NSF-DFG CONFINE: In-Situ Analysis of Li Transport Through Solid State Interfacial Systems by Neutron Reflectometry Measurements

DFG form 53.01 – 09/22 page 1 of max.8 Project Description – Project Proposals Erwin Hüger, Clausthal-Zellerfeld, Germany Fuqian Yang, Lexington, Kentucky, USA NSF-DFG MISSION: In-situ analysis of Li transport through solid state interfacial systems by neutron reflectometry measurements Project Summary Atomic transport through interface dominated materials like nano-scaled multilayer systems (MLSs) is relevant to many technological branches spanning from drug release in pharmaceutics, over quantum technology, to energy storage devices. Understanding the rate mechanisms responsible for anomalous atomic transport through the interfacial systems has a significant impact on the applications of nano-scaled MLSs. The objectives of this project are 1) to develop in-situ measurement technique of neutron reflectometry (NR) for the temperature ramping experiments, and operando NR to investigate the mechanisms controlling anomalous Li+ transport in MLSs with nano-sized layers, and 2) to numerically elaborate the effects of mechanical stress and space charge zones on the anomalous Li+ transport in MLSs with nano- sized layers. A closely coupled experimental and modelling approach will be used to accomplish the objectives. Specific tasks outlined in this project to achieve the objectives are: • Perform in-situ neutron reflectometry measurements during temperature ramping experiments to investigate the influence of the thicknesses of silicon and Li3NbO4 layers on the Li permeation through the interfaces and silicon layers of nano-scaled Si/Li3NbO4 MLSs. • Perform in-situ I-V measurements to characterize space charge zones by flooding the MLSs with electrons. This may neutralize the formerly electrified interfaces and/or electrified layers. • Perform electrochemical Li+ insertion in the MLSs in an electrochemical cell by flooding the Si/Li3NbO4 MLSs with additional Li+ ions. The electrochemical experiments are escorted with operando NR measurement. • Perform electrochemical cycling of LIB cells with the MLSs as LIB anode to examine if there is a correlation between the results from the kinetic investigation (the accelerated Li permeation) and the rate capability and long-term cycling ability of the MLSs. • To develop and parameterize physical models that can quantitatively analyze and predict the dependence of Li+ transport on mechanical stress and space charge zones imposed by interfaces and elucidate the rate mechanisms controlling anomalous atomic motion through interfacial systems of nano-scaled multilayer systems. The proposed research project will provide a feasible approach to in-situ investigate atomic transport through the interfacial systems of MLSs with nano-sized layers and advance the understanding of the mechanisms responsible for anomalous atomic transport in nano-scaled multilayer systems. Uncovering the effects of mechanical stress and space charge zones on atomic transport in MLSs with nano-sized layers will lead to the ultimate goal of the synthetic control of the structures of nano-scaled multilayer systems for applications in pharmaceutics, quantum technology and energy storage devices.