Advanced nanomaterial synthesis for energy storage applications

Abstract

The global energy crisis and climate issues have heightened interest in renewable energy and the use of renewable energy such as solar and wind power. However, in the case of solar and wind power, it is essential to develop an energy storage system that can store the electricity remaining due to the imbalance of energy supply and demand with other energy. The first way that electrical energy can be stored with other energy is by electrolyzing water to convert it into hydrogen as a environmentally friendly chemical energy. Second, there is a way to store electrical energy in batteries, which are electrochemical energy. For this purpose, the development of high-performance HER (Hydrogen) and OER/ORR (Zn-air battery) catalysts is essential, and based on this, the next-generation zinc-air battery was developed. Chapter 1 described the overall energy problem and the associated need for energy storage systems and working principals and improvement strategies for water splitting/zinc-air batteries. Chapter 2, we present the first demonstration of scalable synthesis of a low-cost highly-efficient CoSnSx/rGO hybrid catalyst via a facile hydrothermal approach. With highly exposed edges and excellent electrical coupling to the underlying reduced graphene oxide, the CoSnSx/rGO hybrid catalyst exhibited high HER activity with a low overpotential of 0.284 V, Tafel slope of ~80 mV dec-1 , large cathodic currents and high long-term durability in acid media. Chapter 3 demonstrates preferential in situ building of interfacial structures featuring the edge sites constituted by FeCo single/dual atoms with the integration of Co sites in the nitrogenized graphitic carbon frameworks (FeCo SAs@Co/N-GC) by electronic structure modulation approach. Compared to commercial Pt/C and RuO2, FeCo SAs@Co/N-GC reveals exceptional electrochemical performance, reversible redox kinetics, and durability toward oxygen reduction and evolution reactions under universal pH environments, i.e., alkaline, neutral, and acidic, due to synergistic effect at interfaces and preferred charge/mass transfer. Chapter 4 discusses the design of aqueous alkaline, non-alkaline and solid state electrolyte for ZACs based on developed pH-universal oxygen bifunctional electrocatalyst. The aqueous (alkaline, nonalkaline, and acidic electrolytes) ZACs constructed with a FeCo SAs@Co/N-GC cathode tolerate stable operations, have significant reversibility, and have the highest energy densities, outperforming those of noble metal counterparts and state-of-the-art ZACs in the ambient atmosphere. Additionally, flexible solid-state ZACs demonstrate excellent mechanical and electrochemical performances with a highest power density of 186 mW cm−2, specific capacity of 817 mAh gZn−1, energy density of 1017 Wh kgZn−1, and cycle life >680 cycles with extremely harsh operating conditions, which illustrates the great potential of triphasic catalyst for green energy storage technologies.