Although anion exchange membrane water electrolysis (AEMWE) shows promise for hydrogen production, the technology is still in the developmental phase. It faces substantial challenges, particularly concerning the long-term stability and durability of its components. A critical concern is the degradation of both the anion exchange membrane and the catalysts, which directly impact system performance and efficiency. This study investigates the degradation mechanisms of catalysts and membranes, with a focus on metal leaching, phase instability, and membrane thinning in AEMWE by investigating plasma-sprayed Ni 5 Fe 1 Mo 0.5 anode catalysts. Electrochemical assessments were performed in both full-cell and three-electrode configurations, followed by extensive post-test characterization to gain deeper insights into material degradation mechanisms. A key objective of this research paper is to highlight the importance of integrating electrochemical characterization, open-circuit voltage (OCV) monitoring, and post-test investigations to understand degradation pathways. While electrochemical performance indicators, such as polarization curves and high-frequency resistance (HFR), provide valuable operational insights, they do not fully capture the physical and chemical transformations and degradation that occur during cell operation. To address this gap, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) was used for post-test analysis of both the catalytic layers and membranes extracted from full-cell tests, as well as catalyst layers from three-electrode tests. Post-test characterization revealed significant changes in the catalyst layer. Notably, metal leaching and catalyst particle detachment from the substrate PTL were observed, probably due to abrasion during oxygen evolution and possibly also metal leaching. Additionally, membrane thinning and localized catalyst detachment were also seen during extended operation times, correlating with OCV decline, reduced HFR, and low cell voltage at low current densities. Our hypothesis regarding the observed OCV drop was attributed to increased hydrogen crossover due to membrane thinning. In the three-electrode cell configuration, a more specific understanding of anode-specific degradation pathways can be obtained. Notable structural transformations and changes in surface composition of the anode catalyst were identified. Given the strong correlation between membrane thinning and OCV decline due to hydrogen crossover, some additional techniques, such as in-situ gas chromatography and the use of a hydrogen sensor on the anode side, are recommended for future studies. These findings highlight the complexity of evaluating AEMWE system degradation solely based on electrochemical performance metrics and underscore the need to integrate post-test characterization and hydrogen crossover measurement into the development process. This multifaceted analytical approach is crucial for advancing AEMWE technology, addressing key stability challenges, and guiding the future design of more robust catalysts and membranes.

This work presents synthesis and spectroscopic characterization of a new metal-organic framework (MOF). The compound Fe-BDC-DMF was synthetized by the solvothermal method and prepared via a reaction between FeCl(3)(.)6H(2)O and benzene-1,4-dicarboxylic acid (H2BDC) or terephthalic acid using N,N-dimethylformamide (DMF) as solvent. The powder was characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR) analysis. The electrochemical properties were investigated in a typical lithium-ion battery electrolyte by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charging and discharging. The synthetized Fe-BDC-DMF metal-organic framework (MOF) contains a mixture of three phases, identified by PXRD as: MOF-235, and MIL-53(Fe) monoclinic with C2/c and P21/c space groups. The structure of the Fe-BDC is built up from Fe3+ ions, terephalates (BDC) bridges and in-situ-generated DMF ligands. The electrochemical measurements conducted in the potential range of 0.5-3.5 V vs. Li+/Li-0 show the voltage profiles of Fe-BDC and a plateau capacity of around 175 mAh/g. (C) 2022 The Author(s). Published by Elsevier B.V.

Green hydrogen technology, aimed at revolutionizing clean hydrogen production, has recently garnered significant attention. However, the pursuit of cost-effective methods for obtaining clean hydrogen remains a substantial challenge for various industries. Anion exchange membrane water electrolysis (AEMWE) has emerged as a promising solution, leveraging low-cost materials and high efficiency, thus attracting extensive interest from both researchers and industries. Yet, the adoption of AEMWE faces two major hurdles: its relative immaturity as a technology and the limited exploration of its durability and stability. Within the Production, Use, and Storage of Hydrogen (PUSH) Research Center, a collaborative effort involving Chalmers Technical University, Lund University, Umeå University, and Research Institutes of Sweden (RISE), we are dedicated to addressing the scientific and technical barriers currently hindering the seamless integration of hydrogen into sustainable energy systems. Our comprehensive research strategy encompasses every facet of hydrogen, including production, storage, distribution, and utilization, all working synergistically in harmony. One of the ongoing projects in this research center, conducted in cooperation with RISE, around enhancing the durability of components and devices through advanced testing techniques applied to AEMWE. This study present the results of a 2000-hour lifetime test and Accelerated Stress Testing (AST) conducted on a commercial Membrane Electrode Assembly (MEA), showcasing the system's remarkable stability. It must be mentioned that in the next step, these results will be compared with lifetime test and AST from MEAs from other partners within PUSH Research Center.

The electrical contact resistance is a key parameter for optimising both the bipolar plate of the polymer electrolyte membrane fuel cell (PEMFC) and the electrical contact of the power terminal of the stack. The contact resistance is affected by the conductivity, roughness, and hardness of the two contacting surfaces. Here, new, application-specific contact resistance measurement methods are proposed for both the stack power terminal, and the bipolar plate. The proposed methods are compared to methods from references as well as standards, and it is concluded that the uncertainty of the measurements can be reduced by changing the measurement setup, and that the influence of probe resistance on measurement results can be eliminated. Furthermore, the effect of different accelerated durability tests on the contact resistance of the power terminal is examined both on test coupons and on a prototype screw connection with an electroless NiP and an electroplated NiSn coatings. As expected, the NiSn coupons gives lower contact resistance after ageing as compared to the NiP. However, the increase in contact resistance seen on coupons after ageing is not observed on the prototype screw connection.

The compound Ni-3(C8H4O4)(3)(C3H7NO)(3), poly-[tris(mu(4)-Benzene-1,4-dicarboxylato)-tetrakis(mu(1)-dimethylformamide-kappa O-1)-trinickel(II)], was synthesized by the solvothermal method prepared via reaction between NiCl2 center dot 6H(2)O and terephthalic acid using N,N-dimethylformamide (DMF) as solvent. The structure was characterized by powder X-ray diffraction and infrared spectroscopy analyses. The electrochemical properties as a potential active material in lithium-ion batteries were characterized by electrochemical impedance spectroscopy and galvanostatic charge-discharge curves in a battery half-cell. The characterization results show that the coordination network contains one independent structure in the asymmetric unit. It is constructed from Ni2+ ions, terephthalate bridges and in-situ-generated DMF ligands, forming two similar two-dimensional (2D) layer structures. These similar 2D layers are in an alternating arrangement and are linked with each other by dense H-H interactions (45%) to generate a three-dimensional (3D) supramolecular framework with ordered and disordered DMF molecules. The electrochemical measurements, conducted in the potential range of 0.5-3.5 V vs Li/Li+, show that Ni-3(C8H4O4)(3)(C3H7NO)(4) has good electrochemical properties and can work as anode in lithium-ion batteries. The material presents an initial specific capacity of similar to 420 mAh g(-1), which drops during consecutive scans but stabilizes at similar to 50 mAh g(-1). However, due to the wide potential range there are indications of a gradual collapse of the structure. The electrochemical impedance spectroscopy shows an increase of charge transfer resistance from 24 to 1190 Ohms after cycling likely due to this collapse. (C) 2022 The Authors. Published by Elsevier B.V.

Performance and aging of lithium-ion 18650 cylindrical cells containing NCA and Si-graphite composite electrodes are investigated during long-term low current rate (similar to 0.1C) cycling protocol resembling charge/discharge profile of off-grid photovoltaic battery system. The cells are cycled within 30% and 75% state-of-charge ranges ( increment SOC) with low, middle and high cut-off voltages. Electrochemical impedance spectroscopy data of full cylindrical cells exhibit severe aging for cells that have been cycled at higher cut-off voltage of 4.2 V. Symmetric cell impedance from each electrode shows that aging of NCA is dominant over aging of Si-graphite. Using a Newman-based impedance model, the NCA symmetrical cells' impedance spectra are parameterized to evaluate the aging modes. The resulting parameterization confirms increased particles' surface film resistance due to possible electrolyte oxidation and tortuosity increase at high cut-off voltages. Cycling the cells with middle and low cut-off voltages causes few significant changes when compared to calendar-aged samples. This opens up the possibility to significantly increase battery lifetime for small photovoltaic battery systems in rural areas of Bolivia.

This work focuses on the synthesis of LiFePO4–PANI hybrid materials and studies their electrochemical properties (capacity, cyclability and rate capability) for use in lithium ion batteries. PANI synthesis and optimization was carried out by chemical oxidation (self-assembly process), using ammonium persulfate (APS) and H3PO4, obtaining a material with a high degree of crystallinity. For the synthesis of the LiFePO4–PANI hybrid, a thermal treatment of LiFePO4 particles was carried out in a furnace with polyaniline (PANI) and lithium acetate (AcOLi)-coated particles, using Ar/H2 atmosphere. The pristine and synthetized powders were characterized by XRD, SEM, IR and TGA. The electrochemical characterizations were carried out by using CV, EIS and galvanostatic methods, obtaining a capacity of 95 mAhg−1 for PANI, 120 mAhg−1 for LiFePO4 and 145 mAhg−1 for LiFePO4–PANI, at a charge/discharge rate of 0.1 C. At a charge/discharge rate of 2 C, the capacities were 70 mAhg−1 for LiFePO4 and 100 mAhg−1 for LiFePO4–PANI, showing that the PANI also had a favorable effect on the rate capability.

A quasi-realistic aging test of NCA/graphite lithium-ion 18650 cylindrical cells is performed during a long-term low c-rate cycling and using a new protocol for testing and studying the aging. This to emulate a characteristic charge/discharge profile of off-grid PV-battery systems. The cells were partially cycled at four different cut-off voltages and two state of charge ranges (ΔSOC) for 1000 and 700 cycles over 24 months. Differential voltage analysis shows that a combination of loss of active material (LAM) and loss of lithium inventory (LLI) are the causes of capacity loss. Cells cycled with high cut-off voltages and wide ΔSOC (20% to 95%) were severely affected by material degradation and electrode shift. High cut-off voltage and narrow ΔSOC (65% to 95%) caused greater electrode degradation but negligible cell unbalance. Cell impedance is observed to increase in both cells. Cells cycled with middle to low cut-off voltages and narrow ΔSOC (35%–65% and 20% to 50%) had comparable degradation rates to calendar-aged cells. Cycling NCA/graphite cells with low c-rate and high cut-off voltages will degrade the electrode in the same way high c-rate would do. However, low c-rate at low and middle cut-off voltages greatly decrease cell degradation compared to similar conditions at middle to high c-rate, therefore increasing battery lifetime.

With the introduction of fuel cell electric vehicles (FCEV), hydrogen gas produced without fossil fuels Is requiredto reduce the CO2 emissions. At the same time, the production of renewable energy ...

The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-dicarboxylate and DMF = dimethylformamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal–organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides interactions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF molecule, which shows positional disorder. Parallel planes are connected mainly through weak C—H...O, H...H and H...C interactions between DMF molecules, as shown by Hirshfeld surface analysis.

The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di­carboxyl­ate and DMF = di­methyl­formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal–organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter­actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol­ecule, which shows positional disorder. Parallel planes are connected mainly through weak C—H⋯O, H⋯H and H⋯C inter­actions between DMF mol­ecules, as shown by Hirshfeld surface analysis.

Modelling of electrochemical impedance spectroscopy (EIS) to predict aging in lithium ion batteries is a useful tool when performing a diagnosis of the state of health (SOH) of the battery. Aging of lithium ion batteries happens in applications from electric vehicles to stationary systems and is associated to capacity fade and impedance increase [1]. By predicting the aging parameters through modeling of EIS from separated electrodes, it is possible to estimate the SOH of the full cell and therefore improve its performance. In this work NCA and graphite electrodes were harvested from cylindrical cells aged under an off-grid PV/Battery system conditions and analyzed by means of EIS to determine the causes of electrode deterioration. The NCA/graphite cylindrical cells were calendar aged and cycle-aged between SOC 20-50 %, 35-65 %, 60-90 % and 20-95 % until end of test (EOT) is reached (e.g. 1000 cycles). The impedance behavior of the calendar and cycle aged cells were measured. Each electrode is carefully harvested once reached the EOT and electrochemically characterized using symmetric cells by means of EIS. A physics-based impedance model is employed to fit the experimental EIS of symmetrical cells using a least square fitting tool in COMSOL® Multiphysics 5.4. It is based on the pseudo two-dimensional (P2D) model [2] incorporating intercalation kinetics, mass and charge transport based on concentrated solution porous electrode theory. The model additionally accounts for double layer effect and aging mechanisms. Using the model, useful aging parameters were parameterized, and the variation of the aging parameters with different aging history was validated with the support of scattered electron microscopy (SEM) technique. Among the aging mechanisms described, an increase in the local contact resistance between the active material and the conductive carbon, and decrease in particle size due to particle cracking and further film formation due to SEI are considered. The impedance model parameters from both electrodes are then linked to the aging process observed on experimental full cell. Figure 1 shows the fitting and experimental curves for graphite Nyquist plot, in which we observe a good fitting specifically at low frequencies. Although the model predicts a second semicircle in the middle requency range, the experimental curve also shows a time constant element which can be considered as a truncated semicircle in the same region. [1] T. G. Zavalis, M. Klett, M. H. Kjell, M. Behm, R. W. Lindström, G. Lindbergh, Electrochemica Acta, 110 (2013) 335-348. [2] J. Newman and W. Tiedemann, AIChE J., 21, 25–41 (1975). Figure 1

The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di-carboxyl-ate and DMF = di-methyl-formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal-organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter-actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol-ecule, which shows positional disorder. Parallel planes are connected mainly through weak C-H⋯O, H⋯H and H⋯C inter-actions between DMF mol-ecules, as shown by Hirshfeld surface analysis.

The crystal structure of the title compound, [Ni-3(C8H4O4)(3)(C3H7NO)(4)], is a two-dimensional coordination network formed by trinuclear linear Ni-3(tp)(3)(DMF)(4) units (tp = terephthalate = benzene-1,4-dicarboxylate and DMF = dimethyl-formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal-organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides interactions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF molecule, which shows positional disorder. Parallel planes are connected mainly through weak C-H center dot center dot center dot O, H center dot center dot center dot H and H center dot center dot center dot C interactions between DMF molecules, as shown by Hirshfeld surface analysis.

More flexibility measures are required due to the increasing capacities of variable renewable energies (VRE). In buildings, the integration of energy supplies forms integrated energy systems (IES). IESs can provide flexibility and increase the VRE penetration level. To upgrade a current building energy system into an IES, several energy conversion and storage components are needed. How to decide the component capacities and operate the IES were investigated separately in studies on system planning and system operation. However, a research gap exists that the system configuration from system planning is not validated by actual operation conditions in system operation. Meanwhile, studies on system operation assume that IES configurations are predetermined. This work combines system planning and system operation. The IES configuration is determined by mixed integer linear programming in system planning. Actual operation conditions and forecast errors are considered in system operation. The actual operation profiles are obtained through year-round simulations of different energy management systems. The results indicate that the system configuration from system planning can meet energy demands in system operation. Among different energy management systems, the combination of robust optimization and receding horizon optimization achieves the lowest yearly operation cost. Meanwhile, two scenarios that represent high and low forecast accuracies are studied. Under the high and low forecast accuracy scenarios, the yearly operation costs are about 4% and 6% higher than that obtained from system planning.

Rural electrification programs usually do not consider the impact that the increment of demand has on the reliability of off-grid photovoltaic (PV)/battery systems. Based on meteorological data and electricity consumption profiles from the highlands of Bolivian Altiplano, this paper presents a modelling and simulation framework for analysing the performance and reliability of such systems. Reliability, as loss of power supply probability (LPSP), and cost were calculated using simulated PV power output and battery state of charge profiles. The effect of increasing the suppressed demand (SD) by 20% and 50% was studied to determine how reliable and resilient the system designs are. Simulations were performed for three rural application scenarios: a household, a school, and a health centre. Results for the household and school scenarios indicate that, to overcome the SD effect, it is more cost-effective to increase the PV power rather than to increase the battery capacity. However, with an increased PV-size, the battery ageing rate would be higher since the cycles are performed at high state of charge (SOC). For the health centre application, on the other hand, an increase in battery capacity prevents the risk of electricity blackouts while increasing the energy reliability of the system. These results provide important insights for the application design of off-grid PV-battery systems in rural electrification projects, enabling a more efficient and reliable source of electricity.

The increasing penetration level of renewable energies requires more flexibility measures at the consumption side. Flexible energy prices have been placed by energy providers to promote flexibility measures from energy users. However, because of the current energy supply system in buildings, these flexible energy prices haven’t been fully taken advantage of. This study focuses on the integrated energy supply system in buildings. A Swedish office building is used as the case study. The integrated energy supply system is built by installing new components, including battery, heat pump and electrical heater, and hot water tank. Mixed Integer Linear Programming (MILP) problems are solved to determine the optimal component capacities and operation profiles. The results indicate that all the studied system configurations achieve lower net present cost (NPC) than the current system. It suggests that the integrated energy supply system can take advantage of the flexible energy prices and lower the overall energy cost in the building. Among the studied configurations, the combination of air source heat pump (ASHP) and electrical heater (EH) has the lowest investment cost. This combination also has the lowest NPC except in the scenario with low borehole cost.

The aging of lithium ion batteries in off-grid photovoltaic (PV) energy systems is evaluated. Off-grid PV systems can improve their reliability and efficiency by storing the excess of energy produced during sunny days and using it when no other source of energy is available. Due to its high energy density, high efficiency, and constantly drop in prices, lithium ion batteries are the most suitable option to be integrated in the system as energy storage [1]. Although the impressive features, lithium ion batteries properties need to be studied further in order to achieve more efficient renewable energy systems [2]. One of the determinant property to be evaluated is the lifetime of the lithium ion battery, which is determined by aging factors [3]. In this work we have studied the capacity fade and impedance increase as aging factors. State of charge (SOC) profiles corresponding to most common applications found in off-grid PV-systems were used to cycle NCA/graphite cylindrical for 8 months in the laboratory. Four SOC ranges were used to cycle the cells; Low ΔSOC (20% to 50%), middle ΔSOC (35% to 65%), high ΔSOC (65% to 95%), and and full ΔSOC (20% to 95%). Electrochemical techniques were used to characterize both capacity fade and impedance increase in full cells. Discharge at C/25 rate was performed to measure the capacity every 100 cycles. Impedance increase due to the solid electrolyte interface (SEI) formation and other unwanted process was determined by performing electrochemical impedance spectroscopy (EIS) measurements along with hybrid power pulse characterization techniques. Half cells and symmetrical cells were built to identify aging process on the NCA and graphite electrodes independently with the same electrochemical techniques described above. From Figure 1-a) we can observe a relatively large capacity fade of the C/25 discharge capacity on cells cycled at high ΔSOC, and almost similar behavior was observed in cells cycled at full ΔSOC. Whereas, for cells cycled at low ΔSOC and middle ΔSOC the capacity fade is small in comparison. Comparison between dV/dQ curves show a shifting and growing of peaks as the number of cycles increase. These changes are more evident in cells cycled at high ΔSOC and full ΔSOC, Figure 1-b). The EIS measurements show a relatively large increase of impedance in the Nyquist plot for the cells cycled at high ΔSOC and full ΔSOC, along with a formation of a second semicircle at the mid frequency range, which is also observed for cells cycled at low ΔSOC and middle ΔSOC, Figure 1-c). Bibliography [1] D. Parra and M. K. Patel, “Effect of tariffs on the performance and economic benefits of PV-coupled battery systems,” Appl. Energy, vol. 164, pp. 175–187, 2016. [2] Y. Zhang, A. Lundblad, P. E. Campana, F. Benavente, and J. Yan, “Battery sizing and rule-based operation of grid-connected photovoltaic-battery system: A case study in Sweden,” Energy Convers. Manag., vol. 133, pp. 249–263, 2017. [3] M. Klett, R. Eriksson, J. Groot, P. Svens, K. Ciosek Högström, R. W. Lindström, H. Berg, T. Gustafson, G. Lindbergh, and K. Edström, “Non-uniform aging of cycled commercial LiFePO4//graphite cylindrical cells revealed by post-mortem analysis,” J. Power Sources, vol. 257, pp. 126–137, 2014. Figure 1

The increasing penetration level of renewable energy requires more flexibility measures to be implemented in future energy systems. Integrating an energy consumer's local energy supplies connects multiple energy networks (i.e., the electrical grid, the district heating network, and gas network) in a decentralized way. Such integration enhances the flexibility of energy systems. In this work, a Swedish office building is investigated as a case study. Different components, including heat pump, electrical heater, battery and hot water storage tank are integrated into the electricity and heat supply system of the building. Special focus is placed on the flexibility that the studied building can provide to the electrical grid (i.e., the building modulates the electricity consumption in response to the grid operator's requirements). The flexibility is described by two metrics including the flexibility hours and the flexibility energy. Optimization of the component capacities and the operation profiles is carried out by using Mixed Integer Linear Programming (MILP). The results show that the system fully relies on electricity for the heat demand when not considering the flexibility requirements of the electrical grid. This suggests that district heating is economically unfavorable compared with using electricity for the heat demand in the studied case. However, when flexibility requirements are added, the system turns to the district heating network for part of the heat demand. The system provides great flexibility to the electrical grid through such integration. The flexibility hours can be over 5200 h in a year, and the flexibility energy reaches more than 15.7 MWh (36% of the yearly electricity consumption). The yearly operation cost of the system slightly increases from 62,273 to 65,178 SEK when the flexibility hours increase from 304 to 5209 h. The results revealed that flexibility can be provided from the district heating network to the electrical grid via the building.