Phosphate-based solid glass ceramic electrolytes for rechargeable lithium-ion/air batteries
Toh, Kang Hui.
Date of Issue2012
School of Materials Science and Engineering
Water-stable superionic lithium glass-ceramic electrolyte (GCE) system Li2O-Al2O3-GeO2-P2O5 (LAGP) was successfully prepared by melting and quenching method. A novel vitreous phase has been prepared by introducing boron oxide (B2O3), a renowned glass former in the parent LAGP system, which tends to increase the stabilization of the amorphous glass structure. Thus prepared LAGP – xB2O3 (x = 0.0 – 0.4 wt.%) system has been systematically investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), nuclear magnetic resonance (NMR), and ionic conductivity studies in the wide temperature range -30 – 100ºC. The ionic conductivity of grain boundary is observed to be maximum ~ 3.2 × 10-3 S cm-1 at 30 °C for the LAGP GCEs sintered at 850 °C for 12 h as compared to the samples sintered at other temperatures. An optimum amount of B2O3 (x = 0.3) adding on the conductivity of the LAGP system, shows very high thermal stability as well as σgb ~ 8.75 × 10-3 S cm-1 (higher by a factor of 3) at 30 °C. The highest σgb of LAGP – 0.3B2O3 is attributed to higher defect density and Li+ ion mobility achieved in the appropriate composition of LAGP and B2O3. In most cases low activation energy (~ 0.18 – 0.74 eV) for lithium transport was observed. It can be inferred that the B2O3-added LAGP electrolytes would be a hopeful candidate for all-solid-state battery because of simplistic preparation by the B2O3 addition, relatively high Li ion conductivity, and good interfacial stability against Li metal. Lithium nitride (Li3N) is well-known to provide the interfacial stability/interface with respect to lithium foil has also been added to the parent LAGP system to investigate its effects on stabilization of amorphous glass structure and its ionic conductivity.
Final Year Project (FYP)
Nanyang Technological University