Priprava kompozitnih anod za magnezijeve akumulatorje

Firm, Marko (author), Dominko, Robert (mentor)

Za uspešno komercializacijo magnezijevega akumulatorja je potrebno razviti ustrezne anodne in katodne materiale ter elektrolite, ki so kompatibilni z kovinskim magnezijem in z uporabljenim katodnim materialom. Pri uporabi magnezijeve folije za anodo se srečujemo z relativno visoko upornostjo, ki je posledica pasivacije površine magnezija in relativno majhne specifične površine za elektrokemijske reakcije. V tem delu smo pripravili aktiven in fin magnezijev prah s postopkom mehanskega mletja, ki bi lahko bil zanimiv tudi za industrijsko proizvodnjo. Magnezijeve delce smo mleli skupaj z dodatkom organskih topil in magnezijevih soli. Uspešnost zmanjšanja delcev in stopnjo kontaminacije prahu smo preverjali z vrstično elektronsko mikroskopijo in emisijsko disperzijsko spektroskopijo. Elektrokemijsko aktivnost prahu smo določevali z galvanostatskimi meritvami v 0,4 M raztopini Mg(TFSI)2:MgCl2 v 1-metoksi-2-(2-metoksietoksi)etanu (DIG) in kasneje v 0,8 M raztopini Mg(TFSI)2-2MgCl2 v 1,2-dimetoksi etanu (DME). Rezultati so pokazali, da je najprimernejše topilo za mletje magnezija tetrahidrofuran (THF). Z dodatkom reduktivnih specij smo zmanjšali organsko kontaminacijo prahu. Tako dobljen prah smo nadalje uporabili za izdelavo kompozitnih elektrod iz magnezijevega prahu, saj in veziva. Te elektrode so izkazale nižjo upornost, kot magnezijeva folija. Pri elektrodah smo najprej preverili učinkovitost odtapljanja in nalaganja magnezija v anodah iz različnih pripravljenih prahov. Preverjali smo tudi njihovo elektrokemijsko stabilnost pri spreminjanju deleža veziva in saj. Najbolj stabilno delovanje kažejo elektrode, ki imajo sestavo kompozita iz Mg prahu, ki je bil mlet v THF, saj in veziva v razmerju 88:10:2. Različne prahove in kompozitne anode smo na koncu testirali še v laboratorijskih akumulatorjih, kjer smo uporabili magnezij kot anodo in redoks aktivni organski material kot katodo. Rezultati so pokazali, da bolj stabilno delovanje dosežemo z večjimi delci Mg prahu, ki imajo manjšo aktivno površino.

• Language: Slovenian
• Keywords: mletje magnezija, kompozitne anode, magnezij organski akumulatorji
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2019
• PID: 20.500.12556/RUL-110302
• COBISS.SI-ID: 1538431171
• Publication date in RUL: 13.09.2019

Secondary language

• Language: English
• Title: Preparation of composite anodes for secondary magnesium batteries

Abstract

Successful commercialization of a magnesium battery requires the development of suitable anode and cathode materials and electrolytes that are compatible with metal magnesium and with used cathode material. When using magnesium foil as an anode, we encounter a relatively high resistance resulting from the magnesium surface passivation and the relatively small specific surface area for electrochemical reactions. In this thesis, we have prepared an active magnesium powder using a mechanical milling process, which may also be of interest to industrial production. The magnesium particles were milled together with the addition of organic solvents and magnesium salts. The particle size reduction and the degree of contamination of magnesium were examined by scanning electron microscopy and emission dispersion spectroscopy. Electrochemical activity of magnesium powder was determined by galvanostatic measurements in 0.4 M solution of Mg(TFSI)2: MgCl2 in 1-methoxy-2-(2-methoxy ethoxy)ethane (DIG) and later in 0.8 M solution of Mg(TFSI)2 -2MgCl2 in 1,2-dimethoxyethane (DME). The results show that the most suitable milling solvent for magnesium is tetrahydrofuran (THF). With the addition of reductive spices, we can reduce contamination of milled powder with organic side products. Thus obtained powder was further used for preparation of composite electrodes of magnesium powder with addition of carbon black and binder. First, we checked the efficiency of stripping and deposition magnesium on composite anodes, which we prepared from different powders. These electrodes exhibited lower resistivity than magnesium foil. We also checked their electrochemical stability whit a changing amount of binder and carbon black. The best performing electrode composite had a composition of 88: 10: 2 between Mg powder, carbon black and binder. Different powders and composite anodes were eventually tested in laboratory batteries, where magnesium was used as the anode and redox-active organic material as the cathode. The results showed that more stable performance is achieved with larger magnesium particles because they are having a smaller active surface.

• Keywords: Milling of metal magnesium, composite anodes, secondary magnesium organic batteries