Electrochemical properties of tetravalent Ti-doped spinel LiMn2O4

Ti-doped spinel LiMn2O4 is synthesized by solid-state reaction. The X-ray photoelectron spectroscopy and X-ray diffraction analysis indicate that the structure of the doped sample is The first principle-based calculation shows that the lattice energy increases as Ti doping content increases, which indicates that Ti doping reinforces the stability of the spinel structure. The galvanostatic charge-discharge results show that the doped sample LiMn1.97Ti0.03O4 exhibits maximum discharge capacity of 135.7 mAh g(-1) (C/2 rate). Moreover, after 70 cycles, the capacity retention of LiMn1.97Ti0.03O4 is 95.0% while the undoped sample LiMn2O4 shows only 84.6% retention under the same condition. Additionally, as charge-discharge rate increases to 12C, the doped sample delivers the capacity of 107 mAh g(-1), which is much higher than that of the undoped sample of only 82 mAh g(-1). The significantly enhanced capacity retention and rate capability are attributed to the more stable spinel structure, higher ion diffusion coefficient, and lower charge transfer resistance of the Ti-doped spinel.