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. © 2022 The Author(s)

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 FeCl3.6H2O 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+/Li0 show the voltage profiles of Fe-BDC and a plateau capacity of around 175 mAh/g. © 2022 The Author(s)

The compound Ni3(C8H4O4)3(C3H7NO)3, poly-[tris(µ4-Benzene-1,4-dicarboxylato)-tetrakis(µ1-dimethylformamide-κ1O)-trinickel(II)], was synthesized by the solvothermal method prepared via reaction between NiCl2•6H2O 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 Ni3(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 ∼420 mAh g−1, which drops during consecutive scans but stabilizes at ∼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.

Detta förstudieprojekt har visat att vätgasdrift för timmerlastbilar ger något högre men ändå liknande kilometerkostnad som ren batteridrift, men snabbare tankning och längre körsträcka, vilket ger större flexibilitet för åkaren. Även biodrivmedel kan vara ett konkurrenskraftigt alternativ. Skogsindustrin är en av Sveriges största transportanvändare. För timmertransporter är lastbil det klart viktigaste transportslaget och skogsindustrins transporter motsvarar ca 17 % av Sveriges transporterade gods på väg. Ett alternativ för omställning av skogsindustrins transporter till fossilfrihet är förnybar vätgas, som kan produceras genom elektrolys med förnybar el. Precis som el ger vätgas inte upphov till några lokala emissioner vid användningen. Produktion av vätgas kan potentiellt ha synergier för skogsindustrins massabruk, som behov av syrgas och tillgång till överskottsel. Projektet har undersökt vätgas som alternativ för skogsindustrins transporter. Hela värdekedjan, inklusive produktion, komprimering, lagring, och användning inkluderas i analysen som beaktar kostnader, energieffektivitet och växthusgasutsläpp ur ett ”well-to wheel”-perspektiv. Studien inkluderar jämförelser med andra möjliga alternativ för att ställa om transporterna till fossilfrihet så som elektrifiering och biodrivmedel. Projektet har gett resultat som kommer att ligga till grund för en mer detaljerad projekteringsstudie inför ett framtida demonstrations- och pilotprojekt. Studien som finansierats av Trafikverket genom TripleF har genomförts av RISE tillsammans med 6 skogsindustribolag, tre företag från fordonsbranschen och två systemintegratörer med fokus på vätgas. Medverkande företag och organisationer: Sveaskog, SmurfitKappa, Metsä Group, Holmen, StoraEnso, BillerudKorsnäs, AB Volvo, Volvo Penta, Volvo CE, Nilsson Energy, Euromekanik, Energiforsk, Skogsindustrierna.

Detta förstudieprojekt har undersökt vätgas som alternativ för skogsindustrins transporter. Hela värdekedjan, inklusive produktion, komprimering, lagring, och användning inkluderas i analysen som beaktar kostnader, energieffektivitet och växthusgasutsläpp ur ett ”well-to wheel”-perspektiv. Projektet har genomförts av RISE tillsammans med följande företag och organisationer: Sveaskog, SmurfitKappa, Metsä Group, Holmen, StoraEnso, BillerudKorsnäs, AB Volvo, Volvo Penta, Volvo CE, Nilsson Energy, Euromekanik, Energiforsk, Skogsindustrierna.

Performance and aging of lithium-ion 18650 cylindrical cells containing NCA and Si-graphite composite electrodes are investigated during long-term low current rate (∼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 (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. © 2021 The Author(s). 

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. © 2020 The Author(s).

This work focuses on the synthesis of LiFePO4-PANI hybrid materials and studies their electrochem. properties (capacity, cyclability and rate capability) for use in lithium ion batteries. PANI synthesis and optimization was carried out by chem. 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 atm. The pristine and synthesized powders were characterized by XRD, SEM, IR and TGA. The electrochem. 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.

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.

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 is increasing. Waterelectrolysis to produce hydrogen with the use of electricity from renewable sources allows for storage of theenergy in the form of hydrogen. The gas can be utilized either back to the electric net or as fuel for FCEVs.However, the cost of water electrolysis systems needs to be reduced while the lifetime must be increased. Oneof the main limitations of the proton exchange membrane water electrolyser (PEMWE) system is the degradationof the membrane1. This limits the lifetime of the system and is expensive to replace. It has been shown thatimpurities from feed water and the degradation products from other component poison the membrane, loweringthe proton conductivity. Furthermore, metal ion impurities catalyse the formation of hydrogen peroxide at thecathode further contributing to irreversible membrane thinning2. In industrial systems, the water circulated tothe cells is purified to minimize the degradation. However, the purification limits the operating temperature ofthe systems and increases the total system cost2.The water quality used in most electrolysis cells today utilises ASTM type II deionized water. However, littleresearch is done on the limitations, and quantifying the reduction in efficiency dependent on the water quality.Dedigama et al.3 calculated the minimum flow needed, and further state that in industry, 5 times the necessaryflow of water is circulated to ensure proper wetting of the membrane. However, in research, an excess of wateris often used, up to 100 times higher flow than required, to exclude mass transport restrictions on thereactions3,4.Increasing temperature decreases the kinetic overpotential and increases the membrane conductivity4.However, also dissolution of the catalyst and degradation of the cell components increase with temperature.Furthermore, in industrial applications the maximum temperature of the water into the purification system is60°C5. Dependent on the aim of the research, experiments at temperatures as low as 25°C are performed to fitwith the industry, while others run at 80 or 90°C to probe the upper limits of current density and efficiency2.In this project we aim to analyse the effect of varying water purity on the membrane degradation in a single PEMelectrolysis cell test setup. Furthermore, the effect of changing temperature from 60 to 80°C on the impuritytolerance will be studied. The circulating feed water will be analysed with respect to conductivity, metal ion andfluorine concentration. A parallel “blank” system with only tubings, fittings etc will be assembled and comparedto the data measured from the electrolyser. Contaminating species will be added to the feed water to study theirimpact.