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Title: Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate

Olivine lithium iron phosphate is a technologically important electrode material for lithium-ion batteries and a model system for studying electrochemically driven phase transformations. Despite extensive studies, many aspects of the phase transformation and lithium transport in this material are still not well understood. Here we combine operando hard X-ray spectroscopic imaging and phase-field modeling to elucidate the delithiation dynamics of single-crystal lithium iron phosphate microrods with long-axis along the [010] direction. Lithium diffusivity is found to be two-dimensional in microsized particles containing ~3%lithium-iron anti-site defects. Our study provides direct evidence for the previously predicted surface reaction-limited phase-boundary migration mechanism and the potential operation of a hybrid mode of phase growth, in which phase-boundary movement is controlled by surface reaction or lithium diffusion in different crystallographic directions. These findings uncover the rich phase-transformation behaviors in lithium iron phosphate and intercalation com-pounds in general and can help guide the design of better electrodes.
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [3] ;  [4] ;  [5] ; ORCiD logo [5] ;  [5] ;  [1] ;  [3] ;  [4] ; ORCiD logo [5] ; ORCiD logo [1]
  1. Rice Univ., Houston, TX (United States). Dept. of Materials Science & NanoEngineering
  2. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry; Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials Science & Engineering
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). Photon Science Division
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials Science & Engineering
  5. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry
Publication Date:
Report Number(s):
BNL-203492-2018-JAAM
Journal ID: ISSN 2041-1723
Grant/Contract Number:
SC0012704; DMR-1106184; DMR-1508558; SC0002626; SC0014435; AC02-98CH10886; AC02-06CH11357; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 25 ENERGY STORAGE
OSTI Identifier:
1436250