Electrochemical performance of LiCoO2 gradient coated LiNi0.96Co0.04O2 cathode

LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.08CoO2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-Ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the proper-ties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh center dot g(-1) and 207.90 mAh center dot g(-1) respectively, and the specific discharge capacity for the 100(th) cycle was still 186.02 mAh center dot g(-1) with an irreversible loss of only 21.1 mAh center dot g(-1). This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li(+)ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.