A new approach to improve the electrochemical performance of Li-rich cathode material by precursor pretreatment

Abstract

The layered Li-rich 0.5Li2MnO3·0.5LiNi1/3Mn1/3Co1/3O2 cathode material was synthesized via a co-precipitation method. The carbonate precursor was pretreated in the mother liquor for various time and the effects on the electrochemical performance were studied. Field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were used to characterize the micromorphology and structure of the material. Meanwhile, charge-discharge test and electrochemical impedance spectroscopy (EIS) were employed to study its electrochemical performance. It was found that an extended precursor pretreatment time can result in relatively excellent hexagonal ordering structure and low degree of cation mixing. The material synthesized by the precursor aged in mother liquid for 12 h possessed excellent electrochemical performance. The initial discharge capacity was 262.7 mAh g−1 with the coulombic efficiency of 82.1% at 0.1 C. And the capacity retention after 50 cycles at 1.0 C was 76.9%. EIS test showed that the material had the lowest charge transfer resistance (32.02 Ω) and highest diffusion coefficientsDLi+(3.45 × 10−14 cm2 s−1).