Applied Surface Science, Vol.331, 309-314, 2015
Significant improvement in performances of LiNi0.5Mn1.5O4 through surface modification with high ordered Al-doped ZnO electro-conductive layer
Al-doped ZnO (AZO)-coated LiNi0.5Mn1.5O4 (LNMO) was prepared by sol-gel method. Transmission electron microscopy (TEM) analysis indicates that AZO layer grown on the surface of LNMO is high ordered. The results of electrochemical performance measurements reveal that the AZO-coated LNMO electrode displays the best rate capability compared with the bare LNMO and ZnO-coated LNMO, even at a high rate of 10 C. The discharge capacity of the AZO-coated LNMO electrode can still reach 114.3 mAh g(-1), about 89% of its discharge capacity at 0.1 C. Moreover, AZO-coated LNMO electrode shows a remarkable improvement in the cyclic performance at a high rate at elevated temperature due to the protective effect of AZO coating layer. The electrode delivers a capacity of 120.3 mAh g(-1) with the capacity retention of 95% at 5 C in 50 cycles at 50 degrees C. The analysis of electrochemical impedance spectra (EIS) indicates that AZO-coated LNMO possesses the lowest charge transfer resistance compared to the bare LNMO and ZnO-coated LNMO, which may be responsible for improved rate capability. (C) 2015 Elsevier B.V. All rights reserved.
Keywords:Lithium-ion battery;High-voltage spinel;Surface modification;High ordered aluminum doped zinc oxide;Electrochemical performance