CAS: Understanding the Role of External Constraint on Electrochemical (De)alloying Mechanisms

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

NON-TECHNICAL DESCRIPTION Solid-state batteries offer the potential for more energy and greater safety compared to conventional lithium-ion batteries. However, the reaction behavior of materials used for lithium ion storage within solid-state batteries must be understood and better controlled for improved battery performance. A variety of metals can react with and store lithium ions within solid-state batteries, but their dynamic reaction behavior when entirely surrounded by and constrained by other solid materials is largely unknown. This research uses a variety of experimental techniques designed to reveal reaction processes of lithium metal alloys under various degrees of mechanical constraint and relate this to electrochemical behavior. The new knowledge created through this research is important for advancing the current state-of-the-art in energy storage technologies. This research is being carried out by graduate student researchers, who are being trained in the science of materials for energy storage. Additionally, this project also includes a collaboration with a K-12 teacher to develop materials science curriculum related to batteries for use in their classroom. TECHNICAL DESCRIPTION Metals that electrochemically alloy/dealloy with lithium often exhibit high lithium storage capacity. Because of the large volume changes exhibited by alloy materials during electrochemical reactions, mechanical constraint at different length scales likely plays an important role in the transformation behavior of particulate alloy materials. However, the effect of mechanical constraint on alloy/dealloying reactions is not well understood. The overall objective of this research is to understand how external mechanical constraint affects and controls internal reaction mechanisms across length scales during electrochemical alloying/dealloying of metal particles for solid-state batteries. These systems inherently exhibit mechanical confinement due to their all-solid nature. This research uses in situ and ex situ imaging methods, real-time stress measurement during electrochemical cycling, and other electrochemical assessments. Together, these techniques clarify how constraint exerted by surface coating layers and surrounding materials affect morphological evolution and electrochemical behavior during alloying and dealloying of metal particles with lithium. This research provides new understanding of solid-state alloying/dealloying processes, which is critical for developing these materials as electrodes for solid-state batteries. 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.