Highlights ORR-kinetics study on Pt and Ag by using thin-layer catalysts in a AEMFC at 80 °C. Ag shows a later onset potential for ORR and lower performance at high voltages. The Tafel slope of Pt is 75 mV dec−1 above 0.8 V, for Ag the slope is 160 mV dec−1. For Ag, a voltammetric anodic peak at 0.8 V, indicates formation of Ag2O. Ag performs better than Pt below 0.5 V, but its stability is affected above 0.8 V.

Inhomogeneous temperature distribution in a large-format lithium-ion cell or between cells in a module/pack may cause a non-uniform current distribution, causing a local difference in aging, and potentially faster global aging (capacity fade and impedance rise) of the module. To study this effect, LiNi1/3Mn1/3Co1/3O2/graphite lithium-ion pouch cells were cycled at 32, 36, and 40 °C as single cells and in parallel connection, representing uniform and non-uniform temperature distributions. The results show that the current distribution becomes less uniform after cycling at a higher rate and in a narrower state-of-charge range. Cycling with non-uniform temperature at 3C rate results in aging similar to that at the maximum uniform temperature, while at 1C rate the non-uniform aging follows the trend at the average temperature. The performance decay of the cells cycled at 3C is mainly driven by the cell at 40 °C which shows 30 % more capacity loss than the corresponding cell cycled singularly. This leads to additional considerations when designing for cycle life and reliability in fast charging applications and high-power applications such as in electric vehicles or frequency regulation in stationary storage.

Water is a key factor in anion-exchange membrane fuel cells, since it is both a product and a reactant, and humidifies the membrane and the ionomer phase. To optimize the operation conditions preventing cathode drying and anode flooding, better knowledge on the water transport is needed. In this work, the water transport across an AemionTM membrane is quantified for different applied water partial pressure differences and current densities. Two membrane thicknesses, 25 and 50 μm, are studied, as well as two gas diffusion layers (GDLs) of different hydrophobicity: the hydrophobic Sigracet 25BC treated with polytetrafluoroethylene (PTFE), and Freudenberg H23C2 being hydrophilic as it is not treated with PTFE. The measurements show that having a hydrophilic GDL on both electrodes results in poor electrochemical performance, and restricted water transport. Although the highest water molar flux was observed for hydrophilic GDL on cathode and hydrophobic GDL on anode, the best electrochemical performance was observed for the opposite combination. A water transport model considering absorption/desorption resistance, electroosmotic drag and diffusion was deployed. The best fit of the model to the experimental data was obtained with a water drag coefficient of 2, and almost about 30% difference in absorption/desorption coefficient due to different GDLs.

The hybrid hydrogen-manganese redox flow battery (H2-Mn RFB) is a promising and sustainable electrochemical system for long-duration energy storage. One strong reason is the excellent features of manganese, such as low cost, abundance, environmental friendliness, and relatively high standard potential (+1.51 V). Nevertheless, the electrochemical and kinetic parameters of manganese electrolytes have not been studied in detail for flow batteries. In the present work, the kinetics of the Mn2+/Mn3+ redox species in an electrolyte composed of 1M TiOSO4 and 1M MnSO4 in 3M H2SO4 were studied on carbon paper electrodes. The kinetic analysis of manganese redox species (Mn2+/Mn3+) in the presence of TiO2+ was performed using cyclic voltammetry and electrochemical impedance spectroscopy techniques within the H2-Mn RFB set-up. The results were compared to reference redox species vanadium (VO2+/VO2 +) within H2-V RFB system. The results showed that the heterogeneous electron transfer rate constant (8.6 x 10-7 cm s-1) of manganese is comparable to that of vanadium (4.8 x 10-6 cm s-1), with less than an order of magnitude difference between them. Cyclic voltammetry (CV) in flow battery setup was used to calculate kinetics data.MnSO4 and TiOSO4 with a 1:1 molar ratio in 3 M H2SO4 was optimal composition.Kinetic data of manganese was found pretty comparable to benchmark vanadium.The electrochemical impedance spectroscopy technique confirmed CV data.Hydrogen-Manganese flow battery showed 97% capacity retention for 40 cycles.

This study centers on investigating the influence of conductive additives, carbon black (Super P) and graphene, within the context of LiFePO4 (LFP)-impregnated carbon fibers (CFs) produced using the powder impregnation method. The performance of these additives was subject to an electrochemical evaluation. The findings reveal that there are no substantial disparities between the two additives at lower cycling rates, highlighting their adaptability in conventional energy storage scenarios. However, as cycling rates increase, graphene emerges as the better performer. At a rate of 1.5C in a half-cell versus lithium, electrodes containing graphene exhibited a discharge capacity of 83 mAhgLFP−1; those with Super P and without any additional conductive additive showed a capacity of 65 mAhgLFP−1 and 48 mAhgLFP−1, respectively. This distinction is attributed to the structural and conductivity advantages inherent to graphene, showing its potential to enhance the electrochemical performance of structural batteries. Furthermore, LFP-impregnated CFs were evaluated in full cells versus pristine CFs, yielding relatively similar results, though with a slightly improved outcome observed with the graphene additive. These results provide valuable insights into the role of conductive additives in structural batteries and their responsiveness to varying operational conditions, underlining the potential for versatile energy storage solutions.

The Tesla Model 3 is currently one of the most popular electric vehicle (EV) and was the best selling EV in 2020. In this article, performance and degradation of 21700 cylindrical cells, taken from a new vehicle, were studied by cycling within 10% State of charge (SOC) windows. Cells tested in either very high and very low SOC windows show faster degradation than at moderate SOC. In particular, the shortest service life was for cells cycled below 25% SOC. The ageing mechanisms of the cells cycled in these most extreme windows have been monitored by non-destructive electrochemical methods including analyses of differential voltage, incremental capacity, and voltage hysteresis. The combination of loss of lithium inventory (LLI) accelerated in early cycling by SiOx utilization, paired with loss of active material (LAM) of SiOx are responsible for the most rapid ageing, which is observed in the cells cycled in the 5%–15% SOC window. Calendar ageing, however, is not accelerated by storage at low SOC. The results from this study offer an understanding of the distinct, SOC-dependent ageing patterns observed in the cells. This understanding of the ageing mechanisms in different cycling and storage conditions can be used to recommend improved customer usage patterns and substantially extend the lifetime of lithium-ion batteries in operation.

Improved knowledge on Proton Exchange Membrane Fuel Cell (PEMFC) behaviour in the Intermediate Temperature (IT: 80-120 degrees C) is needed. Here, ionic conductivity and H2 permeability are analysed under H2/N2 using electrochemical impedance spectroscopy, linear sweep voltammetry for three catalyst-coated membranes (CCMs): Nafion HP (reinforced), Nafion 211 (non-reinforced) and a reinforced commercial membrane (RCM, membrane thickness 13 mu m). Multiple relative humidity (RH) levels and pressure configurations are analysed at IT. Results show that ionic conductivity and H2 permeability increase with temperature and RH. However, lower crossover is measured above 100 degrees C and wet conditions due to low H2 partial pressure. The highest crossover is measured with an overpressure on the H2 side which, especially for RCM, suggests possible convection. The membrane reinforcement might reduce the permeability and it decreases the conductivity. Mass spectrometry confirmed that sprayed CCMs suffer from higher crossover than pristine membranes, although the membrane thickness is unchanged.

This study presents the fabrication of LiFePO4 (LFP)-coated carbon fibers (CFs) as a positive electrode component for structural batteries, utilizing a spray coating technique. The successful coating of CFs through this method demonstrated their usefulness as efficient current collectors. The electrodes obtained using this method underwent electrochemical evaluations. Throughout the extended cycling tests at C/7, the maximum specific discharge capacity reached 146 mAh/g, maintaining a 77% capacity retention after 100 cycles. In rate performance assessments at the faster C-rate of 1.5C, the capacity measured 123 mAh/g, with a retention of 96%. The application of spray coating emerges as a promising technique for electrode production in structural batteries, showcasing its potential for optimizing performance in multifunctional energy storage systems.

Lignin is one of the most naturally occurring biopolymers on Earth and exists in a relatively large portion of the residual stream of the pulp and paper industry. Technical lignin is water-soluble, nontoxic, and rich in quinone-type groups; therefore, it could be a potential redox species for next-generation aqueous redox flow batteries (RFBs). Despite having attractive features, lignin does not show a reversible electrochemical behavior. Herein, we implemented a straightforward approach to modify the structure of soda-based lignin by oxidative depolymerization. The modified lignin showed good electrochemical activity through cyclic voltammetry with distinct redox peaks, which match lignin monomers, such as vanillin and acetovanillone. The modified lignin was used as the negolyte of the RFB setup with potassium ferrocyanide as the counterpart. The RFB was cycled for over 200 cycles with an average Coulombic efficiency of 91%. In addition, the modified lignin electrolyte maintained the (electro)chemical properties even after four months of storage, as proven by RFB tests.

Lithium-ion batteries have a great potential in stationary energy storage, both for first- and second life, but the understanding and tools to evaluate cell degradation needs to be improved. In this study, the degradation of batteries subjected to three types of stationary services, as well as the repurposing of cells from more demanding to a milder application is investigated. The milder cycle is frequency regulation with a maximum C-rate of 1.5 C (FR1.5C) and the more demanding cycles peak shaving with a C-rate of 1 C (PS1C) and FR and PS combined (FRPS2C). The main driver for accelerated capacity loss was identified as the state-of-charge (SOC) change during operation, increasing the rate of degradation for PS and FRPS. The cell impedance was measured and fitted to a physics-based model to deconvolute the sources of polarization increase. A tortuosity increase in the negative electrode was seen for all cells, as well as a resistance increase. FRPS2C and PS1C further showed a decrease in the electrolyte mass transport properties. When repurposed to the milder FR1.5C application, PS1C showed a clear decrease in capacity loss rate while more heterogeneous degradation might be the reason for a higher rate of degradation for the repurposed FRPS2C cell.