Enhanced charge-transfer kinetics by anion surface modification of LiFePO4

Kyu Sung Park, Penghao Xiao, So Yeon Kim, Anthony Dylla, Young Min Choi, Graeme Henkelman, Keith J. Stevenson, John B. Goodenough

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)

Abstract

Despite the great achievement in understanding the materials properties and powder engineering of LiFePO4, the chemical bonding at the surface has been almost ignored. Herein, we demonstrate that the undercoordinated Fe2+/Fe3+ redox couple at the surface gives a high barrier for charge transfer, but it can be stabilized by nitrogen or sulfur adsorption. The surface modification improves greatly the charge transfer kinetics and the charge/discharge performance of a LiFePO4 cathode. Density functional theory (DFT) calculation estimates the origin of the improvement in terms of an electronic and ionic contribution based on a surface model probed by time of flight secondary ion mass spectrometry (TOF-SIMS); the calculation agrees well with an experimental rate-constant analysis.

Original languageEnglish
Pages (from-to)3212-3218
Number of pages7
JournalChemistry of Materials
Volume24
Issue number16
DOIs
Publication statusPublished - 28 Aug 2012
Externally publishedYes

Keywords

  • insertion compounds
  • interface chemistry
  • Li-ion battery

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