Doctor of Philosophy (PhD)
The Lithium-ion battery (LIBs) system has dominated the battery market because of its superior energy and power density. Problems related to LIBs such as safety, scarcity of cobalt and lithium have led researchers to explore alternative battery systems. NH4+ ion is a nonmetal charge carrier with lower molar mass (18 mol g-1) and smaller hydrated ionic size (3.31 Å) which results in excellent electrochemical properties. Furthermore, NH4+ ion has a tetrahedral structure that has no preferred orientation as compared to spherical metal ions giving a different intercalation chemistry based on hydrogen bonding. These properties present physical characteristics for NH4+ ion to be an effective charge carrier.
This research outlines the development of high performance NH4+ ion batteries (AIBs), in terms of anode, cathode, and electrolytes to enhance their electrochemical performance. The first chapter presents polyaniline (PANI) which is facially synthesized by oxidative polymerization resulting in high surface area, improved conductivity, and high-capacity material for NH4+ ion storage. We further explored a quasi-solid-state electrolyte in the second chapter based on xanthan gum for application in a flexible AIBs based on NH4V3O8·ּ2.9H2O nanobelts cathode and PANI anode. The full cell showed high-capacity retention when bent at different angles illustrating high structural integrity maintaining good electrochemical properties. Chapter 3 an in-situ intercalation technique is used to synthesize polyaniline-intercalated vanadium oxide (PVO) with a nanoflower morphology for increased surface area and enhanced NH4+ ion (de)intercalation kinetics. The interlayer spacing was expanded between V-O layers offering large diffusion channels to accommodate NH4+ ions. The diffusion kinetics of the NH4+ ions, influenced by the hydrogen bonds formed between NH4+ ion and O2- in the host structure, were enhanced by the unique π-conjugated structure of PANI, leading to high capacity. The last chapter presents a metal free all organic AIB, that can operate at a low temperature of 0°C based on Polypyrrole (PPy) and PANI with 19m NH4CH3COO water in salt electrolyte (WiSE) . Additionally, the physiochemical properties of NH4+-based WiSEs are examined by Raman and nuclear magnetic resonance (NMR) spectroscopies, to explore their electrochemical behaviors and the fundamental effect of salt concentration on the electrolyte characteristics.
Kuchena, Shelton Farai, "Development of Novel Electrodes and Electrolytes for Safer Aqueous Ammonium Ion Batteries with Enhanced Performance." (2023). LSU Doctoral Dissertations. 6090.