Collaborative Research: Probing and Tailoring the Cathode-Electrolyte Interfacial Chemistries for Sodium Ion Batteries

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There is a critical need for improved energy storage technologies for electric vehicles and large-scale integration of renewable electricity grid storage to improve domestic energy security. Currently, state-of-the-art energy storage technologies such as lithium ion batteries are insufficient in providing the performance requirements needed such as cost and energy density to enable broad use. Alternative battery chemistries could provide an avenue towards gains in energy density, durability, and cost for these applications. This fundamental research project addresses the use of sodium ion batteries as a potential low-cost and sustainable solution to large-scale electrochemical energy storage systems. However, the inferior cycle life of cathode electrode materials for this type of battery is a significant roadblock towards commercialization. This project addresses the issue with a collaborative experimental program that focuses on cathode electrode material synthesis methods and experimental characterization tools that can measure the processes occurring at the interface region of the cathode electrode and the battery electrolyte. Fundamental knowledge will result on these processes and will enable rational design strategies to increase the durability, energy density, and cycle life of this battery type. For broader impacts, the project's partners will establish an energy storage research program at Jackson State University. An outreach program at each project institution will be enriched with educational modules and hands on activities for elementary school-age students with a learning disability in dyslexia via summer camps and learning centers and with enhanced parent participation. This project seeks to elucidate the interfacial degradation mechanisms of sodium cathode materials and to establish experimental approaches for tailoring and strengthening the cathode?electrolyte interface for sodium-ion batteries. The project will make use of advanced synchrotron X-ray and electron characterization tools to probe the battery chemistry in the temporally and spatially resolved environments. The project will improve the electrochemical kinetics of active particles and surface stability of cathode materials and thus their performance in sodium ion batteries. There is a need for a holistic study to understand the formation and evolution of the interfacial degradation as well as to quantitatively pinpoint its relationship with the surface oxygen reactivity and bulk redox chemistry. The doping approach will simultaneously mitigate the interfacial degradation and accelerate the bulk electrochemical kinetics. The research will accomplish the following objectives: (1) probing the multiscale interfacial chemical and structural transformations and investigating the relationship between sodium cathode surface chemistry, interfacial degradation, and electrochemical kinetics, (2) conducting spectroscopic and imaging measurements to spatially quantify the influence of the interfacial degradation on the bulk redox behavior of sodium cathode particles as a function of the state-of-charge, cycling history, and charging protocol, and (3) establishing approaches to tailor the cathode surface chemistry for mitigating the interfacial degradation and improving the sodium ion battery performance (e.g. energy density, cycle life, rate capability).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.