Crystallization Behavior of Phosphate Glasses with Hydrophobic Coating Materials

We analyzed the effect of the addition of Li2O3, TiO2, and Fe2O3on the crystallization behavior of P2O5–CaO–SiO2–K2O glasses and the effect of the crystallization behavior on the roughness and hydrophobicity of the coated surface. Exothermic behavior, including a strong exothermic peak in the 833–972 K temperature range when Fe2O3, TiO2, or Li2O3was added, was confirmed by differential thermal analysis. The modified glass samples (PFTL1–3) showed diffraction peaks when heated at 1073 and 1123 K for 5 min; the crystallized phase corresponds to Fe3(PO4)2, that is, graftonite. We confirmed that the intensity of the diffraction peaks increases at high temperatures and with increasing Li2O3content. In the case of the PFTL3 glass, a Li3Fe2(PO4)2phase, that is, trilithium diiron(III) tris[phosphate(V)], was observed. Through scanning electron microscopy and the contact angles of the surfaces with water, we confirmed that the increase in surface roughness, correlated to the crystallization of the glass frit, increases hydrophobicity of the surface. The calculated values of the local activation energies for the growth of Fe3(PO4)2on the PTFL1, PTFL2, and PFTL3 glass were 237–292 kJ mol−1, 182–258 kJ mol−1, and 180–235 kJ mol−1.

Synthesis, Characterization and Electrochemical Properties of Li1+xMn2O4 Spinels Prepared by Solution Combustion Synthesis

Li1+xMn2O4 prepared by solution combustion synthesis method has a strong exothermic peak at 282.1 °C, which is believed that the reaction of LiNO3, LiAc2•2H2O with Mn(NO3)2 and MnAc2•4H2O occurs in this region. So products were calcined at 500 °C would got fine crystalline. Pure phase LiMn2O4 can be prepared with x(Li)=0.16 and 0.24 without impurity. Li-rich samples for x(Li)=0.16 and 0.24 has nanoparticles of which the surface area will be more and can lead to better electrode performance. The initial discharge capacity of Li1.16Mn2O4 was the highest of 116.4mAh•g-1, with a 15 % loss of the initial capacity after 40 cycles, which is much better than bare LiMn2O4. Excess Li+ is beneficial to formation of pure phase of spinel LiMn2O4 and Li1.16Mn2O4 has best electrochemical performance in the method of solution combustion synthesis.