In situ real-time gravimetric and viscoelastic probing of surface films formation on lithium batteries electrodes

Vadim Dargel,Prasant Nayak,Mikhael D Levi,Sergey Sigalov,Leonid Daikhin,Netanel Shpigel,Doron Aurbach

doi:10.1038/s41467-017-01722-x

Vadim Dargel, Prasant Nayak + Show 5 more

Open Access

https://doi.org/10.1038/s41467-017-01722-x

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Journal: Nature Communications	Publication Date: Nov 9, 2017
Citations: 74	License type: open-access

Affiliation: Bar-Ilan University, Tel Aviv University

Abstract

It is generally accepted that solid–electrolyte interphase formed on the surface of lithium-battery electrodes play a key role in controlling their cycling performance. Although a large variety of surface-sensitive spectroscopies and microscopies were used for their characterization, the focus was on surface species nature rather than on the mechanical properties of the surface films. Here we report a highly sensitive method of gravimetric and viscoelastic probing of the formation of surface films on composite Li4Ti5O12 electrode coupled with lithium ions intercalation into this electrode. Electrochemical quartz-crystal microbalance with dissipation monitoring measurements were performed with LiTFSI, LiPF6, and LiPF6 + 2% vinylene carbonate solutions from which structural parameters of the surface films were returned by fitting to a multilayer viscoelastic model. Only a few fast cycles are required to qualify surface films on Li4Ti5O12 anode improving in the sequence LiPF6 < LiPF6 + 2% vinylene carbonate << LiTFSI.

Highlights

It is generally accepted that solid–electrolyte interphase formed on the surface of lithiumbattery electrodes play a key role in controlling their cycling performance
We have developed a highly sensitive EQCM-D-based methodology for in situ assessment of gravimetric and viscoelastic changes in composite LTO electrodes caused by simultaneous Liion insertion/extraction and the formation/growth of solid–electrolyte interphase (SEI) on their surfaces in three different Li-battery electrolyte solutions
The model selectively characterizes the mechanical state of each layer in the multilayer composite electrodes assembly in contact with the electrolyte solution

Summary

Introduction

It is generally accepted that solid–electrolyte interphase formed on the surface of lithiumbattery electrodes play a key role in controlling their cycling performance. Significant consumption of active Li-ions from the electrodes during cycling (i.e., capacity fading) and deterioration of the electrodes rate capability (via a decrease in ion conduction) takes place during their cycling It is important, from the fundamental and practical points of view, to develop continuous in situ probing of the electrical and mechanical “state-of-health” of the forming SEI in battery electrodes in contact with various electrolyte solutions under diverse cycling conditions. We have chosen for this study highly important challenge: understanding of the surface response of Li4Ti5O12 electrodes denoted as LTO These electrodes which redox potential is relatively high (1.5 V vs Li) are considered as very stable and fast anodes for Li-ion batteries, in applications requiring very prolonged cycling (e.g., load leveling)[3]. EQCM-D was recently used for a detailed study of the properties of surface films formed on Sn metallic films and a composite electrode during their lithiation in aprotic solutions[7,9,13,40]

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