Effect of F− and B3+ ions and heat treatment on the enhancement of electrochemical and electrical properties of nanosized LiTi2(PO4)3 glass-ceramic for lithium-ion batteries

Abstract

Abstract Preparation of LiTi2(PO4)3 (NASICON-type) glass ceramic from LiF.(2-x)TiO2.xB2O3.1.5P2O5 system were achieved via melt-quenching technique. The effect of gradual replacement of Ti4+ ions with B3+ ions was investigated. The prepared samples were characterized using differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy and high-resolution transmission electron microscope. The results revealed crystallization of LiTi2(PO4)3 as the major phase with traces of Li2TiF6 phase in the quenched samples. The quantities of these phases decreased with increasing B3+ ions until x = 1; beyond this value, B2O3 and β-Li4B2O5 were the dominant phases. After heat treatment at 800 °C/2 h, pure LiTi2(PO4)3 was detected till x = 1 then BPO4 appeared and increased with increasing B3+ ions. At x = 2, pure BPO4 was achieved. TEM revealed nanocrystalline size for the formed phase. In deduction, the substitution of Ti4+ ions by B3+ ions in the glass matrix improved the dc-conductivity at room temperature from 1.29 × 10−10 Ω−1 cm−1 in boron-free sample to 3.41 × 10−3 Ω−1 cm−1 for x = 2 sample due to the precipitation of β-Li4B2O5 in addition to B2O3. However, after heat treatment free boron sample (B0) showed the highest dc-conductivity at room temperature ∼1.23 × 10−4 Ω−1 cm−1 and lowest activation energy 0.032 eV. Therefore, the high conductivity, low activation energy and high diffusion coefficient (1.8 × 10−7 cm2/s) suggesting the use of the prepared materials in Li-ion battery applications.