In situ⁷Li-NMR analysis of lithium metal surface deposits with varying electrolyte compositions and concentrations

Abstract

A combined study of SEM, in situ7Li-NMR spectroscopy, and electrochemical investigations is applied to in detail elucidate the lithium deposition phenomena of symmetrical Li‖Li cells containing varying electrolyte compositions and concentrations.

Solid Electrolyte Interphase Evolution on Lithium Metal Electrodes Followed by Scanning Electrochemical Microscopy Under Realistic Battery Cycling Current Densities

“…The experimental galvanostatic charging-discharging profiles measured directly in this symmetrical cell against an independent Li/Li + reference electrode with 1 M LiClO 4 in propylene carbonate at integral current densities of 0.7 mA/ cm 2 , 1.4 mA/cm 2 , and 2.8 mA/cm 2 show overpotentials of 0.2 V, 0.28 V and 0.38 V (Figure 3), respectively, which is within the range of reported overpotentials at Li metal electrodes in laboratory cells. [20] As reported before, there are slightly different overpotentials for the galvanostatic charging and discharging of the Li metal electrode. [10] The electrolyte was selected as the low vapor pressure of propylene carbonate is advantageous for O 2 jjLi cells and ClO 4 is less sensitive to moisture than for instance PF 6…”

Stabilizing Effect of Polysulfides on Lithium Metal Anodes in Sparingly Solvating Solvents

“…The presence of inhomogeneous microstructure is indicated by NMR resonances at 260 and 270 ppm or even higher [46,47] . 1.5 M LiTFSI in TMS/TTE (1 : 1) with and without PS were used as model electrolytes for comparison.…”

“…Afterwards, 200 μl electrolyte was filled in and the last side was then sealed under vacuum. The set‐up was adapted according to earlier publications [46,50] . Before assembling, the lithium foil was roll‐pressed from 500 μm to 300 μm thickness between two siliconized biaxial‐oriented polyethylene terephthalate (boPET) foils with a roll press (Hohsen Corp., HSAM‐615H) in order to smooth the surface.…”

Wetting Phenomena and their Effect on the Electrochemical Performance of Surface‐Tailored Lithium Metal Electrodes in Contact with Cross‐linked Polymeric Electrolytes

“…During electrodeposition/electrodissolution, such interphases and surface topographies are further altered and partially rebuilt, resulting in complex and dynamic surface conditions . Li electrodeposition is also accompanied by the formation of so‐called high‐surface‐area Li (HSAL) which in turn is being formed as a result of uncontrolled accumulation of Li deposits . Safety concerns regarding such hazardous HSAL formation and a possible cascade of unwanted reactions with flammable electrolyte components are presumed .…”