Despite recent advances in the state-of-the-art lithium ion batteries, their energy and power densities are insufficient for transportation applications. This project will examine a novel battery chemistry, namely, Lithium-air, which can exhibit a theoretical energy density of almost 2 orders of magnitude higher than lithium-ion batteries. However, before the promise of Li-air batteries can become a reality, a serious challenge that needs to be overcome and will be the focus of this work is the development of ?nanostructured air cathodes? that optimize transport of all reactants (oxygen, Li+ ions, and electrons) to the active catalyst surfaces and provide enough spaces for incorporation of solid lithium oxide products during battery discharge.
The specific objective of this proposal is to fabricate and study process-structure-performance correlation in a novel, hierarchically-ordered nanofiber-based architecture with the aim to develop efficient cathodes for Li-air batteries. A unique triaxial electrospinning technique will be used that will allow core-shell architecture to achieve well-controlled directed material assembly via a simple synthesis procedure. In addition to providing well-defined multi-phase reaction surfaces, the proposed electrode design will exhibit a hierarchical two-level pore structure; macropores from inter-fiber spacing inherent to electrospinning and mesopores, which will be created in the carbon core via controlled nanoscale material assembly. This structure will help optimize oxygen mass transport and surface area and provide sufficient pore space for incorporation of solid discharge products necessary to maximize discharge potential. Owing to the complexity of the proposed architecture, PI?s approach is to first independently understand the electrospinning behavior and process- structure correlation in each of the functional layers of the core-shell nanofiber and then leverage these learnings to study the complete architecture.
If successful, this work will develop batteries that possess significantly higher energy storage density than the current state-of-the-art Li-ion batteries. Such ability will allow them to successfully compete in the transportation sector and achieve a satisfactory driving range. In addition, the fundamental knowledge gained through this work on materials processing, structure and electrode design will also benefit supercapacitors and other battery chemistries. This project will involve 1 PhD graduate, several undergraduates and K-12 students/teachers, particularly females and those from under-represented minorities in interdisciplinary research activities via workshops, research-based course and hands-on research experiences.
