Synthesis of LiCo0.3Ni0.7O2 as cathode materials for lithium ion batteries by oxidation-ion exchange of β-Co0.3Ni0.7(OH)2 and LiOH at low temperature

The single phase of LiCo0.3Ni0.7O2 was prepared by oxidation-ion exchange of β-Co0.3Ni0.7(OH)2 and LiOH at low temperature. The optimal synthetic conditions were determined as that the reaction was carried out at 120 °C for 12 h with a eight-fold LiOH added before the addition of oxidant (the molar ratio of K2S2O8:β-Co0.3Ni0.7(OH)2 is 1) and the obtained sample was washed to pH 11. The synthesized sample exhibits an initial discharge capacity of 130.0 mAh g−1 with 70.0% coulombic efficiency due to lower crystallinity. After heat treatment at 750 °C for 5 h, the initial discharge capacity is increased to 165.1 mAh g−1 and with a better capacity retention of 95.7% after 50 cycles, which is attributed to the improvement of the structural integrity. It suggests that the oxidation-ion exchange method together with heat treatment process is a very promising route to prepare the cathode material with good electrochemical performance for lithium ion batteries.