Effects of Li-doped NiO on the charge-discharge properties of LiF-NiO composites used as cathode materials for Li-ion batteries

LiF-NiO composites are synthesized by the mechanical milling of LiF and Li-doped NiO (d_NiO) for 72 h. Li-d_NiO is prepared by the calcination of a mixture of Li2CO3 and NiO. The X-ray diffraction peaks of NiO are shifted by the doping and milling processes, while those of LiF disappear after milling. Rietveld analysis shows that the composites obtained by milling form solid solutions and that the Li+ and Ni2+ ions in them are disordered. LiF and Li-d_NiO samples milled individually do not exhibit a noticeable discharge capacity, while the composites show large values. The composite formed using undoped NiO without ball-milling shows a discharge capacity of 144 mA h g(-1) at 0.05 C between 2.0 and 5.0 V, while the composite of LiF and 20% Li-d_NiO exhibits a discharge capacity of 247 mA h g(-1). The rate capabilities of the composites increase with the Li content, and the discharge capacity of the LiF-Li-d_NiO (20%) is 146 mA h g(-1) at 1 C for voltages of 2.0-4.8 V. Discharge capacity of composite of LiF and Li(20%)-doped NiO is 247 mAh g(-1). [GRAPHICS] .