Preparation of Fe Doped Li₂Ti₃O₇ and Its Electrochemical Properties

Abstract

Fe doped Li₂Ti₃O₇ has been prepared from TiO₂, LiCH₃CO₂ • 2H₂O and FeOOH. Single-phase compounds with rams-dellite structure were obtained by the heating at 950-1050°C. Fe doping decreases the formation temperature of rams-dellite phase. The limit of Fe doping to Li₂Ti₃O₇ at 1000°C is y ( = e/(Fe + Ti) in atomic ratio) = 0.265. The Rietveld refinement shows that Fe doping did not affect the size of lattice. The results of electrochemical test show that Fe doped Li₂Ti₃O₇ involves two redox reaction of Fe³⁺/Fe²⁺ couples and Ti⁴⁺/Ti³⁺ couples. The former reaction proceeds in the voltage range from 2.6 V to 1.5 V, and the latter one follows it. This is strongly supported by the agreement of calculated capacity based on Fe content with experimental one. Total discharge capacities of samples in the first cycle are 110-140 mAh/g for y≦0.189 and samples prepared at lower temperature show slightly higher capacities. All samples show excellent cycling performance.