Development of novel synthetic and analytic protocols for cationic magnesium complexes relevant to battery applications

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2023
Thesis identifier
  • T16568
Person Identifier (Local)
  • 201862344
Qualification Level
Qualification Name
Department, School or Faculty
  • The inclusion of magnesium bis(trifluoromethane)sulfonimide (Mg(TFSI)2) or LiTFSI to different Mg electrolyte solutions has been shown to improve the effectiveness of the electrolyte solution, this thesis outlines synthetic methods of producing Mg complexes that include the TFSI moiety, and how through donor control, multiple different species can be obtained. The ‘all phenyl complex’ (APC) is one of the leading electrolyte solutions for rechargeable magnesium batteries. It uses starting materials PhMgCl and AlCl3 in THF solvent to generate electrochemically active species that show good reversable deposition of magnesium ions on a magnesium anode. A new atom efficient synthetic method to obtain one of the complexes found in these APC solutions, specifically [Mg2Cl3·6THF]+[AlPh4]‾, has been developed, its electrochemistry studied, DFT calculations performed and the scope of the reaction expanded to form new, previously unknown, complexes that could enhance our understanding of how these systems work. Based on our knowledge of cationic magnesium complexes and through synthesis of β-diketiminate (NacNac) magnesium complexes (originally intended for use as an electrolyte in magnesium battery systems) the ligand exchange reaction between (NacNac)MgAr and group 13 triaryl complexes, which results in the formation of new magnesium cationic complexes, have been examined and analysed in detail as part of this thesis. Finally, this thesis discusses rises and pitfalls of new methodologies developed (using Raman and IR spectroscopy) to study the operando behaviour of the benchmark electrolyte, the APC (synthesised via our new synthetic route). Using operando ATR-IR techniques two different spectroelectrochemical cell configurations are investigated. In one, a Pt gauze is used as a working electrode, whereas in the other case, a thin layer of Pt is coated onto the surface of the ATR crystal. ATR-IR measurements indicate substantial differences between the two electrode configurations which are discussed and analysed.
Advisor / supervisor
  • Robertson, Stuart
  • Wain, Andy
Resource Type
  • This thesis is restricted to Strathclyde users only from 25th May 2023 until 25th May 2028.