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Real-Time Observation of Li Deposition on a Li Electrode with Operand Atomic Force Microscopy and Surface Mechanical Imaging
journal contribution
posted on 2017-02-07, 00:00 authored by Mitsunori Kitta, Hikaru SanoNanoscale investigations
of Li deposition on the surface of a Li
electrode are crucial to understand the initial mechanism of dendrite
growth in rechargeable Li-metal batteries during charging. Here, we
studied the initial Li deposition and related protrusion growth processes
at the surface of the Li electrode with atomic force microscopy (AFM)
in a galvanostatic experiment under operand condition. A flat Li-metal
surface prepared by precision cutting a Li-metal wire in electrolyte
solution (100 mM LiPF6 in propylene carbonate) was observed
with peak-force-tapping mode AFM under an inert atmosphere. During
the electrochemical deposition process of Li, protrusions were observed
to grow selectively. An adhesion image acquired with mechanical mapping
showed a specifically small contrast on the surface of growing protrusions,
suggesting that the heterogeneous condition of the surface of the
Li electrode affects the growth of Li dendrites. We propose that a
modification of the battery cell design resulting in a uniform solid–liquid
interface can contribute to the homogeneous deposition of Li at the
Li electrode during charging. Further, the mechanical mapping of Li
surfaces with operand AFM has proven to play a significant role in
the understanding of basic mechanisms of the behavior of the Li electrode.