SUBJECT: Ph.D. Dissertation Defense
BY: Marc Papakyriakou
TIME: Thursday, May 6, 2021, 3:00 p.m.
TITLE: Chemo-Mechanics of Rechargeable Battery Electrode and Electrolyte Materials by Nanoindentation
COMMITTEE: Dr. Shuman Xia, Chair (ME)
Dr. Matthew McDowell (ME/MSE)
Dr. Hailong Chen (ME)
Dr. Ting Zhu (ME)
Dr. Claudio V. Di Leo (AE)


Electric energy storage is an ever increasing area of demand in our modern world. Rechargeable batteries have thus become essential for a wide range of applications. This is due to the increase in demand for portable electronics and electric vehicles: These applications specifically require high-density batteries, as the weight and size of the battery is a limiting factor in many designs. One method for solving the problem of energy density is by utilizing novel higher capacity anode materials in alkali-ion batteries (AIBs). But high-capacity anode materials for these applications suffer from large volumetric expansions which can lead to fracture and failure, resulting in poor cyclability. Thus, understanding of their mechanical properties is a lynchpin in their applicability. In addition to higher capacity, greatly increasing reliability, cyclability, and safety are essential traits desired for any battery system. There have been examples of AIBs batteries quickly degrading with standard use and of electric vehicles experiencing thermal runaway and combusting catastrophically. For this aim, there has been interest in solid electrolytes (SEs), which would immediately reduce the risk of combustion due to their higher stability and lower flammability. But very little is known about the mechanical properties of these materials, which are relevant to SEs’ potential role in suppression of dendritic growth and their resistance to fracture if they are bonded to an electrode with large volumetric change. This thesis covers a coupled nanoindentation experimental and finite element computational approach for conducting a range of temperature dependent Nanoindentation experiments on lithiated and sodiated germanium anodes, and LLZO, LAGP, LSPS, and LPSC SEs to determine fundamental chemo-mechanical characteristics of the material systems. This increased mechanical knowledge assists in the making these SEs and high capacity battery anodes more commercially viable.