Issue 8, 2024

Reversible interfacial Li-oxide formation on germanium and silicon anodes revealed by time-resolved microgravimetry

Abstract

Germanium has received recent attention as a promising candidate for the next generation of Li-ion anodes due to its high capacity, higher conductivity, and faster lithium-ion diffusivity relative to silicon. However, the uncertainty in the Li-storage mechanism and the formation of a solid electrolyte interface (SEI) has hampered its further development. Herein, operando microgravimetry on the Ge electrode has been conducted to determine the SEI mass (irreversibly deposited) and to distinguish it from the reversibly cycled species, and their individual contributions to the total capacity. From the obtained time-resolved mass spectra, determined by correlating gravimetry and charge flux, Li2O along with Li is identified as a reversibly cycled species, contributing significantly to the electrochemical capacity. The amount of this cycled Li2O depends on (i) the cycling rate and (ii) the thickness of the anode. Interestingly, the amount of Li2O decreases if pronounced anode cracking appears. A direct comparison between Si and Ge indicates that the amount of the reversible Li2O is predominantly controlled by the diffusivity of lithium into the electrodes. The study provides a general mechanism for balancing the interfacial and bulk storage of Li in the form of an oxide or by alloying, respectively.

Graphical abstract: Reversible interfacial Li-oxide formation on germanium and silicon anodes revealed by time-resolved microgravimetry

Supplementary files

Article information

Article type
Paper
Submitted
18 Sep 2023
Accepted
16 Jan 2024
First published
18 Jan 2024
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2024,12, 4610-4622

Reversible interfacial Li-oxide formation on germanium and silicon anodes revealed by time-resolved microgravimetry

K. Wang, Y. Joshi, T. Kohler, M. Mead and G. Schmitz, J. Mater. Chem. A, 2024, 12, 4610 DOI: 10.1039/D3TA05641D

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