In Operando Multimodal Characterization of Electrode Electrolyte Interfaces for Next-Generation Energy Applications
DescriptionThe Solid Electrolyte Interphase (SEI) plays a vital role in determining the charge transfer and electrochemical kinetics, and thus the power density and stability of a battery. It is known that the SEI is electronically insulating and ionically conductive. Diffusion of cations through the SEI and spatial variation of ionic conductivity leads to non-uniform nucleation density and higher probability of dendrite formation. A uniform and compact SEI that passivates the alkali metal surface effectively prevents the exposure of fresh metal to the electrolyte; without the protective layer, the metal can react with the electrolyte leading to low coulombic efficiency. The SEI may also prevent non-uniform ionic flux induced dendritic growth. However, an unstable SEI may result in continuous “cracking” and “healing” of the layer with irreversible capacity loss. Other studies, to some extent, have revealed the composition of SEI, ion transport behavior through SEI and their dearly stages of nucleation and growth,8 but not fully understood.SEI on lithium/sodium has not been fully experimentally established and enough challenged, and fundamental understanding is still needed to definitively determine what and how species are formed on the surface, and how applied potential and cycling influence it. The development of synchrotron and in situ techniques should help find the missing pieces of the SEI puzzle. To elucidate the real growth behavior and composition of SEI, we are going to utilize three pathways to accomplish our goal, as shown in Figure 3. Pathway 1, In-situ Characterizations using 3-titanium electrodes electrochemical liquid cell; Pathway 2, Ex-situ Characterizations using 3- titanium electrodes electrochemical liquid cell; Pathway 3, Electrochemical Impedance Spectroscopy (EIS) Characterization using Swagelok T-cell. After complementary characterizations through Pathway 1, Pathway 2 and Pathway 3, we will summarize the dynamic Li metal/ Na metal deposition behavior and SEI formation, the obtained composition, structure and chemical information, and the chemical diffusion coefficients. Combine with simulation and theoretical calculations, we will propose the SEI model with new insight and understanding, which will benefit to Li/Na metal batteries, Li-air/Na-air and Li-S/Na- S batteries.
|Effective start/end date||1/10/19 → …|