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Doctoral Examination: Materials Design for Liquid and Quasi-Solid-State Tellurium-Based Rechargeable Batteries
April 3 at 12:00 pm - 3:00 pm
Yue Zhang, supervised by Dr. Jian Liu, will defend their dissertation titled “Materials Design for Liquid and Quasi-Solid-State Tellurium-Based Rechargeable Batteries” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.
An abstract for Yue’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public.
Registration is not required for in-person defences.
Rechargeable lithium-ion batteries (LIBs) are regarded as promising battery technology in the applications of large-scale energy storage and electric vehicles due to the merits of high efficiency and long lifespan. Currently, LIBs are mainly challenged by the limited capacity of intercalation-type cathodes and safety issues caused by organic solvents. Recently, conversion-type elements sulfur (S) and selenium (Se) as alternative cathodes have encouraged tremendous studies owing to the remarkable capacity by two-electron electrochemical conversion. However, the further commercialization of Li-S or Li-Se batteries is impeded by the sluggish redox kinetics and indecent capacity caused by their intrinsic low electrical conductivity. Tellurium (Te) with considerably higher electrical conductivity and comparable volumetric capacity, has been focused on solving the problems of volume expansion and cycling instability since 2014. In this dissertation, durable liquid-based or quasi-solid-state Li-Te batteries are constructed via rational cathode structure design and electrolyte chemistry. The commercially available or as-synthesized activated carbons are employed as Te hosts to buffer the volume change of Te upon lithiation/delithiation. The role of pore structure (pore size, pore volume) on the electrochemical performance of Te/C cathodes is clarified to correlate the interplay between Te and C. The optimized porous carbons are found to ensure highly stable Te cathodes in Li-Te batteries. Moreover, flexible gel polymer electrolytes are prepared to solve the interface incompatibility in quasi-solid-state Li-Te batteries. Composite TexSy cathodes are further synthesized by the integration of low-cost S and high-conductivity Te to achieve excellent specific capacity and cycling stability. Theoretical calculations and comprehensive characterizations demonstrate the fast redox kinetics facilitated by Te and different working mechanisms in Li-TexSy batteries. Meanwhile, the study of electrolyte chemistry in K-Te batteries is involved in broadening the applicability of Te electrodes, including the fabrication of reinforced composite gel polymer electrolytes and the investigations of the K-Te reaction pathways and Te/electrolyte interface engineering design. The fundamental understanding of the Li/K-Te system is deepened by the systematic in situ or ex situ characterizations. It is expected that these studies will provide some viable strategies for the engineering design of Li/K-Te batteries, paving the way for developing high-energy-density battery technology.