Browsing by Person "Konnerth, Philipp"

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Crucial interactions of functional pyrenes with graphite in electrodes for lithium‐ion batteries
(2023) Bauer, Marina; Konnerth, Philipp; Radinger, Hannes; Pfeifer, Kristina; Joshi, Yug; Bauer, Felix; Ehrenberg, Helmut; Scheiba, Frieder
Polycyclic aromatic hydrocarbons, such as pyrenes, are a well‐known material class for non‐covalent modification of carbon surfaces in many applications. In electrochemical energy storage, pyrenes are mostly used in large polymeric structures. This work addresses the use of carboxy‐ and amino‐functionalized pyrenes for graphite electrodes for lithium‐ion batteries (LIBs). Pyrenes are explored as adsorbed species on graphite prior to electrode fabrication and as additives to the electrode composition. Thereby, 1‐pyrenecarboxylic acid, 1‐pyrenebutyric acid, 1‐aminopyrene, and 1‐pyrenebutylamine were under investigation. As additives, pyrenes do not influence the cycling performance of the electrode at low current but deteriorate the performance at high current, regardless of the functional group. However, when the pyrenes are adsorbed to the graphite surface, the influence of the different functional groups becomes clearly visible, revealing that an additional butyl group has a positive impact on the cycling performance and lithium‐ion transport of the electrodes. Electrodes with 1‐pyrenebutyric acid even enhanced the performance compared to the pristine electrode.
Extraction of common microalgae by liquefied dimethyl ether: Influence of species and pretreatment on oil yields and composition
(2020) Bauer, Manuel C.; Konnerth, Philipp; Kruse, Andrea
Liquefied dimethyl ether (DME) is regarded as a promising, green solvent for biomass lipid extractions. It is non-toxic, applicable to wet feedstocks, and allows easy product separation by pressure reduction. Yet, knowledge about its usability in combination with oleaginous microalgae is limited. In the current work, four common microalgae and cyanobacteria species were used to study DME extraction characteristics: Arthrospira platensis, Nannochloropsis gaditana, Phaeodactylum tricornutum, and Scenedesmus almeriensis. Dried samples were subjected to a batch DME extraction and compared to a standard chloroform/methanol procedure. To evaluate the influence of pretreatment, particle size distributions of two different milling sequences (knife- and cryo-milling) and the resulting effects on DME extraction and oil composition were addressed. Additionally, an algae washing procedure was tested. DME extractions resulted in oil yields of 0.5–2.7% of dry mass (equal to 5–19% of total lipids) without further pretreatment. Cryo-milling reduced median particle sizes by 25–87% and simultaneously increased lipid yields to 1.7–5.6% of dry mass (17–50% of total lipids). Phaeodactylum tricornutum showed the highest extraction efficiency with DME, combined with a favorable fatty acid profile. Although being most affected by the additional milling pretreatment, Arthrospira platensis performed worst in both scenarios. DME extracted oils were generally characterized by enhanced contents of C14:0, C16:0, and C16:1 fatty acids. However, relative abundances were strongly influenced by the properties of the tested algae species. The additional cryo-milling pretreatment affected fatty acid compositions by increasing the shares of potentially valuable polyunsaturated fatty acids.