Understanding interfacial phenomena for the creation of next-generation high-capacity battery electrodes

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GONZALEZ-DISSERTATION-2022.pdf (5.12 MB)
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Gonzalez, Miguel Angel
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School of Chemical and Biomolecular Engineering
School established in 1901 as the School of Chemical Engineering; in 2003, renamed School of Chemical and Biomolecular Engineering
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https://hdl.handle.net/1853/72991
Abstract
The electrochemical performance of a battery electrode is dictated by the synergistic interplay of the various components to control ionic transport, electronic conductivity, chemomechanical stability, among other characteristics. Using magnetite as a model anode active material, this thesis aims to understand how interfacial phenomena at key interfaces of the composite electrode affect the various electrochemical processes that dictate battery performance of high-capacity next-generation electrodes. Three main interfaces were explored namely: the particle-capping agent interface, the binder-capping agent interface and the binder-binder interface of a multi-component binder system. Chapter 2 investigates the effect the local surface chemical environment of the active material particle-capping agent interface has on lithium insertion kinetics and cycling retention of a composite electrode. Changes to the conductive chemical environment of the particle were conducted via attachment of PPBT, a mixed conductor, functionalized at various distances from the particle surface using different molecular spacers. Chapter 3 focuses on understanding the interactions between different oligomer capping agents and the polymeric binder interface. By attaching PEG, PEI, and PAA at different mass-loadings in the polymer-magnetite complex, the effect of differences in mixing compatibility from surface mixing energetics was observed in relation to electrode processing and electrochemical behavior. Chapter 4 investigates the effect of crosslinking interactions of a PAA/PVA co-binder system with varying chain lengths on electrochemical performance. Careful selection of chain lengths altered polymer network order and in turn affects cycling retention and specific capacity through changes of the mechanical properties within the polymeric binder. Through deliberate chemical modifications at distinct interfaces of a composite electrode, this work aims to elucidate experimental design frameworks applicable to a wide variety of active materials towards realization of robust, high capacity anodes for lithium-ion batteries.
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2022-08-24
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