Enhancing the Electrochemical Properties of Ti-Doped LiMn2O4Spinel Cathode Materials Using a One-Step Hydrothermal Method

Abstract

In this study, LiMn2-xTixO4 cathode materials were synthesized by a simple one-step hydrothermal method, and the effects of Ti doping on the sample structure and electrochemical properties were examined. The results indicated that Ti doping did not affect the spinel structure of LiMn2O4, and no other hybrid phases were produced. Furthermore, appropriate doping with Ti improved the particle uniformity of the samples. The electrochemical performance results showed that LiMn1.97Ti0.03O4 exhibited much better cycling performance than the undoped sample. The discharge capacity of LiMn1.97Ti0.03O4 reached 136 mAh g-1 at 25 °C at 0.2C, and the specific capacity reached 106.2 mAh g-1 after 300 cycles, with a capacity retention rate of 78.09%. Additionally, the specific capacity of LiMn1.97Ti0.03O4 was 102.3 mAh g-1 after 100 cycles at 55 °C, with a capacity retention rate of 75.44%. The Ti-doped samples thus exhibited an impressive high-rate performance. The discharge capacity of LiMn2O4 was only 31.3 mAh g-1 at 10C, while the discharge-specific capacity of LiMn1.97Ti0.03O4 reached 73.4 mAh g-1. Furthermore, to assess the higher Li+ diffusion coefficient and lower internal resistance of the Ti-doped samples, cyclic voltammetry and impedance spectra data were obtained. Our results showed that Ti doping enhanced the crystal structure of LiMn2O4 and improved Li+ diffusion, resulting in significant improvements in the cycling and rate performance of Ti-doped samples.