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Antisite Defects in Sol‐Gel‐Synthesized LiFePO 4 at Higher Temperature: Effect on Lithium‐Ion Diffusion
Author(s) -
Raj Hari,
Rani Sonia,
Sil Anjan
Publication year - 2018
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201800889
Subject(s) - rietveld refinement , diffusion , calcination , materials science , dielectric spectroscopy , lithium (medication) , ion , electrochemistry , analytical chemistry (journal) , electrode , chemistry , crystallography , crystal structure , chromatography , thermodynamics , medicine , biochemistry , physics , organic chemistry , endocrinology , catalysis
In the present work, the study of atomic defects in LiFePO 4 is achieved by Rietveld refinements. Several LiFePO 4 samples are synthesized by using a sol‐gel process with varying calcination times and argon flow rates. Quantitative analysis of XRD patterns through Rietveld refinements confirms 2 % antisite defects in the LiFePO 4 sample. However, for the first time, we have observed antisite defects in LiFePO 4 prepared through a sol‐gel process at a higher temperature of 700 °C. Two samples identified as LFP−A and LFP−B are further studied by electrochemical analysis and electrochemical impedance spectroscopy to examine the effect of the antisite defects on the electrochemical performances and Li‐ion diffusion of LiFePO 4 . Sample LFP−B with 2 % antisite defects shows, at 0.1 C rate, a lower discharge capacity of 138 mAh g −1 as compared to 150 mAh g −1 for LFP−A. LFP−B also shows shorter cycle life as well as rate capability at all of the C rates studied. Li‐ion diffusion coefficients of LFP−A and LFP−B in initially prepared electrodes are found to be 1.669×10 −13 and 1.198×10 −13 cm 2 s −1 , respectively, whereas the diffusion coefficients after 200 cycles are 0.968×10 −13 and 0.436×10 −13 cm 2 s −1 , respectively.