Abstract
Booming populations and the emphasis on sustainability have put enormous pressure on energy storage and energy saving, which make us to rethink the exploitation of clean energy resources and the improvement of energy usage efficiency. Graphene is expected to hold the key to high-performance energy storage devices and novel, energy-saving materials. As a single layer of carbon atoms, the strong sp2 bonds and the free-standing π bonds render graphene unique and incredible mechanical, electronic, and thermal properties. However, after a decade of extensive study, how to effectively use graphene and its potential remains a challenge. The agglomeration, degradation, and side reactions may largely deteriorate the properties of graphene, leading to minor, even negative effects on final product performance. In this dissertation, graphene was employed in both Li-S batteries and metal matrix composites, aiming to develop effective and efficient approaches of using graphene in electrochemical energy storage and energy-saving materials. Specifically, in Chapter 2, graphene was incorporated with porous carbon derived from two common biowastes, banana peel and paper cardboard. The hierarchical pores in these two biomass-derived carbon frameworks and the outstanding conductivity of graphene enhanced the performance of Li-S batteries. In Chapter 3, it was unveiled that Li-S batteries failed due to the growth of mossy Li, which originated from imperfections on the solid-electrolyte interface (SEI). Accordingly, a stronger artificial SEI was built by combining alpha-lipoic acid (ALA), a low-cost dietary supplement, with graphene oxide, which effectively prevented the growth of Li whiskers. In Chapter 4 and Chapter 5, graphene was added to Al and Ni powders, separately, for the fabrication of metal matrix composites with a nacre-like microstructure. Interfacial reactions between graphene and both metals were strategically leveraged to mimic the microscale architectures of nacre. The fabricated Al/Al2O3/graphene composite and Ni/NiC3 composite displayed a joint improvement in a range of mechanical properties. The studies provide new inspirations for the development of high-performance, low-cost Li-S batteries and high-strength, high-toughness metal matrix composites, demonstrating that graphene can drastically change energy storage and energy saving if used smartly and effectively.
