Improving the Electrochemical Performance of LiMn₂O₄by Amorphous Carbon Coating

A novel cyclohexanone hydrothermal method had been firstly adopted to synthesize LiMn2O4, which was then modified with carbon coating through a post-heat treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) exhibited that the particles were well-distributed and the primary grains were about 0.8 μm in size. Transmission electron microscope (TEM) indicated the LiMn2O4/C was uniformly coated with a carbon layer about 1.5 nm in thickness. The as-prepared bare LiMn2O4 exhibited a high initial discharge capacity of 127.9 mAh g−1 at 0.1 C, and the specific capacity increased to 138.5 mAh g−1 at 0.1 C by carbon coating. Moreover, it exhibited more excellent cycling maintaining 97.76% of its initial discharge capacity after 100 charge–discharge cycles. All the tests showed that LiMn2O4 with a carbon layer had excellent electrochemical performance, which was attributed to the carbon layer avoiding the core material direct contact with the acidic electrolyte and suppression of Mn+ dissolution into electrolyte.