To figure out kinetic performance of LiMn_1.5Ni_0.5O₄ positive-electrode material, spinel LiMn_1.5Ni_0.5O₄ positive-electrode materials were prepared by a hydrothermal-assisted coprecipitation method. The structure and lithium ion insertion-extraction kinetic of the material were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results showed that LiMn_1.5Ni_0.5O₄ material powders prepared by coprecipitation method had a spherical morphology, a small particle size and narrow particle size distribution. During cycling of LiNi_0.5Mn_1.5O₄, the transfer resistance increased the diffusion coefficient of lithium-ion decreased, and then the electronic conductivity and ionic conductivity reduced. After the temperature rose, the solution resistance for LiNi_0.5Mn_1.5O₄ material changed a little, but the transfer resistance gradually increased and the diffusion coefficient of lithium-ion gradually decreased. In addition, the dissolution rate of LiNi_0.5Mn_1.5O₄ material was accelerated, and the thickness of solid electrolyte interphase (SEI) layer extended. The insertion-extraction kinetic of LiMn_1.5Ni_0.5O₄ material had a close relationship with temperature and cycle times.