Improved electrochemical performance of Mn-based Li-rich cathode Li1.4Mn0.61Ni0.18Co0.18Al0.03O2.4 synthesized in oxygen atmosphere

Abstract

Mn-based Lithium-rich cathode materials suffer from poor cycle stability and rapid voltage decay during the cycling, which are the main bottlenecks inhibiting their applications. In this work, a new method for synthesizing of Li1.4Mn0.61Ni0.18Co0.18Al0.03O2.4 (LMNCA) cathode material in oxygen (LMNCA-O2) atmosphere is presented. The effects of synthesis atmosphere on the structural changes are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Rietveld refinement. As a result, the LMNCA-O2 material displays a lower Li/Ni disordering (Ni in Li Layer: 6.76%) and reduced amount of Li2MnO3 phase than that of the material synthesized in air (LMNCA-air), which can be attributed to the increased Ni3+ (55.925%) cations in the compound, as confirmed by XPS. LNCMA-O2 displays a high initial specific capacity of 229.1 mAh g−1 at 0.5 C in the potential range of 2.0–4.8 V and superior capacity retention of 93.63% after 100 cycles at 0.5 C. Additionally, good rate performance of 113.4 mAh g−1 at 5 C is also achieved for LNCMA-O2 cathode material when compared to that of 74.1 mAh g−1 for the LNCMA-air sample. The above findings obtained in the present approach offered a novel method for synthesizing the cathode material in a different way rather than the precursor approach.