The Aluminum-Ion Battery: A Sustainable and Seminal Concept?

The expansion of renewable energy and the growing number of electric vehicles and mobile devices are demanding improved and low-cost electrochemical energy storage. In order to meet the future needs for energy storage, novel material systems with high energy densities, readily available raw materials, and safety are required. Currently, lithium and lead mainly dominate the battery market, but apart from cobalt and phosphorous, lithium may show substantial supply challenges prospectively, as well. Therefore, the search for new chemistries will become increasingly important in the future, to diversify battery technologies. But which materials seem promising? Using a selection algorithm for the evaluation of suitable materials, the concept of a rechargeable, high-valent all-solid-state aluminum-ion battery appears promising, in which metallic aluminum is used as the negative electrode. On the one hand, this offers the advantage of a volumetric capacity four times higher (theoretically) compared to lithium analog. On the other hand, aluminum is the most abundant metal in the earth's crust. There is a mature industry and recycling infrastructure, making aluminum very cost efficient. This would make the aluminum-ion battery an important contribution to the energy transition process, which has already started globally. So far, it has not been possible to exploit this technological potential, as suitable positive electrodes and electrolyte materials are still lacking. The discovery of inorganic materials with high aluminum-ion mobility—usable as solid electrolytes or intercalation electrodes—is an innovative and required leap forward in the field of rechargeable high-valent ion batteries. In this review article, the constraints for a sustainable and seminal battery chemistry are described, and we present an assessment of the chemical elements in terms of negative electrodes, comprehensively motivate utilizing aluminum, categorize the aluminum battery field, critically review the existing positive electrodes and solid electrolytes, present a promising path for the accelerated development of novel materials and address problems of scientific communication in this field

Detection of electrocatalytical and -chemical processes by means of in situ flow NMR spectroscopy

In situ studies of electrochemical processes using NMR offer valuable information on reaction mechanisms, kinetics, and species identification, making it a powerful tool in electrochemistry research. In this study, we present the design of an in situ redox-flow NMR cell that allows for a continuous flow of liquid (electrolyte) or gas, application of electrical voltage, and recording of NMR signals. The utility of this setup is demonstrated through two case studies: electrochemical copper deposition on a gold electrode and the electrochemical conversion of carbon dioxide into hydrocarbon products. Specifically, the presence of multicarbon products containing C–C bonds generated during the electrochemical reduction reaction is confirmed in the 2H NMR spectra in the latter example. These findings highlight the ability of the in situ redox-flow NMR cell to directly monitor reaction intermediates and products, thereby enabling the elucidation of reaction mechanisms for the efficient and selective production of valuable hydrocarbon products through the conversion of CO2 into value-added chemicals. In contrast to other reported in situ NMR cells, the presented cell is suitable for multiple uses, and allows detecting NMR signals not only from exhaust products but also from those formed on the catalyst surface

Electromechanical and electrochemical properties of highly filled Titanium composites for PEM bipolar plates

Titanium polymer composites are evaluated concerning their suitability as bipolar plates in acid water electrolysis as a replacement of milled Titanium bipolar plates. It turns out that our highly filled polymer composites with 80 wt.-% Titanium powder meet all criteria given by US Department of Energy concerning electric conductivity and mechanical stability. Concerning the electrochemical corrosion test, an improved behavior is obtained by coating the composites by a 0.5 μm thin Titanium layer. The coated Titanium composite bipolar plate has been successfully integrated in a PEM fuel cell. The polarization curves show good electrolysis performances for short time, but further improvements on the coating and the surface roughness need to be made for long-time stability

Vorrichtung und Verfahren zur Energiewandlung von thermischer Energie in elektrische Energie

Die Erfindung betrifft eine Vorrichtung (20, 21, 46, 47, 48) und ein Verfahren zur Umwandlung von thermischer Energie in elektrische Energie, wobei die Vorrichtung (20) zumindest eine Anordnung (19, 39, 41, 42) umfasst, die zumindest enthält - ein erstes elektrisch leitfähiges Kontaktelement (31), - ein zweites elektrisch leitfähiges Kontaktelement (32), - ein zwischen den beiden elektrischen Kontaktelementen (31, 32) befindliches Material (4), - einen ersten thermischen Energieträger (1) mit hoher Temperatur Th, - einen zweiten thermischen Energieträger (2) mit vorgegebener niedriger Temperatur Tt, wobei der erste thermische Energieträger (1) zumindest in Verbindung mit dem ersten elektrisch leitfähigen Kontaktelement (31) und der zweite thermische Energieträger (2) zumindest in Verbindung mit dem zweiten elektrisch leitfähigen Kontaktelement (32) stehen.; Dabei ist als Material (4) ein Material mit ionischem oder zumindest kovalentem Bindungscharakter eingesetzt ist, wobei das Material (4) innerhalb seines Volumens (22) mindestens eine Art von Defektspezies (12, 13) aufweist, wobei durch einen eingestellten Temperaturgradienten [Delta]T, ggf. um eine Temperatur (11) mit Tc eines existierenden Defektlöslichkeits-Phasensprungs (3), zwischen einer hohen Temperatur Th im ersten thermischen Energieträger (1) und einer vorgegebenen niedrigen Temperatur Tt im zweiten thermischen Energieträger (2) eine Umlagerung der Defektspezies im Volumen (6, 7) vorhanden ist, wobei ein erster Teil (6) des Volumens (22) des Materials (4) eine hohe Temperatur Th, ggf. oberhalb der Temperatur (11) Tc des Defektlöslichkeits-Phasensprungs (3), und ein zweiter Teil (7) des Volumens (22) des Materials (4) eine niedrige Temperatur Tt, ggf.; unterhalb der Temperatur (11) Tc des Defektlöslichkeits-Phasensprunges (3), aufweisen, so dass mittels des Temperaturgradienten [Delta]T eine Umlagerung der vorhandenen Defektspezies (12, 13) und ggf. ein Dipolmoment erreicht wird, wobei nach Beendigung der Umlagerung infolge des Aufhebens des eingestellten Temperaturgradienten [Delta]T eine Rückdiffusion der Defektspezies (12, 13), bedingt durch den aufgebauten Konzentrationsgradienten und ggf. ein aufgebautes elektrisches Feld, und somit eine elektromotorische Kraft zur Abnahme von gespeicherter elektrischer Energie aus dem Material (4) vorhanden ist