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Interfacial Chemistry Effects in the Electrochemical Performance of Silicon Electrodes under Lithium-Ion Battery Conditions

journal contribution
posted on 2024-05-03, 00:34 authored by X Xu, D Martín-Yerga, NE Grant, G West, SL Pain, Minkyung KangMinkyung Kang, M Walker, JD Murphy, PR Unwin
AbstractUnderstanding the solid electrolyte interphase (SEI) formation and (de)lithiation phenomena at silicon (Si) electrodes is key to improving the performance and lifetime of Si‐based lithium‐ion batteries. However, these processes remain somewhat elusive, and, in particular, the role of Si surface termination merits further consideration. Here, scanning electrochemical cell microscopy (SECCM) is used in a glovebox, followed by secondary ion mass spectrometry (SIMS) at identical locations to study the local electrochemical behavior and associated SEI formation, comparing Si (100) with a native oxide layer (SiOx/Si) and etched with hydrofluoric acid (HF‐Si). HF‐Si shows greater spatial electrochemical heterogeneity and inferior lithiation reversibility than SiOx/Si. This is attributed to a weakly passivating SEI and irreversible lithium trapping at the Si surface. Combinatorial screening of charge/discharge cycling by SECCM with co‐located SIMS reveals SEI chemistry as a function of depth. While the SEI thickness is relatively independent of the cycle number, the chemistry – particularly in the intermediate layers – depends on the number of cycles, revealing the SEI to be dynamic during cycling. This work serves as a foundation for the use of correlative SECCM/SIMS as a powerful approach to gain fundamental insights on complex battery processes at the nano‐ and microscales.

History

Journal

Small

Volume

19

Article number

2303442

Pagination

1-10

Location

London, Eng.

ISSN

1613-6810

eISSN

1613-6829

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

40

Publisher

Wiley