Carbon coated to improve the electrochemical properties of LiMn2O4 cathode material synthesized by the novel acetone hydrothermal method

Abstract

Spinel LiMn2O4 particle is successfully synthesized by the acetone hydrothermal method without further sintered at high temperature. The electrochemical performances of LiMn2O4 at room temperature are improved by carbon modification through a post-heat treatment. SEM exhibits that the particles are well distributed and the primary grains are 5 μm in size. TEM indicates that the LiMn2O4/C is uniformly coated with a carbon layer about 2.0 nm in size. The electrochemical performances show that the pristine sample has an initial discharge capacity of 127.9 mAh g−1, and the capacity decreases to 110.6 mAh g−1 with the losses of 14.2 % after 100 cycles. Apparently, the LiMn2O4/C exhibits an initial capacity with 134.9 mAh g−1, and capacity losses of only 4.3 % after 100 cycles. At a discharge rate of 1 C, it keeps more than 97.18 % of the reversible capacity compared with that at 0.1 C. At the same time, the sample LiMn2O4/C shows only 5.84 % discharge capacity loss at the elevated temperature. The results show that the LiMn2O4/C sample with excellent electrochemical performances should attribute to the carbon layer avoiding the core material direct contact with the acidic electrolyte and suppression of Mn+ dissolution into electrolyte.