magistrsko delo
Janja Šuster (Author), Robert Dominko (Mentor), Igor Plazl (Thesis defence commission member), Boštjan Genorio (Thesis defence commission member)

Abstract

Magnezijevi akumulatorji so odlični kandidati za naslednjo generacijo akumulatorjev. Največji izziv pri njihovem razvoju je pomanjkanje primernih elektrolitov, ki omogočajo reverzibilno odtapljanje in nalaganje magnezija. V magistrskem delu smo v eksperimentalnem delu primerjali delovanje elektrokemijskih celic z elektroliti različnih generacij v kombinaciji z Mg kovinsko anodo in delovno elektrodo iz nerjavečega jekla. Kot predstavnika elektrolitov 1. generacije smo izbrali elektrolit z Grignardovim reagentom, kombinacijo PhMgCl in AlCl3, za pripravo elektrolitov 2. generacije smo uporabili soli Mg(TFSI)2 in MgCl2 v različnih razmerjih (1:1, 1:0,5) raztopljeni v topilu DGM, za elektrolite 3. generacije pa soli Mg(Al(hfip)4)2 in Mg(B(hfip)4)2, ki smo jih prav tako raztopili v DGM. Primerjali smo njihove Coulombske učinkovitosti nalaganja in odtapljanja Mg, prenapetosti, morfologijo depozitov ter elementno sestavo. Ugotovili smo, da ima od vseh testiranih elektrolitov 0,4 M APC v THF najvišjo povprečno Coulombsko učinkovitost (> 99 %), 0,4 M Mg(B(hfip)4)2 v DGM pa najnižjo prenapetost (~ 0,08 V). Elektrolita 2. generacije sta se v uporabljenem topilu najslabše izkazala, saj sta imela najnižje Coulombske učinkovitosti (< 90 %) in najvišje prenapetosti (> 0,27 V). Najboljše razmerje med visoko Coulombsko učinkovitostjo (> 98 %) in nizko prenapetostjo (< 0,1 V) je pokazal 0,4 M Mg(Al(hfip)4)2 v DGM. S pomočjo vrstičnega elektronskega mikroskopa smo v vseh primerih opazili heksagonalne depozite, ki so se pri nadaljnjem nalaganju Mg spremenili v skupke različnih oblik in velikosti. Z EDS detektorjem smo v vseh primerih potrdili, da so depoziti na delovni elektrodi kovinski magnezij.

Keywords

magnezij;Mg akumulator;Mg elektroliti;Mg kovinska anoda;katoda;elektrokemijska depozicija;morfologija;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [J. Šuster]
UDC: 621.355(043.2)
COBISS: 96395267 Link will open in a new window
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Downloads: 32
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Other data

Secondary language: English
Secondary title: Effect of different Mg electrolytes on the electrochemical performance of Mg metal anode
Secondary abstract: Magnesium batteries are one of the best candidates for the next generation of batteries. The biggest challenge in their development is the lack of suitable electrolytes that allow reversible deposition and stripping of magnesium. In this thesis, we compared the behaviour of electrochemical cells using electrolytes of different generations in combination with Mg metal anode and stainless steel working electrode. Electrolyte with Grignard reagent, more precisely combination of PhMgCl and AlCl3, was chosen as the representative of the 1st generation of Mg electrolytes, Mg(TFSI)2 and MgCl2 in different ratios (1:1, 1:0,5) dissolved in DGM for the 2nd generation electrolytes and Mg(Al(hfip)4)2 and Mg(B(hfip)4)2 also dissolved in DGM for the preparation of 3rd generation of electrolytes. We compared their Coulombic efficiencies of stripping and deposition of Mg, overvoltage, morphology of deposits and elementary composition. Of all tested electrolytes, 0,4 M APC in THF was found to have the highest average Coulombic efficiency (> 99 %) and 0,4 M Mg(B(hfip)4)2 in DGM the lowest overvoltage (< 0,08 V). Second generation electrolytes showed the lowest average Coulombic efficiency (< 90 %) and highest overpotentials (> 0,27 V). 0,4 M Mg(Al(hfip)4)2 in DGM showed the best ratio between high Coulombic efficiency (> 98 %) and low overvoltage (< 0,1 V). Using a scanning electron microscope, we observed hexagonal deposits at 50.000x magnification, that changed into clusters of various shapes and sizes with further deposition. EDS characterization of electrodes confirmed that the deposits on the working electrode are in fact metallic magnesium.
Secondary keywords: Mg battery;Mg electrolytes;Mg metal anode;electrochemical depozition;morphology;
Type (COBISS): Master's thesis/paper
Study programme: 1000376
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemijsko inženirstvo
Pages: 55 str.
ID: 14444855