CAREER: Enabling High-performance Na-ion Battery Cathodes Via Structural Pillaring

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The transition to renewable energy sources calls for large-scale energy storage solutions to cope with the intermittent energy generation by renewables, such as solar and wind. While lithium (Li)-ion batteries are widely used in portable devices and electric vehicles for energy storage, the high cost of lithium resources poses barriers to their adoption in large-scale applications, such as electric grid energy storage. Sodium (Na)-ion batteries are promising alternatives to Li-ion batteries for large-scale deployment because of the ubiquity of sodium. However, current Na-ion batteries are plagued by several deleterious processes, which compromise their performance and undermine their deployment for grid energy storage. Strategies to overcome these shortcomings must be developed to realize high-performance Na-ion batteries. The research project will investigate structural pillaring as an effective strategy to address the challenges of Na-ion battery electrodes. The research program will train both undergraduate and graduate students for the clean energy workforce in the United States. The educational and outreach programs will implement an interactive pedagogy in teaching and promoting the science of electrochemical energy storage to an audience at all levels. This will involve the development of educational games as a platform to engage learners at all levels. These educational kits will be integrated into the curriculum development on electrochemical energy storage and various outreach programs targeting both K-12 students and teachers.The goal of the research is to elucidate the fundamental material descriptors for the ion-ion and ion-lattice interactions, which underpin a range of deleterious phase transitions of layered transition metal oxide electrodes for not only the Na-ion intercalation but also other beyond-Li-ion, such as K- and Ca-ion, chemistries. The fundamental contribution of this research is the identification of the material descriptors for the interactions of the layered metal oxide, which will allow for the rational design of the property and the intercalation chemistry of the layered transition metal oxides. Adopting the Na-based layered transition metal oxide as the model compound, the research will elucidate how changes in the ion-ion and the ion-lattice interactions, which is realized by varying the composition and nature of the intercalant ions, affect the layer-gliding phase transition, Na-ion/vacancy ordering, Na-ion diffusion, and the chemical and electrochemical stability of the layered oxides. These properties and processes will be characterized by a suite of complementary electrochemical, structural, and thermal analytical techniques. The outcome of this research will lead to a rational solution to overcome the barriers for the reversible Na-ion intercalation at high voltages. The practical implication is the development of “designer materials” that suppress/mitigate the deleterious phase transitions and processes in the intercalation reaction, thereby enabling high-performance energy storage materials.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.