(Invited) The Stability and Kinetics of the Li/Solid Electrolyte Interface

Abstract

Owing to the potential to achieve >1000 Wh/L and >400 Wh/kg while exhibiting a dramatic improvement in safety, Li-metal solid-state batteries (SSBs) are promising technology to accelerate the widespread adoption of EVs. However, their remain gaps in knowledge in understanding the mechanical and electrochemical phenomena that control the stability and kinetics of the Li/solid electrolyte (SE) interface.It is well known that Li (and Na) can penetrate ceramic and polymer solid electrolytes during charging. The term critical current density (CCD) is frequently used to determine the maximum charging rate before Li filaments penetrate. When normalized to a flat planar interface, CCDs during plating in literature range between 0.1 and 10 mA/cm2. Indeed, there is a broad range CCDs upon charging, moreover the role of pore formation during stripping has shed light on the factors that contribute Li metal penetration. In addition, factors can affect CCD such as charge passed (0.01 to 3 mAh/cm2), temperature (25 to 200 oC), pressure (0 to tens of MPa), and Li thickness (0.1 to 750 microns).In this presentation, the aspects that collectively contribute to determining the stability and kinetics of the Li/SE will be discussed. The discussion with shift the recent focus on Li penetration during charging to Li void formation at the interface during stripping in cells that use commercially relevant Li thickness (< 20 microns), “anode-free” or in-situ formed Li anodes, LLZO SE. The results of this work can help guide efforts develop Li metal SSB for use in EVs.Professor Jeff Sakamoto has 20 years of experience studying and translating ceramic materials for electrochemical materials into energy technologies for terrestrial and space applications. He was a senior researcher at the Caltech Jet Propulsion Laboratory (2000-2007), a Professor at Michigan State University (2007-2014), and has been a Professor at the University of Michigan since 2014. The Sakamoto group synthesizes ceramic electrolytes, tests their electrochemical and mechanical properties, and develops manufacturing processes for solid state batteries. Dr. Sakamoto is a Kavli Frontiers of Science Fellow, and was a chair, organizer, speaker, and delegate at the National Academy of Sciences Frontiers of Science and the National Academy of Engineering Frontiers of Engineering Symposia. Dr. Sakamoto received two Major Space Act Awards from the NASA Inventions and Contributions Board, is the primary contributor on 34 patents and received the Teacher-Scholar (2013), and Withrow Excellence in Teaching (2009) Awards at Michigan State University.