UC Santa Cruz

The growing awareness of the detrimental effects of fossil fuel consumption on the environment has led to an increased demand for sustainable and clean energy sources worldwide. This has driven the development and application of electrochemical energy storage devices (EESDs), including rechargeable batteries and supercapacitors, in order to better utilize intermittent renewable energy sources such as solar and wind power, and to provide continuous and reliable power supply. The cathodes of EESDs have been found to play a critical role in determining their performance, including specific capacity, output voltage, rate capability, energy/power density, and efficiencies, as well as their calendar life, thermal stability, cost, and environmental impact. Unfortunately, cathodes are still one of the major challenges in the advancements of EESDs. Developing advanced cathodes based on different electrochemical energy storage mechanisms, such as electric double-layer capacitance, pseudocapacitance, bulk ion insertion/desertion, and conversion reactions, has been an important task in order to fulfill the demands of EESDs for different application scenarios.The scope of this dissertation covers the research of my past five years in designing and optimizing different types of cathodes for high-performance EESDs. Chapter one presents the background of EESDs and explains the advances of different types of cathodes for EESDs. Chapter two introduces a 3D printed porous carbon cathode templated by microporous metal-organic framework, which serves as EDLC-type cathodes for aqueous zinc-ion hybrid capacitors with high areal capacitance and energy density. Chapter three focuses on the graded design of a 3D printed graphene aerogel substrate, which improves electrodeposition uniformity and electrochemical accessibility of ultrahigh-loading MnO2 cathode based on lithium-ion insertion/desertion for non-aqueous lithium-ion hybrid capacitors with high volumetric energy density. A double-layered cathode dealing with the efficiency of iodide/iodine conversion chemistry for high-performance aqueous zinc-iodine batteries is discussed in Chapter four. Finally, in Chapter five, an outlook targeting the challenges and opportunities of developing advanced cathodes beyond cathode material itself is provided.