Failure Mechanics of Functional Nanostructures in Advanced Technologies

Title of Document: FAILURE MECHANICS OF FUNCTIONAL NANOSTRUCTURES IN ADVANCED TECHNOLOGIES Zheng Jia, Doctor of Philosophy, 2014 Directed By: Associate Professor Teng Li, Department of Mechanical Engineering The past decade has seen a surge of interest in developing novel functional nanostructures to enable advanced technologies, such as flexible electronics and high performance lithium-ion batteries. Examples of such functional nanostructures include organic/inorganic multi-layer thin films in flexible electronics and nano-sized silicon/tin-based anodes in lithium/sodium ion batteries. Widespread implementation of these advanced technologies with novel functional nanostructures in the future will broadly impact human’s daily life. However, grand challenges for developing robust novel functional nanostructures still exist. During operating cycles, these functional nanostructures undergo large deformation and high stresses, which may cause fracture and pulverization of the nanostructures, thereby leading to degradation and mechanical failure of the flexible devices or battery cells. Therefore, enhancing mechanical durability of the novel functional nanostructures in a mechanically demanding environment remains a significant challenge to the nanostructure design. This dissertation aims to shed lights on capturing the characteristics of the failure mechanisms of some novel functional nanostructures by theoretical and computational mechanics approach, The novel functional nanostructures investigated in my thesis includes inorganic/organic multilayer nanostructures, polyimide-supported brittle ITO films, substrate-supported ductile metal films and nanobead/nanowall/nanowire/nanoparticle electrodes in high-performance batteries. More importantly, we also explore possible solutions to effectively enhance the mechanical durability of these functional nanostructures. Failure Mechanics of Functional Nanostructures in Advanced Technologies