Phase Change Induced Degradation of Amorphous Vanadium Oxide Cathode Thin Film during Charge-Discharge

H. Y. Park, S. R. Lee, W. I. Cho, H. K. Kim, S. M. Lee, J. S. Kim, Y. S. Yoon

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Amorphous vanadium oxide (V2O5) is a very good candidate as material for cathode thin film since it has a relatively high capacity. In addition, the room temperature deposition process is valuable in V2O5 thin film fabrication. Due to these advantages, much effort to grow amorphous V2O5 thin film has been made. In this research, we successfully grew amorphous V2O5 thin film using room temperature sputtering. Based on a Li/LiPON/V2O 5 full cell structure, charge-discharge performances were measured according to cycling number. Even though the full cell structure showed an average capacity of 15 μAh/cm2 over more than 500 cycles, a capacity fade was shown after a few cycles. Many reports revealed that the phase change of V2O5 from amorphous to crystalline made this kind of capacity fade. In order to investigate this phenomenon, high-resolution transmission electron microscopy (HRTEM) was employed. The as-deposited V 2O5 thin film consisted of a homogeneous amorphous without any grain-boundary and/or polycrystalline island. However, the microcrystalline V2O5 phase was randomly distributed in the amorphous V2O5 thin film matrix after 450 cycles by cross sectional TEM (XTEM). That is, some amorphous phase in the V2O5 matrix changed to the crystalline phase. This crystalline phase strongly prevented the extraction of Li ions during the charge process, which induced the irreversible diffusion of Li ions from cathode to anode. From this result, a high efficiency thin film battery based on amorphous V2O5 can be fabricated by preventing amorphous-crystal phase transformation during cycling.

Original languageEnglish
Pages (from-to)233-237
Number of pages5
JournalMetals and Materials International
Volume9
Issue number3
DOIs
Publication statusPublished - 2003 Jun

Keywords

  • Amorphous
  • Cathode
  • Phase transformation
  • Thin film battery
  • Vanadium oxide

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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