Quantifying Graphite Solid-Electrolyte Interphase Chemistry and its Impact on Fast Charging

Date Published
08/2022
Publication Type
Journal Article
Authors
DOI
10.1021/acsenergylett.2c01059
Abstract

The solid-electrolyte interphase (SEI) enables the remarkable capacity retention of lithium-ion batteries, yet a comprehensive quantitative description of the SEI composition remains elusive. Using a combination of differential electrochemical mass spectrometry and mass spectrometry titration, we quantify graphite SEI components formed under electrolytes of varying salt concentrations. We find that, regardless of salt concentration, a conversion of initially deposited lithium ethylene dicarbonate to monocarbonates (likely lithium ethylene monocarbonate) and noncarbonate species occurs, and the extent of this conversion increases with electrolyte aging. We additionally demonstrate that as the concentration increases (up to 2.0 M LiPF6), the SEI becomes progressively thinner with more LiF and less solid carbonates deposited. Finally, we reveal that less dead lithium formation and less solid carbonate deposition occur during prolonged fast charging for higher-concentration electrolytes. Because of the advantages imparted by a thinner SEI, the onset state of charge for lithium plating for the 2.0 M electrolyte is later than that predicted by a standard electrochemical model, underscoring the importance of explicit SEI effects in future electrochemical models.

Journal
ACS Energy Letters
Volume
7
Year of Publication
2022
Issue
8
Pagination
2734 - 2744
ISSN Number
2380-8195
URL
Short Title
ACS Energy Lett.
Refereed Designation
Refereed
Organizations
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