NEXT GENERATION ANODES FOR LITHIUM ION AND LITHIUM METAL BATTERIES
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Engineering of specific battery components can yield incremental gains in performance, but sustained advancements are derived from an understanding of charge transfer, interphase formation, and ion storage in the system. In this dissertation, the next generation of lithium-ion and alkali metal anodes are integrated with promising flame retardant electrolyte systems for safe and energy-dense portable storage devices. The intent of this research is to bring safe lithium ion batteries to the market without compromising performance and, more specifically, volumetric energy density. The first part of this dissertation describes the invention and optimization of a silicon-based additive which employs a solution-based process to functionalize silicon nanoparticle precursors. The additive is thoroughly characterized by chemical and electrochemical methods and the electrolyte interphase is improved by the attachment of partially reduced graphene oxide and sacrificial additive species. The design principles developed for the silicon-based system deviate significantly from those used for other conventional intercalation and host electrodes. As a result, in the second part of this dissertation, three chemically separable electrolyte systems, selected for their flame retardant properties, are individually investigated and tailored for energy-dense pouch cells. The bulk transport and interfacial properties of each electrolyte system are adapted to meet the industry standards of portable electronic devices. Insights into the preferred species for stable solid electrolyte interphase formation are discussed with an emphasis on the impact of fluorinated solvents and sacrificial additives. In the last part of this dissertation, alkali metal hosts are also proposed for chemistries beyond lithium ion. Novel synthesis methods including rapid joule heating are explored to form the innovative host architectures which greatly mitigate the coulombic inefficiency of metal stripping and plating in half and full cell configurations. The design principles outlined in this dissertation reveal how to successfully engineer the charge transfer, interphase formation, and ion storage of high capacity electrodes with safe electrolyte for state-of-the-art portable energy storage devices.