HYDROTHERMAL PREPARATION AND CHARACTERIZATION OF LiMn_2O_4 FOR LI-ION BATTERY APPLICATION

摘要

A novel hydrothermal method was applied to prepare the precursor of LiMn_2O_4 using pre-treated electrolytic manganese dioxide (EMD) and lithium hydroxide as the main raw materials. The precursor was subjected to heat treatment between 400 and 900°C to obtain spinel Li_(1.05)Mn_(1.95)O_4 and Li_(1.o35)Co-(o.o35)Mn_(1.93o)O_4 positive materials for lithium ion batteries. The structure and morphology of the obtained powder materials were studied in detail by means of X-ray diffraction (XRD) and scanning electron microscope (SEM). It is found that the precursor has an amorphous structure and a high reactivity, which is easily transferred to spinel structure during heat treatment, obtaining a positive material with an uniform structure and good performances. The XRD patterns reveal that single phase spinel Li_(1.05)Mn_(1.95)O_4 can be obtained from the precursor after heat treatment at 600°C in air. The final Li-rich Li_(1.05)Mn_(1.95)O_4 product obtained showed a well-defined stable spinel structure and distinctive crystal faces with particle size between 200 and 300 nm. The as-prepared Co-doped spinel sample exhibited a excellent electrochemical performance with an initial discharge capacity of 113.0 mAh/g and 93.8% of its original value was retained after 100 charge-discharge cycling at 0.5 C.