ERI: Interphase Evolution and Electrochemical Behavior for Highly Reversible Zinc Metal Anodes

Although lithium-ion batteries have been widely used for a wide range of applications ranging from electric vehicles to grid storage of renewable electricity, the high cost and limited domestic supply of lithium and transition metal (e.g. cobalt) resources necessitate the development of aqueous rechargeable zinc metal batteries as a “beyond-lithium” complementary technology. However, unwanted reactions occur on the region between zinc metal anode and electrolytes, which compromises the lifetime and durability of aqueous zinc batteries. To improve the cell lifetime, it is important to understand the relationship between the area between the anode and the electrode, the interphase region, and the electrochemical performance of zinc metal anode prior to the design stages. In this Engineering Research Initiation (ERI) project, the PI and his research group will study the evolution of this interphase and its effect on the zinc anode performance during cell operation. The project will provide critical scientific knowledge to develop advanced aqueous batteries for maintaining and advancing US battery technology leadership. The multidisciplinary research project will provide ample educational and outreach opportunities for high school, undergraduate, M.S. and Ph.D. students, including those from underrepresented groups in STEM. This ERI research project seeks to advance fundamental knowledge of the aqueous solid electrolyte interphase (SEI) evolution driven by SEI defects and an electron approachable thickness. A close integration of experimental and modeling approaches based on pyrazole-based containing aqueous electrolytes will be used to study key factors that impact SEI formation and to confirm the effect of the SEI’s defects and thickness. Other unique elements of the research project include 1) identifying the morphology and chemical compositions of zinc anode SEI as a function of aqueous pH value, temperature and cell cycling time using surface characterizations, 2) determining the mechanism of Zn2+ cation transport through the SEI using electrochemical impedance spectroscopy and density functional theory (DFT) calculations in addition to SEI morphology and chemical information, 3) identifying the dependence of zinc metallic dendrite formation/growth and mechanical degradation of the SEI on the cycling history using scanning electron microscopy, nanoindentation and a coupled electrochemical-mechanical multiphysics modeling framework, and 4) identifying the favorable reaction pathways of aqueous SEI formation/evolution using DFT calculations combined with the electro−chemo−mechanical information of the SEI obtained in the first three tasks. Through this project, the PI will catalyze new research partnerships (both with internal and external collaborators) and extend the research group’s capabilities in both theoretical modeling and advanced characterization. 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.