Investigation the electrochemical performance of Li1.2Ni0.2Mn0.6O2 cathode material with ZnAl2O4 coating for lithium ion batteries.

Layered solid solution materials Li 1.2 Ni 0.2 Mn 0.6 O 2 were synthesized with one sample heat treated and three other coated with ZnAl 2 O 4 with varying amounts (0.5, 1 and 2.5 wt%) at high temperature. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effect of ZnAl 2 O 4 coatings on the electrochemical performance of the pristine material was evaluated from charge/discharge cycles, rate performance, and electrochemical impedance spectroscopy (EIS). The results from TEM and selected area electron diffraction (SAED) indicate that the ZnAl 2 O 4 coating assumes a spinel structure on the Li 1.2 Ni 0.2 Mn 0.6 O 2 . The discharge capacities and coulombic efficiencies of the Li 1.2 Ni 0.2 Mn 0.6 O 2 materials in the first cycle are improved with the addition of ZnAl 2 O 4 . Li 1.2 Ni 0.2 Mn 0.6 O 2 coated with 1 wt% ZnAl 2 O 4 shows the highest discharge capacity (254.3 mAhg −1 ), highest capacity retention (98.6% for 50 cycles), and best rate capability (84 mAhg −1 at 10 C). EIS indicates that the resistance of Li 1.2 Ni 0.2 Mn 0.6 O 2 electrodes decrease with the addition of ZnAl 2 O 4 consistent with the excellent rate capability. [ABSTRACT FROM AUTHOR]