Dependence of structure and temperature for lithium-rich layered-spinel microspheres cathode material of lithium ion batteries

Homogeneous lithium-rich layered-spinel 0.5Li 2 MnO 3 ·0.5LiMn 1/3 Ni 1/3 Co 1/3 O 2 microspheres (~1 μm) are successfully prepared by a solvothermal method and subsequent high-temperature calcinations process. The effects of temperature on the structure and performance of the as-prepared cathode material are systemically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatical charge/discharge and electrochemical impedance spectra. The results show that a spinel Li 4 Mn 5 O 12 component can be controllably introduced into the lithium-rich layered material at 750°C. Besides, it has been found that the obtained layered-spinel cathode material represents excellent electrochemical characteristics. For example, it can deliver a high initial discharge capacity of 289.6 mAh g −1 between 2.0 V and 4.6 V at a rate of 0.1 C at room temperature and a discharge capacity of 144.9 mAh g −1 at 5 C and 122.8 mAh g −1 even at 10 C. In addition, the retention of the capacity is still as high as 88% after 200 cycles, while only 79.9% for the single-phase layered material. The excellent electrochemical performance of the as-prepared cathode material can probably be attributed to the hybrid structures combining a fast Li-ion diffusion rate of 3D spinel Li 4 Mn 5 O 12 phase and a high capacity of the layered Li-Mn-Ni-Co-O component.