Effect of Fe and BO3 Substitution in Li1+xFexTi2-x(PO4)3-y</ sub>(BO3)y Glass Electrolytes

초록

The effect of Fe and BO3 doping on structure, thermal, and electrical properties of Li1+xFexTi2-x(PO4)(3-y)(BO3)(y) (x = 0.2, 0.5)-based glass and glass ceramics was investigated. In addition, their crystallization behavior during sintering and ionic conductivity were also investigated in terms of sintering temperature. FT-IR and XPS results indicated that Fe2+ and Fe3+ ions in Li1+xFexTi2-x(PO4)(3-y)(BO3)(y) glass worked as a network modifier (FeO6 octahedra) and also as a network former (FeO4 tetrahedra). In the case of the glass with low substitution of BO3, boron formed (PB)O-4 network structure, while boron preferred BO3 triangles or B3O3 boroxol rings with increasing the BO3 content owing to boic oxide anomaly, which can result in an increased non-bridging oxygen. The glass transition temperature (GTT) and crystallization temperature (CT) was lowered as the BO3 substitution was increased, while Fe2+ lowered the GTT and raised the CT. The ionic conductivity of Li1+xFexTi2-x(PO4)(3-y)(BO3)(y) glass ceramics were 8.85x10(-4) and 1.38x10(-4) S/cm for x = 0.2 and 0.5, respectively. The oxidation state of doped Fe and boric oxide anomaly were due to the enhanced lithium ion conductivity of glass ceramics.

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