Titanium phosphates as positive electrode in lithium-ion batteries: composition, phase purity and electrochemical performance

摘要

Titanium phosphate materials were synthesized by evaporation-induced self assembly method by using Ti(OC₄H₉)₄ and PCl₃, in the presence of Pluronic (P123) as a non-ionic surfactant template. The molar ratios of P/Ti and the heat treatment of the materials affected their structures, particle geometries and electrochemical performances as indicated by X-ray powder diffraction, thermal gravimetric analysis, scanning electron and transmission electron microscopy and other electrochemical techniques. As expected, increasing the temperature to 800 °C for 3 h resulted in losing the mesoporosity and generally led to a decrease in capacity of these materials. Cyclic voltammetry showed that TiP₂O₇ is formed at 500 °C for 10 h at a molar ratio P/Ti = 0.412 as amorphous phase. On the other hand, at molar ratio P/Ti = 2.06 showed sharp peaks indicated TiP₂O₇ transformed into crystalline material showed lower peak separation potential indicated that kinetic reactions might be favored.