Defects, Entropy, and the Stabilization of Alternative Phase Boundary Orientations in Battery Electrode Particles [electronic resource].

Published: Washington, D.C. : United States. Dept. of Energy, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description: Article numbers 1,501,759 : digital, PDF file
Additional Creators: Lawrence Berkeley National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary

Using a novel statistical approach that efficiently explores the space of possible defect configurations, our present study investigates the chemomechanical coupling between interfacial structural defects and phase boundary alignments within phase-separating electrode particles. Applied to the battery cathode material LiXFePO4 as an example, the theoretical analysis reveals that small, defect-induced deviations from an ideal interface can lead to dramatic shifts in the orientations of phase boundaries between Li-rich and Li-lean phases, stabilizing otherwise unfavorable orientations. Significantly, this stabilization arises predominantly from configurational entropic factors associated with the presence of the interfacial defects rather than from absolute energetic considerations. The specific entropic factors pertain to the diversity of defect configurations and their contributions to rotational/orientational rigidity of phase boundaries. Comparison of the predictions with experimental observations indicates that the additional entropy contributions indeed play a dominant role under actual cycling conditions, leading to the conclusion that interfacial defects must be considered when analyzing the stability and evolution kinetics of the internal phase microstructure of strongly phase-separating systems. Possible implications for tuning the kinetics of (de)lithiation based on selective defect incorporation are discussed. Ultimately, this understanding can be generalized to the chemomechanics of other defective solid phase boundaries.

Report Numbers

E 1.99:llnl-jrnl--673242
llnl-jrnl--673242

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Published through SciTech Connect.
01/04/2016.
"llnl-jrnl--673242"
Advanced Energy Materials 6 6 ISSN 1614-6832 AM
Tae Wook Heo; Ming Tang; Long-Qing Chen; Brandon C. Wood.

Funding Information

AC52-07NA27344
SC0002626
LLNL-SR-648484
CMMI-1235092

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