Dispersion of Li2SO4-LiPO3 glass in LiTi2(PO4)3 matrix: Assessment of enhanced electrical transport

Abstract

A novel mechanical milling assisted synthesis route has been used to prepare new generation Li+ ion glass-ceramic composites using (i) glassy system 60[Li2SO4]-40[LiPO3] (60LSLP) and (ii) Li+ NASICON, i.e., LiTi2(PO4)3 known as LTP. Effect of compositional alterations, sintering conditions and cooling process on electrical transport has been investigated. Preparation conditions along with compositional alterations have yielded in reporting the best conducting composition. The ionic glass content was varied in (60LSLP)y-(LTP)100-y matrix for y = 5–20 wt %. It has been observed that various parameters viz. milling time, composition, annealing temperature, time and cooling conditions have a significant impact on ionic transport. The highest in-grain (∼2 × 10−4 Ω−1 cm−1) and grain boundary (∼1 × 10−5 Ω−1 cm−1) Li+ ion conductivity values at 100 °C have been obtained for y = 20 wt%. These have been found to be significantly higher than that of the pristine LTP prepared with similar preparation conditions. Electrical response (Z″-ω) and dielectric relaxation (tan δ - ω) investigations suggest that mobile Li+ ions from glassy phase significantly contribute to conductivity. The elemental distribution investigations using Energy Dispersive X-ray Spectroscopy (EDS) mapping on fractured surface suggests homogeneous distribution of LTP and glassy phase in the composite. Cyclic Voltammetry (CV) results reveal no degradation in the electrochemical stability in 20 cycles, and that these composites are potential candidates for Li+ ion all-solid-state battery applications.