Ionothermal synthesis for Mg-doped LiMn1.5Ni0.5O4 spinel with structural stability and high-rate performance

The Mg-doped materials are synthesized by a novel ionothermal method using a kind of imidazolium-based ionic liquids as both reaction medium and structure-directing agent and successively followed by a calcination process. The tests show that the Mg-doped materials present uniform particles about 150 nm which are smaller than that of LiNi0.5Mn1.5O4. The result can be mostly due to MgCl2, which restrains the growth of the particles at high temperature. The electrochemical testing results demonstrate LiNi0.49Mg0.01Mn1.5O4 material has the capacity retention of higher than 96.9 % after 100 cycles, and high capacity of 105.3 mAh g(-1) at 10 C rate, in comparison with the capacity retention of 91.2 % and capacity of 82.4 mAh g(-1) for the pristine one. The excellent rate performance and cycling stability can be attributed to the small and uniform nanostructure, which can make the lithium-ion diffusion and electron transfer more easily across the LiNi0.49Mg0.01Mn1.5O4/electrolyte interfaces.