Benedek, R. and van de Walle, A. (2008) Free Energies for Acid Attack Reactions of Lithium Cobaltate. Journal of the Electrochemical Society, 155 (10). A711-A715. ISSN 0013-4651 http://resolver.caltech.edu/CaltechAUTHORS:BENjes08
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The attack of lithium-ion battery cathodes by stray aqueous HF, with resultant dissolution, protonation, and possibly other unintended reactions, can be a significant source of capacity fade. We explore the calculation of reaction free energies of lithium cobaltate in acid by a “hybrid” method, in which solid-phase free energies are calculated from first principles at the generalized gradient approximation + intrasite coulomb interaction (GGA+U) level and tabulated values of ionization potentials and hydration energies are employed for the aqueous species. Analysis of the dissolution of the binary oxides Li2O and CoO suggests that the atomic energies for Co and Li should be shifted from values calculated by first principles to yield accurate reaction free energies within the hybrid method. With the shifted atomic energies, the hybrid method was applied to analyze proton-promoted dissolution and protonation reactions of LiCoO2 in aqueous acid. Reaction free energies for the dissolution reaction, the reaction to form Co3O4 spinel, and the proton-for-lithium exchange reaction are obtained and compared to empirical values. An extension of the present treatment to consider partial reactions is proposed, with a view to investigating interfacial and environmental effects on the dissolution reaction.
|Additional Information:||©2008 The Electrochemical Society. (Revised 12 May 2008; published 30 July 2008) We are most grateful to M.M. Thackeray for his guidance and encouragement. This work was supported by the Office of Freedom-Car and Vehicle Technologies (Batteries for Advanced Transportation Technologies Program), U.S. Department of Energy, under contract no. W31-109-Eng-38. A. van de Walle was supported by the National Science Foundation through TeraGrid computing resources provided by NCSA and SDSC under grant DMR060011N. Grants of computer time at the National Energy Research Supercomputer Center, Lawrence Berkeley Laboratory, are gratefully acknowledged. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (Argonne). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under contract no. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. Argonne National Laboratory assisted in meeting the publication costs of this article.|
|Subject Keywords:||ab initio calculations; association; chemical exchanges; dissolving; electrochemical electrodes; electrochemistry; free energy; ionisation potential; lithium compounds; secondary cells; solvation; thermochemistry|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||06 Aug 2008 22:49|
|Last Modified:||26 Dec 2012 10:12|
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