Synthesis and electrochemical performances of high-voltage LiNi_0.5Mn_1.5O₄ cathode materials prepared by hydroxide co-precipitation method

Spherical cathode material LiNi_0.5Mn_1.5O₄ for lithium-ion batteries was synthesized by hydroxide co-precipitation method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements were carried out to characterize prepared LiNi_0.5Mn_1.5O₄ cathode material. SEM images show that the LiNi_0.5Mn_1.5O₄ cathode material is constituted by micro-sized spherical particles (with a diameter of around 8 μm). XRD patterns reveal that the structure of prepared LiNi_0.5Mn_1.5O₄ cathode material belongs to Fd3m space group. Electrochemical tests at 25 °C show that the LiNi_0.5Mn_1.5O₄ cathode material prepared after annealing at 600 °C has the best electrochemical performances. The initial discharge capacity of prepared cathode material delivers 113.5 mAh·g⁻¹ at 1C rate in the range of 3.50–4.95 V, and the sample retains 96.2% (1.0C) of the initial capacity after 50 cycles. Under different rates with a cutoff voltage range of 3.50–4.95 V at 25 °C, the discharge capacities of obtained cathode material can be kept at about 145.0 (0.1C), 126.8 (0.5C), 113.5 (1.0C) and 112.4 mAh·g⁻¹ (2.0C), the corresponding initial coulomb efficiencies retain above 95.2% (0.1C), 95.0% (0.5C), 92.5% (1.0C) and 94.8% (2.0C), respectively.