doktorska disertacija
Povzetek
Magnezijevi (Mg) akumulatorji so obetavni nasledniki litijevih (Li) akumulatorjev zaradi
izboljšane varnosti, volumetrične kapacitete, cene in večje dostopnosti materiala. Klasični
anorganski katodni materiali, kjer se kovinski ioni vgrajujejo v kristalno rešetko, se pri
multivalentnih Mg ionih ne obnesejo dobro. Veliko boljša alternativa so organski katodni
materiali, ki zaradi svoje odprte in prilagodljive strukture veliko lažje shranjujejo Mg ione.
Glavna tema disertacije so poliimidni polimeri kot katodni materiali v Mg akumulatorjih. Na
začetku smo se osredotočili na različne sintezne poti in opazovali kakšen vpliv imajo na
elektrokemijsko delovanje materiala. Elektrokemijsko delovanje v bolj uveljavljenih in
raziskanih Li akumulatorjih nam je služilo kot prvi pokazatelj delovanja polimera. Naslednji
korak je bila sinteza novih polimerov in raziskovanje njihovega elektrokemijskega odziva v Li
in Mg akumulatorjih.
V zadnjem delu dizertacije smo se osredotočili na sam mehanizem elektrokemijske reakcije v
Mg akumulatorjih. Delovanje poliimidov v Mg akumulatorjih smo primerjali s kinonskimi
materiali in ugotavljali, ali se redoks mehanizem med različnimi skupinami polimerov razlikuje.
Mehanizem shranjevanja naboja v poliimidih smo raziskovali s pomočjo in-operando
infrardeče spektroskopije, ki smo jo dodatno potrdili še s pomočjo teorije gostotnih
funkcionalov (DFT).
Zaradi netopnosti poliimidov smo bili znatno omejeni z analiznimi tehnikami. Uporabili smo
infrardečo spektroskopijo, jedrsko magnetno resonanco v trdnem, elementno analizo in
vrstično elektronsko mikroskopijo. Pri karakterizaciji spojin smo se osredotočili tudi na
potencialne nečistoče med polimernimi verigami.
Ugotovili smo, da so poliimidi elektrokemijsko aktivni v Mg akumulatorjih, potrdili smo tudi
njihov elektrokemijski mehanizem. Zaradi še večje kompleksnosti Mg sistema v primerjavi z Li,
njihovega delovanja v vlogi katode nismo mogli temeljito opredeliti. Na celotno delovanje
akumulatorja vpliva preveč med seboj tesno prepletenih in soodvisnih dejavnikov, še posebej
elektrolit in njegovo občutljivo ravnovesje elektrokemijsko aktivnih kompleksov.
Ključne besede
magnezij;baterije;organski katodni materiali;poliimidi;polimeri;mehanizem elektrokemijske reakcije;doktorske disertacije;
Podatki
Jezik: |
Slovenski jezik |
Leto izida: |
2022 |
Tipologija: |
2.08 - Doktorska disertacija |
Organizacija: |
UL FKKT - Fakulteta za kemijo in kemijsko tehnologijo |
Založnik: |
[T. Bančič] |
UDK: |
621.355:547.46'054.5(043.3) |
COBISS: |
103066115
|
Št. ogledov: |
157 |
Št. prenosov: |
39 |
Ocena: |
0 (0 glasov) |
Metapodatki: |
|
Ostali podatki
Sekundarni jezik: |
Angleški jezik |
Sekundarni naslov: |
Polyimides as organic cathode materials for magnesium batteries |
Sekundarni povzetek: |
Mg batteries are promising post-Li battery technology due to their improved safety,
volumetric capacity, price and abundance. It has been shown that traditional inorganic
intercalation cathodes are not the best fit for multivalent Mg ions, while organic cathode
materials seem as favorable option on account of their flexible, open structure.
This thesis is about studying polyimides as cathode materials in Mg batteries. Not much data
is published about polyimides as cathodes in Mg system and our goal was to explore their
general Mg electrochemistry. Initially we focused on exploring various synthetic conditions
and observed how it affected the electrochemical performance in a battery. Electrochemistry
in Li system served us as an early indicator how a certain polymer behaves as a cathode.
Besides having a better cycling performance in terms of stability, Li-organic system is more
understood. The next step was synthesis and battery cycling of some novel polymers, which
were not yet published at that point.
In the last part of the thesis, our focus was building better understanding of electrochemical
mechanism of charge storage in Mg system. We briefly compared polyimide Mg
electrochemistry to quinones to see if they share similar mechanism. More detailed study of
charge storage mechanism was performed by in-operando infrared spectroscopy, which was
supported by density functional theory study.
Because of polyimides insolubility, we were notably limited by possible analytical techniques.
We used elemental analysis, infrared spectroscopy, solid-state nuclear magnetic resonance
and scanning electron microscopy. Some effort was devoted to determination of possible
impurities within polymer chains.
Polyimides were found to be electrochemically active in Mg system, with confirmed
electrochemical mechanism of carbonyl bond reduction. Mg electrochemistry is even more
complex than Li and we could not thoroughly estimate role of polyimides as a cathode since
there seem to be many factors, that are tightly intertwined and co-dependent, especially
electrolyte and its fine balance of electroactive species. |
Sekundarne ključne besede: |
Mg batteries;organic cathode materials;polyimides;polymers;electrochemical reaction mechanism;Akumulatorji;Univerzitetna in visokošolska dela; |
Vrsta dela (COBISS): |
Doktorsko delo/naloga |
Študijski program: |
1000381 |
Komentar na gradivo: |
Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo |
Strani: |
IX, 125 f. |
ID: |
14900692 |