Abstract: Li_2+2xTi_1-xCu_x(NbO₄)_₂ was prepared by high temperature solid state reaction. XRD analysis shows that a olivine structure of LiFePO_4 can be found in the composition range
of x≤0.8. A.C. impedance measurements show that the initial composition of x=0.6 possesses the best conductivity of 1.26×10^-5 S/cm at room temperature, and that all samples with a
composition of x≥0.6 show the character of fast ion conductor. The sample with composition of x=0.6 was selected for electrode performance test, the results show that it has a very high
discharge specific capacity of 805.8mAh/g with a long discharge plateau at 2.0V during the first cycle in the voltage range of 0.5-4.6V vs Li⁺/Li at 0.10mA/cm² rate in 1mol/L LiPF₆/EC+DMC(1:1)
electrolyte and that its reversibility and cycle performance need to be improved.

Key words: lithium ion battery, cathode material, olivine structure