The Disputation will be live streamed for everyone else.
The livestream will be activated 15 minutes before the Defense starts.
Trial lecture
December 6th, 09:15 AM, Auditorium 3, Chemistry building
Trial lecture title: "Photobatteries – the principles and materials"
Kreeringssammendrag/Conferral summary
Utvikling av nye batterikjemier som kan tilby bedre ytelse enn dagens batterier er viktig for å kunne bli et helelektrifisert samfunn. Dette doktorgradsarbeidet har undersøkt en klasse av materialer for mulig bruk i positive elektroder i Li- og Na-ion-batterier som potensielt kan by på høyere kapasitet. Med en kombinasjon av eksperimentelle og teoretiske metoder har først fundamentale egenskaper ved disse materialene blitt undersøkt, og videre gjennom såkalte operando-eksperimenter har de kjemiske og strukturelle endringene i materialene under sykling av batteriene blitt undersøkt.
Main research findings
As we transition to a fully electrified society, it is clear that batteries are essential pieces in the overall energy puzzle. While current battery chemistries have gone far in revolutionising electric mobility, improved batteries are still needed for more demanding applications. At the same time, highly concentrated supply chains and increasing geopolitical tensions pose potential risks to the pace of electrification. As such, new battery chemistries that could address these issues are desirable. One interesting avenue of research is the study of Li/Na-rich electrode materials that promise higher capacities than current chemistries due to an additional redox contribution from the anionic framework.
This work explores one such class of materials: the antifluorite-type oxides. The series Li5+xFe1-xCoxO4 is synthesised and subjected to structural and magnetic characterisation. A selection of these materials (x = 0.0, 0.5, 1.0) are further tested as positive electrode materials in Li-ion batteries in which the chemical and structural evolution of the materials is tracked through operando experiments during initial charging over two distinct potential plateaus, and subsequent discharge following termination after each of these plateaus.
The Na-based analogue Na5FeO4 is also investigated using density functional theory to assess the suitability as a positive electrode material in Na-ion batteries, in which a potential reaction pathway that would allow reversible cycling is identified.
Candidate contact information
E-post: rasmusvt@smn.uio.no
Adjudication committee
Professor Dorthe Ravnsbæk
Intitut for Kemi, Århus Universitet, Denmark
Professor Daniel Bandell
Department of Chemistry, Uppsala Universitet, Sweden
Professor Reidar Haugsrud
Department of Chemistry, University of Oslo, Norway
Supervisors
Professor Helmer Fjellvåg
Department of Physics, University of Oslo, Norway
Associate Professor Vajeeston Ponniah
Department of Chemistry, University of Oslo, Norway
Chair of defence
Professor Steven Wilson
Department of Chemistry, University of Oslo, Norway