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This content will become publicly available on January 4, 2017

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

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.
 [1] ;  [2] ;  [3] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Materials Science Division
  2. Rice Univ., Houston, TX (United States). Department of Materials Science and NanoEngineering
  3. Pennsylvania State Univ., University Park, PA (United States). Dept. of Material Sciences and Engineering
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1614-6832
Grant/Contract Number:
AC52-07NA27344; SC0002626; LLNL-SR-648484; CMMI-1235092
Accepted Manuscript
Journal Name:
Advanced Energy Materials
Additional Journal Information:
Journal Volume: 6; Journal Issue: 6; Journal ID: ISSN 1614-6832
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; 29 ENERGY PLANNING, POLICY AND ECONOMY; 25 ENERGY STORAGE interfacial defects; electrode particles; microelasticity theory; phase boundary orientations; phase-field models