Enabling Sulfur-Based Beyond-Lithium Metal Batteries via a Mechanistic Understanding of Advanced Hybrid Cathodes and Borate Electrolytes

Using fossil fuels to generate electricity and power transportation is the primary source of anthropogenic carbon dioxide emissions that lead to climate change. The utilization of batteries to store renewable energy, such as solar and wind, is critical to lessen dependence on nonrenewable resources. However, lithium-ion batteries used in handheld devices and electric vehicles currently use expensive and rare materials that are not produced domestically, limiting affordability and domestic supply chain security. Developing batteries with low-cost, sustainable, and domestically-sourced materials such as sodium, magnesium, or calcium could overcome these challenges, but new chemistries are needed to increase the performance of batteries based on these materials. This research aims to lead the development of next-generation battery chemistries based on these elements to support the domestic production of low-cost battery solutions that increase the competitiveness and independence of the U.S. in the renewable energy sector. Moreover, this effort promotes inclusivity and fosters the growth of future scientists and engineers in this field. Currently, beyond Li-ion batteries have limitations due to their low-capacity cathodes and poor electrolyte stability. This makes them less competitive in high-energy density applications. The aim of this project is to create affordable and high-performance beyond Li-ion batteries that can compete in the market by researching reversible electrolytes and high-capacity cathodes for these batteries. The strategy for accomplishing this ambitious goal is to leverage a combined computational and experimental approach to: 1) investigate a set of high-energy density hybrid cathodes where sulfur is chemically bound to a catalytic substrate material, 2) discover advanced electrolytes based on the tunable borate chemistry, and 3) map the various reaction mechanisms based on novel cathodes and electrolytes to their macroscopic performance, which will inform the rational discovery of superior Na, Mg, and Ca anode chemistries. This mechanistic map will be iteratively applied and refined by computationally predicting superior hybrid cathodes and borate electrolytes, characterizing their performance, and revising the mechanistic understanding. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.