Electrochemical performance of cobalt free, Li_(1.2)(Mn_(0.32)Ni_(0.32)Fe_(0.16))O_2 cathodes for lithium batteries

摘要

Cobalt free, eco-friendly layered Li_(1.2)(Mn_(0.32)Ni_(0.32)Fe_(0.16))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 α-NaFeO_2 structure with R3m 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.