Ionothermal synthesis and enhanced electrochemical performance of nanostructure Cr-doped LiMn2O4 for lithium-ion batteries

LiCr (x) Mn2-x O-4 (x = 0, 0.02, 0.05, 0.12) materials were effectively synthesized by imidazolium-based ionic liquid as reaction medium at ambient pressure. The morphologies of Cr-doped LiMn2O4 via calcination were characterized by scanning electron microscopy (SEM). SEM reveals that the LiCr0.12Mn1.88O4 sample has regular nanostructure and a uniform particle size of 50-100 nm. Among the four samples prepared in ionic liquid, the charge/discharge tests indicate that LiCr0.12Mn1.88O4 presents the best performance of rate capacity and cycle stability. A typical LiCr0.12Mn1.88O4 delivers the initial discharge capacity of 129.6 mAh g(-1) and behaves a quite slow capacity fading with 96.8 % of initial capacity remained after 200 cycles at 0.5 C in the voltage range of 3.4-4.3 V. The improved electrochemical performance can be attributed to Cr doping and recyclable ionothermal method. Furthermore, this ionothermal synthesis is believed to provide a new reaction route for lithium-ion battery materials with mild reaction conditions.