Morphological evolution of spinel disordered LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries by modified solid-state method

Abstract

The LiNi0.5Mn1.5O4 cathode material with high working voltage is a promising cathode material for next-generation lithium-ion batteries. In this investigation, LiNi0.5Mn1.5O4 materials with different particle sizes and crystal morphologies were synthesized by a modified solid-state method at different temperatures (750, 800, 850, and 900 °C). The evolution panorama of morphology and surface orientation with the temperature change of LiNi0.5Mn1.5O4 cathode materials were studied. The X-ray diffraction and scanning electron microscopy results showed that with the increase of temperature, the particle sizes increased and the crystal growth became more and more complete. Electrochemical tests showed that the material calcined under 850 °C exhibits a truncated octahedral structure and the best electrochemical performance. It delivers a discharge capacity of 124 mA h g−1 at 1 C; even at a high rate of 10 C, a capacity of 90 mA h g−1 can be obtained. The discharge capacity retention of the material is 91.2% after 150 cycles. In addition, the sample prepared by acetate reactant shows excellent electrochemical performance due to the truncated octahedron structure consisted of {111} and {100} surface as well as the appropriate particle size of ~ 1 μm. The {111} surface is conducive to stabilize the material structure, and {100} surface is conducive to the transfer of Li+ ion and electrons. At the same time, it also founded that the appropriate particle size could reduce the electrolyte corrosion of the material and easy for Li+ ion migration. As a result, the material exhibits an improved electrochemical performance.