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Title: The Nature of Electrochemical Delithiation of Li-Mg Alloy Electrodes: Neutron Computed Tomography and Modeling of Li Diffusion and Delithiation Phenomenon

Li-Mg alloys are promising as positive electrodes (anodes) for Li-ion batteries due to the high Li storage capacity and the relatively lower volume change during the lithiation/delithiation process. They also present a unique opportunity to image the Li distribution through the electrode thickness at various delithiation states. In this work, spatial distributions of Li in electrochemically delithiated Li-Mg alloy electrodes have been quantitatively determined using neutron tomography. Specifically, the Li concentration profiles along thickness direction are determined. A rigorous analytical model to quantify the diffusion-controlled delithiation, accompanied by phase transition and boundary movement, has also been developed to explain the delithiation mechanism. The analytical modeling scheme successfully predicted the Li concentration profiles which agreed well with the experimental data. It is demonstrated that during discharge Li is removed by diffusion through the solid solution Li-Mg phases and this proceeds with β→α phase transition and the associated phase boundary movement through the thickness of the electrode. This is also accompanied by electrode thinning due to the change in molar volume during delithiation. In conclusion, following the approaches developed here, one can develop a rigorous and quantitative understanding of electrochemical delithiation in electrodes of electrochemical cells, similar to that in the presentmore » Li-Mg electrodes.« less
Authors:
 [1] ;  [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [3]
  1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Metallurgical Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Data Analysis and Visualization Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 2; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE; Analytical model; Diffusion; Li-Mg alloy; Lithium-ion batteries; Neutron tomography
OSTI Identifier:
1393861