Coming dissertations at Uppsala university
-
Pioneering Triethyl Phosphate-Based Liquid Electrolytes for Safe Lithium- and Sodium-Ion Batteries : From Fundamental Insights to Practical Applications
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-538054
State-of-the-art liquid electrolytes, composed of flammable organic solvents, pose serious safety risks in lithium- and sodium-ion batteries. Non-flammable liquid electrolytes, particularly those based on phosphate solvents, offer a promising solution. However, they still lack compatibility with the most widely accepted carbonaceous anodes, due to continuous electrolyte decomposition or solvent co-intercalation. This thesis investigates triethyl phosphate (TEP) as a non-flammable electrolyte solvent for both lithium- and sodium-ion batteries.
For lithium-ion batteries, an LHCE composed of 1.5 M LiFSI in TEP + diluent was examined. The effect of two diluents, bis(2,2,2-trifluoroethyl) ether (BTFE) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE), on solvation structure and electrochemical performance was investigated. It was shown by Raman and Nuclear Magnetic Resonance (NMR) spectroscopy that addition of both diluents in LHCEs resulted in minor changes in interactions between Li+, TEP and the diluents, while maintaining a similar solvation structure as in high concentration electrolytes. In a lithium-ion full-cell, based on LiNi0.6Mn0.2Co0.2O2 (NMC622) | graphite, LHCEs prevented continuous TEP decomposition and TEP co-intercalation.
For sodium-ion batteries, the effects of ethers as co-solvents in TEP, various sodium salts, and several additives were investigated. Co-solvation of TEP with diglyme and tetraglyme using sodium hexafluorophosphate (NaPF6) and sodium tetrafluoroborate (NaBF4) salts revealed a significant trend between ionic conductivity and viscosity. NaPF6-based electrolytes showed higher ionic conductivities than NaBF4-based electrolytes, despite higher viscosity. NMR and computational studies revealed stronger interaction of the BF4 anion with the first solvation shell indicating more ion-ion interactions, leading to lower ionic conductivity. Despite promising fundamental insights in physicochemical properties, glymes were unable to prevent TEP decomposition. The analysis of five sodium salts in TEP-based electrolytes - NaBF4, NaClO4, NaDFOB, NaFSI, and NaPF6 - identified NaDFOB and NaFSI as particularly effective, especially when combined with 1 wt.% VC. Notably, NaFSI in TEP with 1 wt.% VC demonstrated a capacity retention of 77% after 600 cycles in high mass loading Prussian white (PW) | Hard carbon (HC) full-cells. XPS measurements revealed that, with this electrolyte, an effective passivation layer could be formed, which was poor in TEP decomposition products. The use of various additives was investigated in a fluorine-free NaBOB TEP electrolyte and it was found that they form effective passivation layers in high-mass loading PW | HC full-cells, even outperforming conventional carbonate-based electrolytes.
This thesis presents several strategies to effectively minimize TEP decomposition, advancing the development of safe liquid electrolytes for lithium- and sodium-ion batteries.
-
Poetics of Value : The Form-Determination of Subjectivity in Contemporary American Poetry
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-536684
Poetics of Value studies the temporality of subject-production in capitalism. By staging a debate between Marxist value-form theory, black studies, and contemporary American poetry, this thesis pursues ways out of value’s form-determining production of subjectivity. Value-form theory posits the present as a generalizing moment of abstraction, in which concrete labour is distributed in undifferentiated units of socially necessary labour-time, which allows each commodity to find its universal equivalent in exchange. What this misses, however, is the past that survives differentially in productive bodies: capital requires labour to be both undifferentiated (as labour-power) at the site of exchange and differentiated (as racialization, gendering, etc.) at the site of production. This surviving, differential past is brought to fugitive presence in the critical modality of black studies. Where value-form theory understands the abstract temporality of value as primary, black studies posits the antagonistic survival of other temporalities as primary. By closely reading four contemporary American poets, this thesis proposes a poetics of value that merges the critical projects of value-form theory and black studies, locating the survival of sociality in a fugitive present beside the standardizing temporality of the capitalist value-form. Those four poets are Alli Warren, Rob Halpern, Rowan Ricardo Phillips, and Fred Moten.
-
Deciphering Adult Autism : Exploring Polygenic Risk, Brain Structure, Well-being, Migraine, and Mental Health Disorders
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-537917
This research work comprises four studies investigating mental health disorders, with a particular focus on Autism Spectrum Disorder (ASD, hereafter referred to as autism). The research integrates epidemiological perspectives and genetic frameworks to explore connections with well-being, conditions such as migraine, and neuroanatomical brain structure changes in adulthood, utilizing data from the large European population cohort, UK Biobank, with over half a million participants.
Paper I examined the relationship between job satisfaction, job tenure, and 16 self-reported physician posed diagnosed mental health conditions. The findings show that Neurotic & Stress Disorders, Eating Disorders, and Other Mental Health Disorders are strongly associated with lower job satisfaction and shorter job tenure, highlighting the impact of mental health on workplace participation. Personality trait neuroticism significantly influences job satisfaction but not job tenure.
Paper II explored the relationship between genetic predispositions for autism and five well-being traits (neuroticism, depression, loneliness, life satisfaction, and positive affect). Polygenic risk scores (PRS) for autism were significantly associated with decreased well-being, particularly an increased risk of negative traits such as neuroticism and depression, and reduced positive traits such as life satisfaction, highlighting the genetic basis of well-being in individuals with autism.
Paper III examined the genetic link between autism and migraine, revealing that individuals with a genetic predisposition for autism have an increased risk of migraine, including both major types, migraine with and without aura. While no moderating effect of sex was found, personality trait neuroticism significantly mediated the relationship between autism and migraine, emphasizing the complex genetic and pathophysiological connections between autism and migraine, with neuroticism playing a key role in mediating this association.
Paper IV investigated the association between autism polygenic risk scores and brain volume alterations in the cerebellum, brainstem, and global brain structures in adults. The results demonstrated significant correlations, with higher autism PRS linked to reduced brain volumes, particularly in the cerebellum and brainstem, highlighting the genetic influence on neuroanatomical changes in autism adulthood.
These studies highlight the intricate connections between mental health, genetics, and brain structure, offering valuable insights for improving workplace participation and well-being in individuals with mental health issues including autism.