygen potential jump over a short distance, caused by the electronic transport bottleneck on the Brouwer diagram. Using Li 7 La 3 Zr 2 O 12 as an example, we demonstrate that even minor nonuniform lithium distribution associated with an electrochemical shock can induce stress concentrations, resulting in electrolyte cracking and bowl-shaped cracks. The electrochemical shock model highlights the significance of finite electronic conductivity in the degradation of SE and MIEC, providing insights for the design of durable solid electrolytes. [Display omitted] [ABSTRACT FROM AUTHOR]

The degradations of electrical parameters for silicon carbide power MOSFETs under repetitive short-circuit (SC) stress are investigated in detail in this paper. It demonstrates that the generation of negative charges along the gate–oxide interface of the channel region is the dominant degradation mechanism, which results in the increase in the threshold voltage (${V}_{\text {th}}$) and the rise of ON-state resistance (${R}_{\text {dson}}$) under low gate voltage bias condition. Furthermore, degradations of dynamic characteristics including gate charge (${Q}_{\text {g}}$) and switching behaviors of the device after the repetitive SC stress are extracted and analyzed for the first time. It illustrates that the increased ${V}_{\text {th}}$ contributes to the rise of the Miller plateau voltage (${V}_{\text {gp}}$), which further leads to the increase in gate–source charge (${Q}_{\text {gs}}$). Meanwhile, the increase in the turn-ON time and the reduction of turn-OFF time are observed, which are also resulted from the positive shifts of ${V}_{\text {th}}$ and ${V}_{\text {gp}}$ , leading to the rise of turn-ON switching energy (${E}_{{ \text {on}}}$) and the decline of turn-OFF switching energy (${E}_{\text {off}}$), respectively. [ABSTRACT FROM AUTHOR]

The built environment on the national territory is permanently affected by the lack of current maintenance work on buildings. This can have serious consequences on medium and long term. Often, the costs of ensuring a specialist for observation and current maintenance work are much lower than the cost of repair work due to lack of maintenance. This paper presents a series of degradations that are currently found on buildings, as well as some case studies of buildings with severe degradation caused by the lack of current maintenance work. [ABSTRACT FROM AUTHOR]

Novel tetranuclear vanadyl glycollates [Ni(phen) 3 ] 2 [V IV 4 O 4 (glyc) 6 ]·23H 2 O ( 1 ) and [Ni(phen) 3 ] 2 [V IV 4 O 4 (glyc) 6 ]·16H 2 O ( 2 ) have been obtained through the capture of bulky nickel phenanthroline cation (H 2 glyc = glycollic acid, phen = 1,10-phenanthroline), and the mixed-ligand complex [V IV 4 O 6 (glyc) 2 (bpy) 4 ]·6H 2 O ( 3 ) (bpy = 2,2′-bipyridine) was isolated with the addition of bpy under hydrothermal condition. Tetrameric 1 and 2 are easily oxidized to dimeric complex [Ni(phen) 3 ][V V 2 O 4 (glyc) 2 ]·5H 2 O ( 4 ), while 3 with bipyridine is stable. The degradation process was traced by IR and XRD experiment. 1 – 4 feature bidentate glycollate that chelates to vanadium atom through α-alkoxy and α-carboxy groups, which were full characterized by elemental analysis, TG, IR, UV–Vis, EPR, XRD and X-ray structural analyses. Bond valence calculation is also performed. [ABSTRACT FROM AUTHOR]

In this paper, the electrical parameter degradations of high-voltage 4H-SiC MOSFETs under repetitive unclamped-inductive-switching (UIS) stresses were investigated experimentally. The holes injection and trapping into the gate oxide above the JFET region is identified to be the main degradation mechanism, resulting in the increase of OFF-state drain–source leakage current ( I\mathrm {DSS}) and the decrease of ON-state resistance ( R\mathrm {dson}) . However, during the repetitive UIS stresses, there is not obvious degradation observed for the threshold voltage ( V\mathrm {th}) of the device. Moreover, three improved SiC MOSFETs structures, one with step gate oxide above the JFET region, one with step p-body region, and another one with floated shallow p-well in the middle of JFET region, were proposed to reduce the degradations under the repetitive UIS stresses. [ABSTRACT FROM AUTHOR]

In this paper, a Passive Fault Tolerant Control strategy dedicated to air feeding system fault based on an auto-tuning PID regulator is designed and implemented on a real fuel cell test bench. The present work compares the auto-tuning PID strategy performance to classical PID controller and highlights its benefits during faulty operation. Experimental results demonstrate the effectiveness of the proposed approach to regulate oxygen stoichiometry in real-time operation while maintaining a proper system performance under faulty situations. Unlike the classical PID controller, the proposed Passive Fault Tolerant Control System shows highly satisfactory performance in terms of setpoint tracking accuracy and disturbances rejection capability during faulty operations. [ABSTRACT FROM AUTHOR]

This paper is aimed at the assessment of the resistance to tracking of insulators made of several polymers, widely used in electrical industry (medium voltage cable accessories such as terminations and insulators and anchoring clamps and mechanical screw fuses), under polluted environments. This new method performed on one insulator model is based on the electro-geometrical characteristics (AC flashover voltage versus leakage distance). The tested materials cover thermoplastics, (namely polyamide 6 (PA6/50), fireproofed polyamide 66 (PA66/50), polycarbonate (PC/40) and polyarylamide (PARA/50)) thermosetting (namely two cycloaliphatic epoxy resins (EP1 and EP2)) and elastomers (namely two EPDM materials noted EPDM and EPDM V0 (fireproofed)). Polluted environments such as clean (light) and salt (heavy) fogs have been created to assess the resistance of polymers to partial discharges (erosion and tracking). Results regarding the flashover voltage (FOV) show a significant reduction in the presence of clean fog equal to 50% of the value measured in dry conditions for all polymers. This decrease is more pronounced in salt fog (-80% reduction of FOV). Surface degradations suggest that epoxy resins and EPDM elastomers are subjected to fewer damages in salt fog when being compared to thermoplastics. It is established that epoxy resins behave better than EPDM elastomers against discharges. In addition, polycarbonate (PC/40) exhibits the worst properties because of large tracking paths that form on its surface. [ABSTRACT FROM AUTHOR]

Ge is a candidate for replacing Si, especially for pMOSFETs, because of its high hole mobility. For Si-pMOSFETs, negative-bias temperature instabilities (NBTI) limit their lifetime. There is little information available for the NBTI of Ge-pMOSFETs with Ge/GeO2/Al2O3 stack. The objective of this paper is to provide this information and compare the NBTI of Ge- and Si-pMOSFETs. New findings include: 1) the time exponent varies with stress biases/field when measured by either the conventional slow dc or pulse I-V technique, making the conventional Vg -accelerated method for predicting the lifetime of Si-pMOSFETs inapplicable to Ge-pMOSFETs used in this paper; 2) the NBTI is dominated by positive charges (PCs) in dielectric, rather than generated interface states; 3) the PC in Ge/GeO2/Al2O3 can be fully annealed at 150 ^\circC ; and 4) the defect losses reported for Si sample were not observed. For the first time, we report that the PCs in oxides on Ge and Si behave differently, and to explain the difference, an energy-switching model is proposed for hole traps in Ge-MOSEFTs: their energy levels have a spread below the edge of valence band, i.e., Ev , when neutral, lift well above Ev after charging, and return below Ev following neutralization. [ABSTRACT FROM PUBLISHER]

Renewable energy sources and ways to store this energy due to its intermittency are growing exponentially. Redox flow batteries, which allow decoupling energy from power, are a promising way of electrochemical storage of electricity. Vanadium flow batteries, the current technological reference, are giving way to aqueous organic electroactive species, which present the advantages of multiple designs thanks to functionalization, lower cost, non-toxicity, and less supply issues. Their long-term performances are still compromised because of degradations of the electrodes, the membrane, or the organic species. Physical models are a good way to predict redox flow batteries behavior on long time scales and have a better understanding of the phenomena and their impact on the battery. Some degradations of the electrodes, the membrane or side reactions have been modelled, however very few models for organic active species degradations have been proposed yet. This review presents some reported degradations and their consequences for the cell components and organic electrolytes. Different existing models for aqueous organic redox flow batteries are presented, with a focus on Multiphysics models. Degradations' modelling in aqueous redox flow batteries is discussed, with existing degradations models as well as some proposals for future degradations modelling. • Aqueous organic flow batteries are promising for stationary energy storage. • Organic electrolytes are subject to many sources of degradations. • Multiphysics multiscale models are useful to describe batteries behavior. • Future work must focus on degradations modelling for flow batteries. [ABSTRACT FROM AUTHOR]

Abstract: Numerous Image Quality Measures (IQMs) have been proposed in the literature with different degrees of success. While some IQMs are more efficient for particular artifacts, they are inefficient for others. The researchers in this field agree that there is no universal IQM which can efficiently estimate image quality across all degradations. In this paper, we overcome this limitation by proposing a new approach based on a degradation classification scheme allowing the selection of the “most appropriate” IQM for each type of degradation. To achieve this, each degradation type is considered here as a particular class and the problem is then formulated as a pattern recognition task. The classification of different degradations is performed using simple Linear Discriminant Analysis (LDA). The proposed system is developed to cover a very large set of possible degradations commonly found in practical applications. The proposed method is evaluated in terms of recognition accuracy of degradation type and overall image quality assessment with excellent results compared to traditional approaches. An improvement of around 15% (in terms of correlation with subjective measures) is achieved across different databases. [Copyright &y& Elsevier]

Choosing the right battery for a given photovoltaic (PV) system is a key question, because it strongly influences the cost and reliability of the system. This paper presents results of seven test procedures experienced at the GENEC battery test facility. A set of four complementary tests is selected, covering the various types of photovoltaic systems. Moreover, the analysis of these results gives an estimation of the ageing rate for the different types of batteries used in photovoltaic systems. [Copyright &y& Elsevier]

• Detection of a potential unknown impurity under accelerated storage conditions. • Elucidated the structure of unknown impurity by LC–MS/MS, NMR (1D and 2D), HRMS and IR analysis. • Synthesized the degradation unknown impurity with high purity. • In-silico (Q) structure-activity relationships studies on this unknown impurity confirmed as non-mutagenic. • Validated the method by including degradation impurity and specified impurities of brimonidine tartrate. One potential unknown impurity was detected during the analysis of stability batches of brimonidine tartrate (BMT) in the level ranging from 0.03 % to 0.06 % by high-performance liquid chromatography (HPLC). Based on the liquid chromatography-mass spectrophotometry (LC–MS) analysis, the unknown impurity structure was presumed as 3,6,11,13,16-pentaazatetracyclo [8.6.0.0²,⁷.0¹²,¹⁶] hexadeca-1,3,5,7,9,12-hexaene. The proposed structure was elucidated, after its isolation using preparative liquid chromatography from the impurity enriched reaction crude sample, using analytical applications such as 1D NMR (1H, 13C and DEPT-135), 2D NMR (HMBC and COSY), high-resolution mass spectrometry (HRMS) and infrared spectroscopy (IR). The unknown impurity was prepared from brimonidine by following Ullman coupling reaction in the presence of CuBr 2 in gram scale with optimum purity to use further in analytical developments. The identification, structural elucidation and synthesis of unknown degradation impurity such as BMT-cyclized impurity, and HPLC method validation were reported for the first time in this paper. [ABSTRACT FROM AUTHOR]

• Use of fast Semi analytical method to model tire – pavement contact (compared to FEM) • Use of precise tire geometry (estimated by a photogrammetry method) and an equivalent Young's modulus (function of the inflation pressure resulting from a press load tests) • Effect of tire inclination in bend (or roundabout) on the calculated shear stresses (origins of damage in turns) • Importance of the contact parameters in the degradation of the pavement surface layers. Tire-pavement interaction is a rolling contact problem that depends on tire and pavement factors, such as vehicle speed and weight, material and type of tire, tire pressure inflation, camber and texture of the surface layer. In this paper, the problem of tire-pavement contact is studied using a realistic description in normal section and bend. The study focuses on the shape of the contact patch and the stress distribution at the tire-pavement interface and the surface shear stresses rather than internal stresses in the structure of the pavement. The numerical approach introduced requires precise tire geometry (estimated by a photogrammetry method) and an equivalent Young's modulus (function of the inflation pressure resulting from the press load tests). Vertical contact stress at the tire-pavement interface predicted by a Semi-Analytical model were compared to experimental measurements with a press system under different loads and angles of inclination. Finally, we discuss the effect of the tire inclination on the calculated shear stresses (origins of damage in turns). The model shows that the increase of the angle of inclination in a turn has a direct influence on the distribution of the tire-pavement contact stresses and the shear stresses. These results will provide indications for the evaluation of the performance of the surface layer with respect to rutting and downward cracking. [ABSTRACT FROM AUTHOR]

The research and developments in the field of defects and degradations (D & D) in crystalline silicon photovoltaic (PV) modules have been on the forefront, to ensure reliable long term operation of solar power plants worldwide. Thereby, to maintain the overall electrical integrity and performance of cells and modules, it is essential to improve the reliability of cell metallization (i.e., busbar and fingers) and interconnects against D & D in the outdoor field conditions. This paper presents a comprehensive review and analysis on the reported D & D in conventional screen printed metallization and soldered interconnects. The review has been presented on the basis of operating modes of degradation induced via thermo-mechanical fatigue, chemical mechanisms, manufacturing fallacies, and system voltage. Furthermore, for increased understanding of the underlying defect mechanisms, these D & D have been investigated for the respective modes of electrical loss, and sensitivity to common variable parameters like position, orientation and number of defects by electrical stimulation. The use of common characterization techniques for defect detection and analysis have also been presented, wherein, the effective use of imaging techniques is advised. Also, standard environmental tests, specified under IEC 61215 were found to induce finger and interconnect D & D like in field, however, defect specific tests may be devised for a detailed analysis. Finally, the precautions performed during the manufacturing processes, especially the soldering process are identified to be key in prevention of D & D in finger and interconnects. [ABSTRACT FROM AUTHOR]

Simple Summary: In the current study, we investigated changes in the levels of plant secondary metabolites (PSMs) in a rumen buffer in vitro model and identified the microbial dynamics of the rumen sample. The data suggested that the different types of PSM including luteolin, ferulic acid, caffeic acid, coumaric acid, rutin, myricetin, vitexin, kaempferol, and quercetin were decreased after 12 h of incubation in the rumen fluid (p ≤ 0.05). In contrast, the propyl gallate concentration was not significantly changed even after 24 h of incubation in rumen fluid compared to other metabolites. Microbial dynamics study showed that the Firmicutes, Bacterodetes, Actinobacteria, and Syngergistetes were the dominant phyla found in rumen fluids. Overall, data suggested that most polyphenolic compounds may degrade or reform new complex structures in the rumen. Further in vivo studies are needed to determine the PSM conversion rate and the final products from native PSM when undergoing degradation or reforming new complexes, and the effect on the microbiome. Plant secondary metabolite (PSM) degradations and feed breakdown into small particles may occur primarily in the rumen. It is possible to predict the rate and extent of feed disappearance in the rumen during incubation by different in vitro techniques, which differ based on the PSM structures, including phenolics, and flavonoids. However, PSM degradation and conversion efficiency in the rumen remains unclear. This study's objective was to evaluate the in vitro degradation of a group of PSMs in the rumen fluid, collected from Hanwoo steer samples. PSMs including rutin, vitexin, myricetin, p-coumaric acid, ferulic acid, caffeic acid, quercetin, luteolin, propyl gallate, and kaempferol were used in their pure forms at 1mg/250 mL in a rumen fluid buffer system. The mixture of selected PSMs and buffer was incubated at 39 °C for 12–72 h, and samples were collected every 12 h and analyzed by a high-performance liquid chromatography-diode array detector (HPLC-DAD) to determine the biotransformation of the polyphenolics. The results revealed that the luteolin, ferulic acid, caffeic acid, coumaric acid, rutin, myricetin, vitexin, kaempferol, and quercetin were decreased after 12 h of incubation in the rumen fluid (p ≤ 0.05) and were more than 70% decreased at 72 h. In contrast, the propyl gallate concentrations were not significantly changed after 24 h of incubation in rumen fluid compared to other metabolites. Finally, microbial dynamics study showed that the Firmicutes, Bacterodetes, Actinobacteria, and Syngergistetes were the dominant phyla found in rumen fluids. The data suggest that most polyphenolic compounds may degrade or reform new complex structures in the rumen. [ABSTRACT FROM AUTHOR]

A combined modelling-experiments approach is presented with the aim of determining in-situ key characteristics of a RFB. The porous electrode impedance was calculated and measured without and with a faradaic reaction, by means of a symmetric cell. The technique was applied to the specific [Fe(CN) 6 ]3-/[Fe(CN) 6 ]4- couple whose interest for RFB application is substantial. The interpretation of Electrochemical Impedance Spectroscopy (EIS) data enabled the determination of the key membrane and electrode resistances and the investigation of their evolutions during the battery operation. The effects of the cation composition in the supporting electrolyte, the carbon material and the cycling were analysed. The results gave insights on degradation mechanisms that can hinder RFB performance, and delineated the phenomena occurring during electrolyte circulation or during battery operation. [ABSTRACT FROM AUTHOR]