Electrochemical performance of cobalt free, Li1.2(Mn0.32Ni0.32Fe0.16)O2 cathodes for lithium batteries

Cobalt free, eco-friendly layered Li-1.2(Mn0.32Ni0.32Fe0.16)O-2 compounds were synthesized using the adipic acid assisted sol-gel method. The structure and morphology of the prepared materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD results revealed that all of the materials possess a layered alpha-NaFeO2 structure with R (3) over barm space group. The TEM images confirmed the presence of carbon on the surface of the synthesized material. Galvanostatic charge/discharge studies demonstrated that the cyclic performance and rate capability of the materials were improved by the presence of carbon and the crystalline nature of the material. Among the synthesized materials, the sample prepared with 1 M adipic acid exhibited not only a high discharge capacity of 160 mAh g(-1), but also excellent cycling performance with a capacity retention of over 92% after 25 cycles. In addition, electrochemical impedance spectroscopy (EIS) was used to confirm the improvement in the electronic conductivity and the results are discussed in detail. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.