CAS: Controlling Solid Electrolyte Interphases using Organometallic Electrolyte Additives

University Of Illinois At Chicago, Chicago IL

Investigators

Abstract

With support from the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Neal Mankad of the Department of Chemistry at the University of Illinois-Chicago is developing new organometallic complexes to serve as additives in battery electrolytes. The goal of this research is to exploit the ability of small loadings of these compounds to influence the chemistry at anode surfaces, with the ultimate goal of improving long-term cycling stability and operational safety of high-density batteries such as those with lithium metal anodes. The project lies at the interface of organometallic chemistry, electrochemistry, and battery design and is, therefore, well suited to the education of scientists at all levels. This team is also well positioned to provide education and training for students underrepresented in science. Outreach activities involving science coaching of Chicago-area high school students will also be part of the project. The project is based on preliminary data obtained by the team showing that quadruply-bonded dimolybdenum(II) complexes supported by 2-(2-methoxyethoxy)acetate ligands reversibly bind lithium ions in the second coordination sphere, inducing aggregation of cationically charged coordination oligomers that self-assemble onto the anode surface in electrochemical cells. Upon deposition, the modified electrodes are found to have significantly modified compositions at the solid-electrolyte interphases and display measurably different lithium plating and stripping behaviors compared to control systems lacking the dimolybdenum additive. This project aims to address three questions: (i) What is the mechanism of the observed behavior under lithium metal battery cycling conditions? (ii) How does the behavior change when the organometallic additive structure is varied to modulate the lithium ion binding constant and/or reduction potential? (iii) Does this behavior extend to “beyond lithium” technologies such as sodium and magnesium metal batteries? If successful, these research studies will likely have broad scientific impact on electrochemical cell/battery design, performance and sustainability. 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.