title: Lithium Electrodeposition Dynamics in Aprotic Electrolyte Observed in Situ via Transmission Electron Microscopy.
abstract: Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm(2) leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effect of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. We discuss the implications for operando STEM liquid-cell imaging and Li-battery applications.
authors.affiliation: Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Leenheer
authors.affiliation: Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Jungjohann
authors.affiliation: Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Zavadil
authors.affiliation: Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
authors.forename: John P
authors.initials: JP
authors.lastname: Sullivan
authors.affiliation: Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
authors.forename: C Thomas
authors.initials: CT
authors.lastname: Harris
keywords: electron beam radiolysis; in situ TEM; liquid-cell electron microscopy; lithium electrodeposition; lithium-ion battery; solid electrolyte interphase