Effect of Calcination Temperature of Size Controlled Microstructure of LiNi_(0.8)Co_(0.15)Al_(0.05)O2 Cathode for Rechargeable Lithium Battery

摘要

Size controlled, LiNi_(0.8)Co_(0.15)Al_(0.05)O2 cathode powders were prepared by co-precipitation method followed by heat treatment at temperatures between 750 and 850 °C. The synthesized samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The synthesized LiNi_(0.8)Co_(0.15)Al_(0.05)O2 after calcined at 750 °C has a good electrochemical performance with an initial discharge capacity of 190 mAh g~(-1) and good capacity retention of 100% after 30 cycles at 0.1C (17 mA g~(-1)). The capacity retention of LiNi_(0.8)Co_(0.15)Al_(0.05)O2 after calcined at 750 °C is better than that at 800 and 850 °C without capacity loss at various high C rates. This is ascribed to the minimized cation disorder, a higher conductivity, and higher lithium ion diffusion coefficient (D_(Li)) observed in this material. In the differential scanning calorimetry DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by calcined at high temperature, and this decrease is especially at 850 °C. This behavior implies that the high temperature calcinations of LiNi_(0.8)Co_(0.15)Al_(0.05)O2 prevent phase transitions with the release of oxygen.