Mechanism of the interfacial reaction between cation-deficient La0.56 Li0.33 TiO3 and metallic lithium at room temperature

Kai Yun Yang, Ing Chi Leu, Kuan-Zong Fung, Min Hsiung Hon, Ming Chi Hsu, Yu Jen Hsiao, Moo Chin Wang

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14 Citations (Scopus)

Abstract

We used x-ray diffractometry (XRD), x-ray photoelectron spectrometry (XPS), and secondary-ion mass spectrometry (SIMS) to investigate the mechanism of the interfacial room-temperature (RT) chemical reaction between cation-deficient La0.56 Li0.33 TiO3 solid electrolytes and metallic lithium anodes in all-solid-state lithium batteries. A stoichiometric mixture of La2O3, Li2CO3, and TiO2 powders was calcined at 1250 °C for 8 h to obtain a single perovskite structure of La0.56 Li0.33 TiO3. When this La0.56 Li0.33 TiO3 sample and lithium were placed in contact at room temperature for 24 h, the phase of the La0.56 Li0.33 TiO3 remained unchanged. The XPS results indicate that 12% of the tetravalent Ti4+ ions were converted into trivalent Ti3+ ions. The valence conversion and degree of conversion were limited by the structural rigidity of the host crystal. Our SIMS analysis suggests the existence of a local electric field near the contact surface and indicates that the 6Li+ isotope ions were inserted into the specimen through the effect of this field. The change in the electrical properties of La0.56 Li0.33 TiO3 supports this mechanism for the interfacial reaction. The ionic conductivities of the grain and total grain boundary decreased and increased, respectively, after the insertion of Li+, and the total electronic conductivity increased as a result of the presence of intervalence electron hopping between mixed Ti3+/Ti4+ states. The mechanism of the lithium-activated RT interfacial reaction is associated with the reduction of Ti4+ transition metal ions from tetravalent to trivalent states and the local-electric-field-induced Li+ insertion into La3+/Li+-site vacancies of La0.56 Li0.33 TiO3.

Original languageEnglish
Pages (from-to)1813-1825
Number of pages13
JournalJournal of Materials Research
Volume23
Issue number7
DOIs
Publication statusPublished - 2008 Jul 1

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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