Electrochemical Properties Of Li[Nixli(1-2x)/3mn(2-X)/3]O-2 (0 <= X <= 0.5) Cathode Materials Prepared By A Sol-Gel

Layered Li[Ni(x)i((1-2x)/3)Mn((2-x)/3)]O-2 (0 <= x <= 0.5) cathode powders were synthesized by a sol-gel process. The synthesized Li[NixLi(1-2x)/3Mn(2-x)/3]O-2 (0 <= x <= 0.5) powders were confirmed to be layered structure with a space group of R (3) over barm by X-ray diffraction (XRD) analysis. The extra diffraction peaks between 20 degrees and 30 degrees in the 2 theta scale indicates the superlattice ordering of Li, Ni and Mn in the transition metal layer. Further, there is no change in the structural parameters up to x = 0.2, and thereafter, the changes are significant with increase of x value to 0.5. The surface morphology of the synthesized electrode powders was examined by scanning electron microscopy (SEM) and an average particle size was found to be in an order of 0.1-0.4 mu m. The charge-discharge curves showed that the two distinguishable charge plateaus at the first cycle which were attributed to the Ni2+/Ni(4+)redox pair (<= 4.5 V) and partial loss of oxygen (>= 4.5 V), respectively. The stable discharge capacity of 260 mAh g(-1) was obtained at the end of the 20th cycle for the Li[Li0.2Ni0.2Mn0.6]O-2 electrode in the potential between 2.5 and 4.7 V at 12.6 mA g(-1). The electrode cell performance at x = 0.2 is the best among the studied x value in the Li[NixLi(1-2x)/3Mn(2-x)/3]O-2 System (c) 2005 Elsevier B.V. All rights reserved.