Hoppecke (Germany)

This work shows why the environmental impact of batteries should always be investigated on an application-specific basis.

This dataset encompasses a comprehensive investigation of combined calendar and cycle aging in commercially available lithium-ion battery cells (Samsung INR21700-50E). A total of 279 cells were subjected to 71 distinct aging conditions across two stages. Stage 1 is based on a non-model-based design of experiments (DoE), including full-factorial and Latin hypercube experimental designs, to determine the degradation behavior. Stage 2 employed model-based parameter individual optimal experimental design (pi-OED) to refine specific dependencies, along with a second non-model-based approach for fair comparison of DoE methodologies. While the primary aim was to validate the benefits of optimal experimental design in lithium-ion battery aging studies, this dataset offers extensive utility for various applications. They include training of machine learning models for battery life prediction, calibrating of physics-based or (semi-)empirical models for battery performance and degradation, and numerous other investigations in battery research. Additionally, the dataset has the potential to uncover hidden dependencies and correlations in battery aging mechanisms that were not evident in previous studies, which often relied on pre-existing assumptions and limited experimental designs.

Considerable structural changes are needed in public power grids to promote the use of renewable energies and increase in their share in electricity production and introduce and implement climate protection measures. Decentralized energy conversion systems (e.g., photovoltaics, wind power) must be incorporated into the power grid. Another challenge in planning and management is the interaction of existing facilities with the decentralized production and storage units to be incorporated. Stationary energy storage systems will become more important over the coming years, because there will be a need to manage a great number of fluctuating and decentralized energy generating plants. Electrochemical storage systems, consisting of cells or batteries, will be essential in this respect.

Abstract It is well known that lithium ion batteries degrade due to cycling (cycle life), but also when in standby mode with little or no current throughput (calendar life). Experimental results exist which show the lifetime of a battery under either of these conditions, cycling or standby operation. Results for an application specific mix of cycling and standby operation are, however, not readily available in the scientific literature. The ageing mechanisms of these two modes of operation differ in their impact on capacity and internal resistance as the two most important performance characteristics of a battery. The question is how the ageing mechanisms interact and how certain ageing mechanisms occurring particularly in one mode of operation affect ageing mechanisms which occur predominantly in the other mode of operation. As the conditions of use are very different in terms of current amplitude, state-of-charge and temperature, it is clear that the interaction needs to be considered taking the application into account by using application specific load collectives. This paper will discuss how to approach this problem, shows first results and their relevance for vehicle batteries when used for vehicle to grid operation.

Gewerkschaften sind, speziell in Deutschland, ein Gegenstand intensiver offentlicher Debatten, aber auch der akademischen Forschung, die diese Debatten zu fundieren hilft. Die letzte systematische Bestandsaufnahme der akademischen Forschung hat im Fruhjahr 2001 stattgefunden. Angesichts der recht dramatischen Krisenerscheinungen in den deutschen Gewerkschaften ist es an der Zeit, die neueren Forschungsergebnisse aufzuarbeiten. Der vorliegende Beitrag widmet sich dieser Aufgabe vor dem Hintergrund einer systematischen Literaturrecherche. Aus den insgesamt 79 als relevant eingestuften Forschungsbeitragen werden drei Themenkreise herausdestilliert und ausfuhrlich diskutiert: (1) die Mitgliedschaft in den deutschen Gewerkschaften, (2) die Gewerkschaften im deutschen System der Arbeitsbeziehungen und (3) die Erneuerung der deutschen Gewerkschaften. Die konstatierten Krisenerscheinungen werden durch die Studien eindrucklich belegt und erklart; es zeigen sich aber auch Defizite bei einzelnen Forschungsfragen und der Erarbeitung von Handlungsempfehlungen fur die Gewerkschaften.

A method is described to calculate molar solution energies from solubility data of a binary low-volatility organic compound+compressed carbon dioxide system. It has been applied to equilibrium measurements of the two anthraquinone derivatives 1,4-bis-(methylamino)-9,10-anthraquinone and 1,4-bis-(1-methylethylamino)-9,10-anthraquinone in CO2 within a p,T-range of 6.79–18.80 MPa and 299–345 K, respectively. Since solubility data do not exceed 0.135 g dm−3, the fluid phase can be regarded as infinitely dilute. The data have been analyzed in a way that from the two “derivative” plots logarithm of the solubility vs. the reciprocal temperature at constant pressure as well as constant density, two expressions for the molar solution energy, ΔsolEp and ΔsolEρ, have been derived and interpreted. We summarize our findings in four main statements: ΔsolEρ remains almost constant within a significant density range, here approximately between 400 and 800 kg m−3; ΔsolEp is drastically pressure (and density) dependent; both expressions are connected with each other via the isobaric expansion coefficient αp of the solvent; and finally for these two systems the ΔsolEp and ΔsolEρ values, respectively, are quite similar, whereas the solubilities differ by about a factor of ten.