Elucidating Lithium Alloying-Induced Degradation Evolution in High-Capacity Electrodes

Source

UAH PRC Research Database

Document Type

Article

Publication Title

American Chemical Society

Abstract

Alloy electrode materials offer high capacity in lithium-ion batteries; however, they exhibit rapid degradation resulting in particle disintegration and electrochemical performance decay. In this study, the evolution of lithium alloying-induced degradation due to electrochemomechanical interactions is examined based on a multipronged electrochemical and microstructural analysis. Copper-tin (Cu 6 Sn 5 ) is chosen as an exemplary alloy electrode material. Electrodes with compositional variations were fabricated, and electrochemical performance was examined under varying conditions including voltage window, C-rate, and short- and long-term cycling. Morphology and composition analyses of pristine and cycled electrodes were conducted using micrography and spectroscopy techniques. Alloying-induced electrode microstructural evolution was probed using X-ray microtomography. The rapid capacity fading was found to be caused by mechanical degradation of the electrode. Driving the electrode to a lower potential (E ≈ 0.2 V vs Li/Li + ) induced Li-Sn alloy formation and provided the characteristic large capacity; however, this led to a large volume expansion and active particle cracking and disintegration. Copper expulsion was found to be a consequence of the alloy formation; however, it was not the primary contributor to the dramatic electrochemical performance decay.

First Page

563

Last Page

577

DOI

https://doi.org/10.1021/acsami.8b14242

Publication Date

12-11-2018

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