Defects, Entropy, and the Stabilization of Alternative Phase Boundary Orientations in Battery Electrode Particles

Tae Wook Heo, Ming Tang, Long Qing Chen, Brandon C. Wood

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Using a novel statistical approach that efficiently explores the space of possible defect configurations, the 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. This understanding can be generalized to the chemomechanics of other defective solid phase boundaries.

Original languageEnglish (US)
Article number1501759
JournalAdvanced Energy Materials
Volume6
Issue number6
DOIs
StatePublished - Mar 23 2016

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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