Nondestructive Detection of Li Dendrites inside Li-ion Batteries via Plasmonic Resonance

Lithium-ion batteries are the most widely used portable energy devices. However, there are intrinsic limitations of current lithium-ion batteries, such as safety, insufficient energy density, and short cycle life. In particular, lithium dendrite growth is one of the most serious problems because it can cause an explosion or fire by forming short circuits inside a battery cell. It is essential to understand its mechanism, and effective monitoring will be the first step to tackle the problem. However, many ex-situ characterizations up to this point require opening cycled battery cells and sample preparation, which inevitably alter the original structures of the cells. In this project, we will develop a nondestructive, in-situ diagnostic tool to probe lithium dendrites formed inside lithium-ion batteries using optical spectroscopic ellipsometry. Our idea is to detect the plasmonic resonance of lithium dendrites inside battery cells using optical spectroscopy, before forming any short circuits. The detailed analysis of plasmonic resonance spectra will provide information not only on the formation of lithium dendrites but also their quantitative data such as volume fractions and lengths. We will form active collaborations between PI and Co-I, who have complementary expertise. We will acquire an understanding of the dynamics of lithium dendrites near the interface between the electrolyte and the negative electrode. Our nondestructive in-situ monitoring approach will provide useful guidance for advancing the next-generation lithium-ion battery technology. Based on the preliminary results acquired from this project, we will also pursue long-term grants from federal funding agencies such as the Department of Energy.