Li ion diffusivity and rate performance of the LiFePO4 modified by Cr doping

Chang Kyoo Park, Sung Bin Park, Ho Chul Shin, Won Il Cho, Ho Jang

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

This study reports the root cause of the improved rate performance of LiFePO4 after Cr doping. By measuring the chemical diffusion coefficient of lithium (DLi) using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the correlation between the electrochemical performance of LiFePO4 and Li diffusion is acquired. The diffusion constants for LiFePO4/C and LiFe0.97Cr 0.03PO4/C measured from CV are 2.48 × 10 -15 and 4.02 × 10-15 cm2 s-1, respectively, indicating significant increases in diffusivity after the modification. The difference in diffusivity is also confirmed by EIS and the DLi values obtained as a function of the lithium content in the cathode. These results suggest that Cr doping facilitates Li ion diffusion during the charge-discharge cycles. The low diffusivity of the LiFePO 4/C leads to the considerable capacity decline at high discharge rates, while high diffusivity of the LiFe0.97Cr0.03PO 4/C maintains the initial capacity, even at high C-rates.

Original languageEnglish
Pages (from-to)191-195
Number of pages5
JournalBulletin of the Korean Chemical Society
Volume32
Issue number1
DOIs
Publication statusPublished - 2011 Jan 20

Keywords

  • Chemical diffusion coefficient
  • Cyclic voltammetry
  • Doping
  • Electrochemical impedance spectroscopy
  • Lithium iron phosphate

ASJC Scopus subject areas

  • Chemistry(all)

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