Ajayan, Pulickel M2022-09-232022-082022-08-10August 202Castro, Samuel. "Synthesis and electrochemical evaluation of active materials for energy storage applications." (2022) Diss., Rice University. <a href="https://hdl.handle.net/1911/113282">https://hdl.handle.net/1911/113282</a>.https://hdl.handle.net/1911/113282EMBARGO NOTE: This item is embargoed until 2028-08-01Since its successful commercialization in the early 1990s, Li-ion batteries (LIBs) have been one of the key factors in the technological growth of portable electronics, the aerospace industry, biomedical applications, and means of transportation. Research in the battery field has focused on synthesizing insertion cathode materials that rely on transition metals like Co, Mn, and Ni to improve figures of merit like the energy density and life cycle while reducing the cost per energy unit. Recently, there's been an increasing interest in employing LIBs for operation in harsh thermal environments such as outer space, military conditions, the oil and gas industry, and applications with a demand for high-power applications that causes a rise in the internal temperature to higher than 80 C. Unfortunately, the state-of-the-art materials currently used in commercial LIBs (LCO, NMC, NCA) suffer from structural instability upon heating that causes cathode degradation and decreases the electrode/cell performance. There is an area of opportunity in the development of materials that are structurally and electrochemically stable at high temperatures (>55 ºC). In the quest for cathode materials for high-temperature LIBs, phase-changing materials that modulate their electrical properties upon heating appear as a possible solution. Furthermore, there is a focus on replacing components like Cobalt that are scarce and toxic, and their extraction involves an unethical workforce. Herein, Sulfur based cathodes gain attention due to their high theoretical capacity and low cost. This thesis concentrates the work done on the synthesis, structural characterization, and electrochemical evaluation of materials with potential applications as insertion and conversion cathodes for LIBs and Li-metal batteries. A Vanadium dioxide cathode material, synthesized by a hydrothermal reduction reaction, shows promising specific capacities, high-capacity retention, and better rate capability upon a reversible phase transition. A Sulfur-selenium cathode composite was synthesized on carbon matrixes and used as a cathode material in a next-generation battery.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Lithium-ion batterycathodevanadium dioxidesulfur-seleniumThesis2022-09-23