Influence of post-annealing in N 2 on structure and electrochemical characteristics of LiNi 0.5 Mn 1.5 O 4

LiNi 0.5 Mn 1.5 O 4 prepared by a spray drying method was re-treated in N 2 at 500, 600 and 700 °C, respectively. Their structural and electrochemical properties were studied by means of Fourier transform infrared(FTIR), X-ray diffraction(XRD), and charge-discharge tests. The space group of the LiNi 0.5 Mn 1.5 O 4 transforms from P 4 3 32 to Fd3̅m at an annealing temperature of 700 °C. The electrochemical characteristics of the treated samples are closely related to the annealing temperature. The sample treated in N 2 at 500 °C shows both an improved rate capability and cyclic performance at a high temperature compared with the as-prepared sample, while the sample treated in N 2 at 700 °C shows dramatically decrease in its reversible capacity.