Title: Quantifying lithium concentration gradients in the graphite electrode of Li-ion cells using operando energy dispersive X-ray diffraction

Abstract

Safe, fast, and energy efficient cycling of lithium ion batteries is desired in many practical applications. However, modeling studies predict steep Li⁺ ion gradients in the electrodes during cycling at the higher currents. Such gradients introduce heterogeneities in the electrodes, which make it difficult to predict cell lifetimes as different portions of the cell age at different rates. There is a dearth of experimental methods to probe these concentration gradients across the depth of the electrode. Here we use spatially resolved energy dispersive X-ray diffraction to obtain a “movie” of lithiation and delithiation in different sections of the cell and quantify lithium gradients that develop in a porous graphite electrode during cycling at a 1C rate. Inhomogeneity in the total Li content, and in the individual ordered Li_xC₆ phases formed during lithium insertion into (and extraction from) the graphite, has been observed in an operando fashion. The complex dynamics of lithium-staging in graphite with the distinct front propagation of phase changes have been characterized and new features of these dynamics are highlighted here. As large Li⁺ ion gradients contribute to cell polarization, our results suggest that Li plating conditions can be met near the graphite electrode surface, even when themore » cell is charged at a moderate (1C) rate.« less

Authors:

Yao, Koffi P. C.  ^[1];

• Search DOE PAGES for author "Yao, Koffi P. C."
• Search DOE PAGES for ORCID "0000-0003-4310-4347"

Okasinski, John S.  ^[2];

• Search DOE PAGES for author "Okasinski, John S."
• Search DOE PAGES for ORCID "0000-0001-9056-0623"

Kalaga, Kaushik  ^[3];

• Search DOE PAGES for author "Kalaga, Kaushik"
• Search DOE PAGES for ORCID "0000-0003-4355-4102"

Shkrob, Ilya A.  ^[3];

• Search DOE PAGES for author "Shkrob, Ilya A."
• Search DOE PAGES for ORCID "0000-0002-8851-8220"

Abraham, Daniel P.  ^[3]

• Search DOE PAGES for author "Abraham, Daniel P."
• Search DOE PAGES for ORCID "0000-0003-0402-9620"

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+ Show Author Affiliations

1. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, USA, University of Delaware
2. Advanced Photon Source, Argonne National Laboratory, Argonne, USA
3. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, USA

Publication Date:

Wed Feb 13 00:00:00 EST 2019

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)

OSTI Identifier:

1490116

Alternate Identifier(s):

OSTI ID: 1509908

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Published Article

Journal Name:

Energy & Environmental Science

Additional Journal Information:

Journal Name: Energy & Environmental Science Journal Volume: 12 Journal Issue: 2; Journal ID: ISSN 1754-5692

Publisher:

Royal Society of Chemistry (RSC)

Country of Publication:

United Kingdom

Language:

English

Subject:

25 ENERGY STORAGE; fast charge; graphite staging; lithium plating; phase heterogeneity; radiography