Life-cycle assessment and circular economy driven materials selection and numerical simulation of lithium-oxygen batteries

Abstract

Global decarbonization efforts are dependent on reliable energy storage, which itself depends on development of high energy density batteries. Commercialization of new battery chemistries is projected to expand the range of electric vehicles (EV) and enable electrified aviation. This is a nontrivial affair, as the physio-chemical processes for next-generation chemistries are not always well understood, and challenges with high capacity fade still persist. Even if development of new batteries is realized, there is no guarantee that a stable design is (a) compatible with the climate change mitigation or (b) possible due to supply chain limitations. This thesis presents an intersection between material science and battery modeling with the broader scope of life cycle assessment and materials sourcing. In Chapter 2 and Chapter 3, life cycle assessment is used to understand how material selection relates to environmental impacts for different Li-O2 battery designs. It is shown that attempts to decrease capacity fade and increase gravimetric capacity have resulted in material selection that is not always compatible with GHG emission reductions. From this, we conclude that the supply chain analysis, the circular economy, and life cycle assessment should be integrated more meaningfully into battery development, rather considered as an afterthought. To accomplish this goal, this work also presents the LCA for solvents, salts, catalysts, and current collectors that are commonly used in the Li-O2 battery space. In Chapter 4, attention is drawn to the lack of verified diffusion coefficients and solubilities in literature that can be used for battery modeling. Here, an open source, 1-D, continuum level battery model is used to explore the impact of validation parameters, such as diffusion coefficients, impacts cathode design. O2 diffusion coefficients and O2 solubility in Li-O2 electrolytes are shown to be crucial to accurately proposing cathode structures. The sensitivity of cathode mechanics to these properties allows us to identify gaps in experimental material property research, and make recommendations for future studies. Finally, the future environmental impacts and the lithium supply chain issues that may impact Li-O2 batteries are discussed in Chapter 5 and 6. The popularity of lithium metal anodes indicates that, while demand for materials such as cobalt or manganese may decrease, lithium will continue to be a crucial resource for energy storage. These chapters emphasises the importance of developing batteries with the circular economy in mind.