Improved cycling properties of a Li-rich and Mn-based Li1.38Ni0.25Mn0.75O2.38 porous microspherical cathode material via micromorphological control

Abstract

A practical strategy to enhance the electrochemical performance of Li-rich and Mn-based Li_1.38Ni_0.25Mn_0.75O_2.38 has been introduced. Its micromorphology and microstructure are controlled during the preparation process. Powder X-ray diffraction (XRD) and Raman spectroscopy reveal that the as-obtained materials can be indexed as the α-NaFeO₂ phase. Field emission scanning electron microscopy (FESEM) analyses demonstrate that the as-fabricated Li_1.38Ni_0.25Mn_0.75O_2.38 materials consist of 10–15 μm spherical secondary particles aggregating with spherical nanoscale primary particles, and the primary particle size and stacking faults can be controlled by altering the calcination temperature. The electrochemical measurements show that Li_1.38Ni_0.25Mn_0.75O_2.38 with nanoscale primary particles with the diameter of 100–200 nm and an appropriate amount of stacking faults obtained at 850 °C exhibits higher capacity and superior cycling performance, delivering an initial discharge capacity of 265.7 mA h g⁻¹ at 0.1C, 243.1 mA h g⁻¹ at 0.2C, 222 mA h g⁻¹ at 1.0C and 169 mA h g⁻¹ at 2.0C, accompanied with a capacity retention of 89.3% and 78.6% after 300 cycles and 500 cycles at 1.0C, respectively. Meanwhile, the XPS, EIS and TEM results of the electrodes indicate that the capacity fading in the first 50 cycles may be caused by interfacial side-reactions between electrode and electrolyte.