The layered oxysulfide LiNiS y O2−y compounds were synthesized and characterized to investigate the effect of sulfur on the electrode performance of LiNiO2. LiNiO2 precursors were first synthesized by a sol-gel method using adipic acid as a chelating agent and then doped with sulfur powders by a solid-state reaction under the flow of oxygen to prepare LiNiS y O2−y compounds. Pure LiNiO2 electrode showed a gradual decrease of discharge capacity with cycle number, whereas the capacity retention rate of LiNiS y O2−y electrodes significantly improved. The initial discharge capacity of the LiNiS y O2−y cells was lower than that of LiNiO2 cell and decreased with the increasing content of sulfur substituted in LiNiS y O2−y .