Investigation of Parameters Governing the Charge Transfer Reaction in Organic Cathodes for Multivalent BatteriesLužanin, Olivera (Avtor) Bitenc, Jan (Mentor) Cerkovnik, Janez (Komentor) redox-active organicsmagnesium batteriescalcium batterieselectrochemical impedance spectroscopyelectron microscopymultivalent ion diffusionThe transition from fossil fuels to sustainable energy alternatives necessitates a significant advancement in our ability to store energy on a much larger scale. Safe and inexpensive batteries are crucial for this endeavor. The past decade has witnessed a sharp increase in interest in post-lithium-ion battery technology, including multivalent batteries. By combining energy-dense metal anodes, such as Mg and Ca, with environmentally friendly and structurally diverse organic cathodes, the full potential of multivalent technology might be achieved. Despite intensive research efforts, multivalent-metal-organic batteries still lag behind their monovalent counterparts in electrochemical performance, primarily in terms of cathode capacity utilization. This thesis focuses on delving into the main factors contributing to this gap and exploring strategies to address this challenge. The research outlined in this dissertation is divided into two parts and it combines chemical synthesis and advanced electrochemical characterization to gain deeper insights into parameters governing the charge transfer reaction in organic materials. In the first part, we aim to identify a reliable electrochemical setup conducive to detailed kinetic studies of redox-active organic compounds. We proceed with electrochemical impedance spectroscopy measurements in such a setup, coupled with a combination of microscopy techniques, including focused ion beam scanning electron microscopy (FIB-SEM) and transmission electron microscopy (TEM). This methodology allows us to visualize multivalent ion distribution and evaluate ionic resistances. In the third chapter, we examine the electronic conductivity of organic materials and the implications it has on observed electrochemical performances. The second part of the thesis focuses on chemical synthesis, including miniemulsion polymerization for obtaining nanosized polymers, synthesis of organic polymers with various electronically and ionically conducting fillers, polymers with varying degrees of porosity, and polymers with different lengths of aromatic core and linkers. These efforts aim to assess the influence of structural and morphological factors on electrochemical performance in conjunction with Mg and Ca-based charge carriers. Across four chapters, we validate the applicability of the symmetric cell approach in galvanostatic and impedance investigation of organic polymers, propose a transmission line model elucidating how carbon nanotubes enhance the organic polymer and contribute to improved capacity utilization, develop a methodology for measuring electronic conductivities of polymers reduced in realistic battery conditions, and finally, draw comparisons between different structural and morphological factors affecting capacity utilization in Mg and Ca electrolytes. 20242024-07-11 10:45:00Doktorsko delo/naloga159514sl