Peculiar electrochemical behaviors of (1 − x)LiNiO2·xLi2TiO3 cathode materials prepared by spray drying

The cathode materials, (1−x)LiNiO2·xLi2TiO3 with 0.05≤x≤0.5, were first prepared by a spray drying route. The XRD results indicated that co-substituting Li and Ti for Ni in LiNiO2 contributes to increasing cations disorder in the materials. Charge–discharge tests in the voltage range of 3.0–4.4 V exhibited expected results: the more simple charge–discharge curves, the deceased capacity and the increased Columbic irreversibility with increasing x. However, when charged up to 4.8 V, the materials with x≥0.075 surprisingly presented unusual electrochemical properties, an excess charge capacity beyond the oxidization of Ni3+ to Ni4+ in materials with the presence of a charge plateau at about 4.5–4.7 V during the initial cycle. These phenomena are very similar to those reported in (1−y)LiNi0.5Mn0.5O2·yLi2MnO3 [J. Electrochem. Soc. 149 (2002) A815]. The sample with x=0.05 indicated promising electrochemical properties in term of capacity and cyclability even charged to 4.8 V.