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Title: Lithium Self-Discharge and Its Prevention: Direct Visualization through In Situ Electrochemical Scanning Transmission Electron Microscopy

To understand the mechanism that controls low-aspect-ratio lithium deposition morphologies for Li-metal anodes in batteries, we conducted direct visualization of Li-metal deposition and stripping behavior through nanoscale in situ electrochemical scanning transmission electron microscopy (EC-STEM) and macroscale-cell electrochemistry experiments in a recently developed and promising solvate electrolyte, 4 M lithium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane. In contrast to published coin cell studies in the same electrolyte, our experiments revealed low Coulombic efficiencies and inhomogeneous Li morphology during in situ observation. In addition, we conclude that this discrepancy in Coulombic efficiency and morphology of the Li deposits was dependent on the presence of a compressed lithium separator interface, as we have confirmed through macroscale (not in the transmission electron microscope) electrochemical experiments. Our data suggests that cell compression changed how the solid-electrolyte interphase formed, which is likely responsible for improved morphology and Coulombic efficiency with compression. Furthermore, during the in situ EC-STEM experiments, we observed direct evidence of nanoscale self-discharge in the solvate electrolyte (in the state of electrical isolation). This self-discharge was duplicated in the macroscale, but it was less severe with electrode compression, likely due to a more passivating and corrosion-resistant solid-electrolyte interphase formed in the presence of compression. By combiningmore » the solvate electrolyte with a protective LiAl 0.3S coating, we show that the Li nucleation density increased during deposition, leading to improved morphological uniformity. In conclusion, self-discharge was suppressed during rest periods in the cycling profile with coatings present, as evidenced through EC-STEM and confirmed with coin cell data.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [2] ;  [3] ; ORCiD logo [4] ;  [5]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Joint Center for Energy Storage Research and Nanoscale Sciences
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Joint Center for Energy Storage Research; Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). MESA Fabrication Operations
  4. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Joint Center for Energy Storage Research; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Energy & Environmental Directorate
  5. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Joint Center for Energy Storage Research and Center for Integrated Nanotechnologies
Publication Date:
Report Number(s):
SAND-2017-12954J; SAND-2018-1499J
Journal ID: ISSN 1936-0851; 659164; TRN: US1800254
Grant/Contract Number:
AC04-94AL85000; SC0001160; NA0003525
Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 11; Journal Issue: 11; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Energy Frontier Research Centers (EFRC) (United States). Nanostructures for Electrical Energy Storage (NEES)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE; artificial solid-electrolyte interphase; electrochemical transmission electron microscopy; lithium-ion batteries; lithium-metal anode; mechanical compression; protective coating; solid-electrolyte interphase
OSTI Identifier:
1426804
Alternate Identifier(s):
OSTI ID: 1411618