| A series of serious problems including energy crisis, environmental pollution, global warming have already threatened the human well-being. To solve these problems above, governments and businesses have invested a lot of manpower and material resources in the development and utilization of electric cars. Lithium-Ion Batteries are quickly becoming an efficient energy choice used to power the vehicles. The spinel lithium manganate LiMn1O4 is one of the most promising cathode materials due to its low cost, good stability, non-toxic and high current charge/discharge performances. Therefore, the studies for higher-performance LiMn2O4 has attracted recent wide research interests. As is well known, both the surface size and morphological features of LiMn2O4 materials are important factors for improving electrochemical performances. This paper reports on the synthesis of MnO2 precursors by precipitation or hydrothermal method, the preparation and electrochemical performance of the LiMn2O4 cathode materials with different morphologies.In this paper, the cube structured MnCO3 was synthesized by a fast, simple, and surfactant-free co-precipitation method, and then was further calcined at high temperature. Finally, two types of cubic LiMn2O4 were prepared by a solid-state lithiation reaction of calcined and non-calcined MnCO3, respectively. XRD Pattern of calcined precursor MnCO3 was agreement with that of MnO2, indicating the transformation from MnCO3 into MnO2.The electrochemical performance of the cathode material LiMnO4 obtained from calcined MnC03 precursor is much better, compared to the one from non-calcined MnCO3, which delivered an initial discharge capacity of 116.9 mA h/g and a capacity retention of 80.0% after 100 cycles at 0.2 C rate, and remained average discharge capacity of 88.2 mA h/g at 2 C rate within the voltage range from 3.00 to 4.30 V.MnCO3 precursors with different morphologies were firstly obtained through precipitation or hydrothermal method and subsequently transformed into LiMn2O4 cathode materials through a solid-state reaction. What’s more, the specific surface area of MnCO3 precursors can be controlled by calcination reaction. And then coin cells were assembled using lithium metals as anode materials to test the electrochemical performance of the different LiMn2O4 cathode materials. The cathode materials LiMnO4 with nano-sphere shape posed a much higher performance than the others by comparison, which delivered an initial discharge capacity of 121.2 mA h/g and a capacity retention of 86.6% after 100 cycles at 0.2 C rate, and remained average discharge capacity of 103.5 mA h/g at 2 C rate within the voltage range from 3.00 to 4.30 V.The performance of spindle material is the last.The hollow spherical MnO2 was synthesized by hydrothermal synthesis and low temperature static method.Then the corresponding LiMn2O4 was synthesized by a solid-state reaction at high temperature. And their electrochemical performances were studied, and the hollow LiMn2O4 material obtained from the hollow MnO2 precursors by hydrothermal method exhibited the better properties among them, which delivered an initial discharge capacity of 112.6 mA h/g and a capacity retention of 86.9% after 100 cycles at 0.2 C rate, and remained average discharge capacity of 72.2 mA h/g at 2 C rate within the voltage range from 3.00 to 4.30 V. |
