Pekka Peljo

In this work, a series of chromium mixtures with N,O‐containing ligands were evaluated as candidate negolytes for iron–chromium flow batteries. Six systems were investigated, including three prepared with a single ligand and three prepared with pairs of chemically distinct ligands. The structurally characterized mixture‐1 was used as the reference, whereas the exact chromium coordination structures of mixtures 2–6 were not established. UV–vis spectroscopy was used to estimate the dissolved chromium concentrations of the studied mixtures in 1 M KCl. The results show that combining chemically distinct ligands increases dissolved chromium concentration, reaching up to approximately 150 mM compared with 13.5 mM for mixture 1. Cyclic voltammetry revealed that five electrochemically evaluated mixtures displayed quasireversible redox behavior, whereas one mixture did not show any clear redox activity. However, flow‐cell cycling of these electroactive mixtures at a nominal concentration of 10 mM revealed limited capacity utilization and substantial capacity fading. These results show that increasing the dissolved chromium concentration alone does not ensure improved electrochemical accessibility or stable flow‐cell cycling. Further optimization and solution‐speciation studies are required to improve cycling stability and identify the chromium species responsible for the observed electrochemical behavior.

This paper discusses the use of slang in the battery field and the associated misnomers.

Solar energy-driven hydrogen evolution reaction (HER) remains an important topic in energy-related research. A biphasic (aqueous–organic) system allows for a relatively simple design with a soft interface as a reaction site. The electron donor from the organic phase acts as both photosensitizer and catalyst, enabling HER from the hydrated protons in the aqueous phase in the presence of light. Here, we demonstrate a biphasic system allowing for continuous hydrogen photogeneration, with the organic phase reduced to a subnanoliter droplet of decamethylruthenocene (DMRc) solution in α,α,α-trifluorotoluene (TFT) placed on a recessed Pt microelectrode. Proton transfer to the TFT phase was ensured by negative chemical polarization of the liquid|liquid interface formed at the orifice of the microelectrode cavity. The whole system was kept in an Ar atmosphere, and the Pt microelectrode potential enabled electrochemical recycling of electron-donor molecules. H2 was detected at the scanning electrochemical microscopy (SECM) tip placed above the droplet only in the presence of light. Photogenerated HER was also observed in H2 atmosphere with protons locally generated at the SECM tip next to the liquid|liquid interface, indicating proton transfer. These results demonstrate that continuous photogenerated HER may be realized with the sustainable system consisting of a minimal volume of organic phase.

Prussian White-based boosters were prepared using four commercially available carbon materials as conductive additives and cycled at the storage tanks of flow batteries with ferri/ferrocyanide-based electrolytes. All systems underwent a 21–22 day charge–discharge cell test to assess their long-term cycling stability; boosters containing the carbon material YP-50F completed nearly twice as many cycles as the other studied carbons (e.g., 500 vs 194, for YP-50F and C65, respectively), exhibiting their faster charge–discharge behavior. Changing the carbon material had a slight effect on the capacity utilization of the solid boosters (variations ∼10% under similar conditions), and this trend persisted across all remaining experiments. A significant improvement in capacity was observed when increasing the ferri/ferrocyanide concentration from 0.1 mol L–1 to 0.8 mol L–1 in the electrolyte solution, with the maximum capacity utilization increasing from 22.1% to 94.8% for a booster made with YP-50F carbon material. The results suggest that the increased booster utilization capacity observed at higher electrolyte concentrations is related to an enhanced mass transfer through the particles and a better matching between the redox potential of the boosters and the electrolyte.

Systematic evaluation of redox-active molecules is central to the discovery of next-generation energy-storage chemistries, yet conventional electrochemical workflows remain limited by low throughput and poor cross-condition standardization. Here we present HT-EChem, a high- throughput electrochemical platform that integrates cyclic voltammetry (CV) with a 96 well plate format to enable rapid, reproducible measurements across large sample sets and controlled condition sweeps. HT-EChem operates at microliter-scale sample volumes, substantially reducing reagent consumption and enabling screening when material availability is limited. Using iron-aminopolycarboxylate complexes and representative organic redox molecules as model systems, the platform resolves pH-dependent shifts in redox potentials and changes in reversibility, enabling rapid construction of potential-pH maps and stability-pH profiles. High-density measurements distinguish ligand-dependent electrochemical behavior: Fe-PDTA exhibits dual reduction features consistent with an electrochemical-chemical (EC) sequence involving structural reorganization, whereas Fe-EDTA and Fe-DTPA show a single dominant reduction peak under comparable conditions. By combining automated sample handling with structured data processing, HT-EChem provides a scalable route to generate comparable electrochemical datasets for redox-material screening, mechanism-informed interpretation, and downstream computational analysis.

Urea reduced the aggregation of redox active molecules, but did not lead to improved capacity utilization.

The performance of the negatively charged aspartic acid‐functionalized naphthalene diimide (ASP‐NDI) in a flow battery is investigated in this article. The high concentration ASP‐NDI/ferrocyanide flow battery presented cycled for 79.8 days with an average coulombic efficiency of 99.9% and an energy efficiency of 87.5% at 20 mA cm ⁻² while accessing an over 90% of the theoretical capacity of ASP‐NDI with a capacity fade rate of 0.0275% per day that is the lowest reported for the NDI‐based flow batteries to date.