Investigation of novel, redox-active organic materials for lithium-ion and lithium-oxygen batteries
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
This thesis encompasses the successful synthesis, characterization (NMR, IR, TGA) and electrochemical testing of novel, potentially redox-active organic materials. These were destined as electrodes for Li-organic cells and/or as catalysts for Li–O2 cells.
The electrochemical performance of the dilithiated and tetralithiated salts of 2,5-dialkylamide hydroquinones (with ethyl, isopropyl or benzyl as the alkyl group) and of a partially lithiated polymer with a backbone of alternating 2,5-dicarbonylhydroquinone and 1,4-benzyl diaminophenylene units was evaluated. The small organicsalts exhibited redox-activity around 1.0 V vs Li/Li+ (the terephthaloyl redox system) and 2.8 V vs Li/Li+ (the quinone redox system). These values drifted depending on lithiation degree and alkyl substituent. Redox irreversibility featured these materials which decomposed and dissolved. The polymer exhibited multiple redox-activity in the region of 2.5-3.6 V vs Li/Li+, which was however also irreversible.
Further on, the small organic salts were tested as to their impact on the dischargeproduct (Li2O2) yield in Li-O2 cells. Discharge profiles of cells with and without the inclusion of the salts were contrasted to each other; the former having a jagged appearance, indicative of side-reactions. The O2 electrode was studied by XRD todetect the formed products and the amount of Li2O2 present was quantified throug htitration and UV-vis spectroscopy. Organic salt inclusion was found to negatively affect the Li2O2 formation and also attack the Li-electrode.
Place, publisher, year, edition, pages
UPTEC Q, ISSN 1401-5773 ; 16016
lithium-ion, lithium-oxygen, organic electrode materials, organic catalysts
IdentifiersURN: urn:nbn:se:uu:diva-304751OAI: oai:DiVA.org:uu-304751DiVA: diva2:1033790
Subject / course
Master Programme in Materials Engineering
Renault, Stéven, Doktor
Kassman Rudolphi, Åsa, DocentBrandell, Daniel