Effect of Ti Substitution for Mn on the Structure of LiNi[sub 0.5]Mn[sub 1.5−x]Ti[sub x]O[sub 4] and Their Electrochemical Properties as Lithium Insertion Material

The effect of Ti substitution for Mn on the structure and electrochemical properties of the was studied. The was successfully synthesized at 900°C by solid-state reaction method. Additional annealing was used for the ordering of transition metals in octahedral sites. X-ray diffraction (XRD) and selected-area electron diffraction study clearly showed that Ti substitution leads to the disordering of the transition metals and consequently lowers the symmetry from primitive simple cubic structure to face-centered spinel Electron diffraction patterns of the showed stacking faults which came from the localized incorporation of Ti atoms in the lattice. exhibited higher operating voltages, faster lithium ion diffusion, and better rate capability than Ti-free confirmed by electrochemical tests including galvanostatic intermittent titration technique measurement. In addition, ex situ XRD data of the delithiated 0.3, and 0.5) showed that phase transition was suppressed with increasing Ti content. A large amount of Ti substitution in however, exhibited low discharge capacity, which would be due to the blocking migration pathway of electrons by the ions in octahedral sites. © 2004 The Electrochemical Society. All rights reserved.