# Solid Electrolyte Interphase and Interface Effect on the Nucleation of Lithium Pitting

## TL;DR

This study explores how the solid electrolyte interphase and interface charge transfer affect lithium pitting during battery operation.

## Contribution

The paper decouples the effects of SEI and interfacial charge transfer on lithium pitting nucleation mechanisms.

## Key findings

- Ether electrolytes produce larger and sparser pits under galvanostatic stripping due to lower stripping overpotential.
- Potentiostatic stripping in ether electrolytes results in smaller pits with higher nucleation density due to faster kinetics.
- SEI and interfacial charge transfer significantly influence pitting nucleation modes and battery performance.

## Abstract

The nucleation of
pits and their evolution on the lithium (Li)
metal anode greatly impact the cyclability and safety of Li–metal
batteries. Overpotential has been found to be inversely related to
the Li pit radius and exponentially related to the nucleation rate.
However, it remains unclear how the electrode/electrolyte interphase
and interface impact the nucleation of pitting. In this study, we
decouple the electrolyte effect into a solid electrolyte interphase
(SEI) and interface charge transfer (CT). Under galvanostatic stripping,
ether electrolytes yield larger and sparser pits than the carbonate
electrolyte, which is related to the lower stripping overpotential
of ether electrolytes. Under potentiostatic stripping, a smaller pit
size and higher nucleation density have been revealed in ether electrolytes
due to the higher nucleation rate. We found that charge-transfer kinetics
on the interface of the Li-metal anode will greatly influence its
nucleation mode and kinetics. Slow charge-transfer kinetics in the
carbonate electrolyte lead to a lower nucleation rate and larger Li
pits, which are close to 3D nucleation. In ether electrolytes with
fast charge transfer kinetics, the pitting process exhibits 2D nucleation.
The SEI derived from various electrolytes mainly influences the stripping
overpotential and the morphology of the pits. By clarifying the roles
of SEI and interfacial charge transfer on the nucleation of pitting,
this work will greatly benefit the design of cycling profiles and
electrolyte recipes for next-generation Li-metal batteries.