Enhanced High-Voltage Cycling Stability of Nickel-Rich Cathode Materials by Surface Modification Using LaFeO3 Ionic Conductor
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LaFeO3 is introduced as an ideal protective coating layer with excellent conductivity to enhance LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode material for use at higher operating voltage (especially 4.6 V). Various material characterization methods are employed to characterize the structural and morphological characteristics of the pristine and modified samples, including x-ray diffraction analysis, field-emission scanning electron microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy. The electrode with 2 wt.% LaFeO3 coating showed capacity retention of 80% at current density of 1 C after 200 charge/discharge cycles at 25°C, compared with 63% for the pristine electrode. Cyclic voltammogram results indicated that the LaFeO3 coating reduced the cell polarization during extended cycling. The results therefore show that LaFeO3 has potential for coating of NCM523 for use even at high voltage.
The authors acknowledge financial support from the National Science Foundation of China (51804149, 51764029), Provincial Natural Science Foundation of Yunnan (2018FD039), and National Key R&D Program of China (2018YFB0104000).