Development of Efficient Electrocatalysts for Lithium Oxygen Batteries

Rechargeable nonaqueous Li-O2 batteries are considered and are expected to be the most promising energy storage and conversion candidate for future electric vehicle applications due to their ultra-high theoretical energy density. Bright prospects can be easily imagined, but critical challenges remain. High overpotentials, low capacity, low rate capability, and short cycle life, which are mainly caused by the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) dynamics on the cathode, seriously hinder further development of this battery technology. The oxygen-breathing cathode, therefore, has been identified as a key factor influencing the overall performances of a nonaqueous Li-O2 battery. Searching for an efficient cathode catalyst combined with an optimum architecture should be the ideal pathway to address the current challenges. In this thesis, three-dimensional (3D) foam-like NiCo2O4, nanofibrous Co3O4/polypyrrole (PPy) composite, three-dimensional (3D) hierarchical porous Co3O4 nanotube (Co3O4 HPNT) networks, and Ag nanocrystals encapsulated in nitrogen-doped carbon fiber (NCF) have been synthesized and studied as cathode catalysts for Li-O2 batteries.